Experimental ex vivo Study of Femtosecond-assisted Radial Keratotomy (Femto LDV Z8) in Progressive Keratoconus

Purpose: To assess the technical feasibility and quality of femtosecond radial keratotomy using the Femto LDV Z8 laser system, as well as to determine the biomechanical strength of the cornea under static load in ex vivo experiments.

Material and methods. The study was conducted on cadaveric eyes using the Ziemer Femto LDV Z8 laser system (Switzerland). Individual patterns for dosed corneal incisions were developed, specifically adapted for surgical treatment of progressive keratoconus. Radial incisions were created in the annular zone of the cornea (outer diameter 9–10 mm, inner diameter 3.5–4 mm). Samples were divided into two equal groups: Group 1 (n = 5) — femtosecond radial keratotomy; Group 2 (n = 5) — FS keratotomy followed by ultraviolet corneal collagen crosslinking. To assess the mechanical properties of the cornea, the burst indentation test was used according to GOST 31897 standard, with incremental mechanical loading and fixation of the tissue rupture point. The obtained data enabled comparison of the biomechanical resistance of the cornea after different surgical interventions.

Conclusion. A unique software for the Femto LDV Z8 laser was developed, enabling femtosecond radial keratotomy. The ex vivo results confirmed the technical feasibility of the method and demonstrated that combined intervention (FS-keratotomy followed by UV cross-linking) significantly increases biomechanical strength of the cornea compared to isolated keratotomy, as evidenced by higher rupture load.

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