To describe a rare case of unilateral light-induced amaurosis fugax in a patient with carotid artery occlusive disease. 

Light-induced amaurosis fugax (LIAF), known as retinal claudication, manifests as brief episodes of vision loss upon exposure to bright light. Unlike embolic phenomenon in amaurosis fugax, it is attributed to ocular hypoperfusion, secondary to severe carotid artery disease, leading to retinal ischemia causing a delay in regeneration of visual pigments in the photoreceptors. LIAF is an important symptom, which can herald a devastating ischemic stroke from severe carotid artery disease. Thus far, 22 such cases (15 unilateral and 7 bilateral manifestations) have been reported in ten case reports/series in the literature. Here, we illustrate one similar case. 

50-year-old man with long-standing cigarette smoking (reduced from 3 PPD for the last 40 years to ½ PPD currently), COPD, polysubstance use (methamphetamine/marijuana) and incidental remote right occipital infarct (no residual deficits), presented with 1-week history of sudden-onset, bright light-induced, brief (resolution in 1-2 hours) episodes of painless left monocular vision loss. Eye exam revealed superior nasal field cut in left eye (transient), decreased left visual acuity 20/40 (transient) and no ischemic changes. No associated temporal tenderness, jaw claudication, or any focal neurological deficits. CTA head and neck showed left carotid artery occlusion at the bifurcation and mild right carotid artery stenosis. Rest of work-up was unremarkable. Patient discharged home on dual anti-platelet therapy for 3 months, followed by Aspirin alone for life along with counseling for smoking cessation and avoidance of rapid drops in blood pressure. 

Light-induced amaurosis fugax is an unusual manifestation of stroke, seen in patients with severe carotid artery disease. Prompt recognition is critical to timely therapeutic intervention, to prevent major risk for ischemic stroke and possibly death.