COMPARISON OF CORNEAL HIGHER-ORDER ABERRATIONS AND TOPOGRAPHIC CHANGES FOLLOWING FEMTOSECOND LASER IN SITU KERATOMILEUSIS AND PHOTOREFRACTIVE KERATECTOMY IN MYOPIC EYES

To compare surgery induced alterations in corneal higher-order aberrations and topographic parameters after femtosecond laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK) in myopic eyes.

This study was conducted at the Department of Ophthalmology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Türkiye.

This retrospective comparative study included 56 eyes of 28 patients with myopia (≤ –5.0 D) and astigmatism (≤ –2.5 D) who underwent refractive surgery at the Department of Ophthalmology, Istanbul Faculty of Medicine, between February 2024 and February 2025. Among them, 28 eyes of 14 patients underwent PRK, and 28 eyes of 14 patients underwent LASIK. Preoperative and 3-month postoperative measurements were analyzed. Corneal higher-order aberrations (HOAs), including spherical aberration, coma, and trefoil, as well as topographic parameters (flat keratometry [K1], steep keratometry [K2], and anterior corneal asphericity [Q value]), were evaluated using a rotating Scheimpflug camera (Pentacam HR, Oculus GmbH, Wetzlar, Germany). Statistical analyses were performed using SPSS software (version 21.0, IBM Corp., Armonk, NY, USA). Normality of data distribution was assessed with the Shapiro–Wilk test. Comparisons between groups were performed using independent-samples t-tests or Mann–Whitney U tests, as appropriate. A p value < 0.05 was considered statistically significant.

The mean age was 25.9±4.9 years (range, 20–40), with no significant difference between the LASIK and PRK groups in terms of age (p = 0.121) or gender distribution (p = 0.241). Preoperative refractive and topographic parameters, including manifest spherical refraction (p = 0.511), spherical equivalent (p = 0.149), K1 (p = 0.163), K2 (p = 0.987), and ablation depth (p = 0.064) were comparable between the two groups. Postoperatively, Q value increased in both groups without a statistically significant difference (p = 0.124). Total HOAs (p=0.110), spherical aberration (p=0.954), horizontal coma (p=0.432) and horizontal trefoil values (p=0.838) increased after surgery in both groups. Vertical coma values decreased postoperatively in both groups, with a significantly greater reduction observed in the LASIK group (mean change = –0.25 ± 0.34) compared to the PRK group (mean change = –0.05 ± 0.19; p = 0.014).

Both LASIK and PRK resulted in comparable changes in corneal HOAs and topographic parameters in myopic eyes. However, the reduction in vertical coma was more pronounced in the LASIK group. These findings indicate that variations in aberrations, which may affect postoperative visual quality, should be carefully considered when selecting the surgical technique. Further long term and randomized controlled studies are warranted to better understand the impact of these procedures on corneal optical quality and to guide surgical decision making.