Comparison of Corneal Higher-order Aberration before and after Excision of Pterygium

ABSTRACT

PURPOSE: To investigate the types of corneal higher-order aberration (HOA) induced by pterygium, residual corneal HOA after pterygium surgery, and correlations between corneal HOA and the length of the pterygium. METHODS: Fifty-three patients who underwent pterygium excision with conjunctival autograft were enrolled. Corneal HOA was measured by Pentacam® (Oculus Inc., Wetzlar, Germany) preoperatively and 3 months postoperatively in the 6-mm optical zone. Preoperative and postoperative HOAs of eyes with pterygium were compared with HOAs of the fellow eye to evaluate HOAs induced by pterygium and residual HOAs after pterygium surgery. Partial correlation analysis was performed to investigate the relationship between HOAs and the length of pterygium. A postoperative HOA less than 0.35 µm in size was defined as a favorable surgical outcome and the surgical indications were estimated using receiver operator characteristic (ROC) curve. RESULTS: Horizontal coma, root mean square (RMS) of coma, oblique trefoil, horizontal trefoil, RMS of trefoil, and total HOA were significantly greater in the eye with preoperative pterygium. Three months after pterygium excision, only RMS of coma and total HOA remained significantly greater in eyes with pterygium. Vertical coma, horizontal coma, RMS of coma, and oblique tetrafoil were correlated with pterygium length. Pterygium excision when pterygium length was less than 1.6 mm led to favorable surgical outcomes. CONCLUSION: Pterygium induced greater than third-order corneal HOAs and these HOAs were corrected via pterygium surgery. Longer pterygium length was associated with larger RMS of coma and larger coma RMS persisted after pterygium surgery. A pterygium length of 1.6 mm should be considered the cutoff for pterygium excision for reducing postoperative corneal HOA.