Cataract visual impairment and quality of life in a Kenyan population
- 1London School of Hygiene & Tropical Medicine, London, UK
- 2Rift Valley Provincial General Hospital, Nakuru Town, Nakuru, Kenya
- Correspondence to: S Polack London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK;
- Accepted 19 January 2007
- Published Online First 1 February 2007
Aims: 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 ⩾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.
Conclusion: 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.
- EQ-5D, European Quality of Life Questionnaire
- EuroQol, European quality of life
- HRQOL, health-related quality of life
- INDVFQ33, Indian VF33 questionnaire
- PCA, principal components analysis
- QOL, quality of life
- SES, socioeconomic status
- VA, visual acuity
- VAS, visual analogue scale
- VF, vision function
- VRQOL, vision-related quality of life
- WHO/PBD VFQ20, World Health Organization Prevention of Blindness and Deafness 20-item Visual Functioning Questionnaire
Published Online First 31 January 2007
Funding: This study was funded by grants from Sight Savers International, Christian Blind Mission and ORBIS International.
Competing interests: None.