This study evaluated the WHO/PBD VF20, an instrument recommended for measuring VRQOL in low‐income settings, in Nakuru district, Kenya. To our knowledge no other studies have explored the association between visual impairment from cataract and quality of life in Kenya.
The results show that the modified WHO/PBD VFQ20, with one overall rating item and two subscales, (general functioning and psychosocial) is a valid and reliable scale in this Kenyan setting. One item about glare from glare from bright lights was removed, but this might have more relevance in other settings. The item about pain in the eye did not correlate well with other items in the scale. Cases reported worse pain scores than controls; however, among the cases, there was no significant variation in pain score with VA. Pain and discomfort are not typical symptoms of cataract, but this item might be more relevant for other ocular morbidities. However, it was not included in the original INDVFQ33 which was developed on the basis of 46 focus group discussions exploring patient's perceptions about their eye conditions and associated impact on daily living.24
There was some redundancy in items, suggesting that it might be possible to shorten this questionnaire further, although the full questionnaire should be evaluated in other settings to confirm this.
Cases were more likely to report problems with the EQ‐5D dimensions than controls. Increasing severity of visual impairment was associated with higher odds of reporting problems with mobility, self‐care, usual activities, and pain/discomfort and with mean self‐rated health score. These findings correspond to studies from high‐income settings,5
and highlight an impact of visual impairment on wider well‐being that is not necessarily reflected by vision related scales.
Sociodemographic and economic variables influenced response independently of VA. This is in accordance with other studies,5,14
and suggests that experiences of visual impairment may vary according to individual circumstances. In a study in Hong Kong, Lau et al25
comment that, despite comparable VA and using the same scale, mean VRQOL scores were better than those in China and Nepal, and suggest that this may be due to differences in modern household utilities which facilitate self‐care activities. A similar reason may explain why cases in the lower SES groups in Nakuru had worse general functioning scores. Promotion of surgical services at early stages of cataract in poor communities should remain a priority. Being widowed/single increased the social and emotional burden of cataract visual impairment, as reflected by poorer psychosocial scores compared with married people. In contrast, but in accordance with findings from the INDVFQ 33 in India,14
there was no association between VRQOL scores and age or sex.
This study has its limitations. Three different case recruitment methods were used. However, all cases were from the same district and met the same case definition. According to power calculations, 133 controls were required for the study, but only 128 were identified. However, the power calculations were based on very conservative estimates, so the effect of this is probably minimal. The WHO/PBD VF20 was recommended as an instrument to assess all ocular morbidities and we focused only on cataract. Further, we focused only on people aged
50 years, and the scale might perform differently in other age groups. However, the original INDVFQ33 was also developed in people aged
50 years, and, although other eye conditions were included, was largely dominated by cataract, reflecting the relative importance of this condition in the Indian setting. Our results indicated that some items in the Kenyan setting were not relevant or were redundant. Future studies should look at the performance of the full WHO/PBD VF20 scale in other populations or other disease groups. The translation of the EQ‐5D questionnaire was not validated by the EuroQol group, although standard translation procedures were followed. Multiple tests of statistical significance for correlated measures were made using these data. However, analyses were repeated using the Bonferroni correction and the multivariate analyses were essentially unchanged.
In this study, evidence of the validity and reliability of a new scale were shown, and the data suggest that this scale would be suitable for assessing the outcome of cataract surgery. The findings add weight to the evidence of disability and poorer self‐perception of own health associated with cataract visual impairment among people in an African country.