Corneal refractive changes after trabeculectomy

Purpose: Trabeculectomy can alter corneal curvature during the postoperative course since the surgery involves the limbus and anterior sclera. The aim of this study is to assess refractive changes occuring in the cornea after trabeculectomy surgery.Materials and Methods: Forty-one eyes of 37 patients were inculuded in the study. Eight eyes of patients who have not attended examinations or in whom sufficient quality images could not be obtained were excluded from the study. Twelve eye of eleven patients the whom were operated as trabeculectomy combined with deep sclerectomyprosedures excluded from the study. Hence the study was completed with 21 eyes of 18 patients. Keratometric and topographic mesaurements were obtained and recorded preoperatively and at 1. week, 1., 3. and 6. moths postoperatively. Taking these mesaurements into account, preoperative and postoperative absolute astigmatism values, induced astigmatism values and with the wound components of astigmatism were determined. Vector analysis was performed utilizing Eğrilmez?s ?Vector Analysis Program for the Analysis of Astigmatism? Findings: Absolute astigmatism during the preoperative period, 1. week, 1., 3. and 6. months were determined as 0.86±0.85, 1.33±1.18, 0.88±0.63, 0.79±0.59 and, 0.77±0.58 D., in order. During these same periods topographical absolute astigmatism was found as 0.92±0.59, 2.29±2.36, 1.39±1.30, 1.17±0.80 and 0.82±0.54 D., respectively. Induced astigmatism determined with the keratometer was 1.52±1.80, 1.19±1.15, 1.08±1.13 and 1.12±1.12 D at 1. week, 1.,3. and 6. months. Topographically these valus were 2.23±2.44, 1.60±1.24, 1.40±1.03 and 1.17±0.79 D, in order. With the wound type astigmatism occured in 75% of eyes with topography, and 56% of eyes with keratometer.Conclusions: Trabeculectomy surgery leads to with the wound type astigmatism during the early postoperative period, most conspiciously at 1.week. This induced astigmatism induced by the surgery probably decreases with the loosening of the sutures, and becomes similar to preoperative astigmatism towards the 6. month. These astigmatic changes occur more evident with topographyKey words: Astigmatism, keratometer, trabeculectomy, topography