Clinical experience of e-PTFE membrane implant surgery for refractory glaucoma

Abstract

Aims: To evaluate the clinical efficacy of membrane tube implant made of expanded polytetrafluoroethylene (e-PTFE, Gore-Tex) membrane and silicone tube in treating refractory glaucoma.

Methods: A retrospective chart review was performed on 43 eyes of 40 patients who underwent glaucoma tube shunt implant surgery using double layered e-PTFE membrane and silicone tube to treat refractory glaucoma. The surgeries were performed from May 1991 to September 1995, and the subjects were patients with terminal glaucoma without useful vision on the study eye.

Results: The mean follow up period was 32.9 months. The Kaplan-Meier survival for intraocular pressure (IOP) control (IOP between 6 and 21mm Hg without significant complication) was 80.9% at 1 year, 73.9% at 2 years, and 62.2% at 3 years after surgery. After excluding three eyes of three patients who were dropped within 3 months after surgery and did not have any serious complication or problem in IOP control, the average preoperative IOP was 42.5 (SD 14.6) mm Hg and IOP on the last visit was 17.3 (10.2) mm Hg (p = 0.000, n = 40). The number of antiglaucoma medications before surgery (2.2 (0.6)) was reduced to 0.5 (0.8) on the last visit (p = 0.000). The IOP was controlled within the range of 6-21 mm Hg in 26 eyes (65.0%). In the remaining 14 eyes (35%), we could not control the IOP or additional surgery was needed to control the IOP or to treat severe complications. Two cases of endophthalmitis and three of phthisis were found as serious complications. The other complications were similar to those of other commercially available glaucoma implants.

Conclusion: A comparable clinical result was obtained with this new implant as with the other commercially available implants. This implant with a thin and non-rigid reservoir has a potential to reduce some complications associated with the large volume and rigid consistency of the other implants, although it is not yet proved. This membrane tube implant may be considered as another substitute in the surgery of refractory glaucoma.

Figure 1

Membrane tube implant made of silicone tube and e-PTFE membrane. Arrow: silicone tube, one end fixed between two layers of e-PTFE membrane. Arrowheads: 5–0 nylon intraluminal stent passing through the silicone tube and between the e-PTFE membranes. e-PTFE = expanded poly(tetrafluoroethylene) membrane reservoir.

Figure 2

Scheme of the membrane tube implant surgery. Arrows: silicone tube connecting from the anterior chamber to the membrane reservoir. Arrowheads: anchoring sutures for silicone tube and e-PTFE membrane onto sclera with 10–0 nylon. SPG = donor scleral patch graft, e-PTFE = expanded poly(tetrafluoroethylene) membrane reservoir.

Figure 3

The change of intraocular pressure (IOP) before and after membrane tube implant surgery. The number of study eyes at each time interval were as follows; 40 at 1 week, 38 at 1 month, 33 at 6 months, 28 at 1 year, 22 at 2 years, 18 at 3 years, 17 at 4 years, 11 at 5 years, 6 at 6 years, and 1 at 7 years.

Figure 4

The Kaplan-Meier survival curve for the intraocular pressure control (between 6 and 21 mm Hg).

Figure 5

The examples of filtering blebs around the membrane-tube implant, transverse view by standardised echography (Ophthascan S, Biophysic Medical, France); (A) no visible filtering space, (B) a narrow fluid space, (C) moderate height filtering bleb with central echo relevant to the silicone tube, (D) a large filtering bleb with scleral flattening. No echo associated with the thin e-PTFE membrane was noticed.