Effects of defocus and pupil size on human contrast sensitivity

Strang, Niall C., Atchison, David A., & Woods, Russell L. (1999) Effects of defocus and pupil size on human contrast sensitivity. Ophthalmic and Physiological Optics, 19(5), pp. 415-426.

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Defocus lowers the contrast sensitivity function (CSF), producing a complex function with local dips and peaks. Previously, we were able to predict the shape of the CSF with large pupils from measured transverse aberrations with hypermetropic defocus but not with myopic defocus (Atchison et al., 1998c, J. Opt. Soc. Am. A. 15, 2536). As there is no reason that myopic defocus should be more difficult to predict than hypermetropic defocus, we modified the procedure to try to improve CSF predictions with myopic defocus. Also, we extended the study to consider a range of pupil sizes. CSFs were measured for three subjects at three defocus levels (in-focus, -2D and +2D) and three pupil sizes (2 mm, 4 mm and 6 mm). Using a diffraction optics model, transverse aberration measures and in-focus CSF measures, we predicted the defocused CSFs. The predicted defocused CSFs were lower than the in-focus CSF as expected, and had complex shapes that varied with defocus and pupil size and between subjects. While a few predictions were poor, generally, the overall magnitude and shape of the defocused CSFs were well predicted and similarly so for myopic and hypermetropic defocus. Some further improvements in technique are indicated.

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24 citations in Web of Science®
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ID Code: 5176
Item Type: Journal Article
Refereed: Yes
Additional Information: For more information, please refer to the journal’s website (see link) or contact the author. Author contact details: d.atchison@qut.edu.au
Keywords: defocus, pupil size, human, contrast sensitivity
DOI: 10.1046/j.1475-1313.1999.00459.x
ISSN: 0275-5408
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 1999 Blackwell Publishing
Copyright Statement: The definitive version is available at www.blackwell-synergy.com
Deposited On: 09 Oct 2006 00:00
Last Modified: 10 Aug 2011 18:25

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