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Cataract progression after Nd:YAG laser iridotomy in primary angle-closure suspect eyes
  1. Dolly Shuo-Teh Chang1,2,
  2. Yuzhen Jiang3,
  3. Julia Anne Kim2,
  4. Shengsong Huang3,
  5. Beatriz Munoz4,
  6. Tin Aung5,
  7. Mingguang He3,
  8. Paul J Foster6,
  9. David Friedman7
  1. 1 Ophthalmology, Byers Eye Institute, Stanford University, Palo Alto, California, USA
  2. 2 gRED ECD OMNI, Genentech Inc, South San Francisco, California, USA
  3. 3 State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, People's Republic of China
  4. 4 Wilmer Eye Institute, Johns Hopkins University, Baltimore, Maryland, USA
  5. 5 Singapore Eye Research Institute and Singapore National Eye Centre, Singapore Yong Loo Lin School of Medicine, National University of Singapore, Singapore
  6. 6 NIHR Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, UK
  7. 7 Glaucoma Center of Excellence, Massachusetts Eye and Ear, Harvard University, Boston, Massachusetts, USA
  1. Correspondence to Dr Mingguang He, State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, People's Republic of China; mingguang_he{at}


Background/Aims Prophylactic laser peripheral iridotomy (LPI) is performed in primary angle-closure suspect (PACS) eyes to prevent acute angle-closure attacks. However, accelerated cataractogenesis is a potential risk of the procedure that may result in decreased visual acuity. We aimed to assess the long-term impact of LPI on cataract formation in Chinese PACS.

Methods In the Zhongshan Angle Closure Prevention Trial, eligible bilateral PACS participants received LPI in one randomly selected eye, while the fellow eye remained untreated. Cataract was graded using the Lens Opacity Classification System III, and progression was defined as an increase in grade by at least two units in any category or cataract surgery.

Results In total, 889 participants were randomly assigned to LPI in one eye only (mean age 59±5 years, 83% female). At 72 months, treated eyes had slightly higher average nuclear grades (p<0.001). However, there were no differences between eyes for predefined cataract progression (cumulative probability at 72 months: 21.2% in LPI vs 19.4% in control, p=0.401) or cataract surgery (1% for both). While LPI-treated eyes had a 10% higher risk of progression over 6 years (HR=1.10 (95% CI 0.88 to 1.36)), this was not statistically significant. Visual acuity at 72 months was similar in treated and untreated eyes (p=0.43).

Conclusion Although lenses were graded on average as slightly more opaque in laser-treated eyes, prophylactic neodymium:yttrium-aluminum-garnet LPI did not cause significant cataract progression. Our results suggest that LPI treatment of asymptomatic narrow angles does not increase the risk of developing clinically meaningful cataract worsening over time.

Trial registration number ISRCTN45213099.

  • Glaucoma
  • Angle
  • Clinical Trial
  • Treatment Lasers
  • Vision

Data availability statement

Data are available on reasonable request. The datasets generated and/or analysed during the current study are available from PJF (, DF ( and MH ( on reasonable request.

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Data availability statement

Data are available on reasonable request. The datasets generated and/or analysed during the current study are available from PJF (, DF ( and MH ( on reasonable request.

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  • Presented at The Association for Research in Vision and Ophthalmology Annual Meeting, 2017.

  • Contributors MH, PJF and DF conceived and designed the trial. MH, TA, PJF and DF were the chief investigators and oversaw the trial throughout. YJ and SH were trial examiners. DS-TC and BM monitored the data, performed analyses and provided critical feedback to study design and activities. All authors contributed to the interpretation of data and decided on the content of the manuscript. DS-TC and JAK drafted and critically revised the manuscript for important intellectual content. All authors approved the final version. Guarantor: DF.

  • Funding This work is supported by the Fight for Sight (grant no. 1655; UK), the Sun Yat-sen University 5010 Project Fund (grant no. 2007033; China), the National Natural Science Foundation of China (grant no. 81420108008; China) and Fundamental Research Funds of the State Key Laboratory in Ophthalmology (no award/grant no.; China). MH receives support from the University of Melbourne Research at Melbourne Accelerator Program Professorship. The Centre for Eye Research Australia receives operational infrastructural support from the Victorian government. YJ and PJF are supported by a grant from the British Council for Prevention of Blindness (UK). PJF received additional support from the National Institute for Health Research (NIHR) Biomedical Research Centre at Moorfields Eye Hospital, London, UK (NIHR-BRC2 009; Moorfields/UCL-IOO), Special Trustees of Moorfields Eye Hospital (since renamed Moorfields Eye Charity), and the Richard Desmond Charitable Foundation (via Fight for Sight, UK).

  • Disclaimer These funding sources did not play any role in the design and conduct of the study; in the collection, management, analysis, or interpretation of the data; or in the preparation, review, approval of the manuscript, or decision to submit the manuscript for publication.

  • Competing interests DS-TC and JAK are employees of Genentech Inc.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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