Vision loss due to atypical bilateral edema of the optic nerve in a patient with hereditary angioedema: A case report

Purpose: To describe a rare case of vision loss due to bilateral edema of the optic nerve in a patient with Hereditary Angioedema, treated with prophylactic C1-esterase inhibitor.Methods: A 60-year-old Caucasian male affected by Hereditary Angioedema with unknown genetic defect (HAE- UNK) was admitted to our hospital presenting bilateral vision loss (best corrected visual acuity of 20/32 in the right eye and hand motion in the left eye) during an HAE attack. Intravenous administration of C1- esterase inhibitor (C1-INH, 1500 IU, Berinert, CSL Behring) determined the resolution of facial and periorbital swelling, however visual impairment persisted, in contrast with previous attacks experienced by the patient. Fundus examination revealed a vital optic disc without papilledema in both eyes. Magnetic resonance imaging (MRI) of the head and orbits showed bilateral edema of the optic nerve sheath. Treatment with intravenous and oral steroids was ineffective. Subsequently, a prophylactic treatment strategy with subcutaneous C1-esterase inhibitor was started (7000 IU every four days).Results: Complete regression of edema of the optic nerves was observed by imaging at two months of follow-up after chronic treatment with C1-esterase inhibitor (7000 IU every four days). Complete restoration of visual acuity was achieved (BCVA 20/20 in both eyes) and multimodal imaging of the optic nerves demonstrated the absence of anatomical and functional damage.Conclusion: Patients affected by HAE may show atypical presentation with edema of the optic nerves without involvement of the optic nerve head. They may significantly benefit from prophylactic and chronic treatment with C1-esterase inhibitor.