Table 5.
Ten-year incidence of best corrected visual impairment and blindness stratified by age at baseline in participants.
| Age at baseline (years) | Incidence of visual impairment | Incidence of blindness | ||||
|---|---|---|---|---|---|---|
| N | n | % (CI) | N | n | % (CI) | |
| United States Criterion* | ||||||
| < 40 | 34 | 4 | 11.8 (4.7, 29.5) | 40 | 6 | 15 (7.2, 31.4) |
| 40–49 | 91 | 17 | 18.7 (12.2, 28.7) | 103 | 15 | 14.6 (7.2, 18.6) |
| 50–59 | 164 | 28 | 17.1 (12.2, 23.9) | 191 | 26 | 13.6 (9.5, 19.5) |
| 60–69 | 81 | 16 | 19.8 (13.7, 30.6) | 87 | 8 | 9.2 (4.8, 17.8) |
| 70 + | 3 | 1 | 33.3 (6.7, 165.1) | 4 | 0 | NA |
| p = 0.39 | p = 0.22 | |||||
| Crude overall | 373 | 66 | 17.7 (14.2, 22.0) | 425 | 55 | 12.9 (9.5, 15.6) |
| WHO Criterionφ | ||||||
| < 40 | 38 | 4 | 10.5 (4.2, 26.6) | 41 | 3 | 7.3 (2.5, 21.8) |
| 40–49 | 98 | 13 | 13.3 (8.0, 22.0) | 107 | 8 | 7.5 (3.8, 14.6) |
| 50–59 | 181 | 21 | 11.6 (7.8, 17.3) | 196 | 16 | 8.2 (5.1, 13.0) |
| 60–69 | 85 | 7 | 8.2 (4.0, 16.7) | 93 | 7 | 7.5 (3.7, 15.3) |
| 70 + | 3 | 0 | NA | 4 | 0 | NA |
| p = 0.40 | p = 0.96 | |||||
| Crude overall | 405 | 45 | 11.1 (8.4, 14.6) | 441 | 34 | 7.7 (5.6, 10.6) |
N = number at risk at baseline; n = incident cases; % (CI) = prevalence and 95 percent confidence interval; p value calculated using test of trend; Number of observations = 455.
U.S. Criterion*. Incidence of visual impairment: Person with Baseline best corrected visual acuity (BCVA) of 6/12 or better in better seeing-eye, and follow-up BCVA worse than 6/12 but better than 6/60 (not including 6/12 or 6/60) in better seeing-eye. Incidence of Blindness: Persons with Baseline BCVA better than 6/60 in the better Seeing Eye and follow-up BCVA 6/60 or worse (including 6/60).
W.H.O. Criterionφ. Incidence of visual impairment: Incidence of visual impairment: Persons with Baseline BCVA 6/18 or better in better seeing-eye and follow-up BCVA worse than 6/18 but better than or equal to 3/60 (not including 6/18 but including 3/60) in the better seeing-eye. Incidence of Blindness: Persons with Baseline BCVA 3/60 or better in better seeing-eye and follow-up BCVA worse 3/60 (not including 3/60) in better seeing-eye.
NA No incident cases.