BLINDNESS FROM GLAUCOMA RITA HILLER, M.S.,

AND HAROLD A. K A H N ,

M.A.

Bethesda, Maryland emphasize internal comparisons among vari­ ous subgroups rather than the absolute level of registration. Recent register incidence and prevalence rates per 100,000 population by sex and race are limited to 14 states because detailed data in the required format were not available from Massachusetts or New York (Tables 1-5). Both crude and age-standardized rates are shown. The crude rates are simply the total number of cases ( X 100,000) divided by the corresponding total population. Age-stan­ dardized rates* were computed according to the direct method9 with the age distribution of the total 1970 census population of the 14 states as standard, and are used to adjust for different proportions of younger and older persons among the various groups. Population data for 1969 and 1970 are the July 1 estimates for the resident state pop­ ulation10 with the age-color-sex details ap­ portioned as in the 1970 census for the cor­ responding state. MRA data for 1963 to 1968 were taken or derived from the pub­ lished MRA monographs for those years.11"18

Present day medicine and surgery are be­ lieved capable of preventing blindness from glaucoma, provided it is recognized and treated early.1 It is therefore distressing to find that glaucoma continues to be one of the leading causes of blindness in the United States today, especially among nonwhites.2 In this study we had the following objec­ tives: (1) to present, in some detail, recent data derived from the U.S. Model Reporting Area for Blindness Statistics ( M R A ) ; (2) to assess trends in blindness due to glaucoma by comparing recent MRA data with earlier years; and (3) to compare MRA findings with other available data on blindness from glaucoma with respect to risk factors and trends. Description of the MRA—Our source of the new data is the MRA for Blindness Sta­ tistics for which detailed descriptions are available elsewhere.3'4 For convenience, the MRA consists of a group of state blindness registries that maintain statistics according to a common definition of blindness—visual acuity of 20/200 or less in the better eye with best correction or visual field limited to 20 degrees in its widest diameter5—and follow common rules for coding and updating rec­ ords. The MRA began in 1962 with nine states and the number gradually increased to 16 states by 1970, the most recent year for which MRA data are available.

Unless otherwise specified, the specific cause data in all tables in this paper are restricted to single causes of blindness and are derived from the diagnostic reports on persons registered as blind with the appro­ priate state agency. Glaucoma in the MRA includes primary glaucoma, both chronic sim­ ple and narrow angle, and glaucoma not specified as either primary or secondary. We excluded glaucoma specifically reported as

It is generally assumed that the MRA data understate new cases of blindness. The de­ gree of understatement is not known, but rough indications6"8 suggest that the true incidence of blindness may be as much as twice the register incidence. However, we

1

The age-standardized rate is computed as ZNuPiu P'u = ZNi, where Piu= rate/100,000 in age group i of population u N ia = number in age group i of standard population 2 is a symbol for addition, in this case addition over all age groups.

From the Office of Biometry and Epidemiology, National Eye Institute, Department of Health, Edu­ cation and Welfare, National Institutes of Health. Reprint requests to R. Hiller, Office of Biometry and Epidemiology, National Eye Institute, National Institutes of Health, Bldg. 31, Rm. 6A-18, Bethesda, MD 20014. 62

VOL. 80, NO. 1

63

BLINDNESS FROM GLAUCOMA

secondary or congenital from the glaucoma category in this paper. Of the known pri­ mary cases in the 1969-1970 MRA, chronic simple glaucoma accounts for 89%. RESULTS

MRA by cause, sex, race, and age— 1969 to 1970—Additions to blindness regis­ ters from 1969 to 1970 and persons on the registers as of Dec. 31, 1970, for 14 MRA states were compiled by cause and sex (Table 1) and by cause and race (Table 2 ) . Glaucoma was a leading cause of blind­ ness in the U.S. (Tables 1 and 2). The agestandardized rates showed that glaucoma ranks as the third leading cause of blindness. The rates of blindness from glaucoma were

slightly higher for men than for women, true for both register incidence and register prev­ alence (Table 1). While blindness from glau­ coma still ranked high among whites, it was the major cause of blindness for nonwhites (Table 2). (The composition of known nonwhites in the 1970 14-state MRA population was 97.5% black, 1.7% native American, and 0.8% other.) The ratio of nonwhites to whites in the age-standardized rates of glau­ coma for additions to register and total on register was 8.3 and 8.4 respectively, as com­ pared to 2.0 and 2.2 for all other causes. If we calculated age-standardized rates for glau­ coma with or without other associated causes of blindness and included a proportional allo­ cation of unknown causes, then the ratio of

TABLE 1 AVERAGE ANNUAL ADDITIONS TO BLINDNESS REGISTERS 1969-1970 AND PERSONS ON THE REGISTERS DEC. 3 1 , 1970, BY CAUSE AND SEX (14 MRA STATES)

Average Annual Additions, 1969-1970 Cause

Total

Men

Women Men/Women Ratio

Persons on Register Dec. 31, 1970 Total

Men

Women Men/Women Ratio

Number Glaucoma 544 Cataract 778 Diabetic retinopathy 464 Retinal (other than di­ abetic retinopathy) 1,121 Optic nerve 352 Uveitis 154 Cornea or sclera 136 Myopia 118 All causes* except glaucoma 4,784

276 321 172

268 457 292

— —

6,059 7,202 2,575

2,909 3,235 947

3,150 3,967 1,628

508 213 72 65 62

613 139 82 71 56

— — — — —

11,142 5,042 2,822 2,584 1,627

5,428 2,997 1,394 1,204 849

5,714 2,045 1,428 1,380 778

2,161

2,623



48,824 23,991

24,833

Age-Standardized Rate/100,000 Glaucoma Cataract Diabetic retinopathy Retinal (other than di­ abetic retinopathy) Optic nerve Uveitis Cornea or sclera Myopia All causes* except glaucoma

1.46 2.07 1.23

1.68 1.89 0.94

1.27 2.17 1.46

1.3 0.9 0.6

16.2 19.2 6.9

18.2 19.5 5.5

14.6 18.7 7.9

1.2 1.0 0.7

2.98 0.96 0.40 0.36 0.31

3.06 1.17 0.42 0.37 0.34

2.90 0.69 0.42 0.35 0.28

1.1 1.7 1.0 1.1 1.2

29.7 13.5 7.5 6.9 4.3

32.5 17.2 8.1 7.1 4.8

27.0 10.3 7.1 6.7 3.9

1.2 1.7 1.1 1.1 1.2

12.78

12.68

12.70

1.0

130.3

140.7

120.2

1.2

* Includes retrolental fibroplasia, multiple affections, other and unknown causes.

AMERICAN JOURNAL OF OPHTHALMOLOGY

64

JULY, 1975

TABLE 2 AVERAGE ANNUAL ADDITIONS TO BLINDNESS REGISTERS 1969-1970 AND PERSONS ON THE REGISTERS DEC. 3 1 , 1970, BY CAUSE AND RACE ( 1 4 M R A STATES)

Average Annual Additions, 1969-1970 Cause

Total

ww»

Non

white

Nonwhite/ White Ratio

Persons on Register Dec . 31, 1970 Total

White

Nonwhite

Nonwhite/ White Ratio

Number Glaucoma 544 Cataract 778 Diabetic retinopathy 464 Retinal (other than di­ abetic retinopathy) 1,121 Optic nerve 352 Uveitis 154 Cornea or sclera 136 Myopia 118 All causes* except glaucoma 4,784

250 582 349

294 196 115

— — —

6,059 7,202 2,575

2,832 5,253 1,951

3,227 1,949 624

— — —

983 248 105 79 82

138 104 49 57 36

— — — — —

11,142 5,042 2,822 2,584 1,627

9,466 3,257 1,853 1,578 1,216

1,676 1,785 969 1,006 411

— — — — —

3,692

1,092



48,824 36,712

12,112



Age-Standardized Rate/100,000 Glaucoma Cataract Diabetic retinopathy Retinal (other than di­ abetic retinopathy) Optic nerve Uveitis Cornea or sclera Myopia All causes* except glaucoma

1.46 2.07 1.23

0.78 1.80 1.05

6.51 4.13 2.50

8.3 2.3 2.4

16.2 19.2 6.9

8.6 16.1 5.9

72.0 40.7 13.6

8.4 2.5 2.3

2.98 0.96 0.40 0.36 0.31

2.99 0.79 0.32 0.24 0.27

2.82 2.03 0.99 1.16 0.62

0.9 2.6 3.1 4.8 2.3

29.7 13.5 7.5 6.9 4.3

28.9 10.1 5.7 4.8 3.8

35.0 37.5 20.4 21.3 7.9

1.2 3.7 3.6 4.4 2.1

12.78

11.39

22.24

2.0

130.3

112.9

250.3

2.2

* Includes retrolental fibroplasia, multiple affections, other and unknown causes.

nonwhite to white was 7.4 for additions to register and 7.1 for total on 1970 register. To learn if this seven- to eightfold ratio for nonwhites compared to whites applied to individual states, we computed age-standard­ ized rates by race for each of the 14 MRA states. When the number of nonwhites on the register for glaucoma blindness was over 15 persons, no state had a ratio of less than 7:1 (Table 3). We observed the large differential between nonwhite and white rates for both men and women (Table 4). Men and women of both races experienced rapid increase in fre­ quency of blindness with age. Age-specific rates of blindness from glaucoma in nonwhites were higher than in whites for every

age group, with the greatest difference noted at 45 to 64 years, where the ratio of nonwhite to white rates was almost 15:1. The ratio of nonwhite 1970 addition rates to those for whites showed the nonwhite at higher risk for blindness at every blindness level from 20/200 to absolute blindness (Table 5). Trend in MRA datcn-1963 to 1970—We compiled the available data on trend of glau­ coma blindness during 1963 to 1970 (Table 6). The rates came from the cases added to registers and the state populations in the Statistics on Blindness Series.2'11"16 To min­ imize bias, the blindness rates from glaucoma were calculated each year, beginning with 1963, on a constant group of states. The rate of register incidence for blindness from glau-

VOL. 80, NO. 1

65

BLINDNESS FROM GLAUCOMA TABLE 3

NUMBER AND AGE-STANDARDIZED RATE/100,000 OF PERSONS ON REGISTERS DEC. 31,1970, BECAUSE OF GLAUCOMA BY STATE AND RACE (14 MRA STATES)

White

All states Connecticut Georgia Kansas Louisiana New Hampshire New Jersey New Mexico North Carolina Oregon Rhode Island South Dakota Utah Vermont Virginia

Nonwhite

No.

Rate/100,000

No.

Rate/100,000

Nonwhite/White Ratio of Rates

2,832 202 171 198 295 96 655 63 462 265 81 46 42 32 217

8.6 6.4 5.4 7.0 12.4 11.2 9.3 8.3 12.6 10.8 7.4 5.5 4.8 6.2 6.4

3,227 66 583 62 870 0 347 6 906 12 7 5 2 0 359

72.0 60.4 59.6 58.6 92.6

8.4 9.4 11.0 8.4 7.5

*



68.2

7.3



—.

* * • * *

— — — —

99.7

7.9

— 7.5

48.0

* Rates not computed on less than 15 cases. Totals do not add because of rounding in allocation of un­ known race.

TABLE 4 PERSONS ON BLINDNESS REGISTERS DEC. 31, 1970, DUE TO GLAUCOMA BY SEX, RACE, AND AGE (14 MRA STATES)

Age, yrs Tntal*

-

Blindness from glaucoma.

We observed an overall ratio of 8:1 for nonwhite to white primary glaucoma blindness. Our fragmentary evidence suggested that the ratio of underlying ...
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