title: Prevalence, Risk Factors, and Visual Features of Undiagnosed Glaucoma: The Singapore Epidemiology of Eye Diseases Study.
abstract: OBJECTIVE
  Glaucoma can remain asymptomatic until a severe stage, resulting in a high prevalence of undiagnosed glaucoma worldwide. Asia accounts for 60% of the world's total glaucoma cases. To our knowledge, no epidemiological studies have assessed ethnic differences in undiagnosed glaucoma among various Asian subgroups.
  
  
  OBJECTIVE
  To determine the prevalence of, risk factors for, and visual features of undiagnosed primary glaucoma in a multiethnic Asian population.
  
  
  METHODS
  The Singapore Epidemiology of Eye Diseases Study is a population-based trial in which 3353 Chinese (2009-2011), 3280 Malays (2004-2006), and 3400 Indians (2007-2009) aged 40 to 80 years were invited for an eye examination, including visual field assessment, to establish glaucoma diagnosis. Participants with undiagnosed glaucoma (ie, answering no to whether they previously had been told by a physician that they had glaucoma, not using glaucoma medication, or not having undergone glaucoma surgery) were identified.
  
  
  METHODS
  Prevalence of, risk factors for, and visual features of undiagnosed glaucoma.
  
  
  RESULTS
  Of 272 participants with primary glaucoma, 196 (72.1%) were previously undiagnosed. The overall prevalence of undiagnosed primary glaucoma was highest among Malays (2.65%; 95% CI, 2.10%-3.31%), followed by Chinese (1.51%; 95% CI, 1.13%-2.01%) and Indians (0.97%; 95% CI, 0.64%-1.43%). In multivariable analysis, variables associated with higher risk of undiagnosed glaucoma were younger age (odds ratio [OR], 1.04; 95% CI, 1.00-1.09; P = .04), Malay ethnicity (OR, 3.65; 95% CI, 1.31-10.13; P = .01), presence of primary open-angle glaucoma (OR, 3.82; 95% CI, 1.60-9.14; P = .003), absence of yearly eyeglass checks (OR, 9.29; 95% CI, 3.43-25.21; P < .001), and lack of cataract surgery (OR, 4.19; 95% CI, 1.68-10.48; P < .001). No patients were blind in both eyes. A mean (SD) of 4.1% (2.8%) (n = 8) of the newly diagnosed patients were blind in 1 eye, and a mean (SD) of 56.0% (7.2%) (n = 102) had noteworthy visual field damage (mean deviation worse than -6 dB) in at least 1 eye.
  
  
  CONCLUSIONS
  The prevalence of undiagnosed primary glaucoma varied among ethnic populations in whom a mean (SD) of 49.0% (14.0%) (n = 24) of affected individuals 50 to 59 years old already had clinically significant visual field loss. Such data may assist policymakers in implementing cost-effective public health interventions to reduce the effect of blindness associated with undiagnosed glaucoma.
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Chua
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore2Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore3Duke-National University of Singapor.
authors.forename: Mani
authors.initials: M
authors.lastname: Baskaran
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Peng Guan
authors.initials: PG
authors.lastname: Ong
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Yingfeng
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore2Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore3Duke-National University of Singapor.
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore2Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore.
authors.forename: Tin
authors.initials: T
authors.lastname: Aung
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore2Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore3Duke-National University of Singapor.
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Cheng
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000208:ethnology; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis* / Q000208:ethnology* / Q000503:physiopathology; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology