title: Myopia, axial length, and age-related cataract: the Singapore Malay eye study.
abstract: OBJECTIVE
  To describe the associations of myopia and axial length (AL) with age-related cataract in an Asian population in Singapore.
  
  
  METHODS
  A population-based cross-sectional study that examined 3280 (78.7% response) adults of Malay ethnicity aged 40 to 80 years. Refractive error was determined by subjective refraction and AL was measured using the Zeiss IOL-Master. Digital slit lamp and retroillumination lens photographs were taken and graded for age-related nuclear, cortical, and posterior subcapsular (PSC) cataract following the Wisconsin system.
  
  
  RESULTS
  After excluding eyes with prior refractive or cataract surgery, 5474 eyes with gradable lens photographs were analyzed. In multivariate analyses adjusting for age, sex, body mass index, systolic blood pressure, glycosylated hemoglobin, smoking status, and education, myopia (spherical equivalent less than -0.5 diopter [D]) was associated with an increased prevalence of nuclear (OR: 4.99, 95% CI: 3.72–6.69) and PSC cataract (OR: 1.34, 95% CI: 1.30-1.39) but not with cortical cataract (OR: 0.85, 95% CI: 0.68-1.08) compared with emmetropia. Per-millimeter increase in AL was not associated with any of the three cataract subtypes. When myopia was defined as spherical equivalent of less than -5.0 D to -6.0 D, the OR of myopia for PSC cataract increased dramatically.
  
  
  CONCLUSIONS
  Our study shows that myopia, but not AL, was associated with nuclear cataract, supporting the concept of index myopia with aging. Myopia, especially high myopia, may predispose to PSC cataract formation. Clinically, ophthalmologists should be aware that risk of PSC cataract appears to vary by refractive status.
authors.affiliation: Singapore Eye Research Institute, Singapore.
authors.forename: Chen-Wei
authors.initials: CW
authors.lastname: Pan
authors.forename: Pui Yi
authors.initials: PY
authors.lastname: Boey
authors.forename: Ching-Yu
authors.initials: CY
authors.lastname: Cheng
authors.forename: Seang-Mei
authors.initials: SM
authors.lastname: Saw
authors.forename: Wan Ting
authors.initials: WT
authors.lastname: Tay
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Ava Grace
authors.initials: AG
authors.lastname: Tan
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000208:ethnology; D058452:Axial Length, Eye; D002386:Cataract / Q000453:epidemiology* / Q000208:ethnology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009216:Myopia / Q000453:epidemiology* / Q000208:ethnology; D015995:Prevalence; D012846:Singapore / Q000453:epidemiology
keywords: axial length; cataract risk factors; myopia