Optic neuropathy occurred in two patients suffering from Graves' disease with marked limitation of eye movement. Optic nerve changes were moderate. They consisted of parapapillary flame-shaped hemorrhages, swelling of the disc, and bundle defects in the visual field on the involved side. This clinical pattern suggested that the optic neuropathy was anterior and ischemic in nature. In one patient, symptoms of optic neuropathy were noted 3 days after starting stretching exercises with the ocular muscles, performed following a friend's advice in an attempt to prevent increase in restrictive myopathy. In patients with Graves' disease, it is conceivable that mild optic neuropathy occasionally occurs as a result of elevation in intraocular pressure, and stretching exercises of the ocular muscles might consequently favor such ischemic events. In the mechanisms of optic nerve involvement associated with Graves' disease, the role of ischemia should be considered in addition to the widely accepted role of optic nerve compression by enlarged extraocular muscles, at the level of the orbital apex.