Measuring contrast sensitivity with inappropriate optical correction

Russell L. Woods*, Niall C. Strang, David A. Atchison

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Spatial frequency-selective minima (notches) in the contrast sensitivity function (CSF) because of defocus can mimic those that occur with ocular disease. We examined the influence of measurement conditions on CSF shape in simulated clinical testing. CSF notches occurred with almost all levels of defocus for all subjects. Multiple notches were found under some conditions. Notches were found with defocus as small as 0.50 D. Effects of induced astigmatism depended on the orientation of the target. Notches were apparent in defocus conditions after stimulus size and room illuminance were modified and when subjects had insufficient accommodation to compensate for hypermetropic defocus. The equivalent of notches was not noted with the Pelli-Robson chart. As defocus-induced CSF notches may be mistaken for functional loss, careful refractive correction should be conducted prior to clinical or experimental CSF measurement, even at low spatial frequencies. (C) 2000 The College of Optometrists.

Original languageEnglish
Pages (from-to)442-451
Number of pages10
JournalOphthalmic and Physiological Optics
Issue number6
Publication statusPublished - 1 Nov 2000
Externally publishedYes

ASJC Scopus subject areas

  • Ophthalmology
  • Optometry
  • Sensory Systems


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