Foreign Body Reaction in Glaucoma Drainage Implant Surgery

PURPOSE. To investigate the histopathology of the foreign body reaction (FBR) and the effect of aqueous humor on it in glaucoma drainage implant surgery. METHODS. A glaucoma drainage device was implanted into 20 New Zealand white rabbits. We monitored the histopathology of blebs at microscopic levels from 3 days to 8 weeks postoperatively. Hematoxylin and eosin staining, Masson's trichrome staining, anti-actin and alpha-smooth muscle immunofluorescence staining, and antiproliferating cell nuclear antigen immunohistochemistry were performed. To observe effects of aqueous humor on FBR, we designed two implant models. One group received a plate with a tube placed in the anterior chamber (experimental group), whereas the other received the plate cut from the tube (control group). RESULTS. Foreign body giant cells were found along the inner border of blebs, and the innermost layer of blebs demonstrated a densely packed collagenous stratum in both groups. The number of foreign body giant cells was suppressed in the experimental group compared with the control group (P < 0.001). Fibroblast division was more active in the experimental group than that in the control group. Masson's trichrome staining demonstrated that the innermost avascular collagenous layer was much thicker in the experimental group than that in the control group (P = 0.021). The extent of alpha-SMA staining was greater in the experimental group than that in the control group. CONCLUSIONS. In the aqueous humor environment, wound healing around a glaucoma drainage implant revealed a unique FBR with the relatively small number of foreign body giant cells and reinforced fibrotic encapsulation.