A novel surgical technique for prevention of Ahmed glaucoma valve tube exposure: long scleral flap augmented with Tenon advancement and duplication

Abstract

BackgroundTo describe a new technique and present its long-term outcome for prevention of Ahmed glaucoma valve (AGV) tube exposure in patients with refractory glaucoma.MethodsTwenty-seven eyes of 24 patients (mean age, 50 years; age range, 16–78 years; 8 females, 16 males) with refractory glaucoma who had the AGV implant were retrospectively reviewed. For AGV implantation, a long scleral flap combined with Tenon advancement and duplication was used. In this technique, a long scleral flap is created to completely cover the extraocular part of valve’s tube, and the flap surface is covered with duplicated Tenon’s tissue. The average follow-up after AGV implantation was 21.7 months (range, 12–36 months).ResultsThe mean intraocular pressure before the operation, which was 44.1 mmHg (range, 26–62 mmHg), decreased to 14.2 mmHg (range, 8–20 mmHg) at the last follow-up visit, showing 67% reduction with AGV implantation. The mean number of antiglaucomatous medications was 4.1 before the AGV implantation and decreased to 0.9 after the operation, showing 88% reduction. In 14 eyes (51.9%), there was no change in the best corrected visual acuity (BCVA), and in 11 eyes (40.7%), the BCVA increased by 2 lines on the Snellen chart postoperatively. No patient developed postoperative hypotony, flat anterior chamber, diplopia, strabismus, erosion or exposure of the tube, or tube/plate migration.ConclusionsThe long scleral flap augmented with Tenon advancement and duplication is an effective and safe surgical technique for the implantation of AGV and preventing tube exposure in cases of refractory glaucoma.

Five-Year Outcomes of Graft-Free Tube Shunts and Risk Factors for Tube Exposures in Glaucoma

“…The lack of long-term outcomes and small sample sizes were pervasive among retrospective cohort studies without patch grafts (Supplemental Digital Content 2, http://links.lww.com/IJG/A796). The 5 graft-free studies identified had variable surgical techniques, including scleral tunnels and flaps 7–11 . None reached 5 years of follow-up, with only Gdih and Jiang 7 reporting success rate at 1 year, which was lower than ours (87% vs. 91%).…”

“…Supplemental Digital Content 2, http://links.lww.com/IJG/ A796 shows the result of a literature review comparing the current study to others with at least 1 year of follow-up after AGV implantation. 2,3,5,[7][8][9][10][11][12][13][14][15][16] The current study reported numerically higher rates of success at all time points compared with all retrospective cohort studies with patch graft usage except for one 15 (Supplemental Digital Content 2, http://links.lww.com/ IJG/A796). These studies included at maximum 58 eyes, using different types of patch grafts (dura, scleral, and pericardial).…”

“…None reached 5 years of follow-up, with only Gdih and Jiang 7 reporting success rate at 1 year, which was lower than ours (87% vs. 91%). Four of 5 studies had limited sample size (<30 eyes), and all the studies had significantly shorter follow-up (1–3 y), 8–11 . The only study with over 30 eyes (n=84) 7 had a follow-up of 1 year.…”

A graft-free scleral sleeve technique of Ahmed Glaucoma Valve implantation in refractory glaucoma- Rising to the challenge of COVID-19 pandemic

“…[ 5 ] Comparative series of graft free scleral tunnel versus scleral patch graft by Rivera et al [ 6 ] and Pakravan et al [ 7 ] reported tube erosions in the later, but not in former group of patients. Alternate techniques like use of 6-mm graft free scleral tunnel,[ 8 ] needle-generated scleral tunnel, without a tube-covering patch[ 9 ] and long scleral flap, augmented with Tenon advancement and duplication[ 10 ] have also been described in literature.…”

Commentary: Do not judge a tube by its cover

“…This will ensure optimum utilization of scarcely available donor cornea and will also drive down costs. Some surgeons avoid the use of a PG altogether, either by creating a long tunnel[ 2 ] or by entering the anterior chamber (AC)/sulcus under a long scleral flap[ 3 ] or even by combining the tunnel and the flap. [ 4 ]…”