The anterior chamber angle is different in different racial groups: a gonioscopic study.

The purpose of the study was to determine racial and sexual differences and age-related changes in the anterior chamber angle to evaluate the reliability of a standardised gonioscopic grading system. The anterior chamber angle was studied prospectively in 291 patients who included Afro-Americans, Caucasians and Far East Asians. No statistically significant difference was found between the angle width of these three groups, but the iris joins the scleral wall more anteriorly in Asians, slightly more posteriorly in Afro-Americans, and most posteriorly in Caucasians (p = 0.03). The anterior chamber tends to be narrower in females (p = 0.002) and to become narrower with increasing age (p < 0.0001) in all ethnic groups. Refractive error significantly affects both the level of iris insertion (p < 0.003) and the angle width (p < 0.001). The consistency of the angle grading system in this project is demonstrated by a close agreement between the examiners. It is concluded that the difference in the angle configuration may account for racial differences in the incidence of angle-closure glaucoma, this being least common in Caucasians, more common in Afro-Americans and most common in Asians.