The "Deroofing" of Schlemm's Canal in Patients With Open-Angle Glaucoma Through Placement of a Collagen Drainage Device

Abstract

BACKGROUND AND OBJECTIVES: A preliminary study was conducted to examine a new surgical approach for the management of patients with open-angle glaucoma in which Schlemm's canal is opened to restore drainage in a nonpenetrating fashion. The authors compared the results of the surgical procedure including the new glaucoma drainage device with the results of standard trabeculectomy. PATIENTS AND METHODS: The authors performed a new type of surgical procedure on 58 consecutive patients with open-angle glaucoma. The procedure entails "deroofing" Schlemm's canal to facilitate the drainage of aqueous without penetrating the eye. This is done by exposing the canal after a partial-thickness sclerectomy and keratectomy along a 5-mm arc. After the canal was deroofed, a new type of collagen glaucoma drainage device was placed in the surgical site to maintain drainage postoperatively. Patient data, including intraocular pressure (IOP), complications, and the number of medications required to maintain adequate pressures, were analyzed for 1 year postoperatively. RESULTS: Within 1 to 2 months postoperatively, 80.9% of the patients achieved an IOP lower than 21 mm Hg. This improved to 88.9% at 3 to 6 months postoperatively and 87.5% at 6 to 12 months postoperatively. The only major complications were microperforations (8.6%) related to surgical technique and a few cases of high IOP that required repeat operations (10.3%). CONCLUSIONS: The nonpenetrating technique for deroofing the canal effectively allows the drainage of aqueous to acceptable levels (in the range of 15 to 17 mm Hg) without the complications associated with penetrating trabeculectomy. Complications are rare, and the collagen drainage device appears to be effective for allowing the drainage site to remain patent after its dissolution.