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 in patients with cataracts in the context of large volume surgery in a developing country.

MATERIALS AND METHODS

The instruments were developed using a consensus approach. One hundred patients who were undergoing cataract surgery at Aravind Eye Hospital, Madurai, India, were interviewed preoperatively and 3 and 12 months postoperatively. Standard clinical procedures were followed, including measurement of visual acuity. Between-interviewer reproducibility was measured by repeated administration of the preoperative questionnaire. Within-interviewer reproducibility was measured preoperatively in a separate study of 50 patients.

RESULTS

Preoperative scores from the VF and QOL instruments were significantly associated with visual acuity (r = 0.4). Internal reliability (Cronbach alpha) was greater than .9. Both instruments showed large changes after surgery, with effect sizes of 3 or greater for most VF scales (range, 1.8-3.7) and 1 or greater for 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) scale scores. Between-interviewer reproducibility was acceptable (total VF scale, Spearman r = 0.7; total QOL scale; r = 0.74). The kappa values were lower for within-interviewer reproducibility.

CONCLUSIONS

The study provided strong evidence for the validity, reproducibility, and responsiveness of the instruments, and for the feasibility of using them in the setting of a large volume of cataract surgery in a developing country.