title: The prevalence of astigmatism and its determinants in a rural population of Iran: the "Nooravaran Salamat" mobile eye clinic experience.
abstract: OBJECTIVE
  The prevalence of astigmatism, and the astigmatic axis, and their determinants were evaluated in a rural population of Iran.
  
  
  METHODS
  In a cross-sectional study conducted from May to August 2011, 13 villages in the vicinity of the city of Khaf in northeast Iran were investigated in this study. All the examinations including visual acuity, refraction, slit-lamp biomicroscopy and fundoscopy were performed in a Mobile Eye Clinic. Written informed consent was obtained from all participants. Only phakic eye that could be reliably refracted without a previous history of ocular surgery were included.
  
  
  RESULTS
  Out of 2635 participants who were screened, 2124 were analysed for this study of whom 52% were female. The prevalence of astigmatism was 32.2% (95% confidence intervals (CI): 30.2-34.2). Astigmatism significantly increased from 14.3% in the under 15-year-old age group to 67.2% in the age group of over 65-years old (P < 0.001). The prevalence of With-The-Rule (WTR), Against-The-Rule (ATR), and oblique astigmatism was 11.7%, 18.1%, and 2.4 %, respectively. ATR significantly increased with age (P < 0.001). The mean corneal astigmatism was 0.73 D which linearly increased with age (P < 0.001).
  
  
  CONCLUSIONS
  Attention must be paid to astigmatism in rural areas due to the high prevalence. Further studies are suggested to discover the role of the environmental and genetic factors. It seems that environmental and occupational factors in the villages cause a significant increase in the prevalence of astigmatism with age. A high percentage of participants had ATR astigmatism, which was more common at older ages.
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: Farhad
authors.initials: F
authors.lastname: Rezvan
authors.affiliation: Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran.
authors.forename: Abbas Ali
authors.initials: AA
authors.lastname: Yekta
authors.affiliation: Department of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Hashemi
authors.affiliation: Department of Medicine, Dezful University of Medical Sciences, Dezful, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Norouzirad
authors.affiliation: Department of Epidemiology, Faculty of Public Health, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khabazkhoob
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D008952:Mobile Health Units / Q000706:statistics & numerical data*; D015995:Prevalence; D012029:Refraction, Ocular; D012424:Rural Population / Q000706:statistics & numerical data*; D017678:Sex Distribution; D014787:Vision Tests; D014792:Visual Acuity; D055815:Young Adult
keywords: Astigmatism; Iran; Prevalence; Rural