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Yuzhen Jiang, Mingguang He, David S Friedman, Tin Aung, Paul J Foster, ZAP Study Group; Longitudinal Changes of Angle Configuration in Primary Angle Closure Suspects: the Zhongshan Angle Closure Prevention Trial. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4294.
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To determine longitudinal changes in angle configuration in eyes of primary angle closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes.
Urban citizens aged 50 to 70 years identified as primary angle closure suspects were enrolled for a randomized controlled clinical trial. Each participant was treated by LPI in one randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months and 18 months after LPI.
No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.49 degrees at baseline to a mean of 25.72 degrees in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months following LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant (P=0.07-1.00). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared to treated eyes (P values for all variables ≤ 0.01). The annual rate of change in angle width was equivalent to 1.17 degrees/year (95% CI: 0.75 degrees/year, 1.60 degrees/year) in treated eyes, and 1.64 degrees/year (95% CI: 1.32 degrees/year, 1.95 degrees/year) in untreated eyes (P< 0.001).
Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by the 18th month following LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period.
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