Ray-Tracing-Guided Versus Q-Value-Adjusted Lasik For Myopic Astigmatism ≥ 2.00 Diopters: 3-Month Clinical Outcomes

To compare the safety, efficacy and predictability of ray-tracing-guided with Q-value-adjusted laser-assisted in situ keratomileusis (LASIK) for correcting myopic astigmatism of 2.00 Diopters (D) or greater at 3 months postoperatively.

The InnovEyes Sightmap (Alcon Management S. A., Fort Worth, United States) and Topolyzer (Alcon Management S. A., Fort Worth, United States) was performed in InnovEyes group and Custom-Q group, respectively. All flaps were created using WaveLight® FS200 femtosecond laser (Alcon Management S. A., Fort Worth, United States). the stromal bed was ablated with the WaveLight® EX500 excimer laser (Alcon Management S. A., Fort Worth, United States).

This retrospective, comparative clinical study included 60 eyes with myopic astigmatism ≥ 2.00 D: 30 eyes in the ray-tracing-guided group (InnovEyes group) and 30 eyes in the Q-value-adjusted group (Custom-Q group). Uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), manifest refraction spherical equivalent (MRSE), sphere and cylinder were evaluated preoperatively and 3-month postoperatively. General estimating equitation was used for inter-group comparison and correlation analyses to account for potential inter-eye correlation within subject.

At 3-month postoperatively, CDVA was better in the InnovEyes group (P = 0.005), with 87% of eyes achieving cylinder within ± 0.25 D (vs. 63% in the Custom-Q group). Vector analysis revealed InnovEyes group induced a slight overcorrection (correction index: 1.04 ± 0.02) versus Custom-Q group’s undercorrection (correction index: 0.94 ± 0.02) (P = 0.007), with InnovEyes group exhibiting significantly smaller magnitude of error (0.08 ± 0.04  vs. -0.13 ± 0.05, P = 0.002).Correlation analyses revealed that both correction index and magnitude of error were non-significant correlated with TIA in either group (all P > 0.05). The group × TIA interaction was also non-significant (both P > 0.05).

Ray-tracing-guided LASIK is an effective, safe, and predictable surgical option for eyes with myopic astigmatism ≥ 2.00 D. Although a tendency toward mild astigmatism overcorrection was noted, it achieved statistically better postoperative CDVA and small astigmatic errors compared to the Q-value-adjusted group at 3 months postoperatively.