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Rodolfo Repetto, Federica Di Michele, Amabile Tatone; A mathematical model of posterior vitreous detachment and generation of vitreoretinal tractions. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1595.
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© ARVO (1962-2015); The Authors (2016-present)
Posterior vitreous detachment (PVD) can lead to strong tractions on the retina that are the most common cause of non-traumatic retinal tearing. We propose a mathematical model of the generation of retinal tractions induced by vitreous contraction, which is aimed at understanding the mechanics of the process.
The vitreous humor is modeled as a soft solid surrounded by a membrane that initially fills a spherical domain with rigid walls. We assume that the maximum adhesive force per unit surface between the membrane and the wall can be variable in space, which allows us to simulate cases of focal adhesions. We assume that the relaxed configuration of the solid progressively shrinks in time and, owing to the non uniformity of the adhesive force, this generates detachment of the vitreous from certain regions of the boundary and localized tractions.
In Figure 1(a,b) we show two examples of predicted configurations of the vitreous attained during the progression of the PVD. In (a) we show a “complete vitreous detachment”, in which detachment progressively proceeds from the back (right) towards the front (left) of the vitreous chamber. In (b) we show the case of a PVD in the presence of a focal vitreoretinal adhesion. In this case the model predicts that the vitreous deforms substantially during the contraction process, thus also generating large stresses.
The model can be used to identify shapes of the detaching vitreous that are likely to be associated with large tractions on the boundary and to the existence of particularly strong focal adhesions on the retina, which are risk factors for the generation of retinal tears.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Two examples of the shape taken by the contracting vitreous during PVD, as predicted by the model. (a) Complete PVD, (b) case in which there is a focal adhesion at the back of the vitreous chamber.
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