The impact of pterygium excision on corneal astigmatism.

OBJECTIVE To compare the corneal astigmatism before and after the excision of pterygium and also to determine the correlation of pterygium size with the postoperative corneal astigmatism. STUDY DESIGN Cross-sectional interventional study. PLACE AND DURATION OF STUDY Eye Department, Combined Military Hospital, Abbottabad, from May 2011 to March 2012. METHODOLOGY Thirty patients underwent pterygium excision. Pre-operatively Snellen visual acuity, manifest refraction and slit lamp examination was done. The size of the pterygium was recorded in mm by projecting a horizontal slit lamp beam from the limbus to the apex. All the pterygium were equal to or greater than 2.5 mm. Keratometry was performed with an automated keratometer. Keratometric data was recorded pre-operatively and at 28 days postoperatively. Wilcoxon signed rank test was used for comparing the pre-operative and the postoperative corneal astigmatism. Spearman's rank order was calculated to observe correlation of pterygium size with the postoperative astigmatism. RESULTS The median (mean rank) pre-operative astigmatism of 2.25 (15.50) reduced to a median (mean rank) postoperative astigmatism of 1.30 (14.96). This decrease in the postoperative astigmatism was statistically significant (p < 0.001). There was a statistically non-significant correlation between the postoperative astigmatism and the pterygium size (rs = -0.29, p = 0.12). CONCLUSION Pterygium excision caused significant reduction in corneal astigmatism.