Trabeculectomy Versus EX-PRESS Shunt Versus Ahmed Valve Implant: Short-term Effects on Corneal Endothelial Cells

To evaluate short-term changes in corneal endothelial cells after trabeculectomy, EX-PRESS device implantation, and Ahmed valve implantation for the treatment of primary open-angle glaucoma.

Prospective, interventional, comparative case series with contralateral eye control study.

We prospectively evaluated the changes in number, density, and shape of the corneal endothelium cells in 128 eyes of 64 patients divided into 3 groups depending on the treatment received. Corneal specular microscopy was performed with a noncontact specular microscope preoperatively and at 1 and 3 months after surgery. The changes at each time point were compared with those of the control group, which consisted of 32 contralateral glaucomatous eyes receiving antiglaucoma medications without any previous glaucoma surgery.

In the subjects who underwent trabeculectomy, corneal endothelial cell density (ECD) significantly decreased by 3.5% (P = .012, paired t test) at 1 month and 4.2% (P = .007) at 3 months after surgery, compared to the baseline values. In the Ahmed valve group ECD did not change at 1 month after surgery and had a significant 3.5% decrease at 3 months (P = .04). In the patients who underwent EX-PRESS implantation and in the control group ECD did not change either at 1 month or at 3 months after surgery (P > .05).

EX-PRESS shunt, compared to trabeculectomy and Ahmed valve, seems to be a safer procedure regarding the risk of endothelial cell loss. For this reason, it may be the treatment of choice in patients with significant low corneal ECD before surgery or other risk factors for corneal damage.