Faster visual recovery with Ex-PRESS than trabeculectomy

COS 2012, July 3 - Glaucoma patients who undergo trabeculectomy are more likely to lose two or more Snellen lines than patients who receive an Ex-PRESS micro-shunt implant, according to a prospective randomized controlled trial of 64 glaucoma patients who underwent either trabeculectomy (31 patients) or who received an Ex-PRESS shunt (33 patients).

Results were presented in a talk by Laura Beltran-Agullo, a glaucoma fellow in ophthalmology at the University of Toronto, Toronto Western Hospital.

Intraocular pressure (IOP) reduction from the procedures was compared, and efficacy was evaluated. Secondary outcomes included visual acuity, among other measures. All patients completed three months of follow-up, 58 completed six months, and 43 completed one year.

At baseline, IOPs were similar between the Ex-PRESS and trabeculectomy groups, at 22.6 and 22.0, respectively. By the six-month point post-surgery, IOPs had dropped to similar levels: 10.2 and 10.3, respectively.

There were no significant differences in IOP between the two groups, but there were differences within the treatment groups. At six months, 45% of the trabeculectomy eyes had lost two or more Snellen lines compared with only 26% of the Ex-PRESS eyes. This was statistically significant with a p value of 0.03. A total of 12 patients overall had no vision loss (five in the trabeculectomy group, seven in the Ex-PRESS group).

Researchers were unable to determine why there was vision loss in the groups, nor why the loss was greater in the trabeculectomy than the Ex-PRESS group. However, other studies in the medical literature show similar rates of loss of visual acuity following filtration surgery.

Beltran-Agullo noted that a reduction in visual acuity after trabeculectomy is common, but transient. Some studies suggest it can take up to two years to resolve. There were no differences in complication rates between the trabeculectomy and Ex-PRESS groups.

Doctors should focus on visual acuity as well as pressures after surgery. Plus, patients need to be told before surgery that they may lose some visual acuity, but that without the surgery they are at risk of losing sight, Beltran-Agullo said.