Vision impairment and major causes of vision loss impacts on vision-specific functioning independent of socioeconomic factors.

PURPOSE: To quantify the eye disease-specific impact of unilateral and bilateral vision impairment (VI) on vision-specific functioning (VF).
DESIGN: The Singapore Indian Eye population-based study. PARTICIPANTS: Ethnic Indians older than 40 years of age living in Singapore.
METHODS: Participants underwent standardized ophthalmic assessments for VI and blindness, defined using presenting visual acuity (United States definition). Sociodemographic data were recorded using a standardized questionnaire. Rasch analysis was used to validate the Visual Function Index 11 and to determine its psychometric properties. The major causes of VI (i.e., cataract, refractive error, age-related macular degeneration, diabetic retinopathy [DR], and glaucoma) were determined by ophthalmologists on examination. Multivariate linear regression analysis was performed to assess the impact of VI on the overall VF Rasch score. MAIN OUTCOME MEASURES: Vision-specific functioning.
RESULTS: Three thousand three hundred ninety-six persons were analyzed. Participants with VI had a systematic reduction in VF score compared with those with normal vision in both eyes, ranging from -11.2% normal vision in one eye and low vision in the other eye (95% confidence interval [CI], -12.2% to -10.3%; P<0.001), to -12.7% blindness in one eye and normal vision in the other eye (CI, -15.1% to -10.4%; P<0.001), to -19.4% low vision in both eyes (CI, -20.8% to -18.1%; P<0.001), to -52.9% blindness in one eye and low vision in other eye (CI, -55.3% to -50.4%; P<0.001), to -77.2% blindness in both eyes (CI, -82.4% to 72.0%; P<0.001). The impact of VI on VF score varied across different major causes of vision loss, regardless of socioeconomic factors. Vision impairment attributed to cataract in one or both eyes had a significant decrease in VF score by 17.7% and 22.3%, respectively, compared with those with normal vision in both eyes (P<0.001). The impact of unilateral and bilateral VI on VF score was greater in participants with glaucoma (32.2% in unilateral cases and 35.9% in bilateral cases; P<0.001) and DR (29.4% in unilateral cases and 33.3% in bilateral cases; P<0.001).
CONCLUSIONS: Vision impairment and major age-related eye diseases such as cataract, DR, and glaucoma are associated significantly with worse deterioration in VF, regardless of education level, literacy adequacy, or immigration pattern. Glaucoma and DR seemed to have a greater negative impact on VF score compared with cataract. This study highlights the importance of disease-specific interventions in reducing the adverse impact of VI on daily activities.