title: Myopia in asian subjects with primary angle closure: implications for glaucoma trends in East Asia.
abstract: OBJECTIVE
  To evaluate the occurrence of myopia in Asian subjects with angle closure and to assess the ocular biometric parameters in these subjects.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  We prospectively recruited 427 angle-closure subjects (143 primary angle-closure suspects, 75 patients with primary angle closure, 165 patients with primary angle-closure glaucoma, and 44 patients with acute primary angle closure) from a Singapore hospital.
  
  
  METHODS
  Refractive status was derived from the spherical equivalent of autorefraction. A-scan biometry (Nidek Echoscan Ultrasound US-800; Nidek Co., Tokyo, Japan) was performed to obtain anterior chamber depth (ACD), axial length (AL), lens thickness, and vitreous cavity length (VL). Anterior segment optical coherence tomography was performed to measure lens vault.
  
  
  METHODS
  Refractive status was categorized as myopia (≤-0.50 diopter [D]), emmetropia (-0.50 to +0.50 D), and hyperopia (≥+0.50 D).
  
  
  RESULTS
  The mean age ± standard deviation of study subjects was 65.6 ± 7.6 years, with most being Chinese (n = 394; 92.3%) and women (n = 275; 64.4%). Overall, myopia was present in 94 subjects (22%), hyperopia was present in 222 subjects (52%), and emmetropia was present in 111 subjects (26%). Of the 94 myopic angle-closure patients, 28 (29.8%) were categorized as having moderate myopia (≤-2.0 to -5.0 D) and 11 (11.7%) were categorized as having high myopia (≤-5.00 D). Although myopic angle-closure subjects had longer ALs (P<0.001) and VLs (P = 0.001) than their emmetropic and hyperopic counterparts, there were no significant differences in ACD (P = 0.77), lens thickness (P = 0.44), or lens vault (P = 0.053).
  
  
  CONCLUSIONS
  Almost one quarter of angle-closure patients were myopic. Myopic angle-closure subjects had longer VLs and ALs, but there was no difference in ACD. With the increasing rate of myopia in many East Asian populations, there may be many subjects with axial myopia but shallow ACD and angle closure. The implication is that ophthalmologists should not assume that glaucoma patients who are myopic have open angles.
authors.affiliation: Singapore National Eye Centre and Singapore Eye Research Institute, Singapore, Republic of Singapore.
authors.forename: Kai-Ling
authors.initials: KL
authors.lastname: Yong
authors.affiliation: Bioinformatics Institute, A*STAR (Agency for Science, Technology and Research), Singapore, Republic of Singapore.
authors.forename: Tianxia
authors.initials: T
authors.lastname: Gong
authors.affiliation: Singapore National Eye Centre and Singapore Eye Research Institute, Singapore, Republic of Singapore; Duke-NUS Graduate Medical School, Singapore, Republic of Singapore.
authors.forename: Monisha E
authors.initials: ME
authors.lastname: Nongpiur
authors.affiliation: Singapore National Eye Centre and Singapore Eye Research Institute, Singapore, Republic of Singapore.
authors.forename: Alicia C
authors.initials: AC
authors.lastname: How
authors.affiliation: Bioinformatics Institute, A*STAR (Agency for Science, Technology and Research), Singapore, Republic of Singapore.
authors.forename: Hwee Kuan
authors.initials: HK
authors.lastname: Lee
authors.affiliation: Bioinformatics Institute, A*STAR (Agency for Science, Technology and Research), Singapore, Republic of Singapore.
authors.forename: Li
authors.initials: L
authors.lastname: Cheng
authors.affiliation: Singapore National Eye Centre and Singapore Eye Research Institute, Singapore, Republic of Singapore.
authors.forename: Shamira A
authors.initials: SA
authors.lastname: Perera
authors.affiliation: Singapore National Eye Centre and Singapore Eye Research Institute, Singapore, Republic of Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore. Electronic address: aung.tin@snec.com.sg.
authors.forename: Tin
authors.initials: T
authors.lastname: Aung
mesh_terms: D000328:Adult; D000368:Aged; D000867:Anterior Chamber / Q000473:pathology; D044466:Asian People / Q000208:ethnology; D058452:Axial Length, Eye / Q000473:pathology; D001699:Biometry; D003430:Cross-Sectional Studies; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D007429:Intraocular Pressure; D007908:Lens, Crystalline / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000175:diagnosis / Q000453:epidemiology*; D011446:Prospective Studies; D012846:Singapore / Q000453:epidemiology; D041623:Tomography, Optical Coherence; D014822:Vitreous Body / Q000473:pathology