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

To create a balanced comparison of ab interno trabeculectomy (AIT) (Trabectome) and trabecular bypass stenting (TBS) (iStent).

Eye and Ear Institute, Pittsburgh, Pennsylvania, Ross Eye Institute, Buffalo, New York, and Glaucoma Associates of Texas, Dallas, USA.

Retrospective case series.

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.

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.

An exact matching comparison of AIT and TBS showed greater IOP reduction with fewer medications after AIT.