Valve implants may be effective for uveitic glaucoma

Immunomodulatory therapy is an important factor of one study’s success rate.

BOSTON — Valve implants can control uveitic glaucoma, and immunomodulatory therapy plays a key role in controlling the condition postoperatively, researchers said.

Uveitic glaucoma is much more difficult to treat successfully than other types of glaucoma, according to C. Stephen Foster, MD. He told Ocular Surgery News, “The fact that inflammation is in the picture makes the problem much worse and makes treatment successes much fewer.”

Uveitic glaucoma has a similar elevated intraocular pressure (IOP) level as other glaucomas, but it is much more resistant to treatment, Dr. Foster said.

Trabeculectomy has a poor track records for long-term treatment of uveitic glaucoma, Dr. Foster said. Valves lower the pressure effectively, so surgeons studied their use to maintain IOP between 5 mm Hg and 20 mm Hg and to reduce the incidence of hypotony. Immunomodulatory therapy aided the outcomes.

Dr. Foster reported the results of the retrospective, noncomparative case series in the November 1999 issue of Ophthalmology.

Valves implanted

Surgeons implanted Ahmed valves with 185 mm² surface area in 21 eyes of 19 patients. Each patient had chronic uveitis, uncontrolled IOP, progressive visual field loss or progressive optic disk cupping.

Uveitis had to be controlled preoperatively, although not absolutely so.

All patients received an intensified immunosuppressive regimen with adjunctive prednisone (1 mg/kg/day). Surgeons continued the regimen to minimize inflammation, which may contribute to fibrosis and scar formation.

Postoperatively, surgeons looked at IOP between 5 mm Hg and 21 mm Hg, the number of glaucoma medicines required, visual acuity and complications as outcome measures.

The researchers wrote in Ophthalmology that the average preoperative IOP was 35.1 mm Hg, but “markedly” fell after Ahmed valve placement to 11.6 mm Hg. All patients had long-term controlled IOP between 5 mm Hg and 18 mm Hg after surgery.

The average number of preoperative medications was 3.5. This fell to 0.6 medications after implantation. Researchers wrote that 14 eyes did not require medications, five needed fewer drugs and two needed the same number as before.

Nine eyes maintained Snellen acuity and 12 eyes improved Snellen acuity.

“This retrospective analysis suggests that the implantation of the Ahmed glaucoma valve in patients with uveitic glaucoma is an effective means of controlling IOP,” the article stated.

Despite the need for multiple surgeries, the authors continued, only four eyes experienced surgical complications, none of which resulted in vision loss. One eye required penetrating keratoplasty that might have been attributed to the valve. However, the eye also had a failed Molteno implant, a previous cataract extraction, a pars plana vitrectomy and IOL explantation.

Control inflammation

Dr. Foster said immunomodulatory therapy was key in the success of the valves controlling uveitic glaucoma.

He attributed the high success rate of the study to aggressive treatment of active inflammation.

“Inflammation is a major culprit in ruining a perfectly good glaucoma operation,” he said. Chronic inflammation “sabotages” the filtering area and bleb. It leads to excessive fibrosis of the pseudocapsular area around valve-tube shunt devices. Uveitis also can damage the retina and optic nerve on its own.

For Your Information:

C. Stephen Foster, MD, FACS, can be reached at Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114 U.S.A.; +(1) 617-573-3591; fax: +(1) 617-573-3181. Dr. Foster has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.

DaMata A, Burk SE, Netland PA, Baltatzis S, Christen W, Foster CS. Management of uveitic glaucoma with Ahmed glaucoma valve implantation. Ophthalmology. 1999;106:2168-2172.