Histopathology of episcleral fibrosis after trabeculectomy with and without mitomycin C

Background: The aim of the study was to investigate the histopathologic features of scar tissue which have proliferated at the site of trabeculectomy of surgical failures after procedures with and without the use of the anti-metabolite mitomycin C (MMC). Methods: Wt obtained seven surgical specimens after trabeculectomy without MMC and five specimens after trabeculectomy with MMC, which were compared with 23 controls. Sections were stained with hematoxylin and eosin, Verhoeff-van Gieson, Grocott methenamine silver, and alcian blue. An immunohistochemical stain was performed for alpha-smooth muscle actin. Results: Specimens from eyes operated without MMC showed dense scar tissue with many fibroblasts, much ground substance, parallel-oriented collagen fibers, and contractile intracellular proteins within the Fibroblasts. Specimens from eyes operated with MMC consisted of tissue with only few fibroblasts which did not exhibit contractile proteins. Collagen fibers were arranged randomly with less ground substance, Conclusion: Even after 1-10 months, the scar tissue was distinctly different in the two groups. These results suggest that the use of MMC has long-term effects in vivo, Surgical failures related to scar formation are possible and not reduced to zero.