Histology of conjunctival vascular endothelium after filtering surgery with mitomycin C in rabbits.

OBJECTIVE: To examine histologic changes in conjunctival vasculature during the first 72 hours following filtering surgery with adjunctive mitomycin C in rabbits. DESIGN: Thirty-six New Zealand white rabbits underwent unilateral posterior lip sclerectomy. In 18 rabbits mitomycin C (0.5 mg/mL) was applied subconjunctivally for 5 minutes. The remaining 18 animals were treated with the phosphate-buffered saline vehicle for 5 minutes. Three rabbits from either group were killed at 0, 4, 12, 24, 48 and 72 hours postoperatively. OUTCOME MEASURES: Degree of vascularity of filtering blebs on gross examination and appearance of conjunctival vascular specimens on light and transmission electron microscopy, as assessed by three masked observers. RESULTS: On gross examination the filtering blebs in the mitomycin C group were slightly less hyperemic than those in the control group at 12, 24 and 48 hours and were markedly less hyperemic at 72 hours. Light microscopy showed tightly packed erythrocytes within the conjunctival vessels of the experimental blebs and an almost total absence of endothelium within many of the vascular channels by 72 hours. Transmission electron microscopy showed focal loss of vascular endothelial cells and thrombus formation in the experimental blebs, as early as 12 hours postoperatively. CONCLUSIONS: Our findings suggest that the decreased vascularity of filtering blebs observed after trabeculectomy with adjunctive mitomycin C is at least partially due to a toxic effect of the agent on the endothelial cells of the conjunctival vessels.

Duke Scholars

Author John Daniel Shelburne Pathology