April 2009
Volume 50, Issue 13
Free
ARVO Annual Meeting Abstract  |   April 2009
Increased Iris Thickness and Curvature Are Risk Factors for Angle Closure
B. Wang; L. M. Sakata; Y. H. Chan; M. He; R. Lavanya; D. S. Friedman; T. Y. Wong; T. Aung
Author Affiliations & Notes
  • B. Wang
    Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore
  • L. M. Sakata
    Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore
  • Y. H. Chan
    Biostatistics Unit, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
  • M. He
    State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
  • R. Lavanya
    Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore
  • D. S. Friedman
    Wilmer Eye Institute and Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
  • T. Y. Wong
    Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore
  • T. Aung
    Singapore National Eye Centre, Singapore Eye Research Institute, Singapore, Singapore
  • Footnotes
    Commercial Relationships  B. Wang, None; L.M. Sakata, None; Y.H. Chan, None; M. He, Carl-Zeiss Meditec, F; R. Lavanya, None; D.S. Friedman, Carl-Zeiss Meditec, F; T.Y. Wong, None; T. Aung, Carl-Zeiss Meditec, F; Carl-Zeiss Meditec, R.
  • Footnotes
    Support  Grant from Singhealth, Singapore
Investigative Ophthalmology & Visual Science April 2009, Vol.50, 3358. doi:
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      B. Wang, L. M. Sakata, Y. H. Chan, M. He, R. Lavanya, D. S. Friedman, T. Y. Wong, T. Aung; Increased Iris Thickness and Curvature Are Risk Factors for Angle Closure. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3358.

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Abstract

Purpose: : To investigate the relationship between iris parameters and risk of angle closure (AC).

Methods: : This cross-sectional observational study included 2047 subjects over 50 years old recruited from a community clinic in Singapore. All subjects underwent gonioscopy and AS-OCT imaging under identical standardized conditions. Gonioscopy was performed by a single masked examiner in the dark, and AC was defined as the presence of at least 180 degrees of angle in which the posterior pigmented trabecular meshwork was not visible on non-indentation gonioscopy in the primary position. AS-OCT imaging in the dark was performed by a single masked operator using the commercially available Visante-OCT (Carl-Zeiss Meditec, Dublin/USA). Customized software was used on horizontal ASOCT scans to measure the following iris parameters: iris thickness 750um (IT750) and 2000 um (IT2000) from the sclera spur, iris curvature (I-Curv) and cross-sectional area of the iris (I-Area). The right eye of all subjects and an average of both temporal and nasal measured values were used for analysis.

Results: : Participants were excluded mainly due to poor AS-OCT image quality or poor definition of the scleral spur. Iris parameters from 1465 eyes were available for analysis. Of these, 315 subjects (21.5%) had AC on gonioscopy. Mean I-Curv (0.366mm v 0.259mm, p<0.001), IT750 (0.476mm v 0.453, p<0.001) and IT2000 (0.491mm v 0.482mm, p=0.020) were greater in those with than without AC. After adjusting for age, gender, body-mass index, anterior chamber depth and axial length, greater I-Curv, IT750 and IT2000 remained significantly associated with AC (4th vs 1st quartile, multivariate adjusted OR 2.5, 95%CI 1.3-5.1; OR 3.0, 95% CI 1.9-4.7 ; OR 3.7, 95% CI 2.2-6.3 respectively) while I-Area was not significant (OR 1.3, 95% CI 0.8-2.1).

Conclusions: : Our findings show that iris curvature and thickness are risk factors for angle closure even after adjusting for other known ocular risk factors.

Keywords: iris • imaging/image analysis: clinical • anterior segment 
© 2009, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2025 Association for Research in Vision and Ophthalmology.
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