Effect of contact lens correction of sine wave contrast sensitivity in keratoconus patients after penetrating keratoplasty.

Contrast sensitivity testing reveals visual deficits not detected by standard acuity tests, providing a more sensitive measure of visual performance. Sine wave contrast sensitivity functions were examined for spectacle and contract lens correction of keratoconic eyes after penetrating keratoplasty (PKP). Contrast sensitivity was significantly higher for middle and high spatial frequencies with a rigid gas permeable contact lens than with glasses, even when Snellen acuity was identical for both forms of correction. Contrast performance correlated with subjective assessments of vision quality. This may be related to the quality of the keratometry mire images and suggests that mild irregularities in graft contour may be affecting contrast sensitivity. When considering the options for optical correction of grafted eyes, an evaluation of contrast sensitivity may help determine whether contact lens correction would optimize visual performance.