Purpose To determine whether prophylactic laser peripheral iridotomy (LPI) for primary angle closure (PAC) is associated with cataract progression. Methods In 1999, Mongolian volunteers aged ≥50 years were invited to participate in a longitudinal study. Glaucoma was excluded in all participants and 712 of them were selected to undergo a full ophthalmic examination as part of the study protocol. Lenses were graded and PAC diagnosed using international classification systems. In 2005, all traced participants underwent a similar dilated examination. Diagnosis of cataract progression was based on the inter-observer variation 2 standard deviations. The association between LPI at baseline and cataract progression was assessed using Ξ2 -test and logistic regression. Results Of 712 participants, 158 were diagnosed with occludable angles and treated with LPI. In 2005, 137 participants (19.2%) had died, 315 (315/5755=4.8%) were traced, and dilated examination was performed on 276 (48%) of them. Progression of nuclear opacity (NO), cortical, and posterior subcapsular (PSC) opacities were evident in 40 (14.5%, 95% confidence interval (CI)=10.6-19.2%), 89 (32.2%, 95% CI=26.8-38.1%), and 11 participants (4.0%, 95% CI=2.0-7.0%), respectively. Although NO was more likely to progress in those with LPI in a crude analysis (odds ratio (OR)=2.02, 95% CI=1.00-4.11, P=0.05), no evidence of an independent association was detected in multivariate analysis adjusting for age, sex, and baseline Schaffer grading (adjusted OR1.24, 0.41-3.75, P0.7). There was no evidence of an association between LPI and progression of PSC or cortical opacities. Conclusions There is no evidence that prophylactic LPI is independently associated with cataract progression in this study.
Bibliographical noteFunding Information:
We would like to thank Drs Davaasambuu Tsendenkhuu and Tsedendavaa, Chimed Oyunsuren, Tsedengonbo Lhagvasuren, Dr Tsagaan Altantsetseg from Sukbaator District hospital, and Dr Legtsegdulam Altantsetseg from Bayanzurkh District hospital, the staff of Sukbaator District hospital, Bayanhongor hospital, and Bolor Melmii who worked on this project. This work was funded by the Wellcome Trust, British Council for Prevention of Blindness (London), Christian Blind Mission (CBM) (Bensheim), The National Lotteries Fund through Fight for Sight (London). The Yag laser used in this study was donated by the Velux Foundation, Copenhagen. We acknowledge a proportion of our financial support from the Department of Health through the award made by the National Institute for Health Research to Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology for a Specialist Biomedical Research Centre for Ophthalmology. The views expressed in this publication are those of the authors and not necessarily those of the Department of Health.
- glaucoma (angle closure)
- laser therapy