Speaker
Description
The choroid is a densely vascularised layer of tissue of the eye, lying between the retina and the sclera (outer layer of the eye), which carries the majority of ocular blood flow. Vortex veins
drain blood out of the eye (to the orbit), crossing the sclera from the choroidal circulation.
Animal experiments have shown that pressure in these veins is tightly linked to intraocular pressure (IOP) \cite{1}. Partial collapse of the vortex veins in the sclera has been hypothesised to be responsible for venous pressure control in the choroid \cite{2,3}.
In this work, we formulate a Starling resistor model of a vortex vein, investigating whether it can explain the observed pressure behaviour. We model the vein as a collapsible tube, with a segment within the choroid subjected to IOP, and a segment crossing the sclera in which the
external pressure linearly decreases from IOP to the orbital tissue pressure. In order to fully reproduce the experimental results \cite{2}, we extend the model to account for more than one vortex vein.
We show that, under physiological conditions, the experimentally observed behaviour of the choroidal venous outflow can be reproduced by the model, if the vortex vein is collapsed in the scleral segment. In this case, increasing IOP results in an increase of choroidal venous
pressure of almost the same amount.
In summary, the model suggests a mechanical explanation for passive control of choroidal venous pressure by vortex vein collapse within the sclera.
Co-authors:
- Peter Stewart, School of Mathematics & Statistics, University of Glasgow, Glasgow, UK
- Alexander J. E. Foss, Department of Ophthalmology, Nottingham University Hospitals
NHS Trust, Nottingham, UK
- Jennifer Tweedy, Mathematical Sciences, University of Bath, Bath, UK
- Rodolfo Repetto, Department of Civil, Chemical and Environmental Engineering,
University of Genoa, Genoa, Italy.
Bibliography
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author = {Olav Mäepea},
doi = {10.1016/0014-4835(92)90028-Q},
issn = {00144835},
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journal = {Experimental eye research},
pages = {731-736},
pmid = {1623958},
publisher = {Exp Eye Res},
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url = {https://pubmed.ncbi.nlm.nih.gov/1623958/},
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}
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issn = {00144835},
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pages = {193-199},
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publisher = {Exp Eye Res},
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volume = {1},
url = {https://pubmed.ncbi.nlm.nih.gov/13869182/},
year = {1962},
}
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