title: Additional psychometric information and vision-specific questionnaires are available for age-related macular degeneration.
abstract: OBJECTIVE
  To present psychometric information and studies dealing with questionnaires for age-related macular degeneration (AMD) and visually impaired patients in addition to the study by Finger et al. "Quality of life in AMD: a review of available vision-specific psychometric tools". We propose that their literature search should not have focused solely on the specific eye disease AMD.
  
  
  METHODS
  The literature search was partly replicated (PubMed) by using "visual impairment" instead of "macular degeneration" as free text words. Psychometric information was obtained from the additional studies. Preliminary results from a differential item functioning (DIF) analysis used to examine the relationship between item responses on the Vision-related quality of life Core Measure (VCM1) of AMD patients versus patients with other eye conditions are discussed.
  
  
  RESULTS
  Eight studies of visually impaired patient populations, including AMD patients, are discussed, with psychometric information from six vision-specific questionnaires. The VCM1 items did not present DIF, which means that the items were equally interpreted by all patients.
  
  
  CONCLUSIONS
  The results on DIF and the additional studies presented here confirm that a specific eye disorder is of minor importance in the choice of a vision-specific questionnaire or, in this case, a literature search.
authors.affiliation: Department of Ophthalmology, EMGO Institute, VU University Medical Center Amsterdam, PO Box 7057, 1007 MB, Amsterdam, The Netherlands. r.vannispen@vumc.nl
authors.forename: Ruth M A
authors.initials: RM
authors.lastname: van Nispen
authors.forename: Michiel R
authors.initials: MR
authors.lastname: de Boer
authors.forename: Ger H M B
authors.initials: GH
authors.lastname: van Rens
mesh_terms: D006801:Humans; D008268:Macular Degeneration; D011594:Psychometrics; D011788:Quality of Life; D012106:Research; D011795:Surveys and Questionnaires / Q000592:standards*