DISCUSSION

Aphakia has become increasingly prevalent in the civil airman population. While the
total civil airman populaticn decreased by approximately 4.43% from 1982 to 1985, the
frequency and prevalence of aphakic airmen increased substantially during the same period.
The percentage increase in the prevalence of aphakia by type, class of medical certificate,
and gender was higher for bilateral, second-class certificate holders, and males, respectively.
The ratio of frequency of aphakia in the older airman population (=50 years of age) was on
an average 9 times higher for unilateral and 26 times higher for bilateral conditions than in
the younger airman population (<50 years of age). Although a higher ratio of frequency of
aphakia in older airmen was anticipated (since cataract is often an age associated vision
condition and a lens extraction procedure would be necessary in order to pass the medical
certification vision standards), a ratio of this magnitude was greater than we have observed in
our clinical experiences.

The decline in boih the number of new cases of aphakia and the incidence per 1,000
airmen, which appears to be contrary to the increasing trend in cataract surgery in the United
States during the study period, may suggest important implications to flight safety and to the
airman medical certification process. Factors that could contribute to these unexpected
findings include:

1) Self-selection (voluntary removal) from flight status by airmcn with cataract
and aphakia due to perceived or real visual impairment while in the cockpit;

2) Reluctance of airmen with cataract to have their pathology corrected with
surgery;

3) Tacompatibility of modes of correction (intraocular lens implant, contact
lenses) or complications of surgical procedures for aphakia to certain flight
operations or environments;

4) Vision disability (e.g., glare, reduced accommodation, field of vision) as a
result of aphakia during routine aviation procedures being considered
hazardous; and

5) More stringent FAA disqualification criteria being initiated during the study
period.

Improvements in the surgical procedures, instrumentation, and aphakic therapeutic
modalities have aided airmen with cataracts to correct their condition and improve their
vision to meet current FAA medical standards. Although in recent years these improvements
have reduced the incidence of complications from cataract surgery with intraocular lens
impiantation (8), there are concerns expressed by some medical experts related to these
procedures which may directly affect the aviator. These concerns include: greater glare


THE PREVALENCE OF APHAKIA IN
THE CIVIL AIRMAN POPULATION

INTRODUCTION

An association of age-related visual conditions with aircraft accidents has been identified
in prior studies. Harper (1), in a study of 3,182 pilots in general aviation accidents during
1963, found that visual defects were 2.1 times more frequent in a sample population of
airmen invoived in accidents than in the total pilot population, and that older pilots comprised
a significant proportion in the accident related sample. Dougherty & Harper (2) reported
that the average pilot medically certified in 1963 with eye pathology had a relative accident
risk 1.78 times greater than that of pilots with ne defects. Dille & Booze (3), in the 1979
study of accidents involving airmen with vision pathologies, found that aphakia and artificial
lens implant populations had significantly higher accident rates when compared to the total
airman population. In a follow-up study of 1980-81 airman accidents, Dilie and Booze (4)
found that pilots with aphakia and artificial lens implant, when compared to the total airman
population, had higher rates in two categories of exposure: accident rates per 1,000 airmen
per year and accident rates per 100,000 hours of recent flight time.

Elderly pilots are becoming a larger percentage of the total civi! airman population. In
1966, pilots over 50 years of age made up only 9.5% of the total civil airman population.
Twenty years later, that age group increased to almost 22% of the total population (5). As
the frequency of elderly pilots increases, the prevalence oi visual impairment also increases.
Eye pathology, the most prevalent medical condition among active airmen (48.9/1,000
population) as of January 1, 1980 (6), increased in prevalence rate to 63.8/1,000 population
by 1986-87 (7).

Cataract, a ccadition in which a loss of transparency of the crystalline lens or its capsule
has occurred, is the third leading cause of blindness in the United States (8) and is normally
associated with the aged. Aphakia, a condition in which the crystalline lens of the eye has
been extracted, is usually a result of a cataract. In 1980, approximately 396,000 cataract
procedures were performed in the United States (9); while in 1988, nearly one million
cataract operations were performed (8). Cataract surgery accounts for about 46% of all eye
operations in the United States (10) and currently results in a success rate of better than 98%
(11). There are three ophthalmic devices normally employed to correct aphakia: spectacles,
contact lenses, and artificial or intraocular lens (OL) implants.

-


FREQUENCY OF APHAKIC
AIRMEN BY CLASS AND YEAR

2000;

FREQUENCY

———_+___.+—__——
°. . ‘

PREVALENCE OF APHAKIC
AIRMEN PER 1000 AIRMEN
BY CLASS AND YEAR

&

PREVALENCE

°

1982 1983 1984 1988

1982 1983 1984 1985
CLASS! >; 110 113 | 122 141 [euass: | 1086 4168 119 1281
Joussi +} azo 454 458 as | 1 CLASS *! 1495 | 1874 | 1946 220
CLASS Hw! 1299 f 1405 | 1877 ie LCIASS ih 1 3439 3748 4yut 43%
YEAR YEAR
Figure 4 Figure 5

The frequency of aphakic airmen by
class of medical certificate (first, second
and third-class) and by year during the
study period is presented in Figure 4.
First-class increased by 28.18%, second-
class by 31.13%, and third-class by
24.02% between 1982 and 1985.

The prevalence of aphakic airmen by
class of medical certificate and by year
during the study period is presented in
Figure 5. The percentage increase in the
prevalence of active second-class aphakic
airmen (53.16%) is higher than either
first-class (18.85%) or third-class
(25.33%) between 1982 and 1985.



METHODS

The study protocol included:

1.

A listing was generated identifying in FAA computer files all civil airmen who were
issued airman medical certificates between January 1, 1980, and December 31, 1985,
who carried one or both of the FAA-specific pathology codes 134 (aphakia) and 160
(artificial lens implant).

The medical records of these airmen were reviewed and selected information
extracted from each record and recorded on individual data cards.

A Vision Defect Database was constructed from the medical examination records and
FAA computer files; it contained demographic (name, date of birth, sex, restrictions,
etc.) and medical (date and type of cataract extraction, date and type of artificial lens
implanted, type of corrective modality, etc.) data on these aphakic airmen, if known.

The frequency of active airmen (those holding a current medical certificate) with
aphakia was determined as of December 31 of each year of the study period (Note:
Aeromedical certification guidelines consider an airman to be active for a period of 24
months after the month in which the certificate 1s issued.).

The aphakic airmen were stratified by type (unilateral, bilateral) of aphakia, effective
class of medical certificate held, gender, and age.

Point prevalence and incidence were calculated using the total active airman
populations from the Aeromedical Certification Statistical Handbook (16).


Aphakic spectacles have many disadvantages, including: reduced peripheral field of
vision; enlarged visual image (30% magnification); aniseikonia in monocular aphakia; and
prismatic and aberrational effects that require head rather than eye movements (12). Flying
when wearing one or more "cataract" spectacle lenses is generally considered unacceptable
because of the extreme degree of anisometropia present and the seriously affected field of
vision (13). Although superior to spectacles, contact lenses to correct for aphakia have their
own deficiencies. Compliance is poor, especially with rigid lenses (£4); they are more
difficult to locate when misplaced and are poorly handied by older aphakics; and their
wearers are more prone to infections and more often develop sensitivities to contact lens
solutions.

The first modern-day artificial lens implant was performed by Dr. Harold Ridley in
1949, However, during the next 10-20 years, because of problems in surgical procedures,
lens designs, and sterilization techniques, the use of implanted lenses was performed by a
handful of ophthalmic surgeons primarily in fereign countries. Only in the last decade has
artificial lens implantation become the primary therapeutic modality for correcting aphakia.
In the United States, the percentage of cataract surgeries that include intraocular lens
implantations has risen from 30% in 1980 (9), to 90% in 1988 (8). Advantages of
intraocular lenses include: freedom from patient handling, normal peripheral vision, minimal
aniseikonia, and rapid return of binocular vision (10).

Airmen must meet specific Federal Aviation Administration (FAA) medical standards to
obtain a particular class of medical certificate. There are three classes of airman medical
certificates: first-class {airline transport pilot), second-class (commercial pilot), and third-
class {private pilot) (15). The designated Aviation Medical Examiner may issue a medical
certificate to an aphakic applicant for a third-class medical certificate, if the applicant meets
certain medical standards. Applicants for first- and secund-class airman medical certificates
who have had cataract surgery are deferred issuance of a certificate and their applications are
submitted to the FAA Aeromedicai Certification Division for further consideration. A
waiver can be granted for such applicants (15), after review of a completed ophthalmological
evaluation.

Prompted by the substantial frequency of visual defects and the associated corrective
procedures and devices used in the airman popviation, the Federal Air Surgeon requested a
continuing research effort on vision disorders as they affect airman performance. The Vision
Research Section, Civil Aeromedical institute, in collaboration with the Aeromedical
Certification Division, performed an epidemiclogic study on two certifiable eye pathologies
(aphakia and artificial leas implant) and their association io aviation accident risk in civilian
airmen during the study period (1982-85). Due to the size of the database, the report on
airmen with artificial lens implants and the association of aphakia to aviation accident risk
will be presented in separate publications. The objective of this paper is to present the
results of a descriptive analysis of aphakia in the civil airman population during the study
period.


FREQUENCY OF APHAKIC
AIRMEN BY TYPE AND YEAR

2500

z000l-- - a |

WoOhs eee eee

FREQUENCY

PREVALENCE

4O00b- eee eee eee

° 4 ;
196219831988 1985

PREVALENCE OF APHAKIC
AIRMEN PER 1000 AIRMEN
BY TYPE AND YEAR

3.5;

i
in

x

2.8!

iw

jo . 4 A
1982 1983 1984 1085

UNILATERAL *| 1135, 1258 1382 4362 UNILATERAL #7] asap [3.757 J 3.876 | 3.986
BILATERAL +} 653 m4 803 as7 BUATERAL +| o8or | 0997 | 1.116 | 1.267
TOTAL | 1768 | 1972 | 2155 | 2249 {TOTAL | 2461 | 2755 | 2901 | 3273
YEAR YEAR
Figure 2 Figure 3

The frequency of aphakic airmen by
type (unilateral, bilateral) and by year
during the study period is presented in
Figure 2. Total active aphakic airmen
increased by 25.78%, unilateral aphakics
by 20.00%, and bilateral aphakics by
35.83% between 1982 and 1985.

The prevalence of aphakic airmen by
type and by year during the study period is
presented in Figure 3. The prevalence of
toial aphakic airmen increased by 31.62%,
while the percentage increase in the

revalence of unilateral (25.57%) aphakic
airmen is lower than that of bilateral
(42.13%) aphakic airmen between 1982
and 1985.


D-A241 032
a

DOT/FAA/AM-91/14

Office of Aviation Medicine
‘Washington, D.C. 20591

91-12182
Cea

YQ)
The Prevalence of \“~
Aphakia in the Civil
Airman Population

Van B. Nakagawara
Faredoon K. Loochan

Kathryn J. Wood

Civil Aeromedical Institute
Federal Aviation Administration
Oklahoma City, OK 73125

August 1991

Final Report

This document is available to the public through
the National Technical Information Service,
Springfield, Virginia 22161.

2

U.S. Department
of Transportation

Federal Aviation
Administration


PREVALENCE OF APHAKIC AIRMEN
PER 1000 AIRMEN BY GENDER AND YEAR

4

PREVALENCE
8.
T

1982 1983 1984 1285

NUMBER OF NEW CASES
OF APHAKIC AIRMEN
BY TYPE AND YEAR

350,

p
a
2

FREQUENCY
e 8
$8

: 1

3
8
7—F-

1962 1983 1984 1985

UNILATERAL ~[ 196 | 214 [| 202 138
FEMALE *] 0 886 L oats [ o9se fT o9t BILATERAL +1 6 8 408 45
MALE +] 2543 2.874 3.124 3.363 YOTAL | 262 312 310 223
YEAR YEAR
Figure 7 Figure 8

The prevalence of total aphakic
airmen by gender and by year is presented
in Figure 7. The percentage increase in
the prevalence of active female aphakics
(2.78%) is lower than for their male
(32.23%) counterparts between 1982 and
1985.

The number of new cases of aphakic
airmea by type and by year during the
study period is presented in Figure 8.
Compared to its peak value in 1983, there
is a decline in new cases of both the
unilateral (-35.51%) and the total
(-18.91%) aphakic populations in the last 2
years of the study, while new cases of
bilateral aphakia have increased by
33.72% between 1982 and 1985.

a


FREQUENCY

FREQUENCY OF FEMALE
APHAKIC AIRMEN BY YEAR

The frequency of aphakic
airmen by gender (female, male)
and by year during the study
feriod is presented in Figure 6.
Female apnakics decreased by
2.50%, while male aphakics
increased by 26.43% between
1982 and 1985.

sane

SS 40 T. 45 i 43 I 39

YEAR
FREQUENCY OF MALE
APHAKIC AIRMEN BY YEAR

2500

2ocon: - -
i
H pisces -
4 =
) § |
| Bison eee . {
goons ee -
|
| t : A
{ 1a82 1983 1984 1985
H 748 7932 Bie 2270
YEAR
Figure 6


RESULTS

Among the airmen who were issued airman medical certificates between January 1,
1980, and December 31, 1985, 3,499 airmen were identified with pathology codes 134
and/or 160. Upon review of the medical records, it was discovered that 156 airmen were
inappropriately coded and 10 medical records were unsalvageable, resulting in a total aphakic
airman popuiation of 3,333.

The trend in the total active civil airman population during the study period by year is
presented in Figure 1. The total airman population ha: :..clined over the years, decreasing
by 4.43% since 1982.

TOTAL ACTIVE CIVIL
AIRMAN POPULATION
Boo0oe 7S2515 _718858 720824 uae
700000 +"
600000 + a
So0000+ a
400000 40
300000 +"
200000 4" |
100000 +
oo > = +
1982 1983 1884 19385
YEAR

Figure 1


ACKNOWLEDGMENTS

The authors gratefully acknowledge the assistance provided by Lela M.
Brown, M.S., and Najmul H. Chowdhury, M.B.B.S., M.P.H, who provided
statistical and computer support; the late Charles F. Booze, Jr., Ph.D., and Leslie
Downey, staff members of the Statistics and Records Branch, Aeromedical
Certification Division, who provided consultation and technical support; and Jerry
R. Hordinsky, M.D., Manager of the Aeromedical Research Division, who
critically reviewed our protocol.



sensitivity (17), incidence of other pathologies {retinal detachme-t, cystoid macular edema,
glaucoma) (18), and injury to intraocular structures (19). Although not reported in this
manuscript due to the variable information in the airman medical records, all major cataract
etiologies (age-related, congenital, traumatic, etc.) and types of cataract extraction procedures
(intracapsular, extracapsular and Kelman phacoemulsification) were present in the aphakic
airman population. Surprisingty, it was not unusual to find an airman with different types of
extraction procedures between two eyes. These various surgical procedures are being
considered in future research protocols for further evaluation as to their impact on vision
performance in flight simulations.

CONCLUSIONS

This study shows an increased prevalence of cataract extraction surgery in the airman
population. The continued modification of these procedures, coupled with possible visual
complications in flight operational settings, strongly suggest that continued aeromedical
attention is needed to assess the current acceptability of aphakia and corrective devices for
aphakia in the airman population. To aid in future FAA epidemiologic studies, the Aviation
Medical Examiner should assure that complete information on each aphakic airman is
properly documented on their medical records (FAA 8500-8 - Application for Airman
Medical Certificate or Airman Medical and Student Pilot Certificate; FAA 8500-7 - Report
of Eye Evaluation (15)), including: date of surgery, _ype of correction, complications, etc.
Additionally, a study of aphakic airmen who have discontinued flying to determine the effect
of aphakia on their decision would be valuable in evaluating individual cases for waivers.

il


11.

12.

13.

14,

15.

16.

17.

18.

19.

Frank A, Werfel N. ECCE with phacoemulsification. J Ophthalmic Nurs Technol.
i988; 7:62-7.

Roper-Hall MJ. Intraocular lenses. In: Duane TD, ed. Clinical Cphthalmology.
Vol. 5. Hagerstown:Harper & Row, 1979:1-5.

Dhenin G. Ophthalmological conditions and eye examination. In: Aviation Medicine:
Health and Clinical Aspects. London:Tri-Med Books Limited, 1978:264-302.

Boyd BF. Highlights of Ophthalmology. 1974-1975 Series; 3:1-6.

Department of Transportation/Federal Aviation Administration, Guide for aviation
medical examiners. Washington, DC:1981; FAA Office of Aviation Medicine.

Department of Transportation/Federal Aviation Administration. Aeromedical
certification statistical handbook. Washington DC:1982-1985; FAA Civil Aeromedical
Institute, Aeromedical Certification Division; Report No. AC 8500-1.

Nadler DJ, Jaffe NS, Clayman HM, Jaffe MS, Luscombe SM. Glare disability in
eyes with intraocular lenses. Am J Ophthalmol. 1984; 97:43-7.

Amott EJ. Intraocular implants. Trans Ophthalmol Soc UK. 1981; 101:58-60.

Miller D, White P. Intraocular lenses and cataracts: a clinical guide for
optometrists. Contemp Optom. 1983; 2:25-35.

13

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Technical Report Documentation Page

1. Report No. | 2. Government Accession No. 3. Recipient s Cataiag No.
DOT/FAA/AM-S1/14
4. Tithe ond Subtitle 5. Report Date —
i August 1991
| THE PREVALENCE OF APHAKIA IN THE CIVIL AIRMAN ©. Performing Organization Code
_ POPULATION

[8. Performing Organization Report No

7 Author's’ Van B, Nakagawara, O.D.; Faredoon K. Loochan, B.S.;
Kathryn J. Wood

9. Performing Organizetion Name and Address 10. Work Unit No. (TRAIS)
FAA Civil Aeromedical Institute
P.O, Box 25082 ii” Contract or Grant No.

Oklahoma City, Oklahoma 73125

13. Type of Report and Period Covered

12. Sponsoring Agency Name ond Address
Office of Aviation Medicine
Federal Aviation Administration
800 Independence Avenue, S.W. 14. Sponsoring Agency Code
Washington, D.C. 20591

- Supplementary Notes

This work was performed under task AM-A-91-PHY-144

16. Abstrect

The Federal Aviation Administration allows civilian airmen with aphakia to fly with waivered
certificates. This study analyzes the distribution of aphakia in the civil airman population by type
;  @nilateral, dilateral), class of airman medical certificate, and gender for a 4-year period (1982-85).
| Medical records were evaluated for all certifed airmen during the study period who were carrying
pathology codes for aphakia and artificial lens implant. The percentage increase in the prevalence
of aphakia was higher for bilateral, second-class certificate holders, and male aphakics. The
incidence of total and unilateral aphakia declined during the last 2 years of the study period. Aphakia
has become increasingly prevalent in the civil airman population. The increased application and
modification of surgical procedures for cataract extraction, coupled with possible visual complications
from these procedures in flight operations, strongly suggests continued specialized aeromedical
certification and clinical research review.

TA Key Words 18. Distribution Statement

| Vision; Epidemiology; Aphakia; Lens, Document is available to the public

| Intraocular; Medical Certification through the National Technical Information

| Service, Springfield, Virginia 22161

49, Security Classif. fo! { 26. Security Classif, (of this page) i 2i- No. of Poges {| 22. Price
| Unclassified | Unclassified 17 |

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized


NOTICE

This document is disseminated under the sponsorship of
the U.S. Department of Transporzation in the interest of
information exchange. The United States Government
assumes no liability for the contents or use thereof.


INCIDENCE OF APHAKIC
AIRMEN PER 4000
| AIRMEN BY TYPE AND YEAR

°

The incidence of aphakic airmen per
1,000 airmen by type and by year during the
study period is presented in Figure 9. As in
whe number of new cases of aphakic airmen,
Since 1983 there is a decline in incidence of

°

iV)

both the unilateral (-34.00%) and the total
S| (-16.93%) aphakic populations in the last 2
Zo2t years of the study, while the incidence of
ee \ | bilaterei aphakia has increased by 38.97%
! between 1982 and 1985.
|
|

1983 1984 1985,
03 o2ss | 9.198
0.187 0.15 { 0.186
0.437 | 0.432 _| 9.353

Using the Chi-Square test (Xc}, the number of older aphakics (age category =50 years
of age) was found io be significantly greater (p <.001) when compared to the number of
younger aphakics (<50 years of age) in the airman population for each year of the study.
The average ratio of frequency for the study period of unilateral aphakia was 9.20 + .202,
and that of bilateral aphakia was 26.69 + 1.57 in airmen =50 years of age relative to
airmen <50 years of age.


10.

REFERENCES

Harper CR. Physical defects of civilian pilots related to aircraft accidents.
Aerospace Med. 1964; 35:851-6.

Dougherty JD, Harper CR. Physical defects of civilian pilots related to aircraft
accidents: a new look at an old problem. Aerospace Med. 1968; 39:521-7.

Dille JR, Booze CF Jr. The prevalence of visual deficiencies among 1979 general
aviation accident airmen. Washington, DC: Department of Transportation/Federal
Aviation Administration;1981; FAA Report No. AM-81-14. Available from: National
Technical Information Service, Springfield, VA 22161. Order #ADA106489/8.

Dille JR, Booze CF Jr. The 1980 and 1981 accident experience of civil airmen with
selected visual pathology. Washington, DC: Department of Transportation/Federal
Aviation Administration; 1983; FAA Report No. AM-83-18. Available from: National
Technical Information Service, Springfield, VA 22161. Order #ADA134898.

Nakagawara VB. The relevance of vision defects in the medical certification of
civilian airman. In: Goss DA, Edmondson LL, eds. Proceedings of the 1988
Northeastern State University Symposium on Theoretical and Clinical Optometry.
March 25, 1988. Tahlequah, OK. 1988:59-71.

Booze CF Jr. Prevalence of selected pathology among currently certified active
airmen. Washington, DC: Department of Transportation/Federal Aviation
Administration;1981; FAA Report No. AM-81-9. Available from: National Technical
Information Service, Springfield, VA 22161. Order #ADA103397/6.

Booze CF Jr. Prevalence of disease among active civil airmen. Washington, DC:
Department of Transportation/Federal Aviation Administration; 1989; FAA Report
No. AM-89-2. Available from: National Technical Information Service, Springfield,
VA 22161. Order #ADA206050.

Goodman DF, Stark WJ, Gottsch JD. Complications of cataract extraction with
intraocular lens implantation. Ophthalmic Surg. 1989; 20:132-40.

Boyd BF. Highlights of Ophthalmology. 1980 Series; 8:1-3.

Alexander LJ. Aphakia and pseudophakia. In: Amos JF, ed. Diagnosis and
Management in Vision Care. Boston:Butterworth, 1987:639-69.

12