Con preghiera di diffusione tra tutti i possibili interessati, scusandomi per invii multipli. Cordialmente, Giacomo Aletti
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Nell'ambito dei Reading Group Seminars e del Seminario di Matematica Applicata, il giorno lunedì 9 Febbraio 2015, alle ore 14.30, nell'Aula C (secondo piano) del Dipartimento di Matematica dell'Universita' degli Studi di Milano, Via C. Saldini, 50, Milano,
"Aqueous humour flow in the presence of intraocular lenses"
Rodolfo REPETTO, Department of Civil, Chemical and Environmental Engineering, University of Genoa
Abstract: Lens placement in the anterior chamber is an increasingly popular method of correcting vision. The lens has a diameter slightly larger than the pupil aperture, and it is placed centrally and just anterior to the iris. The use intraocular lenses is generally very effective and has proven to have good long term clinical outcomes. However, the presence of the lens can lead to possible undesired side effects, including a reduction in endothelial cell density onthe inner corneal surface, which reduces corneal nourishing. Another possible problem is an increase in the resistance to fluid flow between the posterior and anterior chambers of the eye. Aqueous humour is required to flow between these chambers and if the resistance increases sufficiently then pupillary block could occur, meaning the pressure in the posterior chamber increases, which could result in angle closure glaucoma. If the risk is thought to be high the niridotomy is typically used, in which a hole is created in the iris in order to allow flow to by pass the pupil aperture, creating an alternative low-resistance pathway for the aqueous humour. As well as the flow described above, other effects can lead to flow in the anterior chamber. Firstly, there is a temperature gradient between the inner corneal surface and the iris and lens, depending on the difference between atmospheric and body temperature. Combined with gravitational effects, this leads to a buoyancy-driven flow. Secondly, the eye performs saccades, and rotational saccades lead to accelerations and hence flow. In addition, other movements, such as lens movement during accommodation, rubbing the eye, and accidental impacts will lead to flow. In this presentation we show results from a model of flow due to pressure gradient, thermal and saccadic effects in the posterior and anterior chambers in an eye, both with and without the artificial lens in place. We adopt both an analytical approach based on the use of the lubrication theory and a fully numerical model to assess the wall shear stress on the corneal surface, the pressure drop between the posterior and anterior chambers, with the aim of understanding how the positioning of the lens affects these quantities. In the second part of the talk some open issues concerning the fluid mechanics of the eye will also be presented and briefly commented upon.
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Reading Group Seminars: The Reading Group Seminars (RGS) are organized within an open community of researchers interested in applying up to date mathematical modeling and data analysis approaches to the study of biological systems. The RGS take place at the Math. Department in Milan (via Saldini). Initiatives and updates are published on the website: http://rgs.mat.unimi.it/.