A method is described which allows prediction of the anterior angle landmarks that are likely to be visible by gonioscopy from a slitlamp assessment of anterior chamber width at the limbus. This prediction can assist the recognition of gonioscopic features when the angle presents difficulties of identification and can also help clinicians who are learning the technique of gonioscopy. It may be used as a screening procedure to select those eyes in which the angle is sufficiently narrowed that gonioscopic examination should be performed. It was found that slitlamp estimates of 0.2 corneal units or less indicate a narrowing of the angle sufficient to warrant gonioscopic assessment and that estimates of 0.3 units should be considered to be the threshold of risk of angle closure.