Adult-Onset Diplopia: Often Forgotten Causes.

I n general, the neuro-ophthalmic examination for an adult with recent-onset diplopia is straightforward. Topping the list of possible causes is ocular motor cranial nerve palsy. If examination findings are not consistent with an isolated cranial neuropathy, the clinician must broaden the differential diagnosis to include a variety of entities. Although the list of possible causes is long, those most frequently encountered include ocular myasthenia gravis, thyroid eye disease, Miller Fisher syndrome, and Wernicke encephalopathy. Yet, there are 4 additional causes of diplopia that also should be considered especially when there exists a history of childhood-onset strabismus, when extraocular movements are full, and when neurologic evaluation including imaging is normal.