Twenty-four patients (47 eyes) affected by Graves’ disease were enrolled to evaluate the role of standardized echography, pattern electroretinogram (P-ERG), visual evoked potentials (P-VEPs) and automated perimetry in the early diagnosis of the compressive optic neuropathy (CON). The P-ERG amplitude reduction was the most sensitive parameter to demonstrate an early impairment of the optic nerve (ON) function. We found a significant negative correlation between the ON diameter and the P-ERG amplitude. VEPs responses were also altered, but their ability in detecting an early ON damage was less sensitive and specific than P-ERG. The visual field damage was often aspecific and delayed with respect to electrophysiological alterations.