Miniature glaucoma implant effective, but high complication rate

Implanting a miniature glaucoma shunt under the conjunctiva in patients with open-angle glaucoma who are also undergoing cataract surgery may result in a relatively high number of complications, despite good IOP control in uncomplicated cases, according to a study by researchers in Switzerland.

"Refinement in the tube design and implantation technique would increase the success rate," the study authors said.

Delphine Rivier, MD, and colleagues at the University of Lausanne reviewed outcomes for 35 eyes of 35 patients implanted with the Ex-PRESS R-50 shunt (Optonol) for open-angle glaucoma between November 2000 and June 2002. All patients underwent temporal clear corneal phacoemulsification with IOL implantation first, according to the study.

"The ophthalmic viscosurgical device was not removed, and the Ex-PRESS R-50 was implanted under the conjunctiva into the anterior chamber," the authors said.

Patients averaged 74.6 years of age and were evaluated at up to 48 months postoperatively.

The mean IOP decreased from 19.3 mm Hg preoperatively to 15.3 mm Hg at 6 months, 15.1 mm Hg at 12 months, 13.8 mm Hg at 24 months, 14.6 mm Hg at 36 months and 13.3 mm Hg at 48 months (P < .005), the authors reported.

In addition, best corrected visual acuity averaged 0.74, and medication use decreased by 57% (P < .005) at 48 months follow-up, according to the study.

The researchers removed the microtube from 10 patients and performed bleb management in 10 eyes. Without medication, 10 patients (32%) had satisfactory IOP control, with pressure averaging 13.2 mm Hg.

Investigators also observed minor transient complications in 10 patients.

"Based on the cumulative survival curve after 48 months, the complete success rate was 32.7% and the qualified success rate, 53.7% (P < .05)," the authors said.

The study is published in the November issue of Journal of Cataract & Refractive Surgery.