Abstract
Purpose::
To construct a model of relationships among perceived visual function, quality of life (QOL), and visual acuity (VA) using the structural equation modeling (SEM) technique in an older visually impaired population of India.
Methods::
The World Health Organization QOL questionnaire adopted as a health-related QOL (HRQOL) questionnaire (Nutheti R et al, IOVS. 2006; 47: 4742-8) and a 16-item visual function questionnaire (VFQ) (Nutheti R et al, IOVS. 2004; 45:3458-3465) were administered to adults in the population-based Andhra Pradesh Eye Disease Study prior to their visual acuity assessment. A total of 1333 (97.9% of the eligible 1362) visually impaired subjects (presenting VA < 6/18) aged ≥ 40 years responded to both questionnaires. The direct and indirect relationships between VA, VFQ, and QOL scores were established using the SEM after adjusting for socio-demographic and systemic morbidity variables.
Results::
The mean age was 60.5 years ± 9.8 (SD) range from 40 to 102 years; 753 (56%) were female; and 1133 (85%) resided in rural areas. The mean VA, QOL, and VFQ scores were 0.84 ± 0.33 (logMAR), 73.7 ± 20.6, and 74.7 ± 15.8, respectively. For every one logMAR unit (10 lines) worsening in the VA, there was a 29.1% decrease in the perceived visual function and 18.4% decrease in the quality of life score. A total of 62.2% of the change in quality of life was due to the indirect association between VA and QOL through functional vision. The remaining 38.8% change was due to the independent association between VA and QOL. The fit of the hypothesized model (i.e., VA is directly and indirectly through visual function associated with QOL) was acceptable (Comparative Fit Index = 0.995). The percentage of the change in quality of life due to the mediating effect of visual function between VA and QOL varied for different age groups (50%, ≥ 70 years; to 100%, 40 - 49 years), area of residence (59.7%, rural; 100%, urban), sex (56.2%, male; 67.2%, female), and level of visual impairment (61.5%, blind; 100%, moderately visually impaired).
Conclusions::
Perceived visual ability to perform the functional vision activities mediates the relationship between visual acuity and quality of life.
Keywords: quality of life • perception • computational modeling