A comparison of biomechanical properties between human and porcine cornea

Due to the difficulty in obtaining human corneas, pig corneas are often sub stituted as models for cornea research. The purpose of this study is to fin d the similarities and differences in the biomechanical properties between human and porcine corneas. Uniaxial tests were conducted using an Instron a pparatus to determine their tensile strength, stress-strain relationship, a nd stress-relaxation properties. The tensile strength and stress-strain rel ation were very similar but significant differences between the two tissues were observed in the stress-relaxation relationship. Under the same stretc h ratio lambda = 1.5, porcine cornea relaxed much more than human cornea. I f tensile strength and the stress-strain relation are the only mechanical f actors to be investigated, porcine cornea can be used as a substitute model for human cornea research. However, when stress relaxation is a factor, po rcine corneas cannot be used as an appropriate model for human corneas in m echanical property studies. It is very difficult to get enough specimens of human cornea, so we did the experiments for stress-strain relationship at a specific value of strain rate (corresponding to the velocity of loading 1 0 mm/min), and for stress relaxation at a specific stretch ratio lambda = 1 .5. (C) 2001 Elsevier Science Ltd. All rights reserved.