Inefficacy of aspheric soft contact lenses for the correction of low levels of astigmatism

Morgan, Philip B., Efron, Suzanne E., Efron, Nathan, & Hill, Elizabeth A. (2005) Inefficacy of aspheric soft contact lenses for the correction of low levels of astigmatism. Optometry And Vision Science, 82(9), pp. 823-828.

Abstract

PURPOSE: The purpose of this article is to compare the visual performance of a toric soft (TS) contact lens (SofLens 66 Toric; Bausch & Lomb, Rochester, NY), an aspheric soft (AS) contact lens (Frequency Aspheric; CooperVision, Fairport, NY) and a spectacle correction (SC) in subjects with low levels of astigmatism. METHODS: One eye of 30 subjects with refractive astigmatism of -0.75 DC or -1.00 DC was tested. After pupil dilation, each subject was fitted with all three forms of correction in random order. Subjects were masked from the contact lens type. High-contrast visual acuity (HCVA) and low-contrast visual acuity (LCVA) were recorded for each correction using 2-mm, 4-mm, and 6-mm artificial pupils. RESULTS: With a 2-mm pupil, HCVA was similar for the TS lens and the SC (p = 0.13); better HCVA was demonstrated with the TS lens than with the AS lens (p = 0.001). With 4-mm and 6-mm pupils, HCVA was poorer with the AS lens than with the SC (p < 0.002) and TS lenses (p < 0.0001). The difference in HCVA between the TS and AS lenses was two letters, three letters, and one line with pupil sizes of 2 mm, 4 mm, and 6 mm, respectively. LCVA was similar for the three refractive conditions with the 2-mm pupil size. With 4-mm and 6-mm pupils, LCVA was similar for the TS lens and SC, but better than the AS lens by approximately one line in each case (all p < 0.0001). CONCLUSIONS: For small pupil sizes, there is little difference in HCVA and LCVA between various refractive corrections. However, for larger pupils, HCVA and LCVA are superior with TS contact lenses and SC versus AS contact lenses by approximately a half-line or more, which is considered to be clinically significant. Superior vision can be achieved for low astigmatic contact lens wearers using TS rather than AS contact lenses.

Impact and interest:

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ID Code: 11066
Item Type: Journal Article
Refereed: Yes
Additional Information: The contents of this journal can be freely accessed online via the journal's web page (see hypertext link) 12 months after publication. Self-archiving of the author-version is not yet supported by this publisher.
For more information, please refer to the journal's website (see hypertext link) or contact the author.
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Keywords: aspheric soft contact lens, spherical soft contact lens, high, contrast visual acuity, low, contrast visual acuity, pupil size, aberrations
ISSN: 1040-5488
Subjects: Australian and New Zealand Standard Research Classification > MEDICAL AND HEALTH SCIENCES (110000) > OPTOMETRY AND OPHTHALMOLOGY (111300)
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 2005 Lippincott Williams & Wilkins
Deposited On: 28 Nov 2007 00:00
Last Modified: 29 Feb 2012 13:29

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