To report the 18-month clinical outcomes of the progressively higher fluence pulsed light (7.2 to 10 J/cm²) epithelium-on accelerated corneal crosslinking (PFPL M Epi-On ACXL) protocol for progressive keratoconus.

This was a prospective, non-randomized interventional study. Fluence was assigned based on preoperative pachymetry: 7.2 J/cm² (≤420 μm), 8.6 J/cm² (420–459 μm), or 10 J/cm² (≥460 μm). Riboflavin solutions (Paracel I and II), pulsed ultraviolet-A (UVA) irradiation (1s on/off), and consistent procedural timing (13min irradiation) were applied using the KXL I system. Uncorrected and best-corrected distance visual acuity (UDVA, CDVA), maximum keratometry (Kmax), higher-order aberrations (HOAs), and anterior segment optical coherence tomography (OCT) demarcation line depth were analyzed at baseline, 6, 12, and 18mo.

Totally 32 eyes of 32 patients aged over 26y with progressive keratoconus underwent PFPL M Epi-On ACXL were included. All groups demonstrated long-term stability in UDVA and CDVA. The 10 J/cm² group showed the greatest improvement in CDVA (+0.17 decimal), significant corneal flattening (Kmax reduction: −1.03 D), and the most substantial HOAs reduction (−0.30 µm). No significant differences were observed between the 7.2 and 8.6 J/cm² groups. OCT showed fluence-dependent demarcation line depths: 250±30 µm in the 10 J/cm² group. No adverse events were observed.

PFPL M Epi-On ACXL appears to be a safe, repeatable, and effective long-term treatment for progressive keratoconus. The 10 J/cm² fluence is associated with better optical and structural outcomes compared with lower fluences. Consistency in protocol application is essential to ensure efficacy.