THE ROLE OF ETHNICITY IN PRIMARY ANGLE-CLOSURE GLAUCOMA

Primary angle-closure glaucoma is significantly more common than prima ry open-angle glaucoma in the East, whereas in Africa and Europe the r everse is true. In order to study the role of ethnic background in the frequency of primary angle-closure glaucoma in Cape Town and, in part icular, 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-mon th period. Primary angle-closure glaucoma was diagnosed in 11 of 63 (1 7%) whites, 11 of 85 (13%) blacks and 114 of 244 (46,7%) coloureds wit h primary glaucoma; the difference is statistically highly significant (P < 0,001). The human leucocyte antigen frequencies in 97 coloured p atients with primary angle-closure glaucoma were similar to those foun d 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.