Optic Neuritis

What is Optic Neuritis?

Optic neuritis is inflammation of the optic nerve, the bundle of nerve fibers that transmits visual information from the eye to the brain. It often causes sudden, painful vision loss in one eye. Optic neuritis is commonly associated with multiple sclerosis (MS), but can also occur on its own or with other autoimmune conditions such as neuromyelitis optica (NMO).

Symptoms

• Sudden loss of vision in one eye, often developing over hours to days
• Pain with eye movement, especially when looking up or to the side
• Dimming or washing out of colors (dyschromatopsia)
• A dark spot or blind area in the center of vision (central scotoma)
• Flashing lights with eye movement (phosphenes)

Diagnosis

Diagnosis typically begins with a thorough eye examination including visual acuity testing, pupil evaluation (looking for a relative afferent pupillary defect), color vision testing, and visual field testing. An MRI of the brain and orbits with contrast is critical — it confirms optic nerve inflammation and helps assess the risk of developing multiple sclerosis. Optical coherence tomography (OCT) measures the thickness of the retinal nerve fiber layer and can track recovery over time.

Treatment

Many cases of optic neuritis improve on their own over several weeks. High-dose intravenous corticosteroids (such as methylprednisolone) may be recommended to speed visual recovery, particularly if the vision loss is severe. While steroids accelerate recovery, they do not change the final visual outcome in most cases. If an underlying condition like MS or NMO is identified, long-term disease-modifying therapy is typically recommended to prevent future episodes.