Change in Angle of Eyes with Primary Angle Closure Suspects One Year after Laser Peripheral Iridotomy : a randomised study

Background: To report the changes in anterior chamber angle and progression rate to PAC(primary angle closure) following laser peripheral iridotomy (LPI) in primary angle closure suspects(PACS).Methods: Prospective, randomized controlled interventional clinical trial conducted at the Handan Eye Hospital, China. 134 bilateral PACS, defined as non-visibility of the posterior trabecular meshwork for ≥ 180 degrees on gonioscopy were randomly assigned to undergo LPI in one eye. Gonioscopy and Goldmann applanation tonometry were performed prior to, on day 7 and 12 months’ post LPI.Results: 80 of 134 patients (59.7%) could be followed up at one year. The mean IOPin treated eyes was 15.9±2.7 mmHg at baseline, 15.4±3.0 mmHg on day 7; 16.5±2.9 mmHg at one month and 15.5±2.9 mmHg at 12 months; the IOP in untreated eyes was similar (p=0.834). One or more quadrants of the angle opened in 93.7% of the LPI treated eyes, but 67.0% (53/79) remained closed in two or more quadrants. The progression rate to PAC in untreated eyes was 3.75% and one developed acute angle closure glaucoma(AACG), the progression rate to PAC(primary angle closure) in treated eyes 2.5% in treated eyes, none had developed PAS or AACG. Conclusion: LPI can open some of the occludable angle in the majority of eyes with PACS, but 67% continue to have non-visibility of the trabecular meshwork for over 180 degrees. IOP remained similar in treated and untreated eyes. Further research is needed to determine the full implications of residual closure as well as the need for follow up and treatment in PACS. The cumulative incidence for PAC/AACG in treated eyes were not significantly different from untreated eyes.Trial registration: Chinese Clinical Trial Registry ChiCTR-TCH-10000820. Registered on 08 April 2010(retrospectively registered).