Definitions for hydration changes of hydrogel lenses
Authors of studies on the hydration characteristics of hydrogel lenses have used a variety of definitions to describe the changes observed with exposure of the lenses to different environments. This has resulted in difficulties in the interpretation of published data. In particular, the single term "percentage dehydration" has been used to denote different mathematical expressions for alterations to the lens composition. A detailed theoretical analysis of hydrogel hydration levels is presented to examine definitions for lens hydration changes, compare results obtained under different definitions and propose appropriate usage for the alternative definitions according to the aspect of lens performance under consideration. The interrelationships between the commonly used definitions of dehydration are shown to be independent of initial lens mass but dependent on initial water content. Typically, higher water content lenses undergo considerably larger mass changes than lower water content lenses, an effect that may be masked if these changes are presented as changes of water content. There are a number of clinical consequences of lens dehydration, the importance of which will vary depending on the initial lens water content. It is therefore essential when comparing different water content lenses on the basis of the extent of dehydration to do so with respect to a specific clinical consequence rather than in general terms.
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|Item Type:||Journal Article|
|Additional Information:||For more information, please refer to the journal’s website (see link) or contact the author. Author contact details: email@example.com|
|Keywords:||Contact Lenses, Hydrophilic, Polyethylene Glycols, Terminology, Water/, analysis, Hydrogel, Oxygen, Permeability, Research Support, Non, U, S, Gov't, Time Factors|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)|
|Divisions:||Current > QUT Faculties and Divisions > Faculty of Health|
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 1986 Blackwell Publishing|
|Deposited On:||08 Feb 2006|
|Last Modified:||10 Aug 2011 23:21|
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