MEASUREMENT OF ELASTIC-MODULUS OF THE CENTRAL BOVINE CORNEA BY MEANS OF HOLOGRAPHIC-INTERFEROMETRY .2. RESULTS

Background. The structural and elastic properties of the cornea play a n important role in the outcome of corneal refractive surgery. A way t o describe the elastic properties is to calculate Young's modulus. The tangent Young's modulus (E(it)) represents the first part of the visc oelastic response of the intact cornea due to intraocular pressure inc rease. Method. The tangent Young's modulus (E(it)) of the central corn ea of 16 fresh enucleated intact bovine eyes determined from the immed iate response was calculated by means of holographic interferometry. T he stress was an increase of the intraocular pressure. In 16 eyes the change of intraocular pressure was 10 Pa (group I), starting with an i ntraocular pressure of 1340 Pa (about 10 mm Hg). In 6 of these 16 eyes there was a second pressure increase of 20 Pa starting at the same in traocular pressure of 1340 Pa (about 10 mm Hg) (group II). Results. Th e mean value for the Young's modulus in group I was 1.58 x 10(5) Pa. F or group II the Young's modulus was 1.60 x 10(5) Pa. The difference wa s not significant. The values for the Young's moduli of the cornea of intact eyes are about 100 times smaller than calculations based on exp eriments with strips of the cornea. Conclusion. It is necessary to con sider the localization of the corneal tissue to avoid influences of co rneal hydration or dehydration and to define the existing intraocular pressure if Young's modulus of the cornea is to be calculated.