Surgically induced corneal refractive change following glaucoma surgery: nonpenetrating trabecular surgeries versus trabeculectomy.

PURPOSE To compare surgically induced corneal refractive change following trabeculectomy with the nonpenetrating trabecular filtering surgeries with and without implant. SETTING Department of Ophthalmology, Ege University School of Medicine, Izmir, Turkey. METHODS A consecutive series of 34 patients (34 eyes) with uncontrolled open-angle glaucoma had trabecular filtering surgery. Patients were assigned randomly to receive viscocanalostomy (12 patients), nonpenetrating deep sclerectomy (NPDS) with T-flux implant (10 patients), and trabeculectomy (12 patients). Autokeratometry and computerized corneal videokeratoscopy with the Topcon KR-7000P autokeratorefractometer were performed preoperatively and 1 day and 1, 3, and 6 months postoperatively to analyze surgically induced keratometric and topographic astigmatism. RESULTS Thirty patients (11 trabeculectomy, 11 viscocanalostomy, and 8 NPDS with nonabsorbable implant) completed the study. Mean patient age was 61.7 years +/- 10.9 (SD) (range 37 to 81) and did not differ among groups. Postoperative intraocular pressure (IOP) levels and visual acuity (logMAR values) did not differ among groups compared with preoperative levels. Average induced astigmatism was lower in the NPDS group than the trabeculectomy group at postoperative month 3 and 6 based on autokeratometry values (P =.023 and.042, respectively). Nonpenetrating surgeries resulted in less induced astigmatism in the early postoperative period and less against-the-rule shift over 6 months. CONCLUSION Despite larger flap size and surgical area, nonpenetrating trabecular surgeries induced less astigmatism than trabeculectomy.