A mass and solute balance model for tear volume and osmolarity in the normal and the dry eye

Handle URI:
http://hdl.handle.net/10754/597298
Title:
A mass and solute balance model for tear volume and osmolarity in the normal and the dry eye
Authors:
Gaffney, E.A.; Tiffany, J.M.; Yokoi, N.; Bron, A.J.
Abstract:
Tear hyperosmolarity is thought to play a key role in the mechanism of dry eye, a common symptomatic condition accompanied by visual disturbance, tear film instability, inflammation and damage to the ocular surface. We have constructed a model for the mass and solute balance of the tears, with parameter estimation based on extensive data from the literature which permits the influence of tear evaporation, lacrimal flux and blink rate on tear osmolarity to be explored. In particular the nature of compensatory events has been estimated in aqueous-deficient (ADDE) and evaporative (EDE) dry eye. The model reproduces observed osmolarities of the tear meniscus for the healthy eye and predicts a higher concentration in the tear film than meniscus in normal and dry eye states. The differential is small in the normal eye, but is significantly increased in dry eye, especially for the simultaneous presence of high meniscus concentration and low meniscus radius. This may influence the interpretation of osmolarity values obtained from meniscus samples since they need not fully reflect potential damage to the ocular surface caused by tear film hyperosmolarity. Interrogation of the model suggests that increases in blink rate may play a limited role in compensating for a rise in tear osmolarity in ADDE but that an increase in lacrimal flux, together with an increase in blink rate, may delay the development of hyperosmolarity in EDE. Nonetheless, it is predicted that tear osmolarity may rise to much higher levels in EDE than ADDE before the onset of tear film breakup, in the absence of events at the ocular surface which would independently compromise tear film stability. Differences in the predicted responses of the pre-ocular tears in ADDE compared to EDE or hybrid disease to defined conditions suggest that no single, empirically-accessible variable can act as a surrogate for tear film concentration and the potential for ocular surface damage. This emphasises the need to measure and integrate multiple diagnostic indicators to determine outcomes and prognosis. Modelling predictions in addition show that further studies concerning the possibility of a high lacrimal flux phenotype in EDE are likely to be profitable. © 2009 Elsevier Ltd. All rights reserved.
Citation:
Gaffney EA, Tiffany JM, Yokoi N, Bron AJ (2010) A mass and solute balance model for tear volume and osmolarity in the normal and the dry eye. Progress in Retinal and Eye Research 29: 59–78. Available: http://dx.doi.org/10.1016/j.preteyeres.2009.11.002.
Publisher:
Elsevier BV
Journal:
Progress in Retinal and Eye Research
KAUST Grant Number:
KUK-C1-013-04
Issue Date:
Jan-2010
DOI:
10.1016/j.preteyeres.2009.11.002
PubMed ID:
19944776
Type:
Article
ISSN:
1350-9462
Sponsors:
We are extremely grateful to Professor Caroline Begley for insightful discussions and for making her work available to us (Liu et al., 2009) prior to publication. This publication is based on work supported in part by Award No. KUK-C1-013-04, made by King Abdullah University of Science and Technology (KAUST).
Appears in Collections:
Publications Acknowledging KAUST Support

Full metadata record

DC FieldValue Language
dc.contributor.authorGaffney, E.A.en
dc.contributor.authorTiffany, J.M.en
dc.contributor.authorYokoi, N.en
dc.contributor.authorBron, A.J.en
dc.date.accessioned2016-02-25T12:30:08Zen
dc.date.available2016-02-25T12:30:08Zen
dc.date.issued2010-01en
dc.identifier.citationGaffney EA, Tiffany JM, Yokoi N, Bron AJ (2010) A mass and solute balance model for tear volume and osmolarity in the normal and the dry eye. Progress in Retinal and Eye Research 29: 59–78. Available: http://dx.doi.org/10.1016/j.preteyeres.2009.11.002.en
dc.identifier.issn1350-9462en
dc.identifier.pmid19944776en
dc.identifier.doi10.1016/j.preteyeres.2009.11.002en
dc.identifier.urihttp://hdl.handle.net/10754/597298en
dc.description.abstractTear hyperosmolarity is thought to play a key role in the mechanism of dry eye, a common symptomatic condition accompanied by visual disturbance, tear film instability, inflammation and damage to the ocular surface. We have constructed a model for the mass and solute balance of the tears, with parameter estimation based on extensive data from the literature which permits the influence of tear evaporation, lacrimal flux and blink rate on tear osmolarity to be explored. In particular the nature of compensatory events has been estimated in aqueous-deficient (ADDE) and evaporative (EDE) dry eye. The model reproduces observed osmolarities of the tear meniscus for the healthy eye and predicts a higher concentration in the tear film than meniscus in normal and dry eye states. The differential is small in the normal eye, but is significantly increased in dry eye, especially for the simultaneous presence of high meniscus concentration and low meniscus radius. This may influence the interpretation of osmolarity values obtained from meniscus samples since they need not fully reflect potential damage to the ocular surface caused by tear film hyperosmolarity. Interrogation of the model suggests that increases in blink rate may play a limited role in compensating for a rise in tear osmolarity in ADDE but that an increase in lacrimal flux, together with an increase in blink rate, may delay the development of hyperosmolarity in EDE. Nonetheless, it is predicted that tear osmolarity may rise to much higher levels in EDE than ADDE before the onset of tear film breakup, in the absence of events at the ocular surface which would independently compromise tear film stability. Differences in the predicted responses of the pre-ocular tears in ADDE compared to EDE or hybrid disease to defined conditions suggest that no single, empirically-accessible variable can act as a surrogate for tear film concentration and the potential for ocular surface damage. This emphasises the need to measure and integrate multiple diagnostic indicators to determine outcomes and prognosis. Modelling predictions in addition show that further studies concerning the possibility of a high lacrimal flux phenotype in EDE are likely to be profitable. © 2009 Elsevier Ltd. All rights reserved.en
dc.description.sponsorshipWe are extremely grateful to Professor Caroline Begley for insightful discussions and for making her work available to us (Liu et al., 2009) prior to publication. This publication is based on work supported in part by Award No. KUK-C1-013-04, made by King Abdullah University of Science and Technology (KAUST).en
dc.publisherElsevier BVen
dc.subjectCompartment modelen
dc.subjectTear filmen
dc.subjectTear hyperosmolarityen
dc.subjectTear osmolarityen
dc.subjectTear volumeen
dc.titleA mass and solute balance model for tear volume and osmolarity in the normal and the dry eyeen
dc.typeArticleen
dc.identifier.journalProgress in Retinal and Eye Researchen
dc.contributor.institutionUniversity of Oxford, Oxford, United Kingdomen
dc.contributor.institutionNuffield Department of Clinical Medicine, Oxford, United Kingdomen
dc.contributor.institutionKyoto Prefectural University of Medicine, Kyoto, Japanen
kaust.grant.numberKUK-C1-013-04en

Related articles on PubMed

All Items in KAUST are protected by copyright, with all rights reserved, unless otherwise indicated.