title: The effect of different criteria on the number of patients blind from open-angle glaucoma.
abstract: BACKGROUND
  The prevalence of blindness and visual impairment from glaucoma is influenced by the criteria used to define these entities, which differ between countries and regions, as well as among published reports. The objective of the present study was to ascertain the extent to which different criteria of blindness and visual impairment influence estimates of the number of patients classified as blind or visually impaired by glaucoma in a clinic-based population.
  
  
  METHODS
  We conducted a retrospective chart review of 914 patients with open-angle glaucoma to compare numbers of patients identified as visually impaired with and without considering visual field status. We also compared proportions classified using World Health Organisation (WHO) and United States (US) blindness criteria, and applying a new US Social Security Administration (SSA) disability criterion: perimetric mean deviation (MD) ≤ -22 dB.
  
  
  RESULTS
  Forty patients (4.4%) were bilaterally blind from glaucoma by the WHO criteria. Fifty-two (5.7%) were blind by the the US criterion. Assessing only visual acuity, 14 (1.5%) patients were blind by the WHO criteria and 24 (2.6%) by the US definition. Eighty-five (9.3%) met the US SSA disability criterion. Among those, 52 were impaired also by the WHO definition. No patients impaired according to the WHO criteria had MD values better than -22 dB.
  
  
  CONCLUSIONS
  Excluding visual field status will seriously underestimate the prevalence of glaucoma blindness. In our patient population, 30% more patients were classified as blind by the US than by the WHO definition. Also, 60% more were identified as visually impaired by the US SSA criterion than by the WHO criteria. Visual field assessment is vital to determine visual impairment caused by glaucoma.
authors.affiliation: Department of Clinical Sciences in Malmö, Ophthalmology, Lund University, Malmö, Sweden. anders.heijl@med.lu.se
authors.forename: Anders
authors.initials: A
authors.lastname: Heijl
authors.forename: Johan
authors.initials: J
authors.lastname: Aspberg
authors.forename: Boel
authors.initials: B
authors.lastname: Bengtsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D004185:Disability Evaluation; D005260:Female; D005902:Glaucoma, Open-Angle / Q000150:complications* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012684:Sensory Thresholds / Q000502:physiology; D014481:United States / Q000453:epidemiology; D015354:Vision, Low / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D014792:Visual Acuity / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014944:World Health Organization
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