Acute optic neuritis (ON) must be considered in any patient presenting with vision loss, especially if unilateral and associated with discomfort on eye movement.
ON is a finding often (50%) associated with Multiple Sclerosis (MS), with or without other classic MS abnormalities such as transverse myelitis, internuclear ophthalmoplegia, and paresthesias.
A normal fundoscopic examination does not rule out ON, as 50% of acute cases affect the retrobulbar space.
Positive pertinent clinical findings may include an afferent pupillary defect in the affected eye and/or visual acuity abnormality, ranging from subtle deficit to total blindness.
