HOLOGRAPHIC MEASUREMENT OF CHANGES OF THE CENTRAL CORNEAL CURVATURE DUE TO INTRAOCULAR-PRESSURE DIFFERENCES

Double-exposure as well as real-time holographic interferometry are used to evaluate changes of the central curvature of the bovine cornea in vitro under small intraocular pressure differences. Double-exposure holographic interferograms of expanding corneas were used to get the positions of dark interference fringes on the surface of the cornea. Real-time holographic interferometry enables determining the absolute value of the displacement of the corneal center along the axis of the eye or the number of the fringe that is located closest to the corneal center. A mathematical model is given for the radial distensions and displacement of the center of curvature in two mutually perpendicular planes of a longitudinal section of the cornea along the axis of the eye. Examples of holographic interferograms of a bovine cornea recorded at an intraocular pressure of 1340 Pa and pressure differences of 10 and 20 Pa, respectively, as well as resulting changes of the corneal curvature are presented.