INSTITUTE OF PHYSICS PUBLISHING PHYSICS IN MEDICINE AND BIOLOGY Phys. Med. Biol. 50 (2005) 4729–4743 doi:10.1088/0031-9155/50/19/021 Experimental investigation of vitreous humour motion within a human eye model Rodolfo Repetto 1 , Alessandro Stocchino 2 and Chiara Cafferata 2 1 Dipartimento di Ingegneria delle Strutture, delle Acque e del Terreno, University of L’Aquila, Italy 2 Dipartimento di Ingegneria Ambientale, University of Genova, Italy E-mail: rodolfo@ing.univaq.it Received 7 June 2005, in final form 1 August 2005 Published 21 September 2005 Online at stacks.iop.org/PMB/50/4729 Abstract We present an experimental study of the vitreous motion induced by saccadic eye movements. A magnified model of the vitreous chamber has been employed, consisting of a spherical cavity carved in a perspex cylindrical container, which is able to rotate with a prescribed time law. Care has been taken to correctly reproduce real saccadic eye movements. The spherical cavity is filled with glycerol and the flow field is measured on the equatorial plane orthogonal to the axis of rotation, through the PIV technique. Visualizations of the fully three-dimensional flow suggest that it essentially occurs on planes perpendicular to the axis of rotation, the motion orthogonal to such planes being smaller by three to four orders of magnitude. Theoretical results, based on a simplified solution, are in very good agreement with the experimental findings. The maximum value of the shear stress at the wall, which is thought to play a possibly important role in the pathogenesis of retinal detachment, does not significantly depend on the amplitude of saccadic movements. This suggests that relatively small eye rotations, being much more frequent than large movements, are mainly responsible for vitreous stresses on the retina. Results also illustrate the dependence of the maximum shear stress at the wall from the vitreous viscosity. 1. Introduction The vitreous humour, which is bounded between the lens and the retina, is the substance filling the vitreous chamber of the human eye. Lee et al (1992) have studied the rheology of vitreous, showing that, in normal conditions, it behaves as a viscoelastic material. However, typically, with advancing age the vitreous partially or completely loses its elastic properties, as a consequence of a ‘liquefaction process’. 0031-9155/05/194729+15$30.00 © 2005 IOP Publishing Ltd Printed in the UK 4729