Ex Vivo Transepithelial Collagen Cross-linking in Porcine and Human Corneas Using Human Decorin Core Protein

To investigate changes in corneal biomechanics after cross-linking with human decorin core protein (decoron), which is a small, naturally occurring proteoglycan that bridges collagen fibrils, organizing and stabilizing lamellar collagen architecture.

Five human donor pairs (10 eyes) and 5 porcine pairs (10 eyes) had one random eye treated transepithelially with decoron, with the untreated fellow eye serving as control. Pretreatment (45 to 60 seconds) and penetration enhancer (45 to 60 seconds) preceded instillation of decoron (45 to 60 seconds). Total treatment time was less than 4 minutes per eye. Human donor eyes were evaluated using the CorVis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) at 15, 20, 30, 40, and 50 mm Hg of intraocular pressure. Elastic modulus was calculated for human corneas, using parameters derived from Scheimpflug images. Analysis of variance was performed. Porcine corneas underwent uniaxial tensile testing with a Rheometrics Systems Analyzer (RSA III; TA Instruments, New Castle, DE). Secant modulus was calculated and paired t tests were performed between treated and control groups.

One human eye pair was excluded based on initial corneal thickness greater than 850 µm. Analysis of variance of the included four pairs demonstrated a significant treatment effect (P < .05) in deformation amplitude, first applanation velocity, initial curvature, and pachymetry, with all lower in the treatment group, consistent with stiffening and cross-linking. Elastic modulus demonstrated a significant treatment effect with a higher elastic modulus in the treatment group. In porcine eye pairs, the secant modulus was significantly higher in the treated than the untreated corneas at 4%, 5%, and 6% strain (P < .05).

Treatment with decorin core protein produced stiffer biomechanical behavior and higher elastic modulus in both human and porcine corneas in this preliminary ex vivo study. Further studies are needed to evaluate clinical safety, efficacy, and long-term stability. [J Refract Surg. 2016;32(6):410-417.].