A Case of Optic Chiasm Stroke, A Condition Rarely Described in the Literature.

Acute bilateral blindness is an emergent condition that may signal life-threatening disease. The approach focuses on identification of life-threatening disease processes, while differentiating between ocular, psychogenic and neurologic aetiologies. We present the case of an 88-year-old man with multiple cardiovascular risk factors and bilateral chronic glaucoma and cataracts. He presented to the emergency department with sudden onset bilateral loss of visual acuity with no other relevant changes on physical examination, including other neurologic deficits. Ophthalmologic observation showed no sign of acute disease. Contrast orbit and cranioencephalic CT was unremarkable, so the patient underwent an orbit and cranioencephalic MRI that showed changes in fluid-attenuated inversion recovery (FLAIR) sequences and diffusion restriction involving the optic chiasm and the initial segment of the optic radiations bilaterally. Optic chiasm strokes are rare, owing to the rich supply of collateral circulation. The most frequent presentation is bitemporal hemianopsia but rarer presentations are described. Bilateral loss of visual acuity is very rare and infarction of the whole optic chiasm is unusual. LEARNING POINTS: Acute bilateral blindness has an extensive differential diagnosis but chiasmopathy of ischaemic aetiology is rare.Optic chiasm stroke is rarely described in the literature and can pose a diagnostic challenge as its presentation can vary greatly.