Anterior Segment Dimensions Following Laser Iridotomy in Acute Primary Angle Closure and Fellow Eyes

Abstract

To compare the change in anterior segment morphology after laser peripheral iridotomy (LPI) in acute primary angle closure (APAC) and their fellow eyes. Prospective, fellow eye-matched case series. In this study 42 individuals with unilateral episode of APAC were enrolled and the anterior segment optical coherence tomography (ASOCT) images were obtained in both eyes at baseline and at 6weeks after LPI. A linear mixed-effects model was used to compare changes in anterior chamber and angle variables with consideration of laterality as the random effect and pupil diameter as the fixed effect. APAC eyes had smaller angle parameters (P= .013 for all), less central anterior chamber depth (cACD) (P < .001), and lower anterior chamber area (ACA) (P < .001), as well as greater lens vault (LV) (P= .007), compared with fellow eyes. LPI resulted in angle widening with a significant increase in opening distance (P < .01 for all) in both APAC and fellow eyes. cACD (P= .003) and ACA (P < .001) increased and LV (P= .002) decreased in APAC eyes. However, there was no significant change in cACD (P= .190) and LV (P= .430) in fellow eyes. In both APAC eyes and fellow eyes, iris curvature decreased after LPI (P < .001). The changes in angle parameters, ACA, and iris curvature were not significantly different between the 2 groups. In APAC eyes and their fellow eyes, LPI resulted in significant anterior chamber angle widening and increased anterior chamber area. In APAC eyes, the iris flattened, cACD deepened, and the lens shifted posteriorly after resolution of the attack. However, in fellow eyes, the increase in ACA was mainly owing to decreased iris curvature.