Implantation of second glaucoma drainage devices after failure of primary devices

BACKGROUND AND OBJECTIVE: To evaluate the efficacy and safety of implantation of a second glaucoma drainage device for eyes that have failed a primary device. PATIENTS AND METHODS: Medical records of patients receiving a primary glaucoma drainage device at Bascom Palmer Eye Institute from January 1987 to October 1998 were reviewed, of which 18 eyes of 18 patients were studied. Patients failing a primary glaucoma drainage procedure and receiving a second glaucoma drainage device were included in this study. The second eye in the same patient was excluded if a second drainage implant was required. All patients received a second device in a standardized fashion with the drainage tube inserted in the anterior chamber. Main outcome measures included: visual acuity, intraocular pressure (IOP), antiglaucomatous medication, length of follow up, and surface area of glaucoma drainage device. Success was defined as an IOP less than or equal to 21 mm Hg with or without medications, and at feast a 20% reduction in IOP, without the need for additional glaucoma procedures. RESULTS: The mean postoperative IOP (19.6 9.4 mm Hg; range, 8-50 mm Hg) was significantly (P 0.006) lower than the mean preoperative IOP (29.5 +/- 8.1 mm Hg; range, 20-52 mm Hg) at last follow up (mean 19.6 +/- 13.6 months; range, 6-47 months). The mean number of postoperative antiglaucomatous medications (2.2 +/- 1.2; range 0-4) was statistically similar (P = 0.2) to mean preoperative number of antiglaucomatous medications (2.6 +/- 1.2, range 1-4). Using Kaplan-Meier estimates, successful IOP reduction was observed in 89%, 83%, 63%, and 37% of eyes at 6 months, 1, 2, and 3 years, respectively. Four patients (21%) had a decline in visual acuity. CONCLUSIONS: Implantation of secondary glaucoma drainage devices may be useful in eyes that have failed primary devices.