Glaucoma-Associated Visual Task Performance and Vision-Related Quality of Life in South India.

Objective/Purpose: Performance-based measures may provide an objective assessment of how glaucoma affects daily functioning. We sought to validate a clinically-applicable performance-based measure of visual ability for patients with glaucoma in south India and to describe its relationship to clinical and patient-reported outcomes. Design: Cross-sectional validation study. Subjects/Participants/Controls: 145 participants with glaucoma were recruited at Aravind Eye Hospital. Methods/Intervention/Testing: We modified the compressed assessment of activities related to vision (CAARV), a performance-based measure validated in the U.S., to be culturally relevant in south India. Participants underwent a series of tests, including the Indian CAARV (I-CAARV), Indian Visual Functioning Questionnaire (IND-VFQ), Spaeth/Richman Contrast Sensitivity (SPARCS) test, standard automated perimetry, and visual acuity (VA). Factor analysis and Rasch modeling were used to validate the I-CAARV. Correlations between the I-CAARV and other outcomes were evaluated. Main Outcome Measure: Psychometric properties of the I-CAARV for individuals with glaucoma in south India. Results: The study included 142 participants (51.7% female, mean age 56.4 years). Average presenting visual acuity and visual field mean deviation (MD) in the better-seeing eye were 0.26 logMAR and -6.57 dB, respectively. The four tasks of the I-CAARV were found to measure a single underlying construct. Rasch analysis of the I-CAARV revealed that the outcome measure had moderate reliability, good construct and content validity, and fair measurement precision. Tasks were well-targeted to the study sample. Rasch-calibrated scores on the I-CAARV were significantly correlated with Rasch-calibrated IND-VFQ scores (r=-0.54) and with visual field MD, presenting VA, best-corrected VA, and SPARCS contrast sensitivity in both the better-seeing eye (r=0.60, -0.51, -0.53, 0.76, respectively) and worse-seeing eye (r=0.48, -0.61, -0.46, 0.69, respectively). Conclusions: The I-CAARV is a valid performance-based measure of vision-dependent functioning in glaucoma in south India. This study also found that I-CAARV task performance was strongly correlated with contrast sensitivity and suggests that performance-based and patient-reported outcomes are related but distinct measures of the impact of glaucoma on functioning and vision-related quality of life. Future studies are needed to determine the sensitivity of the I-CAARV to detect changes due to disease progression that are relevant to functioning and vision-related quality of life.