Trabeculectomy showed higher cumulative probability of success than valve in lowering IOP

Br J Ophthalmol. 2009;93(11):1504-1509.

A study comparing long-term IOP-lowering results of trabeculectomy with mitomycin C and Ahmed glaucoma valve implantation found that filtering surgery had a higher cumulative probability of success of IOP reduction from baseline.

The study looked at 78 patients with open-angle glaucoma who had an Ahmed glaucoma valve (New World Medical) implanted and 88 open-angle glaucoma patients who had trabeculectomy with MMC. Cases in the two groups were matched by age, preoperative surgery, preop IOP and preop medicine. There was a minimum of 3 years of follow-up.

Cumulative probability of success was determined as either an IOP of 21 mm Hg or less with a reduction of IOP of 15% or more from baseline (criteria A), or as an IOP of 18 mm Hg or less with a reduction of IOP of 20% or more from baseline (criteria B). Cases also had to have no additional glaucoma surgery, hypotony or light perception loss for success.

"The 5-year cumulative probability of success was not statistically significant between eyes that had an [Ahmed glaucoma valve] or trabeculectomy with MMC when success was defined as criteria A (P = .094)," the study authors said. "However, when success was defined according to criteria B, eyes undergoing trabeculectomy with MMC had a higher rate of success (P = .024)."