Library of Congress Cataloging in Publication Data 

Roberts, Jean 

Refraction status and motility defects of persons 4-74 years, United States, 1971-1972. 

(Vital and health statistics: Series 11, Data from the National Health Survey; no. 206) 

(DHEW publication; no. (PHS) 78-1654) 

Supt. of Dots. no.: HE 6209: 1 l/206 

1. Eye-Refractive errors-United States~-Statistics. 2. Eye-Movement disorders-United 

States-Statistics. 3. Health surveys-United States. I. Rowland, hlichael, joint author. II. 

Title. III. Series: United States. National Center for Health Statistics. Vital and health statistics: Series 11, Data from the National Health Survey; no. 206. IV. Series: United States. 

Dept. of Health, Education, and Welfare. DHEW publication; no. (PHS) 78-1654. 

RA407.3.A347 no. 206 [ RE925] 312’.0973s 78-606048 

ISBN 0-8406-0131-X [312’3’0477550973] 
Data from the 

NATIONAL HEALTH SURVEY 

Refraction Status and Motility Defects 

of Persons 4-74 Years 

United States, 19714972 

National prevalence estimates of refraction status, refraction potential, and motility defects among the U.S. civilian noninstitutionalized 

population 4-74 years of age, including motility defects among 

children 1-3 years of age, with their demographic and socioeconomic 

distribution, based on the ophthalmology and medicaI history findings from the Health and Nutrition Examination Survey of 1971- 

1972. 

DHEW Publication No. (PHS) 78-1664 

Series 11 

Number 206 

U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE 

Public Health Service 

National Center for Health Statistics 

Hyattsville, Md. August 1978 
NATIONAL CENTER F:OR HEALTH STATISTICS 

DOROTHY P. RICE, Director 

ROBERT A. ISIRAEL, Deputy Director 

JACOB J. FELDMAN, Ph.D., Associate Director for Analysis 

GAIL F. FISHER, Ph.D., Associate Director’for the Cooperative Health Statistics System 

ELIJAH L. WHITE, Associate Director for Data Systems 

JAMES T. BAIRD, JR., Ph.D., Associate Directorfor Znternationul Statistics 

ROBERT C. HUBER, Associate Directorfor Management 

MONROE G. SIRKEN, Ph.D., Associate Director for Mathematicd S tutistics 

PETER L. HURLEY, Associate Directorfor Operations 

JAMES M. ROBEY, Ph.D., Associate Directorfor Program Development 

PAUL E. LEAVERTON, Ph.D., Associate Directorfor Research 

ALICE HAYWOOD, Information Officer 

DIVISION OF HEALTH IEXAMINATION STATISTICS 

MICHAEL A. W. HATTWICK, M.D., Director 

JEAN ROBERTS, Chief, Medical Statistics Brunch 

ROBERT S. MURPHY, Chief, Survey P&znning and Development Brunch 

Under the legislation establishing the National Health Survey, the Public Health Service is 

authorized to use, insofar as possible, the services or facilities of other Federal, State, or private 

agencies. In accordance with specifications established by the National Center for Health Statistics, the U.S. Bureau of the Census participated in the design and selection of the sample and 

carried out the household interview stage of the data collection and certain parts of the statir 

tical processing. 

Vital and Health Statistics-Series 1 I-No. 206 

DHEW Publication No. (PHS) 78-1654 

Library of Congress Catalog Curd Number 78-606048 
CONTENTS 

Introduction .............................................................................................................................................. 1 

Ophthalmology Examination ..................................................................................................................... 3 

Motility Testing .................................................................................................................................... 3 

Pinhole Test .......................................................................................................................................... 4 

Refraction ............................................................................................................................................ 4 

Medical History .................................................................................................................................... 5 

Quality Control .................................................................................................................................... 5 

Mokity ................................................................................................................................................ 

Refraction Status .................................................................................................................................. 

Refraction Potential ............................................................................................................................. 

Maximum Visual Acuity ....................................................................................................................... 

Population Size of Place of Residence .................................................................................................. 

Ancestry .._...._............~ ....................................................................................................................... 

Motility-Maximum Acuity .................................................................................................................... 

Medical History .................................................................................................................................... 

Comparison With Previous Studies ........................................................................................................ 

6 

6 

7 

9 

11 

19 

20 

21 

21 

24 

summary ................................................................................................................................................... 28 

References ................................................................................................................................................. 30 

List of Detailed Tables ............................................................................................................................... 31 

I. Statistical Notes ..- .......................................................................................................................... 104 

II. Demographic and Socioeconomic Terms.. ....................................................................................... 117 

III. Eye Condition Definitions .............................................................................................................. 119 

IV. Recording and History Forms ......................................................................................................... 121 

LIST OF FIGURES 

1. Prevalence rates of tropia and phoria among population age 4-74 years by age and sex: United 

States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 

2. Percent of population age 4-74 years with minus spherical equivalence (for myopia) or plus spherical 

equivalence (for hyperopia) in their present glasses or contact lenses by age: United States, 1971- 

1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~................................................................................... 

3. Percent of population age 4-74 years with minus spherical power (for myopia) or plus spherical 

power (for hyperopia) in their present glasses or contact lenses by age: United States, 1971-1972... 

6 

8 

4. Percent of population at selected ages in the range 4-74 years by strength of spherical equivalence in 

their present glasses or contact lenses by age: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

5. Percent of population age 4-74 years reaching specified visual acuity levels for maximum vision in 

the better eye: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

6. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better 

9 

10 

12 

eye by sex: United States, 1971-1972 . . . . . ..-...................................................................................... 13 

iii 
7. Percent of population with maximum distance vision of 20/50 or worse in the better eye by age and 

sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . ..I.............................................................................. 

8. Percent of white and Black population with maximum visual acuity of at least 20/20 in the better 

eye by age: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

9. Percent of population age 474 years with at least 20/20 maximum distance vision in the better eye 

by age and family income: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

10. Percent of white and Black population age 4-74 years with 20/50 or worse maximum distance 

vision in the better eye by age and family income: United States, 1971-1972, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

11. Percent change in proportion of population reaching 20/20 level in better eye on maximum over 

usual acuity by age, race, and region: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

12. Percent change in population reaching no better than 20/50 level in the better eye on maximum 

over usual acuity by age, race, and region: United States, 197 l-l 9 72 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

13. Percent of population age 6-74 years with maxbmum or usual better eye monocular visual acuity of 

at least 20/20 or no better than 20/50 according to whether or not they wear glasses or have 

trouble seeing with them: United States, 1971-11972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

14. Percent of U.S. children age 6-11 years in 1971-1972 and 1963-1965 and U.S. youths age 12-17 

years in 1971-1972 and 19661970 with tropia or phoria as determined by examination or test...... 

15. Percent of U.S. population wearing glasses or contact lenses by age in 1971-1972 compared with 

percent in 1960-1970 . . . . . . . . . . . . . ...” . . . . . . . . . . . . . . . . . . . . . . *, .,................................. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

16. Percent of adults age 18-74 years ever wearing glasses who have trouble seeing with them: United 

States, 1971-1972 and 1960-1962 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

TEXT TABLE 

A. Percent distribution of best corrected visual acuity in the better eye as determined for U.S. adults in 

1971-1972l and in the Framingham Eye Study in 1973-19752 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

SYIMBOLS 

Data not av&able -___--_-_-__--__--- ---_- ___-- ---___- - _ - 

Category not applicable ----- - -_-- --------- --.- . . . 

Quantity zero- ___-___ -- _-___-__-_ --------__--__-_ _ 

Quantity more than 0 but less than 0.05----- 0.0 

Figure dots not meet standards of 

reliability or precision-------------- * 

13 

14 

16 

17 

19 

20 

23 

24 

27 

27 

26 
REFRACTION STATUS AND MOTILITY DEFECTS 

OF PERSONS, 4-74 YEARS 

Jean Roberts and Michael Rowland, Division of Health Examination Statistics 

INTRODUCTION 

This report contains information on the 

refraction status, the refraction potential or 

maximum corrected visual acuity, and motility 

defects among persons 4-74 years of age based 

on findings from the eye examinations of a 

national probability sample of the U.S. civilian 

noninstitutionalized population during the first 

Health and Nutrition Examination Survey in 

1971-1972. The findings are analyzed with 

respect to age, sex, race, ancestry, region, 

population size of place of residence, annual 

family income, and responses to medical history 

questions on eye problems and use of glasses. 

The Health Examination Survey, in which 

these data were obtained, is one of the major 

programs of the National Center for Health 

Statistics authorized under the National Health 

Survey Act of 1956 by the 84th Congress as a 

continuing Public Health Service activity to 

determine the health status of the population. 

The data systems used to carry out the 

intent of the National Health Survey’ include, 

in addition to the Health Examination Survey, 

the Health Interview Survey, which collects 

health information from samples of people by 

household interviews and focuses primarily on 

the impact of illness and disability within 

various population groups; the Health Manpower 

and Facilities surveys, which obtain data on 

hospitals, nursing homes, and other resident 

institutions; and the Health Resources Utilization surveys, which obtain information on persons using health facilities and health manpower 

and the extent of that use. 

Of these programs the Health Examination 

Survey is the one designed to collect the kind of 

needed health statistics information obtainable 

most efficiently through direct examinations of 

probability samples of the population. From 

direct examinations, tests, and measurements, 

data are obtained in this program on the 

prevalence of medically defined illness-known 

as well as previously unknown or undiagnosed 

conditions-and on the distributions of a variety 

of health-related physical, physiological, and 

psychological measurements from which normative data and appropriate cutoff points for what 

is abnormal can be determined. Also collected 

are medical history, demographic, and socioeconomic data on the sample population under 

study with which the examination findings may 

be interrelated. 

Since 1960 the Health Examination Survejr 

has been conducted as a series of separate, 

consecutive programs called “cycles,” each of 

which is limited to some specific segments of the 

U.S. population and to specific aspects of 

health. During the first cycle in 1960-1962, the 

prevalence of certain chronic diseases, including 

eye pathology, and the distributions of various 

physical and physiological measures, including 

visual acuity, were determined among a defined 

adult population. 2 s3 For that survey, a national 

probability sample of 7,710 persons 18-79 years 

of age, of whom 6,672 (86.5 percent) were 

examined, was selected to represent the 111 

million in that age segment of the civilian 

noninstitutionalized U.S. population at that 

time. 

The target populations for the second and 

1 
third cycles in 1963-1965 and 1966-1970 were, 

respectively, the Nation’s noninstitutionalized 

children 6-11 years of age and youths 12-17 

years of age. 4$5 In both of these programs, the 

examination was focused primarily on health 

factors related to growth and development. For 

the second program, a probability sample of 

7,417 was selected to represent the nearly 24 

million noninstitutionalized children in the U.S. 

population, of whom 7,119 (96 percent) were 

examined. For the third program, a probability 

sample of 7,514 was selected to represent the 

22.7 million noninstitutionalized youths in the 

U.S. population at midsurvey. Of thlese, 6,768, 

or 90 percent of the sample were examined. 

The Health and Nutrition Examination Survey (HANES) program, from which the findings 

in this report were derived, was designed to 

measure the nutritional status of the U.S. 

population age l-74 years and to obtain some 

limited information on the general health status 

of the entire age group as well as more detailed 

information on the health status and medical 

care needs of persons age 25-74 years in the 

civilian noninstitutionalized population. A description of the specific content and plan of 

operation, including sample design, has been 

published.‘j 

As in the previous Health Examination 

Survey programs, the U.S. Bureau of the Census 

cooperated in the sample design and in the 

initial visits for interviewing at the eligible 

households in the primary sampling units 

(PSU’s) selected in various parts of the country. 

Members of the field teams of the mobile 

examination center did further household interviewing and explaining of the examination portion of the program. The selected sample persons for whom appointments could be made 

were brought into the specially constructed. 

mobile examination centers that were moved 

into a central location in each of the PSU’s. The 

team that traveled to the various survey locations throughout the country included professional and paraprofessional medical and dental 

examiners along with technicians, interviewers, 

and management staff. 

The probability sample design used in the 

study provided for oversampling, at predetermined rates, among the poor, preschool children, “women of childbearing ages, and the 

elderly, so that the nutritional status of these 

high-risk groups could be more accurately estimated. It further provided for a nationally 

representative subset of 35 of the :initially 

planned PSU’s throughout the United S,tates so 

that some preliminary national findings on the 

nutritional status of the population could be 

published before the total survey was completed 

and so that national estimates could be obtained 

from those parts of the examination which were 

included only in this 35-stand subsample. 

During the planning for the HANES program, Dr. Carl Kupfer, Director, National Eye 

Institute (NEI), indicated the interest of that 

Institute in obtaining more definitive information than was currently available on the prevalence and distribution of specific eye diseases 

and related conditions throughout the United 

States as an aid in setting goals and priorities for 

future emphasis in their programs. Consistent 

with the overall objectives of the survey, an 

evaluation of treatment needs also was incorporated into the examination. 

Two ophthalmologists from NEI, Drs. James 

P. Ganley and Arthur F. Garcia, developed the 

examination form and standardized protocol for 

the ophthalmic examination and were responsible for recruiting and training the examining 

ophthalmologists as well as for verifying the 

resultant diagnoses and for other aspects of 

quality control in this area. 

The NE1 decided to discontinue the ophthalmology examination after the completion of 

examining at 35 locations because of problems 

encountered in recruiting ophthalmologists to 

conduct the examinations and the lack of 

sufficient staff within the Institute to carry out 

the program adequately. While the size of the 

sample was not as large as originally planned, 

these unique national eye examination findings 

do provide the basis for analysis needed to meet 

most of the original purposes of this part of the 

examination. 

For the 35 locations at which the ophthalmological examination was given during the 

period between April 1971 and October 1972, a 

national probability sample of 14,147 persons 

was selected to represent the 192.7 million in 

the target population age 1-74 years. Despite 

intensive efforts, only 10,126 of the sample 

persons came in for examination. This represents 
72.8 percent of the sample persons selected 

when adjustments are made for the differential 

sampling rates for the age-sex-income-defined 

population subgroups. (The unadjusted overall 

response rate was 7 1.6 percent.) 

Surveys conducted by the National Center 

for Health Statistics, including all previous programs of the Health Examination Survey, have 

achieved higher levels of response than have 

been reached for the 35-stand subsample in this 

first Health and Nutrition Examination Survey. 

The 72.8-percent response rate fails to meet 

fully the requirements of the original probability 

design. However, after a policy of remunerating 

participants was initiated-adopted after the 

completion of examining at 20 locations-there 

was a significant increase in participation.7 

Because of the lower-than-usual response rate, 

the national estimates of the more severely 

visually disabled in this report will probably 

understate slightly the actual prevalence of this 

disability in the civilian noninstitutionalized 

population 25-74 years of age. The prevalence 

estimates in this report have been based on the 

findings for those examined. 

National estimates in this report are based 

on weighted observations; that is, the data 

obtained for each examined person were inflated 

to the level of the total population. The estimates have been calculated as though the examined persons in each of the age, sex, and 

income classes are a random subsample of the 

sample persons in the same class (appendix I). 

Although there is evidence from the earlier 

examination surveys and medical history data 

from the Health and Nutrition Examination 

Survey that these are not unreasonable approximations, it is clear that some estimates are 

subject to considerable risk of bias when more 

than one-quarter of the sample persons in a 

particular age-sex-income class were not examined. 

Even though examinees l-74 years of age 

were examined and tested by the survey ophthalmologists, visual acuity determinations were 

made only for those age 4-74 years. Hence, 

findings on refraction status and potential in this 

report are based on the examination of the 

9,263 persons age 4-74 years at the time of 

examination. The extent of and the methods 

used in the estimation of missing data for the 

various examination components used in this 

report are shown in appendix I. 

Definitions of demographic and socioeconomic terms used in this report are in appendix 

II and disease or condition definitions in 

appendix III. 

OPHTHALMOLOGY EXAMINATION 

At each of the 35 selected locations throughout the country, arrangements were made for 10 

different sample persons to come or be brought 

into the specially designed mobile center for 

each of the morning, afternoon, and evening 

examination sessions. These included 10 examinees from the nutrition sample (l-74 years) 

including 2 who were also selected for the 

detailed sample (25-74 years). The ophthalmology examination, one of the first procedures 

scheduled in each session, was similar for persons in the nutrition sample and for those in the 

detailed sample except for the refraction component in which determination was made of 

maximum or best corrected acuity. The standardized eye examination for those over 3 years 

of age included the taking of an ocular history 

regarding previously known eye disorders or 

previous eye surgery; a determination of monocular distance visual acuity with usual correction, 

if any, and with a pinhole test to measure 

correctability for those with acuity less than 

20/20; determination of type of motility defects; measurement of prescription in present 

glasses’; dilation, and within 20 to 70 minutes 

thereafter, retinoscopy for detailed examinees 

with acuity less than 20/40 and spherical trial 

lens test for nutrition examinees with acuity less 

than 20/40; applanation tonometry on examinees 20 years and older; and examination of 

the pupils, lids, globes, conjunctiva, sclera, 

corneas, anterior chambers, irides, and lenses. 

The pupils were dilated in most instances for the 

spherical refraction and retinoscopy and for the 

examination of the vitreous and retina. 

Motility Testing 

The eye muscle part of the examination 

consisted of a careful inspection and clinical 

testing for evidence of nystagmus and manifest 

3 
tro ia s ra 

!mbLa?lcd b 

ismus or latent (phoria) eye muscle 

. 

Examinees were tested in the six cardinal 

directions of gaze. Then the alternate-cover test 

and cover-uncover test were done at near (14 

inches) and distance (20 feet) with an accommodative fixation target (e.g., fixation symbol 

for near and 20/40 letter for distance). The 

motility examination was done with vision 

corrected if glasses were available and through 

bifocals or reading glasses, if available. 

For each eye, the examiner checked the 

examinee in the cardinal directions by having 

him follow a near fixation target while looking 

for limitations of gaze. The cover-uncover test 

(for tropia) was performed by having the examinee observe a stationary accommodative test 

object while the examiner covered one eye of 

the examinee and looked for movement of the 

fellow eye; the alternate cover test (for phoria) 

was performed by alternately covering one eye 

of the examinee and then the other while 

looking for movement of the eye just uncovered. 

By these techniques, phorias and tropias were 

detected and differentiated. 

When a tropia was detected, the type of the 

condition was recorded as eso or exo, hyper or 

not hyper, and comitant or not comitant. 

Similarly, the presence of a phoria was indicated 

with a designation of whether eso or exo and 

hyper or not hyper (appendix IV). 

The presence of true nystagrnus (excluding 

voluntary or end-position nystagmus) was recorded by type-pendular, jerk-horizontal, jerkvertical, or jerk-rotary (appendix III). 

Pinhole Test 

When the best distance vision in the initial 

visual acuity tests before dilation and refraction 

was less than 20/20 in the eye under test, the 

examiner, leaving in place the examinees’s own 

glasses or contact lenses if worn in the initial 

tests, placed a pinhole in front of the eye under 

test and recorded the distance acuity reached. 

with this device also. 

Refraction 

The prescription for the present distance 

correction was determined for those examinees 

who brought their glasses or contact lenses to 

the examination. For all examinees whose best 

visual acuity in either eye was 20/50 or worse, 

corrected or uncorrected, spherical refraction 

(nutrition examinees) and retinoscopy (detailed 

examinees) were done to determine the maximum visual acuity possible for them as well as 

the characteristics of the lens required. 

Prescription in present glasses.-A E’owerite 

II Lensometer was used by the exammer in 

measuring the spherical and cylindrical power 

and the axis deviation for the distance correction in the refractive lenses worn by the examinee. Untinted lenses were measured through 

the green filter and dark lenses were measured 

with the filter removed. A special attachment 

was used for making measurements on contact 

lenses. 

The measurements were carefully made 

starting with the power scale set on zero and the 

target lines put in sharp focus. The lens was then 

clamped in the holder. The power whieel was 

rotated until the target lines were at&tin in 

approximate focus and the lens had been centered for measuring. The power wheel was then 

rotated until the sphere power lines came into 

sharp focus. The power of the spherical correction in the lens from the power scale was 

recorded with the appropriate sign to the nearest 

hundredth of a diopter. The power wheel was 

again rotated until the cylindrical power lines 

came into sharp focus and the appropriate 

power wasrrecorded to the nearest hundredth of 

a diopter. The degree of axis deviation between 

the spherical and cylindrical lenses also shown at 

that time on the power wheel was recorded to 

the nearest degree. 

Spherical refraction.-For the nutrition examinees whose best distance vision in either eye 

was 20/50 or worse, corrected or uncorrected 

(not including pinhole vision), refraction was 

limited to that possible with graded spherical 

trial lenses. Within 20 to 70 minutes after 

dilation, with the examinee seated in position by 

the Reliance Instrument Stand, the examiner 

tried to improve the distance visual acuity in the 

eye with poor vision, leaving glasses or contact 

lenses on for those who wore them, by inserting 

in the refractor suspension positioned in front of 

the examinee simple spherical lenses in .50- 

4 
diopter increments (e.g., -1.00, -1.50 or +2.50, 

+3.00, etc.) from the trial lens set. When the 

maximum distance visual acuity was reached for 

the eye being tested, the examiner recorded the 

sign and strength of the added spherical correction and the final acuity level obtained (appendix 

IV). 

Retinoscopy.-For detailed examinees whose 

best distance vision in either eye was 20/50 or 

worse, corrected or uncorrected (not including 

pinhole vision), within 20 to 70 minutes after 

dilation, the examiner determined the refractive 

error in the eye with the poor vision (with 

glasses or contact lenses if worn), using a 

Copeland streak retinoscope but without doing a 

manifest refinement, and measured and recorded 

the visual acuity. The strength of the added 

spherical and cylindrical lenses, their axis deviation, and the maximum acuity level reached 

were recorded. 

Visual acuity testing during the spherical 

refraction and retinoscopy was done using methods previously described.* 

Medical History 

During their visit to the sample household to 

make the appointments for the examination, the 

HANES field representative administered a medical history to the parents for children age 6-11 

years and to the sample person for those 12-74 

years of age. The history for the child included 

11 questions directly related to the use of glasses 

and vision difficulties or other eye conditions; 

the history for those 12-74 years old included 8 

such questions (appendix IV). 

Quality Control 

Drs. Ganley and Garcia, senior ophthalmologists from NEI, were responsible for recruiting the 91 survey ophthalmologists and for 

training them in the standard examination procedures used at the first 35 examination locations of the Health and Nutrition Examination 

Survey. 

In addition, these senior ophthalmologists 

from NE1 developed a protocol for supervised 

testing, which they carried out at 24 of the 35 

locations, to insure the accuracy of the ophthalmology examination data, to provide an estimate of their replicability or reliability, and to 

aid in maintaining uniformity in the examination procedures. 

To accomplish these objectives, the examinations of all sample persons in the first 2 sessions 

at each of 24 of the 35 stands were observed and 

partially replicated by the senior ophthalmologists of NE1 who then evaluated the methods and findings of the examiners and made the 

necessary recommendations where needed. The 

NE1 observer conducted the first part of these 

examinations simultaneously with the examiner 

and recorded his findings on a separate replicate 

form made out for each patient. Motility tests 

and lensometer measurements of the distance 

correction in the examinee’s present glasses were 

each replicated in this manner. 

The examiner was observed for technique, 

facility with the instruments, and adherence to 

the protocol. Written comments were made on 

the observer’s record including specific problems 

or questions that arose during the examination. 

Recommendations to the examiner, if needed, 

were made at the end of each session. 

At the end of each session, after the examiner’s findings had been transferred to the 

“replicate” examination form, the examiner’s 

evaluation of each examinee was compared with 

that of the observer. 

In all, 230 (2.5 percent) of the 9,263 

ophthalmology examinations were repeated by 

the senior ophthalmologists in this way. Motility 

examination results showed a high level of agreement between examiner and observer findings 

(appendix I, table IV). Of the 230 examinations 

replicated, exact agreement was obtained on the 

presence or absence of a given condition on 

more than 97 percent of the examinations for all 

conditions except esophoria or exophoria for 

which the agreement was 82 percent. However, 

the results indicate some difficulty in condition 

identification (i.e., direction of deviation). Of 

those examinees identified by examiner or 

observer as having a specific eye muscle problem, examiner-observer agreement ranged from 

33 percent for hypertropia to 100 percent for 

hyperphoria. 

In replication of the lensometer measurements of the correction in the examinees’ 

present glasses, complete agreement was reached 
on the power of the spherical correction for 65 

percent of the lenses, on the power of the 

cylinder correction for 78 percent, and on the 

axis deviation for 34 percent. Differences between original and replicate measurement of 

0.50 prism diopter or more were shown for 19 

percent of the spherical correction measurements and 2 percent of the cylindrical correction. On the axis deviation measurements, the 

error was no more than 10 degrees (10’) for 68 

percent but differed by 45’ to 89’ for 12 

percent, and by 90” to 178’ for 15 percent 

(appendix I, tables V and VI). 

The average difference between examiner 

and observer indicates essentially no consistent 

bias in these measurements. On spherical corrections, the average difference on all replicate 

measurements was -0.05 diopter for the spherical correction measurements, -0.06 diopter for 

the cylindrical, and -6.0’ for the axis deviation. 

FINDINGS 

Motility 

An estimated 38 million, or 19.5 percent, of 

the civilian noninstitutionalized population l-74 

years of age in the United States have a manifest 

or latent eye muscle imbalance condition. Less 

than 1 percent (0.7 percent) have more than one 

such condition in their two eyes. (See appendix 

III for definitions9 of the various types of eye 

pathology or defects included in this report.) 

These estimates are based on findings from the 

Health and Nutrition Examination Survey of 

1971-1972 among a national probability sample 

of that age in the U.S. population. 

Tropic.-More than 7.1 million or 3.7 percent of persons l-74 years of age in the United 

States have a disturbance of coordination of the 

extraocular muscles of the two eyes, which is 

retained in all six cardinal positions of gaze 

whether one eye is covered or not (table 1). Of 

those persons with such manifest eye muscle 

imbalance (also frequently referred to as manifest strabismus), 2.3 million (1.2 percent of the 

population 1-74 years of age) have an inward 

deviation of one or both eyes (esotropia); 4.0 

million (2.1 percent), an outward deviation 

(exotropia); and 1.2 million (0.6 percent), an 

upward deviation (hypertropia). For the major6 

ity of these 4.0 million persons (2.1 percent of 

the population age 1-74 years), there was no 

apparent muscle weakness causing the tropia 

(comitant type). Only 0.6 million persons (0.3 

percent of the population) had an impairment of 

one or more of the eye muscles or their nervous 

connections which caused the tropia (incomitant 

type); for the remaining 2.5 million persons (1.3 

percent of the population) with tropia, the cause 

could not be definitely identified. Aftelr more 

complete examination of the eye, the ophthalmologist identified less than 0.1 percent as 

having a tropia condition not detected in his 

original motility testing and considered 98 percent of the tropia to be significant ‘ocular 

pathology. 

Among older persons age 55-75 years, the 

prevalence of tropia (6.1 percent) is substantially greater than it is for very young children 

1-3 years (1.9 percent) or children and younger 

adults 4-54 years (3.3 percent). 

Females l-54 years of age are more likely 

than males of the same age to have a tropia, in 

contrast with the negligible sex difference in the 

prevalence rates of manifest motility disorders 

among adults 55-74 years (figure 1). 

30 r q Tropia - 

q Phoria 

25 - 

k!2 

B 20 - 

L 

x 

9 

: t15 - 

El 

:! 

!I 

2 10 - 

YI. 

E 

5- 

0 

M.les FemdeS Males 

4-24 YEARS 25.54 ‘I 

Femsler 

‘EARS 

M&S Females 

55.74 YEARS 

Figure 1. Prevalence rates of tropia and phoria among population age 4-74 years by age and sax: United States, 1971- 

1972 
There is no significant racial difference in 

the prevalence of tropia: The rates are negligibly 

higher among the white than among the Black 

population ages l-54 years and lower at 55-74 

years, but all differences are small enough to be 

due to sampling variability alone. Nor does the 

tropia prevalence rate show any consistent association with income level across the age range in 

this study (table 2). 

Phoria-An estimated 30.8 million (16.0 

percent) of the U.S. civilian noninstitutionalized 

population l-74 years of age have a latent 

tendency for one eye to deviate so as to look at 

a different image than the other eye focuses on 

when fusion or binocular viewing is interrupted 

(table 3). For approximately 4.0 million (2.1 

percent of the population), the latent tendency 

is for an inward deviation (esophoria); for 26.6 

million (13.8 percent), the deviation is outward 

(exophoria); and for 0.8 million (0.4 percent), 

there is a latent tendency for an upward 

deviation of one eye (hyperphoria) usually in 

conjunction with one of the other types of 

phoria. 

The prevalence of phoria increases with age 

from 3.3 percent among preschool-age children 

age l-3 years to 14.8 percent among children 

and young adults age 4-24 years, then increases 

more slowly to 19.7 percent at ages 55-74 years. 

Females age 4-24 years are slightly more 

likely than are males to have a phoria condition 

(16.4 percent compared with 13.3 percent for 

males), but the difference in the rates is not 

large enough to be statistically significant at the 

5-percent probability level. Across the remainder 

of the age range, the sex difference in these rates 

is negligible. 

The racial differences in the prevalence of 

phoria are small enough to be reasonably attributable to sampling variability alone, although 

the observed rates among the white population 

age l-54 years are lower and at age 55-74 years 

higher than the corresponding rates among the 

Black population, the reverse of the pattern 

shown for tropia. 

Nystugmus.-Nearly 1.0 million (0.5 percent) of the U.S. population (civilian noninstitutionalized) 1-74 years of age have an involuntary 

more or less rhythmic, back-and-forth movement of the eyes (table 4). The condition is 

more likely to be of the jerk type than of the 

pendular type. On the more detailed examination of the eye, the ophthalmologists considered 

only 62 percent of these conditions to be 

significant ocular pathology. 

There appears to be some consistent increase 

in the prevalence of nystagmus with age-from 

0.3 percent at age l-3 years to 0.9 percent at age 

55-74 years-but the sample size used for the 

survey is too small to provide sufficiently 

reliable estimates to assume that this apparent 

trend represents more than sampling variability. 

Refraction Status 

More than one-half (52.4 percent), or an 

estimated 92 million, of the civilian noninstitutionalized population 6-74 years of age in this 

country wear corrective lenses (glasses or contact lenses) all or part of the time, according to 

the medical history findings from the Health and 

Nutrition Examination Survey. Information regarding the present refraction status of the U.S. 

population in this report is limited to that 

obtained regarding distance vision on the 40.7 

percent of this 6-74-year-old group who brought 

their own glasses or contact lenses to the 

examination and to the 4.3 percent of the 4- 

and 5-year-olds who were wearing glasses at the 

time of the examination (2.4 percent of the 

4-5-year-old examinees, presumably those wearing glasses for distance vision). The proportion 

for whom distance refraction status could be 

determined (36.7 percent of ah examinees age. 

6-74 years) was greater among females (39.6 

percent) than among males (33.1 percent); the 

sex differential was somewhat smaller but in the 

same direction as that existing among all those 

reported on medical history as still wearing 

corrective lenses. Approximately 29.5 percent of 

those 6-74 years of age who wear corrective 

lenses, or an estimated 27.1 million persons, 

failed to reach the 20/20 level with either eye 

when wearing their own corrective lenses. 

The prescription in their present correction 

was measured with a lensometer for those who 

brought their glasses or contact lenses to the 

examination with them. The distribution of 

these measurements of the spherical and cylindrical power of the lenses and the degree of axis 

deviation of the cylinder are shown in tables 

5-12. The spherical equivalence of the lens 

7 
system in these glasses or contact lenses, as 

estimated from the algebraic sum of the spherical power and one-half the power of the 

cylindrical correction, is shown in table 13; the 

unadjusted power-the algebraic sum of the 

spherical and cylindrical corrections-as shown 

in table 14, will give an overestimate of the 

effective strength of the correction. 

Among the population 4-74 years of age 

who were wearing glasses (or contact lenses) at 

the time of the examination, the correction was 

about as likely to be for myopia (nearsightedness) as for hyperopia (farsightedness). 

On the basis of the spherical power alone, 47.6 

percent had a negative spherical correction (for 

myopia), 46.7 percent had a positive spherical 

correction (for hyperopia), and 5.8 percent had 

no spherical correction in their lenses (table 5). 

When the spherical equivalence of the lens system is considered, 48.1 percent showed a correction for myopia, 48.3 percent showed a correction for hyperopia, and 3.4 percent showed no 

measurable correction (table 13). 

There is a significant trend with age in the 

type of corrective lenses used on the basis of 

either the spherical equivalence of the lens 

system or the spherical power alone (figures 2 

and 3). When the spherical equivalence is considered, the proportion with a correction for 

myopia increases with age among children from 

30.2 percent at 4-5 years to the maximum of 

87.2 percent at 12-17 years, then consistently 

decreases to a minimum of 15.7 percent at 

65-74 years. The trend with respect to the 

prevalence of hyperopia is the reverse of that for 

myopia. Among children, the proportion with 

correction for hyperopia decreases with age 

from 66.0 percent at 4-5 years to the minimum 

of 10.7 percent at 12-17 years, then increases 

consistently to the maximum of 81.4 percent 

among the oldest age group, 65-74 years. The 

trend with age in the type of correction in 

people’s glasses (or contact lenses) based on the 

measurement of the spherical power alone is 

very similar to that shown for the more complete measure of the spherical equivalence of the 

lens. 

The strength of the negative spherical correction may be seen to be at a maximum at 12-24 

years then decreases with age; the strength of 

the positive spherical correction increases with 

8 

1oc 

80 

60 

40 

20 

ii? 

z 

s 

b 0 

5 

g 

E 

20 

40 

60 

80 

100 

Minus spherical equivalence 

Ezl Plusspherical equivalence 

6.11 12.17 18.24 25.34 35.44 45.54 55.64 65.74 

AGE IN YEARS 

Figure 2. Percent of population age 4-74 years with minus 

spherical equivalence (for myopia) or plus spherical equivalence (for hyperopia) in their present glasses or contact 

lenses by age: United States, 1971-1972 

age from the minimum at 12-17 years to a 

maximum at 65-74 years (tables 13, 14, and 

figure 4). 

There is no statistically significant difference 

between the right and left eye lens or between 

those used by males and females with respect to 

the distribution of the power of the lens or lens 

system (table 11). 

With respect to the cylindrical power in the 

lens system and to the axis deviation of the 

cylinder, there is no consistent age trend (tables 

6 and 12). 
100 q Minus spherical power 

80 

60 

- 

60 

80 

103 

6.11 12.17 18.24 25.34 3544 45.54 55.M 65.74 

AGE IN YEARS 

Figure 3. Percent of population age 4-74 years with minus 

spherical power (for myopia) or plus spherical power (for 

hyperopia) in their present glasses or contact lenses by age: 

United States, 1971-1972 

Refraction Potential 

Pinhole test.-Of the estimated 63.2 million 

persons (or 34.7 percent of the population) 4-74 

years of age whose usual visual acuity with their 

own glasses or contact lenses if worn was less 

than 20/20 in one or both eyes (when tested 

before dilation), 16.0 percent were able to reach 

the 20/20 level on retest after a pinhole was 

placed over their usual correction (table 15). 

The proportion of persons’ eyes in which acuity 

could be improved to 20/20 with just the use of 

the pinhole was at a maximum of 23.1 percent 

for those testing at the 20/25 level, then 

declined steadily with decreasing visual acuity 

on the regular test to 0.5 percent among those 

whose acuity in the initial test had been 20/80. 

Among the small number testing (initially) at 

the poorer acuity levels of 20/100, 20/200, and 

20/400, the percents that improved to 20/20 

with the pinhole were, respectively, 1.7, 6.4, and 

2.2. 

The proportion of persons’ eyes in which 

acuity could be improved at all with the pinhole 

alone increased consistently from the 23.1 percent initially testing at the 20/25 level to 87.5 

percent among those initially testing at the 

20/70 level and reached a maximum of 9 1.4 

percent among those testing initially at 20/100. 

The proportion whose visual acuity through the 

pinhole was poorer than in the initial test was 

less than 2 percent. 

This pattern of association between usual 

visual acuity and pinhole visual acuity is similar 

for the three age groups-4-24, 25-44, and 45-74 

years-although the middle age group is somewhat more likely and the oldest age group 

somewhat less likely to show improvement to 

the 20/20 level than the youngest age group is; 

the respective percentages are 24.0 (25-44 years), 

11.1 (45-74 years), and 18.5 (4-24 years) (tables 

16-18). 

Refraction.-Within 20 to 70 minutes after 

dilation, refraction potential was determined or 

estimated for each examinee whose usual visual 

acuity in either eye was 20/50 or less with his 

own glasses or contact lenses, if worn, otherwise 

uncorrected. Among the examinees in the nutrition sample who were not included in the 

detailed sample-about 81 percent of all examinees, all of those 4-24 years of age and about 

four-fifths of adults age 25-74 years-refraction 

potential was estimated by the extent to which 

acuity could be improved with just the addition 

of spherical lenses. For examinees in the detailed 

sample-one-fifth of the adults age 25-74 years 

or about 19 percent of the sample-actual 

refraction potential was determined using retinoscopy. 

Among the 6.6 percent of the population 

age 4-74 years whose usual visual acuity in the 

right eye was 20/50 or worse, an estimated 22.3 

percent reached the 20/20 level at distance with 

9 
50 r 6-11 YEARS 12.17 YEARS 

OVW 3.1. 1.1. 0.1. 0 0.1. 1.1. OW OVW 3.1. 1.1. 0.1. 0 0.1. 1.1. OW 

5 5.0 3.0 1.0 1.0 2.0 2 5 5.0 3.0 1.0 1.0 2.0 2 

Minus PIUS Minus PIUS 

35.44 YEARS 

0 

50 

40 

30 

20 

10 

0 

OVW 3.1. 1.1. 0.1. 0 0.1. 1.1. OVU OVW 3.1. 1.1. 0.1. 0 0.1. 1.1. Over 

5 5.0 3.0 1.0 1.0 2.0 2 5 5.0 3.0 1.0 1.0 2.0 2 

Minus PIUS Minus PIUS 

DIOPTERS OF SPHERICAL EQUIVALENCE DIOPTERS OF SPHERICAL EQUIVALENCE 

Figure 4. Percent of population at selected ages in the range 4-74 years by strength of spherical equivalence in their present glasses or 

contact lenses by age: United States, 1971-1972 

additional spherical correction or refraction 

(table 19). Similarly, of the 6.0 percent whose 

actually have a refraction potential of 20/20 or 

usual visual acuity in the left eye was 20/50 or 

better. An additional 22.6 percent are colrrectworse, 20.7 percent showed a refraction potenable to the 20/25 level (table 20). 

tial of 20/20. Hence 21.5 percent of those with 

The proportion of males with refraction 

this usual degree of defective visuals acuity 

potential of at least 20/20 (26 percent) is greater 

than the proportion of females (18 percent), 

10 
although the proportion of the population 

whose usual monocular acuity does not exceed 

20/50 is similar for both sexes. 

Refraction potential of at least 20/20 decreases substantially with age among those in the 

population age 4-74 years with this degree of 

defective visual acuity (20/50 or less, usual), 

from 32.8 percent among children and young 

adults 4-24 years to 11.8 percent among older 

adults age 55-74 years. In contrast, refraction 

potential of 20/40 through 20/25, but less than 

20/20, shows a slight increase with age from 52 

percent in the 4-24-year-old group to 57 percent 

in the oldest age group. 

The 6.2 percent of the population age 4-74 

years with usual monocular acuity no better 

than 20/50 include about 0.8 percent testing 

20/200 or less in the eyes.8 The proportion in 

the population with one or both eyes “legally 

blind” (as used here, not correctable to 20/200) 

on the basis of central visual acuity (but not 

including those with sufficient visual field limitation also to be so considered) is approximately 

0.2 percent, as determined with the refraction 

retinoscopy done in this national survey (table 

20). 

On spherical refraction or retinoscopy, 50.7 

percent of those persons with one or both eyes 

testing less than 20/50 with usual correction, if 

any, reached their maximum refraction potential 

with the addition of some degree of negative 

spherical power, 46.9 percent with added positive spherical power, and 2.4 percent with no 

change. Maximum refraction potential was 

reached for 63.1 percent of these persons within 

a range of +1.5 diopters of additional spherical 

power. Among persons 4-54 years of age, relatively more are correctable to 20/20 with the 

addition of negative than positive spherical lens 

power; among older persons age 55-74 years, the 

maximum refraction potential is more likely to 

be reached with the addition of some positive 

than with some negative spherical lens power, a 

finding consistent with the apparent increase in 

myopia among younger persons and hyperopia 

among older persons evident from the correction 

in their present glasses or contact lenses. These 

associations are generally similar for the right 

and left eyes (tables 20 and 21). 

The additional spherical lens power needed 

for these persons (usual visual acuity of 20/50 or 

less) to reach their maximum refraction potential is generally similar for both eyes (table 22). 

For those with at least one eye correctable to 

20/20, 13.4 percent out of a possible 14.7 

percent required the same additional spherical 

lens power for each eye, and all possible (14.6 

percent) required added spherical power for the 

two eyes that differs by no more than 1.5 

diopters. Among persons whose monocular visual acuity could not be corrected to 20/20, 79.7 

percent required the same additional spherical 

lens power to realize the maximum refraction 

potential of their right and left eyes, and for 

93.7 percent the power required differs by no 

more than 1.5 diopters. 

A comparison of the spherical equivalence of 

the glasses or contact lenses worn by these 

persons with the spherical equivalence of the 

lens system determined on retinoscopy to be 

required for maximum visual acuity is shown in 

tables 23 and 24. More than two-thirds (68.6 

percent) of the population age 25-74 years have 

the same type (negative, positive, or zero) of 

correction; and, of these, more than two-thirds 

are of approximately the same power in their 

present glasses as that determined with retinoscopy. An estimated 13.3 percent with a negative 

spherical lens equivalency (correction for 

myopia) in their present glasses really need a 

positive spherical lens equivalency (correction 

for hyperopia) for their best visual acuity (as 

determined in retinoscopy); 9.7 percent with a 

positive equivalency should have a negative 

spherical equivalency. 

Maximum Visual Acuity 

Age and sex.-Nearly three-fourths (74.0 

percent) of the civilian noninstitutionalized population 4-74 years of age in the United States 

have a maximum distance visual acuity or 

refraction potential of at least 20/20 in their 

better eye as determined in this survey (figure 5 

and tables 25 and 26). These estimates are based 

on findings of usual and best corrected visual 

acuity from the Health and Nutrition Examination Survey of 1971-1972 among a national 

probability sample of examinees of whom about 

one-third (37 percent) were originally tested 

wearing their glasses or contact lenses and the 

remaining 63 percent without correction8 

11 
60 

5 

ti 40 

: 

20 

0 

20115 20120 20125 20130 20140 20/50 20170 20/60 20/100 

0, 

WOM 

ACUITY LEVEL ISNELLEN RATIO1 

Figure 5. Percent of population age 4-74 years reaching specified visual acuity levels for maximum vision in the better eye: 

United States, 1971-1972 

For only the 3.3 percent whose usual better eye 

acuity is 20/50 or less, the best corrected acuity 

was determined through retinoscopy or estimated in spherical refraction. With retinoscopy 

or spherical refraction, of course, a substantial 

number of the 23.9 percent whose usual better 

eye acuity is from 20/25 through 20/40 could 

be expected to be improved to the 20/20 level. 

Consequently this 74.1 percent will be an 

underestimate of the proportion in the population age 4-74 years whose refraction potential or 

maximum visual acuity in the better eye is at 

least 20/20 with best correction. 

The prevalence of a refraction potential no 

greater than 20/50 in monocular distance acuity 

of the better eye (with best correction) among 

the U.S. population age 4-74 years is 1.6 

12 

percent, and 0.2 percent are unable to reach the 

20/70 level, even with best correction. 

Males age 4-74 years tend to have somewhat 

greater refraction potential than females do. The 

proportion of males with potential better eye 

acuity (with best correction) of at least 20/20, 

as estimated here, is 76.2 percent compared with 

71.5 percent among females age 4-74 years; the 

proportion with refraction potential no better 

than 20/50 is 1.3 for males and 1.9 percent for 

females (figures 6 and 7). Less than 0.2 percent 

of males (compared with 0.5 percent of females) 

have a refraction potential no greater than 20/80 

in their better eye. 

Across this 4-74-year age range, the proportion in the population with refraction potential 

in the better eye (with best correction) of at 

least 20/20 increases steadily from 31.2 percent 

at age 4-5 years to a maximum of 89.1 percent 

among young adults age 18-24 years, levels off, 

then declines abruptly after age 45 years to 32.9 

percent in age 65-74 years. This age trend in 

refraction potential of at least 20/20 is similar 

for males and females. However, the proportion 

of males with this degree of potential exceeds 

that of females, except at age 25-34 years and 

65-74 years, where the differences are small 

enough to be due to sampling variability ‘alone. 

The prevalence of a refraction potential of 

20/50 or less in the better eye (with best 

correction) reaches a maximum of 8.5 percent in 

the oldest age group, for both sexes age 65-74 

years, 7.4 percent for men and 9.4 percent for 

women. 

The extent to which the usual visual acuity 

of the U.S. population could be improved is 

clearly indicated in the reduced proportion of 

the population whose refraction potential is 

20/50 or worse (from 3.3 percent to 1.6 

percent) and is indicated to a lesser extent iin the 

increased proportion with refraction potential of 

20/20 or better (from 72.8 percent to 74.0 

percent)8 (table 26). If the refraction potential 

of those with usual visual acuity between 20/40 

and 20/25 had been determined in this study, 

the increase in the proportion with refraction 

potential of at least 20/20 would be substantially greater. The improvement over their usual 

visual acuity is most pronounced at age 65-74 

years where the proportion with defective acuity 

of 20/50 or worse is decreased by 5.6 percentage 

points when the refraction potential is ‘deter- 
60 r 

ml5 2om 20/25 2onLl 2u/40 20/50 20/70 zimo ZJ/lOO 

or or 

more WOrr 

ACUITY LEVEL (SNELLEN RATIO1 

Figure 6. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the batter eye by sex: United States, 

1971-1972 

4.5 6.11 12.17 18.24 25.34 3644 45.54 55.64 65.74 

AGE IN YEARS 

Figure 7. Percent of population with maximum distance vision of 20/50 or worse in the batter eye by age and sex: United States, 

1971-1972 

13 
mined. The least improvement is found at age 

4-5 years and 35-44 years where the decrease in 

the proportion with defective visual acuity 

(20/50 or worse) is 0.5 and 0.6 percentage point, 

respectively. The difference between the proportions with maximum potential and usual visual 

acuity of 20120 or better at age 4-74 years 

ranges from 0.0 to 1.9 percentage points with no 

age trend noted. 

The pattern of improvement in refraction 

potential over usual visual acuity noted above 

for the total population is present for both 

males and females. No difference in the magnitude of increased visual acuity between the sexes 

is evident. 

Race.-Black persons age 4-74 years tend to 

have poorer maximum visual acuity or refraction 

potential, as estimated in this study, than white 

persons in the United States have (figure 8). 

Two-thirds (66.7 percent) of the Black population have a refraction potential in the better eye 

of at least 20/20 compared with 74.7 percent of 

the white population; 2.3 percent of Blacks 

compared with 1.5 percent of white persons 

could not read above the 20/50 level. The 

number of persons of other races in the U.S. 

population, and hence in the sample, was too 

small to provide estimates of their visual acuity 

sufficiently reliable for publication. 

Across the age range in the stud’y, the 

1CO60 - 

50 - 

5 

E 

E 

40 - 

20 - 

16.24 2534 

AGE IN YEARS 

35-44 45-54 55.54 65.74 

White 

a Black 

Figure 8. Percent of white and Black population with maximum visual acuity of at least 20/20 in the better eye by age: United States, 

1971-1972 

14 
proportion with refraction potential of at least 

20/20 in their better eye is less and the 

proportion unable to exceed the 20/50 level is 

greater, in general, among Black than among 

white persons. The greatest racial difference in 

refraction potential is evident among the 

youngest and oldest age groups-under 12 years 

and 65-74 years. 

Among the preschool group age 4-5 years, 

only 13.3 percent of Black children compared 

with 33.9 percent of white children have a - 

refraction potential of at least 20/20 in their 

better eye; at age 6-11 years, 56.0 percent of 

Black children compared with 76.3 percent of 

white children, and at age 65-74 years, 19.8 

percent of Black adults compared with 34.2 

percent of white adults, reach that level with 

best correction. The racial differences in these 

rates in the three age groups are large enough to 

be statistically significant (at the 5-percent 

level). The racial differences in the proportion 

with potential of at least 20/20 acuity in the 

better eye for ages 12-64 years are also present 

but less pronounced. 

Defective visual acuity with refraction 

potential no greater than 20/50 in the better eye 

is more than 3 times more prevalent among 

Black than among white preschool-age children 

(3.9 percent compared with 1.1 percent) and 

more than twice as great among Black adults as 

among white adults age 65-74 years (17.4 

percent compared with 7.6 percent). In the most 

severely defective groups with refraction potential no greater than 20/400, which would include many of the “legally” blind, there are 

proportionately 4 times as many Black adults as 

white adults age 65-74 years. At age 18-64 years, 

there is less difference between the two racial 

groups in the prevalence of this degree of 

defective acuity, although the rates are generally 

higher among Blacks. 

This pattern of poorer refraction potential 

among BIacks than among white persons is more 

consistent among females than among males and 

in both sexes is most pronounced among the 

youngest group (4-5 years) and the oldest (65-74 

years). 

At age 65-74 years, both white and Black 

women show a slightly higher proportion with 

refraction potential of at least 20120 in the 

better eye than their respective male counter: 

parts; the proportion with refraction potential 

no greater than 20/50 is also slightly higher for 

white and Black women than for white and 

Black men, respectively. 

The improvement in visual acuity possible 

with best correction, over usual correction, is 

slightly greater for the Black than for the white 

population. The proportion with refraction 

potential (in the better eye) no greater than 

20/50 is 2.8 percent less than the percent 

showing this degree of defect with their usual 

correction among Black persons compared with 

the reduction of 1.6 percent among white 

persons 4-74 years of age. Across the age range 

in this study, the extent to which defective 

visual acuity in the population could be reduced 

with best correction is greater among Blacks 

than among white persons, except at age 6-11 

years. The greatest racial difference in this 

improvement is evident among the youngest 

and the oldest age groups. At age 4-5 years, 

there is a 3.2-percent decrease among Blacks in 

the proportion with this degree of defect compared with 0.1 percent among whites; at age 

65-74 years, the decreases possible are 10.2 

percent among Black adults and 5.2 percent 

among white. 

This pattern of racial differences in the 

extent of possible reduction of defective visual 

acuity is generally found among both males and 

females. 

Income.-There is a consistent relationship 

between the level of family income and the 

refraction potential of persons 4-74 years of age 

in the United States. The proportion with better 

monocular acuity of at least 20/20 with best 

correction increases with the size of the annual 

family income from 61.1 percent among those 

in families with annual incomes less than $5,000 

to 71.7 percent in the middle income brackets 

to 80.4 percent among those with annual incomes of $10,000 or more; the proportion with 

defective visual acuity of 20/50 or less decreases 

from 4.4 percent in the lowest income bracket 

to 1.4 percent for those with annual family 

incomes of $5,000-$9,999 and to 0.6 percent 

among those in the highest income bracket 

(table 27 and figure 9). 

The relationship between refraction potential and family income generally is similar among 

both males and females. Among U.S. males, the 

15 
Annual family income 

El 

Les than $5,000 

iJqj $5,000-$9,999 

•j $10.000 or more 

4-5 6.11 12.17 ’ 1844 45.54 55.64 65.74 

AGE IN YEARS 

Figure 9. Percent of population age 4-74 years with at least 20/20 maximum dk%aziisbn in the better eye Gy age and family income: 

United States, 1971-1972 

increase in the proportion with refraction potential of at least 20/20 in the better eye from the 

lowest to the highest income-level group is from 

65.3 to ,82.2 percent; the proportion with 

defective visual acuity whose potential does not 

exceed 20/50 decreases from 4.9 to 0.3 percent. 

Similarly, among females, the proportion with 

refraction potential of at least 20/20 increases 

from 58.1 to 78.5 percent; the proportion of 

those with defective visual acuity decreases from 

4.1 to 0.9 percent from the lowest to the highest 

income-level group. 

This pattern of association of refraction 

potential with income is generally consistent 

over the age range in this study but tends to be 

somewhat stronger among children and youths 

age 4-17 years and adults in the middle age 

groups (45-64 years). Among males and females, 

the proportion with refraction potential of at 

least 20/20 in the better eye is generally highest 

in the highest income-level group, and the 

proportion with refraction potential no greater 

than 20/50 is significantly higher among persons 

with annual family incomes less than $5,000 

than among the others. 

Among the white pop&&on, the association 

of refraction potential and family income shows 

a consistency similar to that for the total 

population. Among the Black population, this 

association is somewhat less consistent (figure 

10). 

The extent of improvement possible with 

best correction in the proportion with defective 

visual acuity of 20/50 or less in the better eye 

16 
20 

2 

% 10 

i? 

45 YEARS 

0 

Whim Black ’ 

18.44 YEARS 

Whita Black 

B-11 YEARS 20 

White Blzck 

12.17YEARS 

White 

White Black 

20 

45.54 YEARS 

RACE 

55.64 YEARS 

White Elrk 

RACE 

Annual fmilyincw 

Figure 10. Percent of white and Black population age 4-74 years with 20/50 or worse maximum distance vision in the better eye by age 

and family income: United States, 1971-1972 

17 
ranges from 1.1 percentage points in the highest 

income-level group to 3.2 percentage points in 

the lowest income group in the total population 

(table 28). This relationship between income 

and the extent of improvement in visual acuity 

with best correction generally continues across 

age and sex, although it is less consistent in the 

two largest racial groups. 

Geographic region.-Children and youths 6- 

17 years of age in the South generally have 

greater refraction potential than do those in the 

other three regions of the country. The proportion whose acuity in the better eye would be at 

least 20/20 with best correction (if any is 

needed) is greater at age 6-17 years in the South 

than elsewhere, and the proportion not correctable above 20/50 is somewhat less (table 29). 

This regional pattern in the distribution of refraction potential is consistent among boys but 

not among girls at age 6-11 years nor is it consistent among either boys or girls of age 12-17 

years. 

Among children 4-5 years of age and adults 

18-74 years of age, the regional differences in 

the distribution of refraction potential in the 

better eye are less consistent than those for 

school-age children or youths. However, the 

proportion of adults with refraction potential no 

greater than 20/50 is consistently lower among 

those in the Midwest than elsewhere across the 

45-74-year range of all adults; this trend is 

consistent among women and, generally, among 

men. 

In three of the four regions, the proportion 

of persons with refraction potential at least 

20/20 in the better eye is at amaximum of 85-87 

percent among younger adults age 18-44 years; 

in the South this maximum is reached earlier 

among youths age 12-17 years where the rate is 

comparable with that in the 18-44-year age 

range. From these maximal values, the proportion with refraction potential of at least 20/20 

decreases consistently with age until by age 

65-74 years, the proportion with that degree of 

visual potential in the better eye is reduced to 

between 29 and 37 percent in the four regions. 

This age-related trend in refraction potential is 

generally consistent among males and females in 

each of the four geographic regions. 

The proportion with defective visual acuity, 

refraction potential no better than 20/50 in the 

better eye, is at a minimum of less than l-2 

percent among children, youths, and adults 

(4-54 years of age) and at a maximum among 

the oldest age group (65-74 years) with rates 

ranging from 6 to 11 percent in the four 

geographic regions of the United States. 

Among preschool-age children 4-5 years of 

age, the proportion with refraction potential of 

at least 20/20 in the better eye is greatest in the 

South-42.7 percent-compared with rates ranging from 15.7 percent in the West to 36.5 

percent in the Midwest. The wide variability in 

these rates is probably partly due to differences 

in targets used for testing and the degree of 

cooperation obtained in the examination. .At the 

other end of the acuity scale, there was little 

evidence of any regional differences in the 

prevalence of defective visual acuity. The proportion of preschool-age children with refraction 

potential no better than 20/50 ranged from 

approximately 1 percent in the West and South 

to about 2 percent in the Midwest and Northeast. 

The regional pattern in the distribution of 

refraction potential among white persons in this 

country generally is similar to that described 

above for persons of all races combined but is 

somewhat less consistent for the Black population. Among the Black preschool-age children, 

the prevalence of refraction potential of at least 

20/20 is about the same-13.5 to 15.5 per 

loo-in all regions except the Northeast where 

the rate is lower (3.8 per 100). The higher 

prevalences of refraction potential of at, least 

20/20 (be.tter eye) among Black children. 6-11 

years of age are in the West (75.0 per 100) and 

South (64.8 per 100) and the lower rates are in 

the Northeast (48.7 per 100) and in the Midwest 

(33.3 per 100); in contrast, the higher rates for 

refraction potential of at least 20/20 among 

Negro youths 12-17 years of age are in the 

Midwest (82.7 per 100) and South (83.6 per 

loo), and the lowest rate is in the West (68.7 per 

100). 

At age 18-74 years there is little consistency 

in regional differences in the proportion of 

white or Black population with refraction potential of at least 20/20 (better eye). The proportion with refraction potential no greater than 

20/50 is consistently slightly lower in the ‘West 

and Midwest for Black adults 45-74 years of age; 

18 
the proportion with defective visual acuity is 

generally lower in the Midwest for white adults 

age 45-74 years. 

Regional differences in the extent of improvement possible in visual acuity of the 

population, with best correction over usual correction, show little consistency (table 30 and 

figures 11 and 12). Among 4-5-year-olds, only 

those in the South (all Black) appear to improve. 

The decrease possible in the proportion of 

6-17-year-olds . testing no better than 20/50 

ranges from 0 to 3 percentage points among the 

four regions, and no consistent regional differences are evident. 

Among adults 18-74 years of age, the possible decrease in the proportion with visual 

acuity 20150 or worse is greatest in the South 

and West. This regional pattern is generally 

consistent for white and Black persons, although 

differences among the regions are somewhat 

more pronounced for Black than for white 

persons. Within each geographic region, the 

decrease possible in the proportion with visual 

acuity no better than 20150 is greater among 

Black than among white persons. This possible 

improvement in visual acuity described for all 

persons 18-74 years of both sexes combined is 

somewhat less consistent when the population is 

further subdivided by race and sex. 

Population Size of Place of Residence 

There is no consistent pattern of differences 

in the distribution of refraction potential (better 

eye) by population size of place of residence for 

m- 6.11 YEARS 

0 

Northeast Midwest South WW 

20 45.54 YEARS 

0 

Northeast Midwest South West 

20 

r 

12-17 YEARS 20 r 18.44 YEARS 

q White 

q Slack 

Northeast Midwest South Northem Midwest south West 

20 55-64 YEARS 20 6574YEARS 

0 0 

Northeast Midwest South W%t Northeast Midwest South WBt 

REGION REGION 

Figure 11. Percent change in proportion of population reaching 20/20 level in the better eye on maximum over usual acuity by age, 

race, and region: United States, 1971-1972 

19 
6-l 1 YEARS 20 12.17 YEARS 18.44 YEARS 

q ,White 

Black 

Northeast Midwest Northeast Midwest South Northeast Midwest South West 

-20 r 45.54 YEARS .20 55.64 YEARS .20 65.74 YEARS 

Northeast Midwest South West Northeast Midwest South West Northeast Midwest South West 

REGION AEGIQN REGION 

Figure 12. Percent change in proportion of population reaching no better than 2O/5tJ level in the better eye on maximum over usual 

acuity levels by age, race, and region: United States, 1971-1972 

the U.S. population 4-74 years of age. Among 

persons living in urbanized areas, 73.4 percent 

have refraction potential of at least 20/20, 

compared with 74.3 percent in urban communities outside of urbanized areas and 74.1 

percent in rural areas. The proportion with 

refraction potential no greater than 20/50 is 

slightly higher among those in urbanized areas1.9 percent-than among those in other urban or 

rural areas (1.5 and 1.3 percent, respectively). 

The differences in rates are not large enough to 

be statistically significant nor is there a consistent pattern of differences by population size of 

place of residence across age, race, or sex (table 

31). 

The extent of improvement in visual acuity 

possible with best correction over usual correction (if any) is similar in each of the population 

size groupings. 

Am&-y 

Information on the main ancestry or national origin was obtained in the Household 

Questionnaire for each examinee whose race was 

not classified as Black by the census interviewer. 

From this, estimates of refraction potential for 

three of the larger minority groups including 

Spanish and Mexican American, Chinese and 

Japanese, and American Indians living off reservations have been obtained. Recent imm@ants 

20 
from Puerto Rico are included with those of 

Spanish ancestry. The sample size ‘is not large 

enough to provide estimates sufficiently reliable 

to assess ethnic differences in acuity. The 

population size and the refraction potential for 

these minority groups by their racial classification are shown in table 32. 

Of the three ethnic subgroups, the 

Orientals (Chinese and Japanese) have the lowest proportion with possible visual acuity at 

least 20/20 and also the lowest proportion with 

refraction potential no better than 20/50 in the 

better eye-similar to the findings with respect 

to their usual better monocular acuity.8 The 

extent of improvement in visual acuity with 

best correction appears to be slightly better 

among the Oriental group than among the other 

ethnic groups. However, because of the small 

number of persons reporting themselves (or for 

children whose parents reported them) to have 

such ancestry in relation to the size of the 

sample, the precision of the national estimates 

of both usual visual acuity and refraction potential is below the level usually published in this 

series, and relatively large differences in prevalence rates probably reflect sampling variability 

alone, rather than any actual ancestry or ethnic 

differences in visual acuity. 

Motility-Maximum Acuity 

An estimated 62.0 percent of the population 

4-74 years of age with manifest strabismus 

(tropia) have refraction potential of at least 

20/20 in their better eye compared with 72.8 

percent of those with phoria and 74.5 percent 

of those with no evidence of either tropia or 

phoria (table 33). The prevalence of defective 

visual acuity (refraction potential no greater 

than 20/50 in the better eye) in the 4-74-year 

age range is 3.7 percent among those with manifest strabismus, 1.0 percent among those with 

phoria, and 1.6 percent among those with neither 

type of eye muscle imbalance. 

Children and adults 4-54 years of age with 

manifest strabismus have less refraction potential than those with phoria or those with neither 

type of motility problem have. In the oldest 

age groups (55-74 years), this pattern is reversed, 

although the differences in the proportions with 

‘good (20/20 or better) or poor (20/50 or worse) 

potential among those with or without motility 

defects are not large enough to be significant. 

The contrast between the refraction potential of those with and without manifest strabismus is greater among females than among males. 

The proportion with refraction potential of at 

least 20/20 among those with manifest strabismus is 17.1 percent less than among those 

without this type of eye muscle imbalance for 

females compared with only 4.5 percent less for 

males. The corresponding differences in the 

proportion with refraction potential no greater 

than 20/50 is 3.1 percent for females and 0.4 

percent for males. 

The association between the level of refraction potential and the presence or absence of 

strabismus described above for the total population and for males and females separately 

generally is consistent over the age range for the 

white and Black populations. 

Medical History 

Wearing giasses.- An estimated 103.4 million 

(58.9 percent) persons 6-74 years of age in the 

civilian noninstitutionalized population of the 

United States have ever worn glasses or contact 

lenses (table 34). Of those 12-74 years of age 

(65.9 percent of whom have ever worn corrective lenses), 0.6 percent have worn only contact 

lenses, 62.5 percent have ever worn only glasses, 

and 2.8 percent have ever worn both contact 

lenses and glasses. Of those 6-74 years of age 

who have ever worn corrective lenses, 88.9 

percent, or 92.0 million, still wear them. In all, 

52.4 percent of the U.S. population 6-74 years 

of age presently wear such lenses all or part of 

the time. These estimates are based on the 

answers given by the child’s parents in the 

Medical History Questionnaire, Ages 6-l 1 Years 

and by the examinee in the Medical History 

Questionnaire, Ages 12-74 Years as administered 

in the Health and Nutrition Examination Survey 

of 1971-1974. No such questions were asked in 

the medical histories for children under 6 years 

of age. 

The national estimates on trouble seeing and 

the use of eyeglasses from the medical history 

as shown in tables 34 and 34A are based on find21 
ings from the Health and Nutrition Examination 

Survey of 1971-1974 rather than limited to th’e 

1971-1972 period for which the eye examination 

findings from that survey are also available. Thle 

national probability sample for the 1971-1974 

period is about twice the size of the national 

probability sample for the 1971-1972 period 

and hence provides more reliable national estimates, although the findings from .this part of 

the two samples are generally similar. (The comparability of the estimates from the two samples 

is examined in appendix I.) 

The proportion of persons indicating they 

have ever worn glasses or contact lenses increases 

with age from 14.0 percent among children 6-l 1. 

years of age to 96.7 percent among the oldest 

adults ages 65-74 years. Contact lenses are more 

likely to have ever been used by younger adults 

18-24 years of age (8.0 percent) and least likely 

to have ever been used by the oldest adults in 

the study (0.5 percent at age 65-74 years). The 

proportion of the population presently wearing 

glasses or contact lenses increases from 11.9 

percent at age 6-11 years to 94.6 percent at 

65-74 years of age. 

Relatively more females than males age 6-74 

years have ever worn or are still wearing corrective lenses (the respective percentages are 52.5 

percent of males compared with 64.9 percent of 

females who have ever worn corrective lenses 

and 46.7 percent for males compared with 57.8 

percent of females still wearing glasses or contact lenses all or part of the time). 

Among children and young adults age 6-24 

years, the proportion of females ever having 

worn corrective lenses increases with age more 

rapidly than for males. From 6-l 1 years through 

18-24 years the proportion ever having worn 

such aids increases 46.2 percent for females 

(from 15.8 percent to 62.0 percent) compared 

with 31.0 percent for males (from 12.3 percent 

to 43.3 percent). From 25 years on, the increase 

with age in the use of such aids rises slightly 

more rapidly among men than among women 

until by age 45 there is a negligible difference 

between the two sexes in the proportion who 

have ever worn them. The maximum increase in 

the use of corrective lenses occurs between 35 

and 54 years of age for both sexes. 

In the survey, medical history information 

was obtained on the extent and type of use 

made of corrective lenses. Among those who 

have ever worn glasses or contact lenses, more 

than half (52.6 percent) wore them all of the 

time; 90.3 percent, for reading or other close 

work; and 62.3 percent, for distance vision. 

Those who ever wore glasses (or, contact 

lenses) were asked at what age they had started. 

For children 6-11 years of age, the average age 

when they first wore them was 7.1 years. 

Among persons 12-74 years of age, 46.1 percent 

began wearing glasses by the age of 19 and 59.4 

percent by the age of 29. 

Black persons 6-74 years of age are less 

likely than white persons in the same age range 

in this country to presently wear or to h[ave ever -- 

worn corrective lenses. The proportion presently 

wearing them is 35.4 percent among Blacks and 

54.4 percent among white persons; 42.8 bercent 

of Black persons indicate they have worn corrective lenses at some time compared with 60.9 

percent of white persons. 

Among both racial groups, relatively more 

females than males wear or have ever worn 

corrective lenses; the proportion ever wearing 

them is 50.8 percent among Black females 

compared with 33.5 percent among Black males 

and 66.9 percent among white females compared with 54.6 percent among white males. The 

racial pattern is similar among those presently 

wearing such aids. 

Information on the extent and type of use 

made of these corrective lenses indicates that a 

greater proportion of the white population (61.4 

percent of males and 64.5 percent of females) 

wear corrective lenses for distance vision than do 

the Black population (51.6 percent of males and 

53.5 percent of females). 

Trouble seeing.- An estimated 55.9 percent 

of the population age 6-74 years has ever had 

trouble seeing; 11.1 percent indicated having 

had trouble seeing even when wearing glasses or 

contact lenses. Of those who at one time had 

trouble seeing, 94.0 percent visited a doctor 

about this problem, but only 3.5 percent ever 

missed school or work because of trouble seeing. 

More females than males (60.9 percent 

compared with 50.5 percent) have had trouble 

seeing, and more females have had trouble seeing 

even when wearing glasses or contact ‘lenses 

22 
(12.3 percent compared with 9.4 percent of 

males). Fewer Black males and females (36.1 

percent and 50.0 percent) have had trouble 

seeing than have had white males and females 

(52.1 percent and 62.5 percent). 

Relation to visual acuity.-Persons who do 

not wear corrective lenses (47.9 percent of the 

population 6-74 years of age) have slightly 

better usual monocular acuity than those who 

wear glasses or contact lenses but have no 

trouble seeing with them (45.7 percent of the 

population), but both groups have significantly 

better vision than those who indicate they do 

have trouble with their vision even while wearing 

glasses or contact lenses (6.4 percent of the 

population) (figure 13). The respective proportions with usual acuity of at least 20/20 in the 

better eye are 77.0 percent, 73.0 percent, and 

54.7 percent; 3.5 percent, 2.4 percent, and 8.5 

percent, respectively, have usual acuity no better 

than 20/50 (tables 35, 37, 39, and 41). The 

refraction potential, as determined in this survey, is somewhat better than the usual acuity for 

each of the three groups (tables 36, 38,40, and 

42). Approximately 1 percent more would be 

able to see at the 20/20 level with best correction (an underestimate, as previously indicated 

in the section, “Maximum Visual Acuity”); the 

proportion not correctable above the 20/50 level 

is reduced, respectively, by 2.1 percent (no 

glasses), 0.6 percent (no trouble with glasses), 

and 3.9 percent (trouble with glasses). 

Relation to motility.-Those persons 6-74 

years of age found on examination to have 

manifest strabismus or some degree of phoria 

were more likely to indicate in history they had 

ever had trouble seeing (61.7 percent) than 

those who had no eye muscle imbalance defect 

(53.4 percent). This pattern is generally present 

across age, sex, and race (table 43). 

Children and youths with a vision problem 

on history and eye muscle imbalance were more 

likely to visit a doctor about their vision 

problem than were those of the same age with a 

vision problem but no evidence of eye muscle 

imbalance. Over the age of 17 years, this 

relationship is not generally present. 

Region.-Persons 6-74 years of age in the 

Northeast and Midwest, where the proportion 

with defective “usual visual acuity” is lower,8 

Usual acuity 

20/20 OR EEl7ER 

ximum awin/ 

Trouble No trouble 

with with 

!3l- gla*n 

Figure 13. Percent of population age 6-74 years with maximum 

or usual better eye monocular visual acuity of at least 20/20 

or no better than 20/50 according to whether or not they 

wear glasses or have trouble seeing with them: United States, 

1971-1972 

are also more likely to have ever had trouble 

with their vision, to have visited a doctor about 

the trouble, and to have ever worn glasses or 

contact lenses than are persons of this age in the 

South and West (table 44). This regional pattern 

is found generally among men and women and 

among white and Black persons across the age 

range. 

23 
20 TROPIA 20 PHORIA 

f-3 

E 

2 15 1963-1970 Physician 15 

> 

5 

B 1963.1970 Ortho-Rater 

2 -’ 10 10 

E 

$ 

2 

8 5 5 

AGE IN YEARS 

NOTE: Valuer for phonn. 1963~1970. me greater Ihan 5,. 

.- 

AGE IN YEARS 

Figure 14. Percent of U.S. children age 6-11 years in 1971-1972 and 1963-1965 and U.S. youths age 12-17 years in 1971-1972 and 

1966-l 970 with tropia or phoria as determined by examination or test 

Comparison With Previous Studies 

Mot&y.-National prevalence estimates of 

manifest strabismus (tropia) and some degree of 

phoria based on findings from the Health Examination Surveys of 1963-1965 among children 

6-11 years of age and of 1966-1970 among 

youths 12-l 7 years of age have been pub1ished.l O-l 2 As described, the identification of 

manifest and latent strabismus was made by the 

examining physician and a determination of the 

degree of phoria as part of the vision testing 

with standard commercial instruments (Master 

Ortho-Rater) done by the examining dentistsa* 

in each of the two previous surveys. 

The prevalence rates of manifest and latent 

strabismus among U.S. children and youths as 

determined from the ophthalmology examination in the 1971-1972 survey are higher than the 

corresponding rates from the physician’s examination and the Ortho-Rater tests in 1963- 

1965 among children and in 1966-1970 among 

youths (figure 14). From the present HANES 

study, the prevalence of tropia was estimated as 

3.7 .per 100 among U.S. children age 6-11 years 

and 4.8 per 100 among U.S. youths age 12-17 

aThe dental examiners were selected to do this part 

of the examination because of operational considerations (space limitations in the mobile examination 

centers) and because it was felt their professional 

background would add to the quality of the way in 

which the test was administered. 

24 

years compared with rates of 2.4 per 100 ‘among 

U.S. children from the 1963-1965 study and 3.4 

per 100 among U.S. youths from the 19616-1970 

study. The prevalence of phoria from the 1971- 

1972 HANES study is 15.9 per 100 U.S. 

children and 15.6 per 100 U.S. youths co:krpared 

with the respective rates of 4.3 (physician’s 

examination) and 14.6 (Ortho-Rater test) per 

100 children in 1963-1965 and 0.5 (physician’s 

examination) and 12.0 (Ortho-Rater test) per 

100 youths in 1966-1970. In both of the earlier 

surveys, the physician recorded the presence of 

only the most significant lateral phoria deviations; the Ortho-Rater tests permitted identification of all those with deviations of 5 prism 

diopters or more, the critical level frequently 

used in screening programs as the basis for 

referral for care or further study. 

The increase in these rates between the 

present and previous national Health Examination Surveys probably reflects primarily the 

differences in methodology or criteria bletween 

the respective points in time for children or 

youths rather than any real increase in prevalence of the conditions among either of these 

two age groups. Despite differences in survey 

methods, the prevalence of tropia increased with 

age and that of phoria decreased in both the 

present and earlier national studies. Motility 

status of adults was not determined in the initial 

Health Examination Survey of 1960-1962. 

Information on the prevalence of (manifest) 
strabismus has been published from two largescale community studies-the Orinda Study 

among more than 4,000 elementary school 

children of California in 1954-1956r s and the 

Tecumseh Community Health Study in 1959- 

1960 among more than 8,600 persons age 6 

years and over (88 percent of the total population in that area).l4 

In the Orinda Study from the screening by 

teachers and nurses among California children in 

grades 1-6, 4.8.percent were referred for further 

study because of inward or outward deviation of 

the eyes indicating possible manifest strabismus. 

This is somewhat greater than the rates for 

definite tropia of 3.7 per 100 from the 1971- 

1972 National Health and Nutrition Examination Survey and 2.4 per 100 from the 1963-1965 

National Health Examination Survey among 

U.S. children 6-11 years of age which might be 

expected since the determinations of tropia in 

both national surveys were made from more 

thorough eye examinations. 

--- - _. 

Among persons 6 years of age and over in 

the Tecumseh community, 1.8 per 100 had 

definite (manifest) strabismus and 1.3 per 100 

suspect (manifest) strabismus, somewhat lower 

than the U.S. estimates from the present national study of 3.7 per 100 among the U.S. 

population l-74 years of age. 

Best corrected acuity.-Measurements of 

best corrected acuity in the better eye were 

obtained in 1973-1975 among the still-living 

members of the Framingham (Massachusetts) 

study population, who had been under investigation for coronary disease risk factors since 1948 

and who were in 1973-1975 age 52-85 years.’ 5 

Visual acuity was measured using methods generally similar to those in the national survey. 

The screening examiner in the Framingham Eye 

Study used an A0 Projectoscope and wall screen 

in a room with shades drawn and all lights off, 

except for a small light to the side and behind 

the examinee. The chair (head rest) for the 

examinee was 10 feet from the wall screen with 

projected letters set to a 20-foot equivalent. If 

distance glasses were worn, acuity was tested 

with them. Acuity was generally recorded as the 

smallest complete line of letters read correctly, 

in contrast to the one letter misallowed at the 

recorded acuity level in the national study. If 

acuity for an eye was found to be 20/25 or 

worse, the eye was retested using a pinhole. If 

visual acuity was 20/30 or worse (including the 

pinhole attempt at improvement) the examiner 

completed a manifest refraction using either the 

prescription for existing glasses or retinoscopy as 

a base, in contrast to the national survey in 

which retinoscopy or refraction was done only 

on those whose usual acuity was 20/50 or less. 

The visual acuity level findings among persons 52-74 years of age from the Framingham 

study and the national estimates for the U.S. 

civilian noninstitutionalized population 45-74 

years of age based on the HANES findings are 

summarized in table A. 

As would be expected, the proportion reaching the acuity levels of 20/25 or better is 

significantly greater among the Framingham 

group, both men and women, than those from 

the national study. The differences are greater at 

age 65-74 years than among those younger, 

probably because the national estimates included persons 45-51 years of age whose acuity 

could be expected to be somewhat better than 

those age 52-64 years. Less difference between 

the Framingham and national study findings are 

evident if comparison is made for the proportion 

testing 20/40 or better in both studies to partially 

compensate for the difference in cutoff point 

used for refraction and retinoscopy in the two 

studies. However, even with this, the Framingham group does appear to have somewhat better 

acuity than that shown in the estimates for the 

U.S. adult population from the present national 

study. Whether this is merely a reflection of 

regional differences in acuity within the U.S. 

population or some differences in testing methods is not readily evident. 

Rej?active status. -The spherical and cylindrical power and axis deviation in the refractive 

lenses worn by the examinee were measured in 

the 1966-1970 Health Examination Survey 

among the national probability sample representative of the civilian noninstitutionalized 

population of youths age 12-17 years at the 

midsurvey point in time.1 1 

National estimates of the percent distribution of the spherical power, cylindrical power, 

axis deviation, power of the lens, and approximate actual spherical equivalence of the lens 

system in the glasses or contact lenses of youths 

from the earlier national survey are shown in 

25 
Table A. Percent distribution of best corrected visual acuity in the better eye as determined for U.S. adults in 1971-1972l and in the 

Framingham Eye Study in 1973-19752 

Acuity level and sex 

All levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 100.0 100.0 100.0 

Both sexes 

20/I O-20125 .................................................................................. .. 98.4 85.6 91.9 62.1 

20130.20140 .................................................................................... 0.9 12.3 5.6 29.4 

20/50-20170.. .................................................................................. 0.5 1.9 1.4 6.7 

2O/BO-201100 .................................................................................. 0.1 0.1 0.1 0.7 

201200 or worse.. ............................................................................ 0.1 0.1 1 .o I.1 

Men - 

20/10-20125.. .................................................................................. 

20/30-20140 .................................................................................... 

20/50-20170.. .................................................................................. 

20/80-20/I 00 .................................................................................. 

201200 or worse.. ............................................................................ 

Women 

2011 O-20125.. .................................................................................. 

20/30-20140.. .................................................................................. 

20/50-20170.. .................................................................................. 

2oiao-201100 .................................................................................. 

20/200 or worse.. ............................................................................ 

Both sexes ,,...............,.......................,.........,................... 

Men ................................................................................................. 

Women ............................................................................................ 

1973-I 975 1973-1975 

Framingham United States Framingham 

52-64 years 65-74 years 

1971-1972 

United States 

65-74 years 

98.0 

0.9 

0.9 

0.2 

98.6 

1.0 

0.3 

0.1 

Percent distribution 

85.9 95.3 61.3 

11.9 3.1 31.3 

2.2 0.6 6.2 

0.0 0.3 0.5 

0.0 0.6 0.7 

84.9 

13.0 

1.7 

0.3 

0.1 

89.5 

7.3 

1.9 

1.3 

62.5 

28.1 

7.2 

0.7 

1.6 

Number 

1,293 1,423 786 1,658 

573 691 318 815 

720 732 468 a43 

‘National estimates for the U.S. civilian noninstitutionalized adults 45-74 years of age based on findings from the ophthalmology 

examination in the Health and Nutrition Examination Survey of 1971-1972. 

2Followup study in which the still-living members of the Framingham, Mass., study population, who have been under investigation 

for coronary risk factors since 1948, were given an eye examination (see reference 15). 

tables 45-47 along with comparable data for this for myopia in the lenses used, among youths 

age group from the present study. wearing glasses or contact lenses, that is substanThe differences between the national esti- tially less in the present than the previous 

mates of the distribution of spherical power and national survey. The proportion with that (degree 

axis deviation in the glasses or contact lenses of correction (spherical equivalence) is 20 perworn at the time of the two national studies are cent in the 1966-1970 national survey compared 

well within the limits of sampling variability. with 7 percent in 

However, the sizable differences between the 

the 1971-1972 national 

surveys. Since measurement of uncorrected 

two studies in the distribution of cylindrical acuity for those wearing glasses was not done in 

power, in particular those with no cylindrical the present study, it is not possible to determine 

correction in their lenses, result in national how much, if any, of this may be due to 

estimates of the proportion with lens power or differences in the distribution of uncorrected 

spherical equivalence of more than 5 diopters visual acuity or the degree to which acuity is 

26 
corrected with lenses at the two points in time. 

It is likely that most if not all of this decrease in 

the proportion with strong correction represents 

differences in lensometer measurements of cylindrical power between the two studies rather 

than any real change with time. 

Wearing glasses.-Information on ever wearing glasses or contact lenses was obtained in the 

medical history in the Health Examination 

Surveys of 1960-1962 among adults, 1963-1965 

among children, and 1966-1970 among youths 

in a manner similar to that in the present 

national survey. Findings from these previous 

surveys indicate that the proportion of adults 

wearing corrective lenses was greater in 1971- 

1972 than in 1960-1962; the differences were 

greatest among younger adults 18-34 years of 

age and least among the older population, those 

55 years and over (figure 15). Proportionately 

more youths at the time of the 1966-1970 

Health Examination Survey indicated they wore 

corrective lenses than in the present Health and 

Nutrition Examination Survey, while the differences in the practice among children between 

1963-1965 and 1971-1972 are negligible. 

In answer to questions in the medical history 

regarding trouble seeing even with glasses or 

contact lenses, proportionately fewer young 

adults age 18-24 years in the present study 

indicated they had such trouble than in 1960- 

1962; from age 35 years on, slightly more have 

I 0 1966.1970 

-I__- 19m19S2 

1971.1972 

A 

I I I I 

20 40 60 90 

AGE IN YEARS 

Figure 15. Percent of U.S. population wearing glasses or contact 

lenses by age in 1971-1972 compared with percent in 1960- 

1970 

such trouble now than previously (figure 16). 

Questions were asked in the Health Examination 

Survey among youths in 1966-1970 regarding 

the need for glasses but not regarding trouble 

seeing with those they had, and hence the 

findings from the earlier study are not comparable to these findings from the present study. 

20 

I r TROUBLE SEEING WITH GLASSES q 1971.1972 

18.24 25.34 35.44 45.54 55S4 6574 

AGE IN YEARS 

Figure 16. Percent of adults age 18-74 years ever wearing glasses who have trouble seeing with them: United States, 1971-1972 and 

1960-1962 

27 
SUMMARY 

This report contains national estimates on 

refraction status, refraction potential or maximum corrected visual acuity, andl motility 

defects among the civilian noninstitutionalized 

population age 4-74 years in the United States 

with some limited motility data for children l-3 

years of age. These estimates, based on findings 

from the ophthalmologic examination in the 

Health and Nutrition Examination Survey of 

1971-1972, are analyzed with respect to age, 

sex, race, ancestry, region, population size of 

place of residence, annual family income, and 

responses to medical history questions on eye 

problems and use of glasses. 

For the first 35 examination locations of the 

Health and Nutrition Examination Survey in 

1971-1972, a national probability sample of 

14,147 persons ages 1 through 74 years was 

carefully and scientifically selected to represent 

the 192.7 million in the civilian noninstitutionalized population of that age in tlhe United 

States at midsurvey time. The 10,126 persons 

who came in for examination represent 72.8 

percent of the sample persons selected when 

adjustments are made for the differential sampling rates used in the age-, sex-, and incomedefined population subgroups. Persons age l-74 

years were examined for motility defects; visual 

acuity, refraction status, and refraction potential 

measurements were obtained on the 9,263 examinees age 4-74 years; and comparable medical 

history on eye problems and use of glasses was 

obtained for those age 6-74 years. 

Principal findings from this study include: 

l More than 7.1 million, or 3.7 percent, of 

the civilian noninstitutionalized population age l-74 years in the United States 

have manifest strabismus or tropia, a 

disturbance of coordination of the extraocular muscles of the eyes retained on 

monocular and binocular viewing. 

0 An estimated 30.8 million, 16.0 percent, 

of the U.S. civilian noninstitutionalized 

population 1-74 years of age have latent 

strabismus or phoria, a tendency for one 

eye to deviate so as to look at a different 

image than the other eye looks at when 

binocular viewing is interrupted. 

l In all, an estimated 38 million, or 19.5 

percent, of the U.S. population age 1-74 

years have manifest or latent eye muscle 

imbalance. 

l More than one-half (52.4 percent), or an 

estimated 92 miIlion, of the U.S. population age 6-74 years wear corrective lenses 

(glasses or contact lenses) all or part of 

the time, according to medical history 

findings from the Health and Nutrition 

Examination Survey. 

0 Among the population age 4-74t years, 

the correction in their present glasses is 

about as likely to be for myopia (nearsightedness) as for hyperopia (farsightedness). These lens measurements were 

made for all examinees who brought 

their corrective lenses to the examination-78.2 percent of those 6-74 years of 

age who indicated on history that they 

wore glasses or contact lenses and 2.4 

percent of the 4- and 5-year-old examinees also wearing them at the time of 

the examination. 

l The proportion with a present correction 

for myopia increases with age among 

children from 30.2 percent at age 4-5 

years to a maximum of 87.2 percent at 

12-17 years of age, then consistently 

decreases to a minimum of 15.7 percent 

at age 65-74 years. 

l From pinhole tests (without using dilation) to estimate refraction potential, of 

the estimated 63.2 million persons, or 

34.7 percent of the U.S. population 4-74 

years of age, whose usual visual acuity 

with their own glasses or contact lenses 

if worn (or without, if not) is less than 

20/20 in either eye, 16.0 percent are 

able to reach the 20/20 level on retest 

with the use of the pinhole. 

l Using retinoscopy (following dilatation) 

among the 6.2 percent with usual monocular acuity 20/50 or worse, 21.5 

percent show refraction potential of 

28 
20/20, and an additional 22.6 percent 

are correctable to the 20/25 level. 

Refraction potential of at least 20/20 

decreases substantially with age among 

those whose usual visual acuity is 20/50 

or worse, from 32.8 percent among 

children and young adults age 4-24 years 

to 11.8 percent among older adults. 

Refraction potential with best correction 

(in the better eye) of at least 20/20 

among those with usual visual acuity 

20/50 or worse increases with age from 

31.2 percent among children age 4-5 

years to a maximum of 89.1 percent 

among young adults age 18-24 years, 

levels off, then declines abruptly after 

age 45 years to 32.9 percent in age 65-74 

years. 

This trend with age in refraction potential of at least 20/20 is similar among 

males and females. However, the proportion of males with this degree of potential exceeds that for females except at 

age 25-34 years and 65-74 years. 

Black persons age 4-74 years tend to 

have less refraction potential, as measured in this study, as well as somewhat 

poorer usual visual acuity than do white 

persons. 

l Refraction potential is found to increase 

with annual family income, an association stronger among the white than 

among the Black population. 

0 An estimated 58.9 percent of persons 

6-74 years of age have ever worn glasses 

or contact lenses, and 52.4 percent still 

wear them all or part of the time as 

reported on medical history. The proportion of the population presently wearing 

corrective lenses increases from 11.9 

percent at ages 6-11 years to 94.6 

percent at age 65-74 years. 

l An estimated 55.9 percent of the population age 6-74 years have ever had 

trouble seeing; 11.1 percent report having had trouble seeing even with their 

glasses or lenses. 

0. Of those who at one time had trouble 

seeing, 94.0 percent visited a doctor 

about the problem, but only 3.5 percent 

ever missed school or work because of 

trouble seeing. 

Comparisons with previous findings among 

U.S. adults, children, and youths from the 

Health Examination Surveys of 1960-1970 are 

included, as well as comparisons with published 

findings from several of the more geographically 

limited studies. 

000 

29 
REFERENCES 

‘National Center for Health Statistics: Origin, program, and operation of the U.S. National Health Survey. 

ViTituZ and Health Statistics. PHS Pub. No. lOOO-Series 

l-No. 1. Public Health Service. Washington. U.S. Government Printing Office, Aug. 1963. 

*National Center for Health Statistics: Plan and 

initial program of the Health Examination Survey. Vital 

and Health Statistics. PHS Pub. No. lOOO-Series l-No. 4. 

Public Health Service. Washington. U.S. Government 

Printing Office, July 1965. 

3National Center for Health Statistics: Cycle I of the 

Health Examination Survey: Sample and response, 

United States, 1960-1962. Vital and Health Statistics. 

PHS Pub. No. 1 OOO-Series 1 l-No. 1. Public Health Service. 

Washington. U.S. Government Printing Office, Apr. 

1964. 

4National Center for Health Statistics: Plan, operation, and response results of a program of children’s 

examinations. Vital und Health Statistics. PHS Pub. No. 

1000~Series l-No. 5. Public Health Service. Washington. 

U.S. Government Printing Office, Oct. 1967. 

5National Center for Health Statistics: Plan and 

operation of a Health Examination Survey of U.S. 

youths 12-17 years of age. Vital and Health Statistics. 

PHS Pub. No. lOOO-Series l-No. 8. Public Health Service. 

Washington. U.S. Government Printing Office, Sept. 

1969. 

6National Center for Health Statistics: Plan and 

operation of the Health and Nutrition Examination 

Survey, United States, 1971-1973. Vital and Health 

Statistics. Series I-Nos. 10a and lob. DHEW Pub. No. 

(HSM) 73-1310. Health Services and Mental Health 

Administration. Washington. U.S. Government Printing 

Office, Feb. 1973. 

‘National Center for Health Statistics: A study of the 

effect of remuneration upon response in the Health and 

Nutrition Examination Survey, United States. Vital and 

Health Statistics. Series ~-NO. 67. DHEW Pub. No. 

(HRA) 76-1341. Health Resources Administration. 

Washington. U.S. Government Printing Office, Oct. 

1975. 

*National Center for Health Statistics: Monocular 

visual acuity of persons 474 years, United States, 

1971-1972. Vital and Health Statistics. Serieq ll-No. 

201. DHEW Pub. No. (HRA) 77-1646. Health Resources 

Administration. Washington. U.S. Government Printing 

Office, Mar. 1977. 

gNewell, F. W.: Ophthalmology, Principles and Concepts. 2d ed. St. Louis. The C.V. Mosby Company, 

1969. 

1 ONational Center for Health Statistics: Eye examination findings among children, United States. Vital and 

Health Statistics. Series 1 l-No. 115. DHEW Pub. No. 

(HSM) 72-1057. Health Services and Mental Health 

Administration. Washington. U.S. Government ;Printing 

Office, June 1972. 

1’ National Center for Health Statistics: Refraction 

status of youths 12-17 years, United States. T<itul and 

Health Statistics. Series ll-No. 148. DHEW I?ub. No. 

(HRA) 75-1630. Health Resources Administration. 

Washington. U.S. Government Printing Office. Dec. 

1974. 

12National Center for Health Statistics: Eye examination findings among youths aged 12-17 years, United 

States. Vital and Health Statistics. Series 11-No. 155. 

DHEW Pub. No. (HRA). 76-1637. Health Resources 

Administration. Washmgton. U.S. Government Printing 

Office, Nov. 1975. 

13Blum, H. L., Peter, H. B., and Bettman, J. W.: 

Vision Screening for Elementary Schools. The Orindu’ 

Study. Berkeley. University of California Press, 11968. 

14Francis, T., Jr., and Epstein, F. H.: Studies of a 

total community, Tecumseh, Michigan, in International 

Conference on Comparability in Epidemiological 

Studies. Milbunk Mem. Fund Q. 43(2):333-42, Apr. 

1965. 

1 5Kahn, H. A., Leibowitz, H. M., Ganley, J. M., Kini, 

M. M., Colton, T., Nickerson, R. S., and Dawber,T. R.: 

The Framingham Eye Study. I. Outline and major 

prevalence findings. Am. J. Epid. 106(1):17-32, 1977. 

30 
LIST OF DETAILED TABLES 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

13. 

14. 

15. 

16. 

17. 

18. 

19. 

Prevalence rates and standard errors of tropia at age 1-74 years, by age, sex, and race: United States, IQ71 -1972 ....................... 

Prevalence rates and standard errors of tropia at age l-74 years, by annual family income, age, and sex: United States, 

1971-1972 .................................................................................................................................................................................... 

Prevalence rates and standard errors of phoria at age 1-74 years, by age, sex, and race: United States, 1971-1972.. ..................... 

Prevalence rates and standard errors of nystagmus at age l-74 years, by age, sex, and race: United States, 1971-1972.. .............. 

Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the spherical power of the 

lens for each eye and by age, with selected standard errors: United States, 1971-1972.. ....... I.. ......... .I ......................................... 

Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the cylindrical power of the 

lens for each eye and by age, with selected standard errors: United States, 1971-1972 ................................................................ 

Percent of lenses in the glasses or contact lenses of the population age 4-74 years, by the spherical and cylindrical power of the 

lens: United States, 1971-1972 ..................................................................................................................................................... 

Percent of lenses in the glasses or contact lenses of the population age 4-24 years, by the spherical and cylindrical power of the 

lens: United States, 1971-1972 ..................................................................................................................................................... 

Percent of lenses in the glasses or contact lenses of the population age 25-54 years, by the spherical and cylindrical power of 

the lens: United States, 1971-1972 ............................................................................................................................................... 

Percent of lenses in the glasses or contact lenses of the population age 55-74 years, by the spherical and cylindrical power of 

the lens: United States, 1971-1972 ............................................................................................................................................... 

Percent of lenses in the glasses or contact lenses of the population age 4-74 years, by sex and the power of the sphere or 

cylinder and by age and sex for negative and positive corrections: United States, 1971-1972.. .................................................... 

Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the axis deviation of the lens 

for each eye and by age, with selected standard errors: United States, 1971-1972 ....................................................................... 

Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 yean, by the spherical equivalence of 

the lens for each eye and by age, with selected standard errors: United States, 1971-1972 .......................................................... 

Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the power of the lens for 

each eye and by age, with selected standard errors: United States, 1971-1972.. ........................................................................... 

Percent distribution of population age 4-74 years, by monocular visual acuity on the pinhole test for those with less than 

20/20 usual visual acuity at each level of usual visual acuity: United States, 1971-1972 .............................................................. 

Percent distribution of population age 4-24 years, by monocular visual acuity on the pinhole test for those with less than 

20/20 usual visual acuity at each level of usual visual acuity: United States, 1971-1972 .............................................................. 

Percent distribution of population age 2544 years, by monocular visual acuity on the pinhole test for those with less than 

20/20 usual visual acuity at each level of usual visual acuity: United States, 1971-1972 .............................................................. 

Percent distribution of population age 45-74 years, by monocular visual acuity on the pinhole test for those with less than 

20/20 usual visual acuity at each level of usual visual acuity: United States, 1971-1972 .............................................................. 

Percent of population age 4-74 years with usual distance vision below 20/4Q reaching the 20/20 level in spherical refraction or 

retinoscopy, by the strength of the lens required for each eye and by age and sex, with standard errors for totals: United 

States, 1971-1972.. ....................................................................................................................................................................... 

34 

36 

37 

39 

41 

41 

42 

42 

43 

43 

44 

45 

45 

46 

46 

47 

47 

48 

49 

31 
20. Percent distribution of population age 4-74 years with usual distance vision less than 20/40, by maximum monocular visual 

acuity in spherical refraction or retinoscopy for those at each level of usual visual acuity and by age: United 

States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ................................................ 50 

21. Percent of population age 4-74 years with usual distance vision less than 20/40, by strength of added lens used and maximum 

visual acuity in spherical refraction or retinoscopy for each eye: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 

22. Number and percent of population age 4-74 years with usual distance vision less than 20/40 whose acuity was increased to 

20/20 in at least one eye and whose acuity was not increased to 20/20 in either eye, by strength of added lens used in spherical 

refraction or retinoscopy for maximum visual acuity in each eye: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 

23. Percent of lenses used in retinoscopy by type of spherical1 equivalence in added lens for maximum visual acuity among population age 25-74 years and type in present glasses or contac:t lenses: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . q......... 51 

24. Percent of lenses used in retinoscopy by spherical equivalence in added lens for maximum visual acuity among population age 

25-74 years and in present glasses or contact lenses: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 

25. Percent distribution and number of population age 4-74 ‘years by maximum visual acuity levels reached in the better eye with 

usual correction for those testing 20/40 or better and with additional correction on spherical refraction or retinoscopy for the 

remainder shown, by age, sex, and race, with standard errors: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 

26. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye1 and difference 

between this maximum and usual visual acuity, by age, ser:, and race: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 

27. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye,l by annual family 

income, age, race, and sex, with standard errors: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a . . . . . . . . . 58 

28. Difference between maximum and usual visual acuity levels in the better eye1 among population age 4-74 years, by annual 

family income, age, race, and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 

29. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye,l by region, age, race, 

and sex, with standard errors: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .I ,......... 66 

30. Difference between maximum1 and usual visual acuity levels in the better eye among population age 4-74 years, by region, 

age, race, and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........ 70 

31. Percent of population age 4-74 years reaching specified visual acuity levels for maximum distance vision in the better eye,l by 

size of place of residence, age, race, and sex, with standard errors: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 

32. Percent and number of population age 4-74 years reachin!g at least 20/20 and percent reaching no better than 20150 maximum 

visual acuity in the better eye,l by ancestry and race: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 

33. Percent of population age 4-74 years with maximum visual acuity of 20/20 or better and 20/50 or less1 with manifest 

strabismus, phoria, or noeye muscle imbalance, by age, sex, and race with standard errors: United States, 1971-1972................ 76 

34. Prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age lenses first born, 

among population 6-74 years, by age, race, and sex: Unitecl States, 1971-1974 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 

34A.Standard errors for prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age 

lenses first worn, among population 6-74 years, by age, race, and sex: United States, 1971-1974 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 

35. Percent of total population age 6-74 years who still wear glasses and percent distribution of their usual visual acuity levels in 

the better eye, by age and sex: United States, 1971-1972 ..,,............................................,............................................................ 89 

36. Percent of total population age 6-74 years who still wear glasses and percent distribution of their maximum visual acuity levels 

in the better eye,l by age and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 

37. Percent of total population age 6-74 years who wear glasses and have no trouble seeing with them and percent distribution of 

their usual visual acuity levels in the better eye, by age and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 

38. Percent of total population age 6-74 years who wear glasses and have no trouble seeing with them and percent distribution of 

their maximum visual acuity levels in the better eye,l by age and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 

lVisual acuity levels reached with usual correction for th,ose testing 20/40 or better and with additional correction on spherical 

refraction or retinoscopy for the remainder. 

32 
39. Percent of total population age 6-74 years who do not wear glasses and percent distribution of their usual visual acuity levels 

in the better eye, by age and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 

40. Percent of total population age 6-74 years who do not wear glasses and percent distribution of their maximum visual acuity 

levels in the better eye,l by age and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 

41. Percent of total population age 6-74 years who have trouble with vision even when wearing glasses and percent distribution of 

their usual visual acuity levels in the better eye, by age and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 

42. Percent of total population age 6-74 years who have trouble with vision even when wearing glasses and percent distribution of 

their maximum visual acuity levels in the better eye,l by age and sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 

43. Prevalence rates for selected medical history items among population age 6-74 years with and without eye muscle imbalance, 

by age,.sex, and race, with standard errors: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 

44. Prevalence rates for medical history findings pertaining to the eye among population age 6-74 years, by age, sex, race, and 

geographic region, with standard errors: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 

45. Percent distribution of lenses in the glasses or contact lenses of youths age 12-l 7 years, by the spherical or cylindrical power 

of the lens: United States, 1966-1970 and 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 

46. Percent distribution of lenses in the glasses or contact lenses of youths age 12-17 years, by the degree of axis deviation of the 

cylinder in the lens: United States, 1966-1970 and 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 

47. Percent distribution of lenses in the glasses and contact lenses of youths age 12-17 years, by the power and equivalence of the 

lens: United States, 1966-1970 and 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .... 102 

33 
Table 1. Prevalence rates and standard errors of tropia at age I-74 years, by age, sex, and race: United States, 1971-1972 

Tropia 

Tonal --T-i E IS0 I EXO I Hoer I Comitant lncomitant 

Stand- Stand- Stand- Stand- Stand- StandRate ard Rate ard Rate ard Rate ard Rate ard Rate ard 

error error error error error error 

Age, sex, and race1 

Both sexes Rate per 100 parsons and standard error 

All races, 1-74 years . . . . . . . . . . . . . . . . . . . . . . 0.24 2.1 0.24 0.6 0.11 2.1 

White ............................................................ 

Black ............................................................ 

All races, l-3 years.. ........................... 

White ............................................................ 

Black ............................................................ 

All races, 4-24 years.. ......................... 

White.. ...................... . ................................... 

Black ............................................................ 

All races, 2554 years.. ....................... 

White ............................................................ 

Black ............................................................ 

All races, 55-74 years.. ....................... 

White ............................................................ 

Black ............................................................ 

3.7 

- 

3.7 

3.3 

1.9 

1.9 

1.7 

3.3 

3.4 

2.9 

3.3 

3.3 

3.1 

6.1 

5.8 

6.9 

Male - 

All races, l-74 years.. .................... 3.0 

White ............................................................ 3.0 

Black ............................................................ 3.6 

All races, l-3 years.. ........................... 1.3 

White ............................................................ 1.5 

Black ............................................................ 0.6 

All races, 4-24 years.. ......................... 2.9 

White ............................................................ l 2.9 

Black ............................................................ 2.7 

All races, 25-54 years ......................... 2.1 

White ............................................................ l 1.9 

Black ............................................................ 3.8 

All races, 55-74 years.. ....................... 6.1 

White ............................................................ l 5.9 

Black ............................................................ l 9.0 

0.41 1.2 0.3 

0.43 1.3 

0.47 l 0.6 

1.29 l 1.3 

1.38 l 1.4 

1.02 l 1.1 

0.58 l 1.7 

0.66 l 1.9 

0.32 l 0.8 

0.38 l 0.8 

0.39 l 0.9 

0.63 l 0.1 

1 .oo +1.1 

0.97 l 1.1 

1.68 l 0.7 

0.60 ‘0.9 

0.57 l 0.9 

0.38 ‘0.2 

1.19 l 1 .2 

1.48 ‘I .4 

0.59 +0.3 

0.67 l 1 .4 

0.74 V.6 

1.13 ‘0.1 

0.51 l o .3 

0.55 l 0.3 

0.74 l 0.2 

1.48 l 0.7 

1.67 l o .7 

2.33 l 0.8 

0.09 

0.17 

0.05 

2.1 

“1.8 

*1.3 

- 

l 1 .3 

l 1.4 

0.29 

- 

0.29 

0.56 

1 .OB 

0.32 

0.12 

0.14 

0.07 

2.1 

- 

l 2.2 

l 1.2 

0.16 1.6 

0.15 1.5 

0.46 ‘1.8 

0.45 3.7 

0.53 3.7 0.80 1.4 0.29 3.4 

0.44 l 6.2 1.69 *0.4 0.16 l 4.0 

1.12 

1 .oo 

0.51 

0.57 

0.47 

0.32 

0.32 

0.79 

0.79 

0.81 

1.30 

0.32 ‘0.4 0.13 

0.13 

0.32 

1.7 

- - 

1.7 

l 1.9 

0.34 

0.38 

0.62 

0.10 l 0.8 

- 

l 1.0 

l 0.3 

0.82 

0.59 

0.03 

1.01 

0.29 

*I.9 0.56 

0.04 0.64 

0.80 

0.23 

l 2.0 

l 1.4 

l 0.9 0.43 

0.20 l 0.8 0.42 

1.08 l 2.2 1.28 

0.58 l 3.5 

0.42 l l l 1.3 0.64 l 3.4 

0.81 l l ‘0.2 0.08 l 4.6 

1.19 

1.30 

2.05 

0.26 2.0 0.26 

0.23 2.7 0.36 

1.10 l 0.3 0.21 

0.5 

l 0.3 

0.1 

l 0.3 

l 0.3 

l o .3 

l 0.3 

l 0.3 

l 0.3 

0.10 

0.28 

0.26 

0.33 

0.19 

0.13 

0.12 

0.58 

0.13 

1.16 l o .2 0.21 

089 l 0.6 0.32 

0.44 1.4 0.23 

0.51 1.3 0.25 

0.36 2.1 0.41 

0.23 2.3 0.30 

0.25 

0.11 

2.2 

2.9 

4.1 

0.30 

0.62 

0.48 0.83 

0,3 

l 0.3 

l 0.3 

‘0.1 

l 0.4 

‘0.4 

*0.7 

*I.6 

“0 ;a’ 

. ., 

l 0.6 

l 0.2 

l 0.2 

l o.o 

“0.8 

0.14 

0.04 

0.36 

0.25 

0.29 

0.12 

1 .18 

1.46 

0.29 

0.51 

1.9 

G 

1.7 

3.4 

l 0.1 

‘0.1 

l 0.3 

1.3 

0.36 

0.36 

0.11 

l 0.3 

‘0.5 

0.1 

0.6 

l o .o 

l 0.8 

‘0s~ 

‘0.3: 

E 

l 0.3 

‘0.0 

l 0.01 

0.39 

0.04 

0.11 

0.13 

0.03 

0.05 

0.29 

0.16 

0.13 

0.28 

0.30 

l 0.3 

l 0.2 

0.60 

0.08 

0.18 

0.20 

0.18 

0.40 

l 

l 

1.7 

l 

l 

0.36 

l o.o 

l o .4 

l 0.3 0.18 

l l 

3.6 0.69 

l l 

‘0.3 

‘1.4 

l 1.2 l 1.3 0.58 

l 1.4 0.64 

DO.1 0.08 

‘Totals include racas other than white and Black. 

34 
Table 1. Prevalence rates and standard errors of tropia at age I-74 years. by age, sex, and race: United States, 1971-1972-Con. 

Age, sex, and race1 

Female. 

Total Eso Exo Hyw Comitant lncomitant 

Stand- Stand- Stand- Stand- Stand- StandRate ard Rate ard Rate ard Rate ard Rate ard Rate ard 

error error error error error error 

Rate per 1 CKJ persons and standard error 

All races, 1-74 years.. ......... . .......... 4.3 0.45 

White ............................................................ 4.4 0.48 

Black ............................................................ l 3.1 0.95 

All races, 1-3 years.. ........................... 2.4 1.48 

White.. .......................................................... 

Black ....................... . .................................... 

2.3 1.42 

3.0 2.22 

All races, 4-24 years.. ......................... 3.7 0.66 

White ............................................................ 3.8 0.73 

Black ............................................................ ‘3.0 1.37 

All races, 25-54 years.. ....................... 4.3 0.56 

White ............................................................ 4.6 0.59 

Black ............................................................ l 2.5 1.00 

All races, 55-74 years.. ....................... 6.0 1.19 

White ............................................................ 5.6 1.25 

Black ............................................................ ‘5.4 2.09 

Tropia 

1.6 

C 

1.7 

+o .9 

*I .5 

l 1.3 

l 2 .2 

2.1 

2.2 

l 1 .5 

l 1 .3 

*1.4 

l 0.1 

“1.4 

“1.5 

“0.7 

- 

0.32 2.4 0.21 ‘0.7 0.15 2.5 0.38 “0.4 0.11 

0.34 2.3 0.26 l 0.7 0.16 2.6 0.41 

0.43 f2.1 0.67 l 0.2 0.08 l 1.6 0.72 

0.15 

0.51 

1.05 “0.5 0.37 “1.8 1.39 

0.92 ‘0.4 0.36 l 1.6 1.26 

1.96 l 0.9 0.66 +2.8 2.24 

0.45 “1.6 0.34 ‘0.6 0.25 2.3 0.56 

l 0.4 

‘0.6 

l 0.6 

l 0.6 

‘0.2 

‘0.4 

0.52 “1.6 0.35 

0.72 l 1.5 1 .lO 

l 0.7 

l 0.2 

‘0.5 

l 0.5 

l 0.1 

l 1.9 

1.5 

“0.5 

0.28 l 2.5 0.64 

0.14 ‘1 .l 0.49 

0.42 2.9 0.43 0.20 2.1 0.38 

0.48 2.9 0.43 

0.13 l 2.3 1.00 

0.23 2.2 0.44 

0.09 l 1 .5 0.95 

0.66 3.7 

l 3.1 

l 4.7 

0.77 0.49 ‘3.8 1.09 

0.95 

0.56 

0.69 

1.98 

0.32 l 3.3 1.26 

0.28 l 3.6 1.92 

l 0.2 

l 1.1 

‘0.4 

l 0.4 

l 0.1 

‘0.4 

‘0.4 

0.52 

0.66 

0.24 

0.20 

0.14 

1.09 

0.25 

0.28 

0.06 

0.33 

0.37 

‘Totals include reces other than white and Black. 

35 
Table 2. Prevalence rates and standard errors of tropia at age 1-74 years, bv annual family income, age, and sex: United States, 

Age and sex 

1971-1972 

cq-gq&q?jq-y 

II I I I 

. . ..- _~ 

Both sexes Rate per 100 persons Standard error 

All ages, 1-74 

years .................... 4.6 4.5 5.2 4.1 5.3 0.63 11 0.88 0.86 0.67 1.40 

1-3 years ................................ 2.6 2.6 1.7 3.7 

4-24 years.. ............................. 4.0 3.0 5.0 3.6 

25-54 years.. ........................... 4.4 6.5 5.5 3.2 

55-74 years.. ........................... 6.9 5.1 6.2 10.2 

Male 

All ages, l-74 

years .................... 3.9 4.8 4.4 3.3 

1-3 years.. ............................... 2.0 1 .o 1.2 3.5 

4-24 years.. ............................. 3.7 3.4 4.6 3.1 

25-54 years.. ........................... 3.0 5.9 3.6 2.3 

55-74 years.. ........................... 7.4 7.3 6.8 8.2 

Female 

All ages, 1-74 

years .................... 5.2 4.2 5.9 5.0 6.5 

l-3 years.. ............................... 3.3 4.1 2.3 3.9 

4-24 years.. ............................. 4.4 2.6 5.4 4.1 

25-54 years.. ........................... 5.7 6.8 7.2 4.2 

55-74 years.. ........................... 6.6 3.9 5.6 12.6 

2.43 

2.16 

2.36 

1.90 

1.11 2.33 

1.06 0.79 

1.37 0.56 

1.67 2.33 

1.09 0.77 

4.1 

6.6 

5.5 

3.9 

1.48 1.45 

0.67 II 0.85 

0.73 2.29 

1.21 2.48 

1.52 0.94 

1.03 0.70 

2.67 2.53 

3.76 

2.89 

3.68 

0.96 0.79 1.98 

3.3 

3.0 

6.8 

1.21 2.34 

1.02 0.89 

2.05 0.90 

2.23 3.92 

4.8 

9.7 

4.6 

3.27 

3.78 

2.97 

36 
Table 3. Prevalence rates and standard errors of phoria at age 1-74 years, by age, sex, and race: United States, 1971-1972 

Phoria 

Age, sex, and race1 

Both sexes 

~ 

Rate per 100 persons and standard error 

All races, I-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.0 1.84 2.1 0.33 13.8 1.74 “0.4 

15.9 

17.0 

3.3 

1.85 2.2 

2.68 *1.2 

0.91 0.2 

2.8 0.89 0.2 

5.1 2.25 0.2 

14.8 1.36 2.4 

White ...................................................................................... 

Black ...................................................................................... 

0.34 13.5 

0.61 15.6 

0.17 3.0 

0.20 2.6 

0.16 4.9 

0.29 12.3 

0.30 12.0 

1.09 14.7 

0.60 15.0 

0.66 14.4 

0.38 19.7 

0.48 17.7 

0.53 18.0 

0.11 14.2 

1.76 

2.44 

All races, 13 years.. ..................................................... 

White ...................................................................................... 

Black ...................................................................................... 

All races, 4-24 years.. ................................................... 

White ...................................................................................... 

Black ...................................................................................... 

All races, 25-54 years.. ................................................. 

White ...................................................................................... 

Black ...................................................................................... 

All races, 55-74 years.. ................................................. 

White ...................................................................................... 

Black ...................................................................................... 

0.85 

0.79 

2.27 

1.25 

14.5 1.28 2.5 

16.9 3.10 ‘1.9 

1.22 

2.66 

17.4 

17.0 

20.4 

2.54 

2.54 

3.65 

12.2 

l 2.4 

x0.7 

2.38 

2.34 

3.64 

19.7 2.83 *1.7 2.82 *0.7 

20.1 

“14.4 

15.0 

2.98 

3.97 

l 1.9 

l 0.1 

1.5 

2.98 

3.96 

Male 

All races, l-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.07 0.36 13.3 1.97 

White ...................................................................................... 15.0 

Black ...................................................................................... 15.7 

*1.7 

‘0.4 

0.1 

0.40 

0.12 

0.05 

13.1 

15.3 

1.92 

3.41 

All races, 13 years.. ..................................................... 3.1 3.1 

White ...................................................................................... 2.5 

Black ...................................................................................... 5.0 

2.01 

3.43 

1.20 

1 .I 1 

3.13 

1.53 

0.3 0.30 

2.5 

4.7 

1.20 

1.11 

3.12 

Al I races, 4-24 years.. ................................................... 13.3 ‘1.6 0.42 11.6 1.48 

White ...................................................................................... 13.3 1.49 ‘1.8 0.49 11.5 1.48 

Black ...................................................................................... l 14.2 4.15 l 0.7 0.22 *13.6 4.04 

All races, 25-54 years ................................................... 17.0 3.20 *I.8 0.60 15.0 3.12 

White ...................................................................................... 

Black ...................................................................................... 

16.3 3.21 

22.1 5.03 

All races, 55-74 years.. ................................................. 19.3 3.65 

0.66 

0.13 

0.68 

0.74 

0.07 

14.2 3.08 l 0.5 0.36 

21.9 5.10 l 0.4 0.44 

17.4 3.20 l 0.8 0.58 

White ...................................................................................... 

Black ...................................................................................... 

20.1 3.80 

“11.6 3.69 

*1.9 

‘0.2 

‘1.3 

l 1.4 

l 0.1 

18.0 3.33 

*Il.6 3.70 

0.11 

0.12 

0.21 

0.12 

l 0.4 

l 0.4 

*0.3 

l 0.2 

‘0.7 

‘0.5 

0.12 

0.39 

0.18 

0.20 

0.19 

0.33 

l 0.6 

l 0.2 

l 0.7 

“0.1 

+0.4 

0.36 

0.11 

0.16 

0.19 

0.14 

l 0.4 

l 0.2 

l 0.2 

l 0.2 

l 0.1 

*0.5 

0.13 

0.15 

0.09 

0.32 

10.9 0.64 

‘Totals include races other than white and Black. 

37 
Table 3. Prevalence rates and standard errors of phoria at age l-74 years, by age, sex, and race: United States, 1971.1972-Con. 

Phoria 

Age, sex, and race1 

Female 

~~ 

Rate per 100 persons and standard error 

All races, 1-74 years ................................................ 

White ...................................................................................... 

Black ...................................................................................... 

All races, 1-3 years ....................................................... 

White ...................................................................................... 

Black ...................................................................................... 

All races, 4-24 years.. ................................................... 

White ...................................................................................... 

Black ...................................................................................... 

All races, 25-54 years.. ................................................. 

White ...................................................................................... 

Black ...................................................................................... 

All races, 55-74 years.. ................................................. 

White ...................................................................................... 

Black ...................................................................................... 

16.9 1.80 

‘16.7 1 -84 

‘18.1 2.63 

3.4 1.16 

3.1 1 .I0 

5.2 3.48 

16.4 1.51 

15.8 1.40 

19.4 4.37 

17.8 2.24 

- 

17.6 2.33 

19.1 3.87 

120.0 3.14 

20.2 3.28 

*16.5 4.36 

2.6 1 0.50 1 14.1 1.62 

2.8 0.50 13.8 

*I .9 1 .I4 15.9 

0.4 0.33 3.0 

0.5 0.40 2.6 0.90 

5.2 3.48 

3.2 0.47 13.0 1.37 

1.69 

2.30 

1 .Ol 

1.43 

3.66 

1.96 

2.04 

3.77 

3.02 

3.18 

4.33 

x0.5 0.17 

‘0.4 0.17 

*0.6 0.35 

*0.3 0.16 

10.2 0.13 

*1.2 0.74 

“0.6 0.34 

x0.7 0.38 

“0.5 0.37 

“0.6 0.41 

“0.2 0.18 

‘Totals include races other than white and Black. 

38 
Table 4. Prevalence rates and standard errors of nystagmus at age 1-74 years, by age, sex, and race: United States, 1971-1972 

Age, sex, and race1 

Nystagmus 

Total II . ndular I Jerk- JerkII re 

Jerkhorizontal vertical I rotary 

Rate 12.//Ftate j x-1 Rate 

Both sexes Rate Per 100 persons and standard error 

All races, 1-74 years.. ..................... 0.5 I 0.09 

White ............................................................. 

Black.. ............................................................ 

All races, I-3 years .............................. 

White ............................................................. 

Black .............................................................. 

Al I races, 4-24 years ............................ 

White ............................................................. 

Black.. ............................................................ 

All races, 25-54 years .......................... 

White ............................................................. 

Black.. ............................................................ 

All races, 55-74 years .......................... 

White ............................................................. 

Black.. ............................................................ 

Male 

0.5 0.10 

‘0.6 0.18 

0.3 0.34 

0.4 0.41 

*0.4 0.14 

*0.4 0.16 

fO.4 0.36 

‘0.5 0.16 

“0.5 0.18 

“0.5 0.43 

*0.9 0.30 

‘0.8 0.41 

‘1.6 1.31 

All races, 1-74 years.. ..................... l 0.4 0.15 

White ............................................................. 

Black.. ............................................................ 

All races, l-3 years .............................. 

White ............................................................. 

Black.. ............................................................ 

All races, 4-24 years ............................ 

White ............................................................. 

Black.. ............................................................ 

All races, 25-54 years .......................... 

White ............................................................. 

Black.. ............................................................ 

All races, 55-74 years .......................... 

White ............................................................. 

Black.. ............................................................ 

‘0.4 0.28 

*o .9 0.99 -l- ‘0.6 0.30 

+o .3 0.17 

‘3.6 2.85 

*o.o 0.03 0.2 0.06 “0.1 I 0.04 x0.2 0.05 

*o.o 0.03 

l 0.1 0.14 

l o.o 0.05 

*0.1 0.06 

“0.1 0.05 

*o.o 0.03 

“0.4 0.43 

0.0 0.04 

0.0 0.02 

0.3 0.30 

*0.1 0.10 

l 0.1 0.05 

l 0.9 0.99 

0.07 

0.07 

0.09 

0.09 

0.35 

0.13 

0.15 

0.07 

0.18 

0.28 

1.25 

0.12 

0.14 

0.11 

0.14 

0.12 

0.74 

0.25 

0.28 

0.26 

0.11 

2.74 

0.06 

0.05 

0.34 

0.2 

0.3 

*0.2 

l 0.1 

0.3 

‘0.1 

‘0.0 

0.05 

0.00 

0.4 

*0.2 

0.41 

*0.2 0.11 

*0.1 

l 0.4 

‘0.3 

l 0.2 

*0.1 

l 0.1 

0.12 

0.07 

0.04 

l 0.3 

*0.1 

“0.5 

“0.1 

l 0.1 

*0.2 

0.05 

0.06 

0.11 0.13 

0.13 

0.04 

“0.5 

l 1.2 

10.3 

l 0.2 

l 0.3 

*0.1 

0.13 

0.29 

l o.o 0.00 0.07 I 

l 0.2 

0.7 

0.08 

0.09 

0.08 

0.10 

0.15 

0.18 

0.10 

l 0.2 

*0.1 

*0.7 

l 0.3 

‘0.4 

‘0.4 0.09 

l 0.2 

+2.9 

*0.1 0.08 

l 0.1 0.08 *0.7 0.68 

‘Totals include races other than white and Black. 

39 
Table 4. Prevalence rates and standard errors of nystagmus at age l-74 years, by age, sex, and race: United States, 1971.197’2-Con. 

Nystagmus 

Age, sex, and race1 

~1~~ 

Female Rate per 100 persons and standard error 

All races, 1-74 years.. ..................... 

White ............................................................. 

Black.. ............................................................ 

All races, I-3 years .............................. 

White ............................................................. 0.7 

Black.. ............................................................ - 

All races, 4-24 years ............................ x0.4 

White ............................................................. *0.4 

Black.. ............................................................ x0.1 

All races, 25-54 years .......................... “0.5 

-- 

White ............................................................. *0.5 

Black.. ............................................................ +0.2 / 

All races, 55-74 years .......................... *1.2 

White ............................................................. ‘1.3 

Black.. ............................................................ - 

‘Totals include races other than white and Black. 

0.10 *0.1 

0.12 *0.1 

- ‘0.0 

- *0.2 

- “0.2 

- *0.1 

- *0.6 

- ‘0.7 0.48 +0.2 0.23 *0.3 0.24 

0.15 

0.13 

0.44 

*O.l 1 0.08 *0.2 0.07 

10.2 0.08 

‘0.1 0.04 

0.6 0.62 

*0.1 

*0.1 

10.3 

0.73 

0.10 

0.12 

0.05 

0.08 

0.09 

0.10 

0.21 

40 
Table 5. Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the spherical power of the lens for each eye 

and by age, with selected standard errors: United States, 1971-1972 

lRight Left 

eve eve 

Spherical 

power of lens 

(in diopters) 4.74 4-5 

Age in years Right Left 

6-l 1 12.17 18.24 2534 3544 45.54 55-64 65-74 eve eve 

Percent distribution of lenses measured Standard 

error 

Total . . . . . . . . . 

1 .o 

2.1 

2.9 

10.0 

8.1 

8.8 

7.8 

9.4 

5.4 

11.1 

7.9 

2.8 

7.8 

1.2 

2.8 

Minus 

5.1 0 or more.. .......... 

4.1-5.0 D.. ................. 

3.140 D.. ................. 

2.1-3.0 D.. ................. 

1.6-2.0 D.. ................. 

1.1-1.5 D.. ................. 

0.6-1.0 D.. ................. 

0.1-0.5 D.. ................. 

0.0 D ......................... 

Plus 

- 

O.f-0.5 D.. ................. 

0.6-1.0 D.. ................. 

1.1-2.0 D.. ................. 

2.1-3.0 D.. ................. 

3.14.0 D.. ................. 

4.1-5.0 D.. ................. 

5.1 D or more.. .......... 

3.8 

4.1 

5.8 

10.4 

5.6 

9.8 

14.4 

12.6 

5.2 

2. 

6.8 

4.8 

2.2 

0.6 

0.3 

3.2 

2.8 

5.8 

7.5 

5.1 

7.7 

8.0 

7.7 

8.4 

10.1 

14.4 

7.0 

3.3 

1.1 

2.2 

3.4 

2.7 

6.0 

7.5 

5.0 

7.6 

8.2 

7.2 

5.8 

8.4 

10.6 

14.0 

7.4 

3.0 

1.2 

2.0 

l 14.6 

l . 

l . 

l . 

‘1.0 

*1.0 

11.0 

l 20.8 

“2.8 

*16.0 

l 11.5 

“22.4 

‘7.0 

*. 

l . 

‘1.9 

6.4 

6.2 

14.6 

16.0 

11.2 

15.8 

10.5 

6.4 

2.7 

3.0 

0.8 

2.2 

0.6 

2.6 

8.3 

7.2 

14.8 

17.1 

6.9 

10.6 

12.6 

6.8 

2.6 

3.6 

2.4 

1.8 

1.6 

0.9 

1.6 

1.2 

6.0 

3.0 

10.8 

11.0 

7.8 

13.8 

16.0 

9.6 

5.2 

5.0 

2.6 

1.6 

1.1 

1.8 

1.2 

2.7 

1.8 

3.4 

3.2 

5.0 

7.0 

7.0 

7.4 

14.0 

14.7 

13.5 

5.9 

2.6 

0.8 

1.8 

0.6 

0.6 

2.0 

3.8 

1.8 

2.2 

3.0 

5.6 

10.2 

17.3 

28.1 

11.6 

3.4 

0.8 

2.4 

1.2 

1 .o 

1.6 

2.0 

1.4 

2.1 

2.6 

3.0 

5.2 

8.6 

14.6 

25.9 

17.9 

5.6 

2.4 

4.9 

3.5 

2.6 

6.1 

7.5 

4.9 

7.4 

8.5 

6.7 

6.0 

8.5 

11.1 

13.5 

7.7 

2.8 

1.3 

1.9 

0.57 

0.40 

0.71 

0.73 

0.46 

0.82 

0.68 

0.76 

0.63 

0.81 

0.99 

0.77 

0.61 

0.32 

0.27 

0.51 

0.33 

0.69 

0.52 

0.64 

0.72 

0.78 

0.65 

0.62 

1.03 

0.99 

0.52 

0.56 

0.31 

0.33 

Table 6. Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the cylindrical power of the lens for each 

eye and by age, with selected standard errors: United States, 1971.1972 

Cylindrical 

power of lens 

(in diopters) 4-74 4-5 6-11 12-17 

Age in years Right Left 

18-24 2534 3544 45.54 5564 65.74 eve eve 

Right Left 

eye eve 

Percent distribution of lenses measured Standard 

error 

Total ......... 

Minus 

5.1 D or more.. .......... 

4.1-5.0 D.. ................. 

3.1-4.0 D ................... 

2.1-3.0 D.. ................. 

1.6-2.0 D.. ................. 

1.1-1.5 D.. ................. 

0.6-1.0 D.. ................. 

0.1-0.5 D.. ................. 

0.0 D ......................... 

Plus 

- 

0.1-0.5 D.. ................. 

0.6-l .O D.. ................. 

1.1-2.0 D.. ................. 

2.1-3.0 D.. ................. 

3.1-4.0 D.. ................. 

4.1-5.0 D.. ................. 

5.1 Dormore.. .......... 

0.2 

0.2 

0.3 

1.4 

1 .o 

2.8 

7.3 

13.4 

16.4 

10.9 

6.0 

1.6 

0.6 

0.3 

0.2 

*1.0 

l . 

1. 

1. 

l . 

l . 

“7.8 

l . 

“29.8 

l 20.5 

*7.8 

‘15.0 

l l7.1 

l . 

+. 

l 1.0 

0.1 

0.1 

0.4 

2.7 

1.6 

1.2 

8.4 

14.2 

34.6 

15.6 

12.5 

5.2 

2.7 

0.5 

0.1 

0.1 

1.4 

1.0 

3.8 

7.6 

11.4 

15.8 

11 .o 

4.8 

1.2 

0.4 

0.7 

0.2 

0.4 

0.2 

0.2 

1.6 

0.6 

1.9 

7.2 

13.6 

36.3 

17.6 

11.0 

7.6 

1 .o 

0.3 

0.2 

0.2 

0.0 

0.8 

1.4 

3.9 

9.6 

12.6 

17.4 

12.8 

8.4 

1.2 

1.3 

0.2 

0.0 

0.2 

0.3 

0.3 

1.7 

0.9 

2.8 

7.7 

13.9 

36.9 

15.9 

11.2 

5.8 

1.5 

0.6 

0.3 

0.0 

0.1 

0.2 

0.3 

1.1 

1.2 

2.7 

6.9 

13.0 

37.8 

17.0 

10.6 

6.1 

1.8 

0.5 

0.3 

0.4 

0.14 

0.17 

0.14 

0.39 

0.22 

0.41 

1.26 

1.92 

1.56 

2.13 

1.54 

0.68 

0.35 

0.22 

0.19 

0.02 

0.07 

0.11 

0.15 

0.29 

0.22 

0.44 

0.99 

1.56 

1.96 

2.48 

1.34 

0.73 

0.30 

0.13 

0.12 

0.24 

41 

1 .o 

0.2 

0.9 

1.8 

4.0 

12.6 

10.0 

12.1 

8.2 

1.0 

0.2 

2.3 

0.3 

0.8 

0.4 

3.6 

6.6 

16.7 

43.2 

13.8 

9.2 

4.0 

1.2 

15.2 

10.1 

3.8 

3.0 

0.4 

0.2 

0.0 

0.4 

0.4 

1.3 

1.2 

2.5 

6.8 

16.2 

20.5 

8.0 

4.6 

2.4 

0.9 

0.0 

0.4 
Table 7. Percent of lenses in the glasses or contact lenses of the population age 4-74 years, by the spherical and cylindrical power of the lens: United 

States, 1971-1972 

II Cylindrical power (in diopters) 

Spherical 

power of lens 

(in diopters) 

All Minus Plus 

lenses 5.1 D 4.1. 3.1- 2.1- 1.6. 1.1. 0.6. 

or 

0.1. 0.0 D 0.1. 0.6. 1.1. 2.1 D 

All lenses..... 100.0 0.1 0.3 0.3 1.4 1.0 2.8 7.3 13.4 37.4 

Minus 

5.1 D or more . . . . . . . . . . . . . 3.3 

4.1-5.0 D . . . . . . . . . . . . . . . . . . . . . 2.7 

3.14.0 D . . . . . . . . . . . . . . . . . . . . . 5.9 

2.1-3.0 D . . . . . . . . . . . . . . . . . . . . . 7.5 

1.6-2.0 D . . . . . . . . . . . . . . . . . . . . . 5.0 

1.1-1.5 D . . . . . . . . . . . . . . . . . . . . . 7.5 

0.6-1.0 D . . . . . . . . . . . . . . . . . . . . . 8.2 

0.1-0.5 D . . . . . . . . . . . . . . . . . . . . . 7.2 

0.0 D . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Plus 

- 

5.8 

0.1-0.5 D . . . . . . . . . . . . . . . . . . . . 8.4 

0.6-I .O D . . . . . . . . . . . . . . . . . . . . . 10.6 

1.1-2.0 D . . . . . . . . . . . . . . . . . . . . . 14.2 

2.1 D or more . . . . . . . . . . . . . 13.7 

more 

5.0 D 4.0 D 3.0 D 2.0 D 1.5 D 1.0 D 0.5 D 0.5 D 1.0 D 2.0 D Or more 

Percent of lenses measured 

16.5 10.9 5.9 2.7 

0.0 

0.0 

0.1 

0.0 

0.0 

0.0 

0.1 

0.0 

0.2 

0.1 

0.0 

0.0 

0.0 

0.0 

0.1 

0.0 

0.1 

0.1 

0.0 

0.1 

0.1 

0.1 

0.1 

0.0 

0.1 

0.1 

0.1 

0.1 

0.2 

0.3 

0.0 

0.0 

0.1 

0.1 

0.0 

0.1 

0.1 

0.1 

0.1 

0.1 

0.1 

0.2 

0.1 0.3 0.2 0.7 0.5 0.6 0.4 

0.1 0.2 0.2 0.8 0.4 0.5 0.:2 

0.1 0.3 0.8 2.2 0.8 0.8 0.6 

0.1 0.5 0.9 2.7 1.1 1.1 O.!j 

0.2 0.1 0.6 1.8 0.9 0.5 0.4 

0.2 0.3 0.8 3.3 1.3 0.8 0.5 

0.1 0.5 1.1 3.7 1.3 0.7 0.5 

0.2 0.4 1.3 2.2 1.6 0.7 0.3, 

0.2 0.5 0.8 2.4 0.7 0.4 

0.2 0.4 1.1 3.3 1.3 

0.2 0.8 1.4 4.1 2.5 

0.3 1.1 2.6 5.6 2.4 

0.8 1.9 1.6 4.6 1.7 

0.5 

1.1 

1 .o 

1.3 

1.3 

0.6 

0.3 

0.4 

0.6 

0.3 

0.3 

0.2 

0.4 

0.3 

0.2 

0.1 

0.3 

0.1 

0.1 

0.1 

0.1 

0.2 

Table 8. Percent of lenses in the glasses or contact lenses of the population age 4.24 years, by the spherical and cylindrical power of the’lens: United 

Statfzs, 1971.1972 

Spherical 

power of lens 

(in diopters) 

Cylindrical power (in diopters) 

All Minus Plus 

lenses 5.1 D 

or 4.1. 3.1. 2.1. 1.6. 1.1. 0.6. 0.1. 

0.0 D 

“I- 0.6. 1.1. 2.1 D 

Or more 5.0 D 4.0 D 3.0 D 2.0 D 1.5 D 1.0 D 0.5 D 0.5D l.OD 2.0D more 

Percent of lenses measured 

All lenses ..... 13.9 

Minus 

5.1 D or more.. ........... 

4.1-5.0 D.. ................... 

3.1-4.0 D.. ................... 

2.1-3.0 D.. ................... 

1.6-2.0 D.. ................... 

1.1-1.5 D.. ................... 

0.6-l .O D.. ................... 

0.1-0.5 D.. ................... 

0.0 D.. ......................... 

Plus 

- 

0.1-0.5 D.. ................... 

0.6-1.0 D.. ................... 

1.1-2.0 D.. ................... 

2.1 Dormore.. ........... 

100.0 0.0 0.5 0.7 0.8 0.8 2.7 5.3 43.9 13.8 10.0 4.7 2.9 

- 

6.3 

5.8 

12.5 

15.3 

8.7 

12.3 

10.8 

7.2 

4.1 

3.9 

3.5 

3.0 

6.6 

0.4 

0.0 

0.2 

0.1 

0.1 

0.1 

0.3 

0.1 

0.0 

0.0 

0.0 

0.2 

0.0 

0.1 

0.0 

0.2 

0.2 

0.3 

0.1 0.6 0.2 1.7 1.1 1.0 

0.3 0.5 0.4 2.0 0.7 1.3 

0.2 0.5 1.8 5.7 1.6 1.9 

0.1 0.5 2.9 6.0 2.5 1.6 

0.6 0.4 1.0 4.4 1.7 0.3 

0.4 0.8 1 .o 6.1 2.0 1.2 

0.2 0.1 1 .o 6.7 1.6 0.4 

0.0 0.2 1.3 3.4 1.1 0.4 

0.0 0.4 

0.2 

0.1 

0.3 

0.7 

1.3 1.5 0.3 0.4 

0.2 

0.6 

1.0 1.8 0.2 0.4 

0.7 1.5 0.4 0.4 

0.6 1.3 0.0 0.1 

0.7 1.8 0.6 0.6 

0.5 

0.4 

0.3 

1.1 

0.3 

0.51 

0.4’ 

0.5 

0.1 

0.3 

0.6 

0.6 

0.1 

0.2 

0.5 

0.0 

0.5 

0.2 

0.3 

0.2 

0.1 

0.1 

0.0 

0.1 

0.0 

0.1 

0.4 

42 
Table 9. Percent of lenses in the glasses or contact lenses of the population age 25-54 years, by the spherical and cylindrical power of the lens: United 

States, 1971-1972 

II Cylindrical power (in diopters) 

Spherical 

power of lens 

fin diopten) 

All Minus Plus 

lenses 5.1 D 4.1- 3.1- 2.1- 1.6- l.l- 0.6- 0.1. O”- 0.6- l.l- 2.1 D 

or IllOre 5.0 D 4.0 D 3.0 D 2.0 D 1.5 D 1.0 D 0.5 D 0.0 D 0.5 D l.OD 2.0D Or more 

Percent of lenses measured 

1.2 

0.1 

0.0 

0.2 

0.2 

0.0 

0.2 

0.1 

0.1 

0.2 

0.1 

2.8 7.6 13.2 37.4 17.0 10.8 4.9 3.1 

0.1 0.3 0.4 0.8 0.5 0.6 

0.1 0.1 0.2 0.7 0.6 0.5 

0.2 0.4 0.9 1.8 1 .o 0.5 

0.1 0.7 0.6 2.1 1.1 1.1 

0.1 0.1 0.8 2.0 1.2 0.7 

0.2 0.3 1.2 3.9 1.8 1.1 

0.1 1.1 1.6 4.9 2.0 1 .o 

0.2 0.6 2.0 2.5 2.2 1.1 

0.3 

0.3 

0.3 

0.6 

0.3 

0.3 

0.0 

0.4 

0.4 0.7 0.8 2.8 0.7 

0.1 0.5 1.1 4.5 1.6 

0.3 1.1 0.8 4.8 1.6 

0.3 0.6 2.2 3.6 1.3 

0.6 1.1 0.6 3.0 1.4 

0.5 

1.3 

0.7 

0.5 

1.2 

0.7 

0.3 

0.7 

0.5 

0.4 

0.5 

0.4 

0.2 

0.5 

0.3 

0.0 

0.1 

0.3 

0.1 

0.1 

0.1 

0.0 

0.3 

All lenses..... 100.0 0.0 0.1 0.2 1.7 

Minus 

5.1 D or more ............. 

4.1-5.0 D.. ................... 

3.1-4.0 D.. ................... 

2.1-3.0 D ..................... 

1.6-2.0 D.. ................... 

1.1-1.5 D.. ................... 

0.6-1.0 D ..................... 

0.1-0.5 D.. ................... 

0.0 D.. ......................... 

Plus 

- 

0.1-0.5 D ..................... 

0.6-t .O D.. ................... 

1.1-2.0 D.. ................... 

2.1 D or more.. ........... 

3.9 

2.8 

6.0 

7.2 

2 

11.4 

9.4 

6.6 

9.9 

9.6 

0.0 

0.0 

0.1 

0.1 

0.2 

0.2 

0.1 

0.1 

0.0 

0.1 

0.0 

0.2 

0.2 

0.3 

0.2 

0.0 

0.0 

0.0 

0.1 

0.1 

Table 10. Percent of lenses in the glasses or contact lenses of the population age 55-74 years, by the spherical and cylindrical power of the lens: 

United States, 1971-1972 

I Cylindrical power (in diopters) 

Spherical 

power of lens 

(in diopters) 

Minus Plus All 

lenses 5.1 D 

or 

4.1- 3.1- 2.1- 1.6- 1.1- 0.6. O-l- O.l- 0.6- l.l- 2.1 D 

more 

5.0 D 4.0 D 3.0 D 2.0 D 1.5 D 1.0 D 0.5 D 0.0 D 0.5 D l.OD 2.0 D Or more 

Percent of lenses measured 

All lenses ..... 100.0 0.3 0.2 0.1 1.3 0.9 2.8 8.2 13.2 33.5 17.5 11.8 8.0 

Minus 

5.1 D or more.. ........... 0.8 

4-l-5.0 D.. ................... 0.7 

3-l-4.0 D.. ................... 1.7 

2.1-3.0 D.. ................... 3.2 

1.6-2.0 D.. ................... 1.5 

1.1-1.5 D.. ................... 2.2 

0.6-1.0 D.. ................... 2.8 

0.1-0.5 D.. ................... 4.4 

0.0 D.. ......................... 5.8 

Plus 

- 

0.1-0.5 D.. ................... 

0.6-1.0 D.. ................... 

1.1-2-O D.. ................... 

2.1 D or more.. ........... 

9.5 

16.1 

27.4 

23.9 

2.2 

0.0 

0.0 

0.1 

0.2 

0.1 

0.2 

it: 

0.1 

0.6 

0.0 0.0 

0.1 

0.0 

0.1 

0.3 

0.2 

0.4 

0.2 

0.4 

1.1 

0.0 0.1 0.3 0.0 0.3 0.0 

0.1 0.1 0.0 0.0 0.1 0.1 

0.1 0.2 0.2 0.2 0.5 0.5 

0.4 0.1 1.2 0.3 0.8 0.1 

0.1 0.0 0.2 0.1 0.2 0.3 

0.1 0.2 0.5 0.4 0.2 0.6 

0.1 0.6 0.4 0.4 0.5 0.5 

0.4 0.6 1.0 1 .o 0.4 0.4 

0.3 0.4 2.6 0.9 0.5 0.5 

it”7 

2.3 

3.3 

1.0 3.0 1.6 

2.4 5.0 4.9 

4.2 10.7 5.0 

3.3 8.4 2.7 

1.6 

i:: 

1.9 

1.4 

0.9 

1.1 

1.6 

0.1 

0.3 

0.0 

0.2 

0.5 

0.0 

0.1 

0.2 

0.0 

0.1 

0.2 

0.2 

0.3 

43 

0.0 

0.2 

0.0 

0.0 

0.1 

0.2 

0.0 

0.1 

0.1 

0.4 

0.2 

0.1 
Table 11. Percent of lenses in the glasses or wntact lenses of the population age 4-74 years, bv sex and the power of the sphere or cylinder and by age and sexfornegativeand 

positive corrections: United States, 1971-72 - 

F 

- 

f 

Sphere I Cylinder Sphere I Cylinder 

I 

Left eye Right eye Left we 

I 

Left eve Right eve Left eye lE 

n 

Poweroflens' 

(in diopten) andage Right eye Right eye 

M&S 1 ” Felales M&S Fe- M&S Females males Males , 

Females uales 

I 

Females 

POWER 

Percentoflenses measured Standard error 

Minus 

5.1 D or mDre .............................. 

4.1-5.0 D ..................................... 

3.14.0 D ..................................... 

2.1-3.0 D ..................................... 

1.6-2.0 D ..................................... 

1.1-1.5 D ..................................... 

0.6-1.0 0 ..................................... 

0.1.0.5 D ..................................... 

0.0 D ........................................... 

PIUS 

- 

3.5 3.6 2.9 3.3 

2.6 2.7 2.9 2.7 

7.2 5.3 6.6 5.2 

7.6 7.5 8.0 7.1 

4.4 5.3 4.6 5.4 

8.7 6.5 9.2 6.6 

9.5 7.8 9.0 7.3 

6.4 6.8 7.3 8.0 

6.0 6.0 6.4 5.1 

0.6 

0.6 

1.4 

0.6 

2.9 

6.8 

15.3 

37.2 

0.3 0.2 0.0 0.87 0.65 0.87 0.57 

0.1 0.2 0.1 0.43 0.58 0.62 0.54 

0.2 0.6 0.0 0.96 0.80 1.13 0.63 

1.8 0.7 1.3 1.17 0.89 0.90 0.73 

1.0 1.0 1.3 0.66 0.75 0.80 0.90 

2.8 2.6 2.7 1.30 0.95 1.19 0.74 

8.3 7.4 6.6 1.02 0.77 0.99 0.96 

13.0 12.8 13.1 1.40 0.84 1.10 0.92 

36.7 37.7 38.1 0.81 0.79 0.88 0.80 

0.36 

0.31 

0.57 

0.17 

0.65 

1.49 

2.15 

2.30 

0.23 0.17 0.03 

0.13 0.24 0.09 

0.11 0.36 0.04 

0.81 0.33 0.53 

0.34 0.29 0.30 

0.49 0.70 0.44 

1.43 1.15 1.19 

1.98 1.75 1.72 

1.82 2.61 2.03 

0.14.5 D ..................................... 

0.6.1 .O D ..................................... 

1.1-2.0 0 ..................................... 

2.1-3.0 D ..................................... 

3.1-4.0 D ..................................... 

4.1-5.0 D ..................................... 

5.1 D or more .............................. 

CORRECTION 

a.7 8.3 7.7 8.9 14.5 16.9 17.4 16.6 0.61 0.92 1.34 0.89 2.22 2.33 3.24 2.39 

11.9 10.5 9.8 10.4 12.9 10.0 10.9 10.5 1.27 0.88 1.35 1.09 2.43 1.22 1.80 1.45 

13.2 13.9 14.6 14.6 4.8 6.4 5.5 6.5 1.35 1.10 1.54 0.97 0.97 1 .oo 1.03 1.08 

5.5 9.2 5.0 8.4 1.4 1.5 1.9 1.8 0.65 1.03 0.90 0.82 0.36 0.43 0.40 0.33 

2.2 3.2 2.7 3.7 0.4 0.7 0.3 0.6 0.74 0.82 0.72 0.71 0.25 0.32 0.18 0.22 

1.3 1.3 1.2 1.0 0.5 0.2 0.4 0.1 0.48 0.37 0.47 0.33 0.26 0.16 0.26 0.10 

1.5 2.1 2.0 2.4 0.0 0.0 0.3 0.5 0.50 0.37 0.58 0.42 0.02 0.03 0.31 0.31 

4-5 veers 

Minus ........................................... 

PIUS .............................................. 

6-11 years 

'45.2 '11.0 '56.8 '5.6 l _ l 49.4 l . l . 28.33 14.95 !3.56 30.04 

%4.8 '83.5 '40.6 '88.9 '58.8 l 45.1 '56.8 l 94.5 28.33 12.01 !1.18 27.18 23.56 

12.87 

17.01 23.56 4.74 

Minus ........................................... 

PIUS .............................................. 

12.24years 

51.3 48.5 50.2 51.1 '14.3 '24.1 '16.5 '23.5 11.40 7.29 Il.28 7.80 6.67 7.64 7.31 7.30 

"39.0 35.0 43.2 43.0 '22.9 '37.2 -28-7 '41.1 9.95 7.73 10.19 7.84 8.19 11.51 9.78 11.44 

Minus ........................................... 

PIUS .............................................. 

2544 years 

86.4 85.3 88.1 84.4 302 22.0 30.6 23.1 3.27 2.69 3.03 3.49 6.12 2.97 4.80 3.40 

l 11.9 13.3 910.4 13.6 27.6 33.5 31.1 30.3 3.29 2.71 3.18 2.87 4.39 5.51 5.71 4.61 

Minus ........................................... 71.6 71.5 72.1 72.7 33.9 30.2 24.0 27.1 4.65 2.75 5.20 2.28 6.88 4.09 3.35 4.29 

PIUS .............................................. 25.8 23.7 23.4 23.2 31.0 39.1 35.8 39.8 5.11 2.69 5.53 1.97 7.13 4.52 7.22 5.38 

46.64 years 

Minus ........................................... 32.2 25.7 33.1 24.9 25.8 28.3 24.0 23.8 3.64 2.52 3.62 2.41 3.66 3.86 3.49 3.39 

PIUS .............................................. 58.9 67.0 58.2 68.0 38.0 32.2 39.6 35.7 3.75 2.45 3.87 2.60 4.28 3.76 4.55 3.60 

65.74ysers 

Minus ........................................... 14.4 14.5 15.9 14.9 28.7 28.3 29.6 29.0 2.80 2.38 2.54 1.77 4.58 4.43 

PIUS .............................................. 79.0 80.9 78.1 81.2 41.3 42.9 39.0 41.1 3.46 2.63 3.37 1.82 5.36 5.19 

4.69 

6.02 

- 

4.79 

5.13 

lAlgcbraic sum of spherical and cylindrical power oflens. 

44 
Table 12. Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the axis deviation of the lens for each eye and 

by age, with selected standard errors: United States, 1971-1972 

I I -L Right Left 

eye eye 

Standard 

error 

4-74 4-5 6-11 12-17 

Age in years Right Left 

18-24 2534 3544 45-54 5564 65-74 eye eye 

Axis deviation 

in lens 

(in degrees) 

Percent distribution of lenses measured 

Total tested . . . . 100.0 11 100.0 100.0 100.0 ) 100.0 1 100.0 100.0 

None?. ............................ 37.4 29.7 45.7 43.0 44.2 34.3 34.2 

lo-45O.. ........................... 9.6 7.0 4.8 6.0 7.6 8.0 13.4 

46’-go’........ ................... 21.9 42.7 23.0 20.9 20.0 28.6 19.6 

91°-135O.. ........... . ........... 12.0 18.6 9.1 13.3 1 I .4 12.4 12.2 

1360-1800.. ..................... 19.1 2.0 17.4 16.8 16.8 16.7 20.6 

100.0 

36.5 30.2 

8.8 12.1 

21.9 23.0 

13.4 12.2 

19.4 22.5 

100.0 100.0 . . . 

36.8 37.8 1.50 

11.0 8.3 0.75 

19.4 24.4 0.91 

13.9 10.2 1.06 I 18.9 19.3 1.13 

. . . 

T 

1.98 

0.82 

1.36 

1.18 

1.24 

‘The category “None” includes population with piano cylinder. 

Table 13. Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the spherical equivalence of the lens for each 

eye and by age, with selected standard errors: United States, 1971-1972 

- 

i 

-L- Right Left 

eye we 

Standard 

error 

4-74 4-5 

Age in years 

6-11 12-17 18-24 25-34 35-44 45-54 5564 65-74 

Percent distribution of lenses measured 

Right Left 

we we 

Spherical equivalency1 

of lens (in dioptersi 

Total tested . . . . 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 . . . . . . 

Minus 

10.1 D or more.. ............. 

7.6-I 0.0 D ...................... 

5.1-7.5 D ........................ 

4.1-5.0 D ........................ 

3.1-4.0 De....................... 

2.1-3.0 D ........................ 

1.6-2.0 D ........................ 

1.1-1.5 D.. ...................... 

0.6-1.0 D ........................ 

0.1-0.5 D.. ...................... 

0.2 

0.4 

2.7 

2.7 

5.8 

7.4 

4.7 

ii 

7.6 

l m 0.2 0.8 0.8 0.4 

l 0.8 0.2 1.1 2.1 0.8 

“14.8 0.6 5.1 5.0 5.0 

l - 1.3 5.2 8.0 4.0 

l - 2.9 15.0 14.7 10.0 

*- 8.7 18.2 14.9 11.8 

*- 9.2 11.1 9.0 6.6 

l - 9.0 13.0 10.6 15.3 

*- 8.6 11.2 12.0 14.7 

“14.6 10.4 6.4 7.7 9.0 

0.4 

4.2 

3.8 

6.2 

7.0 

5.3 

11.5 

16.5 

11.7 

2.6 0.6 

1.8 0.4 

3.6 1.4 

3.5 4.4 

3.8 1.2 

7.2 3.6 

8.5 3.1 

9.2 5.1 

0.1 0.2 0.1 0.14 0.09 

0.1 0.5 0.4 0.19 0.16 

0.8 2.7 2.7 0.46 0.46 

0.6 2.8 2.6 0.30 0.20 

1.2 5.9 5.7 0.44 0.51 

2.6 7.3 7.5 0.66 0.52 

1.4 4.6 4.8 0.52 0.55 

1.8 8.3 7.5 0.88 0.77 

2.7 9.0 8.5 0.68 0.53 

4.4 7.7 7.5 0.57 0.58 

0.0 D .............................. 3.4 l 3.8 3.4 2.2 2.4 2.9 3.7 5.1 3.6 2.8 3.1 3.8 0.49 0.37 

Plus 

- 

0.1-0.5 D ........................ 

0.6-1.0 D ........................ 

1.1-1.5 D.. ...................... 

1.6-2.0 D ........................ 

2.1-3.0 D ........................ 

3.1-4.0 D ........................ 

4.1-5.0 D ........................ 

5.1 D or more.. ............... 

7.7 

11.0 

%I 

7.6 

3.0 

1.2 

2.2 

l 10.7 10.3 

l 16.2 10.8 

l 12.4 4.2 

l 7.8 3.6 

‘14.1 6.0 

l - 6.6 

l 1.0 1.4 

l 3.8 2.6 

2.4 

1.4 

1 .o 

1.4 

1.1 

2 

1.0 

3.2 5.0 7.9 

1.4 5.6 7.4 

2.7 1.2 3.7 

0.4 1.2 3.5 

1.8 2.2 4.2 

0.9 1.0 1.9 

1.0 0.7 0.8 

1.4 2.6 0.3 

12.8 

15.5 

10.2 

65:: 

2.0 

1.0 

1.8 

8.9 6.6 7.8 7.6 0.57 0.58 

17.5 13.6 10.8 11 .o 0.90 1.04 

16.4 15.2 8.7 8.8 1.02 0.52 

15.6 12.8 6.8 7.0 0.66 0.64 

10.8 19.3 7.6 7.7 0.68 0.49 

3.8 6.4 3.0 3.0 0.51 0.49 

1 .o 3.0 1.1 1.4 0.25 0.33 

2.6 4.6 2.1 2.4 0.31 0.41 

‘Algebraic sum of spherical and one-half of cylindrical power in lens. 

45 
Table 14. Percent distribution of lenses in the glasses or contact lenses of the population age 4-74 years, by the power of the lens for each eye and by age, 

with selected standard errors: United States, 1971-1972 

Power1 of lens 

(in diopters) 4-74 4-5 6-11 12-17 

Age in years Right Left Right Left 

18-24 25-34 3544 45-54 55-64 65-74 we eve we we 

Percent distribution of lenses measured Standard 

errOr 

Total tested . . . . 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 ..* . . . 

Minus 

10.1 D or more.. ............. 

7.6-10.0 0 ...................... 

5.1-7.5 D ........................ 

4.1.5.0 D.. ...................... 

3.1-4.0 D ........................ 

2.1-3.0 D.. ...................... 

1.6-2.0 D ........................ 

1.1-1.5 D ........................ 

0.6-1.0 D ........................ 

0.1-0.5 D ........................ 

0.2 v.0 

0.6 '0.8 

2.6 "13.9 

2.6 l - 

5.5 l . 

7.0 l . 

4.9 l . 

7.4 *- 

8.6 l - 

6.8 l 6.8 

0.4 0.0 

0.3 

0.8 

3.8 

7.7 

4.4 

11 .o 

9.6 

13.2 

0.8 0.6 0.3 0.2 

1.1 2.8 1.0 0.5 

5.2 4.7 4.8 4.4 

6.0 5.8 4.6 2.8 

13.9 14.5 8.7 6.4 

17.8 15.7 11.2 6.0 

11.3 6.8 7.6 6.0 

11.5 9.9 15.9 9.8 

12.1 13.9 13.2 14.7 

5.4 8.3 8.4 10.2 

1.6 0.7 

2.5 0.6 

3.6 1.2 

3.2 4.7 

4.9 1.4 

6.1 3.0 

8.1 3.1 

8.4 3.4 

0.1 0.3 0.1 0.14 0.09 

0.1 0.6 0.5 0.21 0.18 

0.8 2.9 2.2 0.46 0.44 

0.6 2.6 2.7 0.31 0.32 

1.0 5.3 5.7 0.62 0.66 

1.5 7.3 6.8 0.67 0.59 

2.1 4.7 5.1 0.57 0.47 

2.0 7.5 7.2 0.84 0.76 

3.0 9.0 8.1 0.75 0.74 

3.9 7.0 6.7 0.50 0.58 

0.0 D .............................. 5.4 l 9.6 4.2 3.2 3.6 3.6 7.2 8.8 5.0 4.3 5.1 5.7 0.59 0.49 

PIUS 

- 

0.1-0.5 D ........................ 

0.6-1.0 D ........................ 

1.1-1.5 D ........................ 

1.6-2.0 D ........................ 

2.1-3.0 D ........................ 

3.1-5.0 D ........................ 

5.1 D or more.. ............... 

8.0 *to.7 5.9 

10.0 l 2'l .4 13.0 

8.8 l - 5.4 

6.9 l 4.6 2.5 

7.6 "19.4 6.5 

4.6 l 7.0 8.5 

2.5 '4.8 2.8 

3.4 

0.9 

1.8 

::"2 

1.1 

1.3 

4.6 4.4 9.4 11.3 10.4 7.1 

1.3 6.2 8.0 13.2 14.6 12.8 

2.8 1.7 4.4 9.9 16.5 14.8 

0.2 0.4 2.8 7.2 14.2 13.5 

1.1 2.8 4.0 5.0 13.2 17.2 

2.4 1.6 2.6 4.4 5.2 10.2 

1 .o 3.6 0.6 1.8 2.8 5.0 

8.0 

9.9 

9.0 

ii 

414 

2.4 

7.9 0.55 0.61 

10.0 0.84 0.95 

8.8 0.98 0.78 

8.1 0.49 0.86 

7.0 0.94 0.68 

4.8 0.58 0.62 

2.6 0.31 0.39 

‘Algebraic sum of spherical and cylindrical power of lens. 

Table 15. Percent distribution of population age 4-74 years, by monocular visual acuity on the pinhole test for those with less than 20120 usual visual acuiN at 

each level of usual visual acuity: United States, 1971-1972 

II Pinhole acuity 

Usual visual acuity Total Less 

20/20 20/25 20/30 20/40 20/50 20/60 20/70 20/80 20/100 20/200 20/400 than 

201400 

Percent distribution 

7.6 3.2 

-= G 

0.6 

1.1 

27.9 

17.2 

14.0 

21 .l 

16.9 

14.5 

10.6 

10.3 

0.6 

-- 

0.1 

0.1 

0.4 

22.4 

14.0 

7.5 

19.6 

15.8 

11.2 

16.3 

3.4 

20/25 or less ............ 

20/26.. ...................................... 

20/30.. ...................................... 

20/40.. ...................................... 

20/50.. ...................................... 

20/60.. ...................................... 

20170.. ...................................... 

20/80.. ...................................... 

20/l 00 ...................................... 

20/200.. .................................... 

20/400.. .................................... 

Less than 20/400.. .................... 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

16.0 

23.1 

16.0 

9.3 

7.7 

7.5 

4.4 

0.5 

::I 

2.2 

46 
Table 16. Percent distribution of population age 4-24 years, by monocular visual acuity on the pinhole test for those with less than 20/20 usual visual acuity at 

each level of usual visual acuity: United States, 1971-1972 

Pinhole acuity 

Total Less 

20/20 20/26 20/30 20/40 20/50 20/60 20/70 20/80 20/100 20/2W 20/400 than 

20/400 

Usual visual acuity 

20/25 or less.. ........... 

20125.. ...................................... 

20/30 ........................................ 

20140.. ...................................... 

20/W ........................................ 

20/60 ........................................ 

20170 ........................................ 

20180 ........................................ 

20/l 00 ...................................... 

20/200.. .................................... 

20/400.. .................................... 

Less than 20/400 ...................... 

100.0 24.0 6.1 2.7 1.6 

100.0 

loo.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

0.4 0.0 

58.6 0.6 

23.6 28.8 

18.4 11.7 

21.0 7.0 

25.0 7.2 

1.6 5.2 

20.8 14.0 

27.7 12.8 

2.4 38.2 

0.4 0.5 

0.0 

19.8 

14.1 

24.8 

9.1 

12.8 

1.1 

0.1 

14.2 

22.4 

6.4 

1.6 

3.0 

2.6 

0.3 

48.2 

22.4 

0.4 

0.2 

77.6 

Table 17. Percent distribution of population age 2644 years, by monocular visual acuity on the pinhole test for those with less than 20120 usual visual acuity at 

each level of usual visual acuity: United States, 1971-1972 

Pinhole acuity 

Usual visual acuity Total Less 

20/20 20/26 20/30 20/40 20/50 20/60 20/70 20/80 2O/lW 20/2W 20/4W than 

201400 

Percent distribution 

20/25 or less . . . . . . . . . . . . . loo.0 4.5 I 1 .o 0.6 I 0.8 0.4 

==I 

24.0 1 48.8 1 17.5 

I I 

1.6 

0.2 

0.7 

20.8 

16.0 

23.9 

0.0 

0.4 

21.0 

1.3 

2.8 

23.9 

15.0 

32.1 4.2 

’ 62.9 

36.8 

’ 38.7 

28.9 

22.1 

7.8 

20/25.. ...................................... 

20/30.. ...................................... 

2Of40.. ...................................... 

20/w ........................................ 

20160 ........................................ 

20/70.. ...................................... 

20180.. ...................................... 

20/100.. .................................... 

20/200 ...................................... 

20/400.. .................................... 

Less than 20/4W.. .................... 

100.0 34.0 

100.0 17.2 

100.0 12.6 

100.0 11 .o 

100.0 4.8 

100.0 - 

2.9 

46.3 

27.5 

22.7 

15.3 

18.4 

67.6 

21.0 

10.8 

16.8 

- I 

14.0 

20.5 

19.7 

12.4 

loo.0 - 

100.0 - 

100.0 16.0 

100.0 - 

100.0 - 

45.7 

2.6 61.9 . 

3.5 . 

16.8 96.5 

47 
fable 18. Percent distribution of pnpulatibn aga 45-74 yeah, by monocular visual acuity on the pinhola test for those with less than 29/20 uiuol visual aauity at 

each level of usual visurl acuity: United States. 1971-1932 

Usuel visual acuity 

20/25 or less ............. 

20/25.. ...................................... 

20/30.. ...................................... 

20140 ........................................ 

20156 ........................................ 

20169 ........................................ 

$2 

........................................ 

........................................ 

29llW.. .................................... 

20/1W ......................... I.. .......... 

2901400 ...................................... 

Lass than 20/4W.. .................... 

Pinhole acuity 

fotmi ‘Lass 

20/20 20125 20130 20/40 20/50 20/60 2CV70 PO/80 20/160 20/299 201400 thrn 

26/409 

60.7 

81.5 

36.9 

40.0 

27.4 

15.1 

14.0 

lo,2 

30.0 

18.2 

0.8 

2.4 

18.7 

= 

2.8 

45.9 

22.4 

21.7 

24.4 

13.0 

12.0 

8.4 

18.2 

2.6 

0.2 

0.2 

16.4 

12.6 

19.0 

2.6 

3.0 

6.6 

3.5 

0.6 1 0.4 0.4 0.6 1.0 1.2 

0.0 

0.1 

24.9’ 

8:: 

. 

. 

4.6 

47.2 

16.1 

2 

0:6 

0.; 

48 
Table 19. Percent of population age 4-74 years with usual distance vision below 20/40 reaching the 20/20 lava1 in spherical refraction or retinoscopy,by 

the strength of the lens required for each eye and by age and sax, with standard errors for totals: United States, 1971-1972 

Eye tasted, age, and sex 

Percent of 

populetion with 

usual distance 

vision less then 

2oMo 

Righteye 

Both sexes, 4-74 years . . . . . . . . . . . . . . . . . . 

4-24 years ..................................................... 

25-54 years.. ................................................. 

55-74 years .............. . .................................... 

Males, 4-74 years.. .............................. 

Females, 4-74 years.. .......................... 

Both sexes, 4-74 years .................................. 

Males, 4-74 years .:. ....................................... 

Females, 4-74 years ...................................... 

Both sexes, 4-74 years ,...................... . . . . . . . . . . . 

Left eye 

Both sexes, 4-74 years ,................. 

4-24 years.. ................................................... 

25-54 years ................................................... 

55-74 years.. ................................................. 

Males, 4-74 years.. .............................. 

Percent reaching 20/20 with addad lens 

22.3 1 2.4 1 

37.3 

27.5 

8.8 

26.9 

18.3 

44.1 I 32.5 

l 9.7 40.8 47.8 

l m 71.1 26.2 

l - 6.0 t 4.2 

*- 55.6 38.2 

‘7.2 32.5 28.1 1 

Standard error 

4.5 

4.2 

17.2 

6.6 

6.5 

0.48 

0.63 

0.58 I 

Parcant of tests with added lens 

..- I 100.0 1 4.6 1 15.1 I 25.9 1 4.1 1 30.4 1 12.5 1 7.4 

Percent reaching 20/26 with addad lens 

6.0 20.7 5.9 29.0 26.5 ‘27.5 13.3 15.1 16.7 

4.4 27.8 l 13.9 21.9 49.6 l - 1.2 l - l - 

4.1 19.1 l 5.9 l 38.1 16.9 l m 5.2 l 40.2 l 18.9 

14.0 14.7 l m 40.9 0.6 l 35.6 19.9 5.3 l 8.2 

5.3 25.8 l 5.3 33.3 36.9 l m 16.6 202 *. 

6.6 16.9 ‘6.5 24.1 19.9 ‘45.4 Il.4 7.2 l 25.5 

Standard error 

Both sexes, 4-74 years .................................. 

Males, 4-74 years .......................................... 

Females, 4-74 years ...................................... 

0.34 

0.44 

0.45 I 

Percent of tests with added lens 

Both sexas, 4-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

I 

100.0 4.1 16.6 35.0 1.0 29.9 9.6 3.8 

49 
Table 20. Percent distribution of population age 4-74 years with usual dktance vision less than 20/40, by maximum monocular visual acuity in spherical 

refraction or retinoscopy for those at each level of usual visual acuity and by age: United States, 1971-1972 

Acuity in spherical refraction or retinoscopy (eyes tested) 

Age and usual visual acuity Total 20120 Less 

or 20125 20/30 20/40 20/50 20/60 20/70 20/80 20000 20/200 20/400 than 

better 20/400 

All ages, 4-74 years Percent distribution 

20/50 or less . . . . . . . . . . . . . 100.0 21.6 22.6 

20/60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 25.0 27.7 

20160 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 17.6 24.2 

20170 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 24.4 21.2 

20/80 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 6.7 28.8 

20/100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 18.8 15.6 

201200 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 28.4 17.9 

20/400 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 14.9 3.6 

Less than 20/400 . . . . . . . . . . . . . . . . . . . . . . 100.0 1.9 1.6 

4-24 years 

20/50 or less . . . . . . . . . . 100.0 32.6 19.6 

25-54 years 

20150 or less . . . . . . . . . . . . . 100.0 23.3 27.3 

55-74 years 

20150 or less ..,..,..,.... 100.0 11.8 21.3 

16.6 1 16.4 0.6 1.2 2.2 2.0 1 0.9 

0.2 

5.0 

0.6 

1.4 

3.0 

1 .o 

0.4 

3.2 

6.7 

1.1 

3.3 

1 .o 

0.9 

7.0 0.1 0.3 

14.0 19.4 _ 

10.2 8.4 2.4 

5.3 9.1 10.2 

7.6 4.2 14.4 

1.3 6.8 9.3 

10.0 1.1 4.8 

0.8 0.7 - 

17.9 21.6 

16.2 8.6 

17.8 15.5 

9.0 30.7 

14.0 17.0 

12.9 6.8 

16.2 17.6 

7.2 

8.4 

2.0 4.4 30.8 -I- 21.1 11.2 4.9 2.7 3.3 -I---’ 6.4 6.6 1.2 

0.8 

10.3 16.4 ---I-- 14.3 21.3 4.0 4.2 ! - 

(12/ 0.5 1.5 2.2 

Table 21. Percent of population age 4-74 years with usual distance vision less than 20140. by strength of added lens used and maximum visual acuity reached in 

spherical refraction or retinoscopy for each eye: United States, 1971-1972 

Total popu- Acuity in spherical refraction or retinoscopv 

lation with 

usual distance 20/20 Less 

vision less or 20125 20/30 20140 20150 20160 20170 20/80 2OllOO 201200 201400 than 

than 20/40 better 201400 

Added lens power 

fin diopters) 

Right eve 

Total.. ................ 22.2 24.6 12.8 15.4 

== 

8.2 5.4 

-3.1 D or less.. ................... 

-1.6 D to -3.0 D ............... 

-0.1 D to -1.5 D.. ............. 

0.0 D ................................. 

0.1 D to 1.5 D.. ................. 

1.6 D to 3.0 D ................... 

3.1 D or more.. .................. 

4.6 0.1 0.8 0.0 2.0 0.5 0.3 

15.1 6.7 2.9 2.4 0.5 1.7 0.1 

26.0 8.4 6.9 4.2 3.4 1.3 1.1 

3.8 0.2 0.1 0.7 0.5 0.9 0.0 

30.5 5.3 8.3 3.6 6.0 2.9 1.7 

12.6 1.3 3.6 1.6 1.6 0.4 0.6 

7.4 0.2 2.2 0.3 1.4 0.5 1.6 

Left eye 

Total.. ................ 100.0 20.7 20.3 18.5 17.4 7.8 5.9 

-3.1 D or less ..................... 

-1.6 D to -3.0 D ............... 

-0.1 D to -1.5 D.. ............. 

0.0 D ................................. 

0.1 0 to 1.5 D ................... 

1.6 D to 3.0 D ................... 

3.1 D or more .................... 

4.1 0.2 

16.6 4.8 

35.0 9.4 

1 .o 0.3 

29.9 4.0 

9.6 1.4 

3.6 0.6 

‘I .o 

6.0 

6.4 

5.8 

0.9 

0.2 

0.1 0.1 0.3 

2.9 1.2 0.5 

8.7 4.4 2.9 

0.2 0.2 0.1 

4.4 8.7 2.7 

2.0 2.1 1.1 

0.2 0.7 0.2 

1.9 

0.1 

1.1 

2.8 

0.0 

1.1 

0.4 

0.1 

0.2 

0.4 

0.1 

0.0 

0.1 

0.0 

1.3 1.3 2.6 0.9 

0.2 

0.1 

i:: 

0.1 

0.1 

0.0 

0.1 

0.4 

0.0 

0.6 

0.2 

0.6 

1.5 

0.5 

0.7 

0.0 

0.0 

0.0 

0.2 

1.1 3.0 1.4 0.6 

0.0 

0.2 

0.7 

0.1 

0.1 

0.2 

0.2 

0.8 

0.0 0.6 

0.6 0.1 

1.5 0.4 

0.; 

0.1 

0.2 

0.3 

4.0 

= 

0.0 

0.2 

0.2 

it: 

2.4 

0.0 

3.2 

Z 

0.4 

0.9 

1 .o 

0.6 

0.3 

0.0 

50 
Table 22. Number and percent of population age 4-74 years with usual distance vision less than 20/40 whose acuity was increased to 

20/20 in at least one eye and whose acuity was not increased to 20/20 in either eye, by strength of added lens used in spherical 

refraction or retinoscopy for maximum visual acuity in each eye: United States, 1971-1972 

Right eye: added lens strength (in diopters) 

-3.1 D -1.6 D -0.1 D 0.1 D 1.6 D 3.1 D 

Total or to 

-1:: D 

0.0 D 

I.‘,“, 3.bOD 

or Not 

less -3.0 D more tested1 

Number Percent 

in of 

thou- PoPusands lation 

Left eye: added lens 

strength (in diopters) 

Acuity increased to at 

least 20/20 in one eye 

with added lens 

Percent 

Total . . . . . . . . . . . . . . . . 6,634 I 100.0 3.7 9.9 14.7 2.4 19.4 9.4 5.8 34.7 

-3.1 D or less.. ................. 

-1.6 D to -3.0 D.. ............ 

-0.1 D to -1.5 D.. ............ 

0.0 D.. .............................. 

0.1 D to 1.5 D.. ................ 

1.6 D to 3.0 D.. ................ 

3.1 D or more.. ................ 

Not testedl.. .................... 

Less than 20/20 acuity 

in better eye with 

added lens 

Total . . . . . . . . . . . . . . . . 2,455 

-3.1 D or less.. ................. 

-1.6 D to -3.0 D.. ............ 

-0.1 D to -1.5 D.. ............ 

0.0 D.. .............................. 

0.1 D to 1.5 D.. ................ 

1.6 D to 3.0 D.. ................ 

3.1 D or more.. ................ 

3.7 

_- 

_I 

___ 

___ 

- 

1.4 

_- 

_- 

___ 

- 

___ 

2.6 

7.8 

19.1 

0.2 

13.1 

5.0 

1.6 

50.6 

0.1 

4.3 0.3 

0.6 5.2 

3.6 5.0 9.2 

100.0 2.8 15.2 31.6 

2.5 

17.7 

30.1 

1.5 

34.6 

9.0 

4.6 

2.3 

0.5 

0.2 

11.7 

1.5 

0.5 

1.3 

5.9 

24.1 

1.6 

0.2 

2.2 

4.7 

2.5 

3.2 

13.3 

0.0 

10.3 

4.4 

1.0 

. . . 

. . . 

. . . 

. . . 

. . . 

. . . 

. . . 

. . . 

2.8 

16.6 

0.6 

0.4 

8.4 

0.2 

5.6 

31.6 9.4 4.7 

0.1 

2.2 

0.1 

28.6 

0.7 

2.3 

7.0 

0.1 

4.6 

1.8 

1.4 

1.5 

‘The acuity in this eye was 20/20 or better and the trial lens test was not performed. 

Table 23. Percent of lenses used in retinoscopy by type of spherical equivalence in added lens for maximum visual acuity among 

population age 25-74 years and type in present glasses or contact lenses: United States, 1971-1972 

Type of spherical equivalence in present glasses Total 

Type of spherical 

equivalence in lens 

used on retinoscopy 

Minus Zero Plus 

Percent 

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............ 100.0 33.0 2.2 64.8 

Minus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........................... 36.3 22.3 0.7 13.3 

Zero . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................. 8.4 1.0 1.1 6.3 

Plus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .............................. 55.3 9.7 0.4 45.2 

51 
Table 24. Percent of lenses used in retinoscopy by spherical equivalence in added lens for maximum visual acuity among population age 

25-74 years and in present glasses or contact lenses: United States, 1971-1972 

Spherical equivalence in 

present glasses (in diopters) 

I Spherical equivalence on refraction (in diopters) 

Total -3.1 D -1.6 D .-O.l D 0.1 D 1.6 D 3.1 D 

or 0.0 D or 

less -3:: D -1:: D l.:D 3.tgOD more 

Percent 

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 100.0 II 7.1 1 12.8 1 13.1 1 2.2 1 30.4 1 18.5 1 15.9 

-3.1 D or less.. ..................................................................... 

-1.6 D to -3.0 D ................................................................. 

-0.1 D to -1.5 D.. ............................................................... 

0.0 D ................................................................................... 

0.1 D to 1.5 D ..................................................................... 

1.6 D to 3.0 D ..................................................................... 

3.1 D or more.. .................................................................... 

4.9 4.7 

6.1 1.9 

25.3 0.5 

8.4 - 

25.2 - 

16.4 - 

13.7 

_ 

2.1 

6.9 

0.7 

0.8 

2.3 

0.2 

0.2 

5.8 

0.3 

6.6 

0.7 

1.1 

0.4 

9.4 

’ 6.1 

11.8 

3.1 

1.2 

2.7 

6.0 

8.0 

0.6 

2.6 

13.1 

52 
AIf+, xx. rnd r&d Totrl PO/l0 2Qll5 20120 2oi25 2ol30 20140 2Qm 20180 20170 2omo 20/100 2ol200 20/400 tkz 

u I I I I I I I I I 2o/4oo 

ALL RACES 

All ws,4.74 y..rr.... loco OR 2.4 11.7 13.2 

48 years . . . . . . . . &...........,..,...,...,.... 

511 y..rs . . . . . . . . . . . . . . . . . . . . . ..+*......... 

12.17 YW~S.,.... . . . . . . a .. . . . . . . ..o........ 

16.24 yr.rr . . ..a...... . . . . . . . . . . . . . . . . . . . . . 

25.34 yews . . . . . . . . . . ..o................... 

3544 y*.rs.... .**.. . . . . . . . . . . . . . . . . ...*... 

45.54 Y.WL . ..*.... I......... . . ..a * . . . . a. 

55.64 Y",S . . . . . . . . . . . . . . . ..*.............. 

6574 Yl.,‘....... *......1.11* . . . . . . . * . . . . . 

100.0 

100.0 

1000 

loo.0 

100.0 

100,o 

lao.o 

lW.0 

100.0 

100.0 

0.1 

0.6 

1 .o 

3: 

3.9 

2.7 

1.1 

2 

304 

72.3 

ig; 

93.2 

71.5 

58.5 

321 

7.1 

12.4 

9.E 

6.0 

10.7 

10.3 

15.1 

25.1 

23.1 

Pwant distribution of populwion 

3.0 0.8 0.4 0‘2 0.1 0.0 OR 0.D 

- 

OR 

0.0 

0.0 

OS 

0.0 

0.1 

OS 

0.1 

2a 

- 

i:: 

4.5 

fi 

3.2 

la 

l:i 

2.0 

73.6 

35.1 

74.4 

83.4 

ci 

s6.a 

75.2 

57.4 

316 

69.s 

12.2 

66.9 

10.a 

:; 

3.1 

2.6 

ii: 

16a 

7.5 

36 

E 

0.8 0.9 

ii:: 

5.2 

13.1 

2.6 

i:; 

0.5 

0.2 

0.6 

0.1 

0.6 

:I 

0.6 

0.6 

0.4 

Xi 

0.0 

0.7 

1.3 

1.4 

OS 

if 

0:r 

xi 

0.1 

OB 

0.1 

- 

0.3 

0.0 

. 

0.3 

0.2 

- 

0.4 

0.3 

:: 

0:o 

0.1 

1.3 

OR3 

- 

0.21 

8:: 

0.14 

0.01 

0.4 

0.30 

0.03 

- 

0.23 

0.06 

0.17 

OR 

0.1 

0.1 

0.1 

0.6 

0.1 

El 

0.0 

Od 

X:: 

0.0 

OR 

0.1 

0.0 

0.2 

0.0 

f&I@ 

- 

All we,, 4-74 yews ......... 

4.5 yurs.. .................................. 

6.11 yew*. ................................. 

12-17 Y.III ................................ 

16.24 y..rn ................................ 

25-34vl.r r ................................ 

3544 y..r r ................................ 

46-f% y..r s ................................ 

6644 Y.., * ................................ 

65.74 "U,‘.. .............................. 

All rplr, 4.74 y..r‘.... ..... 

4.5 MII .................................... 

6-11 YlW‘..... ............................. 

12.17 y.rrs.. .............................. 

18.24 y..r r.. .............................. 

25.34 y..r s.. .............................. 

35.44 y*.rs.. .............................. 

45.54 "III ................................ 

55.54 yew*. ............................... 

66-74 "*arc ................................ 

loo.0 

100.0 

100.0 

106.0 

100.0 

100.0 

1w.o 

1Coxl 

100.0 

100.0 0.0 

7.5 

11.7 

s; 

12.2 

8.5 

10s 

26a 

28.9 

14.4 

52.1 

6.3 

2.1 

4.1 

2.6 

1.6 

a.4 

6.0 

17.4 

6.5 

3.2 

2.4 

1.7 

8: 

0.6 

3.4 

4.0 

13.9 

3.4 

0.1 

1.0 

0.1 

X2 

1 A 

3.S 

0.9 

0.7 

0.4 

0.6 

::: 

oa 

0.9 

0.5 

0.1 

0.0 

0.0 

0.1 

0.1 

0.1 

t 

loo.0 

100.0 

1wa 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

.a. 

25.5 

70.1 

78.1 

64.6 

81.5 

60s 67.9 

66.7 

32.3 

79 

13.1 

1l.C 

iii 

12.0 

19.4 

24.1 

29.2 

59.9 

11.7 

4.4 

f :: 

a: 

9.0 

15.5 

4.3 

xi 

0.7 

1.2 

::: 

6.3 

12.6 

stmdal-d wmr 

0.62 

E 

3.13 

1 .S2 

1.51 

1.46 

E 

2:73 

2.73 

1.75 

::: 

1.24 

1.07 

1.00 

l&l 

1.93 

2.31 

l-46 

2.78 1.11 

0.76 0.62 

0.61 0.72 

0.83 0.39 

0.74 0.34 

0.79 036 

la3 0.83 

1.48 1.21 

1.45 1.27 

1.13 0.93 0.56 0.32 

4.87 1.86 

2.6S lJ7 

2.21 1.29 

2.23 1.31 

1.52 1.66 

2.01 1.74 

3.18 2.43 

3.69 3.49 

2-M 2.02 

4.31 

I% 

1:34 

0.91 

080 

1.96 

2.38 

1.78 

1.39 

0.06 

0.53 

0.52 

0.45 

0.47 

1.18 

1.17 

1.47 

0.4 

1.1 

0.5 

xi 

0.6 

OS 

5.1 

1.2 

8:: 

0.0 

OB 

2 

09 

03 

0.2 

0.1 

01 

0.0 

OR 

. 

0.1 

0.2 

0.1 

03 

OR 

0.4 

OR2 

- 

E 

0.0; 

0.1; 

0.01 

0.1 

0.0 

Od 

0.01 

- 

OR4 

0.04 

0.9; 

0.17 

0.01 

ii: 

0.8 

0.02 

- 

. 

0.02 

:s 

0.01 

Sooth "XI 

All @Se. 4.74 yun.... 

46 yurr . . . . . . . . . . . . . . ..I................... 

64 1 y*ws *... a,... . . . . . . *.......... I . . . . . . . 

12.17 Ylrn........, .,...... a,............. 

16.24 ""rr a... . . . . . . . . . . . . . ..e............ 

26.34 yaw* 1...1......1..1........ . . . . . *.a. 

3544 y..rt *...*.............*......,...... 

46.64 Year‘.... I .I.... I *..... I . . . ..I....... 

6644 YHrr *11.....*1*........*.......,.... 

66.74 y*.rs +....1..*1..1....*.* . . . . . .** . . . . 

Male 

- 

All .#nr. 4.74 y.wr . . . . . . ..I 

4-5 YIII‘..,......~.. . . . ..a. . . . . . e........... 

641 "mn ,,,.,,.. , ..,...,..,,, .,,...,.a.... 

0.12 

- 

x2 

0.211 

0.16 

0.21 

0.00 

0.29 

0.53 

0.90 

0.09 

0.11 

- 

0.42 

0.21 

0.07 

0.19 

0.01 

0.36 

0.77 

0.40 

0.19 

0.04 0.01 

0.37 . 

:z 

0.1; . T 0.02 

L 

0.M 0.03 

0.95 0.07 

0.30 0.02 

*.. 

. . . 

.I. 

. . . 

.I. 

a.. 

..a 

.a. 

..I 

..* 0.04l 0.01 

. . . 

*.. 

. . . 

*.. 

..I 

. . . 

. . . 

.a. 

.*. 

0.06 

0.90 

0.11 

0.09 

0.58 

0.90 

1.12 

0.4; 

0.41 

0.u 

1.19 

0.62 

0.M 

0.W 

0.22 

0.00 

0.16 

0.05 - 

* 0.05 

* I 

. 

0.4; 0.01 - 

12-17 ..................................... 

18.24 y..r‘.......... ...................... 

25.34 "..rr ................................ 

3544 y..r l ................................ 

45-54 Yllll ................................ 

55.64 "llll.............. .................. 

66.74 y*m ................................ 

Su footnotes .t end of table. 

53 
Table 25. Percent distribution and number of population age 4.74 yearsby maximum visual acuity levels reached in the better eye with usual correction for those testing 20140 or better 

andwithaddirionslcorraction on spherical refraction orrainorcopy for the rsmaindsrshown,by age,sex,and raca,with standardsrrors: UnitedStater,1971-1972-Con. 

Age,rsx,snd race1 

LWS 

Total 20/10 20/15 20/20 20/25 20130 20/40 20150 20/M) 20170 20180 2OllOO 20/200 201400 than 

201400 

Standard error 

ALLRACES-Con. 

Female 

All ager.4.74 years . . . . . . . 0.02 1 0.39 0.42 0.19 0.09 

--- 

1.39 - 0.86 

0.91 0.32 0.07 

1.25 0.56 0.13 

0.34 0.29 - 

0.50 0.39 0.02 

0.53 0.04 . 

1.21 0.28 0.57 

1.88 0.63 0.58 

1.63 1.06 0.42 

Numberinthousands2 

. 

6 

26 

76 

62 

6-11 yews .................................. 

12.17 years ................................ 

18.24 years ................................ 

26.34 years ................................ 

3644 ye*,* ................................ 

46.54 yew‘................................ 

55.64 WQ,‘................................ 

65-74 years................................ 

. . 

. . 

. 

. . 

. 

. . 

Both sexes 

All sger.4.74 years.... 182,240 

6 

. 0.49 

. 0.43 

0.79 

. 1.10 

0.14 1.08 

. 0.66 

. 0.61 

. 0.85 

- 0.24 

1.68 

2.67 

3.16 

3.27 

2.00 

I 

0 69 1.04 

1.92 1.26 

2.31 1.72 

3.30 

I 

1.88 

2.22 1.79 

4-6 years.................................... 6,776 

6.11 years . . . . . . . . . . . . . . . . . . . . . . . . . . . 23,652 

12-17 Year‘................................ 24,599 

18-24 years ................................ 24,236 

25.34 years ................................ 26,035 

35.44 VBar‘................................ 22,354 

45.54 ye*,* ................................ 23,307 

55.64 ysarr ................................ 18,830 

65.74 years ................................ 12.453 

4,360 24,227 5,617 

3.787 

;!,366 

812 

800 

607 

626 

1.748 

1,696 

2,030 

6,615 

284 182 

MalO 

- 

All agss. 4-74 ysar‘......... 88,162 

54 

237 

812 

1,018 

1,015 

604 

256 

264 

100 

2.473 

2,060 

17,100 

19,861 

20,562 

21,036 

18,621 

16,641 

10,639 

3,998 

64,832 

522 

2,933 

2,361 

1.454 

2,786 

2,302 

3,619 

4.726 

3,624 

257 

686 

566 

194 

234 

201 

769 

379 

1,631 

2.326 

- 

110 

289 

212 

32 

75 

64 

380 

364 

752 

2 

166 

123 

48 

130 

22 

140 

207 

560 

544 

- 

3 

120 

13 

A: 

124 

206 

878 

41 

96 

26 

48 

2 

163 

245 

174 

a4 

46 

14 

71 

25 

48 

3 

23 

100 

24 

23 

19 

76 

68 

46 years .................................... 

6.11 years.. ................................ 

12-17 years ................................ 

18.24 years.. .............................. 

25.34 wars ................................ 

36-44 years ................................ 

4554 years ................................ 

55.64 ye*,* ................................ 

65.74 years ................................ 

Female 

3,452 

12,046 

12.488 

11.467 

12,660 

10,740 

11,165 

8,846 

5,409 

All ages, 4-74 years.. ....... 94,078 

35 

145 

562 

573 

540 

344 

146 

97 

32 

1,216 

8,974 

10,416 

3,736 

10,062 

9,247 

8,396 

5.077 

1.720 

269 

1,409 

1,024 

562 

1,631 

913 

1,172 

2,326 

1,563 

1,798 

1,000 

262 

470 

326 

172 

938 

708 

941 

230 

27 

124 

4-6 years .................................... 

6.11 wars.. ................................ 

12.17 years ................................ 

18-24 "ears ................................ 

25-34 years ................................ 

3544 year‘................................ 

46-64 ye=rs ................................ 

5664 ye*,* ................................ 

66.74 years ................................ 

3,323 

11,607 

12,111 

12,768 

13,485 

11,614 

12,142 

9,984 

7.044 

Bothsexes 

All ages.4.74 yews.... 100.0 

17 

104 

266 

434 

472 

256 

121 

170 

70 

847 

8,136 

9.446 

10,815 

10,964 

9,372 

8,245 

5,561 

2,275 

263 

1.520 

1,332 

919 

1.254 

1,394 

2,356 

2,406 

2,067 

13.1 

1,987 

1.368 

533 

332 

485 

453 

801 

978 

1,092 

143 

395 

361 

89 

162 

128 

401 

629 

888 

46 

133 

64 

108 

6 

73 

so 

359 

13 

35 

24 

51 

3 

24 

10 

42 

0.6 

26 

6 6 

20 

42 

Percent distribution of population 

0.4 

- 

- 

0.4 

0.4 

0.1 

0.2 

0.8 

1.2 

1.1 

2.3 I 72.3 7.9 2.9 0.8 0.2 0.0 

0.2 

03 

0.1 F 0.2 

0.1 I 0.7 

0.0 

0.0 

0.6 

0.1 

0.2 

100.0 

100.0 

100.0 

100.0 

100.0 

loo.0 

100.0 

100.0 

loo.0 

8.0 53.9 3.2 

10.7 3.3 2.2 

8.5 3.1 2.4 

6.1 3.3 0.5 

9.9 3.0 1.0 

9.9 2.6 0.7 

15.3 7.3 2.7 

25.7 8.3 5.3 

30.0 15.5 12.7 

0.7 

0.6 

0.1 

0.5 

0.0 

0.6 

1.2 

4.2 

0.9 33.0 

0.9 75.5 

3.4 81.8 

4.0 65.5 

3.8 B1.7 

2.6 64.4 

1.3 72.0 

1.4 56.8 

0.9 33.4 

6-11 yearr .................................. 

12.17 ye*,* ................................ 

18-24 years ................................ 

25-34 yes,‘................................ 

3544 years ................................ 

45.54 years ................................ 

56.64 yexs................................ 

65.74 years ................................ 

S-se footnotesat end of table. 

0.1 

54 
Table25. Percent distribution and number of pqaulation qe 4-74 ysarsbymaximumvisualacui~le~lsr~schedinthskmra~~with usu(~Icorrection forthovtaninS20/40orbsnar 

and with sdditionrlcorrection on spherical refraction or retinoscopv fortha remainder shown,by s9+tax,~1d nce.with stmd.srd wrors:Unitd Stites,1971-1972-&n. 

LOX 

Total 20/10 ml15 20/20 20125 20/30 20140 20/50 mm 20170 mb30 201100 m/zoo mm0 than 

mm3 

ASs.rax,and race1 

Percant distribution of population 

WHITE-Con. 

All spar.4.74 years . . . . . . . . . 

4-5 years.................................... 

6-l 1 wars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

2.7 

- 

1.i 

0.E 

4.E 

4.c 

4.i 

2.E 

1 .E 

1.1 

0.E 

1 I 

12.0 

36.7 

76.0 

84.3 

as.2 

81.8 

86.7 

77.0 

57.3 

33.0 

7.8 

10.9 

7.4 

49 

10.6 

8.3 

10.4 

27.2 

30.3 

28.8 8.2 

74.9 10.5 

79.0 9.7 

85.6 7.2 

81.7 9.3 

81.7 11.4 

67.2 19.9 

56.4 24.4 

33.4 29.8 

15.4 

7.3 2.4 0.6 

51.4 2.4 - 

7.8 2.5 1.0 l-t 1.8 1.6 - 

4.2 0.7 - 

2.2 0.7 0.0 

1.5 0.5 0.1 

lw.o . 0.1 0.0 

100.0 - 

loo.0 - 

100.0 . 

1OQ.o - 

100.0 . 

100.0 - 

100.0 . 

loo.0 . 

100.0 - 

88 

100.0 0.0 

100.0 - 

lW.0 - 

100.0 - 

100.0 - 

100.0 0.1 

100.0 . 

100.0 - 

loo.0 - 

100.0 - 

0.5 0.1 

0.0 

0.0 0.0 

0.7 

0.4 

8.0 1.9 0.6 0.6 

7.0 4.2 1.4 1.8 

16.6 13.0 3.5 1.6 

0.3 

0.2 

02 

0.4 

0.6 

0.1 

0.1 

0.1 

0.1 

0.5 

0.1 

12-17 ysar‘................................ 

18-24 yssrs ................................ 

25.34 yesrs.......................: ........ 

3544 yslr‘................................ 

45-54 y~,ar‘................................ 

55.64 ysars ................................ 

65-74 years ................................ 

Female 

All aw, 4.74 years.. ....... 

4.5 ysars .................................... 

6.11 yc*n .................................. 

12-17 yaars ................................ 

18.24 yalrr ................................ 

25-34 YB~~S ................................ 

3544 Ylll‘................................ 

45.54 ymrs ................................ 

6544 ymm ................................ 

65-74 ysars ................................ 

SLACK 

Both sexes 

Allsgas.4-74 yasrs .... 100.0 0.0 

4.5 YIPS'.................................... 

6.11 y~~lrs .................................. 

12-17 yam‘ ................................ 

18-24 yew‘ ................................ 

25.34 ~.ln ................................ 

3544 y~lr‘................................ 

45-54 yalr‘................................ 

55.64 yllr‘................................ 

65.74 y*ars ................................ 

w 

loo.0 

100.0 

1ooa 

loo.0 

loo.0 

1 w.0 

100.0 

loo.0 

lW.0 

All spss.4.74 yews ......... 

4-5 Yllr‘.................................... 

6-11 yaws .................................. 

1217 yeses ................................ 

18.24 years ................................ 

25.34 ys~r‘................................ 

3544 y*ars ................................ 

45-54 YIlr‘................................ 

55-64 yl~r‘................................ 

65-74 yaarr ................................ 

Female 

loo.0 

0.1 

All aw‘. 4.74 "ssn ......... 

45 yllr‘.................................... 

6-11 yews .................................. 

12.17 yl.r‘................................ 

18.24 ysws ................................ 

25.34 yl*r‘................................ 

3544 ye.r* ................................ 

4554 wars ................................ 

loo.0 

lW.0 

loo.0 

loo.0 

100.0 

100.0 

100.0 

100.0 

lW.0 

loo.0 0.0 

loo.0 

loo.0 

loo.0 

loo.0 

loo.0 

loo.0 

loo.0 

100.0 

loo.0 

02 

0.E 

1x 

1.9 

3 

2.1 

1.1 

1.5 

1.1 

2.6 

10.8 2.0 0.4 

4.5 3.2 1.2 

2.4 0.3 0.2 

0.8 

0.1 

0.2 

6.7 3.5 0.4 0.9 

9.6 6.2 1 a 0.6 

14.7 12.5 4.7 0.8 

0.5 

0.3 

0.3 

0.4 

0.1 

1.1 

0.3 

0.1 

0.1 

0.6 

0.4 

0.0 

0.1 

0.2 

0.3 

0.4 

0.0 

0.1 

0.6 

0.0 

0.2 

0.3 

0.2 

Percent distribution of population 

10.9 4.7 0.9 0.4 0.1 

1.9 

2.2 

5.1 

4.6 

4.7 

1.7 

0.2 

3.0 

13.3 6.2 

54.2 22.5 

76.6 15.6 

82.3 6.0 

74.3 15.8 

73.8 14.7 

66.9 13.7 

53.4 21.6 

19.6 19.8 

69.5 

14.1 

2 

ai 

8:5 

14.2 

25.0 

2: 

2.0 

2.2 

0.4 

22 

8.4 

5.4 

18.0 

0.2 

0.2 

0.2 

1.1 

0.6 

0.2 

1.3 

0.4 

7.6 

1.7 

0.3 

0.1 

0.1 

0.4 

4.0 

0.1 

0.2 

1.8 

67.1 13.3 9.9 4.9 0.7 0.6 0.1 

3.1 

2.8 

7.0 

1.4 

8.3 

0.3 

19.8 5.8 59.5 

65.3 16.9 11.5 

81.2 11.3 2.0 

85.0 4.4 1.2 

70.4 21.8 5.6 

74.8 11.4 3.2 

60.5 11.9 11.0 

63.4 17.1 14.4 

17.3 15.3 26.9 

9.7 

2.1 

2.4 

1.6 

08 

0.5 

2.3 

15.4 

1.8 

24.0 

0.8 

OS1.d 

6.2 

2.3 61.5 17.1 11.8 4.6 1.2 

2.0 

0.8 

0.5 

0.9 

0.5 

02 

8:: 

1.5 

0.5 

0.1 

02 

0.2 

0.1 

Od 

0.0 

0.2 

0.5 

2.5 

0.1 

0.6 

0.2 

0.9 

7.7 

0.2 

0.4 

0.5 

0.2 

4.7 

0.5 

0.3 

0.3 0.1 

0.8 

0.0 

1.1 

1.3 

0.2 

0.6 

1.6 

2.8 

Z:i 

2.8 

0.4 

8.8 

43.5 

72.4 

79.9 

77.8 

73.3 

72.9 

45.7 

21.3 

19.7 

7.3 

10.2 

16.2 

15.5 

25.1 

23.0 

76.5 

16.6 

4.3 

3.7 

2.6 

4.9 

6.0 

14.0 

23.8 

1::: 

1.6 

2.7 

:z 

1.6 

a.2 

13.5 

0.4 

2.1 

0.4 

0.4 

2.0 

a.7 

2.8 

0.1 

12 

0.2 

2.8 

0.2 

1.5 

1.0 

1.6 

0.8 

0.2 

2.6 

0.8 

0.5 

0.4 

0.1 

0.5 

3.3 

55-64 Ylll‘................................ 

65.74 "srn ................................ 

Se‘ footnote‘stend oftsble. 

55 
Table 25. Percent distribution and number of population age 4-74 yearsby maximumvisuslacuity levelsreachedinthebettereyewith usual correction forthosstesting 20140orbetter 

and with additional correction on spherical refraction or retinoxopy for the remaincler rhown,by age,sex,and race,with standard errors: United States,1971-1972-Con. 

,.I/,,,,lj,,,,O 20/40 20/50 20/60 20/70 20/80 20/100 20/200 20/4W 20/400 than Len 

Age,rex,andrace' 

WHITE 

Both sexes 

All ager.4.74 years.... 

4-5 years.................................... 

6-11 vears 

0.01 

= 

0.08 

0.49 0.30 0.12 0.04 0.03 0.01 0.03 0.02 

- 

. . . 

. 

.- 

.- 

. . . 

.- 

. 

. 

. . . 

0.50 1.01 0.70 

E 

0.53 3.31 1.94 3.10 1.14 

0.29 1.95 1.61 0.76 0.49 

1.03 1.88 1.26 0.76 0.81 

1.25 1.41 1.14 0.95 0.30 

1.13 1.43 1.19 0.80 0.39 

0.74 1.95 1.48 0.84 0.36 

0.62 3.17 2.13 1.62 0.78 

0.74 2.75 2.51 1.52 1.30 

0.31 1.85 1.67 1.56 1.39 

0.71 

- 

1.20 0.95 0.57 

-- 

0.32 0.11 0.23 0.03 

0.81 5.26 2.06 5.25 1.23 

0.19 2.97 2.08 i .4a 0.91 

1.61 2.28 1.32 0.71 0.55 

1.57 2.28 1.51 1.55 0.59 

2.04 1.91 2.19 1.02 0.52 

0.90 2.10 1.90 0.86 0.49 

031 3.44 2.46 2.29 092 

1.10 3.82 3.79 2.16 1.25 

0.48 2.23 2.28 1.76 1.57 

0.34 1.25 0.73 030 0.42 0.21 

- - 

0.13 0.02 

0.57 

0.32 

0.09 

0.24 

0.05 

0.37 

0.58 

036 

0.42 0.24 

0.27 0.05 

0.08 0.14 

0.22 0.16 

0.40 

0.76 

0.36 

0.06 

0.32 

0.27 

0.04 

0.04 

0.33 

0.04 

0.02 

0.04 

0.05 

0.16 

0.14 

0.01 

0.05 

0.04 

0.19 

0.02 

0.13 

0.16 

0.01 

12-17 years.. .............................. 

18-24 years.. .............................. 

25-34 yelps ................................ 

3544 years.. .............................. 

45.54 years.. .............................. 

55.64 years ................................ 

65-74 yelps ................................ 

Male 

- 

All ages, 4.74 yews ......... 

4.5 yBBr* .................................... 

6.1 1 years .................................. 

12.17 y.?ws ................................ 

18.24 Yeats ................................ 

25.34 Yeats ................................ 

3544 years ................................ 

45.54 years ................................ 

55.64 years ................................ 

65.74 years ................................ 

Female 

All ager.4.74 yssrr ......... 

4.5 years .................................... 

6.11 years .................................. 

12.17 years ................................ 

18-24 yews.. .............................. 

2544 years.. .............................. 

3544 years ................................ 

45.54 years.. .............................. 

55s4 pm* ................................ 

65-74 years.. .............................. 

1.06 0.52 

0.48 

0.05 

0.10 

0.64 

097 

1.24 

0.49 

1.28 

0.42 

0.09 

0.38 

0.65 

0.18 

0.45 

0.90 

0.08 

0.16 

0.41 0.64 

0.70 0.49 

1.10 0.56 

0.27 

0.19 

0.08 

- 

0.51 

0.34 

0.27 

0.31 

0.12 

0.55 

0.04 

0.53 

0.04 

- 

0.36 

0.07 

0.07 

0.39 

0.02 

0.05 

0.07 

0.10 

0.05 

0.09 

0.26 

0.02 

-. 

-. 

. . . 

. . . 

. . . 

. . . 

. . . 

. . . 

. . . 

-. 0.02 

1.64 

0.54 

1.43 

0.21 

0.56 

0.51 

1.35 

1 so 

1 as 

0.31 

0.24 

0.09 

029 

0.24 

0.25 

.- 

.- 

.- 

.- 

.- 

. . . 

0.15 

0.59 5.39 2.56 

0.51 2.15 2.01 

0.74 325 2.02 

1.25 134 1.36 

0.94 1.61 0.83 

0.83 2.91 1.92 

0.58 3.90 2.76 

0.89 3.30 3.37 

0.23 2.23 2.50 

5.03 

2.03 

1.28 

0.91 

1.14 

::: 

2.14 

2.03 

SLACK 

Both sexes 

All ages.4.74 years.... 

Standard error 

0.82 0.08 0.24 0.08 0.03 0.01 0.12 

- 

1.60 

3.90 

5.08 

4.17 

3.70 

3.88 

5.4D 

5.34 

7.94 

3.94 

1.15 0.48 

-- 

-- 

4.48 

1.91 

0.53 

- 

0.20 

= 

2.83 0.21 

2.15 0.16 

1.12 0.21 

1.30 038 

0.22 0.41 

0.96 0.24 

3.54 0.65 

2.09 0.32 

2.22 1 a6 

1.20 0.21 

0.11 

- 

- 

1.39 

0.23 

0.08 

0.09 

0.44 

1.15 

0.22 

1.98 

0.10 

0.19 

0.02 

0.45 

0.17 

0.48 

2.04 

0.09 

4-5 yeas .................................... 

6-l 1 "ear‘. ................................. 

2.63 

3.98 

3.49 

2.11 

2.87 

3.43 

2.34 

0.92 

12-17 yeas* ................................ 

16.24 v~ars ................................ 

0.93 

2.65 

2.72 

2.38 

1.47 

091 

1 a4 

0.96 

25-34 ;B~,s ................................ 0.12 

3544 yean ................................ 

45.54 yBBn ................................ 

5564 years ................................ 

65.74 years.. .............................. 

MCJl.3 

- 

All ages. 4-74 years.. ....... 

4-5 years .................................... 

B-11 year‘.................................. 

12-17 dears ................................ 

18.24 ye~,s ................................ 

25-34 years ................................ 

35-w years ................................ 

45.54 years ................................ 

55.64 years ................................ 

65-74 years ................................ 

See footnotes at end of table. 

1.61 

1.81 

4.59 

2.40 

0.21 0.49 

0.78 

0.60 

0.23 

0.91 

0.26 

1.49 

0.24 

6.80 

3.57 1.22 

0.07 

0.19 

1.29 2.92 2.52 0.81 

-- 

8.14 

2.94 

1.22 

1.03 

021 0.06 

7.84 

5.99 

5.28 

8.30 

5.70 

933 

3.78 

4.59 

4.97 

2.94 

5.66 

5.26 

4.23 

7.38 

2.66 

4.70 

la4 

1.90 

1.37 

1.59 

6.66 

1.55 

4.60 

0.52 

0.34 0.50 

086 

0.62 0.20 

0.69 1.03 

2.18 326 

4.80 

2.19 

1.26 

528 

1.01 

7.27 

0.35 

3.31 

2.12 

7.30 0.43 

9.25 

3.79 

2.56 

9.36 

5.39 

0.36 

0.37 

56 
Table 25. Percent distribution and number of Population ege 4-74 veers bv maximum visual acuity levels rerched in the better eve with usual correction for those testing 20140 or better 

and with edditional correction on spherical refraction or retinascopy for the remainder shown, by age, sex, and race, with standard errors: United States. 1971.1972~Con. 

Age, sex, and recel Total 

Less 

20110 20115 20120 20/25 20130 20140 20/50 20/6X1 20170 2Ol80 2OIlW 201200 20/4OO then 

2014W 

BLACK-Con, 

Female 

All eger, 4-74 veers . . . . . . . . . - 11 0.02 

4-5 w*rs.. .................................. - . 

6.11 yaars.. ................................ - . 

12-17 yesrs ................................ - . 

18-24 ysars .......... . ..................... - . 

25-34 years ................................ - 0.17 

3544 years.. .............................. - . 

45.54 Ye.r‘................................ - . 

1 1 I 

3.64 I 6.22 I 291 I . 

4.44 

529 

2.29 

3.04 

4.74 

3.89 I 4.74 

2.43 089 

1.36 184 

65-74 ye.,:::::::::::::::::::::::::::::::: 1 

5561 ;e*n 

1 11 : 

425 

8.64 

5.35 

1.98 1.13 

4.82 I 5.58 

3.29 3.39 

. 

0.41 

1.69 

024 

0.36 

1.24 

3.04 

0.13 

228 

0.15 

1.07 

0.23 

I II 

lTot.1‘ include races other than white and Slsck. 

2B~csu~ of rounding wlthin the individual cells, the populstion estimates for the totels will not in so instsnces equsl the sum of so the respective vslucr shown. 

0.21 

Table 26. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye1 and difference between this maximum 

and usual visual acuity, by age, sex, and race: United States, 1971-1972 

Maximum visual acuity Difference between maximum and usual visual acuity 

20120 or better I 20/50 or less 20120 or better 20/50 or less Age and sex 

All All All All 

races2 White Black races2 White Black races2 White Black races* White Black 

Both sexas Percent of population Difference in percent 

All ages, 4-74 years . . . . . . . . . . . . . . . . . . 74.0 74.7 66.7 1.6 1.5 2.3 1.2 1.2 0.9 -1.7 -1.6 -2.8 

4-5 years .................................................. 31.2 

6-l 1 years.. .............................................. 73.4 

12-17 years.. ............................................ 84.0 

1844 years.. ............................................ 88.4 

45-54 years.. ............................................ 72.5 

55-64 years.. ............................................ 57.9 

65-74 years.. ............................................ 32.9 

33.9 

76.3 

85.1 

87.1 

73.2 

2:: 

13.3 1 A 1.1 

56.0 1.4 1.5 

78.8 0.8 0.9 

81.9 0.5 0.4 

66.9 1.5 1.4 

55.0 2.8 2.5 

19.8 8.5 7.6 

3.9 

0.7 

0.3 

?I:: 

3.7 

17.4 

Male 

- 

All ages, 4-74 years.. ..................... 76.2 77.0 70.1 1.3 1.3 1.8 

0.0 

0.9 

1.2 

0.7 

1.3 

1.9 

0.9 

1.0 

0.9 

1.1 

0.8 

1.6 

1.6 

1.0 

0.1 

0.3 

2.0 

0.9 

1.7 

0.7 

-0.5 -0.1 -3.2 

-2.1 -2.2 -1.5 

-1.9 -1.5 -3.1 

-1.0 -1.0 -1.5 

-1.7 -1.5 -3.7 

-1.9 -1.5 -3.9 

-5.6 -5.2 -10.2 

1.2 0.9 -1.6 -1.6 -2.8 

36.2 37.9 19.8 1.0 0.5 5.2 0.0 -0.1 

75.6 76.7 68.3 1.9 2.1 1.2 0.6 0.8 0.5 -2.0 -2.1 -1.2 

87.8 89.0 83.9 0.1 0.1 0.3 1.2 1 .o 2.8 -2.2 -1.6 -3.2 

87.8 88.5 82.2 0.2 0.2 0.3 1.1 1.1 0.1 -1.0 -1.1 -0.5 

76.5 78.4 60.5 1.2 1.3 1.2 1.4 1.5 -1.9 -1.1 -7.4 

58.5 58.4 63.6 3.2 3.2 3.1 1.6 1.5 0.5 -2.0 -1.9 -2.9 

32.3 33.6 17.2 7.4 6.5 16.6 0.8 0.8 0.2 -6.1 -5.3 -13.8 

71.5 72.5 63.9 1.9 1.7 2.7 1.0 1.0 0.7 -1.7 -1.6 -2.6 

26.0 29.4 8.8 2.0 1.7 3.0 0.0 -0.8 -5.4 

71 .o 75.9 44.1 0.8 0.9 0.2 0.9 1.1 0.2 -2.3 -2.4 -1.9 

80.1 81 .O 74.0 

l:Z 

1.7 0.4 0.9 1.1 1.4 -1.6 -1.5 -2.8 

85.2 85.7 81.6 0.7 1.6 0.6 0.3 0.5 -1.0 -0.8 -2.1 

68.9 68.4 73.0 1.8 1.6 3.9 1.6 -1.6 -1.8 -0.1 

57.4 58.0 48.4 2.5 1.8 4.2 ::‘: 1.9 2.6 -1.6 -1.3 4.3 

33.4 34.6 21.7 9.4 8.5 18.2 1.1 1.1 0.9 -5.2 -5.0 -7.3 

4-5 years.. ................................................ 

6-11 years.. .............................................. 

12-l 7 years.. ............................................ 

18-44 years.. ............................................ 

45-54 years.. ............................................ 

55-64 years.. ............................................ 

65-74 years.. ............................................ 

Female 

All ages, 4-74 years . . . . . . . . . . . . . . . . . . . . . . . 

4-5 years.. ................................................ 

6-11 years.. .............................................. 

12-l 7 years.. ............................................ 

18-44 years.. ............................................ 

45-54 years.. ............................................ 

55-64 years.. ............................................ 

65-74 years.. ............................................ 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spherical refraction or 

retinoscopy for the remainder. 

*Totals include races other than white and Black. 

57 
Table 27. Percent of population age 4-74 years roaching spscifitd maximum visual acuity lswls in the better r~ye,~ by annual family 

income, age, race, and sex, with standard errors: United States, 1971.1972-Con. 

Age. race,2 and sex Unde, 2°‘::::ne;10 00;; 

$5,000 $9,999 andbvor $5,009 $9:999 and @over $5,000 $9,999 sndbver 

Female-Con. Percent 

All races, 65-74 years . . . . . . . . . 31.0 41.6 32.2 68.4 51.3 61.3 105 7.1 6.5 

White . . . . . . . . . . . . . . . . . . . . . . . . . ..*................ 33.0 41.5 32..7 56.8 52.5 60.9 10.3 6.4 

Black . . . . . . ...*........................*.......*.. 18A 44.4 . . 69.0 29.3 l 86.3 12.6 V3.7 

See footnotes at end of table. 

60 
Table 27. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye,l by annual family 

income, age, race, and sex, with standard errors: United States, 1971-1972-Con. 

26120 or better I 20/25-26140 I 20150 or less 

Age, race,* and sex Under $5,000- $10,006 Under $5,006 $10,000 Under $5,000- $10,000 

$5,000 $9,999 and over $5,000 $9,999 and over $5,000 $9,999 and over 

Both sexes Standard error 

Total 4-74 years.. ......... 2.02 1.30 1.63 1.57 1.32 1.70 

All races, 45 years.. ........... 

White ............................................ 

Black.. ........................................... 

All races, 6-11 years.. ......... 

White ............................................ 

Black.. ........................................... 

All races, 12-l 7 years ......... 

White ............................................ 

Black.. ........................................... 

All races, 1844 years ......... 

White ............................................ 

Black.. ........................................... 

All races, 45-54 years ......... 

White ............................................ 

Black.. ........................................... 

All races, 5564 years.. ....... 

White ............................................ 

Black ............................................. 

All races, 65-74 years.. ....... 

White ............................................ 

Black.. ........................................... 

Male 

7.42 4.62 3.90 8.06 4.64 3.69 

11.96 4.98 3.78 11.96 4.97 3.58 

7.60 3.14 3.97 9.06 3.31 3.97 

4.52 3.62 2.57 3.48 3.70 2.46 

5.99 3.96 2.81 4.76 3.97 2.67 

5.32 7.47 14.17 5.03 7.67 14.17 

5.64 3.06 1.42 5.31 2.95 1.62 

8.47 3.50 1.54 7.80 3.41 1.74 

3.97 8.95 7.01 4.37 9.00 7.01 

2.23 1.40 1.64 2.05 1.26 1.64 

2.61 1.61 1.58 2.53 1.46 1.58 

3.69 283 7.47 3.63 2.58 7.47 

5.52 4.26 3.60 4.47 4.55 3.70 

9.24 4.59 3.73 7.41 4.96 3.83 

8.35 10.76 7.55 6.86 11.02 7.56 

7.20 3.78 4.64 6.38 3.83 4.91 

7.35 4.03 4.32 6.79 4.03 4.64 

10.01 14.68 20.79 11.66 15.10 20.79 

2.01 2.91 4.75 1.75 3.79 5.14 

2.10 3.13 5.11 1.78 4.14 5.45 

5.33 10.68 5.51 3.67 12.96 5.97 

0.74 0.32 0.20 

1.83 0.47 0.66 

0.53 0.69 

444 0.62 

2.54 0.54 0.64 

3.92 0.62 0.67 

0.48 0.68 

0.64 0.53 0.51 

1.00 0.64 0.54 

0.53 0.53 

0.39 0.28 0.06 

0.44 0.30 0.06 

0.99 0.93 

3.05 1.15 0.38 

4.17 1.30 0.40 

2.07 0.99 0.39 

2.49 1.17 1.01 

3.31 1.13 1.05 

2.81 2.49 

2.06 1.60 1.35 

2.08 2.08 1.41 

3.74 1280 4.13 

Total, 4-74 years.. ......... 2.36 1.77 1.94 2.31 1.63 2.02 

All races, 45 years ............. 

White ............................................ 

Black.. ........................................... 

All races, 6-11 years ........... 

White ............................................ 

Black.. ........................................... 

7.71 7.98 5.67 9.55 8.00 5.68 

13.02 8.88 5.83 13.02 8.90 5.85 

11.68 6.48 l 15.81 13.49 6.75 V5.81 

6.75 5.06 4.11 5.57 4.79 3.82 

Al I races, 12-l 7 years ......... 

White ............................................ 

Black.. ........................................... 

Smfootnotes at end of table. 

1.00 0.45 0.29 

3.59 0.89 0.19 

0.96 0.20 

8.56 1.68 l . 

4.25 1.05 0.87 

6.28 1.21 0.92 

0.97 1.55 

-l--k 

0.67 

1.16 

1 .oo 

61 
Table 27. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye,l by annual family 

income, age, race, and sex, with standard errors: United States, 1971-1972-Con. 

0.03 

-- 

20120 or better 20/25-20140 I 20150 or less 

Age, race,2 and sex Under $5,000- $10,000 

I I 

Under $5,000- $10,000 Under $5,000- $10,000 

$5,000 $9,999 and over $5,000 $9,999 and over $5,000 $9,999 and over 

Male-Con. Standard error 

All races, 1844 years ......... 3.31 2.60 2.3'2 3.27 2.40 2.32 0.13 0.36 

White ................ , ........................... 3.44 2.83 2.26 3.40 2.61 2.26 0.19 0.42 

Black.. ........................................... 8.04 5.74 12.41 8.04 5.30 12.41 0.87 

All races, 45-54 years ......... 9.26 3.95 4.67 7.75 4.34 4.67 7.71 1.72 

White ............................................ 15.51 5.12 4.41 9.39 5.52 4.41 12.69 2.14 

Black.. ........................................... 11.83 14.76 26.16 11.66 14.76 26.40 3.22 1 .Ol 

All races, 55-64 years ......... 9.48 5.49 4.91 8.18 5.33 4.77 6.86 1.09 

White ............................................ 8.15 6.59 5.00 7.54 5.50 4.85 8.02 1.16 

Black.. ........................................... 24.68 19.58 l 20.24 22.40 19.73 *20.24 2.68 5.39 

All races, 65-74 years ......... 3.18 3.64 4.87 2.72 5.01 5.63 2.14 3.47 

White ............................................ 3.22 3.79 5.1'9 2.95 5.26 5.96 1.91 3.60 

Black ............................................. 4.94 5.22 "7.09 3.68 7.18 *7.09 6.65 5.05 

Female 

1.18 

1.84 

-- 

1.90 

*m 

1.85 

1.94 

*- 

Total, 4-74 years.. ......... 2.83 1.39 1.81 2.50 1.50 1.84 0.81 0.46 0.28 

All races, 4-5 years ............. 9.71 6.12 7.37 9.69 6.12 7.09 0.23 

White ............................................ 

Black.. ........................................... 

All races, 6-1 1 years.. ......... 

White ............................................ 

Black.. ........................................... 

All races, 12-I 7 years ......... 

13.42 7.62 7.57 13.42 7.62 7.27 

9.90 2.32 a'. 9.97 2.32 *- 0.60 

5.78 4.07 3.04 5.78 4.10 2.99 0.32 

-- 

6.12 4.39 3.3!3 6.12 4.43 3.33 0.38 

7.10 8.24 l 19.of3 7.10 8.19 *lg.08 0.59 

7.48 4.29 3.23 6.79 4.22 3.58 0.94 0.97 

1.34 

-- 

1.46 

*e 

0.95 

1 .oo 

+e 

1.08 

White ............................................ 

Black.. ........................................... 

11.01 6.31 3.4:2 9.93 6.20 3.81 1.40 1.24 

4.16 12.49 16.18 4.16 12.58 16.18 0.87 

All races, 18-44 years ......... 2.87 1.73 1.70 2.58 1.74 1.71 0.63 0.42 

1.11 

0.11 

White ............................................ 

Black.. ........................................... 

3.58 1.70 1.72 3.40 1.68 1.73 0.69 0.44 

3.39 3; .45 7.73 3.33 3.93 7.73 1.61 1.37 

0.12 

All races, 45-54 years ......... 8.20 6.33 4.76 7.22 6.94 4.88 2.41 1.56 0.81 

White ............................................ 11.24 7.01 5.48 9.25 7.78 5.62 3.49 1.65 

Black.. ........................................... 11.15 17.84 10.35 8.25 18.53 10.35 4.86 1.92 

0.89 

All races, 5564 years ......... 

White ............................................ 

Black.. ........................................... 

8.34 5.26 9.3:! 7.44 5.59 9.32 1.79 2.14 

-. 

8.70 5.15 9.08 7.55 6.12 9.08 2.30 2.01 

14.42 16.00 +34.13 17.04 16.00 *34.71 3.71 

See footnotes at end of table. 

62 
Table 27. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye,l by annual family 

income, age, race, and sex, with standard errors: United States, 1971-1972-Con. 

20120 or better 20/25-20140 20150 or less 

Age, race,* and sex Under $5,000- $10,006 Under $5,OOC- $10,000 Under $5,600- $10,000 

$5,000 $9,999 and over $5,006 $6,966 and over $5,006 $9999 and over 

Female-Con. Standard error 

All races, 65-74 years . . . . . . . . . 2.13 4.36 6.14 2.60 4.74 6.89 2.43 1.49 2.52 

White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.59 4.66 6.34 3.10 4.99 7.07 2.58 1.51 2.64 

Black . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.49 16.91 l m 6.42 9.38 l 35.1 5 2.93 18.98 *I 2.03 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spherical 

refraction or retinoscopy for the remainder. 

‘Totals include races other than white and Black. 

63 
Table 28. Difference between maximum and usual visual acuity levels in the better eye1 among population age 4-74 years, by annual 

family income, age, race, and sex: United States, 1971-1972 

Age, race,* and sex 

Both sexes 

Total, 4-74 years ................................................................ 

All races, 4-5 years .................................................................. 

White ................................................................................................. 

Black .................................................................................................. 

All races, 8-11 years ................................................................ 

White ................................................................................................. 

Black .................................................................................................. 

All races, 12-l 7 years ........................................... . .................. 

White ................................................................................................. 

Black.. ................................................................................................ 

All races, 18-44 years .............................................................. 

White .................................................................................................. 

Black.. ................................................................................................ 

All races, 45-54 years .............................................................. 

White ................................................................................................. 

Black.. ................................................................................................ 

All races, 5564 years .............................................................. 

White ................................................................................................. 

Black.. ................................................................................................ 

All races, 65-74 years ......................................................... .: ... 

White ................................................................................................. 

Black.. ................................................................................................ 

Male 

- 

Total, 4-74 yean ................................................................ 

\ All races, 4-5 years .................................................................. 

White ................................................................................................. 

Black .................................................................................................. 

All races, 6-1 1 years ................................................................ 

White ............... .................................................................................. 

Black .................................................................................................. 

All races, 12-17 years .............................................................. 

White ................................................................................................. 

Black.. ................................................................................................ 

All races, 1844 years .............................................................. 

White ................................................................................................. 

Black.. ................................................................................................ 

See footnotes at end of table. 

20/20 or better I 20/50 or less 

Under $5,000- S’aqPdDO Under $5,000- $10,000 

$5,000 $9,999 and 

OV.3 

$5,000 $9399 over 

- 

Difference in percent 

-3.2 

- 

-1.4 

-3.9 

-2.8 

-3.2 

-2.3 

-3.6 

-4.4 

-2.5 

-1.7 

-1.4 

-2.4 

-4.9 

-2.5 

-10.9 

-1.3 

-0.5 

-4.9 

-6.2 

-5.5 

-11.0 

-2.8 

-1.1 

-2.3 

-1.6 

-1.8 

-0.8 

-1.3 

-1.3 

-1.5 

-1.2 

-1 .I 

-1.4 

-2.6 

-3.0 

-4.3 

-4.5 

-2.6 

-4.6 

-4.3 

-10.8 

-1.8 

0.8 

-2.4 

-210 

0.6 

0.6 

6.8 

0.8 

-0.8 

-0.2 

-Cl,6 

-- 

-0.6 

3.0 

2.8 

0.4 

8.4 

1.6 

-Ok 

-8.4 

-1.0 

0.6 

1.5 

1.8 -1.1 

64 
Table 28. Difkrrnca between maximum and usual visual acuity levels in tha batter eye1 among population age 4.74 years, by annual 

family income, age, race, and sax: United States, 1971.1972-Con. 

I 2W!Cl or better I 20/!50 or less 

Aga, r8ce,g and sax Under 

&%oo 

Difference in parcent 

All races, 45.54 years .............................................................. 

White ................................................................................................. 

Black .................................................................................................. 

All races, 5564 years .............................................................. 

White ................................................................................................. 

Black .................................................................................................. 

411 races,86=14 yrws ........................... .,. ................................. 

Whita ................................................................................................. 

Black .................................................................................................. 

-14.2 -0.2 

-8.5 

-21.7 

-2.3 

-1.6 

-6.5 

-7.2 

-6.1 

-14.6 

-2.6 

. 

-4.4 

-0.1 

. 

-0.2 

-4.8 -0.1 

-4.2 

-6.9 

-6.1 

-23.7 

-3.5 

-3.2 

-8.8 

-2.6 

- 

-2.7 

-1.9 -1.1 

-8.0 

-2.8 

-2.9 

-2.8 

-3.3 

-3.2 

-3.6 

-1.8 

-1.7 

-2.5 

-6.6 

-0.5 

-1.7 -2.8 

-2.0 -2.8 

-0.6 -3.6 

-1.5 -1.5 

-1.S 

-1.7 

-1.3 

-1 A 

-3.9 

-0.5 

-1.1 

-2.6 

-3.1 

-3.3 

-0.5 

-9.3 

-1.2 

-0.8 

-4.3 

-4.3 

-4.3 

-5.2 

-1.2 

-2.7 

. 

-4.6 

-5.2 -2.7 -4.4 

-8.8 -2.3 -13.6 

4.2 0.6 

0.8 

Total, 4.74 wars ................................................................ 

All races, 4-S years .................................................................. 

White ................................................................................................. 

Black .................................................................................................. 

All races, 6-11 years ................................................................ 

white ................................................................................................. 

8iack .................................................................................................. 

All raw, 12.17 years .............................................................. 

White ................................................................................................. 

Black .................................................................................................. 

All ram, 1844 years .............................................................. 

0.8 

2.5 

White ................................................................................................. 

Black .................................................................................................. 

1 a 0.3 

1A 

0.3 

0.3 

4.2 

4.1 

5.8 

1,6 

All rawr,4SS4 yaart . . . . . . . . . . . . . . .,....,.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6 

I---- 

Whita ................................................................................................. 2.7 

Black .................................................................................................. 

All races, 5564 years .............................................................. 

Whita ................................................................................................. 

Black .................................................................................................. 

All races.65.74 years .............................................................. 

Whita .................. . .............................................................................. 

Black .................................................................................................. 

0.2 

- 

1.7 6.2 

1Viwal acuity levels reached with usual correction for those testing to/40 or better and with additional correction on spherical 

refraction or retinoscopy for the remainder. 

2Totalsinclude races other than white and Black. 

66 
Table 29. Percent of population age 4-74 years reaching specified maximum visual acuity leyels in the better eye,1 by region, age, race, and sex, with 

standard errors: United States, 1971-1972 - 

20120 or better 20/25-20140 20/50or less I Age, race,2 and sex 

Both sexes 

I I I I I I I 

Percent of population 

Total, 4-74 years ............... 

All races, 45 years .................. 

White ................................................. 

Black.. ............................................... 

All races, 6-11 years.. .............. 

White ................................................. 

Black ............... /. ................................ 

All races, 12-l 7 years .............. 

White.. ............................................... 

Black ................................................. 

All races, 1844 years.. ............ 

White ................................................. 

Black.. ............................................... 

All races, 45-54 years.. ............ 

White.. ............................................... 

Black ................................................. 

All races, 55-64 years .............. 

White.. ............................................... 

Black.. ............................................... 

73.8 

X 

27.5 

29.5 

3.8 

73.1 

74.6 

- 

36.5 

38.4 

13.5 

73.6 72.9 24.4 

E 

70.1 

68.1 

92.5 

24.1 24.8 25.3 1 .B 1.3 1.6 1.8 

75.9 

48.7 

85.7 

87.0 

75.9 

.87.1 

88.0 

76.2 

78.3 

77.8 

85.4 

50.4 

50.2 

47.9 

32.2 

33.4 

11.7 

70.2 

75.8 

33.3 

82.2 

82.2 

82.7 

87.2 

88.0 

78.0 

74.4 

75.0 

70.3 

63.1 

62.9 

65.2 

33.2 

33.0 

37.2 

42.7 

51.3 

15.5 

79.7 

85.5 

64.8 

87.2 

88.4 

83.6 

86.8 

87.1 

86.0 

66.0 

66.4 

64.4 

55.3 

55.2 

60.1 

29.5 

31.9 

15.8 

15.7 

-_ 

15.91 

14.3: 

70.6, 

-_ 

69.7 

75.0 

83.6 

83.3 

85.7 

27.2 

2.5 

2.3 

3.7 

1.5 

82.0 

-. 

84.1 

68.7 

84.6 

85.0 

79.8 

70.2 

71.7 

47.3 

63.7 

65.0 

41.4 

25.5 

22.7 

50.1 

13.6 

12.1 

24.1 

12.4 

11.5 

22.1 

19.7 

20.2 

11.4 

46.9 

47.1 

47.7 

1.5 

1.2 

0.7 

0.8 

0.5 

0.4 

1.7 

2.0 

2.0 

3.1 

2.6 

2.6 

4.3 

All races, 65-74 years.. ............ 

White.. ............................................... 

Black ................................................. 

Male 

- 

37.4 59.5 

38.7 59.0 

23.3 67.9 

61.8 56.3 

60.6 48.7 

78.5 80.5 

28.2 20.2 

22.4 14.5 

66.2 34.7 

16.1 12.5 

16.0 11.4 

17.3 15.9 

12.3 13.0 

11.4 12.9 

21.5 13.2 

24.5 32.5 

24.1 32.6 

27.6 32.3 

36.9 40.7 

37.1 42.0 

34.8 34.8 

60.4 60.0 

60.6 60.3 

56.3 59.1 

27.9 

24.0 

17.6 

15.5 

30.6 

14.7 

14.3 

18.4 

28.2 

26.6 

52.7 

31.8 

30.4 

55.7 

54.2 

52.7 

70.9 

8.3 

7.7 

20.4 

Total, 4-74 years ............... 74.4 77.6 74.9 77.7 24.1 21.5 23.8 20.5 1.5 

All races, 4-6 years.. ................ 

White.. ............................................... 

Black ................................................. 

All races, 6-l 1 years.. .............. 

White ................................................. 

Black ................................................. 

All races, 12-l 7 years.. ............ 

White ................................................. 

Black ................................................. 

All races, 1844 years.. ............ 

White.. ............................................... 

Black ................................................. 

See footnotes at end of table. 

31.1 35.7 SO.2 20.5 68.9 63.8 48.3 77.9 

32.3 34.8 '57.4 20.6 67.7 64.9 42.6 77.6 

6.5 30.8 19.0 19.5 93.5 65.8 72.5 80.5 

69.9 70.8 85.0 76.3 27.8 27.9 14.9 19.7 2.3 

72.3 75.9 85.3 74.7 25.4 22.7 14.7 21.0 2.4 

47.3 30.8 84.1 85.9 50.4 67.9 15.5 12.3 2.3 

83.3 87.1 88.4 91.9 16.7 12.9 11.3 8.0 

84.7 88.1 88.3 94.2 16.3 11.9 11.3 5.8 

75.3 78.9 88.7 92.0 24.7 21.1 11.3 6.1 

87.2 91 .l 86.0 86.6 12.8 8.4 14.0 13.2 

87.8 92.9 85.5 87.2 12.2 6.6 14.5 12.6 

78.5 72.6 87.7 79.5 21.5 27.4 12.3 17.9 

1.7 

1 .o 

8.0 

1.6 

1.8 

0.5 

1.6 

1.8 

0.5 

0.5 

0.5 

1.0 

0.9 

2.1 

6.4 

6.4 

6.6 

0.9 

0.5 

i:X 

1.3 

1.3 

1.3 

0.5 

0.5 

0.8 

0.8 

2.2 

2.4 

1 .o 

0.5 

0.5 

0.8 

0.7 

'0.6 

*I.9 

1.6 

1.7 

4.6 

4.6 

2.9 

8.3 

8.6 

5.7 

1.8 

1.6 

L 

1.8 

4.0 

4.3 

1 .B 

0.2 

1.9 

0.3 

0.1 

2.6 

1 .o 

4.0 

0.1 

0.5 

0.3 

0.2 

0.5 

0.2 

0.0 

0.8 

1.4 

1 .o 

3.4 

4.0 

2.9 

5.1. 

10.6 

7.8 

25.0 

1.2 

1.6 

8.4 

0.1 

0.4 

0.3 

0.4 

66 
Table 29. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye,l by region, age, race, and sex, with 

standard errors: United States, 1971-1972-Con. 

- 

i 

20120 or better 2012520140 20/60 or less 

North- Mid- North- Mid- North- Mideast west South West east west South West east west South West 

Age, race,2 and sex 

Males-Con. 

All races, 45-54 years.. ............ 

White ................................................. 

Black.. ............................................... 

All races, 5564 years.. ............ 

White ................................................. 

Black.. ............................................... 

All races, 65-74 years.. ............ 

White.. ............................................... 

Black.. ........................... . ................... 

Female, 

Total, 4-74 years ............... 

All races, 4-5 years.. ................ 

White.. ............................................... 

Black.. ............................................... 

All races, 6-11 years.. .............. 

White ................................................. 

Black ................................................. 

All races, 12-l 7 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All races, 1844 years.. ............ 

White ................................................. 

Black.. ............................................... 

All races, 46-54 years.. ............ 

White ................................................. 

Black.. ............................................... 

All races, 55-64 years.. ............ 

White ................................................. 

Black.. ............................................... 

All races, 65-74 years.. ............ 

White ................................................. 

Black.. ............................................... 

Both sexes 

Total, 4-74 years ............... 

All races, 4-5 years.. ................ 

White ................................................. 

Black.. ............................................... 

See footnotes at end of table. 

Percent of population 

83.5 77.9 68.6 74.8 14.2 20.6 30.9 24.6 

83.7 79.5 71.4 77.0 13.9 18.9 28.6 22.3 

79.3 64.9 59.3 43.8 20.7 34.5 36.7 56.2 

51.8 59.0 64.4 70.6 43.2 41 .o 42.2 24.5 

50.9 58.3 54.0 71.7 43.7 41 J 42.3 23.6 

75.3 80.9 57.0 43.8 21.5 19.1 41.0 46.7 

25.0 38.5 27.3 40.7 69.2 55.9 62.8 5i.a 

26.0 39.0 29.2 42.0 68.1 55.5 64.6 49.6 

6.9 28.7 15.4 23.0 87.7 64.5 57.3 72.1 

73.3 71.7 

24.6 37.3 

27.1 42.5 

28 4.9 

77.0 698 

80.3 75.6 

50.2 34.8 

86.7 77.3 

89.8 76.3 

77.0 86.4 

86.9 83.3 

88.3 83.3 

75.0 83.7 

74.3 70.3 

73.3 89.4 

86.6 75.1 

49.4 67.7 

49.8 68.5 

9.7 582 

38.0 29.5 

39.4 28.7 

15.3 42.1 

72.4 

E 

31.3 

68.5 24.7 26.7 25.6 

59.6 68.7 

55.7 59.7 

84.8 87.7 

28.4 26.5 

222 14.3 

652 55.3 

19.4 13.9 

20.0 11.6 

13.6 19.6 

16.1 12.1 

16.2 11.5 

15.3 14.0 

29.2 339 

30.6 35.8 

21.4 24.9 

32.3 39.3 

31.5 41.6 

41.8 29.7 

63.5 58.0 

64.3 57.5 

51.5 60.6 

29.6 

11.6 71.0 88.4 

40.3 iia 68.5 

12.3 10.7 92.1 

88.2 

89.3 

73.4 64.3 22.6 35.4 

85.7 64.5 19.3 

44.2 59.9 49.8 

352 

40.1 

85.9 73.4 9.7 25.5 

88.4 75.4 8.3 

79.5 52.3 23.0 

23.7 

47.7 

87.5 829 12.0 16.0 

88.4 83.1 108 

84.5 79.9 22.4 

159 

18.6 

63.8 66.0 23.9 

62.4 66.8 25.1 

70.1 51.8 6.7 

30.5 

48.2 

56.1 56.5 49.7 37.3 

56.2 .59.8 49.6 

62.7 40.3 84.4 

35.7 

59.7 

31 .l 34.7 51.6 569 

33.6 36.0 51.5 

16.2 23.5 53.5 

55.4 9.1 

70.1 31.2 

2.3 

2.4 

5.0 

0.6 

0.6 

4.9 

1.5 0.4 

1.6 - I-- 0.6 2.0 

3.4 

5.4 3.6 4.8 

3.2 2.0 9.5 

5.8 5.5 9.9 8.3 

5s 

5.4 

2.0 

6.1 8.5 

27.3 4.9 

2.0 1.9 

+ 4.4 3.0 - 

20 

0.4 

1.9 

10.3 

1.8 0.2 0.3 

0.4 

1.6 

1.8 

1 .l 

8:: 

1.8 

1.6 

4.7 

0.9 

0.6 

5.9 

10.4 

2.1 

0.5 

0.3 

3.3 0.3 

3.7 - 

0.9 

08 

0.9 

0.6 0.4 

0.5 0.1 

1.0 1.5 

0.5 2.3 

1 .B 

3.5 4.9 

4.6 

1 .I 

1.1 

1 A 

2.6 

2.7 

2.1 

7.6 

4.2 

4.5 

7.0 11 .o 8.4 

6.7 

6.4 

Standard error 

394 

i 8.43 

67 
Table29. Percent of population age 4-74 wars reachina soecified maximum visual acuitv levels in the better eve.' bv reaion.aae.race.and sex.with 

- 

Age,race,2 and sax 

r 

i 

standard errors: United States, 1971-1972-Con. 

. - - 

20/20or better 20/25-20140 20150 or less 

m Ncstth‘ ( iii 1 South ( West "e$I- ( ir$ 1 South 1 West 

Both sexes-Con. Standard error 

All races, 6-1 I years ................ 

White ................................................. 

Black.. ............................................... 

All races, 12-1 7 years .............. 

White ................................................. 

Black ................................................. 

All races, 1844 years .............. 

White ................................................. 

Black ................................................. 

All races, 45-54 years .............. 

White ................................................. 

Black ................................................. 

All races, 5564 years .............. 

White ................................................. 

Black ................................................. 

All races, 65-74 years .............. 

White ................................................. 

Black ................................................. 

Male' 

- 

4.12 4.20 2.39 

4.38 4.33 3.76 

6.87 14.69 6.80 

5.82 2.92 2.41 

6.32 3.56 2.01 

14.83 6.92 3.70 

3.78 I.28 1.89 

3.85 1.40 2.29 

10.07 4.49 3.16 

1.74 5.72 6.28 

2.04 6.01 8.81 

10.02 4.17 9.36 

6.22 3.26 6.44 

4.93 3.11 7.01 

19.00 11.04 10.54 

4.55 3.95 1.30 

4.66 4.20 084 

4.11 11.04 7.25 

Total, 4-74 years ............... 3.44 

All races, 4-5 years .................. 

White ................................................. 

Black.. ............................................... 

All races, 6-11 years ................ 

White ................................................. 

Black ................................................. 

All races, 12-17 years .............. 

White. ................................................ 

Black ................................................. 

All races, 1844 years .............. 

White ................................................. 

Black ................................................. 

All races. 45-64 years .............. 

8.71 

8.82 

9.47 

5.49 

6.74 

16.16 

6.53 

6.21 

18.03 

5.28 

5.71 

20.53 

3.92 

White. ................................................ 

Black ................................................. 

All races, 5554 years .............. 

White ................................................. 

Black ................................................. 

4.38 

41.05 

3.68 

3.35 

18.52 

See footnotes at end of table. 

3.3'7 0.56 1 1.16 0.09 

3.61 

7.2!5 

3.14 

0.79 1.37 

1.18 0.36 

0.83 1.16 

0.33 

0.31 

3.66 

12.92 

3.66 4.12 

3.71 3.97 

7.32 14.53 

5.17 3.87 

5.45 4.53 

14.83 6.92 

3.55 1.34 

3.62 1.41 

9.90 4.42 

1.88 6.05 

2.15 6.30 

6.97 5.82 

6.90 3.26 

5.74 3.11 

17.35 11.04 

3.05 5.77 

2.76 6.11 

14.81 8.36 

2.32 3.42 

3.76 3.72 

6.78 7.60 

2.33 2.92 

1.92 3.61 

3.74 13.44 

0.97 1.28 0.25 

0.49 

1.03 

-- 

0.95 

8.5S 

1.94 0.92 

2.31 0.79 

3.16 7.72 

6.35 5.65 

8.66 5.99 

8.39 21.10 

5.99 3.62 

6.30 4.66 

12.80 20.36 

2.41 4.81 

2.65 4.98 

5.17 8.78 

0.29 0.33 0.16 

0.28 0.36 

1.82 0.27 

099 0.81 

0.05 

0.69 

5.32 

- 

5.7S 

21.10 

0.60 

1.20 0.90 

3.32 1.91 

1.25 - 

0.94 

1.56 

2.21 

2.42 

1.31 

0.30 

0.33 

0.75 

0.15 

0.17 

1.60 

0.96 

1.01 

2.90 

-- 

3.63 

20.56 

2.33 

1.54 - 2.68 

2.65 - 3.19 

3.39 

-- 

3.11 

6.75 

2.03 2.85 2.88 

2.42 3.02 2.38 

12.87 3.19 6.49 

1.94 

2.02 

2.42 

3.94 

4.32 

1.40 

2.00 

-- -- 

4.61 

3.69 2.66 1.85 I.86 0.61 0.60 0.25 0.46 

8.71 9.94 9.17 5.26 - 0.33 1.60 

5.09 8.82 

7.27 9.47 

10.04 

l 21.32 

3.88 

12.73 5.87 

14.04 727 

- 0.31 

- l 8.24 

1.73 

1.96 

5.94 

-- 

6.54 

2.19 

4.62 3.07 1.23 1.25 

9.08 

0.13 

5.56 

16.37 !% 

4.82 6.61 

4.23 3.04 

1.65 1.47 

2.20 1.02 

2.30 

-_ 

1.36 

5.24 

6.53 1.05 2.18 2.21 

3.76 

4.20 

2.22 

0.14 

6.21 2.25 2.71 1.36 

18.03 12.36 1.30 5.48 

1.07 5.28 089 2.22 1.04 

0.95 5.71 1.22 3.17 0.88 

21.47 20.53 9.11 6.31 16.75 

4.17 

-. 

3.60 

30.05 

5.59 7.70 8.15 4.23 

5.78 7.32 11.77 3.60 

41.05 14.49 9.54 30.05 

1.61 

0.08 

0.14 

4.72 

0.65 

0.67 

2.05 

7.40 

-. 

6.69 

30.85 

6.17 6.02 6.36 4.44 3.24 

4.46 6.28 6.66 4.20 

18.27 16.59 12.32 24.15 

4.71 - 

2.16 I - 

3.65 

2.38 

2.38 1.92 

9.87 10.60 

10.10 12.73 

'23.31 12.07 

4.37 3.10 

4.91 4.82 

10.06 4.08 

1.05 2.01 

2.25 2.50 

12.36 1.30 

1.25 2122 

1.64 3.17 

9.11 6.31 

6.76 7.94 

6.28 11.77 

13.22 9.90 

6.02 7.40 

6.28 7.46 

34.69 13.88 

68 
Table 29. Percent of population age 4-74 years reaching specified maximum visual acuity levels in the better eye, 1 by region, age, race, and sax, with 

standard errors: United States, 1971-1972-Con. 

20/20 or better I 2012520140 I 20/50 or less 

Age, race,* and sax North- Mideast west South west North- Mid- South west North- Mideast west east west South West 

Male-Con. Standard error 

All races, 65-74 years.. ............ 

White.. ............................................... 

Black.. ............ . .................................. 

Female 

3.89 3.38 

4.03 3.72 

8.83 11.49 

3.70 4.55 2.88 1 5.88 1 394 4.73 1 2.36 1 3.56 ( 3.38 3.00 

2.98 4.95 

5.80 8.20 

592 3.46 

11.92 8.93 

Total, 4-74 years.. ................... 3.14 2.18 

All races, 4-5 years.. ................ 10.16 12.42 

White.. ............................................... 11.10 12.64 

Black.. ............................................... 6.32 9.17 

All races, 6-l 1 years.. .............. 5.33 5.06 

White ................................................. 5.15 4.62 

Black.. ............................................... 7.49 19.42 

All races, 12-l 7 years.. ............ 6.42 5.48 

White.. ............................................... 7.42 6.23 

Black ................................................. 11.62 4.82 

All races, 1844 years.. ............ 3.33 2.48 

White ................................................. 3.14 2.66 

Black.. ............................................... 7.19 2.38 

All races, 45-54 years.. ............ 3.66 6.92 

White ................................................. 4.25 8.50 

Black.. ............................................... 7.25 9.97 

All races, 5564 years.. ............ 9.08 7.17 

White.. ............................................... 8.67 7.62 

Black.. ............................................... 4.42 24.13 

All races, 65-74 years.. ............ 5.65 5.55 

White.. ............................................... 5.88 5.58 

Black ................................................. 6.90 19.99 

2.81 2.59 

- - 

10.49 3.73 

2.71 2.48 2.90 

9.75 13.39 10.49 

16.44 4.45 

9.02 2.68 

1.92 2.47 

5.51 2.17 

10.04 19.16 

5.11 5.59 

4.82 6.23 

7.38 14.54 

2.11 1.61 

2.01 1.75 

3.48 7.26 

5.54 8.44 

7.34 9.08 

12.14 16.29 

6.50 5.10 

7.94 5.99 

12.66 23.68 

0.87 

2.32 

9.93 

2.50 

2.05 

12.73 

10.47 12.63 16.44 

4.53 24.80 9.02 

5.54 5.08 1.91 

5.37 4.15 5.51 

7.49 19.42 9.91 

4.76 7.25 4.96 

5.39 8.06 4.82 

11.62 4.82 7.41 

2.95 2.48 2.28 

2.69 2.63 2.04 

6.88 2.26 4.31 

4.09 6.99 5.70 

4.63 8.50 7.33 

4.81 11.56 10.09 

8.33 7.17 6.70 

8.02 7.62 7.53 

2.26 24.13 17.74 

4.51 6.63 3.75 

4.13 6.86 4.77 

18.21 17.77 9.38 

4.45 3.56 2.16 - 

2.68 3.05 21.61 - 

2.31 0.40 1.34 0.14 

1.96 0.45 1.51 - 

19.16 - - 0.57 

5.22 1.95 2.06 0.29 

5.85 2.24 2.22 - 

14.54 - - 0.89 

1 A0 0.58 0.54 0.30 

1.53 0.58 0.58 0.09 

7.59 2.72 0.55 1.23 

9.05 1.34 0.37 1.08 

3.38 

5.03 

0.61 

- 

0.31 

0.33 

0.54 

0.59 

0.29 

0.30 

2.36 

1.52 

1.60 

2.27 

2.52 

4.82 

5.24 

5.77 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spherical refraction or 

retinoscopy for the remainder. 

‘Totals include races other than white and Black. 

69 
Table 30. Difference between maximum1 and usual visual acuity levels in the better eye among population age 4-74 years, by region, 

age, race, and sex: United States, 1971-1972 

20120 or better I 20/50 or less 

Age, race,2 and sex 

]-q-q-G 

1 .o k Both sexes Difference in percent Total, 4-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.7 1.1 1.2 

All races, 4-5 years ............................................................ 

White ........................................................................................... 

Black.. ......................................................................................... 

0.6 1.7 

2.2 

0.4 

0.7 

-5.4 : 

-3.4 -1.8; -2.8 

-2.2 -2.9 

-0.6 

t 

-1.0 

-1.2, -2.0 

All races, 6-11 years.. ........................................................ 

White ........................................................................................... 

Black.. ......................................................................................... 

All races, 12-l 7 years ........................................................ 1.6 

0.7 

0.5 

0.9 

White ........................................................................................... 1.2 0.8 0.3 

Black.. ......................................................................................... 4.8 2.4 1.8 

-0.5 

1.1 -0.2 -3.6 

-3.4 -2.5 

1.6 -2.6 -2.0 

1.8 -2.2 

-5.8 

All races, 1844 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5 0.9 0.5 -0.6 

-1.9 -0.6 -1.6 

-3.1 -3.2 - 

-0.5 -1.2 -1.6 

1.7 

1.9 

2.8 

3.8 

2.5 

2.1 

1.3 

1.7 

0.8 

7.6 

0.8 1.2 

0.7 

0.9 

1.3 

2.5 

White.. ......................................................................................... 

Black.. ......................................................................................... 

1.7 1.4 

-0.6 

-0.9 

-0.9 

-0.9 

3.6 2.7 -2.1 

1.6 0.8 -1.7 

1.6 2.9 -4.1 

1.5 

1.5 

0.7 

0.9 -4.7 

0.8 -4.7 

0.6 -4.6 

-0.6 1.1 -1.7 

-1.3 -1.5 -2.8 

-1 .o -2.5 -3.3 

-0.9 -1.9 -2.2 

- -3.4 -17.1 

-1.4 -2.7 -2.3 

-1.3 -1.8 -1.6 

-2.5 -3.8 -4.1 

-1.8 -9.0 -5.3 

-2.4 -8.7 -4.6 

-3.1 -13.9 -10.4 

All races, 45-54 years.. ...................................................... 

White.. ......................................................................................... 

Black.. ......................................................................................... 

2.1 

2.0 

0.4 

1.4 

All races, 5564 years.. ...................................................... 

White ........................................................................................... 

Black.. ......................................................................................... 

All races, 65-74 years.. ...................................................... 

White.. ......................................................................................... 

Black.. ......................................................................................... 

Male 

All races, 45 years.. .......................................................... 

White ........................................................................................... 

Black.. ......................................................................................... 

All races, 6-l 1 years.. ........................................................ 1.4 1.5 -0.6 :I 4.0 -1.1 1 -2.5 

White ........................................................................................... 

Black.. ......................................................................................... 

All races, 12-17 years.. ...................................................... 

White.. ......................................................................................... 

Black.. ......................................................................................... 

See footnotes at end of table. 

-3.9 -1.5 -2.9 -ll- -4.9 - - 

-1.2 -0.9 -2.9 

0.7 

1.2 

1.5 

0.9 

0.5 

1.7 

1.5 

-0.3 

-2.3 

-3.5 

1.4 

2.3 

1.6 -2.5 -1.4 

-9.1 -I I 

-0.6 -1 .s 

-2.3 - 
Table 30. Difference between maximum1 and usual visual acuity levels in the better eye among population age 4-74 years, by region, 

age, race, and sex: United States, 1971-197%Con. 

Age, race,2 and sex 

20120 or better 20150 or less 

North- Mid- wast South West North- Mideast east west South West 

Male-Con. Difference in percent 

I - 

0.7 1.3 0.8 -0.7 -0.8 -0.5 -2.4 

-0.6 -2.4 

-2.1 

-4.4 -3.5 

-3.5 -1.4 

-6.4 -30.3 

-1.9 -1 .o 

-0.8 -0.5 

-6.4 - 

-10.1 -6.5 

-8.6 -4.7 

-16.1 -19.7 

All races, 1844 years.. ...................................................... 

White ........................................................................................... 

Black ........................................................................................... 

All races, 45-54 years.. ...................................................... 

White ........................................................................................... 

Black ........................................................................................... 

All races, 5564 years.. ...................................................... 

White ........................................................................................... 

Black ........................................................................................... 

All races, 65-74 years.. ...................................................... 

White.. ......................................................................................... 

Black ........................................................................................... 

Female 

All races, 4-5 years.. .......................................................... 

White ........................................................................................... 

Black ........................................................................................... 

All races, 6-11 years.. ........................................................ 

1.3 

0.7 

1.7 2.0 

4.0 

-0.7 

-0.7 

-0.5 

-0.7 

-1.7 

-6.2 

4.3 

2.4 

2.7 

3.5 

1.8 

0.9 

1.8 

Black.. ......................................................................................... 

All races, 12-17 years ........................................................ 

White.. ......................................................................................... 

Black.. ........................................................................ .:. .............. 

All races, 1844 years ........................................................ 

1.6 

1.7 

White.. ......................................................................................... 

Black ........................................................................................... 

All races, 45-54 years.. ....................................................... 

White ........................................................................................... 

Black.. ......................................................................................... 

0.2 

0.4 

4.0 

3.3 

All races, 5564 years.. ...................................................... 4.6 

White.. ......................................................................................... 1.9 

Black ........................................................................................... 2.7 

3.8 

0.9 2.8 

1.4 

-0.3 

-4.5 

-0.1 

-2.3 

2.3 0.3 

0.3 1.1 

1.7 

-3.9 -2.3 

-7.4 -2.1 

-6.1 

0.7 -8.4 

1 .o 2.2 0.3 -0.5 

1.1 

0.5 

3.1 0.4 

-4.6 

0.6 0.8 1.6 -1.5 -2.7 

0.2 

4.7 

0.4 

0.5 

1.4 

1.8 

0.6 0.3 

-1.8 

-0.4 

-2.3 

-6.1 

0.6 0.8 

1.1 

3.7 

0.8 

1.2 

3.9 

-1.8 

-0.4 

-0.9 

-1.2 

-1.5 

-0.5 

0.1 2.4 

1.8 1.3 -0.1 

4.2 -9.7 -3.6 

-2.8 -2.3 

-1.8 -5.9 

See footnotes at end of table. 

71 
Table 30. Difference between maximum1 and usuel visual acuity levels in the better eye among population age 4-74 years, by region, 

MS, rata, end sex: Unilted States, 1971.1972-Con. 

I’ 20/20 or better I 20/50 or less 

Age, race,2 and sex North- Mid* West South West Northeast east 

I ” 

Femele-Con. 

All reces, 65~74 yasrr .,,.......,..,.....,.............,.,.........,.~........ 

White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Black ,,..,,,,.,.,,.,.,........,..,... .**.... .,.., . ..* ,,..... ..*..*.* .,......,. . . . . . ..*.**... ,... 

lVisual acuity levels reached with usual correction for tholle tuting 20/40 or better snd with additional correction on spherical 

refraction or rstinosoopy for the remainder. 

2Totals include races other than white and Black. 

72 
Table 31. Percent of population age 4-74 years reaching specified visual acuity levels for maximum distance vision in the better eye,l by size of place of 

residence, age, race, and sex, with standard errors: United Stetes, 1971-1972 

Age, race,2 and sex 

Both sexes ’ 

20/20 or better 20150 or less 

Non- NonUrban urban- Rural Urban urben- Rural 

ized ized 

Percent of population 

Total, 4-74 years ............... 73.4 74.3 74.1 1.9 1.5 1.3 1.73 158 1.09 0.28 0.45 0.28 

All races, 4-5 years.. ................ 

White ................................................. 

Black.. ............................................... 

All races, 6-11 years.. .............. 

White ................................................. 

Black.. ............................................... 

All reces, 12-l 7 years.. ............ 

White.. ................................................ 

Black.. ............................................... 

All races, 18-44 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All races, 4554 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All reces, 5564 years.. ............ 

White ................................................. 

Black.. ............................................... 

All races, 65-74 years.. ............ 

White ................................................. 

Black.. ............................................... 

Male 

- 

35.4 

39.4 

14.0 

3.5 4.49 

4.90 

3.66 

72.2 

76.8 

51.5 

83.4 

84.6 

78.5 

85.8 

86.7 

80.8 

72.6 

72.6 

72.1 

55.9 

56.4 

54.7 

33.3 

34.4 

23.9 

28.5 

30.1 

21.3 

74.2 

75.9 

61.8 

86.1 

66.1 

79.0 

87.1 

88.0 

77.6 

73.0 

72.7 

75.6 

59.8 

59.6 

64.8 

35.2 

37.0 

14.5 

26.8 

28.7 

6.1 

74.8 

75.7 

65.4 

84.2 

84.7 

79.5 

87.3 

87.3 

86.3 

72.3 

74.3 

48.5 

60.0 

60.3 

52.7 

31.2 

32.5 

12.9 

2.1 

1.9 

3.4 

1.2 

1.3 

0.9 

0.7 

0.8 

0.3 

0.7 

0.6 

1.3 

1.9 

1.9 

2.6 

2.5 

2.3 

3.9 

10.9 

9.8 

19.9 

1.7 

11.5 

1 .o 

1.0 

0.9 

0.5 

0.5 

1.7 

1.9 

2.40 

1.70 

12.52 

1.11 

1.37 

0.95 

0.53 

0.59 

0.9 

0.9 

1.7 

1.6 

1.7 

0.36 

0.38 

1.78 

1.41 

1.56 

0.6 

0.3 

6.8 

6.9 

6.4 

12.9 

1 .o 

1 .o 

0.7 

0.1 

0.0 

0.3 

0.9 

0.6 

3.9 

4.2 

3.6 

2.0 

5.3 

4.6 

13.9 

4.11 13.17 

4.29 16.46 

4.05 15.14 

2.33 4.62 

2.30 5.19 

6.41 13.80 

2.44 2.92 

2.39 3.30 

5.88 12.62 

1.56 1.45 

1 .a0 1.72 

2.89 11.37 

3.91 5.04 

4.31 7.06 

4.33 22.18 

3.11 5.72 

3.02 6.19 

11.14 23.78 

2.74 3.97 

2.92 4.39 

5.04 12.92 

2.77 

3.31 

7.28 

2.30 

2.69 

11.34 

1.35 

1.21 

4.85 

4.87 

5.09 

11.38 

5.18 

5.76 

12.15 

3.19 

2.88 

6.16 

0.98 

1.13 

2.42 

0.56 

0.72 

0.44 

0.38 

0.45 

0.26 

0.18 

0.20 

0.70 

0.63 

0.76 

1.14 

0.75 

0.98 

2.13 

1.95 

1.89 

6.17 

0.46 

0.40 

5.23 

2.86 

3.11 

8.86 

1.60 

1.80 

_ 

0.63 

0.68 

0.71 

0.06 

0.04 

0.31 

0.52 

0.69 

1.97 

1.79 

1 .a5 

2.25 

1.97 

1.75 

6.34 

Total, 4-74 yeers ............... 77.1 74.9 75.2 1.3 1.5 1.3 1.74 3.57 1.49 0.39 0.63 0.39 

E 

All reces, 45 years.. ................ 

White ................................................. 

Black.. ............................................... 

All races, 6-11 years.. .............. 

White ................................................. 

Black.. ............................................... 

All races, 12-l 7 years.. ............ 

White ................................................. 

Black.. ............................................... 

All reces. 1844 years.. ............ 

White ................................................. 

Black.. ............................................... 

All reces, 4554 years.. ............ 

White ................................................. 

Black ................................................. 

44.9 28.6 28.5 6.7 5.01 12.39 8.55 

47.2 27.4 30.2 

20.5 33.2 8.6 

5.51 15.22 9.56 

9.19 25.79 5.86 

75.3 77.5 75.4 4.04 

77.6 78.1 74.9 

64.8 69.5 76.7 

0.3 

0.2 

1.1 

1.6 

1.6 

1.4 

0.1 

3.4 

19.9 

1.7 

1.7 

1.9 

2.6 

2.9 

3.84 5.90 

4.01 692 4.66 

6.62 16.26 5.92 

2.25 5.44 2.19 

0.21 

0.19 

1.12 

0.74 

1 .oo 

0.85 

0.08 

4.23 

3.33 

19.42 

1.72 

2.07 

2.30 

2.85 

3.26 

86.8 87.6 89.4 

88.6 91.0 89.0 

81.5 ‘79.9 91.6 

88.1 87.3 87.5 

0.5 

0.3 

0.3 

l m 

0.4 

1.97 5.16 2.64 

7.40 l 35.49 4.87 

0.24 

0.28 

l - 

2.13 3.07 1.99 

89.5 87.9 87.2 

78.5 *al.4 89.3 

76.7 73.4 77.6 2.3 

0.1 

“3.6 

0.2 

0.2 

0.3 

3.5 

2.63 3.89 2.07 

4.88 28.95 4.66 

0.50 

0.21 

0.24 

0.29 

0.14 

5.25 

4.05 10.17 5.70 1.24 0.27 

77.8 74.0 81.4 2.5 

68.3 ‘69.7 38.4 0.3 l - 

3.76 14.92 5.10 1.39 

10.79 ‘27.01 11.80 0.45 +- 5.08 

See footnotes at end of table. 

73 
Table 31. Percent of population age 4-74 years reaching specified visual zicuity levels for maximum distance vision in the better eye,l by size of place of 

residence, age, race, and sex, with standard errors: United States. 1971-1972-Con. 

20/20 or better 20/50 or less 

Non- NonUrban urban- Rural Urban urban- Rural 

ized bed 

Percent of population 

Age, race,’ and sex 

Male-Con. 

All races, 5564 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All races, 65-74 years .............. 

White.. ............................................... 

Black.. ............................................... 

Female 

Total, 4-74 years ............... 

All races, 4-5 years.. ................ 

White.. ............................................... 

Black.. ............................................... 

All races, 6-1 1 years ................ 

White.. ............................................... 

Black.. ............................................... 

All races, 12-I 7 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All races, 1844 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All races, 45-54 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All races, 5564 years.. ............ 

White.. ............................................... 

Black.. ............................................... 

All races, 65-74 years.. ............ 

White ................................................. 

Black.. ............................................... 

Standard error 

61 .2 57.1 55.4 1 .B 0.5 6.0 3.32 8.84 a.37 1.56 0.77 3.39 

-- 

60.7 56.7 56.3 1.9 6.2 3.81 9.30 8.68 1.71 3.61 

74.5 “65.3 42.5 1.6 l 14.3 3.0 10.96 l 38.18 lg.08 1.22 l 13.96 3.55 

32.3 33.1 32.1 a.4 14.4 3.5 3.44 3.47 4.10 2.37 5.87 1.36 

-- 

33.5 35.4 33.2 7.4 13.6 2.8 3.44 5.29 3.98 2.21 6.74 1.09 

19.8 17.2 11.8 16.9 20.0 13.5 6.90 17.39 6.29 9.01 il.83 7.72 

70.0 73.7 73.0 2.4 1.4 1.3 1.90 I .a0 1.56 0.39 0.56 0.35 

-- -- 

26.2 28.4 25.0 3.9 5.13 17.72 a.51 1.97 

-- 

30.7 32.9 27.0 3.7 6.82 20.75 9.25 2.36 

11 .o 5.2 3.3 4.4 6.29 5.20 3.37 3.36 

69.3 69.7 74.2 0.9 0.8 2.13 a.99 3.20 0.58 0.99 

-- 

76.0 72.7 76.6 1 .o 0.9 2.57 10.95 4.11 0.72 1.11 

39.2 54.6 53.0 0.3 7.01 20.80 9.61 0.40 

79.3 84.9 79.4 1.4 0.9 1.7 4.15 4.95 4.00 0.83 0.96 1.17 

-- 

79.8 85.7 80.6 1 .B 1 .o I .a 4.40 5.66 4.40 1 .oo 1.10 i .28 

75.1 78.5 70.4 - 1.3 6.82 12.00 ia.la 1.35 

83.7 86.8 87.1 1 .o 1.4 0.1 i .a2 2.97 1.33 0.34 0.63 0.11 

-- 

83.9 88.1 87.4 0.8 1.5 0.1 1.92 3.33 1.36 0.37 0.71 0.07 

82.1 74.2 82.7 2.1 0.6 2.80 6.97 a.11 1.12 0.62 

69.1 72.4 67.2 1.7 3.5 1 A 4.82 6.38 6.10 0.76 3.12 0.97 

-- 

68.2 71.2 67.7 1.3 3.7 1.2 6.06 6.84 6.73 0.88 3.30 1.36 

74.9 94.0 60.5 4.1 4.4 5.50 25.62 17.21 1.76 4.57 

51 .a 62.6 64.6 3.0 0.7 2.4 4.26 12.52 4.77 1.10 0.98 1.72 

-- 

52.9 62.5 64.3 2.7 0.7 1 .o 4.45 12.96 5.43 1.40 1.07 

43.4 64.2 73.5 5.2 13.98 33.13 18.52 3.33 

34.0 36.4 30.5 12.7 2.5 6.8 3.06 5.55 3.22 1.87 1.50 

-- 

35 .o 37.9 32.0 11.6 2.5 6.2 3.50 5.63 3.39 1.94 1.62 

26.6 10.4 13.6 22.0 2.6 14.2 5.07 14.34 i 5.89 6.00 3.40 

-- 

1.19 

3.70 

3.77 

6.07 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spherical refraction or 

retinoscopy for the remainder. 

‘Totals include races other than white and Black. 

74 
Table 32. Percent and number of population age 4-74 years reaching at least 20/20 and percent reaching no better than 20/50 maximum 

visual acuity in the better eye,l by ancestry and race, with standard errors: United States, 1971-1972 

Maximum monocular acuity in better eye All 

and ancestry races 

20120 or better 

Spanish, Mexican’ ..................................................... 66.0 65.9 

Chinese, Japanese ...................................................... l 51 .o *43.2 

American Indian3.. .................................................... 71.5 70.3 

All other .................................................................... 74.3 75.4 

20150 or poorer 

Spanish, Mexican’..................................................... “3.4 

Chinese, Japanese ...................................................... *0.2 

American Indian3.. .................................................... *4.2 

All other .................................................................... 1.5 

Total, in population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Spanish, Mexican* ..................................................... 

Chinese, Japanese ...................................................... 

American Indian3 ...................................................... 

All other.. .................................................................. 

White Black Other 

Percent of population Standard error 

l 3.4 

l 2.8 

1.4 

66.7 

2.3 

+78.6 2.93 2.94 

l 54.1 l 15.57 l 37.20 

*83.0 5.21 5.55 

96.5 1.09 1.16 

‘0.3 

l 17.0 

l 0.3 

l 1 .54 

l 0.52 

l 2.86 

0.19 

1.55 

*2.61 

0.22 

Number in thousands 

21,119 1,325 

190 . . . 

548 . . . 

268 . . . 

409 . . . 

. . . 

E 

. . . 

. . . 

. . . 

. . . 

. . . 

1.55 

0.50 

l 19.01 

l 13.91 

l 18.50 

2.25 

l 0.90 

18.50 

‘0.37 

....

....

I ... ..

ksual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spherical 

refraction or retinoscopy for the remainder. 

*Includes Puerto Rican immigrants. 

‘Living off reservations. 

75 
Table 33. Percent of population age 4-74 years with maximum1 visual acuity of 20/20 or better and 20/50 or less1 with manifest 

strabismus, phoria, or no eye muscle imbalance, by age, sex, and race with standard errors: United States, 1971-1972 

Total with 

eye muscle Manifest 

strabismus Phoria No eye muscle 

imbalance imbalance 

- 

20/20 20150 20120 20150 20/20 20150 20120 20150 

or or or or or or or 

better less better less better less better IZS 

Age, sex, and race* 

Both sexes Percent of population 

All races, 4-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79.6 1.5 62.0 72.8 1.6 

White .................................................................................... 

Black .................................................................................... 

70.9 

68.0 

1 .I 

2.9 

1 .o 

61.7 

58.4 

3.7 

4.8 

73.4 

68.4 

0.6 

2.6 

75.6 

66.4 

1.6 

2.1 

All races, 4-l 1 years.. ................................................. 67.1 2.5 71.2 0.6 63.1 

White .................................................................................... 69.5 

Black .................................................................................... 47.3 

All races, 12-24 years.. ............................................... 

White .................................................................................... 

Black .................................................................................... 

All races, 25-54 years.. ............................................... 

White.. ..................................................... . ............................ 

Black .................................................................................... 

84.5 

0.5 

4.5 

1 .o 

51 .I 

49.5 

43.4 

70.8 

69.2 

77.9 

64.5 

64.9 

60.6 

57.4 

58.2 

30.1 

2.8 

4.8 

65.8 

46.9 

1.6 

0.9 

4.8 87.2 0.8 

85.3 

81.3 

0.9 

1.5 

0.9 

5.8 88.8 

80.2 

0.1 

1.8 

87.5 

83.2 

75.8 78.0 82.7 

758.8 

74.3 

0.6 

1.4 

All races, 55-74 years.. ............................................... 

White .................................................................................... 

Black .................................................................................... 

Male 

47.3 

1 .o 

0.5 

3.3 

48.2 2.0 

30.1 13.0 

3.3 

17.2 

78.3 

75.1 

46.0 

47.6 

27.8 

0.6 

0.3 

2.9 

1.5 

12.5 

83.5 

75.0 

47.7 

48.4 

41.4 

All races, 4-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.5 0.8 72.0 1.9 

1.4 

5.0 

75.4 0.6 76.5 

5.4 

9.2 

1.5 

White .................................................................................... 

Black .................................................................................... 

74.6 

73.2 

All races, 4-1 1 years.. ................................................. 69.7 

0.4 

3.5 

1 .o 

71.3 

72.9 

75.8 

72.3 

0.2 

3.4 

1.2 

77.4 

69.3 

55.3 73.7 65.9 

1.5 

1.4 

1.9 

White .................................................................................... 70.5 

Black .................................................................................... 63.2 8.9 

51.3 

58.0 

1.6 

75.0 

64.7 

66.8 2.1 

58.9 0.8 

All races, 12-24 years.. ............................................... 92..7 0.3 79.4 95.7 

9.3 

88.1 

White .................................................................................... 

Black .................................................................................... 

92.4 

95.3 

80.8 

0.3 

0.4 

74.9 

97.2 

2.0 96.0 

95.3 

All races, 25-54 years.. ............................................... 86.5 0.6 80.3 0.3 

88.8 

86.3 

84.1 

0.2 

0.2 

0.2 

0.5 

White .................................................................................... 81.8 

Black .................................................................................... 72.6 

0.4 

0.3 

2.0 

88.4 

77.7 

0.8 81.7 

69.4 

85.6 

69.3 

All races, 55-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

White .................................................................................... 

Black .................................................................................... 

46.7 

-- 

47.6 

34.5 

63.6 4.2 44.6 

0.3 

0.3 

1.3 48.6 

0.5 

0.9 

5.7 

1 .o 66.5 2.3 45.6 0.5 49.1 5.6 

17.4 41 .I 18.5 24.3 19.4 44.9 7.2 

See footnotes at end of table. 

76 
Table 33. Percent of population age 4-74 years with maximum visual acuity of 20/20 or better and 20/50 or less1 with manifest 

strabismus, phoria, or no eye muscle imbalance, by age, sex, and race with standard errors: United States, 1971-1972-Con. 

Age, sex, and race* 

Female 

All racas, 4-74 years . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67.6 2.0 

White .................................................................................... 

Black .................................................................................... 

All races, 4-11 years ................................................... 

White .................................................................................... 

Black .................................................................................... 

All races, 12-24 years ................................................. 

White .................................................................................... 

Black .................................................................................... 

All races, 25-54 years.. ............................................... 

White .................................................................................... 

Black .................................................................................... 

All racas, 55-74 years ................................................. 

White .................................................................................... 

Black .................................................................................... 

Both sexes 

All races, 4-74 years.. ............................................ 

White .................................................................................... 

Black .................................................................................... 

All races, 4-11 years ................................................... 

White .................................................................................... 

Black .................................................................................... 

All races, 12-24 years ................................................. 

White .................................................................................... 

Black .................................................................................... 

All races, 25-54 years ................................................. 

White .................................................................................... 

Black .................................................................................... 

All races, 55-74 years ................................................. 

White .................................................................................... 

Black .................................................................................... 

Total with 

eye muscle Manifest 

strabismus Phoria No eye muscle 

imbalance imbalance 

20120 20150 20120 20150 20120 20150 20120 20150 

or or or or or or or 

better less better less beZer less better less 

68.0 1.7 

63.9 2.4 

64.4 1.0 

68.4 1.1 

30.5 - 

79.0. 1.5 

80.2 1.3 

73.6 2.4 

71.8 1.4 

71.1 1.5 

76.0 0.8 

47.7 4.3 

48.7 2.9 

26.9 9.8 

1.96 0.43 

2.15 0.40 

3.40 0.98 

4.01 0.61 

3.79 0.39 

10.64 4.93 

2.10 0.55 

2.21 0.59 

6.79 1.51 

2.50 0.47 

2.92 0.53 

6.60 0.38 

4.97 1.24 

4.80 0.80 

9.21 3.13 

55.7 5.1 71.4 0.9 73.8 1.7 

43.2 4.7 65.6 2.1 63.9 2.7 

47.0 5.0 68.6 

73.6 - 

32.5 - 

81.3 0.7 

65.5 8.2 83.6 0.2 

62.3 - 72.2 2.7 

54.7 3.9 76.1 0.7 

55.7 3.9 75.4 0.8 

39.8 4.6 80.2 0.3 

52.2 4.6 

Percent of population 

55.5 1 4.9 1 70.5 1 1.3 1 72.6 1 1.8 

I 

50.8 4.1 

15.8 15.5 

47.1 

49.1 

29.7 

60.1 1 .o -I- 64.8 1 .o 

36.3 1 .o 

85.4 1.3 

-t 

86.1 1.3 

80.0 1.7 

81.3 0.8 -I-- 81.5 0.7 

79.3 1.9 

46.9 5.7 --I-- 47.8 5.2 

38.6 10.8 

Standard error 

3.55 1.23 1.86 0.38 1.09 0.24 

3.93 1.42 2.09 0.23 1.17 0.26 

8.52 1.44 3.48 1.18 1.65 0.49 

11.40 1.59 4.17 0.60 2.07 0.59 

13.71 1.75 4.03 - 2.24 0.70 

26.80 - 11.00 5.33 4.55 0.42 

7.40 2.66 2.10 0.34 1.16 0.21 

9.55 3.17 2.05 0.12 1.37 0.22 

15.38 - 7.41 1.74 2.51 0.62 

6.39 2.06 2.39 0.39 1.22 0.20 

7.31 2.29 2.64 0.44 1.27 0.23 

12.29 1.55 7.54 0.22 3.12 0.43 

-- 

Sea footnotes at end of table. 

77 
Table 33. Percent of population age 4-74 years with maximurn visual acuity of 20/20 or better and 20150 or less1 with manifest 

strabismus, phoria, or no eye muscle imbalance, by age, sex, and race with standard errors: United States, 1971-1972-Con. 

Ma% Standard error 

Age, sex, and race* 

All races, 4-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.38 0.25 

- 

2.36 1 0.32 1 1.36 \ 0.27 

I I I 

White .................................................................................... 

Black .................................................................................... 

All races, 4-1 1 years.. ................................................. 

White.. .................................................................................. 

Slack .................................................................................... 

All races, 12-24 years.. ............................................... 1.24 1 -1 I.351 0.21 

White .................................................................................... 

Black .................................................................................... 

1.41 - 1.48 0.25 

3.28 - 4.30 0.25 

All races, 25-54 years.. ............................................... 2.49 0.31 1.57 0.28 

White .................................................................................... 

Black .................................................................................... 

All races, 55-74 years.. ............................................... 

White . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Black . ..I......................................................... . . . . . . . . . . . . . . . . . . . . . . . 

Female 

2.51 0.22 5.06 0.61 

5.38 1.92 9.12 2.93 

5.88 1.02 14.20 

- 

6.16 - 17.56 

17.57 10.67 31.89 

3.01 0.30 12.01 2.05 

3.61 0.36 15.06 2.52 

3.09 - 23.00 

2.38 0.28 6.37 0.89 

- 

3..21 0.32 6.95 1.27 

13.,63 0.28 16.47 

5.28 0.61 9.93 1.28 

- 

5.27 0.48 10.53 1.25 

12.06 6.75 24.13 9.35 

5.99 1 0.73 1 2.68 1 0.99 

6.10 0.38 2.94 1.10 

9.48 10.43 7.58 2.54 

2.17 0.48 1.23 0.33 

White.. .................................................................................. 

Black .................................................................................... 

White.. .................................................................................. 

Black .................................................................................... 

All races, 4-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.41 0.63 4.91 1.87 

- 

2.68 0.62 5.26 2.07 

4.161 1.15 12.59 3.75 

All races, 4-11 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.88 0.68 19.58 3.33 

- 

5.131 0.78 21.12 3.60 

8.06 - 32.37 

All races, 12-24 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.75 0.90 7.93 4.68 

- 

2.:37 0.95 9.85 5.41 

lo.:23 2.33 28.93 

All races, 25-54 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.42 0.78 8.54 2.97 

3.87 0.88 9.40 3.19 

3.97 0.52 14.56 4.39 

All races, 55-74 years .,,......................,....................... 7 116 1.80 8.53 2.69 

- 

6.71 1.34 11.26 3.11 

1 I.116 4.98 9.50 11.37 

- 

3.29 1 0.57 1 1.81 1 0.51 

White.. .................................................................................. 

Black .................................................................................... 

White.. .................................................................................. 

Black .................................................................................... 

3.89 0.68 1.48 0.36 

4.13 0.30 3.20 0.58 

8.47 2.07 2.24 1.07 

White.. .................................................................................. 

Black .................................................................................... 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spherical 

refraction or retinoscopy for the remainder. 

‘Totals include races other than white and Black. 

78 
Table 34. Prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age lenses first worn, 

among population 6-74 ars, by aie, race, and sex: United States, 1971-1974 

II 

Race, sex, and selected medical 

history items 

All Age in years 

ages. 

6-74 

wars 6-11 ._ l 12-17 18-24 25-34 3544 45-54 55-64 65-74 

All races, both sexes Rate per 100 population 

Ever have trouble seeing ........................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses ......................................... 

Visited doctor about trouble seeing ......................... 

Ever miss school or.work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses ........................... 

Yes, glasses ......................................................... 

Yes, contact lenses .............................................. 

Yes, contact lenses and glasses ............... . ............ 

Still wear them.. ........................................................ 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision.. ............................................. 

At other times ..................................................... 

55.9 16.4 

11.6 

292.0 

3.1 

14.0 

41.3 

11.1 

94.0 

6.3 

88.4 

3.5 

58.9 

362.5 

30.6 

32.8 

88.9 

52.6 

90.3 

62.3 

57.8 

84.7 

58.7 

91.6 

66.9 

62.3 

3.4 

36.8 

35.2 

0.4 

1.1 

82.1 

57.8 

86.9 

71.2 

64.4 

50.2 50.7 54.8 

9.2 10.1 9.9 

93.4 93.0 91.5 

3.8 3.8 3.5 

53.0 54.2 58.8 

45.0 48.1 56.1 

1.1 1.1 0.4 

6.9 5.0 2.3 

82.9 77.6 79.2 

56.3 49.7 44.2 

83.4 82.9 85.5 

71.5 65.4 56.6 

64.0 57.8 51.5 

Percent distribution 

Age first worn:4 

O-4 years.. ............................................................ 

5-9 years.. ............................................................ 

1 O-19 years.. ........................................................ 

20-29 years.. ........................................................ 

30-39 years.. ........................................................ 

40-49 years .......................................................... 

50 years or older.. ................................................ 

31.2 

311.0 

333.9 

313.3 

310.5 

320.8 

39.3 

- 

3.8 

35.5 

60.7 

. . . 

. . . 

. . . 

. . . 

1.7 2.2 

20.0 15.5 

70.1 55.6 

8.2 23.7 

. . . 3.0 

. . . . . . 

. . . . . . 

Rate per 100 population 

1.3 

10.0 

37.9 

20.2 

20.5 

10.1 

. . . 

Male 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ....................................... 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ............................................ 

Yes, contact lenses and glasses.. .......................... 

Still wear them.. ........................................................ 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision ............................................... 

At other times ..................................................... 

50.5 15.1 34.3 43.1 45.4 48.1 80.4 82.2 83.7 

9.4 9.2 5.3 9.0 9.0 7.6 9.7 10.0 13.7 

93.5 293.3 90.5 91.9 91.1 92.0 94.5 96.6 95.9 

3.7 

52.5 

357.2 

30.4 

31.6 

88.9 

3.2 3.2 

12.3 30.9 

-- 30.3 

-- 

81.0 

0.7 

79.7 

3.5 4.6 4.4 3.5 

43.3 46.4 60.8 85.6 

39.9 43.0 48.7 84.1 

0.6 0.7 0.3 0.5 

2.8 2.7 1.8 1 .o 

84.4 75.9 81.2 96.0 

51.9 52.7 60.3 63.8 54.6 49.5 37.8 50.2 61.8 

90.6 89.3 90.2 85.5 85.5 83.2 93.1 95.0 97.3 

60.8 64.7 69.7 76.4 66.4 61.0 45.4 57.4 65.7 

57.2 56.5 66.1 72.5 62.5 58.9 41.7 52.3 65.0 

Percent distribution 

.Age first worn:’ 

O-4 years.. ............................................................ 

5-9 years.. ............................................................ 

1 O-l 9 years .......................................................... 

20-29 years.. ........................................................ 

30-39 years.. ........................................................ 

40-49 years.. ........................................................ 

50 years or older.. ................................................ 

_- 

-- 

__- 

___ 

-- 

___ 

2.7 

36.8 

60.5 

. . . 

. . . 

. . . 

. . . 

1.2 

20.7 

68.5 

9.7 

. . . 

. . . 

. . . 

1.5 1.7 

16.2 10.3 

51.5 28.1 

25.8 21.0 

5.0 25.5 

. . . 13.4 

. . . . . . 

See footnotes at end of table. 

82.7 85.8 86.7 

10.8 12.5 16.9 

94.8 97.7 97.6 

3.6 

89.3 

87.8 

0.5 

1.1 

96.8 

9:*x 

93:8 

0.1 

1.0 

98.5 

2.9 

96.7 

96.2 

0.1 

0.4 

97.8 

40.2 57.5 69.7 

93.9 96.5 98.1 

47.0 62.9 72.8 

44.3 59.7 72.0 

0.7 0.1 0.2 

3.8 3.1 3.1 

16.8 10.9 10.5 

12.2 13.7 10.2 

15.4 13.9 13.4 

46.0 35.0 29.8 

5.1 23.3 32.8 

9x:: 

91.4 

0.2 

0.7 

98.5 

3.0 

94.1 

93.6 

0.1 

0.4 

96.8 

0.6 

2.5 

12.6 

11.9 

14.0 

51.3 

7.1 

3.0 

6.4 

10.1 

12.1 

38.5 

30.0 

0.2 

2.2 

6.6 

6.8 

12.1 

30.0 

42.2 

79 
Table 34. Prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age lenses first worn, 

among population 6-74 years, by age, race, and sex: United States, 1971-1974-Con. 

Race, sex, and selected medical 

history items 

Age in years 

Female Rate per 100 population 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ....................................... 

Visited doctor about trouble seeing.. ........................ 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ........................................... 

Yes, contact lenses and glasses.. .......................... 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision ............................................... 

All other times.. ................................................... 

60.9 17.7 48.6 56.9 55.6 60.8 84.8 89.1 89.0 

12.3 13.5 7.0 9.4 10.8 11.6 11.8 14.6 19.2 

94.4 290.9 86.9 94.4 94.4 91.1 95.0 98.6 98.8 

3.4 3.1 3.5 4.1 3.0 2.7 3.7 

64.9 15.8 42.8 62.0 61.3 66.2 92.7 

‘67.4 -__ 40.4 49.8 52.7 62.9 91.2 

30.8 ___ 0.8 1.5 1.5 0.5 0.5 

33.9 -_ 1.6 10.6 7.0 2.8 1.1 

89.0 87.5 83.9 81.9 78.8 77.7 97.4 

53.2 63.5 55.8 51.5 46.2 40.6 42.2 63.7 75.3 

90.2 93.4 84.4 82.1 81 .I 87.1 94.6 97.7 98.6 

63.4 68.7 72.3 68.3 64.8 53.5 48.4 67.6 77.9 

58.2 66.9 63.0 58.6 54.5 46.3 46.6 65.9 76.9 

Percent distribution 

Age first worn:6 

O-4 years.. ............................................................ 

59 years .............................................................. 

1 O-l 9 years.. ........................................................ 

20-29 years.. ........................................................ 

30-39 years.. ........................................................ 

40-49 years.. ........................................................ 

50 years or older.. ................................................ 

31.4 --- 4.6 

311.2 -- 34.5 

337.8 -- 60.9 

313.8 - . . . 

310.3 --- . . . 

318.4 -- . . . 

36.9 -- . . . 

White, both sexes 

2.1 2.7 1.1 

19.6 15.1 9.8 

71.1 58.4 44.7 

7.2 22.2 19.7 

. . . 1.6 16.9 

. . . . . . 7.7 

. . . . . . . . . 

Rate per 100 population 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ....................................... 

Visited doctor about trouble seeing.. ........................ 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ........................................... 

Yes, contact lenses and glasses.. .......................... 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision ............................................... 

At other times ..................................................... 

55.5 16.3 42.8 52.0 52.1 55.3 84.2 86.6 87.5 

10.9 9.5 6.5 9.5 9.9 9.6 10.7 12.3 16.7 

94.7 294.3 88.7 94.6 93.6 91.9 95.5 98.4 98.0 

3.5 3.4 3.1 3.7 3.9 3.6 3.5 3.6 2.9 

60.9 14.5 38.0 55.4 56.0 59.2 91.5 96.2 97.6 

364.1 -__ 36.3 46.3 49.3 56.1 89.9 95.1 97.1 

30.6 ___ 0.4 1.3 1.3 0.4 0.5 0.1 0.0 

33.1 -__ 1.3 7.8 5.4 2.6 1.2 1.1 0.5 

89.4 83.6 83.6 84.1 77.3 79.9 96.7 99.0 98.1 

53.2 61.5 58.2 57.3 50.1 44.6 40.6 58.1 70.3 

90.3 90.6 85.9 83.2 83.3 84.9 93.9 97.0 98.2 

63.2 69.9 72.6 73.0 66.0 57.7 47.6 63.4 73.4 

58.3 65.1 65.3 65.0 57.9 52.0 44.5 60.0 72.4 

Percent distribution 

Age first worn:4 

O-4 years.. ............................................................ 

5-9 years.. ............................................................ 

IO-19 years.. ........................................................ 

20-29 years.. ........................................................ 

30-39 years.. ........................................................ 

40-49 years.. ........................................................ 

50 years or older.. ................................................ 

See footnotes at end of table. 

31.2 --- 3.7 

311.1 ___ 36.3 

334.2 ___ 60.0 

313.1 ___ 

. . . 

310.2 ___ . . . 

321.2 ___ . . . 

38.9 -__ . . . 

1.6 

20.5 

70.4 

7.5 

. . . 

. . . 

. . . 

2.3 

15.7 

57.0 

22.3 

2.7 

. . . 

1.5 

10.5 

38.9 

19.9 

19.1 

10.2 

. . . 

80 

4.2 

97.2 

96.0 

1.2 

98.5 

2.9 

98.6 

98.1 

0.0 

0.5 

98.5 

0.8 0.1 0.3 

4.9 3.2 3.7 

20.2 14.8 13.3 

12.4 16.8 12.7 

16.6 15.4 14.3 

41.6 32.0 29.7 

3.5 17.6 26.0 

0.7 0.1 0.2 

4.0 3.1 3.1 

16.8 11.7 10.9 

12.4 13.6 10.5 

14.8 14.1 13.6 

46.5 35.1 30.2 

4.8 22.4 31.5 
Table 34. Prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age lenses first worn, 

among population 6-74 years, by age, race, and sex: United States, 1971-1974-Con. 

Race, sex, and selected medical 

history items 

White male 

All Age in years 

ages. 

6-74 

years 6-11 1 12-17 18-24 25-34 3544 45-54 55-64 65-74 

Rate per 100 population 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ....................................... 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ........................................... 

Yes, contact lenses and glasses ............................. 

Still wear them.. ........................................................ 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision ............................................... 

At other times ..................................................... 

52.1 35.1 

9.3 

94.3 

5.8 

291.3 

3.7 

54.6 

359.0 

30.4 

31.7 

88.9 

15.5 

8.4 

95.7 

3.5 

12.5 

2.9 

31.4 

30.6 

52.3 

90.6 

61.4 

57.5 

_I 

_- 

78.7 

54.8 

87.5 

66.5 

59.0 

0.8 

80.8 

61.5 

88.8 

72.1 

68.0 

44.8 45.7 48.9 

9.7 8.1 7.3 

93.6 91.4 92.0 

3.5 4.9 4.5 

46.5 47.1 52.0 

42.5 43.5 49.6 

0.7 0.8 0.3 

3.3 2.8 2.0 

84.0 74.9 81.3 

63.5 54.7 49.3 

85.6 86.3 82.5 

76.2 67.0 61.6 

72.3 61.8 59.1 

Percent distribution 

Age first worn: 7 

O-4 years.. ............................................................ 

5-9 years.. ............................................................ 

IO-I 9 years .......................................................... 

20-29 years .......................................................... 

30-39 years .......................................................... 

40-49 years .......................................................... 

50 years or older.. ................................................ 

31.0 

310.8 

328.6 

312.6 

310.8 

324.3 

312.0 

3.1 1.2 

39.2 21.4 

57.7 68.3 

. . . 9.0 

. . . . . . 

. . . . . . 

. . . . . . 

1.7 

16.5 

52.6 

24.8 

4.4 

. . . 

1.8 

10.6 

28.6 

20.6 

24.7 

13.8 

. . . . . . 

White female Rate per 100 population 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses ......................................... 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ............................................ 

Yes, contact lenses and glasses.. .......................... 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision ............................................... 

At other times ..................................................... 

62.5 17.1 50.9 58.8 57.9 61.5 85.0 89.6 89.6 

12.1 

95.0 

7.1 9.4 11.1 11.3 11.3 14.7 18.9 

86.8 95.3 95.2 91.9 95.8 98.9 99.3 

3.3 

66.9 

368.8 

30.9 

34.3 

89.8 

10.4 

293.0 I 

3.2 

16.4 

__. 

_I 

__. 

87.4 

3.4 3.9 3.0 2.7 3.4 

45.0 63.9 64.2 66.1 93.9 

42.3 49.9 54.6 62.4 92.3 

0.9 1.8 1.7 0.5 0.5 

1.9 12.2 7.8 3.2 1.2 

85.7 84.2 78.8 78.8 97.5 

53.9 66.7 55.7 53.0 47.0 41.2 42.5 64.2 75.8 

90.1 92.9 83.7 81.6 81.3 86.6 94.8 98.0 98.6 

64.5 72.6 72.9 70.7 65.3 54.9 48.8 68.5 78.5 

58.8 69.8 63.4 60.1 55.2 46.9 46.6 66.1 77.4 

Percent distribution 

Age first worn:6 

O-4 years.. ............................................................ 

5-9 years .............................................................. 

1 O-l 9 years.. ........................................................ 

20-29 years.. ........................................................ 

30-39 years .......................................................... 

40-49 years .......................................................... 

50 years or older.. ................................................ 

31.4 _- 

311.4 ___ 

338.5 -- 

313.5 --_ 

39.8 -__ 

318.8 ___ 

36.6 ___ 

4.2 

34.1 

61.7 

1.9 

19.8 

71.9 

6.4 

. . . 

. . . 

. . . 

2.7 

15.1 

59.9 

20.7 

1.5 

. . . 

. . . 

1.3 

10.5 

46.7 

19.3 

14.8 

7.4 

. . . 

See footnotes at end of table. 

83.2 83.3 84.6 

10.0 9.4 13.6 

95.2 97.8 96.3 

3.7 3.3 2.8 

88.9 93.9 95.3 

87.2 92.9 94.9 

0.5 0.2 0.0 

1.1 0.8 0.4 

95.8 98.8 97.2 

38.3 51.3 62.5 

93.0 95.9 97.6 

46.3 57.7 66.4 

42.2 53.0 65.5 

0.6 

2.5 

13.0 

12.1 

14.3 

50.8 

6.7 

2.9 

6.8 

10.4 

12.1 

38.7 

29.0 

0.2 

2.3 

7.0 

7.0 

12.2 

30.5 

40.8 

3.7 

98.4 

97.0 

1.3 

99.2 

2.9 

99.3 

98.7 

0.0 

0.5 

98.7 

0.8 0.2 0.2 

5.3 3.3 3.7 

20.0 16.0 13.7 

12.7 16.3 13.0 

15.2 15.8 14.6 

42.8 31.9 30.0 

3.2 16.6 24.8 

81 
Table 34. Prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age lenses first worn, 

among population 6-74 years, by age, race, and sex: United States, 1971-I 974-Con. 

- 

Race, sex, and selected medical 

history items 

Black, both sexes 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ........................................ 

Visited doctor about trouble seeing.. ........................ 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ............................................ 

Yes, contact lenses and glasses.. ........................... 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision ............................................... 

At other times ..................................................... 

Age first worn:’ 

O-4 years.. ............................................................ 

5-9 years.. ............................................................ 

1 O-l 9 years.. ........................................................ 

20-29 years .......................................................... 

30-39 years.. ........................................................ 

40-49 years .......................................................... 

50 years or older.. ................................................ 

Black male 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ........................................ 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ............................................ 

Yes, contact lenses and glasses.. ........................... 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision.. ............................................. 

At other times ..................................................... 

Age first worn:g 

O-4 years .............................................................. 

5-9 years.. ............................................................ 

1 O-l 9 years.. ........................................................ 

20-29 years.. ........................................................ 

30-39 years .......................................................... 

40-49 years.. ........................................................ 

50 years or older.. ................................................ 

See footnotes at end of table. 

82 

Age in years 

6-11 1 12-17 18-24 25-34 3544 45-54 55-64 65-74 

Rate per 100 population 

41.4 16.2 

13.0 

86.7 

3.8 

42.8 

349.2 

30.1 

30.2 

82.8 

32.8 

4.3 

85.6 

5.0 

28.3 

28.3 

46.8 

91.2 

52.8 

52.9 

26.9 

278.0 

2.0 

11.6 

-__ 

___ 

___ 

91.5 

43.3 

98.4 

50.2 

47.0 

66.8 

52.6 

95.1 

57.7 

54.4 

31.0 -- 4.3 

39.4 -.v 28.4 

329.9 ___ 67.3 

316.4 -.- . . . 

313.2 ___ 

. . . 

316.3 -_ . . . 

313.8 _- . . . 

36.1 

10.5 

83.6 

3.6 

33.5 

338.8 

“02 

10.9 

16.0 

“75.5 

1.7 

10.3 

mm. 

-_ 

___ 

95.1 

29.6 

2.5 

83.7 

5.6 

25.5 

25.5 

85.9 

46.0 46.2 

91.1 ‘100.0 

51.6 61.5 

53.0 47.7 

66.8 

49.5 

99.3 

50.0 

50.4 

3- 

38.9 

326.6 

315.1 

39.4 

320.8 

319.1 

-_ 16.8 

___ 83.2 

-_ 

. . . 

___ 

. . . 

-_ 

. . . 

--_ . . . 

38.1 41 .o 46.8 

7.5 8.1 14.5 

81.2 86.9 87.7 

4.7 2.3 2.8 

34.6 38.4 54.2 

33.8 37.6 54.2 

0.1 0.1 

0.7 0.7 

68.3 78.2 69.5 

48.4 45.0 38.3 

88.8 77.0 91.9 

56.9 59.3 43.5 

539 57.8 44.5 

Percent distribution 

3.3 0.4 

16.4 15.3 

65.3 41.3 

14.9 41.2 

. . . 1.9 

. . . . . . 

. . . . . . 

27.7 44.7 31.7 

1.7 9.2 15.0 

68.2 87.6 97.5 

4.1 1.4 3.9 

14.3 37.9 32.6 

14.3 37.7 32.6 

0.2 

81.7 79.4 73.2 

77.4 55.0 41.9 

94.1 74.9 90.8 

89.3 63.2 44.3 

77.4 72.5 48.6 

Percent distribution 

6.3 

29.8 

23.1 

33.3 

7.6 

. . . 

Rate per 100 population 

18.6 16.5 

55.3 42.1 

26.1 40.6 

. . . 0.8 

. . . . . . 

. . . . . . 

9.3 

18.8 

28.0 

33.1 

10.9 

. . . 

68.2 76.3 78.9 

13.1 17.4 

86.2 89.1 

18.8 

93.2 

4.9 6.4 

68.3 80.2 

68.3 80.2 

97.3 92.6 

3.7 

88.1 

87.7 

0.4 

94.3 

35.2 52.3 63.5 

92.5 93.8 96.5 

39.7 54.7 66.4 

41 .o 58.7 67.4 

0.3 

1.6 

16.5 

9.8 

24.4 

38.1 

9.3 

3.1 

2.3 

16.3 

11.9 

29.0 

37.4 

0.2 

3.1 

6.3 

6.4 

11.5 

25.6 

46.9 

53.8 65.7 

5.7 21.7 

83.3 77.8 

2.6 7.0 

54.8 71.7 

54.8 71.7 

98.4 94.6 

27.9 39.9 

93.8 92.1 

30.7 46.4 

32.3 48.7 

2.3 

6.5 

10.7 

10.9 

56.5 

13.0 

4.4 

3.8 

13.8 

27.9 

50.1 

4.8 

81.9 

81.0 

0.9 

53.4 

93.3 

58.0 

60.0 

1.2 

1.4 

4.2 

11.4 

24.4 

57.5 
Table 34. Prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age lenses first worn, 

among population 6-74 years, by age, race, and sex: United States, 1971-1974-Con. 

All 

Race, sex, and selected medical Age in years 

ages, 

history items 6-74 

years 6-l 1 l 12-17 18-24 25-34 3544 45-54 55-64 65-74 

Black female Rate per 100 population 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses .......................................... 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses ............................ 

Yes, glasses .......................................................... 

Yes, contact lenses.. .. :. ......................................... 

Yes, contact lenses and glasses.. ........................... 

Still wear them.. ........................................................ 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision.. ............................................. 

At other times ..................................................... 

Age first worn? 

O-4 years.. ............................................................ 

5-9 years.. ............................................................ 

1 O-l 9 years .......................................................... 

20-29 years.. ........................................................ 

30-39 years.. ........................................................ 

40-49 years.. ........................................................ 

50 years or older.. ................................................ 

50.0 

14.5 

88.6 

4.0 

50.8 

357.8 

30.0 

30.4 

81.0 

47.2 40.9 55.7 

91.2 97.1 91.0 

53.5 40.9 65.2 

52.9 46.5 58.3 

31.6 

39.7 

331 .8 

317.1 

315.3 

313.8 

310.8 

21.3 36.0 

35.6 6.1 

279.7 87.3 

2.3 4.4 

12.8 31.1 

I_ 31.1 

88.6 66.8 

I 8.4 

39.3 

52.3 

. . . 

. . . 

. . . 

. . . 

46.4 37.6 

8.8 7.1 

87.4 86.2 

5.1 3.0 

50.6 38.8 

49.2 37.5 

0.2 - 

1.2 1.3 

65.3 77.2 

41.7 36.3 

87.6 78.9 

49.3 56.0 

48.6 44.7 

55.9 82.1 83.7 83.0 

14.3 17.9 15.0 22.4 

84.3 88.0 95.2 94.1 

2.1 7.2 6.0 2.9 

67.4 81.3 86.1 92.7 

67.4 81.3 86.1 92.7 

68.4 96.6 91.5 95.7 

37.2 40.1 59.1 70.1 

92.2 91.6 94.7 98.7 

43.3 45.5 59.1 71.9 

43.2 469 64.2 72.2 

Percent distribution 

4.1 I 0.7 

15.9 14.2 

67.6 40.5 

12.4 41.7 

. . . 2.9 

. . . . . . 

. . . . . . 

‘Questions were answered by parent. 

2Visited doctor about vision problem other than trouble seeing at night or in dark. 

‘Does not include 6-11 years. 

4Average age is 7.1 years. 

5Average age is 7.4 years. 

6Average age is 6.9 years. 

‘Average age is 7.3 years. 

‘Average age is 7.2 years. 

‘Average age is 7.5 years. 

6.4 

33.0 

21.6 

33.3 

6.7 

. . . 

0.5 

1.1 

23.1 

9.3 

33.1 

26.0 

6.8 

2.4 

3.6 

23.6 

10.9 

29.6 

30.0 

0.3 

4.4 

9.7 

7.8 

11.6 

26.5 

39.8 

83 
Table 34A. Standard errors for prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age 

lenses first worn, among population 6-74 vealrs. bv aae. race. and sex: United States. 1971-1974 

Race, sex, and selected medical 

history item 

All 

ages, --I Age in years 

6-74 

years 8-l 11 12-17 18-24 25-34 3544 45-54 55-64 65-74 

All races, both sexes Standard error of rate 

Ever have trouble seeing.. ........................................ 0.67 1 .oo 1.49 1.47 1.49 1.19 1.03 1.56 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ...................................... 0.49 2.46 1.22 1.18 1.18 1.08 0.95 1.12 

Visited doctor about trouble seeing ........................ 0.38 ,'2.36 1 .I6 0.92 1.02 1 .oo 0.70 0.51 

Ever miss school or work because of trouble with 

eyes ..................................................................... 0.26 0.48 0.53 0.50 0.52 0.56 0.70 0.67 

Ever wear glasses or contact lenses.. ........................ 0.45 0.82 1.44 1.13 1.39 ,I.26 0.74 0.75 

Yes, glasses ........................................................ 30.47 --_ 1.46 1.18 1.34 1.23 0.83 0.89 

Yes, contact lenses.. .......................................... 30.10 I_ 0.15 0.29 0.27 0.14 0.27 0.08 

Yes, contact lenses and glasses.. _I ......................... 30.24 0.37 0.58 0.73 0.41 0.31 0.39 

Still wear them.. ...................................................... 0.46 2.99 1.67 1.57 1.54 1.39 0.62 0.39 

When worn: 

All the time ....................................................... 0.92 4.44 2.27 1.98 1.61 1.86 1.57 1.95 

For reading or close work.. ................................ 0.41 1.85 1.46 1.47 1.42 1.37 0.77 0.98 

For distance vision.. ........................................... 0.82 4.65 1.83 1.71 1.51 1.77 1.52 1.74 

At other times ................................................... 0.87 4.16 2.40 1.84 1.63 1.87 1.66 1.99 

1.00 

0.84 

0.33 

0.43 

0.33 

0.36 

K 

0:30 . 

1.41 

0.35 

1.26 

1.40 

Standard error of percent 

Age first worn:4 

O-4 years.. 30.14 .- .......................................................... 0.91 0.47 0.41 0.43 0.23 0.08 

5-9 years.. _I .......................................................... 30.43 2.11 1.39 1.19 1.26 0.69 0.59 

IO-I 9 years.. _I ...................................................... 30.58 1.99 1.93 1.69 1.84 0.93 1.26 

20-29 years -- ........................................................ 30.46 . . . 1.28 1.51 1.50 0.96 1.38 

30-39 years.. ...................................................... 30.45 . . . . . . 0.71 1.70 1.30 1.16 

40-49 years.. ...................................................... 30.53 _I 

. . . . . . . . . 1.15 1.67 1.68 

50 years or older.. .............................................. 30.33 . . 

. . * . . . . * . . . . 0.73 1.21 

0.15 

0.61 

0.79 

0.66 

0.69 

1.11 

1 .22 

Male Standard error of rate 

Ever have trouble seeing.. ........................................ 0.94 1.28 1.77 2.38 2.80 2.61 1.42 1.98 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ..................................... 0.70 3.02 2.10 2.31 1.93 1.96 1.31 1.63 

Visited doctor about trouble seeing ........................ 0.47 224.05 1.84 1.86 2.26 1.63 0.96 0.93 

Ever miss school or work because of trouble with 

eyes ..................................................................... 0.42 0.73 0.60 0.76 1.13 0.91 1.01 1.01 

Ever wear glasses or contact lenses.. ........................ 0.64 1.16 1.86 2.19 2.21 2.33 1.45 1.58 

Yes, glasses ........................................................ 30.64 -- 1.75 2.28 2.21 2.25 1.35 1.74 

Yes, contact lenses.. .......................................... 30.12 --- 0.44 0.32 0.21 0.33 0.16 

Yes, contact lenses and glasses .......................... 30.20 --- 0.35 0.73 0.66 0.72 0.44 0.64 

Still wear them.. ...................................................... 0.62 5.31 2.54 2.04 2.71 1.94 1 .oo 0.51 

When worn: 

All the time ....................................................... 1.05 4.93 3.47 3.68 3.06 3.55 2.24 2.74 

For reading or close work.. ................................ 0.59 3.22 2.20 2.50 2.62 2.44 1.18 1.86 

For distance vision ............................................. 1.02 5.92 3.75 3.06 2.79 3.03 2.23 2.63 

At other times ................................................... 0.94 4.82 3.07 3.35 3.03 3.55 2.19 2.86 

1.47 

0.81 

0.69 

0.55 

0.63 

0.67 

0.10 

0.17 

0.53 

1.69 

0.63 

1.78 

1.72 

Standard error of percent 

Age first worn:’ 

O-4 years.. .......................................................... 

58 years.. .......................................................... 

IO-19 years.. ...................................................... 

20-29 years.. ...................................................... 

30-39 years.. ...................................................... 

40-49 years.. ...................................................... 

50 years or older.. .............................................. 

See footnotes at end of table. 

1.14 0.62 0.49 0.88 0.36 - 

3.94 2.39 2.22 2.28 0.77 1 0.89 

3.74 3.23 3.50 3.66 1.54 1.16 

. . . 2.50 2.77 2.86 1.44 1.55 

. . . . . . 1.69 3.08 1.54 1.72 

. . . . . . 2.30 2.37 2.71 

. . . . . . . . . . . . 1.35 1.78 

0.13 

0.55 

0.95 

0.91 

0.97 

1.29 

1.83 

84 
Table 34A. Standard errors for prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age 

lenses first worn, among population 6-74 years, by age, race, and sex: United States, 1971-1974-Con. 

Race, sex, and selected medical 

history item 

Female Standard error of rate 

Ever have trouble seeing.. ........................................ 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. .................................... 

Visited doctor about trouble seeing ........................ 

Ever miss school or work because of trouble with 

eyes ..................................................................... 

Ever wear glasses or contact lenses.. ........................ 

Yes, glasses ........................................................ 

Yes, contact lenses.. ......................................... 

Yes, contact lenses and glasses.. ........................ 

Still wear them.. ...................................................... 

When worn: 

All the time ....................................................... 

For reading or close work.. ................................ 

For distance vision ............................................. 

At other times ................................................... 

0.75 1.62 2.25 1.62 1.37 

I 

1.32 

0.59 3.66 1.66 

0.46 23.69 1.61 

0.24 

0.66 

30.75 

30.13 

30.37 

0.65 

0.72 

1.28 

- 

- 

3.22 

0.73 

2.12 

2.23 

0.31 

0.66 

1.99 

1.23 5.78 3.31 

0.58 2.79 2.33 

1.03 5.19 2.74 

1.14 5.71 3.11 

1.12 1.36 1.21 

0.71 0.96 1.03 

0.68 0.41 0.54 

1.25 1.58 1.38 

1.27 1.67 1.58 

0.40 0.38 0.20 

0.94 1 .oo 0.60 

2.12 1.63 1.75 

2.13 1.80 2.07 

1.50 1.48 1.57 

1.86 1.76 2.21 

2.01 1.69 2.02 

Standard error of percent 

Age first worn:6 

O-4 years ............................................................ 

5-9 years ............................................................ 

1 O-l 9 years.. ...................................................... 

20-29 years ........................................................ 

30-39 years ........................................................ 

4049 years.. ...................................................... 

50 years or older.. .............................................. 

White, both sexes 

Ever have trouble seeing .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. .................................... 

Visited doctor about trouble seeing ........................ 

Ever miss school or work because of trouble with 

eyes ..................................................................... 

Ever wear glasses or contact lenses.. ........................ 

Yes, glasses ........................................................ 

Yes, contact lenses.. ......................................... 

Yes, contact lenses and glasses.. ....................... 

Still wear them ........................................................ 

When worn: 

All the time ....................................................... 

For reading or close work.. ................................ 

For distance vision.. ........................................... 

At other times ................................................... 

Age first worn: 7 

O-4 years ............................................................ 

5-9 years ............................................................ 

1 O-l 9 years.. ...................................................... 

20-29 years.. ...................................................... 

30-39 years ........................................................ 

40-49 years ........................................................ 

50 years or older ................................................ 

See footnotes at end of table. 

All 

ages, 

6-74 

years 

Age in years 

6-11 1 12-17 IS-24 25-34 3544 45-54 55-64 65-74 

30.17 

30.58 

30.77 

30.60 

30.47 

30.61 

30.37 

0.72 

0.51 

0.42 

0.29 

0.49 

30.50 

30.11 

30.26 

0.43 

1.03 

0.42 

0.92 

0.97 

30.15 

30.46 

30.64 

30.47 

30.45 

30.61 

30.33 

- 

-- 

-_ 

- 

_- 

_- 

1.06 

2.53 

22.32 

0.54 

1.02 

3.35 

4.48 

2.21 

4.86 

4.14 

- 

_- 

-_ 

-- 

_- 

-__ 

1.17 

2.95 

3.05 

. . . 

. . . 

. . . 

. . . 

0.61 0.59 0.38 

1.76 1.40 1.19 

1.95 1.68 1.67 

0.95 1.72 1.49 

. . . 0.39 1.61 

. . . . . . 1.16 

. . . . . . . . . 

Standard error of rate 

0.22 

1.19 

I.75 

1.27 

1.71 

2.06 

0.65 

0.15 

0.7s 

1.84 

2.04 

1.75 

2.35 

1.83 

0.23 

0.86 

1.08 

0.88 

0.94 

1.56 

1.31 

1.57 1.56 1.53 1.33 1.18 1.68 1.09 

1.28 1.34 I .20 1.16 0.97 1.25 0.90 

1.36 1.02 1.08 1.06 0.83 0.49 0.34 

0.60 0.61 0.61 0.60 0.79 0.62 0.44 

1.55 1.29 1.45 1.50 0.73 0.85 0.34 

1.58 1.38 1.38 1.48 0.85 0.95 0.37 

0.18 0.34 0.31 0.16 0.30 0.08 0.02 

0.42 0.70 0.80 0.46 0.34 0.43 0.18 

1.67 1.45 1.71 1.33 0.56 0.28 0.29 

2.52 2.09 1.79 1.96 1.65 2.11 1.52 

1.59 1.50 1.42 1.53 0.70 0.98 0.37 

1.83 1.83 1.62 1.87 1.66 1.91 1.34 

2.56 1.93 1.87 1.95 1.75 2.12 1.51 

Standard error of percent 

1.03 

2.27 

2.29 

. . . 

. . . 

. . . 

. . . 

0.46 0.44 

1.37 1.22 

1.83 1.65 

1.24 1.51 

. . . 0.66 

. . . . . . 

. . . . . . 

0.48 

1.43 

1.93 

1.57 

1.76 

1.35 

. . . 

0.24 0.09 0.16 

0.74 0.65 0.67 

1 .oo 1.36 0.88 

0.99 1.49 0.76 

1.26 1.22 0.77 

1.80 1.75 1.14 

0.80 1.25 1.15 

1.68 1.94 

1.47 1.89 

0.98 0.54 

0.78 0.97 

1.14 0.83 

1.26 0.99 

0.31 - 

0.45 0.53 

0.49 0.54 

2.31 2.64 

1.06 0.72 

2.12 2.40 

2.35 2.47 

1.05 

1.32 

0.27 

0.66 

0.26 

0.36 

0.01 

0.26 

0.32 

1.88 

0.38 

1.77 

1.75 

85 
Table 34A. Standard errors for prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age 

lenses first worn, among population 6-74 years, by age, race, and sex: United States, 1971-1974-Con. 

Race, sex, and selected medical 

history item 

Age in years 

3544 ) 45-54 j 55-64 I 65-74 

White male Standard error of rate 

Ever have trouble seeing.. ........................................ 1.02 1.42 1.95 2.65 2.87 2.75 1.68 2.01 1.56 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. .................................... 0.69 3.32 2.42 2.52 1.78 2.05 1.38 1.76 0.86 

Visited doctor about trouble seeing ........................ 0.50 “3.58 1.90 1.87 2.48 1.69 1.06 0.80 0.76 

Ever miss school or work because of trouble with 

eyes ..................................................................... 0.46 0.84 0.66 0.90 1.26 0.95 1.09 1.04 0.61 

Ever wear glasses or contact lenses.. ........................ 0.69 1.28 2.08 2.54 2.29 2.58 1.36 1.72 0.65 

Yes, glasses ........................................................ 30.69 --- 1.96 2.63 2.21 2.50 1.33 1.81 0.67 

Yes, contact lenses.. ......................................... 30.13 ___ 0.50 0.38 0.23 0.37 0.18 0.05 

Yes, contact lenses and glasses.. ........................ 30.21 ___ 0.41 0.86 0.66 0.79 0.49 0.70 0.18 

Still wear them.. ...................................................... 0.63 6.05 2.68 2.23 3.05 1.95 1.06 0.52 0.47 

When worn: 

All the time ....................................................... 1.18 5.41 3.62 3.65 3.26 3.64 2.53 2.86 1.87 

For reading or close work.. ................................ 0.59 3.69 2.57 2.53 2.64 2.78 1.26 1.86 0.54 

For distance vision ............................................. 1.18 6.40 3.94 3.21 3.02 3.36 2.55 2.65 1.94 

At other times ................................................... 1.11 5.71 3.08 3.52 3.40 3.64 2.37 2.98 1.92 

Standard error of percent 

Age first worn:8 

O-4 years.. .......................................................... 30.22 __- 1.31 0.66 0.54 0.95 0.38 0.14 

5-9 years.. .......................................................... 30.64 ___ 4.17 2.38 2.31 2.46 0.84 0.90 0.59 

IO-19 years.. .......................................... .:.......... 50.93 I_ 3.97 3.21 3.27 3.80 1.63 1.24 1.03 

20-29 years.. ...................................................... 30.63 _-_ 

. . . 2.41 2.78 2.91 1.58 1.70 1 .oo 

30-39 years.. ...................................................... 30.84 -_- 

. . . . . . 1.55 3.19 1.64 1.75 1.03 

40-49 years.. ...................................................... 31 .oo _I 

. . . . . . . . . 2.55 2.54 2.64 1.32 

50 years or older.. .............................................. 30.56 -__ 

. . . . . . . . . . . . 1.36 1.88 1.79 

White female Standard error of rate 

Ever have trouble seeing.. ........................................ 0.78 1.65 2.31 1.79 1.52 1.41 1.74 2.08 1.14 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ...................................... 0.64 3.69 1.76 1.29 1.40 1.32 1.48 2.02 1.40 

Visited doctor about trouble seeing ........................ 0.51 “3.58 1.85 0.81 0.87 1.19 1.13 0.56 0.26 

Ever miss school or work because of trouble with 

eyes ..................................................................... 0.26 0.83 0.85 0.72 0.43 0.60 0.86 0.85 0.72 

Ever wear glasses or contact lenses.. ........................ 0.66 1.52 2.13 1.43 1.72 1.58 1 .oo 0.54 0.27 

Yes, glasses ........................................................ 30.74 -- 2.29 1.56 1.85 1.83 1.18 0.80 0.39 

Yes, contact lenses.. .......................................... 30.15 _- 0.36 0.48 0.43 0.23 0.34 0.02 

Yes, contact lenses and glasses.. ........................ 30.41 -- 0.76 1.10 1.10 0.69 0.50 0.59 0.29 

Still wear them.. ...................................................... 0.57 3.45 1.91 1.99 1.72 1.70 0.52 0.34 0.33 

When worn: 

All the time ....................................................... 1.34 5.82 3.75 2.22 1.93 2.39 2.41 2.94 2.11 

For reading or close work.. ................................ 0.59 3.21 2.56 1.61 1.50 1.66 1 .Ol 0.67 0.42 

For distance vision ............................................. 1.09 5.25 2.76 2.03 1.85 2.33 2.15 2.71 2.00 

At other times ................................................... 1.24 5.63 3.38 2.00 1.86 2.34 2.55 2.72 1.93 

Standard error oi fP lercent 

Age first worn:6 

O-4 years.. .......................................................... 30.17 -__ 1.19 0.59 0.63 0.44 0.24 0.16 

5-9 years.. 30.62 ___ .......................................................... 3.14 1.90 1.48 1.30 1.22 0.87 

1 O-l 9 years.. ...................................................... 30.84 _-_ 3.45 1.90 1.73 1.71 1.81 1.98 

20-29 years.. ___ ...................................................... 30.63 . . . 1 .oo 1.70 1.56 1.37 2.21 

30-39 years.. ...................................................... 30.51 _-- . . . . . . 0.39 1.53 1.67 1.88 

40-49 years.. ...................................................... 30.64 _- . . . * . . . . . 1.18 2.04 2.37 

50 years or older.. _- .............................................. 30.35 . . . . . . * . . . . . 0.79 1.71 

See footnotes at end of table. 

0.25 

0.95 

1.20 

1.06 

1.06 

1.61 

1.27 

86 
Table 34A. Standard errors for prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age 

lenses first worn, among population 6-74 years, bv age, race, and sex: United States, 1971-1974-Con. 

Race, sex, and selected medical 

history item 

Black, both sexes 

All 

ages. 

6-74 

years 6-11’ 12-17 

Age in years 

IS-24 25-34 3544 45-54 55-64 65-74 

Standard error of rate 

Ever have trouble seeing.. ........................................ 1.40 2.41 3.08 4.36 3.39 3.63 3.91 3.59 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ..................................... 1.58 8.39 1.85 2.68 2.94 3.56 3.89 4.24 

Visited doctor about trouble seeing ........................ 1.27 211.78 4.08 3.14 3.56 2.61 3.47 3.86 

Ever miss school or work because of trouble with 

eyes ..................................................................... 0.67 0.79 1.40 1.44 0.82 1.34 1.82 2.90 

Ever wear glasses or contact lenses.. ........................ 1.40 1.83 3.58 3.60 3.84 3.62 3.80 5.13 

Yes, glasses ........................................................ 31.40 _*_ 3.58 3.57 3.68 3.62 3.80 5.13 

Yes, contact lenses.. ......................................... 30.04 *** 0.09 0.10 - 

Yes, contact lenses and glasses.. ....................... 30.10 **- 0.40 0.51 - 

Still wear them.. ...................................................... 1.79 2.88 7.86 5.57 5.44 5.55 1.15 3.43 

When worn: 

All the time ....................................................... 2.12 9.62 8.20 6.41 5.28 5.02 4.08 6.56 

For reading or close work.. ................................ 1.30 1.29 1.60 3.07 5.54 2.02 3.99 3.76 

For distance vision.. ........................................... 2.17 10.07 7.97 5.85 6.32 5.59 4.43 5.96 

At other times ................................................... 2.24 9.07 8.02 6.63 5.29 5.50 5.50 6.35 

2.05 

1.90 

1.44 

1.23 

1.79 

1.85 

0.42 

1.44 

3.23 

0.88 

3.15 

2.83 

S tandard error of percent 

Age first worn:g 

O-4 years.. .......................................................... 30.46 *I 3.34 2.18 0.34 0.31 

5-9 years.. .......................................................... 31.30 -* 5.15 4.42 4.62 2.65 1.16 1.79 

1 O-1 9 years ........................................................ 31.46 *** 4.90 5.52 7.09 4.83 5.36 0.74 

20-29 years.. ...................................................... 31.54 -* . . . 3.46 5.48 4.79 2.28 4.19 

30-39 years.. ...................................................... 31.68 *- . . . . . . 1.20 5.27 5.31 4.60 

40-49 years ........................................................ 31.66 -* . . . . . . . . . 2.51 4.91 5.26 

50 years or older.. .............................................. 31 .08 -* . . . . . . 1.56 6.42 

0.20 

0.88 

1.57 

2.09 

2.31 

2.84 

4.50 

Slack male Standard error of rate 

Ever have trouble seeing.. ........................................ 1.85 2.57 3.90 5.71 6.58 5.80 7.03 7.73 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. .................................... 2.53 10.89 2.37 1.72 6.45 9.92 2.61 8.41 

Visited doctor about trouble seeing ........................ 2.25 220.64 5.44 11.11 7.06 1.82 5.63 10.40 

Ever miss school or work because of trouble with 

eves ..................................................................... 1.05 0.83 2.35 1.98 1.04 3.15 1.36 4.37 

Ever wear glasses or contact lenses.. ........................ 1.94 3.12 4.47 4.06 6.62 6.10 6.24 7.98 

Yes, glasses ........................................................ 31 .96 *- 4.47 4.06 6.63 6.10 6.24 7.98 

Yes, contact lenses .......................................... . 

- 0.22 

Yes, contact lenses and glasses.. 

“0.0,8 

....................... - 

Still wear them.. ...................................................... 2.87 2.95 8.68 12.37 11.80 11.85 0.92 2.09 

When worn: 

All the time ....................................................... 4.35 18.98 11.52 13.00 9.66 13.71 7.95 12.75 

For reading or close work.. ................................ 2.54 0.71 5.68 10.82 5.15 3.63 6.09 

For distance vision.. ........................................... 4.27 19.06 11.42 8.92 13.43 13.46 8.16 10.55 

At other times ................................................... 4.08 19.10 11.46 13.00 6.62 14.19 7.85 13.70 

3.01 

3.11 

2.14 

2.20 

3.56 

3.68 

0.98 

2.65 

4.28 

2.20 

4.33 

3.63 

Standard error of percent 

Age first worn:l’ 

O-4 years ............................................................ 3- - 

5-9 years ............................................................ 32.64 -* 6.17 12.56 10.74 8.03 2.10 4.54 

10-I 9 years.. ...................................................... 33.41 - 6.17 17.31 13.49 9.90 3.81 

20-29 years.. ...................................................... 32.93 *- 

. . . 14.42 11.15 11.07 5.00 1.99 

30-39 years ........................................................ 32.53 -* 

. . . ..* 0.92 13.58 4.19 8.32 

40-49 years.. ...................................................... 32.23 * . . . . . . . . 9.36 8.09 6.71 

50 years or older.. .............................................. 32.36 **_ 

. . . . . . . . . . . . 7.33 10.25 

1.26 

0.61 

1.59 

3.77 

3.45 

4.27 

See footnotes at end of table. 

87 
Table 34A. Standard errors for prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age 

lenses first worn, among population 6-74 years, by age, race, and sex: United States, 1971-1974-Con. 

. _ 

Race, sex, and selected medical 

history item 

All 

ages. 

6-74 

years 6-11’ 

Age in years 

12-17 18-24 25-34 3644 4564 56-64 65-74 

Black female Standard error of rate 

Ever have trouble seeing.. ........................................ 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. .................................... 

Visited doctor about trouble seeing ........................ 

Ever miss school or work because of trouble with 

eyes ..................................................................... 

Ever wear glasses or contact lenses.. ........................ 

Yes, glasses ........................................................ 

Yes, contact lenses.. ........................................... 

Yes, contact lenses and glasses.. .......................... 

Still wear them ........................................................ 

When worn: 

All the time ....................................................... 

For reading or close work.. ................................ 

For distance vision.. ........................................... 

At other times ................................................... 

Age first worn:ll 

O-4 years.. .......................................................... 

5-9 years.. .......................................................... 

IO-19 years.. ...................................................... 

20-29 years.. ...................................................... 

30-39 years.. ...................................................... 

40-49 years.. ...................................................... 

50 years or older.. .............................................. 

2.07 4.35 4.31 

1.45 1.3.94 2.86 

1.37 214.92 5.17 

0.78 1.31 

1.83 2.58 

31.82 -- 

30.03 ___ 

30.18 _- 

2.44 4.95 

1.66 

6.03 

5.03 

11.54 

2.46 13.61 9.82 

1.61 2.45 3.35 

2.47 13.61 9.02 

2.40 1 il.94 9.52 

30.72 ___ 

31.43 -__ 

32.40 -- 

31.78 _- 

32.09 -_ 

31.93 _- 

31.46 -- 

6.87 

8.24 

8.86 

. * . 

. . . 

. . . 

. . . 

5.05 2.75 4.18 

3.23 2.52 3.33 

2.98 3.45 3.54 

1.87 1.27 0.82 

4.03 3.70 3.62 

4.13 3.46 3.62 

0.16 

0.70 0.93 

7.24 5.01 5.12 

7.28 4.90 5.13 

3.68 5.81 2.55 

6.61 6.78 5.55 

8.11 6.45 5.60 

standard error of percent 

2.63 

4.32 

5.15 

2.77 

. . . 

. . . 

. . . 

‘Questions were answered by parent. 

‘Visited doctor about vision problem other than trouble seeing at night or in dark. 

3Does not include 6-11 years. 

4Standard error of average age is 0.2 1. 

‘Standard error of average age is 0.32. 

‘Standard error of average age is 0.24. 

‘Standard error of average age is 0.22. 

‘Standard error of average age is 0.37. 

‘Standard error of average age is 0.25. 

“Standard error of average age is 0.42. 

‘IStandard error of average age is 0.50. 

0.60 

2.90 

6.02 

6.62 

1.85 

. . . 

. . . 

2.14 

6.00 

5.45 

5.73 

2.16 

. . . 

4.46 4.39 2.81 

5.51 5.65 2.53 

4.76 2.16 1.97 

3.35 3.94 1.34 

5.88 6.23 1.57 

5.88 6.23 1.57 

1 .B7 5.17 1.51 

7.36 6.23 3.67 

6.25 4.42 0.39 

7.59 6.08 3.68 

8.41 5.69 3.67 

0.52 

1.30 

8.10 

3.44 

9.39 

5.51 

4.76 I 1.29 

1.09 

5.97 

4.61 

6.82 

7.14 

0.33 

1.09 

2.45 

2.97 

2.36 

3.93 

5.20 

88 
Table 35. Percent of total population age 8-74 years who Still wear glasses and peroent distribution of their usual visual acuity 11~1s in 

the better eye, by age and sex: United Steter, i971-1972 

Ane and sex 

goth sexes 

All onas, 8-74 years ..r..........r...................................................**..*.......,,,.,, 

9-11 years ................................................................................................................. 

12-l 7 year5 ............................................................................................................... 

1844 years ............................................................................................................... 

45-54 yarn ............................................................................................................... 

5594 year5 ............................................................................................................... 

86-74 years ............................................................................................................... 

Mate 

All ages, 6-74 years ........................................................................................ 

6-11 years ................................................................................................................. 

12-I 7 year5 ............................................................................................................... 

1844 year5 ...................................... . ........................................................................ 

4554 years ............................................................................................................... 

5584 years ............................................................................................................... 

85-74 year5 ............................................................................................................... 

Female 

All ages, 8-74 years ........................................................................................ 

8-11 years ......................................................................................... . ....................... 

12-17 years ............................................................................................................... 

1844 years ............................................................................................................... 

4554 years ............................................................................................................... 

55-84 years ............................................................................................................... 

65-74 years ............................................................................................................... 

‘From Medical History questionrmire. 

of total 

goputation~ 

$2.1 

1l.S 

2: 

98:2 

93.1 

94.1 

48.4 

2Zf 

37:4 

8149 

2: 

57.5 

13.7 

35.9 

49.8 

Et: 

98.8 

- 1 

T Percent distribution 

100.6 

- 

160.6 

196.6 

100.0 

100.0 

160.0 

100.9 

100.0 

m.0 

160.6 

lOl3.6 

100.d 

loo.0 

100.9 

100x) 

NOD 

loo.0 

100.0 

190.0 

100.0 

106.0 

70.8 

E 

88:4 

73.5 

82.1 

382 

73.8 

564 

89A9 

8763 

77.9 

Ef 

89.4 

528 42.1 

78.8 19.7 

855 12.3 

70.5 28.1 

40*7 

1545 

12.1 

24.7 

35.3 

53x) 

23.4 

38.8 

IQ.0 

11.7 

19.9 

31.2 

5264 

29.2 

8.2 

0.1 

1 .o 

i:f 

10.5 

3A 

5.1 

1.7 

1.8 

1.4 

2.2 

11.1 

89 
Table 36. Percent of total population age 6-74 years who still wear glasses and percent distribution of their maximum visual acuity levels 

in the better eye,l by age and sex: United States, 1971-1972 

Age and sex 

Both sexes 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . . . . . . . . . . . . . . . . . . . . . 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.1 I 

6-11 years ................................................................................................................. 

12-l 7 years.. ............................................................................................................. 

18-44 years.. ............................................................................... . . ............................. 

45-54 years.. ............................................................................... . .............................. 

56-64 years ............................................................................................................... 

65-74 years ................................................................................. ............................. 

Male 

All ages, 6-74 years .......................................................... .I.. ........................... 

6-11 years ................................................................................................................. 

12-17 years.. ............................................................................................................. 

1 B-44 years ............................................................................................................... 

45-54 years.. ............................................................................................................. 

55-64 years ............................................................................................................... 

65-74 years ............................................................................................................... 

Female 

All ages, 6-74 years.. ...................................................................................... 

6-11 years ................................................................................................................. 

12-17 years.. ............................................................................................................. 

18-44 years.. ............................................................................................................. 

45-54 years.. ............................................................................................................. 

5564 years ............................................................................................................... 

65-74 years ............................................................................................................... 

Percent 

of total 

11.8 

30.1 

43.9 

86.2 

93.1 

94.1 

46.4 

9.9 

24.5 

37.4 

81.9 

90.4 

90.5 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

59.7 38.6 

89.8 IO.21 

87.9 11.7 

79.0 19.7 

66.8 30.2’ 

37.9 55.4. 

57.5 69.1 

13.7 100.0 52.8 

35.8 100.0 78.9 

49.8 100.0 86.0 

90.2 100.0 72.0 

95.4 100.0 60.8 

96.8 100.0 36.2 

II Maximum visual acuity 

Percent distribution 

71.4 26.6 2.0 

55.6 

83.7 

86.8 

75.0 

63.4 

36.9 

42.0 2.4 

15.7’, 0.6 

12.5 0.7 

24.9 1 .o 

34.9 1.7 

55.6 7.5 

74.4 23.6 2.0 

1.8 

0.4 

1.3 

3.0 

6.7 

28.8. 

-- 

44.4 

20.01 

13.1 

27.1 

38.4 

55.8 

2.1 

2.8 

1.1 

0.9 

X f 

8.0 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spheri.cal 

refraction or retinoscopy for the remainder. 

‘From Medical History questionnaire. 

90 
Table 37. Percent of total population age 6-74 years who wear glasses and have no trouble seeing with them and percent distribution of 

their usual visual acuity levels in the better eye, by age and sex: United States, 1971-1972 

Age and sex 

Both sexes 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45.7 

6-I 1 years.. ............................................................................................................... 10.2 

12-17 years ............................................................................................................... 27.9 

1844 years.. ............................................................................................................. 38.5 

45-54 years.. ............................................................................................................. 76.6 

55-64 years ............................................................................................................... 81.4 

65-74 years ............................................................................................................... 77.9 

Male 

All ages, 6-74 years ........................................................................................ 

6-11 years.. ............................................................................................................... 

12-17 years ............................................................................................................... 

1844 years.. ............................................................................................................. 

45-54 years ............................................................................................................... 

5564 years ............................................................................................................... 

65-74 years ............................................................................................................... 

Female 

All ages, 6-74 years ........................................................................................ 

6-I 1 years.. ............................................................................................................... 

12-l 7 years ............................................................................................................... 

18-44 years ............................................................................................................... 

45-54 years.. ............................................................................................................. 

5564 years.. ............................................................................................................. 

65-74 years.. ............................................................................................................. 

Percent 

of total 

population’ 

41.5 

8.8 

22.9 

33.5 

73.7 

81.3 

77.8 

49.6 

11.6 

32.9 

43.1 

79.3 

81.3 

78.0 

- 1 

I 

Usual visual acuity 

I I 

100.0 73.0 24.6 2.4 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

Percent distribution 

55.4 38.3 6.3 

85.8 13.1 1.1 

87.4 11 .o 1.6 

75.9 22.9 1.2 

65.1 34.1 0.8 

39.8 52.0 8.2 

76.1 22.0 1.9 

53.4 40.7 5.9 

909 9.0 0.1 

878 11 .o 1.2 

82.6 16.5 0.9 

69.7 30.1 0.2 

40.6 51 .l 8.3 

70.8 26.5 2.7 

57.0 36.4 

82.0 16.2 

87.0 11.1 

70.8 27.9 

61.7 37.1 

39.4 52.4 

6.6 

1.8 

1.9 

1.3 

lFrom Medical History questionnaire-percent of total population wearing glasses and having no trouble seeing with them. 

91 
Table 38. Percent of total population age 6-74 years who wear glasses and have no trouble seeing with them and percent distribution of 

their maximum visual acuity levels in the better eye,’ by age and sex: United States, 1971-1972 

Age and sex 

Both sexes 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

6-11 years ................................................................................................................. 10.2 

12-I 7 years ................................................................................................. .............. 27.9 

1844 years ............................................................................................................... 38.5 

45-54 years ............................................................................................................... 76.6 

55-64 years ............................................................................................................... 81.4 

65-74 years ............................................................................................................... 77.9 

Male 

All ages, 6-74 years ........................................................................................ 41.5 

6-11 years ................................................................................................................. 8.8 

12-17 years ............................................................................................................... 22.9 

1844 years ............................................................................................................... 33.5 

45-54 years ............................................................................................................... 73.7 

55-64 years ............................................................................................................... 81.3 

65-74 years ............................................................................................................... 77.8 

Female 

Percent 

of total 

copulation* 

45.7 I 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

48.5 

85.2 

85.2 

81.9 

65.5 

36.3 

24.3 

-. 

39.5 

14.8 

14.4 

17.3 

34.3 

57.7 

49.6 70.3 27.7 

11.6 100.0 53.4 44.4 

32.9 100.0 77.5 21.6 

43.1 100.0 83.9 14.7 

79.3 100.0 69.7 28.9 

81.3 100.0 58.4 40.0 

78.0 100.0 36.9 56.6 

II Maximum visual acuity 

III 

Percent distribution 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

72.0 

- 

51 .I 

81.2 

84.5 

75.2 

61.7 

36.7 

74.2 

26.2 1.8 

42.1 6.8 

18.3 0.5 

14.5 1 .o 

23.7 1.1 

37.3 1 .o 

56.9 6.4 

1.5 

12.0 

0.4 

0.8 

0.2 

6.0 

All ages, 6-74 years 2.0 .,...,.,....... . ,.............,..... a... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a* .. . . . . I 

6-11 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~............................. 

12-17 years ..a . . . . . . . . . . ...*....* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ., .. . . . . . . . . . . . . . . . . . . . . . . . . . . 

18-44 years ..,.........,....................,,.......,......................................~............................, 

45-54 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

55-64 years ,,,.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . *...a . . . . . . 

65-74 years . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . ,, .. . . . . . . . . . . . . . . . . . . . . . . . . . . 

2.2 

1 .o 

1.4 

1.4 

1.6 

6.6 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on spherical 

refraction or retinoscopy for the remainder. 

*From Medical Hisotry questionnaire-percent of total population wearing glasses and having no trouble seeing with them.’ 

92 
Table 39. Percent of total population age 6-74 years who do not wear glasses and percent distribution of their usual visual acuity levels 

in the better eye, by age and sex: United States, 1971-1972 

Age and sex 

Both saxes Percent distribution 

All ages, 6-74 years.. ................................................................................. 47.9 100.0 77.0 19.5 

6-11 years ................................................................................................................. 88.2 

12-17 years.. ............................................................................................................. 69.9 

1844 years.. ............................................................................................................. 56.1 

45-54 years.. ............................................................................................................. 13.8 

6564 years ............................................................................................................... 6.9 

65-74 years ............................................................................................................... 5.9 

74.7 22.0 3.3 

82.6 14.1 3.3 

85.2 13.3 1.5 

68.0 26.9 5.1 

41 .I 49.6 9.3 

16.3 57.5 26.2 

Male 

All ages, 6-74 years.. ...................................................................................... 

6-11 years.. ............................................................................................................... 

12-17 years ............................................................................................................... 

18-44 years.. ............................................................................................................. 

45-54 years ............................................................................................................... 

55-64 years ............................................................................................................... 

65-74 years ............................................................................................................... 

53.6 78.4 18.3 3.3 

90.1 

75.5 

62.6 

18.1 

9.6 

9.5 

76.7 19.6 3.7 

85.7 11.4 2.9 

86.4 12.3 1.3 

72.5 23.6 3.9 

40.4 50.7 8.9 

18.6 60.8 20.6 

Female 

All ages, 6-74 years.. ...................................................................................... 42.5 75.4 20.8 3.8 

6-I 1 years ................................................................................................................. 

12-I 7 years ............................................................................................................... 

18-44 years ............................................................................................................... 

45-64 years.. ............................................................................................................. 

5564 years ............................................................................................................... 

65-74 years.. ............................................................................................................. 

86.3 

64.2 

50.2 

9.8 

100.0 72.7 24.5 2.8 

100.0 79.1 17.1 3.8 

106.0 84.0 14.3 1.7 

100.0 62.6 30.8 6.6 

100.0 42.1 48.0 9.9 

100.0 12.6 51.8 35.6 

‘From Medical History questionnaire. 

Percent 

of total 

population1 

Usual visual acuity 

3.5 

93 
Table 40. Percent of total population age 6-74 years who do not wear glasses and percent distribution of their maximum visual acuity 

levels in the better eye,l by age and sex: United States, 1971-1972 

Age and sex 

Both sexes 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~........................ 

6-1 1 years.. ............................................................................................................... 88.2 

12-17 years ................................................................................................................ 69.9 

18-44 years.. ..................................................................................... ....................... 56.1 

45-54 years.. ............................................................................................................. 13.8 

5564 years.. ............................................................................................................. 6.9 

65-74 years.. .............................................................................................................. 5.9 

Male 

All ages, 6-74 years.. ...................................................................................... 53.6 

6-11 years.. ............................................................................................................... 90.1 

12-I 7 years.. ............................................................................................................. 75.5 

1844 years.. ............................................................................................................. 62.6 

45-54 years.. ............................................................................................................. 18.1 

5564 years.. ............................................................................................................. 9.6 

65-74 years.. ............................................................................................................. 9.5 

Female 

All ages, 6-74 years.. ...................................................................................... 

6-11 years ............................................................................. . ................................... 

12-17 years.. ............................................................................................................. 

18-44 years.. ............................................................................................................. 

45-54 years ............................................................................................................... 

55-64 years.. ................................................................................... . ......................... 

65-74 years.. ............................................................................................................. 

42.5 

86.3 100.0 73.7 25.8 0.5 

64.2 100.0 80.7 17.7 1.6 

50.2 100.0 84.8 14.5 0.7 

9.8 100.0 63.7 32.9 3.4 

4.6 100.0 45.9 46.1 8.0 

3.2 100.0 15.7 66.8 17.5 

- t 1 

I 

Percent of 

otal popula 

tion who da 

not wear 

glasses* 

- 

i 

Total I= 

Percent distribution 

47.9 I 100.0 78.2 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

75.5 23.3 1.2 

84.2 15.0 0.8 

86.3 13.3 0.4 

69.4 28.4 2.2 

44.0 50.6 5.4 

18.3 69.5 12.2 

79.7 19.3 1 .o 

.- 

2.0 

0.2 

0.1 

ii:: 

8.9 

77.1 20.9 

87.2 12.6 

87.7 12.2 

74.0 24.8 

42.5 54.1 

19.8 71.3 

76.6 21.7 1.7 

20.4 

‘Visual acuity levels reached with usual correction for those testing 20/40 or better and with additional correction on sljherical 

refraction or retinoscopy for the remainder. 

‘From Medical History questionnaire. 

1.4 

94 
Table 41. Percent of total population age 6-74 years who have trouble with vision even when wearing glasses and percent distribution of 

their usual visual acuity levels in the better eye, by age and sex: United States, 1971-1972 

Age and sex 

Both sexes Percent distribution 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 100.0 36.8 

6-11 years ................................................................................................................. 1.6 

12-l 7 years.. ............................................................................................................. 2.2 

18-44 years ............................................................................................................... 5.4 

45-54 years.. ............................................................................................................. 9.6 

5564 years ............................................................................................................... 11.7 

65-74 years ............................................................................................... . ................ 16.2 

Male 

All ages, 6-74 years.. ...................................................................................... 4.9 

6-11 years ................................................................................................................. 1.1 

12-l 7 years.. ............................................................................................................. 1.6 

1844 years.. ............................................................................................................. 3.9 

45-54 years ............................................................................................................... 8.2 

55-64 years ............................................................................................................... 9.1 

65-74 years ............................................................................................................... 12.7 

Female 

All ages, 6-74 years ........................................................................................ 

6-11 years ................................................................................................................. 

12-l 7 years.. ............................................................................................................. 

18-44 years ............................................................................................................... 

45-54 years ............................................................................................................... 

5564 years ............................................................................................................... 

65-74 years ............................................................................................................... 

7.9 

2.1 100.0 54.3 42.2 3.5 

2.9 100.0 49.7 44.4 5.9 

6.7 100.0 75.1 21.9 d.0 

10.9 100.0 69.4 27.0 3.6 

14.1 100.0 48.7 41.2 19.1 

18.8 100.0 19.8 56.1 24.1 

“’ Percent 

of total 

Population1 

Total 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

Usual visual acuity 

52.5 38.9 

54.6 39.8 

75.5 22.5 

60.6 33.2 

44.7 45.0 

18.7 58.2 

8.6 

x*: 

6:2 

10.3 

23.1 

51.7 39.8 8.5 

47.9 29.7 22.4 

65.4 29.7 4.9 

76.1 23.6 0.3 

48.3 41.9 ‘9.8 

38.4 51 .o 110.6 

16.4 62.6 21.0 

56.3 35.1 8.6 

‘From Medical History questionnaire. 

95 
Table 42. Percent of total population age 6-74 years who have trouble with vision even when wearing glasses and percent distribution of 

their maximum visual acuity levels in the better eye,l by age and sex: United States, 1971-1972 

Age and sex 

Both sexes Percent distribution 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 100.0 55.7 39.7 4.6 

6-11 years.. ............................................................................................................... 1.6 

12-l 7 years ............................................................................................................... 2.2 

1844 years.. ............................................................................................................. 5.4 

45-54 years.. ............................................................................................................. 9.6 

5564 years.. ............................................................................................................. 11.7 

65-74 years.. ............................................................................................................. 16.2 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.9 

6-11 years.. ............................................................................................................... 1.1 

12-I 7 years.. ............................................................................................................. 1.6 

18-44 years.. ............................................................................................................. 3.9 

45-54 years ............................................................................................................... 8.2 

5564 years.. ............................................................................................................. 9.1 

65-74 years.. ............................................................................................................. 12.7 

Female 

All ages, 6-74 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.9 

6-11 years.. ............................................................................................................... 2.1 

12-l 7 years ............................................................................................................... 2.9 

18-44 years.. ............................................................................................................. 6.7 

45-54 years ............................................................................................................... 10.9 

56-64 years.. ............................................................................................................. 14.1 

66-74 years.. ............................................................................................................. 18.8 

Percent 

of total 

30pulation2 

Total m 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

100.0 

52.5 44.9 2.6 

55.7 41.3 3.0 

75.6 24.1 0.3 

62.1 34.7 3.2 

47.7 47.6 4.7 

19.3 65.3 15.4 

51.9 44.0 4.1 

47.8 52.2 

65.3 34.7 

76.1 23.6 

49.0 45.1 

38.4 57.8 

16.4 71.3 

0.3 

5.9 

3.8 

12.3 

58.0 37.1 4.9 

100.0 54.3 42.2 3.5 

100.0 51.2 44.4 4.4 

100.0 75.4 24.3 0.3 

100.0 71.6 27.1 1.3 

100.0 53.6 41.2 5.2 

100.0 20.7 62.3 17.0 

lVisual acuity levels reached with usual correction for those testing 20140 or better and with additional correction on spherical 

refraction or retinoscopy for the remainder. 

‘From Medical History questionnaire. 

96 
Table 43. Prwalmcr ratw for Mrcted medical history itams among population age 6-74 years with and without eya muscle imbnlanw, by age, HX, and race,with standard won: 

United States, 1871-1972 

Age, “x. a”d rati1 

100 population 

-rimI, 6.74 yaw* ................. 

All rwt, 6.11 yews.. ................ 

Whita ................................................... 

Black.. ................................................. 

All rncu, 12-17 y..r r ................ 

Whit. ................................................... 

Black ................................................... 

All races, 1844 year‘... ............. 

whit* ................................................... 

Black.. ................................................. 

All rrar, 46.64 ye.,* ................ 

White ................................................... 

Black ................................................... 

All rw%s, 56.64 y.ars.. .............. 

Whit*. .................................................. 

Black ................................................... 

All rawa, 65.74 y..,‘.. .............. 

White ................................................... 

Black ................................................... 

Total, 6.74 y..r ‘ ................. 

All racas. 641 y.arr .................. 

Whitr BIKk ................................................... 

................................................... 

All races, 12.17 yews ................ 

Whita ................................................... 

Black ................................................... 

All rims, 1644 ynrs ................ 

White. .................................................. 

Black.. ................................................. 

All racas. 46.64 yews.. .............. 

White 6,~k ................................................... 

................................................... 

All rams, 66.64 YH~S.. .............. 

White ................................................... 

Slack ................................................... 

All new, 66.74 ~.a,,. ............... 

whita ................................................... 

Black.. ................................................. 

- 

No eys muscle imbalance Eye muscle imbalmcs 

Doar (did) Door (did) 

have have 

EVM trouble Visited Visited 

have seeing doctor Ever troubls 

ha- saeinp doctor 

trouble we” when about trouble even when about 

seeing wmring trouble 

seeing Maing &earing trouble 

glasses OI glasses or 

seeing 

contacts COntlctI 

Standard error 

‘Totals include races other than whim and Black. 

97 
Table 43. Prevalence rates for selected medical history items among population age 5-74 wars with and without we muscle imbalance. bv a!asex. and race. with standard errors: 

United States, 1971.197%Con. 

- 

No eye muscle imbalance 

EVH 

have 

trouble 

seeing 

Does (did) 

have 

trouble 

seeing 

eve” when 

wearing 

glsues or 

CO”,WtS 

Visited 

doctor 

about 

trouble 

seeing 

Eye muscle imbalance No eye muscle imbalance Eye muscle imbalance 

--r 1 q ‘oes ldidl 1 

haA 

EVer trouble Visited 

have seeing doctor 

trouble even when about 

seeing wearing trouble 

glasses or 

seeing 

Doss (did) 

have 

trouble 

seeing 

we” when 

wearing 

glasses or 

CO”tXtS 

Does (did) 

have 

trouble 

seeing 

eve” when 

wearing 

glasses or 

CO”tWtS 

Visited 

doctor 

about 

trouble 

Evw 

have 

troubls 

Visited 

doctor Ever 

about have 

trouble trout 

seeing seek 

Age, sex, and race1 

I cc.ntacts I 

, I 

Female Rate Per 100 population Standard error 

Total, 5-74 years ................. 

All races. 5.11 years.. ................ 88.4 19.9 

White.. ................................................. 

Black ................................................... 

18.5 15.0 -I- 18.3 14.5 

19.7 28.8 

89.2 20.5 8.4 100.0 

74.4 15.0 25.7 loo.0 

All races. 12-l 7 years.. .............. 78.0 52.7 17.2 89.2 

White.. ................................................. 

Black ................................................... 

43.3 8.4 

-t 

45.3 8.3 

27.1 9.1 

77.5 

82.2 

All races, 1844 years.. .............. 55.8 1 10.8 91.8 

White ................................................... 

Black ................................................... 

92.5 51.3 14.9 93.5 2.20 1.23 

85.8 50.3 5.0 82.1 2.85 2.89 

All races, 45.54 years ............... 

White. Black .................................................. 

................................................... 

95.3 85.7 10.9 93.9 2.47 2.51 

97.1 87.4 9.5 95.3 2.40 3.35 

91.5 79.1 30.3 77.1 5.85 8.33 

All races, 55-54 years.. .............. 99.5 

White.. ................................................. 

Black ................................................... 

All races, 55.74 years.. .............. 

White ................................................... 

Black ................................................... 

57.8 11.0 

40.7 8.2 

84.5 14.2 

85.1 13.9 

78.9 15.2 :I 85.8 13.8 

85.7 14.3 

87.4 8.7 

89.2 20.3 

90.3 20.4 

78.2 20.2 

99.7 

97.4 

99.0 

99.5 89.8 

93.4 80.4 

55.7 15.7 

:- 

9.9 

94.3 1.38 

- 

1.94 

1.90 

5.94 

3.29 

0.94 1 A3 

- 

22.35 

3.78 

100.0 5.14 

7.M 

24.30 

2.95 

53.9 

47.7 

59.4 

20.9 

14.3 

87.4 3.53 

98.5 8.58 

92.3 1.85 

3.05 

5.51 

1.14 

8.03 

1.50 

4.59 

1.54 

2.87 

1.90 

3.42 

2.37 

11.21 

3.00 

1 A5 4.05 

1.92 2.98 

1.71 4.58 

94.5 

94.5 

89.4 

88.9 

19.2 

.- 

19.9 

25.3 

24.5 

.- 

24.0 

. 30.8 

97.5 3.97 2.79 

97.3 4.34 2.95 

100.0 2.77 5.19 

99.8 1.51 2.08 

99.9 1.57 2.29 

98.7 3.58 3.75 

3.04 

22.13 

2.55 

2.71 

0.23 

4.89 

21.45 

4.35 

13.09 

0.15 

2.21 

l~otals include races other than white and Black. 

98 
Table 44. Prevalence rates for medical history findings pertaining to the eye among population age 6-74 years, by age, sex, race, and geographic region, 

with standard errors: United States, 1971-1972 

Selectad medical history findings, 

geographic region, and sex 

Both sexes 

Ever have trouble seeing: 

Northeast ............................... . .......................... 

Midwest ............................................................. 

South ...... . ......................................................... 

West .................................................................. 

Visited doctor about trouble seeing: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West ......................................................... .:. ...... 

Ever wear glasses or contact tense:: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West .................................................................. 

Male 

- 

Ever have trouble seeing: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West .................................................................. 

Visited doctor about trouble seeing: 

Northeast .......................................................... 

Midwest.. ........................................................... 

South ................................................................ 

West .................................................................. 

Ever wear glasses or contact lenses: 

Northeast .......................................................... 

Midwest.. ........................................................... 

South ................................................................ 

West .................................................................. 

Female 

Ever have trouble seeing: 

Northeest .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West .................................................................. 

Visited doctor about trouble seeing: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

west .................................................................. 

Ever weer glasses or contti lenses: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

Wert .................................................................. 

‘Totals include reces other then white and Black. 

Age in years 6-74 years 

6-l 1 12-17 16-24 2634 3544 46-54 5564 65-74 All 

races1 

White Black 

Rate per 100 population 

20.0 44.4 56.2 50.3 54.5 799 65.0 67.4 57.: 57.7 528 

16.2 46.6 53.6 53.6 53.6 639 61.7 65.6 56.7 57.9 44.2 

12.9 358 43.4 45.5 60.1 65.3 66.5 90.4 55.E 69.4 40.4 

138 37.0 468 52.6 518 61.6 88.1 63.3 54.c 55.2 40.4 

96.0 69.9 97.0 95.6 91.0 95.6 96.9 97.3 95.c 95.4 91 .l 

69.6 67.7 95.2 95.5 90.9 96.9 99.3 96.3 94.5 95.0 94.4 

65.6 65.6 91 A 89.7 91.7 69.6 96.4 97.1 92.c 94.2 79.6 

94.6 69.6 60.0 90.4 92.5 96.3 98.3 96.0 93.5 94.2 87.6 

16.9 40.0 59.4 53.5 59.4 91.5 96.0 97.9 61.f 62.3 54.6 

16.1 42.0 59.6 57.6 60.0 90.2 95.6 97.7 60.6 62.3 47.4 

6.9 32.1 43.0 47.5 59.7 65.3 92.3 95.7 55.E 60.5 36.7 

11.3 32.0 51.5 57.0 56.4 698 95.4 95.6 57.; 58.6 39.3 

23.9 41.6 50.6 46.2 47.2 76.6 80.7 66.4 53.1 53.6 45.2 

16.3 36.9 43.5 46.6 41.6 61.6 79.2 80.3 50.1 51.5 34.7 

6.6 31.6 34.0 39.6 56.6 84.7 64.5 90.3 49.7 54.0 33.4 

128 26.0 44.7 46.5 47.5 76.7 64.5 77.6 49.0 49.9 34.6 

100.0 92.6 96.1 92.6 92.6 94.6 

64.5 90.2 94.5 96.3 92.1 97.1 

74.1 66.9 66.4 90.2 92.3 66.1 

88.7 91.2 69.3 64.6 90.6 96.7 

94.4 

97.6 

95.4 

96.5 

94.3 

95.6 

90.7 

92.3 

Ei 

93.2 

93.4 

69.0 

96.6 

758 

79.4 

17.2 36.2 50.3 42.6 50.4 65.2 

16.6 33.4 50.7 51 .o 50.6 66.0 

7.5 26.2 269 42.3 54.5 79.6 

7.3 23.0 43.7 46.5 46.6 88.2 

92.6 

93.6 

::: 

96.4 54.4 55.4 419 

95.9 55.5 56.9 40.1 

92.2 46.6 54.0 26.0 

92.4 51.0 52.0 269 

16.2 47.6 61 .B 544 61.5 62.5 88.4 66.1 61.3 61.6 59.2 

19.9 57.3 64.9 60.2 64.3 66.3 B4.3 69.3 63.2 64.4 52.2 

20.1 39.6 51.5 50.7 61.4 66.6 92.1 90.5 60.7 64.3 46.7 

14.7 47.1 52.1 56.0 56.0 64.6 91.3 67.9 566 60.0 44.7 

918 67.2 97.7 98.6 69.6 96.6 9B.4 

65.7 66.0 95.7 95.0 99.1 96.7 99.6 

91.7 64.6 94.2 89.3 91.3 90.7 96.0 

loo.0 668 90.5 94.6 93.9 66.0 98.4 

ii:: 

96.4 

96.0 

95.6 96.0 92.4 

94.3 94.4 92.6 

93.0 95.0 62.1 

94.7 94.6 93.3 

20.7 42.1 68.6 64.1 

15.6 51 .l 69.1 63.9 

10.5 36.2 55.2 52.2 

15.1 40.3 56.0 64.3 

68.1 

::I: 

64.0 

96.7 96.6 99.1 

92.7 96.1 96.0 

69.6 94.9 96.2 

91.3 97.1 96.2 

66.5 66.9 65.1 

678 53.6 

66.3 44.5 

64.6 46.6 

99 
Table 44. Prevalence rates for medical history findings pertaining to the eye among population age 6-74 years, by age, sex, race, and geographio region, 

with standard errors: United States, 1971-1972-Con. 

Selected medical history findings, 

geographic region, and sex 

Both sexes 

Ever have trouble seeing: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West .................................................................. 

Visited doctor about trouble seeing: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West .................................................................. 

Ever wear glasses or contact lenses: 

Northeast.. ........................................................ 

Midwest.. ............................... . ........................... 

South ................................................................ 

West .................................................................. 

Male 

- 

Ever have trouble seeing: 

Northeast .......................................................... 

Midwest.. ........................................................... 

South ................................................................ 

west .................................................................. 

Visited doctor about trouble seeing: 

Northeast .......................................................... 

Midwest.. ........................................................... 

South ................................................................ 

West .................................................................. 

Ever wear glasses or contact lenses: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West .................................................................. 

Female 

Ever have trouble seeing: 

Northeast .......................................................... 

Midwest.. ........................................................... 

South ................................................................ 

West .................................................................. 

Visited doctor about trouble seeing: 

Northeast .......................................................... 

Midwest ............................................................. 

South ................................................................ 

West .................................................................. 

Ever wear glasses or contact lenses: 

Northeast .......................................................... 

Midwest.. ........................................................... 

South ................................................................ 

West .................................................................. 

‘Totals include races other than white and Black. 

Age in years I 6-74 years 

6-11 1 12-17 j 16-24 1 2534 1 3544 1 45-64 1 5564 1 65-74 

2.15 3.00 3.60 3.29 2.40 1.36 3.13 1.53 1.04 1.11 3.97 

1.67 2.91 3.104 2.93 2.06 2.60 4.01 3.41 1.64 1.95 3.51 

2.30 3.53 2.75 3.31 2.76 2.16 2.10 1.22 1.31 1.32 1.72 

1.61 2.64 2.62 1.96 1.76 1 a2 2.63 1.04 1 .OB 1.09 3.70 

3.62 2.20 106 1.43 2.25 1.14 1.33 0.62 0.41 0.51 2.60 

4.76 2.29 1 JD7 1.26 la3 1 A6 0.56 0.47 0.66 0.75 1.60 

7.33 1.05 2.102 2.17 2.43 1.54 1 .Ol 0.56 0.73 0.96 2.05 

4.70 2.95 3.15 3.03 1.55 1.68 1.06 0.77 1.16 1 .lB 3.02 

2.16 3.09 220 2.23 2.74 1 A0 0.66 0.72 0.99 1.06 4.13 

1.04 2.95 2.07 2.54 2.34 1.72 1.46 0.66 089 1.05 3.29 

1.51 2.64 2JB6 2.42 2.29 1.97 2.05 0.46 1.26 1.25 1.59 

1.39 2.76 281 2.72 2.39 1.74 1.96 1.00 1.52 1.47 3.14 

2.63 4.11 6.~45 4.65 5.35 2.76 3.61 1.65 1.22 1.38 3.64 

3.04 3.14 4.01 4.92 2.75 3.54 4.77 4.56 2.21 2.36 6.09 

1.13 3.56 4.15 785 6.73 1.76 3.04 1.41 2.60 2.75 2.65 

2.12 2.64 4129 4.62 5.65 2.27 3.16 2.68 1.06 1.36 5.71 

6.59 

17.51 

10.20 

2.95 2.16 3.32 3.30 2.23 2.91 ia 0.61 0.66 6.07 

4.05 2.iBB 186 3.65 1.27 1.14 086 0.63 0.56 090 

2.66 5.:26 4.73 3.30 2.95 1.64 1.03 0.96 1.06 3.50 

4.72 5 .:30 7.01 3.21 2.16 1.68 1.60 1.63 1.62 5.75 

3.10 3.82 5.14 2.91 5.11 286 1.76 1.32 1.27 1.45 6.25 

1.62 3.83 3.67 4.47 2.62 3.10 2.65 1.25 0.90 1.14 4.60 

1.40 384 5.02 5.64 4.36 3.65 4.15 0.91 2.05 2.17 2.56 

2.60 2.63 4x9 3.66 5.74 3.02 3.47 1.97 1.67 1.69 5.64 

4.11 5.17 3.‘47 3.54 2.75 2.62 4.02 1.99 1.44 1.61 5.76 

2.39 2.65 3.iD6 2.61 2.66 3.06 5.22 3.06 1.62 1.64 4.31 

3.74 6.16 3.163 1.62 2.51 4.03 3.22 1.16 1.60 1.51 2.96 

3.70 4.26 3.106 2.77 2.79 3.71 2.71 2.04 1.60 1.46 3.76 

7.22 

6.39 

6.60 

3.79 1.15 0.51 2.24 1.59 1.32 0.23 0.72 0.70 1.76 

1.69 1.16 1.37 2.11 1 .BB 0.26 0.79 0.95 1.04 2.51 

2.70 1 .I06 2.42 2.34 2.16 1.03 0.54 0.66 1.21 2.62 

4.54 2.40 2.56 1.51 2.11 1.24 0.53 1.16 1.24 2.94 

3.07 4.29 2.16 3.59 3.26 1.14 1.16 0.56 1.47 1.43 4.27 

1.57 3.14 2.86 3.31 2.74 2.16 1.32 0.71 1.45 1.54 3.94 

2.33 4.67 3.02 2.37 3.07 2.59 2.99 0.37 1.63 1.46 2.22 

3.16 4.62 3.:25 2.64 2.09 3.27 1.26 0.49 1.61 1.59 5.14 

All 

races1 II I 

White Black 

100 
Table 45. Percent distribution of lenses in the glasses or contact lenses of youths age 12-17 years, by the spherical or cylindrical power 

of the lens: United States, 1966-1970 and 1971-1972 

Spherical or cylindrical power of lens (in diopters) 

Total tested ...................................................................................................................... 100.0 100.0 100.0 

Minus 

5.1 D or more ................................................................................................................................... 6.4 6.4 6.6 

4.1-5.0 cl .......................................................................................................................................... 5.6 6.2 6.0 

3.1-4.0 D .......................................................................................................................................... 9.4 14.6 10.4 

2.1-3.0 D .......................................................................................................................................... 16.7 16.0 15.6 

1.6-2.0 D .......................................................................................................................................... 11.2 11.2 10.6 

1.1-1.5 D .......................................................................................................................................... 11.7 15.8 11.8 

0.6-I .O D .......................................................................................................................................... 10.6 10.5 11.6 

0.1-0.5 D .......................................................................................................................................... 8.4 6.4 10.4 

0.0 D ................................................................................................................................................ 

Plus - 

0.1-0.5 D .......................................................................................................................................... 

0.6-l .O D .......................................................................................................................................... 

1 .l-2.0 D .......................................................................................................................................... 

2.1 D or more ................................................................................................................................... 

4.0 2.7 3.2 43.2 

6.3 3.0 58 13.8 

3.0 0.8 2.8 9.2 

2.8 2.2 2.2 4.0 

3.7 4.2 3.0 1.4 

Percent distribution of 

lenses tested 

100.0 

0.3 

0.8 

0.4 

3.6 

6.6 

16.7 

Table 46. Percent distribution of lenses in the glasses or contact lenses of youths age 12-17 years, by the degree of axis deviation of the 

cylinder in the lens: United States, 1966-1970 and 1971-1972 

Axis deviation (in degrees) 1966-l 970 1971-1972 

Percent distribution of 

lenses tested 

Total tested . . . . . . . , . . , . , . . . . . . , . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100.0 1 100.0 

b 

None ............................................................................................................................................................. 

1°-450 ........................................................................................................................................................... 

460 90” ......................................................................................................................................................... 

91a-1350 ....................................................................................................................................................... 

136” -180’ ..................................................................................................................................................... 

101 
Table 47. Percent distribution of lenses in the glasses and contact lenses of youths age 12-17 years, by the power and equivalence of the 

lens: United States, ‘1966-1970 and 1971-1972 

Power or equivalence (in diopten) 

Total tested ...................................................................................................................... 100.0 

Minus 

-- 

7.6 D or more ................................................................................................................................... 15.0 

5.1-7.5 D .......................................................................................................................................... 15.1 

4.1-5.0 D .......................................................................................................................................... 8.3 

3.14.0 D .......................................................................................................................................... 11.3 

2.13.0 D .......................................................................................................................................... 12.0 

1.6-2.0 D .......................................................................................................................................... 6.4 

1.1-1.5 D .......................................................................................................................................... 4.6 

0.6-I .O D .......................................................................................................................................... 6.3 

0.1-0.5 D .......................................................................................................................................... 3.5 

0.0 D ................................................................................................................................................ 

Plus 

2.1 

2.9 

3.7 

3.4 

5.4 

0.1-0.5 D ....................................................................................... ................................................... 

0.6-l .O D .......................................................................................................................................... 

1.1-2.0 D .......................................................................................................................................... 

2.1 D or more .................................................................................................................................... 

Percent distribution of 

lenses tested 

100.0 100.0 100.0 

1.9 

5:: 

13.9 

17.8 

11.3 

11.5 

12.1 

5.4 

7.0 1.9 

13.0 5.1 

9.0 5.2 

10.4 15.0 

15.5 18.2 

7.8 11.1 

8.6 13.0 

7.4 11.2 

4.0 6.4 

3.2 1.2 2.2 

3.4 

9:: 

4.6 

3.8 2.4 

4.2 1.4 

2.1 2.4 

6.0 45 

102 
APPENDIXES 

I. 

II. 

IIL 

Iv. 

I. 

II. 

III. 

Iv. 

V. 

VI. 

VII. 

VIII. 

CONTENTS 

Statistical Notes ........................................................................................................................... 

The Survey Design ..................................................................................................................... 

Nonresponse .............................................................................................................................. 

Missing Data .............................................................................................................................. 

Sampling and Measurement Error ...................................... ..” .................................................... 

Reliability of Measurements ...................................................................................................... 

Bias and Precision of Estimates From Medical History Responses ............................................. 

Demographic and Socioeconomic Terms ..................................................................................... 

Eye Condition Definitions ........................................................................................................... 

Recording and History Forms ...................................................................................................... 

Visual Acuity ............................................................................................................................ 

Motility ..................................................................................................................................... 

Refraction-Nutrition Exam . ..” .................................................................................................. 

Refraction-Detailed Exam ......................................................................................................... 

Selected Items From Medical History Questionnaire, Ages 6-11 ................................................ 

Selected Items From Medical History Questionuaire, Ages 12-74 .............................................. 

LIST OF APPENDIX TABLES 

Percent distribution of nonresponse adjustment factors: Health and Nutrition Examination 

Survey (HANES I), stands l-35,1971-1972 ............. ..“............~ ............................................... 

Number of examinees, number and percent of e xaminees not tested, and extent of 

visual acuity tests imputed, by age: Health and Nutrition Examination Survey 

(HANES I), 1971-1972 ............................................................................................. ..” .......... 

Number of examinea, number wearing glasses or contact lenses, and number of pracrlptions 

not determined, by age: Health and Nutrition E x&nation Survey (I-LANES I), 1971-1972 ..... 

Examiner-observer agreement in motility condition identification on 230 replicate 

examinations: Health and Nutrition E xamination Survey (HANES I), 1971-1972.. .................. 

Frequency and percent distribution of absolute differences between examhmr and observer 

determinations of spherical and cylindrical power in lens for each eye: Health and Nutrition 

Examination Survey (I-LANES I), 1971-1972 ................. .._............” .......................................... 

Frequency and percent distribution of absolute differences between examiner and observer 

determinations of axis of deviation in lens for each eye: Health and Nutrition Examination 

Survey (HANES I), 1971-1972 ........................ ..-...................................” ................................. 

Precision of sdected medical hiitory estimates for the 65ttand sample and the &stand 

subsample, by sex: United States, 1971-1972 and 1971-1974 ................................................... 

Prevalence rates for selected medical history items pert&kg to the eye, and percent 

distribution by age lenses first worn, among population 6-74 years, by age and sex: United 

states, 1971-1972 ..................................................................................................................... 

VIIIA. Standard errors for prevalence rates for selected medical bistory items pertaining to the eye, 

and percent distribution by age lenses first worn, among population 6-74 years, by age and 

sex: United States, 1971-1972 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

104 

104 

105 

107 

SO8 

108 

109 

111 

117 

i19 

121 

121 

121 

122 

122 

123 

124 

107 

107 

108 

109 

110 

111 

112 

113 

115 

103 
APPENDIX I 

STATISTICAL NOTES 

The Survey Design 

The sampling plan for the first 65 stands of 

the Health and Nutrition Examination Survey 

(HANES) followed a stratified, multistage probability design in which a sample of the civilian 

noninstitutionalized population, 1-74 years of 

age, of the coterminous United States, was 

selected. Excluded from the selection were 

persons residing in Alaska and Hawaii and those 

within the coterminous United States who were 

confined to institutions or residing on reservation lands of American Indians. Successive elements dealt with in the process of sampling were 

the primary sampling unit (PSU), census enumeration district (ED), segment (a cluster of 

households), household, eligible persons, and, 

finally, the sample person. 

The starting points in the first stage of this 

design were the 1960 decennial census lists of 

addresses and the nearly 1,900 PSU’s into which 

the entire United States was divided. Each PSU 

is either a standard metropolitan statistical area 

(=@A), a single county, or two or three 

contiguous counties. The PSU’s were grouped 

into 357 strata for use in the Health Interview 

Survey and subsequently collapsed into 40 

superstrata for use in Cycles II and III of the 

Health Examination Survey and the Health and 

Nutrition Examination Survey. 

Of the 40 superstrata, 15 contained a single 

large metropolitan area of more than 2 million 

population. These 15 large metropolitan areas 

were selected for the sample with certainty. The 

25 noncertainty strata were classified into 4 

broad geographic regions of approximately equal 

population and cross-classified into 4 broad 

population density groups in each region. Then a 

modified Goodman-Kish controlled selection 

technique was used to select 2 PSU’s from each 

of the 25 noncertainty superstrata with the 

probability of selection of a PSU proportionate 

to its 1960 population so that proportionate 

representation of specified State groups and rate 

of population change classes was maintained in 

the sample. In this manner a total first:’ stage 

sample of 65 PSU’s was selected. These 65 

sample PSU’s or stands are the areas within 

which samples of persons would be selected for 

examination over a S-year survey period. 

In order to produce national estimates of the 

nutritional status of the U.S. population at an 

earlier date, a probability subsample of 35 

stands of the 65 stands was selected. This 

35-stand subsample also made it possible to 

produce national estimates of certain other 

aspects of health status in the population that 

were critically needed at an earlier date and 

examination components that. for logistic reasons could not be continued for the remainder 

of the 65 stands. Included among the 35 stands 

were 10 of the 15 large “certainty” metropolitan areas and 1 stand from each of the 25 

“noncertainty” superstrata. The reduction from 

15 to 10 large metropolitan areas was accomplished by randomly selecting one stand from 

multiple-stand standard metropolitan statistical 

areas (SMSA’s); e.g., selecting the southern half 

of the Chicago SMSA to represent the entire 

SMSA. (This selection procedure was based on 

operational considerations, and although unbiased, is recognized as not being statistically 

optimal.) It is this subsample of 35 stands’upon 

which the findings contained in this report are 

based. 

Although the 1970 census data were used as 

the frame for selecting the sample within PSU’s 

when they became available, the calendar of 

104 
operations required that 1960 census data be 

used for the 35-stand sample of HANES. Census 

enumeration districts in each PSU were divided 

into segments of an expected six housing units 

each. In urban ED’s, the segments were clusters 

of six addresses from the 1960 census listing 

books. For ED’s not having usable addresses, 

area sampling was employed, and consequently 

some variation in the segment size occurred. To 

make the sample representative of the thencurrent population of the United States, the 

address or list segments were supplemented by a 

sample of housing units that had been constructed since 1960. 

Within each PSU a systematic sample of 

segments was selected. The ED’s that fell into 

the sample were coded into one of two economic classes. The first class, identified as the 

“poverty stratum,” was composed of “current 

poverty areas” that had been identified by the 

U.S. Bureau of the Census in 1970 (pre-1970 

census), plus other ED’s in the PSU with a mean 

annual income of less than $3,000 in 1959 

(based on 1960 census). The second economic 

class, the “nonpoverty stratum,” included all 

ED’s not designated as belonging to the poverty 

stratum. 

All sample segments classified as being in the 

poverty stratum were retained in the sample. 

For those sample segments in nonpovertystratum ED’s, the selected segments were 

divided into eight random subgroups, and one of 

the subgroups was chosen to rem-&r in the 

HANES sample. This procedure permitted a 

separate analysis with adequate reliability of 

those classified as being below the poverty level 

and those classified as being above the poverty 

level. 

After identification of the sample segments, 

a list of all current addresses within the segment 

boundaries was made, and the households were 

interviewed to determine the age and sex of each 

household member, as well as other demographic and socioeconomic information required 

for the survey. 

To select the persons in sample segments to 

be examined in the Health and Nutrition Examination Survey, all household members age l-74 

in each segment were listed on a sample selection worksheet with each household in the 

segment listed serially. The number of household members in each of the six age-sex groups 

shown below was listed on the worksheet under 

the appropriate age-sex-group column. The sample selection worksheets were then put in 

segment number order and a systematic random 

sample of persons in each age-sex group was 

selected to be examined using the following 

sample rates: 

Age in years R&l? 

1-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 

6-I 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l/4 

20-44, males . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 

2044, females . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l/2 

45-64 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l/4 

65-74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 

The persons selected in the 35-stand sample 

of the Health and Nutrition Examination Survey 

comprised a representative sample of the target 

population and included 14,147 sample persons 

1-74 years of age, of whom 10,126, or 71.6 

percent, were examined. When adjustments are 

made for differential sampling for high-risk 

groups, the response rate becomes 72.8 percent. 

All data presented in this report are based on 

weighted observations; that is, data recorded for 

each sample person are inflated to characterize 

the subuniverse from which that sample person 

was drawn. The weight for each examined 

person is a product of the reciprocal of the 

probability of selecting the person, an adjustment for nonresponse cases (i.e., persons not 

examined), and a poststratified ratio adjustment 

that increases precision by bringing survey results into closer alignment with known U.S. 

population figures. 

A more detailed description of the survey 

design and selection technique can be found in 

the “Plan and Operation of a Health and Nutrition Examination Survey, United States, 1971- 

1973,” Vital and Health Statistics, Series 1, No. 

10a.6 

Nonresponse 

In any health examination survey, after the 

sample is identified and the sample persons are 

NOTE: A list of references follows the text. 

105 
requested to participate in the examination, the 

survey meets one of its more severe problems. 

Usually a sizable number of sample persons will 

not participate in the examination. Whether or 

not an individual participates is determined by 

many factors, some of which are uncontrollable 

and, therefore, may be reasonably treated as an 

outcome of a random event with a particular 

probability of occurrence. If these probabilities 

of participation were known and greater than 

zero for all persons, then the examined persons 

would constitute a probability sample from 

which unbiased estimates of the target population could be derived. In this situation, the 

effect of nonparticipation would only be to 

reduce the sample size, thereby increasing the 

sampling errors of examination findings. However, in practice, a potential for bias due to 

nonresponse exists, since the exact probabilities 

are never known. A further potential for bias 

exists if a sizable proportion of sample persons 

have a zero probability of participation, that is, 

they would never agree to participate in an 

examination survey of the same procedures and 

inducements, and if these persons differ from 

other sample persons with respect to characteristics under examination. It is for these reasons 

that intensive efforts are made in the Health and 

Nutrition Examination Survey to develop and 

implement procedures and inducements that 

would reduce the number of nonrespondents 

and thereby reduce the potential of bias due to 

nonresponse. These procedures and inducements 

are discussed in the “Plan and Operation of the 

Health and Nutrition Examination Survey,” 

Series 1, No. lOa. 

Despite these intensive efforts, 27.2 percent 

of the sample persons from the first 35 stands 

were not examined. Consequently, the potential 

for a sizable bias does exist in the estimates in 

this publication. From what is known about the 

nonrespondents and the nature of nonresponse, 

it is believed that the likelihood of sizable bias is 

small. For instance, only a small proportion of 

persons gave reasons for nonparticipation which 

would lead to the belief that they would never 

agree to participate in examination surveys and 

that they may differ from examined persons 

with respect to the characteristic under examination. Only 15 percent of the nonrespondents 

gave-as their reasons for nonparticipation “personal illness,” “physically unable,” “pregnant,” 

“antidoctor,” or “fear of finding something 

wrong.” Typical among the reasons given by the 

other nonrespondents were the following: “unable because of work, school, or household 

duties”; “suspicious” or 

gram”; 

“skeptical of the pro- 

“just not interested in participating”; 

and “private medical care sufficient” or “just 

visited doctor.” 

An analysis of medical history data obtained for most nonexaminees as well as examinees also supports the belief that the likelihood of sizable b&due to nonresponse is small. 

No large differences were found between the 

examined group and nonexamined group for the 

statistics compared. For example, 11 percent of 

persons examined reported having an illness or 

condition that interfered with their catting as 

compared with 9 percent of persons who were 

not examined but who had completed a medical 

history. The percent of persons examined who 

reported ever being told by a doctor that they 

had arthritis was 20 percent; the percent for 

high blood pressure was 18 percent and for 

diabetes was 4 percent. The corresponding percents for nonexamined persons were 17 percent 

for arthritis, 21 percent for high blood pressure, 

and 4 percent for diabetes. 

As mentioned earlier, the data in this report 

are based on weighted observations, and one of 

the components of the weight assigned to an 

examined person was an adjustment for nonresponse. Since the probabilities of participation 

are not known for sample persons in the Health 

and Nutrition Examination Survey, a procedure 

was adopted which multiplies the reciprrocal of 

the probability of selection of sample persons by 

a factor that brings estimates based only on 

examined persons up to a level that would have 

been achieved if all sample persons had been 

examined. This nonresponse adjustment factor is 

the ratio of the sum of sampling weights for all 

sample persons within a relatively homogeneous 

class defined by age, sex, and poverty status to 

the sum of sampling weights for all resp’onding 

sample persons within the same homogeneous 

class. To the degree that homogeneous groups 

that are also homogeneous with respect to the 

characteristics under study can be defined, the 

106 
Table I. Percent distribution of nonresponse adjustment factors: 

Health and Nutrition Examination Survey (HANES I), 

stands I-35,1971 -1972 

failure to obtain and record all items of information for examined persons. The extent of missing data and the rationale used for estimating 

these values in incomplete examinations of 

concern in this report are discussed below. 

Visual acuity.-The extent of missing data 

for the visual acuity testing ranged from 3 to 5 

percent for persons age 6-74 years, but among 4- 

and 5-year-olds more than one-fifth (22 percent) 

did not have visual acuity readings. The extent 

of missing data for those visual acuity tests is 

shown in table II. 

Estimates were made for the missing visual 

acuity scores as follows. For each examined 

person with some (although incomplete) record 

of visual acuity, a visually examined respondent 

of the same age, sex, race, and income group 

with relevant findings similar to those available 

for the incompletely examined person was 

selected at random; and the remainder of his test 

results were assigned to the individual with those 

missing values. 

In doing this imputation, persons whose 

examination showed an enucleated globe were 

classed as blind in that eye, and selection of 

missing data for persons with cataracts was made 

from among those with cataracts whose visual 

acuity had been determined. If visual acuity for 

one eye was available and other examination 

findings indicated no problems with the other 

Size of factor Percent 

distribution 

Total .,...................................................... 100.0 

1.00-I .24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38.4 

1.25-l .49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.6 

1.50-I .74 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.9 

1.75-I .99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 

2.00-2.49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 

2.50-2.99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 

3.00-3.03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 

procedure can be effective in reducing the 

potential bias from nonresponse. 

For the 35-stand sample of the Health and 

Nutrition Examination Survey, persons were 

grouped into 20 age-sex-poverty status groups 

within each stand, yielding 700 separate cells 

with an average membership of about 20 sample 

persons each. These adjustment factors are 

distributed among examined persons as shown in 

table I. 

Missing Data 

Examination surveys are subject to the loss 

of information not only through the failure to 

examine all sample persons, but also from the 

Table II. Number of examinees, number and percent of examinees not tested,and extent of visual acuity tests imputed, by age: Health 

and Nutrition Examination Survey (HANES I), 1971-1972 

- 

T Age in years Examinee status and 

imputed activity tests 4-74 4-5 6-11 12-17 18-24 2534 3544 45-54 5564 65.74l 

All examinees ............................. 9,263 626 I ,067 

Number not tested ...................................... 504 136 

Percent .................................................. 5.4 21.7 

Uncorrected: 

Right eye ............................................... 

Left eye.. ............................................... 

Both eyes .............................................. 

14 

11 

354 

3 

133 

47 

4.4 

1 

I 

45 

I#015 1,259 1,170 793 630 1,658 

31 49 60 27 24 83 

3.1 3.9 5.1 3.4 3.8 5.0 

2 

1 

24 

1 

41 

2 2 1 2 

2 1 1 2 

32 12 5 22 

4 

1 3 

6 21 

3 2 10 

3 3 11 

6 12 36 

15 

23 

87 

1,045 

47 

4.5 

1 

2 

40 

2 

2 

Corrected: 

Right eye.. ............................................. 

Left eye.. ............................................... 

Both eyes .............................................. 

lIncludes 8 examinees who were 74 years of age at the time of interview, but became 75 years old by the time of examination. 

107 
eye, the vision data for that eye were imputed to 

the other eye. For those examined persons 

whose visual acuity had not been recorded in 

either eye, a visually examined respondent of 

the same age, sex, race, and income group was 

selected at random, and his test results were 

assigned to the individual with missing acuity 

data. 

The assumption was made in this that the 

distribution of visual acuity values among those 

persons with missing data by age, sex, race, and 

other variables would be similar to values for 

those tested. 

Refraction.-The extent of missing refraction data was greater than that for the visual 

acuity data. For 6-74-year-olds, the prescription 

was not obtained from 6 to 19 percent of the 

subjects who wore their glasses or contacts to 

the examination center (table III). Among 4- 

and 5-year-olds, 56 percent of the data were 

missing. 

Because prevalence estimates were sought 

for right and left eye separately, data from the 

fellow eye were not used to fill in a partially 

missing record. Furthermore, due to tbe extent 

of missing data, the substitution of imputed 

values for missing data could lead to distortion 

of the national estimates. 

Although no explicit method of imputation 

was used to replace missing refraction data, the 

assumption has been made here that the distribution- of refraction values among those persons 

with missing data would be similar to the known 

values for those examined of the same age, sex, 

race, and other socioeconomic characteristics 

used in this report as analysis variables. 

Small Numbers 

In some tables, magnitudes are shodin for 

cells for which the sample size is so small that 

the sampling error may be several times as great 

as the statistic itself. Obviously in such instances 

the numbers, if shown, have been included to 

convey an impression of the overall story of the 

table. 

Sampling and Measurement Error 

In the present report, reference has been 

made to efforts to minimize bias and variability 

of measurement techniques. The potential of 

residual bias due to the high nonresponse rate 

has also been discussed. 

The probability design of the survey makes 

possible the calculation of sampling errors. 

Traditionally the role of the sampling errlor has 

Table III. Number of examinees, number wearing glasses or contact lenses, and number of prescriptions not determined, by age: Health 

and Nutrition Examination lgurvey (HANES I), 1971-1972 

Examinees and missing lens 

prescriptions 

All exeminees . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Number wearing glasses or contact lenses.... 

Prescriotion not determined 

56 

4.4 

14.0 

Right eye: 

Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361 15 ‘16 32 60 51 1 31 27 

Percent of total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9 2.4 I.5 3.1 5.9 4.4 3.9 4.3 

Percent of examinees wearing 

glasses or contact lenses . . . . . . . . . . . . . . . . . . . . . . 10.2 55.6 15.4 14.4 18.9 13.5 7.5 6.3 

Left eye: 

Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 15 16 33 60 47 18 25 

Percent of total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 2.4 1.5 3.2 5.9 4.0 2.3 4.0 

Percent of examinees wearing 

glasses or contact lenses . . . . . . . . . . . . . . . . . . . . . . . 9.2 55.6 15.4 14.9 18.9 12.4 4.4 5.8 

‘Includes 8 examinees who were 74 years of age at the time of interview, but became 75 years old by the time of examination. 

47 

3.7 

11.7 

- 

T 

4-74 4-5 

9,263 

6-11 12-17 

1,067 

3,545 27 194 222 318 379 413 431 

1,045 

Age in years 

18-24 

1,015 

25-34 3544 

1,170 793 630 

45-54 

108 

65.74l 

m1,658 

1,250 

73 

4.4 

5.8 

66 

4.0 

5.3 
been the determination of how imprecise the 

survey results may be because they come from a 

sample rather than from the measurement of all 

elements in the universe. 

The estimation of sampling errors for a 

study of the type of the Health and Nutrition 

Examination Survey is difficult for at least three 

reasons: (1) Measurement error and “pure” 

sampling error are confounded in the data-it is 

not easy to find a procedure that wiIl either 

completely include both or treat one or the 

other separately; (2) the survey design and 

estimation procedures are complex and, accordingly, require computationally involved techniques for the calculation of variances; and (3) 

hundreds of statistics are presented in the tables 

in this report, many for subclasses of the 

population for which there were small numbers 

of sample cases. Estimates of sampling error are 

obtained from the sample data and are themselves subject to sampling error when the number of cases in a cell is small or, even occasionally, when the number of cases is substantial. 

Estimates of the standard errors for selected 

statistics used in this report are presented in the 

detailed tables. These estimates have been prepared by a replication technique that yields 

overall variability through observation of variability among random subsamples of the total 

sample. Again, readers are reminded that these 

estimated sampling errors do not reflect any 

residual bias that might still be present after the 

attempted correction for nonresponse. The 

standard error is primarily a measure of sampling 

variability, that is, of the variations that might 

occur by chance because only a sample of the 

population has been surveyed. As calculated for 

this report, the standard error also reflects part 

of the variation that arises in the measurement 

process. It does not include estimates of any 

biases that might exist in the data. The chances 

are about 68 out of 100 that an estimate from 

the sample would differ from a complete census 

by less than the standard error. The chances are 

about 95 out of 100 that the difference would 

be less than twice the standard error and about 

99 out of 100 that it would be less than 2% 

times as large. 

Reliability of Measurements 

Supervised testing with some partial replication was done by the senior ophthalmologists 

from NE1 at 24 of the 35 examination locations 

for 230 examinees (2.5 percent of the 9,263 

ophthalmology examinations given those 4-74 

years of age) included both determination of 

motility status and prescription in present 

glasses from which it is possible to obtain an 

estimate of the reliability of these tests and 

measurements. This “replication” of the survey 

ophthzdmologist’s examination was done in the 

first two sessions of each of these 24 locations. 

Motility.-Motility examination results show 

at least a 97-percent agreement on the presence 

or absence of a given motility defect for all 

conditions except esophoria and exophoria in 

which the agreement was 82 percent (table IV). 

Table IV. Examiner-observer agreement in motility condition identification’on 230 replicate examinations: Health and Nutrition Examination Survev 

(HANES I). 1971-1972 

Abnormal motility 

condition 

Tropia: 

Eso-exo ....................................... 

Hyper-. ........................................ 

Comitant-incomitant ................... 

Phoria: 

Esoexo ....................................... 

Hyper-. ........................................ 

Nystagmus ........................................ 

Examiner-observer 

agreed-total 

- 

ll Examinerobserver agreed 

Normal 

Number 

of 

replicates 

Percent Number Percent 

of of of 

225 97.8 212 92.2 

228 99.1 227 98.7 

224 97.4 216 97.4 

189 82.2 167 72.6 

320 100.0 229 99.6 

229 99.6 228 

T Abnormal 

ziiEj?z 

- 

T Examinerobserver 

disagreed on types 

of abnormalities 

- 

T 

Number Percent 

of of 

replicates replicates 

5 2.2 

2 0.9 

6 2.6 

41 

1 

17.8 

0.4 

: 

Percent 

disagreement 

within 

abnormal 

groups1 

27.8 

66.7 

42.9 

65.1 

50.0 

‘By examiner and/or observer. 

109 
However, the results indicate some difficulty in 

condition identification. Of those examinees 

identified by examiner or observer as having a 

specific eye muscle problem, examiner-observer 

agreement ranges from 33 percent for hypertropia to 100 percent for hyperphoria. 

Some further indication of the reliability of 

the identification of motility defects on the 

examination is available for all examinees from a 

comparison between this initial identification 

and the significant eye conditions diagnosed by 

the survey ophthalmologists. Less than 0.1 

percent of the examinees were diagnosed as 

having a significant tropia that was not detected 

on the initial part of the examination, and 98 

percent of those conditions of tropia initially 

detected were considered significant pathology 

after more complete examination. 

Refraction status.-An assessment of the 

reliability of the lensometer measurements of 

the prescription in the present glasses or contact 

lenses is possible also from the 230 replicate 

examinations. 

Frequency and percent distributions of the 

absolute differences between the survey ophthalmologist examiner and NE1 senior ophthalmologist observer for sphere, cylinder, and axis 

of deviation are presented in tables V and VI. 

As a summary statistic of the distribution of 

differences between examiner and observer 

shown in tables V and VI, the percentage 

technical error of measurement ZJ is computed 

as follows: 

100 

c df 

i= 1 

v=T- 2n 

where 

n is the number of pairs of replicate measurements in the study, 

Table V. Frequency and percent distribution of absolute differences between examiner and observer determinations of spherical and 

cylindrical power in lens for each eye: Health and Nutrition Examination Survey (HANES I), 1971-1972 - 

F 

- 

f 

Sphere Cylinder 

r Right eye T Right eye Left eye Left eye 

Fre- Percent r distriquency bution 

Absolute difference (in diopters) 

Frequency Fre- Percent 

distri- Frequency 

Percent 

distribution 

72 100.0 73 100.0 72 1’ 100.0 

49 

3 

9 

1 

1 

3 

3 

1 

1 

1 

68.1 

4.2 

12.5 

1.4 

1.4 

4.2 

55 

17 

1 

75.3 

23.3 

1.4 

58 80.6 

3 4.2 

9 12.5 

2 2.8 

4.2 

1.4 

1.4 

1.4 

Percent 

distribution 

100.0 

61.6 

12.3 

17.8 

1.4 

2.7 

1.4 

2.7 

Total . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 

45 

9 

13 

1 

2 

1 

2 

0.00 D ..................................................................... 

0.12 D ..................................................................... 

0.25 D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

0.28 D ..................................................................... 

0.43 D ..................................................................... 

0.50 D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

0.62 D ..................................................................... 

0.75 D.. ................................................................... 

0.87 D ..................................................................... 

1 .OO D ..................................................................... 

1.38 D.. ................................................................... 

2.50 D.. ................................................................... 

4.00 D ..................................................................... 

Lens Sphere Cylinder 

Average difference 

(in diopters) 

Both lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.05 -0.06 

Right eye lens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

t 

-0.12 -0.03 

Left eye lens . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.02 -0.08 

110 
Table VI. Frequency and percent distribution of absolute differences between examiner and observer determinations of 

axis of deviation in lens for each eye: Health and Nutrition 

Examination Survey (HANES I), 1971-1972 

Absolute difference 

(in degrees) 

Total . . . . . . . . . . . . . . 52 100.0 48 100.0 

0” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . “0 

I ............................. 

2O ............................. 

3O ............................. 

4” ............................. 

5O ............................. 

7O ............................. 

10” ........................... 

15O ........................... 

2o” ........................... 

30° ........................... 

33O ........................... 

35” ........................... 

45O ........................... 

60’ ........................... 

72” ........................... 

85” ........................... 

86” ........................... 

87’ ........................... 

89’ ........................... 

90” ........................... 

91° ........................... 

92O ........................... 

93” ........................... 

95O ........................... 

l75O ......................... 

177O ......................... 

178’ ......................... 

Axis 

Right eye 

Frequency 

19 

2 

4 

2 

4 

5 

1 

1 

1 

1 

1 

1 

2 

1 

3 

1 

1 

1 

1 

Percent 

distribution 

36.5 

3.8 

7.7 

3.8 

7.7 

9.6 

1.9 

1.9 

1.9 

1.9 

1.9 

1.9 

3.8 

1.9 

5.8 

1.9 

1.9 

1.9 

1.9 

T Left eye 

Frequency 

15 312 

2 42 

2 4.2 

4 8.3 

1 2.1 

6 12.5 

1 2.1 

1 2.1 

1 

1 

1 

1 

3 

1 

3 

1 

7 

1 

1 

1 

2.1 

2.1 

2.1 

2.1 

6.2 

2.1 

6.2 

2.1 

2.1 

2.1 

2.1 

2.1 

Percent 

distribution 

Lens I Average difference 

(in degrees) 

Both lenses ...................... 

Right eye lens.. ................... 

Left eye lens.. ..................... 

df is the square of the difference between 

members of the ith pair of replicate measurements(i=l,...,n),and 

X is the arithmetic mean of the 2 n measurements in the study. 

The percentage technical error u can be 

interpreted as a “coefficient of variation” and is 

a dimensionless constant. It essentially describes 

the size of measurement error relative to the 

mean of a measurement. As one measure of the 

differences between examiner and observer, the 

values of u are as follows: 

Right eye V 

Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.1 

Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.8 

Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37.3 

Left eye V 

Sphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.8 

Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.0 

Axis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.3 

These values of v indicate that refraction was 

replicated with some difficulty. Upon further 

examination, the average difference between 

examiner and observer given in tables V and VI 

indicates that no measurement bias exists. 

Bias and Precision of Estimates From 

Medical History Responses 

Comparable data from the medical history 

on the wearing of glasses or contact lenses and 

trouble seeing were available for those 6-74 

years of age from the entire 65 stands of the 

national probability sample examined in 197 l1974. Field collection operations for this Health 

and Nutrition Examination Survey were started 

in April 197 1 and completed in June 19 74. 

Among the 24,513 selected in the national 

probability sample to represent the 13 1.4 million of that age in the civilian noninstitutionalized population, 17,854, or 72.8 percent, 

were examined and completed their medical 

histories. When adjustments are made for differential sampling ratios and nonresponse in the 

age-sex-income-defined population subgroups, 

this represents an effective response rate of 74.4 

percent. 

National estimates for the medical history 

items included in this report have been based on 

the entire 65stand sample rather than limited, to 

the 35-stand national probability sampIe for 

111 
which the ophthalmology examination findings 

were available, since the precision of the estimates from this larger sample will be greater. 

Comparison of medical history responses 

from the 35 and 65 examination-location national probability samples permits an assessment 

of the extent of bias, if any, that may exist in 

the history and eye examination findings from 

the 35-stand sample for which the ophthak 

mology examination data are available and the 

extent of improvement in precision of the 

estimates gained by the use of the 65-location 

history data. 

Bias.-Medical history estimates for the 35- 

stand subsample (table VIII) are consistent with 

the 65-stand sample (table 34). Furthermore, 

the consistency of ophthalmology with medical 

history findings for 35 stands implies that the 

selection procedures for choosing the 35-stand 

subsample did not bias the ophthalmology estimates presented here. 

Precision.-The components of variability 

that have been discussed include measurement 

error and sampling variability. In particular the 

loss in estimation precision incurred in using the 

probability subsample of 35 stands of the full 

65-stand sample is of interest here. 

The estimated coefficients of variation (i.e., 

the standard error of the mean divided by the 

mean, or (100 S, /Z) of the medical history 

estimates given in tables VIII and VIIIA for 35 

stands and tables 34 and 34A for 65 stands are 

compared in table VII. The increase in precision for estimates based on the total population 

6-74 years ranges from 0.02 to 0.78. The median 

of 0.40 indicates that a 40-percent increase in 

precision accompanied the twofold increase in 

sample size. 

Selected medical history items 

Table Vtl. Precision of selected medical history estimates for the 65stand sample and the 35stand subsample, by sex: United States, 

1971-1972and 1971-1974 

~ 

Coefficient of variation (percent) 

Ever have trouble seeing.. ................................................................................. 

Does (did) have trouble seeing even when wearing glasses or contact lenses ...... 

Visited doctor about trouble seeing ................................................................. 

Ever miss school or work because of trouble with eyes.. .................................. 

Ever wear glasses or contact lenses ................................................................... 

Yes, glasses ................................................................................................. 

Yes, contact lenses.. ..................................................................................... 

Yes, contact lenses and glasses.. ................................................................... 

Still wear them ................................................................................................. 

When worn: 

All the time ................................................................................................ 

For reading or close work.. ......................................................................... 

For distance vision ...................................................................................... 

At other times ............................................................................................ 

Age first worn: 

04 years.. ................................................................................................... 

5-9 years ..................................................................................................... 

IO-19 years.. ............................................................................................... 

20-29 years.. ............................................................................................... 

30-39 years.. ............................................................................................... 

4049 years.. ............................................................................................... 

50 years or older.. ....................................................................................... 

I 

2.1 1.2 3.4 1.9 2.1 1.2 

6.8 4.4 9.8 7.4 7.0 4.8 

0.6 0.4 0.9 0.5 0.8 0.5 

11.7 7.4 19.4 11.4 11.9 7.1 

1 .O 0.8 2.2 1.2 1.5 1 .O 

1.1 0.8 2.1 1.1 1.7 1.1 

30.0 16.7 58.0 30.0 30.0 16.2 

40.0 8.6 80.0 12.5 40.0 9.5 

0.7 0.5 1 .o 0.7 1.2 0.7 

3.3 1.8 3.7 2.0 4.3 2.3 

0.7 0.4 0.9 0.6 1.1 0.6 

2.6 1.3 3.0 1.7 3.4 1.6 

3.2 1.5 3.5 1.6 4.1 2.0 

12.0 11.7 43.3 

6.3 3.9 8.4 

3.0 1.7 4.6 

5.7 3.5 7.8 

6.8 4.3 11.2 

4.4 2.6 5.4 

6.1 3.6 5.8 

22.2 

::: 

5.1 

7.8 

4.0 

4.6 

15.4 12.1 

7.7 5.2 

3.9 2.0 

6.9 4.4 

7.6 4.6 

5.3 3.3 

9.7 5.4 

112 
Table VIII. Prevalanca rates 

Sex and selected medical 

items 

for selected medical history items pertaining to the eye, and percent distribution by age lenses first worn, 

amona oooulation 6-74 years, by age and sex: United States, 1971-1972 I. . 

II 

All Age in years ages. 

6.74 

years 6-111 12-17 18-24 25-34 3544 45-54 55-64 65-74 

Both sexes Rate per 190 persons 

Ever have trouble seeing ........................................... . 

Does (did) hava trouble seeing even when wearing 

glasses or contact lensas ......................................... 

Visited doctor about trouble seeing ......................... 

Ever miss school or work because of trouble with 

eyes ...................................................................... 

Ever wear glasses or contact lenses ............................ 

Yes, glasses ......................................................... . 

Yes, contact lenses .............................................. 

Yes, contact lenses and glasses ............................ 

Still wear them ......................................................... 

When worn: 

All the time ........................................................ 

For reading or close work ................................... 

For distance vision .............................................. 

At other times .................................................... . 

55.0 17.6 40.3 49.1 48.4 54.9 82.8 83.6 86.0 

12.4 11.4 

93.3 291.2 St:: 9% 

13.0 

91.6 

12.6 13.8 18.1 

95.0 97.8 97.5 

3.6 

58.7 

362.5 

30.7 

30.2 

87.6 

3.0 

14.5 

-WV 

3.9 3.5 

35.9 51.5 

34.2 44.2 

0.3 1.2 

___ 

79.8 80.6 79.5 

4.6 3.0 

52.8 61.7 

47.0 58.9 

1.8 0.5 

0.8 0.2 

74.7 77.0 

813 

87.4 

0.4 

9% 

4.0 

94.1 

93.0 

99.0 

3.0 

96.6 

96.1 

0.0 

9% 

52.7 60.2 60.7 53.3 47.4 44.5 40.8 60.5 

90.6 92.3 88.5 83.2 82.1 86.9 93.3 96.7 

62.0 69.4 70.3 69.2 63.5 55.9 47.5 65.2 

58.2 63.3 69.2 61 .O 56.4 51.7 45.5 62.1 

2: 

72.7 

71.5 

Age first worn:’ 

04 years ............................................................. 

5-9 years .............................................................. 

1 O-l 9 years ......................................................... . 

20-29 years .......................................................... 

30-39 years ......................................................... 

4049 years .......................................................... 

50 years or older ................................................. . 

Male 

Ever have trouble seeing ............................................ 

Does (did) have trouble seeing ewn when wearing 

glasses or contact lenses ....................................... 

Visited doctor about trouble seeing ......................... 

Evar miss school or work kcause of trouble with 

WW ....................................................................... 

Ever wear glassas or contact lenses ............................ 

Yes, glasrs ......................................................... . 

Yas, contact lensas ............................................. 

Yes, contact lenses and glasses ............................. 

Still weer them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work .................................... 

For distance vision ............................................... 

At other times ..................................................... 

Aga first worn:’ 

O-4 years .............................................................. 

5-9 years ............................................................. . 

lO-19years ......................................................... . 

20-29 years .......................................................... 

30-39 years .......................................................... 

4049 years .......................................................... 

50 years or older .................................................. 

See footnotes at end of table. 

Percent distribution 

31.0 -I 0.3 

310.9 

3.3 

36.2 

60.6 

1.7 2.1 0.8 0.5 

19.1 16.1 10.2 3.9 

69.6 54.6 38.1 16.6 

9.6 22.9 18.8 11.7 

3.4 3.6 

10.9 11.0 

13.9 8.5 

14.7 12.1 

34.1 30.6 

23.1 33.9 

333.2 

313.1 

311.4 

321.1 

39.4 

. . . 

Rate per 100 parsons 

49.1 80.4 78.7 82.1 

7.2 11.6 11.9 14.2 

94.9 64.3 96.3 95.1 

5z 

52.3 

0.4 

4.0 4.5 3.2 

84.6 90.4 93.4 

83.0 89.5 92.8 

80.6 

0.1 

95.3 99.1 

0.1 

96.7 

49.0 39.3 53.3 

84.3 93.2 94.6 

60.7 46.3 62.0 

57.1 43.6 54.9 

f$:X 

66.2 

64.4 

49.8 16.3 35.3 

10.7 7.2 5.9 

93.2 292.4 89.5 

4.1 

52.3 

357.0 

30,5 

30.2 

88.2 

2.7 

12.1 

3.7 

32.5 

31.8 

-I 

-3 

72.3 81.9 

51.9 54.8 

90.6 86.4 

61.2 72.2 

57.4 58.0 

60.9 

90.2 

El 

42.3 42.2 

9.9 13.4 

88.7 90.5 

4::; 4: 

37.8 39.9 

1.4 1.5 

1.3 

83.5 73.1 

59.8 53.2 

86.8 85.8 

72.4 64.8 

68.2 61.1 

Percent distribution 

2.0 

34.1 

63.9 

. . . 

. . . 

. . . 

. . . 

0.7 

16.7 

49.4 

24.8 

8.4 

, t . 

. . . 

0.5 - 

I I 

0.3 

2.6 4.0 2.2 

30.6 

310.5 

328.1 

;::*g 

324:3 

312.6 

0.7 

9.5 

29.0 

19.1 

25.4 

16.4 

2::: 

65.5 

11.8 

. . . 

. . . 

. . . 

-_ 

.-. 

-_ 

. . 

.I 

13.7 5.2 6.7 

11.1 I 11.6 I 5.5 

113 
Table VI I I. Prevalence rates for selected medical history items pertaining to the eye, and percent distribution by age lenses first worn, 

among population 6-74 years, by age and sex: United States, 1971-1972-Con. 

Sex and selected medical 

items 

Female 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ....................................... 

Visited doctor about trouble seeing.. ........................ 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ............................................. 

Yes, contact lenses and glasses.. ........................... 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision.. ............................................. 

At other times ..................................................... 

Age first worn:” 

O-4 years.. ............................................................ 

5-9 years.. ............................................................ 

10-I 9 years.. ........................................................ 

20-29 years.. ........................................................ 

30-39 years.. ........................................................ 

4049 years.. ........................................................ 

50 Years or older.. ................................................ 

- 

-IAll Age in years 

ages, 

6-74 

years 6-II1 12-17 18-24 25-34 3644 45-54 55-64 

Rate per 100 persons 

59.9 18.8 45.4 55.4 53.8 60.4 84.9 87.8 89.0 

13.6 14.6 10.9 9.7 12.7 11.3 13.4 15.3 20.9 

93.4 i!90.3 81.0 94.1 92.3 89.6 95.6 98.9 99.2 

3.2 3.3 

64.7 17.0 

367.6 ___ 

30.8 ___ 

30.2 _-- 

87.2 85.3 

4.2 3.4 

39.3 61.2 

36.7 50.2 

0.6 1 .o 

2.3 2.7 

60.4 68.4 

53.1 65.2 

2.0 0.5 

0.5 0.4 

75.7 74.2 

3.3 

93.5 

91.4 

0.8 

3.6 

97.3 

96.1 

79.5 77.0 97.7 99.0 

2.8 

99.1 

98.5 

0.0 

0.2 

98.8 

53.3 64.1 60.6 49.3 43.5 41.2 42.0 66.4 74.3 

90.5 96.5 86.9 81.0 79.7 88.8 93.5 98.5 98.7 

62.6 67.3 72.2 67.3 62.6 52.4 48.5 67.9 77.3 

58.8 67.1 68.5 56.8 53.3 47.6 47.1 67.9 76.4 

31.3 --- 

311.2 -- 

337.0 -- l- 313.5 -- 

311.3 -- 

3qa.7 --- 

37.0 -- 

4.4 

37.9 

57.7 

. . . 

. . . 

. . . 

. . . 

Percent distribution 

2.1 

17.6 

72.1 

8.2 

. . . 

. . . 

. . . 

3.0 

15.7 

57.9 

21.6 

1.8 

0.9 

10.8 

45.1 

18.6 

16.5 

8.2 

0.5 

5.0 

19.0 

12.2 

20.7 

39.4 

3.2 

2.8 

15.6 

15.8 

16.2 

32.6 

17.1 

0.3 

4.6 

14.1 

10.6 

12.5 

31.2 

26.6 

‘Questions were answered by parent. 

‘Visited doctor about vision problem other than trouble seeing at night or in dark. 

‘Does not include 6-11 years. 

4Average age is 6.9 years. 

‘Average age is 7.0 years. 

114 
selected medical history items pertaining to the eye,and percent distribution by 

lation 6-74 veals, bv age and sex: United States, 1971-1972 

Table VIIIA. Standard errors for prevalence rates f# 

age lenses first worn, among po 

Sex and selected medical 

history items 

Both sexes 

or 

Pul 

- 

I 

.._ 

All Age in years 

ages. 

6-74 

years 6-l 1 1 12-17 18-24 25-34 3544 45.54 55-64 65-74 

Standard error of rate 

Ever have trouble seeing.. .......................................... 

Doas (did) have trouble seeing even when wearing 

glasses or contact lenses.. ........................................ 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses ............................ 

Yes, glasses .......................................................... 

Yes, contact lenses.. ............................................ 

Yes, contact lensas and glasses ............................. 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision ............................................... 

At other times ..................................................... 

1.17 1.39 1.49 2.10 2.49 2.03 1.86 2.41 1.25 

0.85 3.06 1.84 1.69 1.70 1.39 1.77 1.75 1.40 

0.60 23.85 1.28 1.75 1.64 1.25 1 .I7 0.67 0.58 

0.42 

0.58 

30.69 

30.21 

30.08 

0.64 

1.76 

0.61 

1.60 

1.88 

0.66 

1.74 

-.d 

4.30 

5.50 

3.37 

4.41 

5.10 

0.76 0.57 

1.68 2.20 

1.86 1.73 

0.22 0.57 

2.74 2.52 

1.18 0.58 1.13 

1.76 1.41 0.91 

2.24 1.40 1.04 

0.63 0.27 0.29 

0.55 0.16 0.03 

2.79 1.69 0.69 

3.16 4.01 2.86 2.17 2.89 2.97 1.77 

1.67 2.79 1.78 2.15 1.13 1.35 0.43 

2.22 3.04 2.78 2.04 3.35 2.90 1.52 

2.52 4.22 3.61 2.63 2.83 3.39 1.82 

Standard error of percent 

Age first worn:” 

0-4 years .............................................................. 

5-9 years .............................................................. 

1 O-l 9 years .......................................................... 

20-29 years .......................................................... 

30-39 years .......................................................... 

40-49 years .......................................................... 

50 years or older .................................................. 

30.12 

30.69 

31 .Ol 

:yj*;; 

so:93 

30.57 

1.17 

3.65 

3.62 

0.43 0.55 

2.67 1.67 

.,. 

2.17 

1.96 

2.26 

1.92 

. . . 

. . . 

. . . 

. . . 

. . . 

1.52 

.*. 

0.36 

2.55 

2.56 

2.32 

1.99 

2.48 

. . . . . . 

Male Standard error of rate 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses .......................................... 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses ............................ 

Yes, glasses .......................................................... 

Yes, contact lenses ............................................... 

Yes, contact lenses and glasses.. ........................... 

Still wear them .......................................................... 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision.. ............................................. 

At other times ..................................................... 

1.67 1.94 2.41 

1.05 3.62 2.21 

0.81 24.97 2.12 

0.70 

1.15 

31.19 

30.29 

30,16 

0.87 

0.96 

2.23 

0.76 

2.37 

2.69 

10.00 3.67 

1.94 8.56 6.25 

0.84 6.49 2.67 

1.81 6.56 5.72 

2.01 7.40 4.80 

3.16 4.22 3.56 

4.49 4.00 2.10 

2.30 3.25 1.88 

1.39 2.19 0.94 

2.82 2.99 2.75 

2.84 3.54 3.03 

1.10 0.80 0.46 

1.28 

2.65 5.08 2.43 

6.01 4.71 4.19 

3.92 3.69 4.39 

4.60 5.08 4.63 

6.45 5.91 4.35 

Standard error of percent 

Age first worn:5 

O-4 years .............................................................. 

5-9 years.. ............................................................ 

10-I 9 years.. ........................................................ 

20-29 years .......................................................... 

30-39 years .......................................................... 

40-49 years .......................................................... 

50 years or older .................................................. 

See footnotes at end of table. 

30.26 

30.88 

31.29 

30.97 

31.29 

31.32 

30.73 

-- 1.49 

-- 5.54 

- 5.66 

- . . . 

-- . . . 

- .., 

-- . . . 

0.97 

4.50 

3.91 

4.55 

. . . 

0.15 

4.07 

4.69 

3.71 

3.21 

. . . 

. . . 

0.60 

3.23 

3.70 

3.41 

3.39 

4.07 

. . . 

0.73 

0.70 

0.66 

0.01 

0.13 

0.50 

1 .oo 

1.47 

1.58 

0.42 

0.31 

0.90 

2.10 

1 A5 

2.35 

2.38 

1.57 

0.13 

1.28 

1.36 

0.85 

0.94 

1.24 

1.97 

1.03 

1.83 

1.75 

2.12 

2.24 

2.03 

3.03 3.66 1.66 

1.55 2.53 1.77 

1.56 1.31 1.39 

1.71 1.89 0.77 

2.37 3.07 1.49 

2.36 3.12 1.52 

0.06 

1.34 0.60 

0.07 

0.90 

3.66 4.54 2.80 

1.56 2.47 0.57 

4.21 4.29 2.51 

3.51 5.20 3.01 

1.43 

1.68 

2.25 

2.98 

3.84 

3.46 

0.52 

1.03 

2.64 

1.98 

2.67 

3.09 

2.49 

0.05 

0.79 

1.49 

1.26 

1.13 

1.66 

3.20 

115 
Table VII IA. Standard errors for prevalence rates for selected medical history items pertaining to the eye, and percent distribution by 

age lenses first worn, among oooulation 6-74 years, by age and sex: United States, 1971-1972-Con. 

Sex and selected medical 

history items 

All Age in years 

ages, 

6-74 

years 6-l I1 12-17 is-24 25-34 35-44 45-54 55-64 

I 

65-74 

Female Standard error of rate 

Ever have trouble seeing.. .......................................... 

Does (did) have trouble seeing even when wearing 

glasses or contact lenses.. ....................................... 

Visited doctor about trouble seeing .......................... 

Ever miss school or work because of trouble with 

eyes ....................................................................... 

Ever wear glasses or contact lenses.. .......................... 

Yes, glasses .......................................................... 

Yes, contact lenses.. ............................................. 

Yes, contact lenses and glasses.. ........................... 

Still wear them.. ........................................................ 

When worn: 

All the time ......................................................... 

For reading or close work.. .................................. 

For distance vision.. ............................................. 

At other times ..................................................... 

I .28 3.07 

0.95 

0.74 

2.09 

4.24 

iz5.50 

0.96 

1.74 

-- 

-- 

___ 

4.25 

4.73 

3.41 

4.58 

5.09 

3.60 

2.93 

0.38 

0.97 

31.14 

30.24 

30.08 

1.09 

1.39 

3.23 

3.22 

0.44 

3.31 

2.28 

0.96 

2.1 1 

2.39 

4.24 

3.08 

3.11 

4.40 

3.19 2.46 1.84 

2.04 1.81 1.70 

1.66 1.83 1.23 

0.76 0.66 0.63 

3.03 2.06 1.99 

2.22 2.75 2.19 

0.24 0.92 

0.40 

0. z! 8 

0. 9 

3.56 3.43 2.23 

4.60 3.25 2.52 

3.06 I .28 1.69 

4.46 3.41 2.59 

4.17 3.79 2.56 

Standard error of percent 

Age first worn:6 

O-4 years.. ............................................................ 

5-9 years.. ......................................... .:................. 

lo-19 years.. ........................................................ 

20-29 years .......................................................... 

30-39 years.. ........................................................ 

40-49 years.. ........................................................ 

50 years or older.. ................................................ 

___ 

___ 

_I 

- 

I_ 

-_ 

1.50 0.85 

4.44 2.54 

4.56 2.64 

. . . 1.86 

. . . * . . 

. . . . . . 

. . . . . . 

‘Questions were answered by parent. 

‘Visited doctor about vision problem other than trouble seeing at night or in dark. 

‘Does not include 6-11 years. 

4Standard error of average age is 0.19. 

‘Standard error of average age is 0.36. 

‘Standard error of average age is 0.25. 

0.86 

1.96 

2.37 

1.59 

0.65 

. . . 

. . . 

0.46 

2.89 

3.66 

2.37 

2.17 

1.77 

. . . 

2.27 3.11 I -58 

2.77 2.10 1.71 

1.82 0.79 0.28 

1.16 

1.03 

1.77 

0.55 

0.75 

1.26 

1.36 

1.14 0.66 

1 .Ol 

0.25 

0.39 

0.02 

0.22 

0.43 

3.98 3.81 

1.72 0.83 

4.03 3.68 

3.94 3.77 

2.63 

0.57 

2.59 

2.34 

0.36 

1.44 

3.62 

1.70 

3.06 

3.01 

1.24 I 1.42 

2.29 

2.54 

3.16 

3.74 

2.95 

I 

I 

0.22 

1.84 

2.08 

1.30 

1.39 

1.70 

2.04 

0 0 0 

116 
APPENDIX II 

DEMOGRAPHIC AND SOCIOECONOMIC TERMS 

Age.-The age recorded for each examinee 

was the age at last birthday at the time of 

examination. The age criterion for inclusion in 

the sample used in this survey was defined as age 

at time of census interview. In this sample there 

were a few examinees who were 74 years of age 

at the time of interview but 75 years of age at 

examination. In the adjustment and weighting 

procedures used to produce national estimates, 

these persons were included in the 74-year-old 

group. 

Race.-Race was recorded as “white,” 

“Black,” or “other.” “Other” included Japanese, 

Chinese, American Indian, Korean, Eskimo, and 

all races other than white and Black. Mexicans 

were included with white unless definitely 

known to be American Indian ,or of other 

nonwhite race. Blacks and persons of mixed 

Black and other parentage were recorded as 

Black. When a person of mixed racial background was uncertain about his race, the race of 

his father was recorded. 

Geopaphic region. -The 48 contiguous 

States and the District of Columbia (not Alaska 

and Hawaii) were stratified into 4 broad geographic regions of about equal population size. 

With a few exceptions, the compositions of the 

regions were as follows: 

Region States included 

Northeast.. . . . . . . . . Maine, New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New 

York, New Jersey, Pennsylvania 

Midwest . . . . . . . . . . . . . Ohio, Michigan, Indiana, Illinois, Wisconsin, Minnesota, 

Iowa, Missouri 

south.. .............. 

West.. ................ 

Delaware, Maryland, Virginia, 

West Virginia, Kentucky, 

Arkansas, Tennessee, North 

Carolina, South Carolina, 

Georgia, Florida, Alabama, 

Mississippi, Louisiana, District of Columbia 

Washington, Oregon, Idaho, 

Montana, Wyoming, Colorado, Utah, Nevada, California, Arizona, New Mexico, 

Texas, Oklahoma, Kansas, 

Nebraska, South Dakota, 

North Dakota 

In a few instances the actual boundaries of 

the regions do not follow State lines. Some 

strata in the Midwest and South include PSU’s 

actually located in the West. Similarly, some 

strata in the West contain PSU’s located in the 

Midwest and South. 

Urban-ruraZ.-The classification of urbanrural areas is that used in the 1960 census. 

According to the 1960 definition, those areas 

considered urban are: (1) places of 2,500 inhabitants or more incorporated as cities, boroughs, villages, and towns (except towns in New 

England, New York, and Wisconsin); (2) the 

densely settled urban fringe, whether incorporated or unincorporated, of urbanized areas; 

(3) towns in New England and townships in New 

Jersey and Pennsylvania that contain no incorporated municipalities as subdivisions and have 

either 2,500 inhabitants or more, or a population of 2,500 to 25,000 and a density of 1,500 

persons per square mile; (4) counties in States 

other than the New England States, New Jersey, 

and Pennsylvania that have no incorporated 

municipalities within their boundaries and have 

a density of 1,500 persons or more per square 

117 
mile; and (5) unincorporated places of 2,500 

inhabitants or more which are not included in 

any urban fringe. The remaining population is 

classified as rural. 

By means of the first digit of the identification code on the household questionnaire, the 

urban and rural population is divided into the 

following categories according to population: 

(1) urban, 3,000,OOO or more; (2) urban, 

l,OOO,OOO-2,999,999; (3) urban, 250,000- 

999,999; (4) urban, under 250,000; (5) urban 

not in urbanized area, 25,000 or more; (6) urban 

not in urbanized area, lO,OOO-24,999; (7) urban 

not in urbanized area, 2,500-9,999; and (8) 

rural. 

Family income.- The income recorded is the 

total income received during the 12 months 

prior to the interview by the head of the 

household and all other household members 

related to the head. This income is the gross cash 

income (excluding pay in kind) except in the 

case of a family with its own farm or business. 

In that instance net income is recorded. Also 

included is the income of a member of the 

Armed Forces living at home with his family 

(even though he is not considered a household 

member). If he is not living at home, allotments 

and other money received by the family from 

him are included in the family income figure. 

Education.-The only grades counted are 

those that have been attended in a “regular” 

school where persons are given formal 

education-either graded public or private 

schools, day or night, full-time or part-time 

attendance. A regular school is one that advances a person toward an elementary certificate 

or high school diploma or a college, university, 

or professional school degree. Education received in vocational, trade, or business schools 

outside the regular school system is not counted 

in determining the highest grade of school 

completed. If a person attended school in a 

foreign country, at an upgraded school, under a 

tutor, or under other special circumstances, the 

nearest equivalent of his highest grade attended 

is assigned. 

-- 000 

118 
APPENDIX Ill 

EYE CONDITION DEFINITIONS 

The following definitions adapted primarily 

from Dr. Frank W. Newell’s Ophthalmology, 

Principles and Concepts9 were used by the 

ophthalmologist examiners as a guide for uniformity in recording the findings from the parts 

of the eye examination included in this report: 

Tropia-(heterotropia manifest strabismus, 

squint, wall-eyed, or cross-eyed).-The condition 

in which an object in space is not imaged 

simultaneously on the (fovea centralis of the) 

retina of each eye, that is, in which fusion 

(retinal images from the two eyes perceived as a 

single object) is not achieved usually due to a 

disturbance of coordination of the extraocular 

muscles of the two eyes. Included are tropia 

conditions that are comitant or incomitant 

(noncomitant), intermittent, at near or distance, 

small or large angle, accommodative or nonaccommodative, secondary to sensory impairment (e.g., cataract, chorioretinitis, optic 

atrophy, anisometropia), congenital or acquired. 

Esotropia.-Tropia of any type in which the 

visual alignment of one or both eyes is deviated 

inward. 

Exotropia.-Tropia of any type in which the 

visual alignment of one or both eyes is deviated 

outward. 

Hypertropia.-Tropia of any type in which 

the visual alignment of one eye is elevated above 

that of the other. This condition frequently 

occurs in the presence of manifest esotropia or 

exotropia. 

Corn&ant tropia.-Tropia in which there is 

no apparent weakness of the extraocular muscles 

of either eye and the amplitude of deviation 

between the visual axes of the two eyes is equal 

in all cardinal directions of gaze. A and V 

syndromes, in which the angle of deviation is 

more marked on looking upward or downward, 

and oblique overactions were classed as comitant 

tropia unless clearly of an acquired nature. 

Incomitant (or noncomitant) tropia.-Tropia 

in which one or more of the ocular muscles or 

their nervous connections are impaired so that 

there is limitation in normal movement of the 

eye(s), as in Duane’s syndrome, primary or 

secondary myopathies, cerebral vascular accidents, Parinaud’s syndrome, or blowout fracture. This is frequently an acquired condition, 

the residual of systemic disease or impairment. 

Phoria (heterophoria).-That condition in 

which there is a latent tendency for misalignment of the visual axes of the two eyes (one eye 

deviating so as to look at a different image than 

the other eye) which is corrected by the fusional 

capacity of the eyes. The condition is apparent 

only when fusion (the retinal images from each 

eye perceived as a single object) is interrupted. 

Esophotia.-Latent tendency for the eye(s) 

to deviate inward. 

ExophoS-Latent tendency for the eye(s) 

to deviate outward. 

Hyperphotia.-Latent tendency for one eye 

to deviate upward. 

iVystagmus.-An involuntary, more or less 

rhythmic, back-and-forth movement of the eyes, 

independent of the normal movements that are 

not affected. The involuntary oscillations of the 

eye are usually lateral, but may also be vertical, 

rotary, or mixed rotary and lateral or vertical. 

Pendular nystagmus.-This type of rhythm 

of involuntary movement of the eyes is regular 

and approximately equal in both directions. 

Included here were the type found in ocular 

disease in which central vision either fails to 

develop or is lost before the age of 2 years, 

119 
spasmus nutans (the unilateral type occurring in 

children under 2 years of age and associated 

with head nodding), and miner’s nystagmus (a 

fine rapid pendular nystagmus). ‘Voluntary 

nystagmus was not included. 

Jerk nystagmus.-In which the rhythm of 

movement of the eyes is irregular, slow in one 

direction, followed by a rapid corrective movement in the opposite direction. Included here 

were latent nystagmus (elicited by covering one 

eye or making the brightness or clarity of retinal 

images unequal in the two eyes), end-point 

nystagmus (when associated with palsies of 

conjugate gaze and with disease, seen when the 

eyes are turned into a extreme position of, gaze), 

and congenital nystagmus (jerk type). 

000 

120 
APPENDIX IV 

RECORDING AND HISTORY FORMS 

Visual Acuity 

6. VISUAL ACUITY 

1. Optotype used. . . . . . . . . . . . . . . . . . . 1. 

2. Acuity cc OD 2. 

OS 

SC OD 

OS 

3. If not 20120, pinhole (Acuity). . . . . . . . .3. 

OD 

To be entered by coder 

10s 

@ i 0 Snellen 

2 q III. E 

0 006 +i0 w7 .*. -- 

s 0 Landolt 

4 0 Picture 

0 010 *: _ 

0 011 l - - 

Motility 

I 

C. MOTILITY I 

l.Tropia. . . . . . . . . . . . . . . . . . . . . . ..l.. ’ @ I 0 Eso 2 cj Exo 3 0 Neither 

/ g 1 E Per 2 g Not hyper 

014 1 Comitant a a lncomitant 

I-- --mm._ -- ____,____._ - ___.__m -_--_.- _____ ------ 

2. Phoria . . . . . . . . . . . . . . . . . . . . . . . . 2. / @ I 0 Eso 2 0 Exo 3 a Neither 

f @ I 0 Hyper 2 [3 Not hyper 

I-_ - __-_---___-- ______.L_. ---- .-_-. -_-- ---- ---- 

3. Nystagmus. . . . . . . . . . . . . . . . . . . . . . 3. ; @ I 0 Pendular 4 a Jerk-rotary 

I 

I 2 q Jerkhoriz. 5 0 No nystagmus 

I 

I s 0 Jerk-vert. 

I 

121 
Refraction-Nutrition Exam 

I. REFRACTION 

1. Present glasses 

2. If acuity less 

than 20/40, any 

improvement 

with spheres 

*To be entered by coder 

Refraction-Detailed Exam 

Eye Sphere 

035 '036 

OD lo+ 1 

I 

z@- ; --.-AD 

I 

04oJ 2141 

OS 

Jo+ I 

I 

zg- I --.--D 

1 OS 1 ::‘I--.-e-D 

045J 046J 

- 

2. If acuity less than OD ‘II+ 

2OJ40, retinoscopy 20- --.--.. D 

052J 053J 

- 

OS 1[7+ 

*To be entered by coder 20 - --,__ --D 

I Axis 

037J I 038 

I 

‘cl+ I 

I 0 

20- 1 --.--D --- 

-i 

037 

Cylinder 

‘cl+ 

20- --.--II 

042 043J 

‘cl+ 

2n- --e--D 

Q47J cM0J 

‘III+ 

so- --.--II 

054 

ICI+ 

2a- --.--0 

Axis VA 

039 

0 

--- 

044 

0 

--- 

g 05oJ 

- 

0 

--- C’-- 

056 

--- O C’-- 

PH 

C*-- 

g-- 

C’-- 

122 
Selectad Items From Medical History Questionnaire, Ages 6-11 

18. Does . . . have unusual trouble seeing at 

night or in the dark? 

18. / @ I 0 Yes 

I 

I z0No 

I 

I 9 0 Don’t know 

190. Has . . . ever had any other 

trouble seeing? 

1%. i @ I 0 Yes -Ask b 

z f-J No - SKIP to 20~1 

b. Was it because of either an eye injury, 

infection or other eye problem? 

be j @ 1 q Yes 

I 

(1) An eye iniury.. . . . . . . . . . . . . . . . . . 1 2uNo ’ 

- . . 

(2) An eye infection or other eye problem . . . 

i @ lOYes 

I 

I 2 0 No - If “No” to both (I) and (2) SKIP to 200 

c. Did he see a doctor about it? c. j @ I 0 Yes 

(1) An eye injury . . . . . . . . . . . . . . . . . . . I 20 No 

(2) An eye infection or other eye problem . . . / @ lOYes-Askd 

I 2ONo- If “No” to both (I) and (2) SK/P to 200 

d. What did he say the trouble was? 

I 

!Oa. Has . . . ever had an eye accident or eye 

injury that did not affect his vision? 

2Oa. i @ 1 Dyes-Askb 

I 

I 2 0 No - SKIP to 210 

b. Did he see a doctor about it? b./@ inYes 

I 20No 

Zla. Has . . . ever worn glasses or 

contact lenses? 

b. Does he still wear them? 

I 

2’a* 1 @ 

I 0 Yes - Ask b 

2 0 No - SKIP to 22 

1 

c. When does (did) he wear them? C. Yes 

Allthetime . . . . , . . . . . . . . . ,... . . . . i@ 10 2: 

For reading or close work . . . . . . . . . . . . . I @ 10 20 

For distance vision . . . . . . . . . . . . . . . . . j@lO 20 

At other times - Specify I@ 10 20 

d. Does (did) he have trouble with 

his vision even when wearing 

glasses (or contact lenses) ? 

e. How old was he when he first 

wore alasses (or contact lenses) ? 

d.I@ toYes 

I 

0. j (iGJ 

20 No 

-- Years 

2 Has. . . ever had to miss school because 

of trouble seeing or other trouble with 

his eyes? 

I 0 Yes 

20 No 

123 
Selected Items From Medical History Questionnaire, Ages 12-74 

150. Have you EVER had trouble seeing? 

b. Did you see a doctor about it? 

c. What did he say the trouble was? 

, 

150. ; @ I 0 Yes - Ask b 

I 

I 2 0 No -SKIP to 160 

b. 1 @ I C]Yes-Askc 

, 2 0 No -SKIP to 16a 

I 

I 

. I 

Ma. Have you ever worn glasses or contact 

lenses? 

160. 1 @ i OYes, glasses. . . . . . . . . . . . 

I 2 0 Yes, contact lenses . . . . . . . Ask b 

I 

I 3 0 Yes, contacts and glasses. . . 

I 

I 4 0 No - SKIP to 17 

I 

b. Do you still wear them? bj @ i 0 Yes 

I 

I 2 I-J No 

- 

16~. When da (did) you wear them? 164:. 1 

Allthetime . . . . . . . . . . . . . . . . . . . . . . . . 1 @ T’;I 2N& 

.For reading or close work, . . . . . . . . . . . . . . I@ 10 20 

For distance vision. . . . , . . . . , . . . . . . . . . i @ I 0 20 

At other times - Specify -/@ 10 20 

I 

d. Do (did) you have trouble with your 

vision even when wearing glasses or 

contact lenses? 

a. How old were you when you first wore 

glasses or contact lenses, whichever 

I2 

(d, ; @ I 0 Yes, with glasses 

I 

I 2 0 Yes, with contacts 

I 

I 3 0 Yes, with both 

I 

e. 1 @ : : “,“_ 4 years old 

I 

one was first in cese you have worn both? I 20 5- 9 years old 

I 

I 3 0 IO - 19 years old 

I 

I 4 0 20 - 29 years old 

I 

I 5 f-1 30 - 39 years old 

I 

I 6 f-1 40 - 49 years old 

I .- 

I 7 [J 50 years old or older 

I 

17. Have you ever had to miss work or school 

because of trouble seeing or other trouble 

17. I () 137 i C-Yes 

I 

with your eyes? I 2 [;j No 

I 

* “. S. GOVERNMENT PRINTING OFFICE : 1978 X0-937/L8 

124 
VITAL AND HEALTH STATISTICS Series 

Series 1. Programs and Collection Procedures.-Reports which describe the general programs of the National 

Center for Health Statistics and its offices and divisions and data collection methods used and include 

definitions and other material necessary for understanding the data. 

Series 2. Data Evaluation and Methods Research.-Studies of new statistical methodology including experimental tests of new survey methods, studies of vital statistics collection methods, new analytical 

techniques, objective evaluations of reliability of collected data, and contributions to statistical theory. 

Series 3. Analytical Studies.-Reports presenting analytical or interpretive studies based on vital and health 

statistics, carrying the analysis further than the expository types of reports in the other series. 

Series 4. Documents and Committee Reports.-Final reports of major committees concerned with vital and 

health statistics and documents such as recommended model vital registration laws and revised birth 

and death certificates. 

Series 10. Data From the Health Interview Survey.-Statistics on illness, accidental injuries, disability, use of 

hospital, medical, dental, and other services, and other health-related topics, all based on data collected 

in a continuing national household interview survey. 

Series 11. Data From the Health Examination Survey and the Health and Nutrition Examination Survey.-Data 

from direct examination, testing, and measurement of national samples of the civilian noninstitutionalized population provide the basis for two types of reports: (1) estimates of the medically defined 

prevalence of specific diseases in the United States and the distributions of the population with respect 

to physical, physiological, and psychological characteristics and (2) analysis of relationships among the 

various measurements without reference to an explicit finite universe of persons. 

Series 12. Data From the Institutionalized Population Surveys.-Discontinued effective 1975. Future reports from 

these surveys will be in Series 13. 

Series 13. Data on Health Resources Utilization.-Statistics on the utilization of health manpower and facilities 

providing long-term care, ambulatory care, hospital care, and family planning services. 

Series 14. Data on Health Resources: Manpower and Facilities.-Statistics on the numbers, geographic distribution, and characteristics of health resources including physicians, dentists, nurses, other health 

occupations, hospitals, nursing homes, and outpatient facilities. 

Series 20. Data on Mortality.-Various statistics on mortality other than as included in regular annual or monthly 

reports. Special analyses by cause of death, age, and other demographic variables; geographic and time 

series analyses; and statistics on characteristics of deaths not available from the vital records based on 

sample surveys of those records. 

Series 21. Data on Natality, Marriage, and Divorce.-Various statistics on natality, marriage, and divorce other 

than as included in regular annual or monthly reports. Special analyses by demographic variables; 

geographic and time series analyses; studies of fertility; and statistics on characteristics of births not 

available from the vital records based on sample surveys of those records. 

Series 22. Data From the National Mortality and Natal@ Surveys.-Discontinued effective 1975. Future reports 

from these sample surveys based on vital records will be included in Series 20 and 21, respectively. 

S&es 23. Data From the National Survey of Family Growth.-Statistics on fertility, family formation and dissolution, family planning, and related maternal and infant health topics derived from a biennial survey 

of a nationwide probability sample of ever-married women 15-44 years of age. 

For a list of titles of reports published in these series, write to: Scientific and Technical Information Branch 

National Center for Health Statistics 

Public Health Service 

Hyattsville, Md. 20782