title: Mechanical models of the dynamics of vitreous substitutes.
abstract: We discuss some aspects of the fluid dynamics of vitreous substitutes in the vitreous chamber, focussing on the flow induced by rotations of the eye bulb. We use simple, yet not trivial, theoretical models to highlight mechanical concepts that are relevant to understand the dynamics of vitreous substitutes and also to identify ideal properties for vitreous replacement fluids. We first recall results by previous authors, showing that the maximum shear stress on the retina grows with increasing viscosity of the fluid up to a saturation value. We then investigate how the wall shear stress changes if a thin layer of aqueous humour is present in the vitreous chamber, separating the retina from the vitreous replacement fluid. The theoretical predictions show that the existence of a thin layer of aqueous is sufficient to substantially decrease the shear stress on the retina. We finally discuss a theoretical model that predicts the stability conditions of the interface between the aqueous and a vitreous substitute. We discuss the implications of this model to understand the mechanisms leading to the formation of emulsion in the vitreous chamber, showing that instability of the interface is possible in a range of parameters relevant for the human eye.
authors.affiliation: Department of Civil, Chemical and Environmental Engineering, University of Genoa, 16145 Genoa, Italy.
authors.forename: Krystyna
authors.identifier: 0000-0002-6382-9786
authors.initials: K
authors.lastname: Isakova
authors.affiliation: Department of Civil, Chemical and Environmental Engineering, University of Genoa, 16145 Genoa, Italy.
authors.forename: Jan O
authors.initials: JO
authors.lastname: Pralits
authors.affiliation: Department of Civil, Chemical and Environmental Engineering, University of Genoa, 16145 Genoa, Italy.
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Repetto
authors.affiliation: Department of Neuroscience, University of Naples Federico II, 80131 Naples, Italy ; Humanitas Clinical and Research Center, 20089 Milan, Italy.
authors.forename: Mario R
authors.initials: MR
authors.lastname: Romano
mesh_terms: D001082:Aqueous Humor / Q000502:physiology; D057446:Hydrodynamics; D008954:Models, Biological; D012160:Retina / Q000502:physiology*; D033081:Shear Strength / Q000502:physiology; D013314:Stress, Mechanical; D014783:Viscosity; D014822:Vitreous Body / Q000502:physiology*