Purpose To compare the intermediate-term efficacy of Ahmed valve implants made of polypropylene versus silicone material in patients with refractory glaucoma.
Patients and Methods In February 2003, Jules Stein Eye Institute converted from the use of polypropylene to silicone Ahmed valve implants. 220 Ahmed valve implants performed before and after the conversion were retrospectively reviewed. 43 eyes with polypropylene and 47 eyes with silicone Ahmed valves were enrolled, which had been implanted for glaucoma refractory to medical treatment and filtering procedures, without previous drainage device or cyclodestructive procedures, and with a minimum of 1-year follow-up. The two groups were compared for IOP control, success rate, complications rate, and visual outcome.
Results IOP was significantly reduced in both the silicone and polypropylene Ahmed valve groups (from 32.77±12.74 mmHg to 14.14±5.31 mmHg, p≤0.0001; and from 30.88±10.64 mmHg to 15.56±6.92 mmHg, p≤0.0001, respectively) at 1-year. There was no significant difference of IOP control between the two groups at 1-year follow-up. However, there was a trend towards lower IOP in the silicone group compared to the polypropylene group (17.32±5.21 vs. 15.03±5.11 mmHg respectively, p=0.05) at 6-months, and the percent IOP reduction was significantly greater with the silicone group than the polypropylene group at 6-months (49.0±20.7% vs. 35±29.2% respectively, p=0.03). In addition, the silicone group required significantly fewer glaucoma medications at 1-year than polypropylene group (1.29±1.28 vs.1.86±1.28 respectively, p=0.05). There was no significant difference between the two groups with regard to rates of success, failure, hypotony or vision decrease, except that there was a significantly higher rate of devastating complication associated with silicone implant as compared to polypropylene (27.7% vs. 9.3% respectively, p=0.05). The 1-year survival rates for polypropylene and silicone Ahmed groups were 69.8% and 66.0% respectively (p=0.30).
Conclusion In a retrospective intermediate-term clinical comparison, the silicone Ahmed valve implant appears to be as effective as the polypropylene Ahmed valve in terms of pressure control, but may associate with a higher rate of complications.