Contrast sensitivity after penetrating keratoplasty.

Abstract

Contrast sensitivity testing in the corneal transplant patient may enhance our assessment of visual performance, which is traditionally evaluated using Snellen acuity only. To evaluate contrast sensitivity function after penetrating keratoplasty, we studied 29 patients with anatomically successful corneal grafts and a best corrected visual acuity of 20/50 or better. Graft patients were compared with an age-matched control group including persons with comparable visual acuities without ocular disease. In addition to a complete ophthalmic examination, all subjects underwent contrast sensitivity testing using a computer-generated sinusoidal grating system as well as a commercially available contrast sensitivity wall chart. Data indicate that, despite comparable Snellen visual acuity, the contrast sensitivity curves for graft patients were depressed overall compared with those of normal subjects except at the lowest spatial frequency. However, comparison of grafted eyes to contralateral eyes with corneal disease in a small subset of patients with bilateral disease shows a trend toward higher contrast sensitivity values in the eyes that had been operated on. These data suggest that despite an improvement in contrast sensitivity with penetrating keratoplasty, an eye with a corneal transplant is not entirely normal from a visual standpoint. Nonacuity parameters may be important indexes for assessing real-world visual function in the graft patient, although the clinical role of these tests is not yet completely defined.