Biometric Study of Acute Angle Closure Glaucoma using Orbscan and Echography

Abstract

Abstract: : Purpose: To study the biometry of acute angle closure glaucoma (AACG) using Orbscan and echography. Methods: We prospectively studied 200 normal eyes of 100 patients (including eyes with ametropia), 50 eyes of 25 patients before peripherical YAG laser iridotomy, and 25 phakic eyes of 25 patients with a history of acute angle-closure glaucoma in the fellow eye. We analyzed the irido-corneal angle with both reconstruction modes (plan and polynomial). The biometric measurements (i.e., irido-corneal angle, anterior chamber depth, axial length, and lens thickness) of the 3 groups were compared. The biometric measurements and the subjective spherical equivalent were correlated with the etiologic classification (normal, iridotomy, AACG). Results: Age, sex, irido-corneal angle, anterior chamber depth, lens thickness, axial length and subjective spherical equivalent were significantly different in the 3 groups (p<0.001). The mean value of the angle in the polynomial mode was 43.4° in the normal group, 36.5° in the iridotomy group, and 28.4° in the AACG group (p<0.001). The anterior chamber depth measured by the Orbscan was 3.48 mm in the normal group, 2.60 mm in the iridotomy group and 2.38 mm in the AACG group (p<0.001). The irido-corneal angle correlated with the other biometric measurements (r_s>0.51; p<0.001) and with the etiologic classification (r_s = 0.68; p<0.001). The anterior chamber depth measurement obtained by Orbscan or by echography was the best parameter to predict AACG (r_s = 0.77; p<0.001). Conclusions: The anterior chamber depth and the irido-corneal angle measurements obtained by the Orbscan device appear to be useful to predict acute angle closure glaucoma.

Keywords: anterior chamber • topography • clinical (human) or epidemiologic studies: ris