QUT ePrints

Field restriction and vignetting in contact lenses with opaque peripheries

Carkeet, Andrew D. (1998) Field restriction and vignetting in contact lenses with opaque peripheries. Clinical and Experimental Optometry, 81(4), pp. 151-158.

Abstract

Background: Some previous researchers have shown empirically that visual fields can be restricted by contact lenses with opaque and semi-opaque peripheral zones. However, there has been no formal statement of the optical theory behind such restriction.

Methods: Calculations are made of fields of view with opaque periphery contact lenses, based on paraxial theory and meridional finite ray tracing in the Gullstrand-Emsley schematic eye.

Results: This analysis shows that paraxial theory is adequate for predicting 'half fields of full illumination' for ocular pupil diameters smaller than six millimetres, although paraxial estimates of ‘half total field’ can substantially underestimate those obtained by finite ray tracing for a wide range of ocular pupil sizes. Therefore finite ray tracing may be a more appropriate method of calculating half total field. 'Total field' will be smaller with smaller ocular pupils and smaller contact lens apertures. A clinical method is suggested for assessing total field with such contact lenses in situ. The analysis applied to opaque periphery contact lenses is extended to the semi-opaque periphery contact lenses used for cosmetic alteration of eye appearance.

Conclusion: Semi-opaque periphery contact lenses will decrease retinal illuminance most at regions outside those tested by previous empirical static perimetry studies.

Impact and interest:

Citation countsare sourced monthly from Scopus and Web of Science® citation databases.

These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.

Citations counts from the Google Scholar™ indexing service can be viewed at the linked Google Scholar™ search.

ID Code: 11868
Item Type: Journal Article
Additional Information: For more information, please refer to the journal's website (see hypertext link) or contact the author.
Additional URLs:
Keywords: opaque contact lenses, optics, vignetting, visual fields
ISSN: 0816-4622
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300) > Optical Technology (111302)
Divisions: Current > Research Centres > Centre for Health Research
Current > QUT Faculties and Divisions > Faculty of Health
Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 1998 Blackwell Publishing
Deposited On: 14 Jan 2008
Last Modified: 22 Apr 2010 02:27

Export: EndNote | Dublin Core | BibTeX

Repository Staff Only: item control page