title: Refractive errors in a rural Korean adult population: the Namil Study.
abstract: OBJECTIVE
  To assess the prevalence of refractive errors, including myopia, high myopia, hyperopia, astigmatism, and anisometropia, in rural adult Koreans.
  
  
  METHODS
  We identified 2027 residents aged 40 years or older in Namil-myeon, a rural town in central South Korea. Of 1928 eligible residents, 1532 subjects (79.5%) participated. Each subject underwent screening examinations including autorefractometry, corneal curvature measurement, and best-corrected visual acuity.
  
  
  RESULTS
  Data from 1215 phakic right eyes were analyzed. The prevalence of myopia (spherical equivalent (SE) <-0.5 diopters (D)) was 20.5% (95% confidence interval (CI): 18.2-22.8%), of high myopia (SE <-6.0 D) was 1.0% (95% CI: 0.4-1.5%), of hyperopia (SE>+0.5 D) was 41.8% (95% CI: 38.9-44.4%), of astigmatism (cylinder <-0.5 D) was 63.7% (95% CI: 61.0-66.4%), and of anisometropia (difference in SE between eyes >1.0 D) was 13.8% (95% CI: 11.9-15.8%). Myopia prevalence decreased with age and tended to transition into hyperopia with age up to 60-69 years. In subjects older than this, the trend in SE refractive errors reversed with age. The prevalence of astigmatism and anisometropia increased consistently with age. The refractive status was not significantly different between males and females.
  
  
  CONCLUSIONS
  The prevalence of myopia and hyperopia in rural adult Koreans was similar to that of rural Chinese. The prevalence of high myopia was lower in this Korean sample than in other East Asian populations, and astigmatism was the most frequently occurring refractive error.
authors.affiliation: Department of Ophthalmology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Y C
authors.initials: YC
authors.lastname: Yoo
authors.affiliation: Department of Ophthalmology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: J M
authors.initials: JM
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: K H
authors.initials: KH
authors.lastname: Park
authors.affiliation: Department of Ophthalmology, Severence Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: C Y
authors.initials: CY
authors.lastname: Kim
authors.affiliation: Department of Ophthalmology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
authors.forename: T-W
authors.initials: TW
authors.lastname: Kim
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D015858:Anisometropia / Q000453:epidemiology*; D001251:Astigmatism / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000453:epidemiology*; D015995:Prevalence; D056910:Republic of Korea / Q000453:epidemiology; D012424:Rural Population / Q000706:statistics & numerical data*; D017678:Sex Distribution; D014792:Visual Acuity / Q000502:physiology
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