Optic neuropathy associated with botulinum A toxin in thyroid-related orbitopathy.

PURPOSE To report the development of optic neuropathy after botulinum A toxin injection for restrictive myopathy from thyroid-related orbitopathy (TRO). METHODS We retrospectively reviewed the records of three patients with TRO who underwent botulinum A toxin injection for restrictive myopathy and subsequently developed optic neuropathy. Development of optic neuropathy was measured by visual acuity, color vision testing, visual field testing, and relative afferent pupillary testing. RESULTS At 3 week follow-up after botulinum A toxin injection, three patients were noted to have clinical signs and symptoms of optic neuropathy in the ipsilateral eye following injection of botulinum A toxin for restrictive myopathy. Treatment with oral steroids followed by orbital wall decompression reversed the optic neuropathy. CONCLUSIONS To our knowledge, this is the first report of optic neuropathy associated with botulinum A toxin injection in TRO. Clinicians should be aware of this potential vision threatening complication.