title: Age-specific Incidence and Prevalence of Keratoconus: A Nationwide Registration Study.
abstract: OBJECTIVE
  To determine the age-specific incidence and prevalence of keratoconus in the modern era of diagnostics.
  
  
  METHODS
  Epidemiologic study.
  
  
  METHODS
  Total of 4.4 million patients from a mandatory health insurance database.
  
  
  METHODS
  Data were extracted from the largest health insurance provider in the Netherlands. Patients aged 10-40 years were defined as the relevant age category for newly diagnosed keratoconus and the annual incidence of newly diagnosed keratoconus was determined. The prevalence of keratoconus was estimated based on the annual incidence, mean age at diagnosis, and average life expectancy. Main outcome measure was the annual incidence and prevalence of keratoconus.
  
  
  RESULTS
  The annual incidence of keratoconus was 1:7500 in the relevant age category (13.3 cases per 100 000, 95% confidence interval [CI]: 11.6-15.2) and the estimated prevalence of keratoconus in the general population was 1:375 (265 cases per 100 000, 95% CI: 260-270). These values are 5-fold to 10-fold higher than previously reported values in population studies. The mean age at diagnosis was 28.3 years and 60.6% of diagnosed patients were male.
  
  
  CONCLUSIONS
  Both the annual incidence and the prevalence of keratoconus were 5-fold to 10-fold higher than previously reported.
authors.affiliation: Utrecht Cornea Research Group, Department of Ophthalmology, University Medical Center Utrecht, Utrecht, Netherlands. Electronic address: d.a.godefrooij@umcutrecht.nl.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Godefrooij
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands; National Institute for Public Health and the Environment, Bilthoven, Netherlands.
authors.forename: G Ardine
authors.initials: GA
authors.lastname: de Wit
authors.affiliation: Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands.
authors.forename: Cuno S
authors.initials: CS
authors.lastname: Uiterwaal
authors.affiliation: Utrecht Cornea Research Group, Department of Ophthalmology, University Medical Center Utrecht, Utrecht, Netherlands.
authors.forename: Saskia M
authors.initials: SM
authors.lastname: Imhof
authors.affiliation: Utrecht Cornea Research Group, Department of Ophthalmology, University Medical Center Utrecht, Utrecht, Netherlands.
authors.forename: Robert P L
authors.initials: RP
authors.lastname: Wisse
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D016001:Confidence Intervals; D003315:Cornea / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D015994:Incidence; D007640:Keratoconus / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012042:Registries; D017678:Sex Distribution; D055815:Young Adult