Light induced amaurosis: a rare symptom of carotid stenosis

Abstract

INTRODUCTION: Light induced amaurosis refers to a transient monocular or binocular vision loss triggered by bright lights. Like amaurosis fugax, light induced amaurosis is associated with carotid artery stenosis but they differ from each other in presentation and pathophysiology. It is thought to be an impairment in the regeneration of retinal visual pigments caused by the inability of carotid circulation to sustain the increased metabolic activity occurring when the retina is exposed to bright lights. With this report we aim to present a case of light induced amaurosis and its management. CASE REPORT: We describe a 74-year-old man with the isolated complaint of monocular visual loss from his left eye when exposed to bright lights. These episodes were self-limited and lasted for several minutes. His vision was reportedly good between episodes. He also complained of headache and dizziness. There were no other focal neurological deficits present. The patient had a history of peripheral artery disease, chronic heart failure, hypertension, dyslipidaemia, permanent atrial fibrillation and had a history of heavy smoking in the past. Chronic medical therapy included anticoagulation with rivaroxaban, antiplatelet therapy with acetylsalicylic acid and atorvastatin. Imaging studies (doppler ultrasonography and Computed tomography angiography) revealed a significant morphologic stenosis of the left common carotid artery, left internal carotid artery with sub occlusive disease and right internal carotid artery with 70-75% stenosis (North American Symptomatic Carotid Endarterectomy Trial - NASCET). The vertebral arteries study did not reveal significant morphologic disease. The patient was submitted to left common and internal carotid artery endarterectomy and Dacron patch angioplasty. The visual symptoms progressively improved after surgical treatment. The dizziness and headache were completely gone. CONCLUSION: Light induced amaurosis is a rare and less known symptom associated with severe carotid artery stenosis. Its timely recognition is important to not deprive patients of timely treatment.

Keywords

• Light induced amaurosis
• carotid stenosis
• transient vision loss