MEASUREMENTS OF VISION FUNCTION AND QUALITY-OF-LIFE IN PATIENTS WITH CATARACTS IN SOUTHERN INDIA - REPORT OF INSTRUMENT DEVELOPMENT

Objective: To develop and validate vision function (VF) and quality of life (QOL) instruments inpatients with cataracts in the context of la rge volume surgery in a developing country. Materials and Methods: The instruments were developed using a consensus approach. One hundred pa tients who were undergoing cataract surgery at Aravind Eye Hospital, M adurai, India, were interviewed preoperatively and 3 and 12 months pos toperatively. Standard clinical procedures were followed, including me asurement of visual acuity. Between-interviewer reproducibility was me asured by repeated administration of the preoperative questionnaire. W ithin-interviewer reproducibility was measured preoperatively in a sep arate study of 50 patients. Results: Preoperative scores from the VF a nd QOL instruments were significantly associated with visual acuity (r = 0.4). Internal reliability (Cronbach alpha) was greater than .9. Bo th instruments showed large changes after surgery, with effect sizes o f 3 or greater for most VF scales (range, 1.8-3.7) and 1 or greater fo r QOL scales (range, 1.0-2.2). Changes in visual acuity after surgery were correlated with changes in the VF (r = 0.44) and QOL (r = 0.41) s cale scores. Between interviewer reproducibility was acceptable (total VF scale, Spearman r = 0.7; total QOL scale, r = 0.74). The kappa val ues were lower for within-interviewer reproducibility. Conclusions: Th e study provided strong evidence for the validity, reproducibility, an d responsiveness of the instruments, and for the feasibility of using them in the setting of a large volume of cataract surgery in a develop ing country.