Prevalence and causes of visual impairment in Fundong district, North West Cameroon: results of a population-based survey

Summary

The purpose of the study was to estimate the prevalence and causes of visual impairment in Fundong Health District, north-west Cameroon. A total of 51 clusters of 80 people (all ages) were sampled with probability proportionate to size and compact segment sampling. Visual acuity (VA) was measured with a ‘tumbling E’ chart. An ophthalmic nurse examined people with VA<6/18 in either eye.

The presence of hearing and physical impairments were assessed using clinical examination, and self-reported visual problems using the Washington Group Short Set of questions on disability. In total, 4,080 people were enumerated, of whom 3,567 were screened (response rate 87%). The overall prevalence of visual impairment was 2.3% (95% CI 1.8–3.0%) and blindness was 0.6% (0.3–1.0%). The prevalence of both blindness and visual impairment increased rapidly with age, so that the vast majority of cases of visual impairment (84%) and blindness (82%) were in people aged 50+.

Posterior segment disease and cataract were the main causes of blindness and visual impairment, with refractive error also an important cause of visual impairment. Cataract surgical coverage (proportion of all cataracts that had received surgery) was relatively high (87% of people at VA<6/60). Post-surgery outcomes were poor, with 31% of operated eyes having VA<6/60. Among the 82 people with visual impairment, 22% had a physical impairment or epilepsy and 30% had a hearing impairment.

Self-reported difficulties in vision were relatively closely related to clinical measures of visual impairment. Ophthalmic programmes in Cameroon need to incorporate control of posterior segment diseases while also working to improve outcomes after cataract surgery.