The Prevalence and Types of Glaucoma in an Urban Chinese Population

IMPORTANCE: Glaucoma represents a major public health challenge in an aging population. The Tanjong Pagar Eye Study reported the prevalence and risk factors of glaucoma in a Singapore Chinese population in 1997, which established the higher rates of blindness in this population. OBJECTIVES: To determine the prevalence and associated risk factors for glaucoma among Chinese adults in Singapore and to compare the results with those of the 1997 study. DESIGN, SETTING, AND PARTICIPANTS: In a population-based survey of 4605 eligible individuals, we selected 3353 Chinese adults 40 years or older from the southwestern part of Singapore. Participants underwent examination at a single tertiary care research institute from February 9, 2009, through December 19, 2011. EXPOSURES: All participants underwent slitlamp ophthalmic examination, applanation tonometry, measurement of central corneal thickness, gonioscopy, and a dilated fundus examination. MAIN OUTCOMES AND MEASURES: Glaucoma as defined by the International Society of Geographical and Epidemiological Ophthalmology guidelines and age-standardized prevalence estimates computed as per the 2010 Singapore Chinese census. Blindness was defined as logMAR visual acuity of 1.00 (Snellen equivalent, 20/200 or worse). RESULTS: Of the 3353 respondents, 134 (4.0%) had glaucoma, including primary open-angle glaucoma (POAG) in 57 (1.7%), primary angle-closure glaucoma (PACG) in 49 (1.5%), and secondary glaucoma in 28 (0.8%). The age-standardized prevalence (95% CI) of glaucoma was 3.2% (2.7%-3.9%); POAG, 1.4% (1.1%-1.9%); and PACG, 1.2% (0.9%-1.6%). In a multivariate model, POAG was associated with being older and male and having a higher intraocular pressure. Of the 134 participants with glaucoma, 114 (85.1%; 95% CI, 78.1%-90.1%) were not aware of their diagnosis. Prevalence (95% CI) of blindness caused by secondary glaucoma was 14.3% (5.7%-31.5%), followed by 10.2% (4.4%-21.8%) for PACG and 8.8% (3.8%-18.9%) for POAG. We could not identify a difference in the prevalence of glaucoma compared with the 3.2% reported in 1997 (difference, -0.04%; 95% CI, -1.2 to 1.2; P = .97). CONCLUSIONS AND RELEVANCE: The prevalence of glaucoma among Singapore Chinese likely ranges from 2.7% to 3.9%, with secondary glaucoma being the most visually debilitating type. We could not identify a difference compared with previous studies approximately 12 years earlier. We report a high proportion of previously undiagnosed disease, suggesting the need to increase public awareness of this potentially blinding condition.