Prevalence of blindness and low vision of people over 30 years in the Wenchi district, Ghana, in relation to eye care programmes.

A population based survey on the prevalence of major blinding disorders was conducted in the Wenchi district in central Ghana between March and May 1991. In 10 villages, 1425 people of 30 years and older were screened, using the WHO eye examination record. The prevalence of bilateral blindness above 30 years proved to be 1.7% (best acuity < 3/60): the prevalence of low vision above 30 years was 2.0% (best visual acuity 6/18 to 3/60). The causes of blindness were determined as cataract (62.5%), onchocerciasis (12.5%), corneal opacity (non-trachomatous) (8.2%), refraction anomalies (4.2%), phthisis bulbi (4.2%), optic atrophy (4.2%), and vascular retinopathy (4.2%). In the Wenchi district, 1.0% of the population over the age of 30 years was found to need a cataract extraction because of blindness of both eyes. Another potential 1.0% needs a cataract extraction because of low vision. A minor second study (n = 149) was undertaken in the same district, but in a village in an area near the Black Volta river in which onchocerciasis is endemic. The prevalence of blindness (8.1%) and low vision (3.4%) caused by onchocerciasis and cataract both proved to be higher. The survey provided the basis for a preventive and curative eye care programme.