Two-year data comparison of ab interno trabeculectomy and trabecular bypass stenting using exact matching

Purpose: To create a balanced comparison of ab interno trabeculectomy (AIT)(Trabectome)and trabecular bypass stenting (TBS)(iStent). Setting: Eye and Ear Institute, Pittsburgh, Pennsylvania, Ross Eye Institute, Buffalo, New York, and Glaucoma Associates of Texas, Dallas, USA. Design: Retrospective case series. Methods: The primary outcome measure was an unmedicated intraocular pressure (IOP)of 21 mm Hg or less and the secondary measure was an unmedicated IOP reduction of 20% or more at 2 years. Patients were matched by baseline IOP, number of glaucoma medications, and glaucoma type using exact matching and by age using nearest neighbor matching. Individuals without a close match were excluded. All surgeries were combined with phacoemulsification. Results: One hundred fifty-four AIT eyes and 110 TBS eyes were analyzed. Forty-eight AIT patients were exactly matched with 48 TBS patients. Both groups had a mean baseline IOP of 15.3 mm Hg ± 3.1 (SD). At 24 months, the mean IOP was 13.9 ± 3.3 mm Hg in AIT patients and 16.8 ± 2.8 mm Hg in TBS patients and the mean number of medications was 0.7 ± 1.0 and 1.7 ± 1.2, respectively (both P =.04). At 24 months, the IOP was 21 mm Hg or less without medications in 53% of AIT patients and 16.6% of TBS patients (P <.05). At that time, 17.6% of patients in the AIT group but no patient in the TBS group had an IOP reduction of 20% or more without medication. Conclusion: An exact matching comparison of AIT and TBS showed greater IOP reduction with fewer medications after AIT.