Laser peripheral iridotomy reduces persistent angle closure in primary angle-closure suspects at 5 years

PURPOSE: To evaluate the proportion of patients with, and anatomic predictors of, persistent angle closure 5 years after laser peripheral iridotomy (LPI) in primary angle-closure suspect and to assess anterior segment (AS) anatomic changes over the 5-year follow-up. DESIGN: Subanalysis of randomized controlled trial (the Singapore Asymptomatic Narrow Angles Laser Iridotomy Study). PARTICIPANTS: Of the 480 patients, 375 patients with phakia completed the 5-year follow-up, and 130 patients had complete imaging. METHODS: All patients underwent LPI in 1 randomly selected eye. The proportion of eyes with persistent gonioscopic angle closure (≥ 2 quadrants), its predictors, and the changes in biometric parameters were evaluated. MAIN OUTCOME MEASURES: Odds ratio (OR; with 95% confidence interval [CI]) for predictors. RESULTS: Among 375 participants with 5 years of follow-up, persistent gonioscopic angle closure occurred in 124 LPI-treated eyes (33.1%). At 5 years, LPI significantly reduced the risk of persistent gonioscopic angle closure (OR, 0.12 [95% CI, 0.09-0.17]; P < 0.001). In the imaging cohort (n = 130), 34 eyes (26.2%) had persistent gonioscopic angle closure, a proportion not significantly different from that of the entire cohort (P = 0.17). In multivariable analysis, greater iris thickness measured at 750 μm from the scleral spur (IT750) at baseline (per 0.1 mm; OR, 1.71 [95% CI, 1.21-2.57]; P = 0.004) and younger age at baseline (per 10 years; OR, 0.30 [95% CI, 0.13-0.61]; P = 0.002) were associated with persistent angle closure, whereas lower mean gonioscopic grade was borderline significant (per grade, OR, 0.35 [95% CI, 0.12-1.00]; P = 0.050). Additional analysis showed that greater IT750 was associated significantly with persistent angle closure only in eyes with baseline angle opening distance at 500 μm from the scleral spur below the median (P = 0.005). Angle width (P < 0.001 for all) increased within 2 years after LPI and remained stable thereafter. CONCLUSIONS: In approximately two-thirds of patients, LPI induces sustained angle widening. A thicker iris at baseline in eyes with a narrower angle was predictive of persistent angle closure despite treatment. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.