Pattern-reversal visual evoked potentials in hepatic cirrhosis.

Whole-field pattern-reversal VEPs (VEP) were examined in fifteen patients screened for hepatic cirrhosis. Twelve age- and sex-matched normal individuals and twenty-four psychotic patients on maintenance neuroleptic medication served as controls. There were no differences in latency or amplitude of the major positive component VEP (P100) to binocularly or monocularly presented reversing patterns between hepatic and control groups. Pre-exposure to flicker (the "photostress test") caused no abnormalities of VEP. Only in one patient with hepatic cirrhosis did monocular stimulation in the photostress condition cause a marked delay of P100. It is possible that this was an idiosyncratic response and that visual abnormalities detectable with the VEP technique can be attributed to other factors such as poor attention or accompanying disorders of the visual system.