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Purpose: To quantify and localize plasmid transfection of filtration surgery tissues using two delivery techniques., Methods: Full-thickness filtering procedures were performed on eyes of New Zealand albino rabbits. In 10 eyes, naked plasmid DNA in saline was either injected beneath Tenon's capsule at the filtration site or absorbed into a collagen shield that was then placed external to the sclerostomy and under the Tenon's capsule. Forty-eight hours after surgery, levels of the reporter gene, chloramphenicol acetyltransferase (CAT) were measured in samples of ocular tissues. In two additional eyes, the ss-galactosidase (ss-GAL:) reporter gene expression was localized histologically., Results: Injection of plasmid DNA in saline vehicle into the filtration bleb produced readily detectable CAT activity in bleb tissue (conjunctiva, Tenon's capsule, and sclera) whereas CAT activity was nearly undetectable in samples of the cornea, iris-ciliary body, and tissues located opposite the bleb site. Delivery of the plasmid DNA into the bleb through a collagen shield increased CAT activity 30-fold over injection of plasmid in saline (2711 +/- 567 mU/mg versus 92 +/- 38 mU/mg). ss-Gal activity was imaged only in the region of the bleb, and microscopic examination showed ss-Gal activity localized to Tenon's capsule fibroblasts, with minimal ss-Gal activity observed in inflammatory cells or scleral fibroblasts., Conclusions: Transfection of filtration tissues is enhanced by absorption of naked DNA into a collagen shield. Furthermore, transfection is localized to the fibroblasts and inflammatory cells of the filtration bleb site. Gene therapy using naked plasmid DNA and a simple collagen shield delivery vehicle may be useful for regulating wound healing after glaucoma surgery.

Purpose: The mechanism through which peribleb injection of autologous blood results in resolution of bleb leak in the rabbit model remains unclear. This study evaluates the clinical and histologic effects of peribleb injection of transforming growth factor-beta (TGF-beta) after leak induction in mitomycin-C-treated blebs., Method: Posterior lip sclerectomies treated with mitomycin-C were created in New Zealand White rabbits. On postoperative day 7, a standardized stab incision was performed on all blebs, and the eyes were randomized to receive a peribleb injection of either TGF-beta or of a balanced salt solution., Results: Injection of TGF-beta was associated with the resolution of bleb leak and maintenance of a functioning bleb in 50% (4 of 8) of treated eyes. The remaining TGF-beta-treated eyes and control eyes demonstrated continued bleb leaks or bleb failures with intraocular pressure returning to preoperative levels. Histologic examination revealed increased peribleb cellularity and denser collagen deposition in the TGF-beta-treated eyes compared with that observed in control eyes., Conclusions: Peribleb TGF-beta injections may contribute to healing bleb leaks, but the injections do not appear in this model to be as useful as whole-blood injections.

Purpose: Bleb leaks after trabeculectomy with antimetabolites can be recalcitrant to therapy. Peribleb autologous blood injections are a moderately successful new treatment modality for such leaks. However, it is unclear what mechanism the injections work to achieve leak resolution., Methods: A randomized, prospective study in the rabbit model was undertaken to evaluate further the clinical and histologic effects of peribleb autologous blood injection after leak induction in mitomycin-C exposed blebs, compared to controls that received only peribleb balanced salt solution injections., Results: In the blood-treated eyes, all bleb leaks healed. Control eyes either demonstrated persistent bleb leaks with shallow anterior chambers or failed blebs that were Seidel negative. Histologic results were remarkable for increased peribleb cellularity and collagen deposition in the blood-treated eyes, compared to controls., Conclusions: Peribleb autologous blood injections are associated with bleb leak resolution, increased peribleb cellularity, and collagen deposition in the rabbit model.

Background: Managing filtration surgery bleb leaks can be difficult as well as frustrating. Treatment options traditionally have included aqueous suppressants, patching, and bleb compression devices. Previously, if conservative management failed, surgical revision was considered., Methods: Six patients with thin avascular blebs and discrete leaking holes (2 had had full-thickness procedures, 4 had had trabeculectomy with mitomycin C) underwent subconjunctival injection of approximately 1 ml of whole autologous blood. Injections were made just lateral and just medial to the domed cystic elevation of the blebs., Results: Five of six eyes were leak-free by the second day after the procedure. No complications occurred. After 4 to 12 months of follow-up, four eyes are currently leak-free. In these eyes, intraocular pressure is between 8 and 12 mmHg., Conclusion: Subconjunctival peribleb injection of autologous blood may be a safe and helpful adjunct in treating selected postfiltration surgery bleb leaks.