Clinical outcomes of ray tracing-guided LASIK for myopic astigmatism correction.

PURPOSE: To evaluate real world clinical outcomes of Ray Tracing-Guided LASIK for the correction of various degrees of myopic astigmatism.

METHODS

A retrospective analysis of patients who underwent Ray Tracing-Guided LASIK. The safety, efficacy, stability, and predictability of the surgery were also analyzed. Vector analysis was used to assess astigmatism outcomes at 3 months postoperatively. Subgroup analysis was performed for different degrees of astigmatism to explore the ablation designs for each group.

RESULTS

A total of 309 patients (586 eyes) were included in this study. At 3 months postoperatively, 586 eyes (100.0%) achieved uncorrected distance visual acuity (UDVA) of 20/25 or better, and 579 eyes (98.81%) achieved a UDVA of 20/20 or better. No eye lost two or more lines of UDVA compared to preoperatively. Refractive outcomes showed manifest refraction spherical equivalent (MRSE) within ±0.5D in 466 eyes (79.52%) and within ±1.0D in 578 eyes (98.63%). For eyes with astigmatism <1.0DC, the correction index (CI) was 1.33±0.61 and index of success (IOS) was 0.85±0.75, indicating overcorrection. The Angle of Error (AofE) was within ±15° in 74.89% of eyes with <1.0D cylinder, 99.23% with 1.0-2.0D, and 100% with ≥2.0D As the astigmatism cylinder increased, CI and IOS values decreased.

CONCLUSIONS

Ray Tracing-Guided LASIK demonstrated safety, efficacy, predictability and stability for correcting myopic astigmatism. Ablation profile and treatment should be adjusted for patients with low and high astigmatism. However, overcorrection or undercorrection of various degrees of myopic astigmatism may also occur if the sightmap measurements are significantly different from the manifest refraction.