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 m) and the opposite site (740 +/- 80 mum) (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. (C) 2004 by the American Academy of Ophthalmology.