Graft-free Ahmed tube insertion: a modified method at 5 mm from limbus

Abstract

ObjectiveTo determine the medium-term outcome of Ahmed implants inserted through a needle tract at 5 mm from limbus that eliminates the need for a donor scleral graft.MethodsA retrospective case series of 19 patients undergoing Ahmed implant surgery for refractory glaucoma with a mean follow-up of 12 months. Primary outcome measures included control of intraocular pressure after surgery. Secondary outcome measure included the frequency of intraoperative and postoperative complications.ResultsIntraocular pressure was maintained between 6 and 21 mmHg throughout the study. There was no postoperative hypotony. There were no complications related to this modified technique.ConclusionNeedle tract at 5 mm from limbus maintains implant’s ability to control intraocular pressure and eliminates the need for a donor scleral graft or heterologous material.

Graft-free glaucoma drainage device implantation: Short tunnel small flap technique

“…The idea is that these methods of insertion provide a flatter configuration and less chance of exposure. 7 Attempts to minimize the risk of exposure by changing the position of the tube started by creating a lamellar flap and burying the tube under the flap before inserting into anterior chamber. 10 Since the path was lamellar and not full thickness, tube erosion was still a problem so patch graft became standard of care for coverage of tubes.…”

“…Although the superior half of the tube was unprotected and directly in contact with conjunctiva, no case of erosion has been encountered during 12 months' follow-up. 7 There are two concerns regarding intra-tunnel insertion technique. Since tube follows the contour of the globe, it may be displaced toward the cornea and may cause corneal decompensation.…”

“…Several methods have been proposed to prevent this type of erosion including large scleral flap and sclera tunnel techniques. [6][7][8] While large scleral flap creation is time demanding and difficult in cases of scarring and scleral thinning, intrascleral tunnel technique is faster, simpler and more feasible in cases of conjunctiva insufficiency. However, since surgeons need to follow the contour of the globe to insert the tube in the anterior chamber, it is not uncommon that the tube tip sits very close to the cornea.…”

Ahmed Glaucoma Valve Implantation: Graft-Free Short Tunnel Small Flap versus Scleral Patch Graft After 1 Year Follow-Up: A Randomised Clinical Trial

“…The idea is that these methods of insertion provide a flatter configuration and less chance of exposure. 18 The drawbacks of the scleral flap are the need for extensive conjunctival exposure and cautery as well as free patch graft to prevent tube exposure through partial thickness lamellar flap. 29 Another approach is to pass the tube into a tunnel created by 23 gauge needle.…”

“…[13][14][15] Alternatives to patch graft are either a large scleral flap or scleral tunnel techniques. [16][17][18][19] We proposed a graft-free GDD implantation method that combines advantages of both scleral flap and tunnel techniques while faster, simpler, and with better tube position in the anterior chamber. 12 This study is a randomized clinical trial comparing the safety and efficacy of graft free short tunnel small flap technique and patch graft method in Ahmed glaucoma valve (AGV, New World Medical Inc, Rancho Cucamonga, California, USA) implantation.…”