Abstract
Abstract: :
Purpose:Although the rat is well established as a model of both general and ocular wound healing, the standard animal model for the investigation of wound healing following glaucoma filtration surgery (GFS) has been the rabbit. Newer investigative tools that examine changes at a genetic level, have made investigation of the rat desirable. This aim of this study was to create a functioning model of GFS in the rat. Methods:1) GFS was performed on 20 adult Sprague–Dawley rats by introducing a 30–gauge silicone cannula into the anterior chamber (AC) through a penetrating scleral tunnel, under a limbal–based conjunctival flap and suturing the conjunctiva closed. 2) Identical GFS was performed on 3 additional rats, which were sacrificed for histological evaluation at days 2, 5 and 10 respectively, following surgery. 3) Simple fistulising surgery was also performed on 6 Sprague–Dawley rats, for comparison, by creating a needle, full–thickness sclerostomy under a limbal–based conjunctival flap and suturing the conjunctiva closed. Results:Following surgery, the IOP was evaluated daily with a Tonopen, the length and width of the bleb was measured at a slit–lamp and AC depth assessed. Filtering "blebs" formed at the site of the cannula GFS immediately and were observed to be elevated and avascular for 24–48 hours following surgery, becoming less elevated and more vascularised in appearance by day 4–5 and had failed completed by day 8–13. Histological evaluation of sections from the additional rats, confirmed that the filtering tubes extended from the AC into the sub–conjunctival space. Simple fistulising surgery failed by 2–3 days following surgery. Conclusions:Conjunctival wound healing in the mouse following the sub–conjunctival injection of Physiologically Balanced Saline and scleral (needle) fistulising surgery have been previously described. To our knowledge this is the first rat model of GFS, which, like the rabbit model developed by Khaw et al parallels human drainage implant procedures. This creates a surgical wound healing model which not only drains aqueous into the sub–conjunctival space but additionally is long–standing enough to characterize progressive bleb failure. Funded in part by an unrestricted departmental grant from Research to Prevent Blindness