Teprotumumab for Dysthyroid Optic Neuropathy: Early Response to Therapy.

A 45-year-old male presented with active progressive thyroid eye disease refractory to intravenous steroids and right orbital radiation. Visual acuity, left relative afferent pupillary defect, and Humphrey visual field defects were consistent with worsening left dysthyroid optic neuropathy. Orbital MRI demonstrated extraocular muscle enlargement and effacement of the left optic nerve sheath. After 2 infusions of teprotumumab, the patient's visual acuity, relative afferent pupillary defect, Humphrey visual fields, proptosis, and extraocular muscle size improved. This is the first report of dysthyroid optic neuropathy responsive to teprotumumab, and it supports the need for further studies to better understand the role of teprotumumab in treating sight-threatening thyroid eye disease.