Predicting the effects of optical defocus on human contrast sensitivity

Atchison, David A., Woods, Russell L., & Bradley, Arthur (1998) Predicting the effects of optical defocus on human contrast sensitivity. Journal of the Optical Society of America A: Optics and Image Science, 15(9), pp. 2536-2544.


We used diffraction modulation transfer functions and model eyes to predict the effect of defocus on the contrast sensitivity function (CSF) and compared these predictions with previously published experimental data. Using the principle that optically induced changes in the modulation transfer function should be paralleled by identical changes in the CSF, we used the modulation transfer function calculations with the best-focus CSF measurements to predict the defocused CSF. An aberration-free model predicted the effects of defocus well when the CSF was measured with small pupils (e.g., 2 mm) but not with larger pupils (6-8 mm). When the model included average aberrations, prediction of the defocused CSF with large pupils was better but remained inaccurate, failing, in particular, to reflect differences between individual subjects. Inclusion of measured aberrations for individual subjects provided accurate predictions in the shape of the monochromatic CSF of two of three subjects with hyperopic defocus and good predictions of the polychromatic CSF of two subjects with hyperopic defocus. Prediction of the effects of myopic defocus by use of measured individual aberrations of one subject were less successful. Hence a diffraction optics model can provide good predictions of the effects of defocus on the human CSF, given that one has knowledge of the individual ocular aberrations. These predictions are dependent on the quality of the aberration measurements.

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34 citations in Web of Science®
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ID Code: 5171
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:
Additional URLs:
Keywords: optical defocus, contrast sensitivity
ISSN: 1520-8532
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 1998 Optical Society of America
Copyright Statement: This paper can be found at the following URL on the OSA website: []. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.
Deposited On: 15 Nov 2006 00:00
Last Modified: 10 Aug 2011 18:25

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