Abnormalities of visual evoked responses in hyperprolactinaemia.

The relationship between the visual evoked response (VER) and chiasmal lesions remains unclear, although a few published studies have reported waveform distortions as the major abnormality. In this study of 10 female and 2 male patients we carried out a retrospective analysis of the latencies and waveforms of their full field and half field VERs to pattern reversal stimulus. CT scanning showed minimal suprasellar involvement in 3 patients. The VER in 2 of these 3 patients showed slight prolongation in latency and waveform distortions. In 4 of the remaining 9 patients with no suprasellar involvement, the VER showed waveform distortions but normal latencies. We conclude that waveform distortion of the VER is an early finding in patients with pituitary tumours, even in the absence of suprasellar extension.