Influence of rigid contact lens base curve radius on tear pump efficiency
The effects of rigid contact lens base curve radius changes on tear pump efficiency were determined by measuring oxygen uptake on six with-the-rule corneas (with toricities between 0.37 and 1.00 D) under three conditions: (1) normal open eye, (2) after 5 min of static (without blinking) wear of polymethyl methacrylate (non-gas permeable) contact lenses, and (3) after 5 min of dynamic (with blinking once every 5 s) wear of the same lenses. The difference between the oxygen uptake rates measured under static and dynamic conditions provides an index of tear pump efficiency. Each subject wore a series of five lenses: fitted on K and 0.05 or 0.10 mm steeper and flatter than the flattest corneal meridian. The overall diameter of all lenses was 8.8 mm, the optic zone was 7.4 mm, the axial edge lift was 0.09 mm, and all other parameters were constant. The contact lens fitted on K was associated with the greatest central corneal oxygen debt under static conditions, whereas the same lens also provided for the best tear exchange with the blink. In addition, better tear exchange was found to be associated with larger palpebral aperture sizes.
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|Item Type:||Journal Article|
|Keywords:||Contact Lenses, Cornea/, physiology, Tears/, physiology, Adult, Blinking, Female, Humans, Male, Methylmethacrylate, Methylmethacrylates, Microelectrodes, Oxygen Consumption, Polarography|
|Subjects:||Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > PAEDIATRICS AND REPRODUCTIVE MEDICINE (111400) > Paediatrics (111403)
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 1992 American Academy of Optometry|
|Copyright Statement:||Reproduced in accordance with the copyright policy of the publisher.|
|Deposited On:||13 Jul 2006 00:00|
|Last Modified:||09 Jun 2010 12:29|
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