VISUAL FUNCTION FOLLOWING TRABECULECTOMY - EFFECT ON CORNEAL TOPOGRAPHY AND CONTRAST SENSITIVITY

Purpose: This study was to determine the role of changes in refractive error, contrast sensitivity, and corneal topography in transient chan ges in visual function following trabeculectomy. Methods: We performed a prospective study evaluating these factors in 13 consecutive patien ts undergoing a standardized trabeculectomy. Preoperatively, and at 1, 4, and 12 weeks postoperatively, we measured best-corrected visual ac uity, refractive error, and contrast sensitivity and analyzed computer ized video-keratographic studies including estimated corneal visual ac uity. Results: One week postoperatively, best-corrected visual acuity decreased at least one line in 8 of 13 patients, whereas no eyes had d ecreased contrast sensitivity. Mean central corneal astigmatism increa sed 1.4 diopters along the surgical meridian. By 12 weeks, visual acui ty returned to preoperative levels in all patients and the corneal top ographic changes returned to within 1 diopter of preoperative values i n 12 of 13 patients. Postoperative changes in estimated corneal visual acuity were similar to those in best-corrected visual acuity with no statistically significant difference. Conclusions: Corneal topographic changes appear to contribute to visual acuity reduction following tra beculectomy. In most cases this is transient with return to preoperati ve topography within 12 weeks.