Purpose: The authors evaluate a long posterior tube shunt device with a pressure sensitive valve for filtration surgery in eyes with recalcitrant glaucoma.
Methods: The device consisted of an anterior chamber tube connected to an oval (13 x 18 mm) episcleral explant. The explant was designed to maximize the area of surrounding encapsulation while still allowing implantation within one quadrant. A pressure-sensitive and unidirectional slit valve in the tube provided resistance to aqueous humor flow. One-stage implantation without the use of restrictive sutures was performed in 50 eyes with various types of glaucoma unresponsive to prior glaucoma surgery.
Results: Mean (+/- standard error of the mean) preoperative intraocular pressure (IOP) of 36.4 +/- 1.6 mmHg was reduced significantly (P < 0.001) to 8.3 +/- 1.3 mmHg on the first postoperative day. Mean anterior chamber depth (scale, 0-4+) was 3.4 +/- 0.1. Mean IOP 1 month after surgery was 14.1 +/- 1.3 mmHg. The implant was removed from four eyes due to IOP failure (1 eye), external erosion (2 eyes), or endophthalmitis (1 eye). A suprachoroidal hemorrhage occurred in one eye on the first postoperative day. Diplopia developed in one eye after surgery. Mean IOP at last follow-up examination (mean, 25.4 +/- 2.4 months; range, 16-36 months) was 13.1 +/- 1.3 mmHg. Intraocular pressure was 19 mmHg or lower in 80% of the eyes, 59% of which were without adjunctive antiglaucoma medications.
Conclusions: Design features of the Krupin Eye Valve with Disk result in a large area of encapsulation in a single ocular quadrant which functions as an external reservoir for passage of aqueous humor. The valve portion facilitates maintenance of anterior chamber depth during the early postoperative interval. This new therapeutic device can be effective in the long-term control of IOP in glaucomatous eyes not responsive to prior filtration surgery with adjunctive antimetabolite therapy.