The role of ethnicity in primary angle-closure glaucoma.

Primary angle-closure glaucoma is significantly more common than primary open-angle glaucoma in the East, whereas in Africa and Europe the reverse is true. In order to study the role of ethnic background in the frequency of primary angle-closure glaucoma in Cape Town and, in particular, in people of mixed ethnic background, the so-called 'coloureds', we retrospectively reviewed all patients with primary glaucoma who attended the glaucoma clinic at Groote Schuur Hospital during a 30-month period. Primary angle-closure glaucoma was diagnosed in 11 of 63 (17%) whites, 11 of 85 (13%) blacks and 114 of 244 (46.7%) coloureds with primary glaucoma; the difference is statistically highly significant (P < 0.001). The human leucocyte antigen frequencies in 97 coloured patients with primary angle-closure glaucoma were similar to those found in a control group of individuals with a similar ethnic background. This study highlights the fact that coloureds are more predisposed to primary angle-closure glaucoma than whites or blacks. Because of their strong historical and genetic ties with south-east Asia, this greater prevalence of primary angle-closure glaucoma might be explained by an Eastern influence on the ocular structures of the eye, as opposed to an African or European influence.