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Cynthia J Roberts, Kimberly M Metzler, Ashraf M Mahmoud, Jun Liu; Biomechanical Evaluation of Response to Treatment with Human Decorin Core Protein in Ex-Vivo Human and Porcine Corneas. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1104.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate changes in corneal biomechanical responses after crosslinking with decorin core protein. Decorin is a small, naturally occurring proteoglycan that bridges collagen fibrils, organizing and stabilizing lamellar collagen architecture.
A paired eye study design was utilized to investigate corneal biomechanical changes in 5 human donor pairs (10 eyes) and in 4 porcine pairs (8 eyes) after one random eye was treated (tx) with human decorin core protein (Galacorin), and the untreated fellow eye served as control (c). Epithelium remained intact in all eyes. An eye cup was used for instillation of pretreatment (45-60 sec), followed by the penetration enhancer (45-60sec), followed immediately by decorin core protein (45-60sec) with rinsing in between the last 2 steps. Total treatment time was less than 4 minutes per eye. Human eyes were secured in a custom tripod mount and dynamic Scheimpflug deformation analysis was performed using the CorVis ST at 15, 20, 30, 40, and 50mmHg of intraocular pressure (IOP). Elastic modulus (E) of the cornea was calculated at each pressure level in the human eyes, using equations of applanation and parameters derived from Scheimpflug images. ANOVA was performed with independent variables of treatment and IOP. Porcine corneas were investigated using uniaxial tensile testing with a Rheometrics Systems Analyzer. Paired t tests were then performed.
One human eye pair was excluded based on initial pachymetry greater than 850µm. ANOVA of the included 4 pairs demonstrated a significant treatment effect (p < 0.05) in deformation amplitude, 1st applanation velocity, initial curvature, and pachymetry, with all lower in the Tx group, consistent with stiffening and crosslinking. E demonstrated a significant treatment effect with a higher E in the Tx group. A significant IOP effect was present in most deformation parameters, as well as E, and the interaction term was not significant in any parameter. In porcine eye pairs, secant modulus at both 5% (tx: 1.71± 1.20MPa; c: .85±.62MPa) and 6% (tx: 2.30 ±1.33MPa; c: 1.33±.88MPa) strain was significantly higher in the treated than the untreated corneas (p < 0.05).
Treatment with decorin core protein appeared to produce higher modulus and stiffer biomechanical behavior in both human and porcine corneas. This result will be confirmed in future studies with a larger sample size.
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