['To investigate the long-term surgical outcomes of the Baerveldt 250 mm2 versus Baerveldt 350 mm2 glaucoma drainage implants (GDIs) (Abbott Laboratories Inc., Abbott Park, IL) in the treatment of refractory glaucoma.', 'Comparative case study.', 'A total of 89 consecutive eyes in 86 patients treated at Dean McGee Eye Institute between January 2006 and December 2008.', 'We retrospectively reviewed patient data from the following postoperative visits: 1 week, 1 month, 2 months, 3 months, 6 months, and every 3 months thereafter. Postoperative complications were also recorded. The mean follow-up time was 40 months (range, 2-78 months) for the Baerveldt 250 mm2 group and 31 months (range, 3-75 months) for the Baerveldt 350 mm2 group.', 'The primary outcome measure was surgical success. Secondary outcome measures included visual acuity (VA), intraocular pressure (IOP), and number of medications.', 'There was no difference in surgical success (P=0.98). No significant differences were observed in VA measured using the logarithm of the minimum angle of resolution (logMAR) scale, IOP, and number of medications at the last visit (P=0.09, 0.23, and 0.82, respectively). Complication and failure rates were comparable (P=0.82 and 0.64, respectively).'] Do long-term efficacy of the Baerveldt 250 mm2 compared with the Baerveldt 350 mm2 implant?