Table 3
Distribution of causes of visual loss by visual loss category at round 2 among people who passed screening at round 1: estimated incidence rates stratified by age and by visual loss category and cause of visual loss
| Causes | Bilateral blindness | Bilateral visual impairment | Unilateral blindness | Unilateral visual impairment | Total (PY) | Rate/1000 PY (95% CI)* |
|---|---|---|---|---|---|---|
| Age stratified incidence: | ||||||
| 13–34 | 0 | 0 | 2 | 2 | 4 (3301) | 1.21 (0.33 to 3.10) |
| 35–54 years | 0 | 3 | 2 | 6 | 11 (1482) | 7.42 (3.71 to 13.3) |
| 55–64 years | 0 | 7 | 1 | 5 | 13 ( 462) | 28.1 (14.5 to 48.1) |
| 65 years and older | 1 | 11 | 7 | 9 | 28 ( 436) | 64.2 (42.7 to 92.7) |
| Specific causes | ||||||
| Cataract | 0 | 11 | 6 | 6 | 23 (5682) | 4.05 (2.57 to 6.07) |
| Refractive error | 0 | 2 | 0 | 5 | 7 (5682) | 1.23 (0.50 to 2.54) |
| Macular degeneration | 0 | 0 | 1 | 2 | 3 (5682) | 0.53 (0.11 to 1.54) |
| Chorioretinitis | 1 | 2 | 0 | 0 | 3 (5682) | 0.53 (0.11 to 1.54) |
| Glaucoma | 0 | 2 | 0 | 0 | 2 (5682) | 0.35 (0.04 to 1.27) |
| Corneal opacity | 0 | 0 | 1 | 1 | 2 (5682) | 0.35 (0.04 to 1.27) |
| Other cause† | 0 | 0 | 3 | 4 | 7 (5682) | 1.23 (0.50 to 2.54) |
| Cause not determined | 0 | 4 | 1 | 4 | 9 (5682) | 1.58 (0.72 to 3.01) |
| Total | 1 | 21 | 12 | 22 | 56 (5682) | 9.86 (7.44 to 12.8) |
| Rate/1000 PY* | 0.18 (0.00 to 0.98) | 3.70 (2.29 to 5.65) | 2.11 (1.09 to 3.69) | 3.87 (2.43 to 5.86) | ||
| Expected cases/year† | Bilateral blindness and bilateral visual impairment | Unilateral blindness | Unilateral visual impairment | Total |
|---|---|---|---|---|
| *Rates based on 1997 people who passed screening test at round 1 and 56 cases identified at round 2. | ||||
| †Expected number of cases based on (a) an estimated total population for Uganda of 24.6 million (CIA-World Fact Book, updated Jan 2002) and (b) the proportion of the population in each age stratum reported in The Uganda Health and Demographic Survey of 1991. The single incident case of bilateral blindness is included with incident cases of bilateral visual impairment because of the imprecision of any estimate based on a single case. | ||||
| ‡Up to date population estimates were not available for exactly the same strata as those used for the study; the tabulated estimates are based on incidence rates for the age stratum 13–34 years observed in the study and a denominator derived from the sources described above for the age stratum 15–34. | ||||
| 15–34‡ | 0 | 4940 | 4940 | 9880 |
| 35–54 | 5476 | 3651 | 10952 | 20078 |
| 55–64 | 10654 | 1522 | 7610 | 19786 |
| 65 years and older | 14218 | 8294 | 10664 | 33176 |
| Total | 30348 | 18407 | 34166 | 82920 |
