Data from the

NATIONAL HEALTH SURVEY

Color Vision

Deficienciesin Youths

12-17 Yearsof Age

United States

Prevalence of color vision deficiencies, as identified on examination

with plates from the Ishihara Test and typed with the Hardy-RandRittler Test, among youths 12-17 Years, by aqe, sex, race, family

income, geographic region, and population size of place of residence.

DHEW Publication No. (HRA). 74-1616

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

Public Health Service

Series 11

Number 134

Health Resources Administration

National Center for Health Statistics

Rockville, Md. January 1974
Series 11 reports present findings from the National Health Examination

Survey, which obtains data through direct examination, tests, and measurements of samples of the U.S. population. Reports 1 through 38 relate

to the adult program, Cycle I of the Health Examination Survey. The

present report is one of a number of reports of findings from the children and youth programs, Cycles 11 and HI of the Health Examination

Survey. These latter reports from Cycles 11and HI are being published

in Series 11 but are numbered consecutively beginning with 101. It is

hoped this will guide users to the data in which they are interested.

Vital and Health Statistics-Series 1l-No. 134

For sale by the Superintendent of Documents, Lr.S. Government Printing Office,Washington, D.C. 20402- Price 70 cents

/“
NATIONAL CENTER FOR HEALTH STATISTICS

EDWARD B. PERRIN, Ph.D., Director

PHILIP S. LAWRBNCE,SC.D., Deputy Director

GAIL F. FISHER, Assistant Director for Health Statistics Development

WALT R. SIMMONS,M.A., Assistant Director for Research and Scientific Development

JOHN J. HANLON, M.D., Medical Advisor

JAMES E. KELLY, D.D,S,, Dental Advisor

EDWARDE. MINTY, Executive Officer

ALICE HAYWOOD,Information Officer

DIVISION OF HEALTH EXAMINATION STATISTICS

ARTHUR J. McDOWELL, Director

GARRIE J, LOSEE, Deputy Director

PETER V. V. HAMILL, M.D., Medical Advisor, Children and Youth Programs

HENRY W. MILLER, Chiej Operations and Quality Control Branch

JEAN ROBERTS, chief Medical Statistics Branch

COOPERATION OF THE BUREAU OF THE CENSUS

In accordance with specifications established by the National

Health Survey, the Bureau of the Census, under a contractual

agreement, participated in the design and selection of the sample,

and carried out the first stage of the field interviewing and certain

parts of the statistical processing.

Vital and Health Statistics-Series 1l-No. 134

DHEW Publication No. (HRA) 74-1616

Library of Ckmgress Catalog Gzrd Number 7$600230
CONTENTS

Page

Introduction -------------------------------------------------------- --

Source .ofData ------------------------------------------------------

The Vision Examination ------------------------------------------------

The Color VisionTests ----------------------------------------------

The IshiharaTest ---------------------------------------------------

The Hardy-Rand- Rittler Pseudoisochromatic Plates --------------------

Testing Methods ----------------------------------------------------

Quality Control -----------------------------------------------------

Findings -------------------------------------------------------------

Screening Results --------------------------------------------------

Prevalence --------------------------------------------------------

T~e of Deficiency --------------------------------------------------

Red-Green Deficiencies ---------------------------------------------

Severity of Deficiency -----------------------------------------------

Subtype ofRed-GreenDeficiency --------------------------------------

Red-Green Deficiencies by Selected Demographic Variables -------------

Blue-Yellow Deficiencies --------------------------------------------

Combined Red-Green and Blue-Yellow Deficiencies ---------------------

Agreementon Reexamination -----------------------------------------

Comparison With Other Studies -----------------------------------------

Summary -------------------------------------------------------------

References -----------------------------------------------------------

List of Detailed Tables ------------------------------------------------

Appendix I. Statistical Notes -----------------------------------------

The Survey Design --------------------------------------------------

Reliability ---------------------------------------------------------

Sampling and Measurement Error ------------------------------------

Small Numkrs -----------------------------------------------------

Appendix II. Demographic and Socioeconomic Terms --------------------

Appendix 111. Recording Sheet Used for Color Vision Testing --------------

Appendix IV. Youths With Both Red-Green and Blue-Yellow Color Vision

Deficiencies ---------------------------------------------------------

1

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3

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5

5

5

6

6

7

7

8

9

10

10

10

10

12

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15

28

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34
SYMBOLS

Data not available ---------------------------------------- ---

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

Quantity zero ---------------------------------------------- -

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

Figure does not meet standards of

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

David Slaby and Jean

INTRODUCTION

VISION DEFICIENCIES

IN YOUTHS

Roberts, Division of Health Examination Statistics

Presented in this report are data on the prevalence of color vision deficiencies in American

youths 12-17 years of age as estimated from the

Health Examination Survey of 1966-70. The data

are stratified by age, sex, race, geographic region, size of place of residence, and annual family

income. Comparisons are also made with the

findings from the 1963-65 Health Examination

Survey among children 6-11 years of age.

Color vision deficiency, commonly called

color blindness, manifests itself in everyday life

in the confusion of, or blindness to, one or more

primary colors, and its origins may be congenital

or acquired.1~2 Congenital defects occur in two

chief forms, total and partial. The former is very

rare and is generally associated with nystagmus

&d a central scotoma. All colors appear as grays

of differing brightness. The partial form is the

most common type of color vision defect and is

primarily an inherited condition transmitted

through the mother, who is usually unaffected. It

is probably due to the absence of one of the photopigments normally found in the foveal cones.2 In

most cases reds and greens are confused.

Acquired defects of color vision may often

develop in, the course of ocukfr, mainly retinal,

disease.~ Red-green defects are frequently characteristic of lesions of the optic nerve and optic

pathways, while blue-yellow defects are more

likely to result from lesions of the outer layers

of the retina. 2

Source of Data

The Health Examination Survey in which these

color vision data were collected is one of the major ongoing programs of the National Center for

Health Statistics. Data collection, analysis, and

publication of the resulting findings on the health

status of the United States population was authorized as” a continuing Public Health Service activity in the National Health Survey Act of 1956 by

the 84th Congress.

Three different programs are used to carry

out the intent of the National Health Survey.3 The

Health Interview Survey focuses primarily on the

impact of illness and disability upon. the lives and

actions of people in various segments of the

United States population. It collects health information from samples of people by means of

household interviews. The Health Resources Survey program gathers health data as well as health

resource and utilization information through surveys of hospitals, nursing homes, other resident

institutions, physicians’ offices, and other medical facilities and on the entire range of personnel

in the health occupations. The Health Examination

Survey, on which the data in this report are based,

is the only program in the National Center for

Health Statistics which collects data by direct

physical examinations, tests, and measurements

performed on preselected probability samples of

the United States population. This approach provides the most efficient and accurate way of obtaining diagnostic data on the prevalence of medically defined illness within the entire population.

It is the only program that secures information

on unrecognized or undiagnosed conditions as

well as physical, physiological, and psychological

measurements within the population under study.

The survey also collects medical history, demographic, and socioeconomic data from the sample

population which are then interrelated with the

examination findings.
The Health Examination Survey functions as

a series of separate programs referred to as

“cycles.” Each cycle is limited to some specific

segment of the United States population and to

specific aspects of the health of that population.

During the first cycle conducted in 1960-62, the

prevalence of certain chronic diseases and the

distribution of various physical and physiological

measures were determined among a probability

sample representative of the civilian noninstitutional adult population 18-79 years of age, as

described previously.4’5

The second cycle was a survey among noninstitutionalized children aged 6-11 in 1963-65,

the examination concentrating primarily upon

health factors related to growth and development. G

The third cycle focused upon youth. For this,

a probability sample of the noninstitutionalized

youths 12-17 years of age in the United States was

selected and examined. The examination program

for youth was designed to obtain basic measures

of growth and development as well as data on

other health characteristics for this segment of

the American population. The questiomaires and

examination content and procedures closely

paralleled those used in the survey of children so

as to obtain comparable information, using standard measures for the continuum from childhood

through adolescence. However, the examination

among youth was supplemented and specially

adapted, as necessary, to obtain data specifically

related to adolescent health. Examinations were

conducted by a pediatrician, assisted by a nurse,

and by a dentist. Tests were administered by a

trained psychologist, and a variety of tests were

given and measurements taken by laboratory Xray technicians. The survey plan, sample design,

examination content, and operation of this survey

have been described in a previous report.7

Field collection operations for the youths’

cycle began in March 1966 and were completed

in March 1970. In the program, 6,768 youths

were examined from the 7,514 youths selected in

the sample. This represents a response rate of

90 percent. The national sample is representative and the examined group is closely representative of the 22.7 million noninstitutionalized

youths 12-17 years of age in the United States

with respect to age, sex, race, geographic region,

population size of place of residence, and rate of

population change in the place of residence from

1950 to 1960.

In this program, as in the preceding survey

of children, examinations were conducted consecutively in 40 different locations throughout the

United States. Each youth during his single visit

was given a standardized examination by the examining team in the mobile units specially designed for the survey. An exception to the single

visit was made for girls whose urine specimen

was found positive for bacteriuria. They were

brought back for repeat urine tests. Prior to the

examination, demographic and socioeconomic data

on household members as well as the medical

history, behavioral, and related data on the youth

to be examined were obtained from his parents.

In addition, a Health Habits and History form was

completed by the youth before he arrived for the

examination and he completed a Health Behavior

questionnaire at the examination center. Ancillary

data were requested from the schooI the youth

attended. These data included his grade placement, teacher’s ratings of his behavior and adjustment, and health problems known to his

teacher. A birth certificate was obtained for each

youth to verify his age and to provide information

related to his condition at birth. Statistical notes

on” the survey design, reliability of the data, and

sampling and measurement error are shown in

appendix 1. Definitions of the demographic and

socioeconomic terms are in appendix II.

THE VISION

EXAMINATION

The vision examination for youth was developed under the guidance of ophthalmologists

Dr. J. Theodore Schwartz, National Eye Institute,

and Dr. Herbert A. Urdweider. It included

Tests to detect and “classify color vision

deficiencies.

Determination of the level of central visual ~

acuity (both binocular and monocular) at

distance and near.

Determination of the degree of lateral phoria

at distance and near. I

Determination of the degree and extgnt of

correctability of myopia at distance with the

2
use of simple spherical trial lense’s for those

scoring less than 20/20 (Snellen).

Measurement with a lensometer of the type

and degree of correction in the refractive

lenses worn by the examinee.

Color vision tests were performed with the examinee’s usual glasses or other refractive lenses.

The other vision tests were done without correction, and for those who had their glasses with

them, the distance tests were also done with their

usual correction.

In addition, each youth was given an eye examination by the survey staff pediatrician. The

examination included a careful general inspection

for evidence of abnormal conditions of the lids,

conjunctival, sclerae, pupils, and irides; a cover

test to detect the presence of any tropia; an inspection of the conjugate gaze; and determination

of the focusing or dominant eye. This report is

limlted to findings on the color vision tests. An

earlier report describes results of the visual

acuity tests. *

The Color Vision Tests

Two of the most reliable and widely used

color vision tests commercially available were

selected for the survey-The Ishihara Test for

Colour-Blindness (1960 edition, 24 plates, seven

of which were used) and the American Optical

Company’s Hardy -Rand- Rittler Pseudoisochromatic Plates (1957 edition, 24 plates). These permitted uniform testing in the time available and

were suitable for large-scale administration to

youths 12 through 17 years of age. Both tests

consist of pseudoisochromatic plates so designed

that the color defective individual will see no

difference between two or more color samples

which appear different to persons with normal

color vision. 10‘“ These plates contain numerals

or symbols represented in dots of various tints

set on a neutral background amid dots of the

same size but of tints which are most readily

confused with those of the numerals or symbols

by persons with the principal types of color vision

deficiencies, Individuals with color vision deficiencies are unable to see any numbers or patterns on some of the plates; on others they may

see a different number or pattern than that seen

by persons with normal color vision.

The Ishihara Test

The Ishihara Test for Colour-Blindness was

first published in Japan in 1917 and in its various

editions has been used extensively in color vision

testing. This test has been found to be very effective in differentiating between persons with

normal and deficient color vision}O-15 The 1960

edition, part of which was employed in the Health

Examination Survey, consists of 24 plates designed

to detect the existence of a color vision deficiency. 9 Seven of the plates found most reliable

were used for screening in this survey~l These

require the ability to correctly identify or indicate the absence of one or two colored numerals.

The Hardy -Rand-Rittler

Pseudoisochromatic Plates

The commerical version of the Hardy-RandRittler test (H-R-R) was first produced by the

American Optical Company in 1955 and was based

on the H- R-R Polychromatic Plates developed

earlier .16In 1957 a second commercial edition of

the H-R-R, which was used in this study, was

published. It consisted of four demonstration

plates, six screening plates, and 14 diagnostic

plates of the pseudoisochromatic type.lT This

H-R-R test is designed to serve three purposes:

A screening test to separate persons with

defective color vision from those with normal

color vision.

A qualitative diagnostic test to classify type

of color defect (whether protan, deutan, tritan, or tetartan).

A quantitative diagnostic test to indicate degree or severity of the defect.

The H-R-R requires only the ability to identify and indicate the position of colored circles,

triangles, and crosses. The neutral background

pattern of the plates is composed of small, gray

circular dots of varying sizes and shades. Set

amid the gray dots are dots of similar sizes but

of colors which are confused with gray by persons

who have any of the principal @es of defective

color vision. These colored dots are arranged in

any quadrant of the plate. A single test plate carries one or two of these

dots, like the background

symbols. The colored

dots, vary in size and

3
shades. In successive plates these symbols are

presented in graded steps of chroma.

Two general types of color vision deficiencies

are classified by the H-R-R—red-green deficiencies, which comprise most congenital color vision

deficiencies, and the much rarer blue-yellow deficiencies. The H-R-R further distinguishes three

subtypes of red-green deficiencies, protan, deutan, and “red~green undetermined.” The particular errors made on”the plates determine the classification.l’g’1 4’17 Protan deficiencies are characterized by decreased sensitivity for red and its

complementary hue, blue-green. These colors.

appear as gray or as an indistinct grayish color

to the individual with a protan-type deficiency.

Deutan is the term given to the decrease in

sensitivity for pure green and its complementary

hue, red-purple. These colors are seen as gray

or as an indistinct color close to gray by persons

with deutan-type deficiencies. Persons whose

red-green deficiency could not be classified as

protan or deutan are assigned the diagnosis “redgreen deficiency undetermined as to type.” Blueyellow deficiencies are classified by the H-R-R

as tritan or tetartan or as “blue-yellow deficiency

‘ undetermined as to type.” Tritan and tetartan

deficiencies indicate loss of sensitivi~ in the

blue-yellow perceptual area. To the tritan there

is confusion of yellow-green with gray, and for

the tetartan blue or yellow is confused with gray.

The H-R-R test is also designed to provide

a measure of the degree of deficiency through

its graded series of plates in which there is an

increasing saturation of the critical hues. Three

degrees of severity of defect are recognized in

the H-R-R-mild, medium, and strong. The classification is based on the last group of plates in

which errors occur. Only a rough quantification

of the degree of defect can be made in this manner, and it is recognized that pseudoisochromatic

plates do not reliably distinguish among other

classifications of color vision deficiency such as

“anomalous trichromats” or “dichromats.’’11811919

Evaluations of the Hardy -Rand-Rittler test

indicate that it is a reliable technique for screening normals and abnormals and for providing

qualitative diagnoses of red-green color vision

deficiencies.10 !12~16The test has also been favorably evaluated as a technique for quantitative

diagnoses of red-green defects. 13’16The paucity

of individuals with blue-yellow defects has prevented validation of the plates designed to detect

the rare tritan and the controversial tetartan

form of defective blue-yellow vision.17

The first four plates in the H-R-R test are

demonstration plates. The next six plates make

up the screening series, followed by 14 plates

in the diagnostic series. Fourteen of “the test

plates are concerned with red-green deficiencies,

and six are devoted to the detection and the

qualitative and quantitative diagnosis of blueyellow defective.

Testing Methods

In the survey of youth, color vision testing

preceded the other vision tests. The tests were

performed binocularly with glasses or other corrective lenses on if the youth normally wore them.

Test books were placed on a table under a Macbeth Easel Lamp having an intensity of from 20-

28 foot-candles, as measured weekly by light

meter at the table level. This is the type of illumination and within the intensity range recommended by the authors of the H- R-R test for

valid testing. 17The Easel Lamp provides sufficient intensity of the desired quality so that a

small amount of extraneous light in the room will

not appreciably affect the results of the tests.

The youth was seated at the testing table so that

his eyes were kept about 30 inches from the test

book. Each youth was first administered seven

plates of the Ishihara test (plates 1, 2, 5, 8, 11,

14, and 16) as a screen to separate youths with

normal color vision from those with color vision

deficiencies. If the youth had difficulty identifying

the numbers on the plates he was asked to trace

the figure he saw with a small paint brush. Responses to each plate were entered on a special

recording form (appendix III).

Youths who correctly read the Ishihara plates

were classified as having normal color vision

and testing was terminated. Failure to correctly

read any one of the screening plates except plate

1, which was used as a demonstration plate, indicated the possibility of a color vision deficiency,

and the youth was then administered the HardyRand-Rittler test to ..--s&. L:- A,.G,.:. . . ..

The first four

administered first.

VW. lly 111s Ucllucllby .

plates of the H-R-R were

These plates are used for

4
demonstration purposes to acquaint the youth with

the symbols he will see in the subsequent plates.

Plates 1-6, the screening plates, were then

administered. The youth was asked the number of

colored symbols he saw, their shape, and their

location on the plates. A correct answer to all

three parts was required to receive credit toward a rating of normal color vision. Answers

were entered on the special recording sheets

(appendix HI).

If the youth gave the correct response for all

six screening plates, he was considered to have

normal color vision and no further testing was

done. This occasionally occurred after one or

more incorrect responses on the Ishihara plates.

Youths making one or more errors on the H-R-R

screening plates were then given the diagnostic

series to determine the specific type of defi ciency,

i.e., protan, deutan, etc., and severity of the defect, i.e., mild, medium, or strong. All qualitative and quantitative diagnoses in this report are

based on H-R-R protocol.

Quality Control

As in the children’s cycle, vision tests for

youths were administered by the survey staff examining dentist because that member of the survey

team had the time available. The effect of this

was to have these tests done by a professional

person who, once the necessary special training

had been given, was adept at administering the

tests. Each of the five examining dentists employed during the cycle was given training and

practice in vision testing techniques to insure the

consistency of the test results. Further practice

was obtained during the “dry runs” preceding the

start of the regular examinations at each of the 40

locations in which the mobile Health Examination

Centers were located. Testing equipment and illumination were checked periodically through the

cycle to verify that they were in good working

order and both met the required standards.

FINDINGS

Screening Results

An estimated 95.7 percent or 21.7 million

youths 12-17 years of age in the noninstitutional

population of the United States would have been

identified as probably having normal color vision

on the basis of screening test results from the

findings obtained on the shortened form of the

Ishihara test used in the Health Examination Survey of 1966-70. These were youths who were able

to correctly identify the characters, or indicate

their absence, on each of the six Ishihara plates

used in the survey examination (table 1). The

remaining 4.3 percent of the youths misread at

least one of the six Ishihara screening plates.

In addition a small proportion of these youths

passed the initial screening section of the HardyRand- Rittler color vision test, The latter test was

given all those missing at least one Ishihara

plate to determine the extent and severity of their

color vision defects. This group of “false positives” on the Ishihara was considered for analytical purposes to also have normal colbr vision.

(This group constituted less than 5 percent of the

youths who failed the Ishihara test and so only 0.2

percent of all youths examined.)

The screening findings for youths correspond

closely to those obtained for children from the

identical color. vision test battery used in the

Health Examination Survey of 1963-65 (figure

l).l In that survey, an estimated 95.2 percent of

the noninstitutionalized children aged 6-11 years

in the United States were determined to have

normal color vision on the basis of the Ishihara

screening and an additional 0.2 percent on the

basis of ;he subsequent H-R-R screening:

100

r

I

I

6789101112 1314151617

AGE

Figure 1. Percent of boys with normal color vision, by age:

United States, 1963-70.

5
Distributions of scores (number of plates

read correctly) on the Ishihara plates for youth

by ageand sex are shown intable 2. No evidence

of a pattern between age and performance on the

plates is apparent. At all ages boys were much

more likely to have misread one Ishihara plate

or more than were girls, the difference exceeding the 99 percent confidence limit for these survey findings. Boys who failed the Ishihara screening test were substantially more likely .to have

missed at least five of the six plates than fewer;

while girls with some evidence of color deficiency were about as likely to have missed only

one than more than one plate, reflecting the

greater severity of the de~ect,. among boys.

H- R-R screening score. distributions are

presented in table 3 for the 4.3 percent of the

youth who failed the Ishihara and were administered this test. The number of girls in the group

was too small to provide reliable estimates for

them by single years of age. The distribution of

“false positives” on the Ishihara is indicated in

the table by those who read all six H- R-R screening plates correctly.

Prevalence findings of defective color vision

in the remainder of this report are based on the

H-R-R test protocol. Values for incomplete test

results were imputed by the method outlined in

appendix L

Prevalence

The estimated prevalence rate of defective

color vision among noninstitutionalized youths

12-17 years of age in the United States based on

findings from the Health Examination Survey was

4.1 percent; this delimits a population of approximately 934,000 youths with defective color vision

(table A). This percentage is comparable to the

3.8 percent estimated for children with color deficiencies (those 6-11 years of age in 1963-65).

Sharp differences were apparent in the prevalence rates for boys and girls. Boys were more

than 12 times as likely to have defective color

vision than were girls. More than 7.5percent of

the boys were found to have such a deficiency, but

only 0.6 percent of the girls were similarly affected (table 4).

Racial differences in the prevalence of color

vision deficiencies were negligible. The prevalence rate was slightly larger among white than

Table A. Prevalence rates for defective

color vision among youths 12-17 years,

by race and sex: United States, 1966-70

=I=I==E’

Both sexes ---- I 934 I 4.12

1

Boys ----------

~

White --------------- 767 7.72

Negro --------------- 95 6.35

Other races --------- 3 5.34

Girls ---------

k

69 0.62

White --------------- 67 0.70

Negro --------------- 2 0.15

Other races ---------

Negro boys or boys of other races. However, the

differences in the rates were not statistically significant at the 5-percent probability level. The

number of youths of other races in the population

is too small to provide reliable estimates, of the

prevalence of this defect for them from the present study. Similarly the prevalence of color deficiency among girls is so low that the estimates

for both the Negro and other racial groups are

not reliable and are presented only to indicate

that the rate among Negro girls is low.

Type of Deficiency

The most common perceptual color vision

deficiency found for kcth boys and girls was of

the red-green type. A small percentage of youths

did exhibit a combination of red-green and blueyellow perceptual defects (less than 1 percent),

but none of the surveyed youths failed to correctly

identify only the H-R-R blue-yellow screening

plates.

Racial differences with respect to the type

of color vision defect among boys were not apparent. A slightly larger proportion of white than

Negro boys did have a red-green deficiency while

slightly more Negro boys had a combination of

6
red-green and blue-yellow perceptual deficiencies, but in neither case were the differences in

rates statistically significant.

Boys were substantially more likely than

girls to have only a red-green deficiency than a

combination of red-&reen and blue-yellow perceptual defects. The ratio of these defects among

boys was nearly 8 (with only red-green) to 1

(with both types) compared with nearly 2 to 1

among girls.

Red-Green Deficiencies

An estimated 7.5 percent of the lmys in the

United States, ages 12-17, have a red-green color

vision deficiency alone or in combination with a

blue-yellow defect. A smaller proportion of Negro

boys exhibited a red-green deficiency than did

white boys, but the percentages were not significantly different (figure 2 and table 5).

The contrast in the proportions of red-green

deficiencies between boys and girls is striking.

Among white youths, 11 times as many boys were

affected as were girls. The difference in the rates

for Negro boys and girls for this perceptual deficiency is even greater.

No consistent age-related trend is evident

in the proportion of boys with a red-green visual

defect across the entire age range from 6-17

years (in the surveys of 1963-70). The prevalence of red-green deficiency was relatively conWhite Negro

Figure 2. Prevalence of red-green color vision defects among

white and Negro boys and girls 12-17 years: United States,

1966-70.

8 —

6 —

4 —

2 —

o_

6789101112 13 14 15 16 17

AGE

Figure 3. Prevalence of red-green color vision defects among

boys, by age: United States, 1963-70.

sistent for ages 8 through 17 (figure 3). The only

substantial difference occurred between the ages

of 7 and 12 years.

Severity of Deficiency

The H-R-R protocol provides for grading

into three severity categories: mild, medium, and

strong. Using this protocol, the proportion of

youths with a mild red-green deficiency was

slightly greater than for those with a medium defect which in turn slightly exceeded the proportion with a strong defect (table 6). Only the differences in the proportions between the mild and

strong groups are large enough to be statistically

significant. This pattern was not found among

children. For them proportions in the mild and

strong severity categories were identical while

relatively, slightly fewer were rated as medium

(figure 4). Although children and youths exhibited

different patterns of red-green severity, the differences between the respective proportions in

the severity classes for the two age groups are

not statistically significant.

White boys were more likely than Negro boys

12-17 years of age to have a red-green visual

defect. Among those with defects of medium or

strong severity the differences between white and

Negro are negligible: The consistent decrease in

7
Figure 4. Severity of red-green color vision defects for children

and youths 6-17 years: United States, 1963-70.

the prevalence of this red-green visual deficiency

with the increase in severity is evident among

white boys similar to the pattern for all boys 12-

17 years of age. Only the difference in the prevalence rates between the mild and strong defects

are statistically significant (figure 5 and table 6).

Among Negro boys 12-17 years about the same

proportion was found to have a mild or medium

defect and somewhat more (but not significantly

more) had a strong deficiency.

The prevalence of mild red-green perceptual deficiency among white girls was significantly greater than defects of medium severity,

while none were found to have strong deficiency.

Only mild red-green deficiencies were found

among Negro girls. As previously indicated, the

prevalence of color deficiency among girls was

:..,,

Negro

Mild Medium Strong

SEVERITY

Figure 5. Severity of red-green color vision defects a-g white

and Negro youths 12-17 years, by race: United States,

1966-70.

too low to provide consistently reliable national

estimates for them by race with the size and

design of the sample used in this survey.

Subtype of Red-Green Deficiency

The deutan subtype of red-green color vision

defect (decreased sensitivity for green) is the most

prevalent type of color vision deficiency among

boys. It was found among 4.1 percent of those 12-

17 years of age in this country. Over half of the

boys with defective color vision had this type of

problem (table 7). Protan defects (decreased

sensitivity for red) were less than half as prevalent among boys as the deutan type (1.7 percent

compared with 4.1 percent) and just slightly less

frequently found than the undetermined types of

red-green deficiency (1.8 percent).

The prevalence rates of protan and deutan

deficiencies among Imys 12-17 years of age were

similar to the corresponding rates among younger

lmys 6-11 years from the 1963-65 survey (2.2

and 3.8 percent, respectively) (figure 6). However, the proportion of boys with red-green deficiencies of undetermined type were significantly greater among youths than children (1.8

compared with 0.9 percent). This was due to the

significantly greater proportion of this type of

deficiency found among the older white boys (12-

17 years old) than those of 6 to 11 years.

As among the younger girls 6-11 years of

age in the 1963-65 survey, more than two-thirds

EEzlChildren 6.11 Pam

m Youths 12-17 years

Protan Deutan Undetermmed

TYPE OF DEFECT

Figure 6. Type of red-green color vision defect among children

and youths 6-17 years: United States, 1963-70.

8
Protan Deutan

TYPE OF OEFECT

Undetermined

Figure 7. Type of red-green color vision defect among white

and Negro youths 12-17 ‘years: United States, 1966-70.

of the girls 12-17 years old with a color vision

deficiency had one of undetermined red-green

type. Less than 1 percent of either age group had

defective color vision of any type.

The prevalence rates of all three types of

red-green color deficiency were similar among

white and Negro boys aged 12-17 years (figure

7). However, Negro boys of this oage were less

likely than white boys to “have a protan deficiency

of medium severity or a mild deutan deficiency

but more likely to have a strong deutan deficiency.

Red-Green Deficiencies by

Selected Demographic Variables

Only boys were considered in the analysis of

red-green deficiencies by demographic variables

because of the small number of affected girls.

The prevalence estimates for the latter group

will, consequently, be less precise but are included in the detailed tables 8-10 with their associated standard errors to convey the overall

picture obtained from the national survey of

youth.

Region— No significant pattern of regional

differences was found in the prevalence of color

vision deficiency among boys 12-17 years of age

in this country. The prevalence rates of .redgreen deficiencies among boys ranged from a low

of 6.3 percent in the Midwest to a high of 9.1

percent in the West. The difference in these rates

is not statistically significant at the 5-percent

probability level (table 8). The prevalence of this

condition among white and Negro boys was similar

in each of the regions except in the South where

the rate among white boys is significantly greater

(three times as large) as among Negro boys.

These regional findings are similar to those among

children 6-11 years of age in the 1963-65 survey.

?%ce oj residence—Youths (boys) living in

urban communities generally had a higher prevalence rate of red-green perceptual color vision

deficiencies than those boys living in rural areas

(table 9). This is the reverse of findings among

children 6-11 years of age in the 1963-65 survey, but the differences in rates are not significantly different either between surveys or between urban and rural residents in the present

study .

The estimated proportions of red-green color

deficiencies among boys living in areas of differing population size were found to range from a

high of 10.7 percent in cities of 250,000 to 1 million population to a low of 3.0 percent in places

with 10,000-24,999 population outside a Censusdefined “urbanized area.” Even though the difference between these two rates is substantial,

care must be taken in concluding that they are in

fact different. The coefficient of variation of the

smaller estimated proportion is sufficiently large

to cast doubt upon its reliability. Hence, caution

should be used in concluding that significant differences in the proportions of affected boys exist

between cities of differing size. Racial differences

in the prevalence of color deficiency were not

evident between white and Negro boys from either

urb~ or rural areas.

Family income—The prevalence ofred-grken

_-—

deficiencies did not vary consistently with the

level of family income. The percentage of boys

affected does not differ significantly across all

family income levels (table 10). The trend of a

slight increase in the prevalence of red-green

deficiencies by family income observed among

children was absent among youth. There were no

significant differences in the prevalence rates

across family income levels between youths 12-

17 years of age in the present study and children

6-11 years of age in the 1963-65 survey.

9
Blue-Yellow Deficiencies

All the youths diagnosed. as having a blueyellow deficiency on the Hardy -Rand-Rittler test

plates also had an accompanying red-green deficiency, as previously indicated. An estimated

0.6 youths per hundred 12-17 years of age in the

United States had this blue-yellow deficiency in

the period 1966-70. Almost all of these perceptual color vision defects (97 percent) were diagnosed as the undetermined subtype. The majority were of mild severity (88 percent). Perceptual blue-yellow deficiencies of mild severity

also predominated in the survey of children (83

percent) (appendix IV).

Combined Red-Green and

Blue-Yellow Deficiencies

A somewhat larger proportion of youths

(0.56 percent) were found to have perceptual

difficulties in both red-green and blue-yellow

areas than were observed in the survey of children (0.32 percent). The difference probably reflects sampling variability and is not statistically

significant at the 5-percent level (table 11).

The prevalence rate for white Imys with this

combination of perceptual color defects was estimated at 0.86 per hundred and was about 0.25

per hundred for white girls. The rates for Negro

youths are similar to those found for white youths

but are far less reliable. Appendix IV contains

further information on the specific combinations

of red-green and blue-yellow deficiencies found

among the surveyed youths.

Agreement on Reexamination

The Health Examination Survey among youths

in 1966-70 utilized the same sampling areas and

housing units as the previous Health Examination

Survey among children in 1963-65. As a result

nearly one-third of the youths in the present

study had also been examined in the children’s

survey. The time lapse between the two examinations ranged from 28 months to 5 years with a

median time lapse of about 4 years. Since the

color vision tests were identical in both surveys,

some longitudinal data on these deficiencies were

available for an estimated 7.4 million youths.

Comparison of the findings at these two points in

time will probably reflect the reliability of the

tests used as well as any change in the condition

of the children. This subgroup, however, cannot

be considered typical of the total group of youths

since they will be limited to the group who remained in the same location during that period of

time and were willing to be examined again.

The prevalence of red-green color vision deficiencies among youths (both sexes) who had also

been examined as children was 3.7 percent. This

is slightly (but not significantly) lower than the

rate of 4.1 percent for all youths. Among both

boys and girls the rate of defective color vision

found on reexamination at ages 12-17 years was

slightly lower than it had been for them when they

were examined as children (6-11 years of age).

The rate for the boys in the longitudinal group

was 6.9 percent compared with 7.5 percent for

all boys aged 12-17 years. Consideration of the

comparability of the color vision test results

from the two examinations will be limited here

to the boys, since the number of girls with such

defects is too small to provide reliable estimates

for them.

About two-thirds (64 percent) of the boys with

red-green color vision deficiencies had been

found to have the same type in the earlier survey

and there was agreement on both strength and

type of defect for 42 percent (table 12). For the

remaining 21 percent where there was agreement

on the type of defect but the strength of the defect differed, the deficiency was more likely

than not to be weaker in the older age group than

when they were children (19 percent).

Among the remaining 36 percent whose type

of deficiency differed, the shift between childhood and youth was. slightly more likely to have

been from a definite decreased sensitivity for

red or green to an undetermined type (13 percent) than from an undetermined type to a more

definite defect (10 percent) or from a predominately decreased sensitivity for red to one for

green (10 percent).

COMPARISON WITH

OTHER STUDIES

Defective color vision, or color blindness

as it is commonly known, has attracted the attention of scientists since its discovery in the

10
Table B. Selected studies reporting prevalence of red-green color vision deficiencies

Male

ReferFemale

Author and year ence Population

No.

Test used

Rate

N~be= P%foo Nmber per 100

European studies

Waalcr, 1927 23 Norwegian students 9,094 8.01 9,072 0.44 Ishihara and anomaloscope

Von Planto, 1928 24 Swiss students 2,000 7.95 3,000 0.43 Isbihara and anomaloscope

Wicland, 1933 25 Swiss students 1,036 8.2

Schmidt, 1936

Ishihara and anomaloscope

26 Germany 6,863 7.75 5,604 0.36 One setting of anOma10-

scope

Vernon and Straker, 1943 27 British males 12,344 7.25 - A-O Pseudoisochromatic

Plates

GZiCV12 , 1946

.—— -

28 British Air Force aircrew

candidates 16,180 6.63 - Ishihara

IJrancoisand others, 1957 29 Belgian schoolboys 1,243 18,61 - Ishihara, anomaloscope

and Farnsworth Tritan

Plate

Mm, 1956 30 Australia 558 7.3 327 0.6 Ishihara

KIw$rumianand Pickford, 1959 22 France 6,635 S.95 6,990 0.50 Ishihara

Brown, 1951 31 Scottish students 525 7.43 252 0.46 Ishihara

Crone, 196S 32 Netherlands 3,167 7.95 3,359 0.45 Ishihara, H-R-R, and

others

U,S. studies

Hcqt , 1922 33 Baltimore, Maryland, school

children

crocks, 1936 37 Negroes, Virginia

Swcuncy nnd-~thers, 1964 38 Negro boys in New York City

Thulinc, 1964 14 Students in Tacoma,

Washington

Slmrran, 1965 39 Students in Tennessee

White

Negro

LI.S. HcxllthExamination Sur-

—

\,lJy,1963-65 40 Representative nationwide

s3mple of children 6-11 years

of age in the noninstitutional

population of the United

States

White

Negro

L1.S, Wualth Examination SurVOY, 1966-70 Representativenationwide

sample of children 12-17 years

of age in the noninstitutional

population of the United

States

White

Negro

‘Includes red-green and other defects.

448

1,286

795

538

205

118

2,019

1,137

5,263

676

548

128

3,153

k64

3>047

479

7.8

S.2

S.4

3.9

::2

3.9

6.77

2.99

6.14

5.67

6.83

3.12

7.36

4.04

7.72

6.35

I

487 1.6

==1=

=

496 0.s

722 0.1

-+---=-

%--l+

-4=

I

1

+

2,947 0.50

523 0.77

2,688 0.70

520 0.15

Nela Test (coloredwool

skeins) ‘

Ishihara

Ishihara

Ishihara

Ishihara

Screened by H-R-R

Screened by anomaloscope

Ishihara and H-R-R

H-R-R

Ishihara and H-R-R

Ishihara and H-R-R
late 18th century .20 Many surveys of color vision

have been conducted, most performed outside the

United States and most utilizing testing instruments and procedures somewhat different from

those of the Health Examination Survey. Reviews

of these studies appear in articles by Post,

Kherumian and Pickford, and Kalmus.20-22 General findings from some of these studies are

@esented in table B for comparison with national

estimates for American youth from the present

study. The list of earlier studies in table B is

not exhaustive. The studies selected for comparison were primarily based on large-scale testingperformed on subgroups of white European or

American populations or American Negro populations. Most utilized the Ishihara test or the

H-R-R. A few also employed the anomaloscope,

a precise instrument for determining defective

color vision. In most cases findings are presented

only for red-green color vision deficiencies.

Findings from the present survey agree in

part with those of other major studies. The prevalence rates for red-green deficiencies among

white males in Europe and the United States, reviewed by Post, are near 8 percent.21 The 7.7

percent prevalence rate found for white American boys 12-17 years of age from the present

study approximates this figure, The rate for

white girls (0.7 percent) is much higher than that

found among 5,078 Tacoma, Washington, schoolgirls. 14However, it is not significantly larger than

the prevalence rate found for white girls in the

survey of children. conducted by the Health Examination Survey during 1963-65.40

The national prevalence rate estimated for

Negro boys screened on the HZ}-R plates is essentially that found by Sweeney and others among

Negro boys in New York City. The rate for American Negro girls in the present study agrees with

Crooks’ 1936 findings in Virginia.37 It does not

agree with findings among children from the

1963-65 Health Examination Survey. The difference between the two rates found in the surveys

of children and youth is most probably due to

sampling variability; the coefficient of variation

for the prevalence rate of red-green deficiency

among Negro girls in the present survey is high

and the statistic is unreliable.

The estimated 0.56 percent of the youths in

the United States who exhibited evidence of blueyellow color vision deficiencies is larger than

previous estimates by Wright~3 Thuline}4 and

others}2~41 It is not significantly larger than the

rate estimated for American children by the

Health Examination Survey. Most of the cases in

the present survey were of the mild blue-yellow

undetermined type and all had accompanying redgreen defects.

A preponderance of males over females with

red-green deficiencies has been observed inmost

studies of white populations.

The finding from this study of no statistically

significant relationship of color vision defects with

age among American youths within the age range

of the population studied is in accord with earlier

studies & Chapanis and Thuline. 1A~1~

SUMMARY

national estimates based on Health Examination Survey findings from a probability sample

representative of youths 12-17 years of age in the

noninstitutional population of the United States

show:

1.

2.

3.

4.

About 4.1 percent or 934,000 youths were

found to have color vision deficiencies.

Boys were about 12 times as likely to

have this condition as girls. Over 7,5 percent of the boys showed evidence of a

color vision deficiency while only 0.6 percent of the girls were similarly affected.

There were no significant differences in

the prevalence rates for white and Negro

boys.

Red-green color vision deficiencies were

substantially more prevalent than blueyellow defects. Red-green defects only

affected 6.6 percent of boys and 0.4 percent of girls.

No significant differences were found between white and Negro boys with respect

to the prevalence rates of red-green color

deficiencies.

Age did not appear to be significantly

related to the prevalence of color vision

deficiencies.

12
5. Red-green deficiencies in girls were more

frequently of the mild type, while among

boys the cases were more evenly distributed by severity.

6. Deutan-type defects (decreased sensitiv- 8.

ity to green) occurred with the greatest

frequency among boys (4.1 percent of all

boys),

7. No statistically significant regional differences in the prevalence of red-green

deficiencies were found among boys, alREFERENCES

1Linksz, A,: An Essay on Color Vision and Clinical color

L’ision Tests. New York. Grune and Stratton, 1964.

2Du!ie-Elder, W, S.: Parson’s Diseases of the Eye, 14th ed.

Boston. Little, Brown and Company, 1964.

3Nation.l Center for Health Statistics: Origin, program

and operation of the U.S. National Health Survey. Vital and

Hdth Statistics. PHS Pub. No. 1000-Series l-No. 1. Public

Health Service, Washington. U.S. Government Printing Office,

Aug. 1963.

4National Center for Health Statistics: Plan and initial

program of the Health Examination Survey. Vital and HeaWr

St~tistics, PHS Pub, No, 1000-Series l-No. 4. Public Health

.%rvice. Washington. U.S. Government Printing Office, July

19650

5 Nation~ Center for Health Statistics: Cycle I of the

Health Examination Survey, sample and response, United

States, 1960-1962. Vital and Health Statktics. PHS pub. No.

1(300-Series 1l-No. 1. Public Health Service. Washington. U.S.

Government Printing Office, Apr. 1964.

6National Center for Health Statistics: Plan, operation,

and response results of a program of children’s examinations.

I’ital wrd Health Statistics. PHS pub. No. 1000-Series l-No. 5.

Public Health Service. Washington. U.S. Government Printing

Off~ce, Oct. 1967,

7National Center for Health Statistics: Plan and operation

of a Health Examination Survey of U.S. youths 12-17 years of

W. ~’ttul and Heaklt Statistics. PHS pub. No. 10rIO...SeneS

1-No. 8. Public Health Service.” Washington. U.S. Government

Printing Office, Sept. 1969.

8 National Center for Health Statistics: Visual acuity of

children, Vihd and Health Statistics. PHS Pub. No. 1000-Series

11-No. 101. Public Health Service. Washington. U.S. Government Printing Office, Feb. 1970.

9Ishihara, S.: The Series of Plates Designed as a Test for

(hlonr-~lindness. Tokyo. Kanehara Shuppan Co., Ltd., 1960.

though a significant racial difference was

observed in the South. Differences in the

prevalence rates across income levels

were negligible.

Blue-yellow deficiencies were found in an

estimated 0.6 percent of the youth population and only in conjunction with a redgreen defect. This combination of perceptual defects affected about 0.9 percent of

the boys and 0.2 percent of the girls. Most

blue-yellow defects were of the mild undetermined type.

1‘Schmidt, L: Comparative evahration of the Hardv-

.

Rand-Rit tier Polychromatic Plates for testing color vision.,

Technical Report, Project No. 21-31-013. U.S. Air Force

School of Aviation Medicine, June 1952,

11Sloan, L., and Habel, A.: Tests for color vision deficiency based on the pseudoisochromatic principle. A.M.A.

Arch. ophthalmol. 55(2):229-239, Feb. 1956.

12Walls, G.: How good is the H-R-R Test for color blindness? Am. j. Optom. 36(4):169-193, Apr. 1959.

13Crone, R. A.: Quantitative diagnosis of defective color

vision. Am. ‘J. ophthalmol. 51:298-305, Feb. 1961.

14Thuline, H. C.: Color vision defects in American school

children. J.A.M.A. 142-146, May 1964.

15Nakajima, A., Ichikawa, H., Nakagawa, 0., Majima, A.)

and Watanabe, M.: Ishihara Test in color-vision defects. Am. j.

ophthalmol. 49:921-929, 1960.

16

Rand, G., and Rittler, M. C.: An evaluation of the

AO H-R-R Pseudoisochromatic Plates. A.M.A. Arch. Ophthalmol. 56(5):736-742, 1956.

lTHardy, L. H., Rand, G., and Rlttler, M. C.: AO H-R-R

Pseudoisochromatic Plates, 2d ed. American optical Company,

1957.

18Cavanagh, P.: The Ishihara Test and defects of colour

vision. Occup. Psychol. 29:43-57, 1955.

19Wright, W. D.: Researches on Normal and Defective

Colour Vision. St. Louis. Mosby, 1947.

20K~mus, H.: Diagnosis and Genetics of Defective Cobr’

Vision. oxford and New York. Pergamon Press, 1965.

21post, R. H.: Population differences in red and green

color vision deficiency. Eugerz. Q. 9:131-146, 1962.

22 Khemm~n, R., and Pickford, R. W.: Heredit~ et Frequence des Dyschromatopsies. Paris. Vigot Freres, 1959.

13
23Wa~er, Go H. M,: ijber die Erblichkeitsverhdtnisse der

verschiedenen Arten von angeborener Rotgrunblindheit. Z.

indukt. abstamm. -u. Vererb. Lehre 45:279-333, 1927.

24von Planta, P,: Die H5ufigkeit der arrgeborenen

Farbensinnst&ungen bei Knaben und Madchen und ihre

Fest st ellung durch die iiblichen klinischen proben. V.

Graefes Arch. Opkthalmol. 120,253-281, 1928.

25Wieland, M,: Untersuchungen uber Farbenschwache bei

Konduktorinnen. V. Graefes A rc h. Ophthalmol. 130:441,

1933.

26 Schmidt, I.: Ergebnis einer Massenuntersuchung des

Farbensinnes mit dem Anomaloskop. Z. Bahnartze 31:44,

1936.

27vernon, p. E., and Straker, A.: Distribution of colorblind men in Great Britain. Nature, London. 152:690, 1943.

28 Grieve, J.: Incidence of defective co]our vision. Nature,

London, 157:376, 1946.

29 Francois, J., Verriest, G., Mortier, V., and Vanderdonck, R.: De la &&quence des dyschromatopsies

congenitales chez l’homme. Ann. OCU1.190:5-16, 1957.

3 OMann, 1,, and Turner, C.: color vision ~ native races in

Australasia. Am. J. ophthalmol. 41:797-800, 1956.

31 Brown, “R.: An investigation into the colour.vision of

school children. R-. j. Educ. Psychol. 21:150-153, 1951.

32 crone, R+ A.: Incidence of known and unknown

colour-vision defects. ophthalmolog”cu (BaseU 155:37-55, 1968.

33 Haupt, I.: The Nela test for color blindness applied to

school children. ]. Comp. PsychoL 6:291-302, 1926.

34~des, w.: 100 cases of color blindness detected with

the Ishihara test.]. Gen. psychol. 2:535-543, 1929.

35Clements, F.: Racial differences in colour vision. Am, j,

phys. Anthropol. 14:417-432, 1930.

36 Garth, T, R.: The incidence of color blindness among

races. Science. 77:333-334, 1933.

37Crooks, K, Be M,: Further Obsewations on color blind.

ness among Negroes, Hum. Biol. 8:451-458, 1936,

38 Sweeney, D. R., Zegers, R. T., and Collins, W. E.: Color

blindness in male Negro children. ]. Sot. Psychol. 62:85-91,

1964.

39Shearron, G. F.: Color vision deficiency in primary

school children. Sight Sau. Rev, 35:148-151, 1965,

4ONationd Center for Health Statistics: Color Vision Deficiencies in children. Vital and Heakh Statistics. Series 1 l-No,

118. DHEW Pub. No. (HSM) 73-1600. Health Services and

Mental Health Administration. Washington. U.S. Government

Printing”Office, Aug. 1!372.

4 Ipickford, R. W.: Individual Differences in Colotlr vision. New York. MacMfllan, 1951.

42Chapanis, A.: Relationships between age,. visual acuity,

and color vision. Hum. Biol. 22:1-33, Feb. 1950.

43Wright, W. D.: The characteristics of tritanopia. j. Opt.

Sot. Am. 42:509-521, 1952.

000
LIST OF DETAILED TABLES

Table 1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

Number and rate per 100 youths by screening results of color vision test, age,

and sex, with standard errors for totals: United States, 1966-70----------------

Percent distribution of Ishihara screening scores for youths by age and sex,with

standard errors for totals: United States, 1966-70------------------------------

Percent of youths with color vision defects on Ishihara test and percent distribution of their Hardy-Rand-Rittler screening score by age and sex, with standard

errors for totals: United States, 1966-70---------------------------------------

Prevalence rate per 100 youths 12-17 years showing color vision status, from the

Hardy-Rand-Rittler test, by race and sex, with standard errors: United States,

1966-70-------------------------------------------------------------------------

Prevalence rate per 100 of red-green color vision deficiencies among youths, by

race, age, and sex, with standard errors: United States, 1966-70----------------

Prevalence rate per 100 of color vision defects among youths 12-17 years, by

severity of defect, race, and sex, with s“tandarderrors: United States, 1966-70-

Prevalence rate of red-green color vision deficiencies among youths 12-17 years,

by type and severity of defect, race, and sex, with standard errors: United

States, l966-7O--------------------------------------`---------------------------

Prevalence rate per 100 of red-green color vision deficiencies among boys and

girls 12-17 years, by race and geographic region, with standard errors: United

States, 1966-70-----------------------------------------------------------------

Prevalence rate per 100 of red-green color vision deficiencies among boys and

girls 12-17 years,by race and population size of place of residence, with standard errors: United States, 1966-70----------------------------------------------

Prevalence rate per 100 of red-green color vision deficiencies among boys and

girls 12-17 years,by race and family income,with standard errors: United States,

1966-70-------------------------------------------------------------------------

Prevalence rate per lOOof color vision deficiencies involving both red-green and

blue-yellow perception among youths 12-17 years, by race and sex, with standard

errors: United States, 1966-70--------------------------------------------------

Percent distribution of type and severity of defective color vision among boys

12-17 years by type and severity of color vision defect for them as boys 6-11

years and population estimates for those with defective color vision both as

children and as youths: United States, 1963-70----------------------------------

Yage

16

17

18

19

20

21

22

23

24

25

26

27

15
Table 1. Number and rate per 100 youths by screening results of color vision test,age, ~

and sex, with standard errors for totals: United States, 1966-70

Sex and age

Both sexes

12-27 years-----------------------------------

12-17 years------------------------------------

12

13

14

15

16

17

12

13

14

15

16

17

Boys

12-17 years------------------------------

years--------------------------------------

years---------------------------------------

years---------------------------------------

years---------------------------------------

years---------------------------------------

years---------------------------------------

Girls

12-17 years------------------------------

years---------------------------------------

years--.------------------------------------

years---------------------------------------

years---------------------------------------

years--------------------------------------

years---------------------------------------

Both sexes 12-17 years------------------------

Boys 12-17 years------------------------------

Girls 12-17 years------------------------------

All

youths

.,

Failed Ishihara

““am

Number in thousands

22,692 II 21,714I 934 I 44

Percent

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

.*.

.*.

...

95.69

92.26

91.44

93.02

92.92

91.63

91.91

92.69

99.20

99.27

99.06

98.97

99.10

99.56

99.28

4.12

7.53

8.43

6.78

6.81

8.05

8.09

6.97

0.62

0.73

0.63

0.61

0.90

0.28

0.54

Standard error

0.38

0.71

0.20

0.19

0.21

0.13

0.20

0.27

0.33

0.34

0.18

0.31

0.41

0.16

0.18

0.35 0.07

0.68 0.07 ‘

0.14 0.10

16
Table 2. Percent distribution of Ishihara screening scores for youths by age and sex,

with standard errors for totals: United States, 1966-70

Sex and age

Both sexes

12-17 years-----------------

12

13

14

15

16

17

12

13

14

15

16

17

Boys

12-17 years---------years--------------------

years--------------------

years--------------------

years--------------------

years--------------------

years--------------------

Girls

12-17 years-----------

years--------------------

years--------------------

years--------------------

years--------------------

years--------------------

years--------------------

Both sexes 12-17 years------

Boys 12-17 years------------

Girls-----------------------

II Number of Ishihara plates read correctly

.

Total 6 5 4 3 2 1 0

Percent distribution

100.0

100.0

100● o

100.0

100.0

100.0

100.0

100.0

100.0

100.0

100.0

100.0

100.0

100.0

100.0

. . .

● *.

. . .

95.69

92.26

91.44

93.02

92.92

91.63

91.91

92.69

99.20

99.27

99.06

98.97

99.10

99.56

99.28

0.38

0.42

0.70

0.36

0.24

0.26

0.19

0.77

0.34

0.33

0.65

0.27

0.15

0.16

0.45

c

“ k.

0.41

0.73

0.64

0.76

0.52

0.89

0.36

1.25

0.08

0.10

0.11

0.16

0.12

mdarc

0.50

0.87

1.40

0.85

1.20

0.51

0.76

0.45

0.12

0.14

0.17

0.15

0.27

zrror

0.55

0.96

0.72

0.99

0.71

1.47

1.31

0.61

0.13

0.15

0.27

0.19

0.13

0.10

0.18

0.07

1.84

3.50

4.13

3.34

3.44

4.02

3.43

2.55

0.13

0.34

0.44

0.24

0.47

0.06

0.63

1.24

0.97

0.68

0.97

1.23

2.05

1.69

.

0.11

0.21

17
Table 3. .Percentof youths with color vision defects on Ishihara test and percent distribution of their Hardy-Rand-Rittlerscreening score by age and sex, with standard

errors for totals: United States, 1966-70

Per- I 1[Number of H-R-R screening plates read correctly

sent

given Total

R-R-R 6 5 4 3 2 1 0

Sex and age

Both sexes

12-17 years---==-----

Percent distribution

4.31 100.oo 4.51 17.11 13.88 17.37 39.19 5.34 2.61

7.74

Boys

12-17 years----

years-------------

years-------------

years-------------

years-------------

years-------------

years-------------

LOO.00 2.71 16.58 13.89 18.05 $1.69 5.15 1.92

12

13

14

15

16

17

8.56

6.98

7.08

8.38

8.09

7.31

0.80

0.73

0.94

1.02

0.90

0.44

0.72

...

● ..

● ..

LOO.00

LOO.00

LOO.00

LOO.00

LOO.00

LOO.00

1.50

2.89

3.78

3.90

4.65

22.40

32.92

40.39

36.72

25.46

25.9%

11.51

7.63

11.80

13.57

28.36

22.37

30.92

34.17

15.14

37.98

14.84

19.34

12.95

12.90

13.92

8.92

13.75

11.79

31.82

37.27

6.16

16.55

21.45

19.50

24.75

22.56

10.57

49.28

29.72

$7.96

37.82

$6.41

62.77

37.82

35.50

14.31

19.80

12.21

30.21

33.55

3.57

9.70

9.13

7.74

7.13

32.68

.

2.L9

7.78

.

2.19

9.47

20.70

37.27

Girls

12-17 years----

years-------------

years-------------

years-------------

years-------------

years-------------

years-------------

1.00.00

LOO.00

LOO .00

LOO.00

LOO.00

LOO.00

L,00.00

12

13

14

15

16

17

Both sexes 12-17

years---------------

BOYS 12-17 years-----

Girls 12-17 years----

Standard error

. . . 1.46

... 0.86

... 9.68

2.82 1.93 2.13

3.15 1.94 2.17

7.63 5.71 7.86

3.77

3.98

6.42

1.38

1.25

5.78

0.74

0.79

1.90

18
Table 4. Prevalence rate per 100 youths 12-17 years showing color vision status from

the Hardy-Rand-Rittlertest, by race and sex, with standard errors: United States,’

1966-70

.

Race and sex

Both sexes

Total--------------------------

BoJw_

Total--------------------

White--------------------------

Negro--------------------------

Other races--------------------

Girls

Total--------------------

White.-------------------------

Negro-------.------------------

other races--------------------

Both sexes

Total------.-------------------

Boys

Total--------------------

White--------------------------.

Negro--------------------------

other races--------------------

Girls

Total--------------------

White-------------m------------

Negro--------------------------

other races--------------------

All

youths

100.0

-i

100.0

100.0

100.0

100.0

100.0

100.0

100.0

100.0

. . .

Defective color vision

Normal

color Redvision RedTotal

Blue- green

green yellow and

only only blueyellow

Percent

95.88

92.47

92.28

93.65

94.66

99.38

99.30

99.85

100.00

.*. II 0.35

.*. 1 0.68

. . . 0.65

.*. 2.58

... 5.50

● . . 0.14

4.12

7.53

7.72

6.35

5.34

0.62

0.70

0.15

3.56

6.65

6.86

5.33

5.34

0.39

0.45

Standard error

0.35

II :

0.29

0.68 0.56

0.65 0.56

2.58 1.77

5.50 5.50

0.14 0.14

w

,0.56

0.88

0.86

1.02

0.23

0.25

0.15

.-

0.13

0.25

0.24

0.88

0.05

0.07

0.13

w’”
Table 5. Prevalence rate per 100 of red-green color vision deficiencies among youths, I

by race, age, and sex, with standard errors: united States, 1966-70

Sex and age Total White

Both sexes

12-17 years----------------

12

13

14

15

16

17

12

13

14

15

16

17

4.12

Boys

12-17 years----------

L

7.53

years-------------------

years-------------------

years-------------------

years-------------------

years-------------------

years-------------------

8.43

6.78

6.81

8.05

8.09

6.97

Girls

12-17 years----------

L

0.62

years------------------- 0.73

years------------------- 0.63

years------------------- 0.61

years------------------- 0.90

years------------------”- 0.28

years------------------- 0.54

Percent

-4.26

7.72

8.93

7.11

7.02

8.44

7.79

6.95

0.70

0.85

0.74

0.71

0.91

0.33

0.62

3.22 2.92

6.35 5.34

5.51 -

5.03 -

5.67 -

4.39 26.45

10.60 -

7.47 -

0.15 -

- ‘-

0.95 -

EIEIEIE’

Standard error

0.35 0.34 1.28

0.68 0.65 2.58

1.53 1.61 4.25

‘1.11 1.32 1.53

1.12 1.13 2.65

1.51 1.66 2.00

1.47 1.17 6.94

1.29 1.55 4.77

0.14 0.17 0.13

0.35 . 0.41 -

0.34 0.39 -

0.32 0.38 -

0.41 0.46 0.85

0.20 0.23 -

0.53 0.61 -

3.33

5.50

.

22.53

20
Table 6. Prevalence rate per 100 of color vision defects among youths 12-17 years, by

severity of defect, race, and sex, with standard errors: United States, 1966-70

All redgreen

defects

Severity

Race and sex

Mild lMedium IStrong

Both sexes Percent

4.12 1.71 1.34 1.07

9

7.53 2.91

7.72 3.11

6.35 1.67

5.34 -

0.62 0.49

0.70 0.54

0.15 0.15

Boys

Total ---------------- -------- -------- ------ 2.51 2.11

2.63

1.62

5.34

White --------- ------------------------------------

Negro --------------------------------------------

Other races --------------------------------------

1.98

3.07

Girls

Total --------------------------------------- 0.13

White --------------------------------------------

Negro -------------- -------------- ------- -----------

Other races:-------------------------------------

0.15

Both sexes Standard error

Total --------- --------------------------- -------- 0.35 0.19 0.19 0.18

Bovs

Total -------- ---------------- -------- ------ 0.68 0.34 0.37 0.35

0.39

0.61

0.39

0.90

5.50

0.32

1.49

White -------- -.------ ---------------- -------- ----

Negro ------.- .--------------- -------- -------------

other races --------------------------------------

0.65

2.58

5.50

Girls

Total --------- --..--------------- ----------- 0.14 0.15 0.04

White ------------------ -------------------------- 0.17

0.13

0.17

0.13

0.05

Otiierraces --------------------------------------

21
Table 7. Prevalence rate of red-green color vision deficiencies among youths 12-17 years, by type and severity of defect, race. and sex, with standard errors: United States, 1966-70

All Protan I Deutan I Undetermined

ced-

;reen

de- Total ~ld Medi- Strong Total Mild MediFects Strong Total Mild Medium urn urn

Strong

Race and sex

Both sexes Percent

Total----------------- 4.12

7.53

7.72

6.35

5.34

0.62

0.84

1.66

0.16

0,32 T

0.28 0.40

0.$5 0.79

2.16 0.63 0.88 0.65 1.12 0.93 0.18 0.O1

0,02

-

Boys

Total----------- 4.08 1,11 1.68 1.29 1.79 1,48 0.29

I

White-----------------

Negro-----------------

Other races-----------

1.70

1.18

5.34

0.31

0.41

0.57 0.82

0.18 0.59

5.34 -

4.11

4.10

1.26

0.19

1.73

1.45

0.06

1.12

2.46

1.91

1.07

0.44

1.55

1.07

0.36

0.33

0.08

0.03

Total----------- 0.18 0.12

White-----------------

Negro-----------------

Other races-----------

0.70

0.15

0.35

0.68

0.22 0.15 0.07 0.48

0.15

0.12

0.39

0.15

0.09

0.15

0.31

0.36

0.51

5.50

0.15 0.01

Both sexes Standard error

Total-----------------

+

0.05 0.07 0.10

0.21

0.28 0.11 0.16 T

0.12 0.05

Boys

J

0.10 0.14

0.10 0.16

0.29 0.19

5.50

Total----------- 0.55 0.20 0.32 0.29 0.21 0.18 I 0.10 0,03

White-----------------

Negro-----------------

Other races-----------

0.65

2.58

5.50

0.14

0.23

0.35

0.51

2.07

0.05

‘0.23

0.19

0.04

0.04

0.35

0.74

0.04

0.22

1.48

0.24

0.56

0.14

();;

.

0.20 0.11

0.56 -

0.13 0.01

0.03

Girls

Total -----------

0.15 0.01

0.13 -

White -----------------

Negro -----------------

Other races-----------

0.17

0.13

. 0.06 0.05

22
Table 8. Prevalence rate per 100 of red-green color vision deficiencies among boys and

girls 12-17 years, by race and geographic region, with standard errors: United

States, 1966-70

Sex and geographic

region

WE

United States--------

Northeast ------------------

Midwest--------------------

South----------------------

West-----------------------

GL?d&

United States--------

Northeast------------------

Midwest--------------------

South----------------------

West-----------------------

Total

7.53

7.24

6.31

7.53

9.12

0.62

0.92

0.39

1.19

0.10

Percent

7.72

7.57

6.30

9.19

8.31

0.70

1.08

0.43

1.52

0.11

1

4.78 -

5.48 *

2.93 -

21.10 -

0.15 -

X0.31 -

rotal

0.68

0;81

1.77

0.87

1.96

0.14

0.32

0.31

0.30

0.13

White Other

Negro races

Standard error

0.65

0.83

1.84

1.08

1.44

0.17

0.36

0.34

0.38

0.14

2.58

3.22

2.48

0.77

10.36

0.13

0.28

*

*

.

23
Table 9. Prevalence rate per 100 of red-green color vision deficiencies am?ng boys and

girls 12-17 years, by race and population size of place of residence, With standard

errors: United States, 1966-70

Sex and population size

&w

Total urban----------

3,000,000 or more----------

1,000,000-2,999,999--------

250,000 to 999,999---------

Less than 250,000 in

an urbanized area---------

More than 25,000 not in

an urbanized area---------

‘1O,OOO to 24,999---------

2,500 to 9,999-----------

Rural----------------

GL&u

Total urban----------

3,000,000 or more----------

i,ooo,ooo.2,999,999--------

250,000 to 999,999---------

Less than 250,000 in

an urbanized area---------

More than 25,000 not in

an urbanized area---------

10,000 to 24,999---------

2,500 to 9,999-----------

Rural----------------

Percent

7.54

5.98

8.52

10.73

8.43

4.52

3.01

7.80

7.48

0.62

0.58

0.45

0.44

1.32

0.53

0.81

7.73

6.31

6.95

11.88

10.54

4.70

3.27

8.53

7.57

0.70

0.79

0.51

0.32

1.63

0.55

0.89

6.36

5.23

18.16

3.66

2.61

5.84

0.15

1.00

*

*

Standard error

0.68

0.36

3.08

1.47

4.74

2.32

3.54

2.60

1.08

0.14

0.37

0.27

0.31

1.18

0.54

0.19

0.65

0.58

2.31

1.23

5.58

2.39

4.09

2.78

1.14

0.17

0.50

0.31

0.35

1.51

0.57

.-

0.20

2.58

1.70

14.56

5.91

3.20

1.68

0.13

1.27

*

-’

*

.

24
,

Table 10. Prevalence rate per 100of red-green color vision deficiencies among boys and

~i&s7~2-17 years, by race and family income, with standard errors: United States,

Income and sex

Boys

All incomes----------

Less than $3,000-----------

$3,000-$4,999--------------

$5,000-$6,999--------------

$7,000-$9,999--------------

$10,000-$14,999------------

$15,000 or more------------

Unknown--------------------

Girls

All incomes----------

Less than $3,000-----------

$3,000-$4,999--------------

$5,000-$6,999--------------

$7,000-$9,999--------------

$10,000-$14,999------------

$15,000 or more------------

Unknown--------------------

7.53

7.57

5.11

9.65

6.39

9.82

7.70

5.14

0.62

0.78

0.58

0.36

0.91

0.68

0.27

0.43

Percent

7.72

7.65

6.14

8.72

6.42

10.06

7.90

5.83

0.70

0.95

0.79

0.42

0.97

0.71

0.28

0.51

6.35

7.44

2.43

I_4.48

6.73

2.98

0.15

0.45

*

L’otal

0.68

1.73

1.19

1.82

1.15

1.65

1.82

1.73

0.14

0.20

0.07

0.26

0.42

0.36

0.26

0.42

White Negro

Standard error

0.65

2.04

1.58

1.14

1.06

1.70

1.88

1.91

0.17

0.22

0.12

0.30

0.45

0.38

0.27

0.52

2.58

2.51

1.32

11.54

5.34

2.86

0.13

0.40

.

-

.

Other

races

*

*

,

25
Table 11. Prevalence rate per 100 of color vision deficiencies involving both redgreen and blue-yellow perception among youths 12-17 years, by race and sex, with

standard errors: United States, 1966-70

Sex Total White Negro Other

races

Percent

Both sexes-------------------------------- ●

Boys--------------------------------------------

Girls------------------.------.----------------- ii Em

Standard error

Both sexes-------------------------------- 0.13 0.13 0.44

Boys------------------------------------------- 0.25 0.24 0.88

Gi"rls------------------------------------------- 0.05 0.07 0.13

26
Table 12. Percent distribution of type and severity of defective color vision among boys 12-17 yeara by type and severity of color vision defect for them ss boys 6-11 years and population estimates for those with defective color vision

both aa children and as youths: United States, 1963-70

Type and severity of

red-green defect in

boys 6-11

All types-------------

Protan

Tota.l-----------

MiLd------------------

IWdium ----------------

Strong----------------

D.Q&S?n

Total-----------

Nild------------------

Medium----------------

strong----------------

Type undetermined

Total-----------

Nil.d------------------

Nedium----------------

strong----------------

Total-----------------

Type and severity of red-green defect in boys 12-17

All

redz~~en

Protan Deutan Undetermined

Eects

Total ~fild MediUm Strong Total Mild MediUm Strong Total Mild “:i - Strong

Percent distribution

LOO.O

35.7

13.0

6.2

16.5

52.4

12.1

19.6

20.7

11.9

S.3

3.6

27.7

22.4

2.1

5.0

15.3

3.3

2.1

1,2

2.0

2.0

9.1

=

3.s

2.1

1.7

3.3

2.1

1,2

2.0

2.0

9.9

9.9

3.3

6.6

-

8.7

S.7

8.7

57.1

10.4

8.0

1.2

1.2

39.1

5.3

15.5

18.3

7.6

5.0

2.6

19.7

=

5.5

5.5

7.9

5.3

2.6

6.3

5.0

1.3

21.8

4.9

2.5

1.2

1.2

16.9

10.2

6.7

15.6

-

14.2

-

2.7

11.5

1.3

1.3

15.2

>

2.9

10.0

4.7

2.9

2.4

2.3

1.3

1.0

S.2

J&

1.2

4.7

4.7

2.3

1.3

1.0

5.8

-

~

1.7

4.1

2.9

1.2

1.2

-

1.2

1.2

Number of boys in the population in thouaanda

239 67 22 24 21 135 47 51 37 37 20 14 3

27
APPENDIX I

STATISTICAL NOTES

The Survey Design

The sample design for the first three programs or

Cycles I-HI of the Health Examination Survey has been

essentially similar in that each has been a multistage,

stratified probability sample of clusters of households

in land-based segments. The successive elements for

this sample design are primary sampling units, census

enumeration district, segment (a cluster of households),

eligible persons, and finally the sample person.

The 40 sample areas and the segments utilized in

the design of Cycle 111were the same as those in Cycle

II. Previous reports describe in detail the sample design used for Cycle H and in addition discuss the problems and considerations given to other types of sampling frames, cluster versus random sampling, and

whether or not to control the selection of siblings.6’7

Requirements and limitations placed on the design

for Cycle III, similar to those for children in Cycle II,

were that:

The target population be defined as the civilian

noninstitutional population of the United States,

including Alaska and Hawaii, between the ages of

12 and 17 y~ars for Cycle III, with the special exclusion of children residing on reservation lands

of the American Indians because of operational

problems encountered on these lands in Cycle L

The time period of data collection be limited to

about 3 years for each cycle and the length of the

individual examination within the specially constructed mobile examination center be between 2

and 3 hours.

Ancillary” data be collected on specially designed

household, medical history, and school questionnaires and from birth certificate copies.

Examination objectives be related primarily to

factors of physical and intellectual growth and

development.

The sample be sufficiently large to yield reliable

findings within broad geographic regions and population density groups as well as age, sex, and

limited socioeconomic groups for the total sample.

The sample was drawn jointly with the Bureau of

the Census starting with the 1960 decennial census list

of addresses and the nearly 1,900 primary sampling

units (PSU’S) into which the entire United States was

divided. Each PSU is a standard metropolitan statistical area (SMSA), a county, or a group of two or

three contiguous counties. These PSU’S were grouped

into 40 strata, each stratum having an average size of

about 4.5 million persons, in such a manner as to

maximize the degree of homogeneity within strata with

regard to the population size of the PSU’s, degree of

urbanization, geographic proximity, and degree of industrialization. The 40 strata were then classified into

four broad geographic regions of 10 strata each and

were then, within each region, cross-classified by four

population density classes and classes of rate of population change from 1950 to 1960. Using a modified

Goodman-Kish controlled-selection technique, one PSU

was drawn from each of the 40 strata.

Further stages of sampling within PSU’S required

first the selection of census enumeration districts

(ED’s). The ED’s are small well-defined areas of about

250 housing units into which the entire Nation was divided for the 1960 population census. Each ED was

assigned a “measure of size” equal to the rounded

whole number resulting from a “division by nine” of

the number of children aged 5-9 in the ED at the time

of the 1960 census. A sample of 20 ED’s in the sample

PSU were selected by systematic sampling, each ED

having a probability of selection proportional to the

population of children 5-9 years at the time of the 1960

census date. A further random selection by size of

segments (smaller clusters of housing units) within

each ED was then made.

Because of the 3-year time interval between Cycle

II and Cycle III, the Cycle III frame had to be supplemented for new construction and to compensate for

segments where housing was partially or totally demolished to make room for highway construction or

urban redevelopment.

Advanced planning for the examinations at the

various locations or stands provided for alxsut 17 days

of examinations which limited the number of examinees

per location to approximately 200. When the number of

eligible youths in the sample drawn for a particular

location exceeded this number, subsampling was done

“28
by deleting from the master list of eligible youths

(ordered by segment, household order within segment,

and age within household) every nth name on the list

starting with the yth name, Ybeing a number between

I and ~1selected randomly and n being the extent of oversampling in the original draw.

In Cycle 111, as in Cycle II, twins who were deleted

in the sample selection, were also scheduled for examination, time permitting, as were youths deleted

from the Cycle 111sample who had been examined in

Cycle H. The sample was selected in Cycle HI, as it

had been for the children in Cycle II, so as to contain

the correct proportion of youths from families having

only one eligible youth, two eligible youths, and so on

to be representative of the total target population.

However, since households were one of the elements

in the sample frame, the number of related youths in

the resultant sample is greater than would come from

a design which sampled youths 12-17 years without

regard to household. The resultant estimated mean

measurements or rates should be unbiased but their

sampling variability will be somewhat greater than

those from more costly, time-consuming systematic

sample design in which every kth youth would’ be selected.

The total probability sample for Cycle III included

7,514 youths representative of the approximately 22.7

million noninstitutionalized United States youths of 12-

17 years. The sample contained ”youths from 25 different States and approximately 1,000 in each single year

of age.

The response rate in Cycle III was 90 percent, 6,768

youths being examined out of the total sample. These

examinees were closely representative of those in the

samples as well as the population from which the

samples were drawn with respect to age, sex, race,

region, population density, and ~pulation growth in area

of residence. Hence it appears unlikely that nonresponse

could bias the findings appreciably.

Measures used to control the quality of the data

from these Surveys have been cited previously;7 those

additional measures specifically related to the particular examinations, tests, or measurements are outlined

in the analytic reports describing and presenting the

respective initial findings. As indicated, each of the

seven dentists employed during the youth cycle was

given training and practice in vision testing techniques

throughout his employment to insure the consistency of

test results. As may be seen in table I, the proportion

of youths per thousand found to have red-green color

vision deficiencies showed essentially no differences

that might be attributable to the examiners when age

and sex differences among the examinees at the various locations were removed.

Reliability

While measurement processes in the Surveys were

carefully standardized and closely controlled, the correspondence between the real world and Survey results

cannot be expected to be exact. Survey data are imperfect for three major reasons: (1) results are subTable 1. Examiner variability for red-green d~~;i~iea among youths: Health Examination Survey,

II

Rate and sex

All youths -----------------------

Both sexes

Actual ---------------------------------

Expected -------------------------------

Boya

Actual ---------------------------------

Expected -------------------------------

Girls

Actual ---------------------------------

Expected-------------------;-----------

Examiner

‘Cotal

1 2 3 & 5 6 7

Number of examined youths

5,768 II 11 38 I 476 I 1,817 [ 1,856 I 1,446 I 1,134

Rate per 1,000 with a red-green deficiency

. . .

. . .

. . .

. . .

. . .

. . .

* 27.3

* 27.0

* 47.1

* 45.9

* 4.5

* 3.8

41.3

41.4

73.4

73.6

6.8

6.7

38.3

38.3

71.0

71.1

3.3

3.2 1

51.2 39.7

51.4 39.5

89.3 65.1

88.8 65.6

11.3 7.9

11.8 7.6

29
ject to sampling error, (2) the actual conduct of a survey never agrees perfectly with the design, and (3) the

measurement processes themselves are inexact even

though standardized and controlled.

The first report on Cycle 1117describes in detail

the faithfulness with which the sampling design was

carried out.

Data recorded for each sample youth are Inflated

in the estimation process to characterize the larger

universe of which the sample youth is representative.

The weights used in this inflation process are a product of the reciprocal of the probability of selecting the

youth, an adjustment for nonresponse cases, and a

poststratified ratio adjustment which increases precision by bringing survey results into closer alignment

with known United States population figures by color

and sex within single years of age 12 through 17 for

the youth’s survey.

In the third cycle of the Health Examination Survey

(as for the children in Cycle II) the samples were the

result of three principal stages of selection--the single

PSU from each stratum, the 20 segments from each

sample PSU, and the sample youth from the eIigible

persons. The probabili~ of selecting an individual

youth is the product of the probability of selection at

each stage.

Since the strata are roughly equal in population

size and a nearly equal number of sample youths were

examined in each of the sample PSU’S, the sample design is essentially self-weighting with respect to the

target populatio~ that is, each youth 12 through 17

years of age had aimut the same probability of being

drawn into the respective samples.

The adjustment upward for nonresponse is intended

to minimize the impact of nonresponse on final estimates

by imputing to nonrespondents the characteristics of

“similar” respondents. Here “similar” respondents

were judged to be examined youths in a sample PSU

having the same age (in years) and sex as youths not

examined in that sample PSU.

The poststratified ratio adjustment used in the third

cycle achieved most of the gains in precision which

would have been attained if tie sample had been drawn

from a population stratified by age, color, and sex

and makes the final sample estimates of population

agree exactly with independent controls prepared by the

Bureau of the Census for the United States noninstitutional population as of March 9,1968 (approximate midsurvey point for Cycle III), by color and sex for each

single year of age 12-17. The weights of every responding sample youth in each of the 24 age, color, and

sex classes are adjusted upward or downward so that

the weighted total within the class equals the independent population control for each survey.

Sample frequencies and estimated United States

population frequencies as of the approximate midsurvey point are shown by age, sex, and race in table

II. In addition to youths not examined at all, there were

Table II. Sample of examinees and estimated U.S. population frequency distribution of youths in

the noninstitutional population of the United States, by race, age, and sex: HealEh Examination

Survey, 1966-70

Age and sex

12

13

14

15

16

17

12

13

14

15

;;

Both sexes

12-17 years -------------------

Boys

12-17 years -------------------

years ----------------------------

years ----------------------------

years ----------------------------

years ----------------------------

years ----------------------------

years ----------------------------

Gi.rLi

12-17 years -------------------

years ----------------------------

years ----------------------------

years ----------------------------

years ----------------------------

years ----------------------------

years ----------------------------

~

Number of examinees

6,768

j[

5,735

3,545 3,047

643 540

626 542

618 527

613 525

556 496

489 417

3,223 2,688

547 455

582 490

586 484

503 425

536 441

469 393

999

479

101

80

88

84

57

69

520

88

91

101

73

%

34

19

;

4

3

3

15

I

Total IIWhite Negro Other

races

Population in thousands

T

11,489 9,929

2,032 1,747

2,006 1,729

1,951 1,686

1>900 1,646

1,836 1,594

1,764 1,528

=uJ@-

1,970 1,685

1,946 1,667

1,901 1,633

1,851 1,594

1,789 1,542

1,746 1,502

3,024

1,496

280

262

256

241

231

225

1,527

272

275

266

235

243

237

116

64

1;

1;

11

11

53

14

4

2:

5

7

30
Table III. Extent of missing data for exsminees

on the color vision plate% Health Examination

Survey, 1966-70

Test item

Total number of

parts of color

Vision test

missing ----------

Ishihara plate

--------- --------- -----

:-----------------------

8-----------------------

.---------------------

:;----------------------

~7------,i----”.---------,

H-R-R screening plate

1 ----.--- -------- -------

2-----------------------

.--------.-------------

;-----------------------

5-----------------------

6-----------------------

H-R-R diagnostic plate

-------- ---------------

;-----------------------

9-----------------------

----------------------

::----------------------

--------------.--------

;:----------------------

14----------------------

15----------------------

16----------------------

--------.-------------

:;----------------------

----------------------

;:----------------------

Number of examinees

42

some whose examination was incomplete in one procedure or another. The extent of missing data for the

color vision plates relevant to this report is shown in

table III.

Sampling and Measurement Error

In the present report, reference has been madeto

efforts to minimize bias and variability of measurement techniques.

The probability design oftheSurvey makespossible

the calculation of sampling errors. The sampling error

is used here to determinehowimprecisethesurvey test

results may be because theycomefrom asample rather

than from the measurements of all elements inthe universe.

The estimation of sampling errors fora studyof

the type of the Health Examination Survey is difficult

for at least three reasons: (l) measurement error and ,

“pure” sampling error are confounded inthe data--it

is not easy to find a procedure which will either completely include both or treat one or the other separately, (2) the survey designsnd estimation procedure

are complex and accordingly require computationally

involved. techniques for the calculation of variances,

and (3) from the survey are coming thousandsof statistics, many for suklasses of the population forwhich

there are a amaII number of cases. Estimates”of

sampling error are obtained from the sample data and

are themselves subject to sampling error which may

be large when the number of cases inacell is small

or even occasionally when the number of cases is

substantial.

Estimates of approximate sampling variability

for selected statistics used intbisreport s.re included

in the detsiled tables. l%eseestimates have been prepa~ed by a replication technique which yields overall

variability through observation of variability among

random subasmples of the total sample. Tbe method

reflects both “pure” sampling variance and a part of

the measurement variance.

In accordance with usual practice, the interval

estimate for any statistic may be considered the range

witbin one standard error of the tabulated statistic,

with 68-percent confidence, or the range within two

standard errors of the tabulated statistic, with 95-

percent confidence. The latter is used asthe level of

significance in this report.

An approximation of the standard error of a difference d = x - ~ of two statisticsx and ~ k given by

the formula s’~= (S: +s; )fi where S, and SYare the ssmpling errors, respectively, of and Y. Of course, where

the two groups or measures are positively or negatively

correlated. this will give an overestimate or underestimate, respectively, of the actual standard error.

Small Numbers

In some tables magnitudes are shown 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 statistic has no

meaning in itself except to indicate that the true

quantity is small. Such numbers, if shown, have been

included in the belief that they may help to convey an

impression of the overall story of the table.

0-00

31
APPENDIX II

DEMOGRAPHIC AND SOCIOECONOMIC

Age.—The age recorded for each youth was the

age at last birthday on the date of examination. The age

criterion for inclusion in the sample used in this survey was defined in terms of age at time of interview.

Since the examination usually took place 2 to 4 weeks

after the interview, some of those who were 17 years

old at the time of interview became 18 years old by the

time of examination. There were 23 such cases. In the

adjustment and weighting procedures used to produce

national estimates, these 23 were included in the 17-

year group.

Race. —Race was recorded as “white,” ‘Negro,”

or “other races.” “Other races” included American

Indians, Chinese, Japanese, and all races other than

white or Negro. Mexican persons were included with

TIw~te! ! ~less definitely known to be American Indian

or of another race. Negroes and persons of mixed

Negro and other parentage were recorded as “Negro.”

Geographic Region. -l?or purposes of stratification

the United States was divided into four geographic regions of approximately equal population. These regions,

which correspond closely to those used by the Bureau

of the Census, were as follows:

Region

Northeast -------

Midwest --------

South -----------

Sautes Included

Maine, Vermont, New Hampshire,

Massachusetts, Connecticut, Rhode

Island, New York, New Jersey, and

Pennsylvania

Ohio, Illinois, Indiana, Michigan,

Wisconsin, Minnesota, Iowa, and

Missouri

Delaware, Maryland, District of

Columbia, West Virginia, Virginia,

Kentucky, Tennessee, North Carolina, South Carolina, Georgia,

Florida, Alabama, Mississippi,

Louisiana, and Arkansas

West -----------

TERMS

Washington, Oregon, California,

Nevada, New Mexico, Arizona,

Texas, Oklahoma, Kansas, Nebraska, North Dakota, South Dakota,

Idaho, Utah, Colorado, Montana,

Wyoming, Alaska, and Hawaii

Urban+wal. —The definition of urban-rural areas

was the same as that used in the 1960 census. According

to this definition, the urban population comprised all

persons living in (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 which contained no incorporated

municipalities as subdivisions and had either 2,S00

inhabitants or more, or a population of 2,500 to 25,000

and a density of 1,500 persons or more per square

mile; (4) counties in States other than the New England

States, New Jersey, and Pemsylvania that had no incorporated municipalities within their boundaries and

had a density of 1,500 persons or mdre per square

mile; and (5) unincorporated places of 2,500 inhabitants or more not included in any urban fringe. The

remaining population was classified as rural.

Urban areas are further classified by population

size for places within urbanized areas and other urban

places outside urbanized areas.

Family Income, —The income recorded was the

total income of the past 12 months received by the head

of the household and all other household members related to the head by blood, marriage, or adoption. This

income was the gross cash income (excluding pay in

kind) except in the case of a family with their own farm

or business, in which case no income was recorded.

000

32
APPENDIX Ill

RECORDING SHEET USED FOR COLOR VISION

HEALTH EXAMINATIONSURVEY-III

CO1ORVISION

TESTING

IO RWOR7

Wearz glrwes for test: 10 SOLOR VISION TEST NO. 2–H-R-R (Continued)

Wears contact lenses for test: 2U

Wears neither for test: 3n

PLATE I II

El o

Ill

H

v

Elx

❑ Ncme

❑

x

El o

❑o

❑

v

El x

930

Elv

Iv

❑ Other

I_J Other

❑ Other

❑ Other

❑ Other

l_J Other

❑ Other

❑ Other

❑

TV

COLOR VISION TEST NO. 1- Ishiham binocular test o

PIATE M

❑ other

❑ 3 j_J Other

❑ 2 ❑ Other

I_J Other

❑ Other

❑ 5

❑ 2 QA2

8 1

2

4

8

10

14

17

❑ None

❑

v

%3o

El x

E%v

El

o

%3

v

H

x

m

o

A4i.

R-G

9

10

m

x

o

11

m

o

x

‘2 HVo

❑

,3 Ov

14

m

v

x

El

15 0

x

16

H

o

v

Mod.

SCORE; [If total score for plates 2-17 is 6 skip to page 2 of Vision R-G

Form]

COLOR VISION TEST NUMBER 2–H-R-R

I

❑

ox

EEl

o

v

El

xv

El

Ov

Ill

o

❑x

II

❑ Other

❑ Other

❑ Other

❑ Other

❑ Other

❑ Other

Sev.

R-G

B-Y [

1

2

3

4

5

6

SCORE: (7 through 16) — —

High= ❑ Prot.n ❑ De.t.n

Mod. [17 ~ ❑ ❑ ‘other

‘-y [18❑ ❑ ~ ❑ Other

1’% la H “other

20 ❑ H •!l ‘other

R-G

Sev.

B-Y

SCORE: (17 through 20) — —

SCORE [ 1-6): High = ❑ Tritan ❑ Tetart.n

PHs-4611 -6 [PAGi 1)

REV. 1I-66

SAMPLENO. [1-5]

I

000

33
APPENDIX IV

YOUTHS WITH BOTH RED-GREEN AND

BLUE-YELLOW COLOR VISION DEFICIENCIES

A frequency distribution of youths found to have Five showed mild blue-yellow undetermined deficiencies

specific combinations of both red-green and blue-yellow while two were found in the strong undetermined cotecolor vision deficiencies is shown by sex in table IV. gory. One girl exhibited a mild tetartan defect associ -

Ivlost of the 28 boys affected had a mild blue-yellow ated with a mild red-green undetermined deficiency.

undetermined deficiency in combination with red-green The most frequent combination of deficiencies endefects. The largest frequency of occurrence was in countered among both sexes was a strong red-~ween

combination with a strong red-green deutan deficiency. deutan deficiency associated with a mild blue-yellow

Only eight girls were diagnosed as color deficient undetermined color vision defect.

in both the red-green and blue-yellow perceptual areas.

Table IV. Frequency distribution of youths 12-17 years,

ficiencies,

with both red-green and blue-yellow deby diagnosis and sex: Health Examination Survey, 1966-70

Blue-yellow

deficiency and sex

Both sexes------

Type undetermined:

Mild ---------------

Medium -------------

Strong -------------

Tetartan:

Medium -------------

Strong -------------

Boys ------------

Type undetermined:

Mild---------------

Medium -------------

Strong -------------

Tetartan:

Medium -------------

Strong -------------

Girls ----------

Type undetermined:

Mild ---------------

Medium-------------

Strong -------------

Tetartan:

Medium -------------

Strong -------------

Total

36

31

2

2

1

28

26

i

8

5

‘i

1

Protan

Iild Medium Strong

1 3 5

1 3 5

1 3 5

1 3 5

Red-green deficiency

Deutan

T

Mild Medium

T

1 4

1 4

&

1 2

1 2

;m ong

11

11

11

11

(ild

7

4

i

1

4

3

i

3

1

i

1

Undetermined

Medium

4

2

2

2

1

i

2

1

i

Strong

*U. S. GOVERNMENT PSINTING OFFICE :1974 543-S81/45

34
Series 1.

Series 2.

Series 3.

Sm”es 4.

Sm”es 10.

Sw”es 11.

Sm”es 12.

S--es 13.

Series 14.

Sm”es 20.

Sm”es 21.

Sm”es 22.

+

VITAL AND HEALTH STATISTICS PUBLICATION SERIES

Originally Public Health Service bblication No. 1000

Programs and collection procedures. —Reports which describe the general programs of the Nattonal

Center for Health Statistics and its offices anddivisiona, data collection methods used, definitions,

and other material necessary for understanding the data.

lkata evaluation and methods research. —Studies of new statistical methodology including: experi- ‘

mental tests of new survey methods, studies of vital statistics collection methods, new analytical

techniques, objective evaluations of reliability of collected data, contributions to statistical theory.

Analytical studies .-Repcwts presenting analytical or tttterpretive studies basedon vttal and health

statistics, carrying the analysis further than the expository types of reports in the other series.

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

Mrth and death certificates.

LMta from the Health Interm”ew Swrvev. —Statistics on illness, accidental injuries, disability, use

of hospital, medical, dental, and other services, and other health-related topics, baaed on data

collected in a continuing national household interview survey.

Data from the Health Examination Survey. —Data from direct exatntnatton, testing, and measurement of national samples of the civilian, noninstitutional population provide the basis for two types

of reports: (1) estimates of the medically deftned 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.

DOta from the Institutional Population Surveys —Statistics relating to the health characteristics of

persons in institutions, and their medical, nursing, and personal care received, based on national

samples of establishments providing these services and samples of the residents or patients.

Data from the Hospital Discharge Survey. —Statistics relating to discharged patients in short-stay

hospitals, based on a sample of patient records in a national sample of hospitals.

mta 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.

Data on mortality. —Various statistics on mortality other than as included in regular annual or

montiy reports-special analyses by cause of death, age, and other demographic varfables, also

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LWa on natality, marriage, and divorce. —Various statistics on nataltty, marriage,, and divorce

other than as included in regular annual or monthly reports-special analyses by demographic

variables, also geographic and time series analyses, stuclies of fertility.

DOtU from the Natwnal Natality and Mortality Surveys. — Statistics on characterisdcs of births

and deaths not available from the vital records, based on sample surveys stemming from these

records, including such topics as mortali~ by socioeconomic class, hospital experience in the

last year of life, medtcal care during pregnancy, health insurance coverage, etc.

/

F6r’!a list of titles of reports published in these series, write to: Office of Information

National Center for Health Stat istics

Public Health Service, HRA

Rockville, Md. 20852