OBJECTIVE: Measure the benefits of delaying the progression to blindness and compute an overall index that summarizes the benefits to patients treated for eye problems. METHODS: Patients benefits are measured in terms of the reduction in symptoms and disabilities, and in terms of the patient’s ability to perform preferred activities in their daily living. The index is based on earlier work in the field of index theory, distance functions, and production economics. It uses both clinical outcome data and data on specific daily life activities. The index results in a single measure of relative changes in functional ability, for each individual. Daily life activities are treated as outputs that the individual is able to perform. Resources that the individual uses to achieve the outputs are treated as inputs. Hence, treatment may increase the input level of a particular individual and by that increase the output possibility set, and subsequently the individual’s choice between different output combinations. The situation before treatment is compared with the situation after treatment. The index numbers are calculated from the Swedish Cataract Register, and from clinical trial data. Cost data are collected from the literature. RESULTS: The suggested index approach successfully connects multidimensional outcome data with daily life activities, without being dependent on an a priori set of weights or secondary statistical analysis. The index allows different variables to be measured in different units without affecting the resulting index number. The preliminary empirical results indicate that new technology and proper timing of the medical intervention is crucial for the economic justification of the intervention. CONCLUSION: With a minimum of assumptions the suggested index makes it possible to analyze a medical intervention using all of the appropriate variables. The index may prove particular useful in the decision process of medical interventions and when balancing costs and benefits. CARDIOVASCULAR DISEASE –SESSION 2