INTRODUCTION The refractive surface of the cornea is responsible for more than two-thirds of the optical power of the eye. Visual performance can be significantly affected when corneal shape or regularity is subjected to change. Corneal curvature changes induced following vitrectomy and scleral buckling are well-known surgery complications that may cause reductions in visual acuity (1, 2) . In recent years, transconjunctival sutureless vitrectomy (TSV) has been adopted as the preferred

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... for vitreoretinal surgery. The advantages of sutureless small-gauge vitrectomy include techni cal simplicity, less traumatic conjunctival and scleral manipulation, shorter operative durations, less severe postoperative pain, and faster postoperative visual recovery (2, 3) . Several studies have demonstrated corneal changes induced by standard 20-G vitrectomy; however, few studies have investigated ABSTRACT Purpose: To evaluate and compare corneal topographic changes following pars plana vitrectomy with the 23-gauge (G) and 25-G transconjuntival sutureless vitrectomy system as well as the standard 20-G vitrectomy system. Methods: We prospectively evaluated corneal topographic changes in 45 eyes of 45 patients divided into three groups according to vitrectomy system used (20-, 23-, and 25-G). All patients underwent computer-assisted videokeratography using an EyeSys System 3000 topographer preoperatively and at one week, one month, and three months postoperatively. Results: In the 20-G vitrectomy group, we found statistically significant postoperative changes in corneal curvature parameters with an average steepening of 0.98 ± 0.18 D (P<0.001) and 0.93 ± 0.21 D (P<0.001) at one week and one month, respectively. No statistically significant difference was observed at the three-month follow-up visit. In the 23-and 25-G groups, no statistically significant changes in corneal curvature parameters were observed at any postoperative follow-up visit. Conclusion: Twenty-three-gauge and 25-gauge transconjunctival sutureless vitrectomy did not induce topographic corneal changes following surgery, whereas 20-G vitrectomy was found to induce transient topographic corneal changes that had returned to preoperative levels at three months postoperatively. Um estudo comparativo das alterações topográficas da cornea após a vitrectomia via pars plana com 20, 23 e 25 gauge