A study of piezoelectric and mechanical anisotropies of the human cornea

The piezoelectric and dynamic mechanical properties of human cornea have been investigated as a function of drying time. As expected, the piezoelectric coefficient, d(31), and the Young's modulus, Y, were found to be extremely sensitive to water content. d(31) decreased with dehydration of the corneal tissue and Y increased with dehydration. While these results are significant, the discovery of the unprecedented mechanical and electromechanical anisotropy exhibited by the cornea are the major findings of this study and indicate that the collagen fibrils comprising the cornea are highly oriented. The piezoelectric responses of corneas observed in this study are: diagonally cut samples starting at an average piezoelectric coefficient value of 2250 pC/N, followed by the vertically cut samples, with an average starting value of about 600 pC/N and finally the horizontally cut samples with an average starting value of about 200 pC/N.