Ahmed glaucoma valve implantation with hangback technique

Surinder Singh Pandav, Anupam Banger, Sushmita kaushik, Srishti Raj

Advanced eye centre, Post Graduate Institute of Medical Education and Research Centre, Chandigarh.

Aim: To report results of Ahmed Glaucoma Valve (AGV) implantation in eyes with high risk of surgical failure, using a modified technique where plate of the AGV is not sutured to sclera (Hang Back Technique).

Materials and Methods: 88 eyes of 79 patients of refractory glaucoma in the age group of 3 to 75 years who underwent AGV implantation with or without concomitant procedures from January 2007 to December 2009 were studied. Of these, 31 eyes (39.2%) had undergone filtering surgery earlier whereas remaining eyes underwent primary AGV implantation following failure of maximal medical therapy. The minimum follow up of the patients was 6 months. All AGV implants was performed by a single surgeon.

The AGV plate was placed in the sub-Tenon's space in the supero-temporal quadrant between two adjacent recti muscles. The plate was not sutured to the sclera and was allowed to 'hang' from the tube which was anchored to the sclera near its insertion in to the anterior chamber. Anterior part of the tube was covered with a human donor sclera patch graft. The conjunctiva with Tenon's capsule was sutured to the limbus, and all eyes received subconjunctival of dexamethasone and antibiotic injection at the end of the procedure. Postoperatively, all patients received topical steroid, antibiotic and cycloplegic eye drops. Patients were followed up at day 1, day 7, 2 weeks, 4 weeks, 3 months, and 6 monthly thereafter.

Results: There were 23 females and 56 males in the study. The mean age was 41.56 ±20.821 years with range: 3years – 75 years of age.The mean (SD) IOP decreased from a preoperative value of 34.57mmHg (10.21mmHg) to 9.19mmHg (6.71mmHg) at one week, 15.90 mmHg (9.251mmHg) at one month, 17.13mm Hg (6.42mm Hg) at three months and 15.89mm Hg (6.95mm Hg) at 6months. Bilateral AGV implantation was done in 9 patients. The visual acuity remained stable in most of the eyes. The average number of glaucoma medications decreased from 2.92 ±0.80 medications to 1.15 ±0.88. Most common complications were shallow anterior chamber in 14 eyes (17.3%), hyphema 11 eyes (11.9%) , other complications include choroidal detachment and tube retraction. In 77% eyes the the procedure was considered successful. Fifteen eyes underwent additional procedure such as cataract surgery or vitrectomy with AGV implantation.

Conclusion: The AGV implantation with unsutured plate is safe and effective in controlling IOP in cases of adult refractory glaucoma. This technique has the advantage of being easy, involves less dissection and eliminates the risk of sclera perforation during suturing of valve plate to sclera.