title: Prevalence of visual impairment in adults with intellectual disabilities in the Netherlands: cross-sectional study.
abstract: OBJECTIVE
  To obtain the first representative and valid population-based prevalence figures on visual impairment and blindness in adults with intellectual disabilities (ID) and to identify risk groups.
  
  
  METHODS
  
  
  
  METHODS
  Cross-sectional survey. An age-Down's syndrome-stratified random sample of 1,598 persons from a base population of 9,012 adult users of ID services with mild to profound intellectual disabilities was screened. Participants underwent protocollised on-site screening of visual functions. Results were related to degree of ID, occurrence of Down's syndrome (DS) and age.
  
  
  METHODS
  Prevalences of visual impairment and blindness in the study population and in subgroups and weighted prevalences in the total Dutch population using ID services.
  
  
  RESULTS
  Prevalences of visual impairment ranged from 2.2% (95% confidence interval (CI), 0.5-6.4) in young adults with mild ID and no Down's syndrome to 66.7% (95% CI, 41.0-86.7) in older adults with profound ID and Down's syndrome; prevalences of blindness ranged from 0.7% (95% CI, 0.1-4.1) to 38.9% (95% CI, 28.1-50.3). Weighted prevalences of visual impairment and blindness in the total Dutch population of adult users of intellectual disability services are 13.8% (95% CI, 9.3-18.4) and 5.0% (95% CI, 3.8-6.2), respectively. Prior to this study, visual impairment or blindness had remained undiagnosed in 106/261 (40.6%) persons.
  
  
  CONCLUSIONS
  As compared to published figures for the general Dutch population aged 55 years and over (visual impairment 1.4%, blindness 0.5%), prevalences of visual impairment and blindness are higher in all subgroups with intellectual disabilities, including the young and mildly handicapped group. The diagnosis is too often missed. All persons with severe or profound intellectual disabilities, and all older adults with Down's syndrome, should be considered visually impaired until proved otherwise.
authors.affiliation: Department of Ophthalmology, University Medical Centre, Utrecht, The Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: van Splunder
authors.forename: J S
authors.initials: JS
authors.lastname: Stilma
authors.forename: R M D
authors.initials: RM
authors.lastname: Bernsen
authors.forename: H M
authors.initials: HM
authors.lastname: Evenhuis
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000453:epidemiology / Q000209:etiology; D003430:Cross-Sectional Studies; D004314:Down Syndrome / Q000150:complications / Q000453:epidemiology; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000150:complications* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D011569:Psychiatric Status Rating Scales; D014786:Vision Disorders / Q000453:epidemiology / Q000209:etiology*