Changes in Japanese eyes after laser peripheral iridotomy: an anterior segment optical coherence tomography study

Abstract

Background: The aim was to investigate the changes in anterior segment parameters, as assessed by anterior segment optical coherence tomography in Japanese subjects after laser peripheral iridotomy (LPI).

Design: This was a prospective observational study.

Participants: The participants include 72 subjects with angle closure including primary angle closure suspect (PACS), primary angle closure (PAC), and primary angle closure glaucoma (PACG).

Methods: Anterior segment optical coherence tomography parameters was measured by customized software. Complete data of 51 subjects were available for final analysis.

Main outcome measures: These were the following parameters: angle opening distance, trabecular-iris space area, anterior chamber depth, width, area and volume (iris thickness, curvature, and area, and lens vault (LV).

Results: A total of 25 PACS, 17 PAC and 9 PACG were included. Mean age was 74.7 ± 6.7 years, and majority were women (80.4%). Following LPI, there was a significant increase in mean gonioscopic angle width (1.16 vs. 1.93, P < 0.001) and a corresponding increase in angle opening distance, trabecular-iris space area, and angle recess area (all P < 0.001). The anterior chamber area (P < 0.001), anterior chamber volume (P < 0.001) and anterior chamber depth (P = 0.003) increased significantly; and iris curvature (P < 0.001) was significantly reduced. There were no significant changes in anterior chamber width, LV, iris thickness and area. Age-adjusted and gender-adjusted analysis for predictors of percentage change in angle opening distance 750 showed significant association with greater baseline LV (β = 0.32, P = 0.03). No significant differences were noted in the mean percentage change in parameters between the PACS and PAC-PACG.

Conclusions: An increase in anterior chamber dimensions, angle widening and iris flattening; with a constant LV, iris thickness and iris area after LPI was demonstrated in Japanese eyes with angle closure.

Keywords: angle opening distance; anterior chamber depth; anterior segment optical coherence tomography; laser peripheral iridotomy; primary angle closure.