Role of electrophysiologic testing in the preoperative evaluation of corneal transplant patients

We performed preoperative skin electrode bright-flash ERG and VEP testing on 32 patients undergoing elective penetrating keratoplasty. Twenty-six patients had unilaterally decreased vision and six had bilateral visual impairment. By combining our quantitative electroretinogram (ERG) and qualitative visual evoked potential (VEP) results with clinical findings, we were able to predict visual outcome in 92% of cases. Our findings suggest that bright-flash ERG and VEP testing are useful adjunct studies to clinical and ultrasound findings in patients with media opacities, comparison of a and b wave amplitudes with the fellow eye may yield prognostic information, a normal ERG and VEP in the presence of an equivocal afferent pupillary defect may signal a good visual prognosis, and ERG and VEP are not reliably predictive in patients with media opacity and amblyopia or macular disease.