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 Chinese 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 peripheral 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, 0.11-1.77 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.
Glaucoma Center of Excellence, Massachusetts Eye and Ear, Harvard University, Boston, Massachusetts. Electronic address: email@example.com.