Abstract

Changes in the contrast sensitivity function (CSF) often have been used to demonstrate the effects of an experimental treatment or die process of some ophthalmic disease. For example, spatial frequency selective minima (notches) in the CSF have been reported in certain ophthalmic conditions.¹,² Similar notches in the CSF of otherwise normal eyes have been predicted from consideration of optical theory,³, ⁴ yet surprisingly notches have only recently been reliably demonstrated with astigmatic defocus⁵ and spherical defocus.⁶,⁷,⁸ One early study⁹ appears to show moderate notches with 2.0D myopic defocus. The authors did not comment on the notches. ⁹ Other workers have unfortunately often averaged CSFs between subjects or between hyperopic and myopic defocus which would tend to hide any notches.⁴, ¹⁰

© 1997 Optical Society of America