title: The development of the Indian vision function questionnaire: field testing and psychometric evaluation.
abstract: OBJECTIVE
  To develop and evaluate the acceptability, reliability, validity, and responsiveness of the Indian vision function questionnaire (IND-VFQ).
  
  
  METHODS
  Problem statements from previous qualitative studies were reduced to a 45 item interviewer administered questionnaire representing three a priori domains (general functioning, psychosocial impact, and visual symptoms) which was evaluated in patients with cataract (n = 420), glaucoma (n = 120), diabetic retinopathy, or age related macular degeneration (n = 120) and normal controls (n = 120). Standard methods were used for item reduction and to evaluate psychometric properties.
  
  
  RESULTS
  Psychometric item reduction produced a 33 item questionnaire. Psychometric evaluation showed that two of the three scales (psychosocial impact and visual symptoms) had good acceptability, and that all three scales showed high internal consistency (alpha >0.80; item-total correlations 0.54-0.86) and test-retest reliability (>0.89). All three scales showed moderate evidence of convergent and discriminant validity. Responsiveness, assessed in cataract patients (n = 120) before and after surgery, was good for all three scales (effect sizes >1).
  
  
  CONCLUSIONS
  The IND-VFQ33 is a psychometrically sound measure of vision function addressing a gap in patient defined measures of vision function developed in populations living in low income countries.
authors.affiliation: Dr Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: S K
authors.initials: SK
authors.lastname: Gupta
authors.forename: K
authors.initials: K
authors.lastname: Viswanath
authors.forename: R D
authors.initials: RD
authors.lastname: Thulasiraj
authors.forename: G V S
authors.initials: GV
authors.lastname: Murthy
authors.forename: D L
authors.initials: DL
authors.lastname: Lamping
authors.forename: S C
authors.initials: SC
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Donoghue
authors.forename: A E
authors.initials: AE
authors.lastname: Fletcher
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D002386:Cataract / Q000150:complications; D003906:Developing Countries; D005260:Female; D005901:Glaucoma / Q000150:complications; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D011594:Psychometrics; D011788:Quality of Life; D015203:Reproducibility of Results; D012164:Retinal Diseases / Q000150:complications; D011795:Surveys and Questionnaires; D014786:Vision Disorders / Q000209:etiology / Q000523:psychology / Q000534:rehabilitation*