Baerveldt-350 implant versus Ahmed valve for refractory glaucoma: a case-controlled comparison

To compare the efficacy of intraocular pressure (IOP) control of the Baerveldt-350 implant with tube ligature and the Ahmed valve in patients with refractory glaucoma.

Four hundred seventy glaucoma drainage device procedures from July 1995 to July 2001 (6 years) were reviewed retrospectively. Thirty-two cases of Baerveldt-350 implantation performed in patients with glaucoma refractory to medical treatment and filtering procedures, without previous drainage device or cyclodestructive procedures, and with a minimum of 1-year follow-up were identified. Thirty-two cases of Ahmed valve implantation were matched case by case with 32 Baerveldt-350 cases for age, race, gender, glaucoma subtype, previous ocular history, preoperative IOP, and surgeon who performed the implantation. The two groups were compared for IOP control, visual outcome, complication rate, and surgical success rate. Surgical success rate was defined as an IOP reduction greater than or equal to 30% and final IOP more than 5 mm Hg and less than 22 mm Hg, without devastating complications.

Over a follow-up period of 1 year, no statistically significant differences were detected between the Baerveldt-350 implant versus Ahmed valve for IOP control (12.1 +/- 5.3 mm Hg vs. 13.6 +/- 5.6 mm Hg respectively, at a power of 90% to detect a difference of 3.2 mm Hg between the two groups and P = 0.05), surgical success rate (65.6% vs. 65.6% respectively, complete and qualified combined), postoperative hypotony rate (37.5% vs. 34.4% respectively), and visual acuity changes of more than 1 line in Snellen visual acuity (43.3% vs. 29.0% respectively).

In a case-controlled comparison, the Baerveldt-350 implant and the Ahmed valve had similar IOP control and surgical outcomes in patients with refractory glaucoma at 1-year follow-up.