Aims: To evaluate the 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 in Nakuru district, Kenya.
Methods: The WHO/PBD VF20 was pilot tested and modified. 196 cases visually impaired from cataract and 128 population-based controls without visually impairing cataract were identified through a district-wide survey and case finding. Vision- and health-related quality of life were assessed using the WHO/PBD VF20 scale and Euroqol generic health index (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 health and well-being implications of cataract, beyond visual acuity alone.
- Health related quality of life
- Vision related quality of life