title: The frequency of occurrence of certain corneal conditions by age and sex in Iranian adults.
abstract: OBJECTIVE
  To determine the prevalence of posterior embryotoxon, corneal opacity, pigment on endothelium, corneal dystrophy, and corneal vascularization in a middle-aged Iranian population, and their association with age and sex.
  
  
  METHODS
  In a cross-sectional study with multistage cluster sampling, subjects were chosen from 40 to 64-year-old residents of Shahroud in northern Iran. Participants had ophthalmic examinations before and after pupil dilation. Corneal abnormalities were diagnosed by an ophthalmologist using a slit lamp.
  
  
  RESULTS
  Of the 6311 invitees, 5190 people (82.2%) participated; 58.6% (n=3040) were female. The prevalence of posterior embryotoxon, corneal opacity, and pigment on endothelium were 14.7% (95% CI: 13.4-16.0), 4.1% (95% CI: 3.4-4.7) and 1.2% (95% CI: 0.9-1.5), respectively, and corneal dystrophy and corneal vascularization were seen in 0.3% (95% CI: 0.2-0.5) and 3.7% (95% CI: 3.0-4.3), respectively. Unlike posterior embryotoxon, the prevalence of all studied abnormalities increased with age after adjusting for sex. The prevalence of posterior embryotoxon (p=0.023) and corneal dystrophy (p=0.038) was significantly higher in women, and the prevalence of corneal opacity (p<0.001) was significantly higher in men. After adjusting for age, sex, and cataract, cases with corneal opacity and corneal vascularization demonstrated significantly worse uncorrected and corrected visual acuity (p<0.001).
  
  
  CONCLUSIONS
  This report is the first to explore the prevalence of a variety of corneal conditions in a Middle-Eastern population. The findings indicate that one out of five people may have some sort of corneal conditions, and some can impact corrected visual acuity.
authors.affiliation: Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Hashemi
authors.affiliation: Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khabazkhoob
authors.affiliation: Shahroud University of Medical Sciences, Shahroud, Iran.
authors.forename: Mohammad Hassan
authors.initials: MH
authors.lastname: Emamian
authors.affiliation: Department of Community Medicine, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Shariati
authors.affiliation: Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Abbasali
authors.initials: A
authors.lastname: Yekta
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: afotouhi@tums.ac.ir.
authors.forename: Akbar
authors.initials: A
authors.lastname: Fotouhi
mesh_terms: D000328:Adult; D017677:Age Distribution; D003316:Corneal Diseases / Q000453:epidemiology*; D003317:Corneal Dystrophies, Hereditary / Q000453:epidemiology; D016510:Corneal Neovascularization / Q000453:epidemiology; D003318:Corneal Opacity / Q000453:epidemiology; D003430:Cross-Sectional Studies; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010808:Physical Examination; D015995:Prevalence; D017678:Sex Distribution; D066167:Slit Lamp
keywords: Corneal dystrophy; Corneal opacity; Corneal vascularization; Cross-sectional study; Pigment on endothelium; Posterior embryotoxon