Histologic Study after 5-Fluorouracil Injection into the Bleb in Ahmed Valve Implanted Rabbit Eyes

ABSTRACT

PURPOSE: To study the effect of the 5-fluorouracil (5-FU) injection into the bleb after the Ahmed glaucoma valve implant in rabbits. METHODS: Ahmed valve was implanted in normal 10 rabbits without previous ophthalmic history. In 4 of 10 rabbits, 5-FU (50 mg/ml, 0.1ml) was injected into filtering bleb in every two weeks for two times at postoperative 1 month and others were followed up as a control group. We obtained histological findings in 2 rabbis of control group at postoperative 1 month. In the control group and 5-FU injected 4 rabbit eyes, each 2 rabbit eyes were enucleated at postoperative 3 months and 6 months in both groups. The dissected bleb was examined through light microscopy with hematoxyline and eosin (H and E) stain and Masson-Trichrome (M-T) stain, and electron microscopy. RESULTS: The bleb was relatively avascular on gross and histological examination in the 5-FU injected group, and collagen fibers of the 5-FU injected group were less compact than that of the control group at postopeative 3 months. The number of inflammatory cells, fibroblasts and capillaris in outer layer was decreased in the 5-FU injected group. Under the electron microscopic examination, the density of collagen fibers was decreased and the space among them was widened. This change was more prominent in the 5-FU injected group. CONCLUSIONS: We found that the histological changes of blebs were made by the influx of aqueous humor through the Ahmed glaucoma valve and more stimulated by injection of 5-FU into the bleb after implantation of Ahmed glaucoma valve in a rabbit model.