The optic nerve carries visual information from your eye to your brain. Optic neuritis (ON) is when your optic nerve becomes inflamed.
ON can flare up suddenly from an infection or nerve disease. The inflammation usually causes temporary vision loss that typically happens in only one eye. Those with ON sometimes experience pain. As you recover and the inflammation goes away, your vision will likely return.
Other conditions result in symptoms that resemble those of ON. Doctors may use optical coherence tomography (OCT) or magnetic resonance imaging (MRI) to help reach the correct diagnosis.
ON doesn’t always require treatment and can heal on its own. Medications, such as corticosteroids, can help speed recovery. Most who experience ON have complete (or nearly complete) vision recovery within two to three months, but it may take up to 12 months to achieve the vision recovery.
You’re more likely to develop ON if:
- you’re a female between the ages of 18 and 45
- you’ve been diagnosed with multiple sclerosis (MS)
- you live at a high latitude (for example, Northern United States, New Zealand)
The cause of ON isn’t well understood. Most cases are idiopathic, which means they have no identifiable cause. The most common known cause is MS. In fact, ON is often the first symptom of MS. ON can also be due to infection or an inflammatory immune system response.
Nerve diseases that can cause ON include:
- neuromyelitis optica
- Schilder’s disease (a chronic demyelinating condition that begins in childhood)
Infections that may cause ON include:
Other causes of ON include:
- sarcoidosis, an illness that causes inflammation in various organs and tissues
- Guillain-Barre syndrome, a disease in which your immune system attacks your nervous system
- postvaccination reaction, an immune response following vaccinations
- certain chemicals or drugs
The three most common symptoms of ON are:
- vision loss in one eye, which can vary from mild to severe and lasts for 7 to 10 days
- periocular pain, or pain around your eye that’s often worsened by eye movements
- dyschromatopsia, or the inability to see colors correctly
Other symptoms can include:
- photopsia, seeing flashing lights (off to the side) in one or both eyes
- changes in the way the pupil reacts to bright light
- Uhthoff’s phenomenon (or Uhthoff’s sign), when eye vision worsens with an increase in body temperature
A physical exam, symptoms, and medical history form the basis of a diagnosis of ON. To ensure correct treatment, your doctor may perform additional tests to determine the cause of your ON.
Types of illness that can cause optic neuritis include:
- demyelinating disease, such as MS
- autoimmune neuropathies, such as systemic lupus erythematosus
- compressive neuropathies, such as meningioma (a type of brain tumor)
- inflammatory conditions, such as sarcoidosis
- infections, such as sinusitis
ON is as inflammation of the optic nerve. Conditions with symptoms resembling ON that aren’t inflammatory include:
- anterior ischemic optic neuropathy
- leber hereditary optic neuropathy
Because of the close relationship between ON and MS, your doctor may want to perform the following tests:
- OCT scan, which looks at the nerves in the back of your eye
- brain MRI scan, which uses a magnetic field and radio waves to create a detailed image of your brain
- CT scan, which creates a cross-sectional X-ray image of your brain or other parts of your body
Most cases of ON recover without treatment. If your ON is the result of another condition, treating that condition will often resolve the ON.
Treatment for ON includes:
- intravenous methylprednisolone (IVMP)
- intravenous immunoglobulin (IVIG)
- interferon injections
Use of corticosteroids such as IVMP may have adverse effects. Rare side effects of IVMP include severe depression and pancreatitis.
Common side effects of steroid treatment include:
- sleep disturbances
- mild mood changes
- stomach upset
Most people with ON will have partial to complete vision recovery within 6 to 12 months. Thereafter, healing rates decrease and damage is more permanent. Even with good vision recovery, many will still have a varying amount of damage to their optic nerve.
The eye is a very important part of the body. Address warning signs of lasting damage with your doctor before they become irreversible. These warning signs include your vision worsening for more than two weeks and no improvement after eight weeks.