Relative risk of blindness and MSVI nationally by age 1986, 1996 and 2019
| Sample examined | Blindness (crude) | MSVI (crude) | |||||||
| 1986 | 1996 | 2019 | 1986 | 1996 | 2019 | 1986 | 1996 | 2019 | |
| Age | n | n | n | % | % | % | % | % | % |
| 30–39† | 807 | 1303 | 2249 | 0.4 | 0.4 | 0.1 | 0.9 | 0.4 | 1.2 |
| 40–49 | 590 | 842 | 3096 | 1.0 | 0.2 | 0.3 | 1.9 | 2.1 | 2.7 |
| 50–59 | 407 | 496 | 1741 | 1.5 | 1.9 | 0.6 | 4.2 | 6.5 | 8.0 |
| 60–69 | 255 | 369 | 1154 | 3.9 | 3.5 | 1.2 | 8.6 | 12.1 | 18.0 |
| 70+ | 226 | 278 | 948 | 9.7 | 7.5 | 7.1 | 19.9 | 28.1 | 37.6 |
| Crude prevalence | 2.1 (1.5 to 2.6) | 1.5 (1.1 to 2.0) | 1.2 (0.9 to 1.4) | 4.5 (3.6 to 5.3) | 5.4 (4.7 to 6.2) | 8.9 (8.3 to 9.5) | |||
| Age-standardised prevalence‡ | – | 1.7 (1.2 to 2.1) | 1.1 (0.9 to 1.3) | – | 6.0 (5.2 to 6.8) | 8.3 (7.9 to 8.8) | |||
| Risk ratio (compared with 1986)§ | – | 0.8 (0.6 to 1.2) | 0.5** (0.3 to 0.7) | – | 1.3* (1.0 to 1.6) | 1.9** (1.6 to 2.3) | |||
| Risk difference (compared with 1986)¶ | – | −0.004 (−0.011 to 0.003) | −0.009 (−0.015 to −0.003) | – | 0.135 (0.002 to 0.025) | 0.387 (0.029 to 0.048) | |||
| Risk ratio (compared with 1996)§ | – | 0.7* (0.5 to 1.0) | – | 1.5 (1.2 to 1.7)** | |||||
| Risk difference (compared with 1996)¶ | – | −0.005 (−0.010 to −0.000) | – | 0.252 (0.016 to 0.346) | |||||
NB 1996 and 1986 comparison data generated from unpublished survey data provided by H Faal.
*p<0.05 from χ2 test.
†35–39 in 2019.
‡Age standardised to 1986 sample.
§Age-standardised prevalence risk ratio.
¶Age-standardised prevalence risk difference.
**p<0.001 from χ2 test.
MSVI, moderate or severe vision impairment.