Effects of Laser Peripheral Iridotomy in Subgroups of Primary Angle Closure Based on Iris Insertion

Purpose. To investigate the effect of laser peripheral iridotomy (LPI) in subgroups of primary angle closure based on iris insertion configuration. Methods. Anterior segment optical coherence tomography (AS-OCT) images were obtained before and two weeks after LPI. Qualitative classification of angle closure eyes according to iris insertion (basal insertion group (BG) and nonbasal insertion group (NBG)) was performed. Anterior chamber depth (ACD), lens vault (LV), iris curvature, iris area, iris thickness (IT750), and angle opening distance (AOD750) 750 microns from scleral spur were calculated. Uni- and multivariate regression analysis was carried out to evaluate factors associated with AOD750 before and after LPI. Results. Ninety-two eyes of 92 subjects were categorized as NBG (39 eyes) or BG (53 eyes). The mean change after LPI was not significantly different between two groups in all parameters. In both groups, AOD750 was affected by ACD (p < 0.001, p = 0.044) before LPI. AOD750 was affected by LV (p = 0.012) in NBG, but by ACD (p < 0.001) and IT750 (p = 0.039) in BG after LPI. Conclusions. The outcomes of LPI are not significantly different between angle closure subgroups with different iris insertions. However, factors affecting AOD750 show differences between two subgroups after LPI.