Anterior chamber depth measurement as a screening tool for primary angle-closure glaucoma in an East Asian population

Abstract

Objective: To evaluate anterior chamber depth measurement as a method of screening for primary angle-closure glaucoma in an East Asian population.

Design: Two-phase, cross-sectional, community-based study.

Setting: Rural and urban locations in the Hovsgol and Omnogobi provinces, Mongolia.

Participants: Nine hundred forty-two (94.2%) of 1000 individuals in Hovsgol(1995) and 775 (96.9%) of 1000 individuals in Omnogobi (1997) aged 40 years or older were examined.

Main outcome measures: Anterior chamber depth was measured by optical pachymetry, slitlamp-mounted A-mode ultrasound, and handheld ultrasound. Gonioscopy was used to detect occludable angles, defined as one in which the trabecular meshwork was visible for less than 90 degrees of angle circumference. Primary open-angle glaucoma was diagnosed in subjects with an occludable angle and glaucomatous optic neuropathy with visual morbidity. The area under the curve in a receiver operating characteristic plot was used to compare test performance.

Results: Optical pachymetry outperformed the slitlamp-mounted ultrasound method of anterior chamber depth measurement (area under the curve, 0.93 and 0.90, respectively; z test, P = .001). Handheld ultrasound (area under the curve, 0.86) was inferior to optical measurement (z test, P = .001) but did not differ significantly from slitlamp ultrasound (z test, P = .06). The optical method gave sensitivity of 85% and specificity of 84% at a screening cutoff of less than 2.22 mm for detecting occludable angles.

Conclusions: Measurement of axial anterior chamber depth can detect occludable angles in this Asian population and therefore may have a role in population screening for primary angle-closure glaucoma.