Sustained Kmax Regression After Standard Epithelium-Off Cross-Linking In Young Keratoconus With High Baseline Kmax

To report long-term tomographic and visual outcomes of young keratoconus patients demonstrating marked corneal flattening following standard epithelium-off Dresden protocol corneal cross-linking (CXL).

Single-center retrospective case series conducted at a tertiary referral cornea clinic.

Three patients (four eyes; mean age 25.6 years) with elevated baseline Kmax values underwent standard epithelium-off CXL (0.1% riboflavin for 30 minutes followed by UVA irradiation at 9 mW/cm² for 10 minutes; total fluence 5.4 J/cm²). Patients were followed for 2.5–4.5 years. Maximum keratometry (Kmax), minimum corneal thickness (MCT), posterior elevation (PE), and corrected distance visual acuity (CDVA) were analyzed.

Mean preoperative Kmax was 55.39 D and decreased to 49.46 D at final follow-up (mean Δ−5.93 D) over 2.5–4.5 years. Two eyes demonstrated >5.0 D flattening, including one eye with a 9.26 D reduction. CDVA improved in all eyes, with three achieving 20/20. Mean minimum corneal thickness decreased from 458.5 µm to 415.8 µm, largely influenced by one eye with marked thinning, while other eyes remained relatively stable. Posterior elevation changes were variable (mean ΔPE +3.0 µm) and did not demonstrate a consistent pattern of posterior progression suggestive of biomechanical worsening despite significant anterior flattening. No evidence of clinical ectatic progression or vision-threatening complications was observed during follow-up.

While corneal cross-linking is primarily regarded as a stabilizing intervention, our findings demonstrate that substantial and sustained corneal flattening may occur in selected young keratoconus patients with elevated baseline Kmax values. Despite heterogeneous corneal thickness changes, no clinical or tomographic evidence of progressive ectasia was observed during long-term follow-up. The magnitude of regression appears greater than commonly reported in large prospective studies, suggesting a pronounced biomechanical remodeling response in certain steep phenotypes. Although limited by small sample size, these findings indicate potential reshaping beyond simple stabilization.