Purpose:
To examine the results of same-eye second GDD insertion in eyes with refractory glaucoma despite previous Ahmed GDD insertion.
Methods:
Non comparative retrospective case series.
Results:
21 patients who underwent insertion of two glaucoma drainage devices into the same eye between January 1999 and November 2007 were identified. 19 patients had follow up of at least 1 year and were included in the analysis. All surgeries involved Ahmed GDDs and were performed by a single surgeon (GT). Mean age at time of surgery was 58 years (median 60, range 37-81). Mean number of previous trabeculectomies in the operated eyes was 1.74 (median 2, range 0 to 4). The mean interval between insertion of the first and second Ahmed valves was 24.2 months (median 17, range 4-67). Mean follow up interval was 38.8 months (median 35 months, range 12-80 months).The IOP, number of glaucoma medications and LogMAR visual acuity (VA) at 12 months and at final follow-up was examined, and the results are shown in the table. P values are based on comparison with preoperative values using a Wilcoxon test, with a value of ≤0.05 considered to be statistically significant. The mean drop in IOP at 12 months and at final follow up was 8mmHg (43%) and 9.9mmHg (42%) respectively. Although the mean VA was poorer post-operatively this did not reach levels of statistical significance.16 of the 19 patients (84.2%) achieved IOP of ≥5mmHg and ≤21 mm Hg and ≥20% decrease on IOP prior to second GDD insertion with or without glaucoma drops.One patient required anterior chamber reformation on the first post-operative day and another suffered corneal decompensation which resulted in a decrease in VA from 20/70 pre-operatively to counting fingers post-operatively.
Conclusions:
In eyes with refractory glaucoma where IOP remains uncontrolled despite an Ahmed GDD insertion of a second GDD is effective in improving IOP control.
Keywords: intraocular pressure