Amaurosis and optic disc blanching during upgaze in graves ophthalmopathy

A 60-year-old man with worsening Graves ophthalmopathy complained of complete loss of vision in the left eye on upgaze ("gaze-evoked amaurosis" [GEA]). Examination disclosed congestive orbital signs bilaterally. Upon upgaze, intraocular rose from 18 to 35 mm Hg in the left eye and visual acuity fell in that eye from 20/25 to no light perception. Evidence of optic nerve dysfunction and a swollen optic disc were present in the affected eye, and CT showed enlarged extraocular muscles with apical orbital compression of the optic nerve. Fundus photography performed during GEA disclosed blanching of the optic disc surface vessels in the affected eye. Surgical orbital decompression alleviated the congestive features and optic neuropathy and eliminated the GEA. This is the second case of GEA to be reported in Graves ophthalmopathy and the first to document blanching of optic disc vessels. The presumed mechanism of GEA in this patient is optic nerve ischemia, perhaps provoked by an elevation in intraocular pressure in a congested optic disc.