Using corneal oxygen demand to optimize rigid contact lens design
To evaluate the effects of base curve radius, overall diameter, and axial edge lift on rigid contact lens tear pump efficiency, corneal oxygen uptake rates were measured on six eyes under three conditions: normal open eye, after 5 min of static (without blinking) wear, and after 5 min of dynamic (with blinking once every 5 s) wear. The three parameters were varied one at a time from a standard lens design. Differences in corneal oxygen demands between the static and dynamic rates provided quantitative measures of the tear pump efficiency for each lens design. Tear exchange was found to be most sensitively related to changes in base curve radius, followed by overall diameter changes (66.9% as effective) and axial edge lift changes (64.6% as effective). Design equivalencies (to produce identical tear exchange to a 0.05-mm flattening of base curve toward alignment) were 0.07-mm steepening of the base curve toward alignment, 0.35-mm decrease in overall diameter, or 0.037-mm increase in axial edge lift.
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|Item Type:||Journal Article|
|Keywords:||Contact Lenses, Cornea/, metabolism, Oxygen Consumption/, physiology, Adult, Blinking/physiology, Female, Humans, Male, Microelectrodes, Polarography, Prosthesis Design, Tears/metabolism|
|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 1993 American Academy of Optometry|
|Copyright Statement:||Reproduced in accordance with the copyright policy of the publisher.|
|Deposited On:||13 Jul 2006|
|Last Modified:||09 Jun 2010 22:29|
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