The Influence of Cornea to the Measurement of Three – Dimensional Rotations

Abstract

The mathematical model of corneal optics was developed, which is used for simulation of propagation of the light rays fiber through the cornea. The model was implemented by programming in MATLAB. This model is used for analysis of the corneal influence to form the iris and pupil image. Because of the corneal influence the iris image has nonlinear transformation and it’s distorted. If we want to estimate corneal optics influence to form the iris and pupil image on the plane, the image projection of iris and pupil on the plane we must get from spherical iris (not plane) [6], which radius is 26,2mm. There are bends in iris beams, when corrected iris model is used for simulation of rotations in ±30 degrees diapason. In the limits of the rotation diapason they are 0,6 degree. The change tendencies of the iris and pupil are similar being on iris model without corneal influence [6]. The diagrams of horizontal, vertical and oblique rotations are similar by their form and the change regularity to the diagrams of model without corneal influence [6]. The length and the angle changes by the parabola law. But it makes difference, because changes is asymmetric, when rotations are in the same angles, but in the opposite directions. When eye is making 3D rotation, the form of pupil and iris image become ellipse. We must take into account it, when we calculate the centre co-ordinates of the pupil. If we don’t estimate bends, length and angle changes of the iris beams during 3D rotations, the big errors are possible for estimatation of torsional eye rotations, when we use iris signature correlation method. Ill. 12, bibl. 7 (in English; summaries in Lithuanian, English, Russian).