Impact of Pterygium Surgery on Corneal Topography

Objective: To evaluate the quantitative and qualitative effects of pterygium surgery on corneal topography. Material and Methods: Eighteen eyes of 17 patients with pterygium were included in the study. Computerized corneal topography were performed preoperatively, at one week-and one month-postoperatively. The quantitative parameters reviewed included central corneal power (sim K), corneal cylinder, surface regularity index (SRI), surface asymmetry index (SAI), horizontal length of the pterygium, surgically induced astigmatism (SIA), and positive astigmatic axis. Topography maps were also evaluated qualitatively. Results: The mean preoperative Sim K was statistically less than the mean Sim K at one week- (p=0.014) and one month- postoperatively (p=0.016). The mean SAT at one week-postoperatively was statistically higher than it was at one month-postoperatively (p=0.017). The mean SRI at one week- postoperatively was higher than it was at one month- postoperatively (p=0.006). Although there was a tendency towards decrease in corneal cylinder after surgery, this decrease was not statistically significant (p=0.833). The horizontal length of the pterygium was positively correlated with the preoperative corneal cylinder, SIA at one week-, and SIA at one month- postoperatively (r=0.741 p=0.000; r=0.771 p=0.000, r=0.669 p=0.002, respectively). Preoperative corneal cylinder was positively correlated with SIA at one week- and one month- postoperatively (r=0.937 p=0.000, r=0.966 p=0.000, respectively). Corneal topography most frequently revealed regular astigmatic patterns before and after surgery. The distribution of spherical, regular astigmatic and irregular astigmatic patterns did not change by surgery (p=0.949). Conclusion: Pterygium causes reversible changes on corneal topography in accordance with its horizontal length.