title: An enhanced functional ability questionnaire (faVIQ) to measure the impact of rehabilitation services on the visually impaired.
abstract: OBJECTIVE
  To develop a short, enhanced functional ability Quality of Vision (faVIQ) instrument based on previous questionnaires employing comprehensive modern statistical techniques to ensure the use of an appropriate response scale, items and scoring of the visual related difficulties experienced by patients with visual impairment.
  
  
  METHODS
  Items in current quality-of-life questionnaires for the visually impaired were refined by a multi-professional group and visually impaired focus groups. The resulting 76 items were completed by 293 visually impaired patients with stable vision on two occasions separated by a month. The faVIQ scores of 75 patients with no ocular pathology were compared to 75 age and gender matched patients with visual impairment.
  
  
  RESULTS
  Rasch analysis reduced the faVIQ items to 27. Correlation to standard visual metrics was moderate (r=0.32-0.46) and to the NEI-VFQ was 0.48. The faVIQ was able to clearly discriminate between age and gender matched populations with no ocular pathology and visual impairment with an index of 0.983 and 95% sensitivity and 95% specificity using a cut off of 29.
  
  
  CONCLUSIONS
  The faVIQ allows sensitive assessment of quality-of-life in the visually impaired and should support studies which evaluate the effectiveness of low vision rehabilitation services.
authors.affiliation: Aston University, Life and Health Sciences, Ophthalmic Research Group, Birmingham, B4 7ET, UK.
authors.forename: James Stuart
authors.initials: JS
authors.lastname: Wolffsohn
authors.affiliation: Australian College of Optometry, Melbourne 3053, Australia ; Royal Victoria Hospital, Belfast BT12 6BA, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Jackson
authors.affiliation: Aston University, Life and Health Sciences, Ophthalmic Research Group, Birmingham, B4 7ET, UK.
authors.forename: Olivia Anne
authors.initials: OA
authors.lastname: Hunt
authors.affiliation: Oxford Eye Hospital, Oxford OX3 9DU, UK.
authors.forename: Charles
authors.initials: C
authors.lastname: Cottriall
authors.affiliation: Royal Victoria Hospital, Belfast BT12 6BA, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Lindsay
authors.affiliation: Altnagelvin Area Hospital, Londonderry BT47 6SB, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Gilmour
authors.affiliation: Low Vision Clinic, Fife Low Vision Centre for the Blind, Fife KY2 5EF, UK.
authors.forename: Anne
authors.initials: A
authors.lastname: Sinclair
authors.affiliation: Manchester Royal Eye Hospital and Manchester Academic and Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Greater Manchester M13 9WL, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Harper
keywords: functional ability; low vision; quality of life; sensitivity; specificity; visual impairment