Dry physical crosslinking of porcine corneal grafts. In vitro study

Abstract

AbstractPurpose(1) To compare the effects of wet and dry crosslinking (CL) on swell‐resistance of porcine corneal grafts; (2) for grafts obtained by dry physical CL methods, to evaluate some of their surgically relevant properties.MethodsExperiment 1. The cornea was cut out of a frozen porcine eyeball with epithelium and Descemet's membrane removed. 30 such grafts were distributed into 10 groups of treatment (3 per group): five groups of wet grafts (wet control; Riboflavin/ultraviolet‐A CL at doses 5.4 and 54 J/cm2; glutaraldehyde CL at concentrations 0.1 and 1%) and five groups of air‐dried grafts (dry control; ultraviolet‐C (UVC) at doses of 5.4 and 54 J/cm2; dehydrothermal (DHT) CL at 80 and 105 °C). All grafts were immersed in distilled water for 24h, then their light transmission and swelling ratio were measured.Experiment 2. 18 grafts (6 groups: wet non‐hydrated control; wet control; dry control; UVC 54 J/cm2; DHT 105°C; DHT 105°C + UVC 54 J/cm2) were immersed in water for 24 hr, then distant visual quality at 5 m, central thickness (CT) and suture retention strength (SRS) were tested. ANOVA and post‐hoc Tukey HSD tests were used.ResultsExp. 1. There was a significant difference in water content and light transmission between all groups at 24h hydration (p < 0.05, ANOVA). DHT 105°C grafts had significantly lower water content and the highest light transmission in comparison to all other groups (p < 0.05 for each comparison, Tukey HSD).Exp. 2. At 24 hr hydration, DHT+UVC treated grafts allowed distinguishing optotypes 0.4–0.6 (decimal). CT varied from 600 to 1200 microns for DHT+UVC and UVC groups, respectively. Control grafts swelled up to 6000 microns in the center. SRS of all grafts was significantly higher than the strength of the Nylon 9‐0 thread (p<0.05, Tukey HSD).ConclusionsDry physical CL methods allow obtaining corneal grafts with increased swell‐resistance compared to wet CL methods, while maintaining the strength sufficient for their surgical fixation.