Comparison Of Visual Outcomes Following Ray-Tracing-Guided Femtosecond Laser-Assisted In Situ Keratomileusis With Different Optical Zone Sizes

To investigate the influence of different optical zone (OZ) diameters on the clinical outcomes of ray-tracing-guided femtosecond laser-assisted in situ keratomileusis (FS-LASIK).

Aier Eye Hospital, GuangZhou，Affiliated to Jinan University

 In this retrospective analysis, 126 eyes from 63 patients who underwent ray-tracing–guided FS-LASIK were included. Eyes were stratified by the intended OZ diameter into a 6.5- group (6.0-6.5 mm) and a 6.5+ group (6.6-7.0 mm). All patients completed standardized preoperative and 3-month postoperative evaluations, which included measurements of uncorrected (UDVA) and corrected (CDVA) distance visual acuity, manifest refraction, mean keratometry, intended/achieved maximum ablation thickness, central corneal thickness, low-mesopic pupil diameter, 6-mm total ocular wavefront aberrations, and the Quality of Vision (QoV) questionnaire.

Both groups achieved  excellent and comparable refractive accuracy and stability. At 3 m, UDVA of 20/16 or better was attained in 80% (6.5– group) and 76% (6.5+ group; P = .797). CDVA improved by ≥1 line in 65% and 55%, respectively (P = .080). No significant differences were found in spherical equivalent, refractive astigmatism, astigmatism, difference vector, mean keratometry, central corneal thickness, or maximum ablation thickness (all P > .05). The 6.5+ group showed significantly lower total ocular wavefront aberrations over a 6-mm pupil, including higher-order aberrations (P = .005), spherical aberration (P = .016), coma (P = .013), and vertical coma (P = .023). Patient-reported QoV scores did not differ significantly between groups.

This study indicates that a larger OZ in ray-tracing-guided FS-LASIK achieves comparable visual acuity and refractive precision, yet induces significantly fewer total ocular wavefront aberrations at a 6-mm pupil diameter. Consequently, opting for a larger OZ can be recommended as a strategy to improve postoperative optical quality while maintaining safety and effectiveness in myopic patients.