Dynamic Changes in Anterior Segment (AS) Parameters in Eyes with Primary Angle Closure (PAC) and PAC Glaucoma and Open-Angle Eyes Assessed Using AS Optical Coherence Tomography

Abstract

To evaluate serial changes in anterior segment (AS) parameters in terms of variation in pupil diameter (PD) using AS optical coherence tomography (OCT) in eyes with primary angle closure or primary angle closure glaucoma (PCG), age-matched open-angle (AO) eyes, and young open-angle (YO) eyes. Forty-four PCG (mean ± SD; 62.2 ± 7.5 years), 36 AO (62.0 ± 12.3 years), and 58 YO eyes (29.1 ± 7.0 years) were imaged under four standardized lighting conditions (3.25, 100.8, 426, and 1420 cd/m(2)). PD, anterior chamber depth (ACD), iris cross-sectional area (IA), iris thicknesses at 750 and 1500 μm from the scleral spur (IT750, IT1500), iris curvature (IC), lens vault (LV), and anterior chamber area (ACA), were calculated. The slope of the change in each AS parameter in terms of variation in PD was determined by a linear mixed-effect model. The mean ACD was significantly shallower (P < 0.001), the IC higher (P < 0.001), the IT750 greater (P = 0.026), the ACA smaller (P < 0.001), the LV greater (P < 0.001), and the IA wider (P = 0.019) in PCG eyes compared with AO eyes. However, the mean slope of no parameter differed significantly between PCG and AO eyes. The mean slopes of IC, IT1500, and IA differed between AO and YO eyes. Older eyes showed significantly different dynamic AS parameter responses in terms of change in PD compared with younger eyes. Thus, the authors suggest that changes in the dynamic features of AS parameters with age may contribute to angle closure development, in addition to any predisposing anatomic condition.