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Título

VALY (VISUAL ADJUSTED LIFE YEARS): IS IT AN EFFICIENT WAY TO MEASURE SOCIAL IMPACT BASED ON VISUAL INTERVENTIONS?

Introdução

Many non-profit eyecare providers claim that visual interventions can positively impact social outcomes and therefore contribute to the social development goals of the United Nations. Although, there is no standard metric regarding the social impact that follows from these interventions. We created a formula to evaluate how these outcomes on visual improvement can be measured and compared: VALY (Visual Adjusted Life Years).

Métodos

This research involves creating an experimental model to develop a mathematical framework to quantify visual improvement. The VALY calculation is based on three factors: the initial degree of visual impairment, the improvement of vision after the correction, and the expected duration of the intervention (in years). It is calculated for each individual, and the sum of the VALY (Succes Indicator) shows the social impact produced. (Figure 1).

Resultados

The result of the study is the calculation model itself: specific for each pathology, taking into consideration the particularities and the duration of the intervention. The reduction of the degree of disability (DoD) is determined by a table that considers the initial and final visual acuity (VA) of each eye (Figure 2), multiplied by the duration of intervention (in years). For myopia corrected by eyeglasses: initial VA minus final VA, multiplied by the estimated correction time, which is an average of three years (for glasses). An intervention of 100 eyeglasses of 0.5 diopters (DoD of 0.5 D is 10%). Calculation: 100 x 0.1 x 3 years = 30 VALY. An intervention of 50 eyeglasses of 6 diopters (DoD: 100%). Calculation: 50 x 1 x 3 = 150 VALY. For cataract surgery: a patient with initial VA of 20/200 (0.1) to final VA of 20/20 (1.0) (90% improvement), with more than 20 years of life expectancy (at time of surgery); 0.9 x 20 = 18 VALY. Not every intervention has the same weight in the calculation, depending on the level of visual impairment of the individual. A higher VALY corresponds to a higher visual rehabilitation.

Conclusões

VALY can be applied to various interventions, enabling a comparative analysis of their respective impacts on vision improvement over time. The cumulative VALY serves as a crucial and easily reproducible measurement tool, facilitating the evaluation of the effectiveness of visual interventions.

Palavras Chave

Social refraction, Social Impact, social ophthalmology, impact study

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