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Dolly Shuo-Teh Chang, Yuzhen Jiang, Beatriz Munoz, Paul J Foster, Mingguang He, Tin Aung, David S Friedman; Laser iridotomy does not result in cataract progression in primary angle closure suspect eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5573.
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© ARVO (1962-2015); The Authors (2016-present)
Laser peripheral iridotomy (LPI) is performed prophylactically for eyes with narrow angles to prevent acute angle closure attacks. One theoretical risk of this procedure is more rapid development of cataract due to alterations in fluid dynamics and post-laser inflammation. We evaluated the impact of LPI on cataract formation in primary angle closure suspects (PACS) randomized to LPI in one eye only.
Eligible participants with bilateral gonioscopic angle closure of 180 degrees or more were treated by LPI in one randomly selected eye, with the fellow eye serving as its control (trial registered ISRCTN45213099). Cataract was graded at baseline, 18, 36, 54 and 72 months using the Lens Opacity Classification System III for nuclear color (NC), nuclear opalescence (NO), cortical (C) and posterior subcapsular cataract (PSC). Progression was defined as change ≥ 2 grades in any category or cataract surgery. Cox’s proportional hazards model was used to compare time to progression between treated and untreated eyes.
889 participants were randomized and treated with LPI (mean age 59±5 years, 83% female). Lens grading was repeated at 6 month in 10% of participants which showed good agreement in all categories except PSC (intraclass correlation coefficient >0.71 except PSC=0.10). Lens grades and other ocular characteristics were similar between the two eyes at baseline. The average nuclear grades were slightly higher at 72-month among LPI eyes (both NO and NC: 2.9 vs 2.8, p<0.001) but no differences were found for predefined cataract progression (cumulative probability of progression at the end of 72 months: 22.4% in LPI vs. 20.6% in control). The risk of progression in LPI-treated eyes was 8% higher over 6 years [HR=1.08 (95% CI=0.87-1.35)]. Visual acuity at 72 month was similar in treated and untreated eyes at final evaluation (p=0.43).
Prophylactic LPI did not cause significant cataract progression in eyes randomized to treatment in patients with PACS. The randomized design provides strong evidence that treatment of asymptomatic narrow angles with LPI is unlikely to result in negative visual outcomes.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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