Cataract visual impairment and quality of life in a Kenyan population

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.