Toxic effects of 5-fluorouracil on fibroblasts following trabeculectomy

The inhibitory effect of 5-fluorouracil (5-FU) on fibroblast proliferation is well established. In addition, toxic effects of 5-FU on existing fibroblasts, in rabbits and in vitro, were demonstrated. We examined human subconjunctival scar tissue which was removed during Molteno tube implantation. Surgery was performed 9 weeks after filtering surgery with 5-FU that resulted in bleb scarring. In the tissue, intracytoplasmic vacuoles were detected in some myofibroblasts, with no visible collagen in their vicinity. This presumed toxic effect of 5-FU may be one explanation for the adequacy of fewer than twice 5-FU injections daily following filtering surgery, and for less than 14 days, as originally recommended for inhibiting bleb scarring.