Long-term effects of mitomycin C in pterygium surgery on scleral thickness and the conjunctival epithelium.

PURPOSE To evaluate the long-term effects of intraoperative application of mitomycin C on the scleral thickness and the conjunctival epithelium at the surgical site of pterygium excision. DESIGN Prospective observational case series. PARTICIPANTS Twenty-four patients who underwent excision of primary pterygium with intraoperative mitomycin C in our department during the year 1996. METHODS Patients were evaluated by slit-lamp biomicroscopy, impression cytology, and high-frequency ultrasonography. Impression cytology was performed by applying a small nitrocellulose filter paper for a few seconds at the excision area and for a few seconds at the opposite perilimbal area, and subjecting the specimens to the periodic acid-Schiff-Gill modified Papanicolaou staining protocol. The morphology of the conjunctival epithelium and goblet cell density (GCD) were recorded. High-frequency ultrasound was performed at the same sites, and the scleral thickness was measured at a distance of 1 mm from the limbus. MAIN OUTCOME MEASURES Goblet cell density, conjunctival epithelial morphology, and the scleral thickness at the operated and nonoperated sites. RESULTS All patients had successful pterygium removal with no corneal recurrence after a mean follow-up of 77.2+/-3.9 months (range, 72-84). Impression cytology revealed normal nongoblet conjunctival epithelial cells at the excision area, with a 4-fold decrease in the GCD at the excision area when compared with the contralateral nonoperated site (296+/-120 cells/mm(2) and 1183+/-310 cells/mm(2), respectively; P = 0.0036). No differences were noted between the scleral thicknesses at the operated site (750+/-70 microm) and the opposite site (740+/-80 microm) (P = 0.84). CONCLUSIONS A single application of mitomycin C after pterygium excision is not associated with reduction in scleral thickness more than 6 years postoperatively. The conjunctival epithelium retains its normal phenotype, with a marked reduction of the GCD.