Comparison of Postoperative Higher Order Aberrations After Surface Ablations by 2 Types of Ablation Protocols: Aberration-Free and Cornea Wavefront-Guided Using High-Repetition Excimer Laser

Kang, David

Comparison of Postoperative Higher Order Aberrations After Surface Ablations by 2 Types of Ablation Protocols: Aberration-Free and Cornea Wavefront-Guided Using High-Repetition Excimer Laser

Friday, April 17, 2015

KIOSKS (San Diego Convention Center)

David Sung Yong Kang, MD

Byoung Jin Ha, MD

Hun Lee, MD

Jin Young Choi, MD

Eun Kyung Kim, MD

Tae-im Kim, MD

Purpose
To evaluate and compare the clinical outcomes and post operative high order aberrations of surface ablations to correct myopic astigmatism using two types of ablation protocols; aberration free(Ab-F) and corneal wavefront guidedCOWAVE) with a high repetition 1050 Hz excimer laser.

Methods
Non-interventional, cross-sectional comparative observational case series. Patients with myopic astigmatism (spherical equivalent -0.50 to -11.63 diopters [D]), a corrected distance visual acuity (CDVA) of 20/20 or better, and an estimated residual bed thickness of 300 μm or more had surface ablation randomized to two protocols; aspheric aberration-free ablation profile (Ab-F) and corneal wavefront guided profile (COWAVE) of the 1050 Hz scanning-spot laser. Study parameters included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, and higher-order aberrations (HOAs) at 6 months.

Results
The study included 157 eyes (79 patients). At 6 months, 98.6% of eyes had a UDVA of 20/20 or better and 100% had 20/32 or better. HOAs increased postoperatively (P<.001), with mean total postoperative corneal HOAs of 0.69 μm ± 0.23 (Ab-F) and 0.61 ± 0.21 μm (COWAVE), respectively. The increase of all HOAs was significantly less in the COWAVE group (Ab-F:0.19 ± 0.26 vs 0.11 ± 0.23;p=0.03). Also, Coma significantly decreased from 0.30 μm ± 0.17 to 0.21 μm ± 0.14 for the COWAVE group (p=0.001). In Subgroup analyses, there was a significant trend for the reduction of coma to be higher in those eyes with higher pre-operative coma (R=-0.702, P=0.01).

Conclusion
Surface ablations with both the AB-F and COWAVE ablations were safe and efficacious. There was a significantly less increase for all measured HOAs in the COWAVE group. The level of coma was significantly reduced after COWAVE ablations and this trend was greater for eyes with higher preoperative levels of coma.