The optic nerve sends messages from your eyes to your brain so that you can interpret visual images. When the optic nerve is irritated and inflamed, it doesn’t carry messages to the brain as well, and you can’t see clearly. Optic neuritis occurs when swelling (inflammation) damages the optic nerve
Inflammatory optic neuropathy is strongly associated with demyelinating disease (typical optic neuritis), particularly multiple sclerosis but also acute disseminated encephalomyelitis. It also occurs in sarcoidosis; in neuromyelitis optica spectrum disorder, which is characterized by serum antibodies to aquaporin-4; in association with serum antibodies to myelin oligodendrocyte glycoprotein; following viral infection (usually in children); in varicella zoster virus infection; in various autoimmune disorders, particularly systemic lupus erythematosus and Sjögren syndrome; during treatment with biologics; and by spread of inflammation from the meninges, orbital tissues, or paranasal sinuses.
Optic neuritis usually affects one eye. Symptoms might include:
Pain: Most people who develop optic neuritis have eye pain that’s worsened by eye movement. Sometimes the pain feels like a dull ache behind the eye.
Vision loss in one eye: Most people have at least some temporary reduction in vision, but the extent of loss varies. Noticeable vision loss usually develops over hours or days and improves over several weeks to months. Vision loss is permanent in some people.
Visual field loss: Side vision loss can occur in any pattern, such as central vision loss or peripheral vision loss.
Loss of color vision: Optic neuritis often affects color perception. You might notice that colors appear less vivid than normal.
Flashing lights: Some people with optic neuritis report seeing flashing or flickering lights with eye movements.
In acute demyelinating optic neuritis, intravenous methylprednisolone (1 g daily for 3 days followed by a tapering course of oral prednisolone) has been shown to accelerate visual recovery, although in clinical practice, the oral taper is not often prescribed and oral methylprednisolone may be used. Use in an individual patient is determined by the degree of visual loss, the state of the fellow eye, and the patient’s visual requirements. Phenytoin and amiloride may be neuroprotective in typical optic neuritis.
Atypical optic neuritis due to sarcoidosis, neuromyelitis optica, herpes zoster, or systemic lupus erythematosus generally has a poorer prognosis, requires immediate and more prolonged corticosteroid therapy, may require plasma exchange, and may necessitate long-term immunosuppression.
Among patients with a first episode of clinically isolated optic neuritis, multiple sclerosis will develop in 50% within 15 years but the visual and neurologic prognoses are good. The major risk factors are female sex and multiple white matter lesions on brain MRI.
Many disease-modifying drugs are available to reduce the risk of further neurologic episodes and potentially the accumulation of disability but each has adverse effects that in some instances are life-threatening. Fingolimod is associated with macular edema. Retinal nerve fiber layer optical coherence tomography quantifies axonal damage that can be used to monitor disease progression.