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Editors Selection IGR 16-4

Angle-closure glaucoma: Identification of high risk groups

Comment by Jeffrey Liebmann & Christopher Teng on:

21321 Determinants of angle closure in older Singaporeans, Lavanya R; Wong TY; Friedman DS et al., Archives of Ophthalmology, 2008; 126: 686-691

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Angle closure glaucoma remains a leading cause of blindness, especially in Asian populations. Since screening entire populations for angle closure (AC) is impractical, it is important to identify high risk groups that may be targeted for glaucoma screening and blindness prevention efforts. Lavanya et al. (733) performed a cross-sectional study of patients from a primary care clinic in Singapore, with each subject completing a questionnaire and having refraction, biometry and gonioscopy. Gonioscopy was performed using a two-step process, first with a Goldmann 2-mirror lens, followed by indentation gonioscopy using a Sussman lens in selected eyes. The association between a potential risk factor and the presence of AC was initially evaluated using logistic regression models to determine the odds ratios and 95% confidence intervals, adjusting for age and sex. The authors then constructed multiple regression models to assess the independent effects of the various risk factors that were statistically significant after adjusting for age and sex. Of the 2,042 phakic patients that were included in the study, 52.6% were women, 89.4% were Chinese and 19.3% had AC by gonioscopy. After adjusting for age and sex, subjects with AC were more likely to be of Chinese descent, hyperopic, have lower body mass index, shorter axial lengths, shallower anterior chamber depth and higher IOP than subjects without AC. In multivariate analysis, female sex, Chinese ethnicity, axial length and central anterior chamber depth of less than 2.80 mm were independently associated with AC. This is not the first time that a large-scale epidemiological evaluation of AC has been undertaken, but it remains an important study to help better understand the characteristics and prevalence of AC. The authors cite previous studies and note that their study found a higher prevalence of AC than others. They explain their higher prevalence based on their definition of AC as 180 degrees of posterior pigmented TM not visible, compared to 270 degrees in another large scale study. Additionally, they note that their subjects were without a history of glaucoma, laser iridotomy or ophthalmic complaints and were recruited from general physicians, making a selection bias less likely. Limitations of the study were cited by the authors: lens thickness was not measured and that the ciliary body was not imaged by ultrasound biomicroscopy. These tests would have provided more information about the pathophysiology of AC in this population. There were few non-Chinese subjects and it was a community-based study of older adults from physician offices rather than a population-based study. While the results of the study cannot be extrapolated to an entire population, they can still be applied when characterizing the independent predictors of AC.

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