Table 1.
Community-based cross-sectional studies reporting prevalence of diabetic retinopathy in Africa
| Study | Methods | Subjects and subgroups | n | Outcome |
||
|---|---|---|---|---|---|---|
| Any diabetic retinopathy, % (95% CI) | Proliferative diabetic retinopathy (%) | Maculopathy (%) | ||||
| Studies reporting prevalence of diabetes and diabetic retinopathy in the general population | ||||||
| Egypt, 1991–1994 [8,34,41,42] | Stratified random sampling of persons ≥ 20 years in urban and rural areas near Cairo. 4620 adults underwent random glucose testing. Those at high risk of diabetes and a sample of those at low risk (total 1451) had a fasting glucose test. Diabetes diagnosed by World Health Organization criteria (see also Supporting Information, Appendix S1 [101]). Retinal photography graded according to Airlie House Classification and binocular indirect ophthalmoscopy examination by ophthalmologist. Those ungradeable on photography and binocular indirect ophthalmoscopy excluded from analysis of retinal photography and binocular indirect ophthalmoscopy, respectively | Subjects with diabetes (retinal photography)* | 335 | 31.6 | 0.9 | 4.5‡ |
| Subjects with diabetes (binocular indirect ophthalmoscopy)* | 404 | 20.3 | 0 | 1.2‡ | ||
| Known diabetes (retinal photography)† | 287 | 41.5 (35.8–47.2) | ||||
| Newly diagnosed diabetes (retinal photography)† | 89 | 15.7 (8.2–23.3) | ||||
| Impaired glucose tolerance (retinal photography)† | 103 | 1.9 (0–4.6) | ||||
| Mauritius, 1992 [7] | 6553 persons in 14 geographically defined clusters underwent glucose tolerance test. In 11 clusters, all adults aged 25–74 years were invited to attend; in three clusters, age-stratified sampling of adults aged 35–64 years performed. Those with diabetes and 25% of those with impaired glucose tolerance [World Health Organization criteria (115)] had 3-field, 45° stereoscopic retinal photography of the right eye. Grading by certified assessor according to modified Airlie House criteria. Those with ungradeable photographs were excluded from analysis | All subjects with diabetes | 746 | 30.2 (26.9–33.5) | 1.3 | |
| Known diabetes | 388 | 44.3 (39.4–49.2) | 2.3 | |||
| Newly diagnosed diabetes | 358 | 14.8 (11.1–18.5) | 0.3 | |||
| Impaired glucose tolerance | 165 | 9.1 (4.7–13.5) | 0 | |||
| Muslim Indian race with diabetes | 186 | 22.8 (18.7–28.9) | 1.1 | |||
| Creole race with diabetes | 160 | 35.7 (28.1–43.3) | 1.3 | |||
| Study of cause of visual impairment in the general population | ||||||
| Nigeria, 2005–2007 [9] | National multistage, stratified cluster sampling of persons ≥ 40 years to determine cause of visual impairment. 13 591 visual acuity tested; 3129 had uncorrected visual acuity < 6/12 in better eye examined by ophthalmologist. Primary cause of visual impairment recorded | Subjects with visual acuity < 6/12 better eye | 3129 | 0.29 | ||