Development and Application of a New T-shaped Internal Trabeculotomy Hook (T-hook)

PURPOSE: We introduce a newly designed T-shaped internal trabeculotomy hook and compare its surgical outcomes with those of Kahook dual blade (KDB) surgery. PATIENTS AND METHODS: One eye each of seventeen and sixty-one patients underwent T-hook and KDB surgeries, respectively. Post-surgical intraocular pressure (IOP), medications, visual acuity, and prevalence of IOP spikes and hyphema were compared between the two cohorts. RESULTS: The utility of the T-hook was excellent and enabled the easy opening of the Schlemm’s canal. The pre-surgical IOP of 25.6 ±7.5 mmHg in the T-hook cohort decreased to 14.1 ± 4.3 (−41.2% reduction) and 15.0 ± 3.1mmHg (−39.3% reduction) at 3 (P<0.001) and 6 months (P=0.003), respectively. Pre-surgical medications of 2.8 decreased to 2.3 and 2.0 medications, respectively, at 3 and 6 months. The best-corrected visual acuity (BCVA) improved from the pre-surgical logarithm of the minimum angle resolution (logMAR) of 0.148 to −0.012 at three months (P=0.036,). While the pre-surgical IOP of 24.9±4.3 mmHg in the KDB cohort decreased to 16.5±5.7 mmHg (−35.5%, P<0.001) and 16.1±3.4 mmHg (−33.5%, P<0.001) at 3 and 6 months, respectively. Reduction in medications at 3- and 12-month timepoints (from 2.8 to 1.7 and 1.7, respectively; P<0.001) and improvement in BCVA at three months (from 0.106 to −0.025 logMAR, P<0.001) were also significant. There was no difference between the T-hook and KDB cohorts in terms of the pre-surgical IOP (P=0.15) and post-surgical IOP at 1 (P=0.27), 3 (P=0.17), 6 (P=0.47), and 12 months (P=0.11, Mann–Whitney U-test). The prevalence of a post-surgical IOP spike in the T-hook and KDB cohorts was 41.2% and 47.5%, and that of post-surgical hyphema was 17.6% and 26.2%, respectively. CONCLUSION: The novel T-hook was easy to use and was as useful as the KDB device in performing internal trabeculotomy.