title: An experimental model of vitreous motion induced by eye rotations.
abstract: BACKGROUND
  During eye rotations the vitreous humour moves with respect to the eye globe. This relative motion has been suggested to possibly have an important role in inducing degradation of the gel structure, which might lead to vitreous liquefaction and/or posterior vitreous detachment. Aim of the present work is to study the characteristics of vitreous motion induced by eye rotations.
  
  
  METHODS
  We use an experimental setup, consisting of a Perspex model of the vitreous chamber that, for simplicity, is taken to have a spherical shape. The model is filled with an artificial vitreous humour, prepared as a solution of agar powder and hyaluronic acid sodium salt in deionised water, which has viscoelastic mechanical properties similar to those of the real vitreous. The model rotates about an axis passing through the centre of the sphere and velocity measurements are taken on the equatorial plane orthogonal to the axis of rotation, using an optical technique.
  
  
  RESULTS
  The results show that fluid viscoelasticity has a strong influence on flow characteristics. In particular, at certain frequencies of oscillation of the eye model, fluid motion can be resonantly excited. This means that fluid velocity within the domain can be significantly larger than that of the wall.
  
  
  CONCLUSIONS
  The frequencies for which resonant excitation occurs are within the range of possible eye rotations frequencies. Therefore, the present results suggest that resonant excitation of vitreous motion is likely to occur in practice. This, in turn, implies that eye rotations produce large stresses on the retina and within the vitreous that may contribute to the disruption of the vitreous gel structure. The present results also have implications for the choice of the ideal properties for vitreous substitute fluids.
authors.affiliation: Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Bonfiglio
authors.affiliation: Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Lagazzo
authors.affiliation: Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Repetto
authors.affiliation: Department of Civil, Chemical and Environmental Engineering, University of Genoa, Italy, Via Montallegro 1, Genoa, 16145 Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Stocchino
keywords: Retinal detachment; Viscoelasticity; Vitreous dynamics; Vitreous motion