Abstract
Abstract: :
Purpose:To evaluate the histological changes of posterior bleb on experimental model of Ahmed valve implanted rabbit Methods:Normal 12 rabbits weigh from 1.5kg to 2.5kg were experimented. Ahmed glaucoma valve (Model AGV–S1, New World Medical Co. USA) was implanted aseptically on every rabbit. In 4 of 12 rabbits (group A), the tube of valve was not inserted into the anterior chamber. In another 4 rabbits, tube was inserted into the anterior chamber (group B). In last 4 rabbits, same method as group B was performed but partial ligation with 5–0 prolene was done around the tube over the sclera. After 4 weeks, tube ligation was removed (group C). At postoperative 16 weeks, rabbits of all groups were enucleated and posterior blebs were dissected to see histologic findings and examined by electron microscopy and light microscopy after hematoxyline and eosin (H&E), collagen stain, immunohistochemical (IHC) stain. Results:In group A, bleb had distinct inner wall and outer wall, and was surrounded with lamellar structure composed of proliferating collagen fibers by light microscopy. Inner wall was composed of relatively regular collagen fibers and had more fibroblast than inflammatory cell or vascular tissue. At IHC stain, strong positive staining areas of the myofibroblasts were observed in outer wall of bleb. Collagen fiber bundles were well developed around fibroblasts and no interfibrillar space was seen by electron microscopy. In group B, bleb had splitted collagen fibers and microcysts. Outer wall of bleb had less fibroblasts and capillaries than group A. At IHC stain, splitted and fine collagen fibers and microcysts well developed in the inner wall and weak positive staining areas of the myofibroblast were observed in outer wall of bleb. In group C, bleb had less separated and splitted collagen fibers of inner wall than group A. Outer wall were distinct from inner wall and had relatively irregular loose collagen fibers and more inflammatory cells and vascular structure than fibroblasts. At IHC stain, moderate positive staining areas of the myofibroblast were observed in outer wall of bleb. Conclusions:We found the histological changes of posterior bleb on Ahmed valve implanted eyes as aqueous humor influxes into the bleb. This study shows that aqueous humor inhibits cell proliferation, especially fibroblast, and contribute to a microcystic change of collagen fibers.
Keywords: aqueous • pathology: experimental • wound healing