Subepithelial Fibrosis After RK
Mitomycin-C has been used widely in glaucoma filtering surgery to prevent scar formation and resultant bleb failure and in pterygium excision surgery to prevent recurrence of pterygium. The toxic side effects of MMC include hyperemia, pain, blepharospasm, secondary glaucoma, corneal edema, corneal perforation, iritis, corneoscleral melt and perforation, and photophobia.
In Majmudar and coauthors' case series, a #64 blade was used to remove the corneal epithelium and mechanically remove as much of the fibrosis as possible. A sterile 6.0 mm circular sponge soaked in MMC (0.02%) was applied to the corneal surface for 2 minutes. Care was taken to limit MMC exposure to the central 6.0 mm of the corneal surface. The sponge was then removed, and the ocular surface was irrigated with 30 mL of balanced salt solution (BSS®).
Epithelial plugs and active fibroblasts can exist in corneal wounds for long periods after RK. In our series, the recurrence of the subepithelial fibrosis occurred possibly as a result of wound-site keratocytes activated by the excimer laser ablation. We believe the appropriate surgical management for superficial corneal fibrosis after RK involves manual debridement of the epithelium and manual excision of the fibrotic scar. This was followed by a relatively minimal excimer laser ablation to smooth the corneal surface after removal of the superficial corneal fibrosis. This approach for superficial corneal fibrosis after RK does not include any possibility of toxic side effects from MMC. Currently, there is no randomized study that can completely address the relative safety and efficacy of these 2 procedures.
Yi-Chiang Fong MD
Roy Chuck MD, PhD
Walter Stark MD
Peter McDonnell MD© 2000 by Lippincott Williams & Wilkins, Inc.