title: Cataract visual impairment and quality of life in a Kenyan population.
abstract: OBJECTIVE
  To evaluate the World Health Organization Prevention of Blindness and Deafness 20-item Visual Functioning Questionnaire (WHO/PBD VF20), a vision-related quality of life scale, and to describe the relationship between cataract visual impairment and vision- and generic health-related quality of life, in people >or=50 years of age in Nakuru district, Kenya.
  
  
  METHODS
  The WHO/PBD VF20 was pilot tested and modified. 196 patients with visual impairment from cataract and 128 population-based controls without visual impairment from cataract were identified through a district-wide survey. Additional cases were identified through case finding. Vision- and health-related quality of life were assessed using the WHO/PBD VF20 scale and EuroQol generic health index (European Quality of Life Questionnaire (EQ-5D)), respectively. WHO/PBD VF20 was evaluated using standard psychometric tests, including factor analysis to determine item grouping for summary scores.
  
  
  RESULTS
  The modified WHO/PBD VF20 demonstrated good psychometric properties. Two subscales (general functioning and psychosocial) and one overall eyesight-rating item were appropriate for these data. Increased severity of visual impairment in cases was associated with worsening general functioning, psychosocial and overall eyesight scores (p for trend <0.001). Cases were more likely to report problems with EQ-5D descriptive dimensions than controls (p<0.001), and, among cases, increased severity of visual impairment was associated with worsening self-rated health score.
  
  
  CONCLUSIONS
  The modified WHO/PBD VF20 is a valid and reliable scale to assess vision-related quality of life associated with cataract visual impairment in this Kenyan population. The association between health-related quality of life and visual impairment reflects the wider implications of cataract for health and well-being, beyond visual acuity alone.
authors.affiliation: London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK. sarah.polack@lshtm.ac.uk
authors.forename: Sarah
authors.initials: S
authors.lastname: Polack
authors.forename: Hannah
authors.initials: H
authors.lastname: Kuper
authors.forename: Wanjiku
authors.initials: W
authors.lastname: Mathenge
authors.forename: Astrid
authors.initials: A
authors.lastname: Fletcher
authors.forename: Allen
authors.initials: A
authors.lastname: Foster
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002386:Cataract / Q000150:complications* / Q000503:physiopathology / Q000523:psychology / Q000534:rehabilitation; D005260:Female; D006305:Health Status Indicators; D006801:Humans; D007630:Kenya; D008297:Male; D008875:Middle Aged; D011594:Psychometrics; D011788:Quality of Life; D012959:Socioeconomic Factors; D014786:Vision Disorders / Q000209:etiology* / Q000503:physiopathology / Q000523:psychology / Q000534:rehabilitation; D014792:Visual Acuity