Corneal topographic changes after four types of pterygium surgery

PURPOSE: To evaluate effects of different pterygium surgeries on corneal topography. METHODS: Pre- and postoperative computerized video-keratography was performed on 120 eyes of 115 patients undergoing pterygium removal. Four techniques were used: bare sclera, excision with mitomycin C, limbal-conjunctival autograft, and conjunctival autograft. Corneal spherical power, topographical astigmatism, pre- and postoperative topographic irregularity, and surgically induced astigmatism were compared among surgical approaches. RESULTS: Mean topographic astigmatism value decreased significantly 4 months postoperatively. The difference among the postoperative astigmatism values at 4 months was statistically significant (P<.001). Statistically significant differences were noted between the type of surgery and surgically induced astigmatism (P<.05), mean topographical astigmatism (P<.05), and spherical power (P<.05), but no significant difference was observed in topographic irregularity (P=.067). The amount of corneal steepening in each group was 0.06 +/- 0.5 for conjunctival autograft, 0.02 +/- 0.3 for limbal-conjunctival autograft, 2.34 +/- 1.1 for bare sclera, and 1.70 +/- 0.4 for mitomycin C. The mitomycin C group produced the most induced astigmatism and the limbal-conjunctival autograft group produced the least induced astigmatism. CONCLUSIONS: Although pterygium surgery significantly reduces refractive astigmatism and topographic irregularity, spherical power increases and the cornea becomes steeper. This steepening is apparent with the bare sclera or excision combined with mitomycin C approaches. Surgeons should consider the possibility of recurrence and the effects of different types of surgeries of topography.