Optic neuritis

Optic neuritis (ON) is a debilitating condition that is defined as inflammation of cranial nerve II which results in disruption of the neurologic pathways that allow visual sensory information received by the retina to be able to be transmitted to the visual cortex of the brain. This disorder of the optic nerve may arise through various pathophysiologic mechanisms, such as through demyelination or inflammation, leading to partial or total loss of vision. Optic neuritis may be a result of standalone idiopathic disease, but is often a manifestation that occurs secondary to an underlying disease.

Signs of ON classically present as sudden-onset visual impairment in one or both eyes that can range in severity from mild visual blurring to complete blindness in the affected eye(s). Although pain is typically considered a hallmark feature of optic neuritis, the absence of pain does not preclude a diagnosis or consideration of ON as some patients may not report any pain.

ON is typically subtyped into "typical" ON and "atypical" ON. The most commonly considered etiologies are multiple sclerosis (MS), neuromyelitis optica (NMO) / neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein-antibody-associated disease (MOGAD). Other etiologies include idiopathic ON, infections (e.g., syphilis, Lyme disease, and viral infections such as herpes simplex and varicella-zoster), and systemic autoimmune diseases (e.g., systemic lupus erythematosus and sarcoidosis).

Diagnosis of ON can be made with a combination of symptom manifestation, clinical exam findings, imaging findings, and serologic studies.

Modern medical practice employs high-dose steroids, such as IV methylprednisolone, as the first-line treatment for optic neuritis.

Optic neuritis should not be confused with optic neuropathy, which is a condition manifesting as visual impairment that occurs as a result of damage to the optic nerve from any cause – one of those causes being optic neuritis.