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A comparision of the effects of rigid contact lens overall diameter and axial edge lift changes on tear pump efficiency

Fink, Barbara A. & Carney, Leo G. (1991) A comparision of the effects of rigid contact lens overall diameter and axial edge lift changes on tear pump efficiency. International Contact Lens Clinic, 18, pp. 148-153.

Abstract

Corneal oxygen uptake was used to compare the effects of changes in lens overall and optic-zone diameter to changes in lens axial edge lift on tear pump efficiency. Measurements were made on the right cornea of six human subjects under three conditions; (1) normal open eye, (2) after 5 minutes of static (without blinking) wear of a poly(methyl methacrylate) (non-gas permeable) contact lens, and (3) after 5 minutes of dynamic (with blinking once every 5 seconds) wear of the same lens. The differences between the oxygen uptake rates measured under static and dynamic conditions for a given lens design provided an index of the tear pump efficiency for that design. Two sets of five lenses were worn by each subject. In the first set, lens overall diameter varied from 8.2 to 9.4 mm in 0.3 mm steps, with the optic-zone diameter being 1.4 mm smaller. All other parameters were constant, including a 0.09 mm axial edge lift. In the second set of lenses, axial edge lift varied from 0.05 to 0.13 mm in 0.02mm steps; overall diameter was 8.8 mm, optic, zone diameter was 7.4 mm, and all other parameters were the same as those in Set 1. Tear pump efficiency was greatest for small lenses and for lenses with large axial edge lifts. A 0.3 mm decrease in overall diameter was approximately equivalent to a 0.03 mm increase in axial edge lift as a means of enhancing tear pump efficiency.

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ID Code: 3153
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: l.carney@qut.edu.au
Additional URLs:
Keywords: Contact lens, overall diameter, axial edge lift, tear pump efficiency
ISSN: 0892-8967
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 1991 Elsevier
Deposited On: 30 Jan 2006
Last Modified: 15 Jan 2009 16:54

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