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Elastohydrodynamics of the eyelid wiper

Elastohydrodynamics of the eyelid wiper
Elastohydrodynamics of the eyelid wiper
This paper presents an elastohydrodynamic model of the human eyelid wiper. Standard lubrication theory is applied to the fluid layer between the eyelid wiper and ocular surface. The role of the lubrication film is to reduce the shear stresses by preventing solid to solid contact between the eyelid wiper and ocular surface. For the lubrication film to be effective, it is required that the orientation of the eyelid wiper changes between the opening and closing phases of a blink.

In order to model this, the hydrodynamic model is coupled with an elastic mattress model for the soft tissue of the eyelid wiper and ocular surface. This leads to a one-dimensional non-linear partial differential equation governing the fluid pressure in the lubrication film. In order to solve the differential equation, a loading condition or constraint equation must be specified. The resulting system is then solved numerically. The model allows predictions of the tear film flux from under the upper eyelid, as well as normal and shear stresses acting on the ocular surface.

These factors are important in relation to dry eye syndrome, deformation of the cornea and contact lens design. It is found that the pressure and shear stress under the eyelid act across a length of approximately 0.1 mm which is consistent with clinical observations. It order to achieve a flow of tears from under the upper eyelid during a blink, the model requires that the normal force the eyelid applies to the ocular surface during the closing phase of the blink is significantly higher than during the opening phase of the blink.
0092-8240
323-343
Jones, M.B.
42e3c64b-175e-476a-aec7-16186255d452
Fulford, G.R.
9c84a284-75d9-49bf-8df0-b1e0c9d3c61a
Please, C.P.
118dffe7-4b38-4787-a972-9feec535839e
McElwain, D.L.S.
2b1b25a5-d12f-41bd-bf1a-0f8b9afd65b6
Collins, M.J.
7cd1529d-07f6-4313-bff5-0a3e85a61f91
Jones, M.B.
42e3c64b-175e-476a-aec7-16186255d452
Fulford, G.R.
9c84a284-75d9-49bf-8df0-b1e0c9d3c61a
Please, C.P.
118dffe7-4b38-4787-a972-9feec535839e
McElwain, D.L.S.
2b1b25a5-d12f-41bd-bf1a-0f8b9afd65b6
Collins, M.J.
7cd1529d-07f6-4313-bff5-0a3e85a61f91

Jones, M.B., Fulford, G.R., Please, C.P., McElwain, D.L.S. and Collins, M.J. (2008) Elastohydrodynamics of the eyelid wiper. Bulletin of Mathematical Biology, 70 (2), 323-343. (doi:10.1007/s11538-007-9252-7). (PMID:18066629)

Record type: Article

Abstract

This paper presents an elastohydrodynamic model of the human eyelid wiper. Standard lubrication theory is applied to the fluid layer between the eyelid wiper and ocular surface. The role of the lubrication film is to reduce the shear stresses by preventing solid to solid contact between the eyelid wiper and ocular surface. For the lubrication film to be effective, it is required that the orientation of the eyelid wiper changes between the opening and closing phases of a blink.

In order to model this, the hydrodynamic model is coupled with an elastic mattress model for the soft tissue of the eyelid wiper and ocular surface. This leads to a one-dimensional non-linear partial differential equation governing the fluid pressure in the lubrication film. In order to solve the differential equation, a loading condition or constraint equation must be specified. The resulting system is then solved numerically. The model allows predictions of the tear film flux from under the upper eyelid, as well as normal and shear stresses acting on the ocular surface.

These factors are important in relation to dry eye syndrome, deformation of the cornea and contact lens design. It is found that the pressure and shear stress under the eyelid act across a length of approximately 0.1 mm which is consistent with clinical observations. It order to achieve a flow of tears from under the upper eyelid during a blink, the model requires that the normal force the eyelid applies to the ocular surface during the closing phase of the blink is significantly higher than during the opening phase of the blink.

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More information

e-pub ahead of print date: 8 December 2007
Published date: February 2008

Identifiers

Local EPrints ID: 146625
URI: http://eprints.soton.ac.uk/id/eprint/146625
ISSN: 0092-8240
PURE UUID: 679a9c5b-ca7d-486b-b2c7-9eb0699de5ec

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Date deposited: 28 Apr 2010 08:13
Last modified: 14 Mar 2024 00:56

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Contributors

Author: M.B. Jones
Author: G.R. Fulford
Author: C.P. Please
Author: D.L.S. McElwain
Author: M.J. Collins

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