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Reading Group Seminars / Rodolfo REPETTO

Reading Group Seminars

 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,

Rodolfo REPETTO,
Department of Civil, Chemical and Environmental Engineering, University of Genoa

terra' una conferenza dal titolo:
"Aqueous humour flow in the presence of intraocular lenses"

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 on the
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.

03 February 2015
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