A MODEL FOR THE FLUID MOTION OF VITREOUS-HUMOR OF THE HUMAN EYE DURING SACCADIC MOVEMENT

During saccadic motion the eyewall moves in a manner similar to a sinu soid or at least can be represented by a sine Fourier series. Motion o f the vitreous is induced by the saccade and the vitreo-retinal interf ace is subjected to a time-dependent shear. This force may be a signif icant factor for retinal tearing in the neighbourhood of small retinal holes or tears. An analytical viscoelastic model and a numerical, New tonian model of the motion of the vitreous are presented and compared. Under sinusoidal boundary motion the analytical model shows that a vi scous wave propagates inward toward the axis of rotation and the chara cteristic length of this wave is a function of the Womersley number. T he numerical solution indicates that the vitreous moves similarly to t he analytical result with small secondary motion; however, this motion allows complete recirculation of the vitreous over large timescales. Excellent agreement is found between the analytical and numerical mode ls. The time-dependent fluid shear is evaluated and from the analytica l solution the maximum value of this is found to be proportional to R( 0)root nu omega(3), where Ro is the eye radius, v the modified complex visocosity and omega the sinusoidal frequency. This indicates that my opes have a larger shear force exerted on them by virtue of the larger eye size. Further work is directed toward a model which links the str ess found in the sclera to that exerted on the vitreo-retinal interfac e by the vitreous fluid motion.