Predicting Variations in Visual Performance caused by Optical Defects - 2

Modelling of the effect of defocus on the contrast sensitivity function (CSF) predicts a non-monotonically decreasing function characterised by multiple local minima (notches).1,2 The notches are a consequence of defocus and aberration on the modulation transfer function (MTF). A recent study by our group1,2 demonstrated that, for 6mm pupils, the shape of defocussed CSFs and in particular the position (spatial frequency) and depth of notches could be predicted from the measured ocular aberration. Notches were well predicted and repeatable for hyperopic (negative) defocus, but predictions were less reliable for myopic (positive) defocus.