title: A population-based study of corneal arcus and its risk factors in Iran.
abstract: OBJECTIVE
  To determine the prevalence of corneal arcus, its risk factors, and its relationship to ocular and visual indices.
  
  
  METHODS
  In this cross-sectional study, 300 clusters were randomly selected from Shahroud in the north of Iran, using multistage sampling. A total of 20 people were invited to participate from each cluster. After enrollment, all optometric, biometric and ophthalmic exams were conducted on site.
  
  
  RESULTS
  Of 6311 people invited, 5190 (82.2%) participated in the study. The prevalence of corneal arcus was 23.3% (95% confidence interval, CI, 22.1-24.6), and 98.4% were bilateral cases. The prevalence of corneal arcus was higher in men (odds ratio, OR, 2.02, 95% CI 1.8-2.3, p < 0.001) and increased with age (OR 1.1/year, p < 0.001). In a multivariable-adjusted regression model, age (OR 1.1/year, p = 0.006), male sex (OR 1.30, p = 0.001), diabetes (OR 0.7, p < 0.001), smoking (OR 1.5, p = 0.003), outdoor activity (OR 1.4, p = 0.006), systolic blood pressure (OR 1.01, p = 0.012), and diastolic blood pressure (OR 0.99, p = 0.016) were significantly correlated with corneal arcus. Including biometric components in another model, corneal thickness (OR 0.99, p < 0.001), anterior chamber depth (OR 0.68, p < 0.001) and corneal radius of curvature (OR 1.59, p < 0.001) were significantly correlated with corneal arcus.
  
  
  CONCLUSIONS
  This study adds valuable information to the epidemiology of corneal arcus in Iran and the Middle East. In people aged over 60 years, nearly 50% of the study population had corneal arcus. Older age, male sex, smoking, and systolic hypertension were risk factors for corneal arcus. Corneal arcus was also associated with thin and flat corneas and shallow anterior chamber depth.
authors.affiliation: Noor Ophthalmology Research Center, Noor Eye Hospital , Tehran , Iran .
authors.forename: Hassan
authors.initials: H
authors.lastname: Hashemi
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khabazkhoob
authors.forename: Mohammad Hassan
authors.initials: MH
authors.lastname: Emamian
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shariati
authors.forename: Akbar
authors.initials: A
authors.lastname: Fotouhi
mesh_terms: D000328:Adult; D017677:Age Distribution; D000375:Aging / Q000502:physiology; D001112:Arcus Senilis / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D001699:Biometry; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution; D012737:Sex Factors; D014792:Visual Acuity / Q000502:physiology
keywords: Corneal arcus; Iran; Middle East; cross-sectional study; prevalence; risk factors