OCT 05, 2009
Researchers retrospectively compared outcomes when the Ex-PRESS device was implanted under a partial-thickness scleral flap in glaucomatous eyes either as a single procedure (231 eyes of 200 patients) or in combination with phacoemulsification in eyes with visually significant cataract (114 eyes of 100 patients). Both groups received intraoperative mitomycin C. At three years, the success rate, was similar: 94.8 percent in the single procedure group and 95.6 percent in the combined treatment group. Interesting findings in the study included a higher rate of hypotony during the first postoperative week in the single procedure group, less of a change from baseline IOP in the combined procedure group and tube blockage (the most common device-related complication) in three patients in each group, which was successfully treated with the Nd:YAG laser.
The very high success rate in both groups may be a result of accepting a pressure of 21 mmHg as an indication of success. The authors suspect that the higher rate of hypotony in the noncataract group may have been due to retained viscoelastic used in the cataract patients, yet most surgeons who implant the Ex-PRESS device use viscoelastic and leave it in the eye post-surgically. The smaller change from baseline IOP in the cataract group was related primarily to a lower baseline pressure; the reason for this is not mentioned by the authors.
Tube blockage was due to vitreous in one patient. Typically, the most common reason for blockage is due to the iris, which assumes coverage of the whole tube, as the shunt has openings not only at its tip but on the superior aspect as well.
Dr. Freedman has no financial interests to disclose.