Comparison of Femtosecond-assisted Laser In Situ Keratomileusis (FS-LASIK) and Keratorefractive Lenticule Extraction (KLEx) in Steep Keratometry

Abstract

Background This study evaluates the impact of steep preoperative keratometry on postoperative refractive, visual, and higher-order aberration (HOA) outcomes in femtosecond-assisted laser in situ keratomileusis (FS-LASIK) and keratorefractive lenticule extraction (KLEx) procedures for moderate myopia and low astigmatism.

Patients and Methods A retrospective analysis of 120 eyes from 120 patients who underwent FS-LASIK or KLEx between 2019 and 2023 was performed. Patients were divided into a steep keratometry group (Kmax 46 – 49 D) and a control group (Kmax 42 – 46 D). Uncorrected (UDVA) and corrected distance visual acuity (CDVA), spherical equivalent (SE), keratometry values, corneal thickness, and HOAs were assessed preoperatively and at six months postoperatively.

Results Postoperative UDVA was lower in the KLEx group compared to FS-LASIK (p < 0.05). SE was more myopic in the KLEx group, probably due to differences in ablation profiles and corneal biomechanics. HOAs increased in all groups, with a significant rise in spherical aberration except in KLEx eyes with steep corneas.

Conclusion FS-LASIK and KLEx were effective and safe in eyes with steep preoperative keratometry. However, KLEx resulted in slightly more residual myopia, and postoperative HOAs varied by procedure and preoperative keratometry. Individualized surgical planning is essential, and further prospective studies are needed to assess long-term outcomes.

Zusammenfassung

Hintergrund Diese Studie untersucht den Einfluss einer präoperativ steilen Keratometrie auf refraktive, visuelle Ergebnisse und hochgradige Aberrationen (HOAs) nach femtosekundenlaserassistierter In-situ-Keratomileusis (FS-LASIK) und keratorefraktiver Linsenextraktion (KLEx) bei Patienten mit moderater Myopie und geringem Astigmatismus.

Patienten und Methoden Es wurde eine retrospektive Analyse von 120 Augen von 120 Patienten durchgeführt, die zwischen 2019 und 2023 entweder einer FS-LASIK- oder KLEx-Behandlung unterzogen wurden. Eingeschlossen wurden Patienten mit einer Kmax < 49 dpt; als Kontrollgruppe dienten Patienten mit einer Kmax von 42 – 46 dpt. Unkorrigierte (UDVA) und korrigierte Fernvisuswerte, sphärisches Äquivalent (SE), Keratometriewerte, Hornhautdicke sowie HOAs wurden präoperativ und 6 Monate postoperativ erfasst.

Ergebnisse Die postoperative UDVA war in der KLEx-Gruppe signifikant geringer als in der FS-LASIK-Gruppe (p < 0,05). Das SE war in der KLEx-Gruppe myoper, was wahrscheinlich auf Unterschiede in den Ablationsprofilen und der Hornhautbiomechanik zurückzuführen ist. Die HOAs nahmen in allen Gruppen zu, wobei insbesondere die sphärische Aberration deutlich anstieg – mit Ausnahme der KLEx-Patienten mit steiler Hornhaut.

Schlussfolgerung FS-LASIK und KLEx erwiesen sich bei Patienten mit steiler präoperativer Keratometrie als wirksam und sicher. KLEx führte jedoch zu einer geringfügig höheren residualen Myopie, und die postoperativen HOAs variierten je nach Verfahren und Ausgangstopographie. Eine individualisierte chirurgische Planung ist entscheidend, und weitere prospektive Studien sind notwendig, um Langzeitergebnisse zu bewerten.

Conclusion Box

Already known:

• Preoperative corneal curvature is a critical factor influencing the predictability and safety of refractive surgery outcomes.

• Femtosecond-assisted laser in situ keratomileusis (FS-LASIK) and keratorefractive lenticule extraction (KLEx) are both established procedures with generally comparable visual and refractive results in myopic eyes.

• However, it has remained unclear whether steep preoperative keratometry values differentially affect postoperative refractive and aberrometric outcomes between FS-LASIK and KLEx procedures.

Newly described:

• This study demonstrated that both FS-LASIK and KLEx are effective and safe in eyes with steep preoperative keratometry, with no major differences in visual acuity or efficacy indices.

• KLEx-treated eyes with steep corneas showed slightly greater residual myopia compared to FS-LASIK–treated eyes, possibly due to differences in corneal biomechanics and energy delivery.

• Steep corneas exhibited less postoperative spherical aberration after KLEx than after FS-LASIK, suggesting that corneal curvature influences the induction of higher-order aberrations depending on the surgical technique.

Keywords

FS-LASIK - higher-order aberrations - KLEx - steep keratometry

Schlüsselwörter

FS-LASIK - Aberrationen höherer Ordnung - KLEx - steile Keratometrie

Publication History

Received: 16 May 2025

Accepted: 23 October 2025

Article published online:
26 February 2026

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