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Rongxuan Lim, Andreas Karydis, Simon Taylor; A scleral tunnel graft-free technique in Ahmed glaucoma valve (AGV) implantation. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5617.
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© ARVO (1962-2015); The Authors (2016-present)
Erosion of glaucoma drainage device tubes through the conjunctiva can lead to serious complications such as endophthalmitis. The use of pericardium or scleral patch grafts to cover the tube is most often used to reduce this risk. Compared to using a patch graft, the scleral tunnel technique is less costly and also does not have the theoretical infection risk that use of a patch graft is associated with. We performed a retrospective observational clinical study on the outcomes of AGVs implanted via a partial thickness scleral tunnel, without using any patch grafts.
All patients who had AGV implanted using a partial thickness scleral tunnel technique in a single hospital from 2011-2015 were identified from the operating theatre logbook. The clinical notes of these patients were recalled for analysis of baseline characteristics and surgical outcomes, including the identification of any tube erosions.
18 patients were identified. The mean follow-up was 1.7±1.4 years. The mean age of the patients at surgery was 73.4±9.2 years. The cases include 72% neovascular glaucoma, 11% primary open angle glaucoma, 6% posner schlossman, 6% pseudoexfoliation and 6% uveitic glaucoma. Mean intraocular pressures (IOPs) before AGV implant and at final follow-up were 40.8±11.9mmHg and 15.9±7.9mmHg respectively. Median visual acuity before and after AGV implant were both counting fingers. There was no tube erosion noted, although 2 patients (11%) had end-plate erosion, requiring explantation of the AGV. Other post-operative complications (occurring at any point) include hyphaemas >1mm (33%), choroidal effusions (22%), shallow anterior chamber requiring healon injection (6%), tenon’s cyst requiring excision (6%) and fibrosed bleb requiring needling (6%). All hyphaemas and choroidal effusions resolved without intervention. Success at final follow-up (IOP between 5 and 21mm Hg with least 20% reduction from baseline IOP, without additional glaucoma surgery nor loss of light perception) was 72%.
No tube erosions occurred with this scleral tunnel technique of AGV implantation in our study. 2 patients had end-plate exposure, which is probably unrelated to the scleral tunnel technique itself. This partial thickness scleral tunnel approach to AGV implantation is a viable alternative to using patch grafts in preventing tube erosion through the conjunctiva. Longer follow-up studies are required.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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