Effects of storage and wound healing on corneal biomechanics

Material testing techniques were used to characterize the mechanical properties of corneal tissue and to observe the effects of corneal storage and growth factors on these properties. Uniaxial stress-relaxation tests were performed on fresh and stored rabbit corneas. Fresh corneas recovered an average of 37.7% of first-pull stress while those stored in MK solution recovered an average of 76%. Stress-relaxation time constants were also found to be significantly different. Uniaxial tensile tests of fresh monkey corneas were performed to evaluate wound strengths of penetrating incisions treated with platelet derived growth factor (PDGF). Treated wounds demonstrated a greater failure strength than untreated wounds, indicating that corneal healing is enhanced in the presence of PDGF. Mechanical testing of corneal tissue is thus shown to be a useful technique for investigating changes in corneal structure.