1St Andrew's Neurosensory Unit, St Andrew's Hospital, Wickham Terrace‐ 4000

The findings in the pattern reversal V.E.C.P. 's have been examined in thirteen (13) patients, with proven or suspected pituitary tumours. Three (3) of these cases have been examined in detail, to highlight the unique capabilities of the pattern reversal V. E. C. P. in the assessment of conduction abnormalities of optic nerve and chiasma, due to compression by pituitary tumours. The V.E.C.P. is shown to be a uniquely sensitive procedure, which yields objective and quantative data about the functional status of the anterior visual pathways, in cases of suspected compression by pituitary tumours. It is suggested that subclinical optic nerve compression is best detected by serially monitoring optic nerve conduction with the pattern reversal V.E.C.P.