Residual Angle Closure One Year After Laser Peripheral Iridotomy in Primary Angle Closure Suspects.

PURPOSE: To determine the incidence and baseline clinical and anterior segment optical coherence tomography (AS-OCT) predictors associated with residual angle closure as assessed by gonioscopy 1 year after laser peripheral iridotomy (LPI) in primary angle closure suspects (PACS). DESIGN: Subanalysis of randomized controlled trial data. METHODS: AS-OCT images from 181 PACS subjects ≥50 years of age were analyzed using customized software before and 1 year after LPI. Other parameters assessed were intraocular pressure (IOP) and axial length (Axl). Residual angle closure was defined as the inability to see the posterior trabecular meshwork for at least 2 quadrants on gonioscopy after LPI. Multivariate regression analysis determined the baseline predictors of residual angle closure 1 year after LPI. RESULTS: The mean age of participants was 62.4 (standard deviation 9.9) years. The majority were female (137, 75.7%) and Chinese (174, 96.1%). At 1 year post LPI, 148 (81.8%) subjects had gonioscopic residual angle closure. Univariate analysis showed that baseline Axl, anterior chamber area, anterior chamber volume, angle opening distance at 750 µm from the scleral spur, and angle recess area were smaller while baseline lens vault and iris curvature were larger in residual angle closure subjects (all P < .05). Multivariate analysis revealed that baseline iris volume (B = -0.08, P = .035) and baseline IOP (B = 0.23, P = .032) were predictors for residual angle closure. CONCLUSIONS: One year after LPI, >80% of PACS had gonioscopic residual angle closure. Greater baseline iris volume and higher IOP at baseline are independent risk factors for residual gonioscopic angle closure.