Crosslinking of the Bioplast plastic material as a means of increasing its biomechanical stability and the effectiveness of keratoplasty for corneal ulcers

Abstract

Purpose:to assess the effect of ultraviolet (UVA) crosslinking of Bioplast plastic material (silicon-dried human cornea) on its biomechanical stability and effectiveness for keratoplasty in corneal ulcers. Material and methods. To determine the maximum rehydration time, 12 Bioplast samples were incubated in physiological solution (NaCl 0.9 %) for 12 hours and monitored for thickness using optical coherence tomography (OCT Spectralis, Heidelberg Engineering). After the epithelium was scarified rehydrated corneas were treated withof 0.1% riboflavin solution for 30 minutes, and after it 8 rehydrated samples (experimental group) were treated with UVA for 30minutes (wavelength 370 nm, power 3 mW/cm2) using a UV-X device system (IROC AG, Switzerland). In the control group (4 rehydrated samples), no UVA crosslinking was performed. The elastic-strength indicators of the experimental and control group samples were assessed by applying uniaxial tension using a deformation machine (Autograph AGS-H, Japan). To examine the patients (presented in clinical examples)before and after keratoplasty with Bioplast subjected to UVA crosslinking, a set of standard ophthalmic tests was used. Results.Rehydration of Bioplast was the most intensive in the first three hours of incubation, during which time tissue thickness increased uniformly by 50–55 μm/hour to 700–710 μm, while further incubation showed no significant additional effect on the fluid content in the cornea. After UVA crosslinking, the strength indices and the elastic modulus of the rehydrated Bioplast samples significantly increased in comparison with the control group. Clinical examples demonstrate the effectiveness of modified Bioplast for organ-preserving penetrating keratoplasty in case of perforatedcorneal ulcer. Conclusion. UVA crosslinking of rehydrated Bioplast increases its biomechanical stability. The data of laboratory studies and the first clinical tests demonstrate that modified Bioplast may be an effective replacement of native donor cornea in urgent keratoplasty of perforated ulcers.