Pattern visual evoked potentials and pattern electroretinograms in hypothyroidism.

This study reports the pattern visual evoked potential (PVEP) findings in 10 patients with idiopathic hypothyroidism. Eight of these patients also had pattern electroretinography (PERG) performed and six were additionally seen after treatment with thyroxine. Only one patient had definitely abnormal PVEPs at the time of initial recording. PERGs at this time were of abnormal latency and subnormal amplitude. Following treatment with thyroxine the patient became euthyroid. Repeat electrodiagnostic testing now showed both PERGs and PVEPs within the normal range, having markedly improved in both latency and amplitude. This suggests that the PVEP delay was probably secondary to reversible central retinal dysfunction.