Repeated Accelerated Local Corneal Collagen Crosslinking in the Treatment of Progressive Keratoconus

Study objective: To analyze the clinical, functional, and safety efficacy of accelerated local corneal collagen crosslinking (ALCCL) in patients with progressive keratoconus who had previously undergone crosslinking.
Patients and methods. A retrospective analysis of treatment outcomes was performed in 11 patients (12 eyes) with progressive keratoconus stages I–III (age 27 ± 6 years). The initial best-corrected visual acuity was 0.65 ± 0.11, the mean corneal refractive power was 53.1 ± 2.42 D, and the minimum stromal thickness was 459 ± 19.6 µm. Surgical treatment consisted of personalized crosslinking: local de-epithelialization of the cone apex and photosensitization with a 0.1% riboflavin solution, followed by UV irradiation (6 mW/cm²) for 15 minutes. Postoperative care included standard antibacterial, anti-inflammatory, and long-term keratoprotective therapy.
Results. This cohort of patients fully met the requirements for repeat crosslinking according to the UL-KRK protocol. Corneal condition was assessed at 6, 12, 18, and 36 months after the accelerated local crosslinking procedure. The uncorrected visual acuity (UCVA) increased from 0.32 ± 0.19 to 0.55 ± 0.15 by the 6-month follow-up and remained stable throughout the study. The BCVA did not change significantly (0.66 ± 0.16). According to the Pentacam HR device (Oculus, Germany), Kmax decreased from 53.1 ± 2.42 to 51.9 ± 1.09 D, and the cylindrical component (Cyl) decreased from –2.89 ± 1.02 to –1.95 ± 0.77 D. The formation of the demarcation line was visualized at a depth of 270–330 µm in the first 3 months according to corneal optical coherence tomography (optical coherence tomograph — Solix (Optovue Inc., USA)). Endothelial cell density (ECD) remained stable throughout the entire observation period (2327 ± 121 cells / mm²) (endothelial microscope Topcon SP-1P).
Conclusion. Repeated crosslinking is an effective and safe method for stabilizing progressive keratoconus, providing a long-term refractive effect and preserving the morphofunctional parameters of the cornea.

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