title: The prevalence of keratoconus in a young population in Mashhad, Iran.
abstract: OBJECTIVE
  To determine the prevalence of keratoconus and some associated factors in the students of Mashhad University of Medical Sciences, Iran.
  
  
  METHODS
  In this cross sectional study, multistage cluster sampling was used to select the participants. All participants underwent retinoscopy, slit lamp examination, topography with the TMS-4 and corneal assessment with the Orbscan II. The diagnosis of keratoconus was based on both clinical evidence and the results of corneal imaging.
  
  
  RESULTS
  Of 1280 selected students, 1073 agreed to participate in the study, and of those who agreed, 1027 fulfilled the inclusion criteria. 42.5% of the study population was male with a mean age of 26.1 ± 2.3 years. The prevalence of keratoconus was 2.5% (n = 26) (95% confidence interval, CI 1.6-3.5). Eighteen students (69%) had bilateral keratoconus. Imaging of the cornea revealed that 70% of the keratoconics had nipple cones and the remaining had asymmetric bow-tie patterns. The prevalence of keratoconus was not significantly associated with age or gender (p > 0.05). In a multiple logistic regression model, family history (OR = 11.4, 95% CI: 2.5-51.3) and eye rubbing (OR = 6.3, 95% CI: 1.6-24.3) were significantly correlated with keratoconus.
  
  
  CONCLUSIONS
  These results taken together with recent studies in the area suggest that keratoconus may have a higher prevalence in the Middle East and Asia than in Western Countries.
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: Negareh
authors.initials: N
authors.lastname: Yazdani
authors.forename: Hadi
authors.initials: H
authors.lastname: Ostadimoghaddam
authors.forename: Reza
authors.initials: R
authors.lastname: Norouzirad
authors.forename: Kazem
authors.initials: K
authors.lastname: Amanzadeh
authors.forename: Mohammad
authors.initials: M
authors.lastname: Miraftab
authors.forename: Akbar
authors.initials: A
authors.lastname: Derakhshan
authors.forename: AbbasAli
authors.initials: A
authors.lastname: Yekta
mesh_terms: D000328:Adult; D000367:Age Factors; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D007640:Keratoconus / Q000453:epidemiology*; D016015:Logistic Models; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D012737:Sex Factors; D055815:Young Adult
keywords: Middle East; keratoconus; prevalence; risk factors