Objectives: An index approach for measuring the reduction in daily activities of patients suffering from an eye disease associated with progressive visual loss is proposed. The approach is illustrated using data collected from patients with cataract.

Method: The approach uses recently developed methods based on index theory together with measurements of daily activities. In a simulation based on observations of visual acuity and daily activities in patients with cataract, indexes of changes in benefits were estimated for varying levels of visual acuity.

Results: Results show the development of loss in benefits resulting from a progressive deterioration in visual acuity. The results indicate a 40% loss in benefits at low levels of visual acuity, equivalent to a potential increase in benefits of 75% for these individuals following successful treatment.

Conclusions: The proposed index approach may prove useful for measuring reductions in daily activities resulting from the progressive loss of vision in eye disease. The approach has successfully measured the reduction in daily activities in patients with cataract and may be applicable in patients with other eye diseases, including age-related macular degeneration and open-angle glaucoma.