Flexure of thin rigid contact lenses
The flexure of spherical rigid contact lenses was measured on the eyes of lO young subjects using a videokeratoscope. Five subjects had little or no with-the-rule astigmatism (< O. 75 D) and five had moderate levels of with-the-rule astigmatism (1.00-2.00 D). Two lens materials (polymethylmethacrylate [PMMA] and Boston XO) in three centre thicknesses (0.05, O. 10 and O. 15 mm) were used in the study. No significant difference in the amount of flexure was found between the two materials tested. The degree of regular astigmatism on the lens front surface was found to increase as the centre thickness of the contact lens decreased. For the astigmatic group, the lenses with centre thicknesses of O.05 mm had levels of front surface astigmatism similar to those of the underlying cornea. On spherical corneas the level of regular astigmatism can exceed that of the cornea for thinner lenses. When sphero-cylinder variations are accounted for, residual higher-order aberration (root mean square) levels were found to approach those of the cornea when the lens thickness was reduced to 0.05 mm.
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|Item Type:||Journal Article|
|Additional Information:||For more information, please refer to the journal’s website (see hypertext link) or contact the author. Michael Collins, email: email@example.com,.au|
|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 2001 Elsevier|
|Deposited On:||24 Mar 2005 00:00|
|Last Modified:||10 Aug 2011 14:09|
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