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Clinical science
Original article
Increased iris thickness and association with primary angle closure glaucoma
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  1. B-S Wang1,2,
  2. A Narayanaswamy1,
  3. N Amerasinghe1,
  4. C Zheng1,
  5. M He3,
  6. Y-H Chan4,
  7. M E Nongpiur1,
  8. D S Friedman5,
  9. T Aung1,4
  1. 1Singapore Eye Research Institute and Singapore National Eye Center, Singapore
  2. 2Department of Ophthalmology, Beijing Shijitan Hospital, Beijing, China
  3. 3State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
  4. 4Yong Loo Lin School of Medicine, National University of Singapore, Singapore
  5. 5Wilmer Eye Institute and Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
  1. Correspondence to Professor Tin Aung, Glaucoma Service, Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore 168751; tin11{at}pacific.net.sg

Abstract

Aims To investigate the relationship between quantitative iris parameters and angle closure disease.

Methods Participants with angle closure were recruited prospectively from glaucoma clinics. Anterior segment optical coherence tomography (AS-OCT) was performed under standardised dark conditions. Customised software was used on horizontal AS-OCT scans to measure iris thickness at 750 um (IT750) and 2000 um (IT2000) from the sclera spur, maximal iris thickness (ITM) and cross-sectional area of the iris (I-Area).

Results 167 Angle closure (consisting of 50 primary angle-closure (PAC), 73 primary angle closure glaucoma (PACG) and 44 fellow eyes of acute PAC) and 1153 normal participants were examined. After adjusting for age, sex, pupil size and anterior chamber depth, mean IT750 (0.499 vs 0.451 mm, p<0.001), IT2000 (0.543 vs 0.479 mm, p<0.001), ITM (0.660 vs 0.602 mm, p<0.001) and I-Area (1.645 vs 1.570 mm2, p=0.014) were significantly greater in angle closure (combined groups) versus normal eyes. Multivariate adjusted odd ratios (OR) of each parameter for the angle closure as compared with normal eyes were: IT750 OR1.7 (95% CI 1.1 to 2.7, p=0.032); IT2000 OR2.2 (95% CI 1.3 to 3.8, p=0.006) and ITM OR2.2 (95% CI 1.3 to 3.6, p=0.003), respectively, per 0.1 unit increase.

Conclusions Increased iris thickness is associated with angle closure.

  • Anterior chamber
  • angle
  • iris
  • optic nerve
  • epidemiology

https://doi.org/10.1136/bjo.2009.178129

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    Footnotes

    • Funding Grants from Singhealth, Singapore and National Medical Research Council, Singapore.

    • Competing interests Dr T Aung has received research funding, travel support and honoraria from Carl Zeiss Meditec. Dr Friedman has received an instrument loan from Carl Zeiss Meditec.

    • Patient consent Obtained.

    • Ethics approval This study was conducted with the approval of the Singapore Eye Research Institute.

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