Comparison of Fellow Eyes of Acute Primary Angle Closure and Phacomorphic Angle Closure.

Purpose: To compare anterior segment parameters in fellow eyes of acute primary angle closure (APAC) and fellow eyes of phacomorphic angle closure (AC) and to identify parameters that could be used to differentiate fellow eyes of the 2 entities. Methods: This cross-sectional study included 55 unaffected fellow eyes of APAC, 48 unaffected fellow eyes of phacomorphic AC, and 52 eyes of control subjects. All patients underwent anterior segment optical coherence tomography imaging. Anterior chamber depth, anterior chamber area, anterior chamber width (ACW), iris thickness (IT), iris curvature, lens vault (LV), and angle parameters including angle-opening distance (AOD750) were measured in qualified images using customized software and compared among the groups using a linear mixed model. Results: Fellow eyes of APAC had the smallest axial length, AOD, anterior chamber depth, anterior chamber area, ACW, and the greatest LV, and IT (P <= 0.002 for all), followed by fellow eyes of phacomorphic AC, after adjustment for age, sex, and pupil diameter. IT and curvature were comparable between fellow eyes of phacomorphic AC and controls. Angle parameters had the highest area of the receiver-operator characteristic curve for discrimination of fellow eyes of APAC eyes and phacomorphic AC (0.795, P=0.001 for AOD750). In a multivariable analysis, AOD750<0.161 mu m [odds ratio (OR), 23.43; P=0.001], LV>768.6 mu m (OR, 16.76; P=0.001), ACW<11.07 mm (OR, 8.93; P=0.023) and younger age (P=0.001) were the factors that discriminated fellow eyes of APAC from phacomorphic AC. Conclusions: Differences in ocular biometric parameters can be detected between fellow eyes of APAC and phacomorphic AC. Narrower angle, more anteriorly displaced lens, and thicker iris are the main parameters that distinguish fellow eyes of APAC and phacomorphic AC.