Assessment of vision-related quality of life in an older population subsample: The Blue Mountains Eye Study

Purpose: To assess visual functioning and vision-specific health-related quality of life (HRQOL) in an older, community-dwelling-based population subsample, using the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25). Methods: Three-quarters (76%, n = 892) of Extension Blue Mountains Eye Study participants ( aged >= 50 years, mean 60.8 years) completed the self-administered NEI-VFQ-25, an instrument consisting of 12 dimensions and one summary composite score, and comprehensive eye examinations, including monocular distance visual acuity. Visual impairment was defined as visual acuity < 6/12. Unilateral and bilateral visual impairment was defined by the worse eye and better eye, respectively. Correctable visual impairment was defined as that which improved, and non-correctable visual impairment as that which persisted after subjective refraction. Mild visual impairment was defined as visual acuity < 6/12 but >= 6/24, moderate as < 6/ 24 but >= 6/60, and severe as < 6/60. Results: There were no significant differences in age, sex, or vision status between NEI-VFQ-25 responders and non-responders. Men had significantly better scores in three subscales than women but there were no significant differences in their overall composite scores ( men 88.5 +/- 0.5; women 88.1 +/- 0.4). Persons aged 60 - 69 years had the best NEI-VFQ-25 profiles ( mean composite score +/- standard error, 90.2 +/- 0.5; 50 - 59 years, 88.5 +/- 0.4; >= 70 years, 86.2 +/- 0.8). Presenting bilateral visual impairment (77.1 +/- 1.4) was associated with significantly poorer functioning than unilateral (87.5 +/- 0.8) or no visual impairment (89.4 +/- 0.3). Increasing levels of impairment were associated with poorer levels of visual functioning. The impact of impairment was principally from non-correctable (49.2 +/- 2.6) rather than refractive impairments (85.3 +/- 1.4), although the latter accounted for over three-quarters (77.5%) of presenting bilateral impairment. Non-correctable unilateral impairment ( 85.3 +/- 1.1) was associated with poorer functioning than no impairment. Conclusions: The findings from this community-dwelling older population show that the NEI-VFQ25 differentiates well between various levels of visual impairment with regard to the magnitude of their impact on vision-specific quality of life. Greater impacts were noted among persons with bilateral compared to unilateral impairment, with increasing impacts at greater severities of visual impairment. Visual impairment from refractive errors is more frequent than from underlying pathologic disorders, but the impact of correctable visual impairment was considerably milder than the impact of non-correctable visual impairment.