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Angle-closure glaucoma represents about one fourth of the glaucomas in the world and causes nearly half of all glaucoma blindness. It is asymptomatic in up to 75% of cases (1). Pupillary block is the most common mechanism of angle-closure (2). Known risk factors for pupillary block are older age, female gender, Asian ancestry, narrower drainage angles, smaller anterior segment dimensions, and a thicker and more anteriorly positioned lens. There is however no parameter proven to be sufficiently sensitive to determine whether acute angle-closure will occur (3).
In this context, angle-closure risk evaluation should be performed routinely in all adults undergoing an examination whatever their age or complaints. This holds especially true if they have an abovementioned risk factor, a positive family history of glaucoma, symptoms of subacute intermittent episodes of angle-closure, or when they take α-sympathomimetic or parasympatholytic drugs (3).
Evaluation of the limbal anterior chamber depth (Van Herick technique), and static and dynamic gonioscopy are key (2,3). Given its low risk, prophylactic laser iridotomy is indicated whenever there is a high risk for angle-closure. This corresponds to a positive Van Herick test and net convexity of the iris in the examined subject on gonioscopy, associated with the presence of iridotrabecular contact over 270° or more in primary gaze (3).
Contributor: Michèle Detry
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1. Foster P et al. Angle Closure and Angle Closure Glaucoma. Edited by R. Weinreb. Kruger publications, The Hague, The Netherlands, 2006: 1-20.
2.
Shields’ Textbook of Glaucoma. Fifth Edition 2005; ch 12: 217-34.
3.
Friedman DS et al. Angle Closure and Angle Closure Glaucoma. Edited by R. Weinreb. Kruger publications, The Hague, The Netherlands, 2006: 55-63.
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