Effect of Excisional Goniotomy with the Kahook Dual Blade (KDB) on Surgically Induced Astigmatism

Purpose: To determine the effect of Kahook Dual Blade goniotomy with phacoemulsification (Phaco-KDB) compared to phacoemulsification alone (Phaco) on surgically induced astigmatism (SIA).

Design: Prospective study.

Participants: Forty eyes of 28 patients treated with Phaco-KDB and 20 eyes of 13 patients treated with Phaco between 12/27/16 and 7/23/19 with a minimum 1 month follow-up were prospectively enrolled.

Methods: Corneal astigmatism was assessed pre- and post-operatively using the simulated K (simK) values from the Pentacam Holladay report.

Main outcome measures: SIA was compared between Phaco-KDB and Phaco groups using mean magnitude SIA, rate of ≥0.50 D SIA, and SIA centroids.

Results: The difference in mean magnitude SIA was not statistically significant between Phaco-KDB and Phaco (mean = 0.28 D and 0.25 D, respectively, P = 0.621). The difference in the rate of ≥0.50 D SIA was not statistically significant between Phaco-KDB and Phaco (11.6% and 10.0%, respectively, P = 1.00). The SIA centroid for Phaco-KDB was 0.05 D @ 51° ± 0.40 D and 0.07 D @ 3° ± 0.32 D for Phaco.

Conclusion: Neither the mean magnitude SIA nor the rate of astigmatic change ≥0.50 D was significantly different between Phaco-KDB and Phaco groups. SIA centroids between groups showed comparable and negligible effect on corneal astigmatism. KDB combined with phacoemulsification may not significantly affect SIA compared to phacoemulsification alone based on postoperative topography and is likely an astigmatically neutral procedure.