[Nonpenetrating deep trabeculectomy treated with mitomycin C, without implant. A prospective evaluation of 55 cases]

Since 1998 we have been conducting a prospective study of nonpenetrating deep trabeculectomy with chronic open-angle glaucoma to evaluate the efficiency of the technique.

The study was carried out in 55 eyes of 41 patients who suffered from open-angle glaucoma. After performing a superior scleral flap, mitomycin diluted to 0.01% was applied for 3 minutes, then the 4 x 4-mm superficial scleral flap was dissected at two-thirds deepness until reaching the cornea. The Schlemm canal and the external trabecula were surgically removed and the two points of the Schlemm canal were catheterized with a trabeculotome to ensure that the ablation was well done. If it was not, it was completed by using a trabeculotome as a guide. Postoperatively, if the filtering bleb tended to decrease or ocular pressure began to increase, the operated trabecular region was reopened with Yag laser. The filtering bleb characteristics were correlated with the normalization of intraocular pressure in the first 30 cases.

Preoperative pressure without treatment was 32 mmHg. Postoperative intraocular pressure without treatment was 20 mmHg or less in 79% of the eyes after 4 months, 77.5% after 6 months, 75% after 8 months and 61% after 12 months. By adding a local hypotension treatment in monotherapy, a pressure of 20 mmHg or less was obtained in 79% of the cases after 12 months. No severe complications were observed. The presence of a filtering bleb is an important factor in the normalization of postoperative pressure (p=0.0048).

This surgical technique provides a substantial decrease in intraocular pressure and very few complications after 12 months of follow-up.