Acute Angle-Closure Attacks Are Uncommon in Primary Angle-Closure Suspects after Pharmacologic Mydriasis The Zhongshan Angle-Closure Prevention Trial

Purpose: Angle-closure glaucoma is a major cause of blindness worldwide that carries an excessive risk of severe, bilateral visual impairment. A common concern among clinicians is the precipitation of acute angle -closure (AAC) attacks because of mydriasis. We evaluated the risk of AAC after pharmacologic dilation in Chi-nese individuals classified as having bilateral primary angle-closure suspects (PACSs).Design: Randomized, interventional, controlled trial.Participants: A total of 889 patients with bilateral PACSs, aged between 50 and 70 years, were identified through community screening in Guangzhou, China, and enrolled in the study.Methods: In the Zhongshan Angle-Closure Prevention Trial, bilateral PACSs were treated with laser pe-ripheral iridotomy (LPI) in 1 randomly selected eye, with the fellow eye serving as an untreated control. Over 72 months of follow-up, the participants had their pupils pharmacologically dilated 6 times with 5% phenylephrine and 0.5% tropicamide.Main Outcome Measures: Incidence and risk of post-mydriasis AAC in LPI-treated and untreated, control eyes classified as PACSs.Results: One bilateral AAC attack occurred after mydriasis at the 2-week post-LPI visit. No other AAC events occurred in the LPI-treated eyes. In the untreated eyes, 4 additional attacks occurred: 2 occurred after dilation (1 at 54 months and 1 at 72 months of follow-up) and 2 occurred spontaneously. The risk of post-mydriasis AAC in the untreated eyes was 1 attack in 1587 dilations. The risk of spontaneous AAC in the untreated eyes was 0.44 per 1000 eye-years (95% confidence interval, 0.11e1.77 per 1000 eye-years). Conclusions: The risk of incident AAC attacks in PACSs was extremely low, even in a higher-risk group that underwent repeated pharmacologic pupillary dilation over 6 years of follow-up. Prophylactic LPI reduced this small but real risk. This trial was registered at ISRCTN.com as ISRCTN45213099. Ophthalmology Glau-coma 2022;5:581-586 Crown Copyright (c) 2022 Published by Elsevier Inc. on behalf of the American Academy of Ophthalmology