Ophthalmic diagnoses in the ED: optic neuritis.

Optic neuritis is the most common cause of decreased vision due to optic nerve dysfunction in patients who are 20 to 40 years of age. Optic neuritis, or inflammation of the optic nerve, is primarily due to idiopathic demyelination. Demyelinative lesions seen in optic neuritis are not unlike those seen in plaque associated with multiple sclerosis. In fact, acute inflammatory demyelination of the optic nerve commonly occurs as an initial manifestation of multiple sclerosis. Key features of optic neuritis include a vision loss occurring over 1 to 10 days, color vision impairment, eye pain with motility, and an afferent pupillary defect. This significant diagnosis can be challenging to an emergency physician as it is relatively infrequently observed.