Optic neuritis refers to the inflammation or swelling of the optic nerve. The optic nerve is located at the back of the eye. It carries images or visual information to the brain to enable vision. An infected, swollen or damaged optic nerve can cause a reduction or loss of vision.
Optic neuritis can happen suddenly. It affects both eyes in children but one in adults.
Causes and Risk Factors
Doctors don’t seem to know the exact cause of optic neuritis. It is, however, believed to be an autoimmune disorder. Optic neuritis may be caused by the immune system attacking the optic nerve tissue by mistake. The immune system attacks myelin, the fatty coating that guards the optic nerve.
Several diseases can trigger an attack in the immune system. They include:
- Multiple sclerosis which causes inflammation. It damages the nerves in the brain and spinal cord
- Autoimmune diseases such as lupus
- Infections of the optic nerve, fungal infections and bacterial infections
- Respiratory diseases like pneumonia
- Neuromyelitis optica. The condition allows the cells and antibodies of the immune system to attack the brain, spinal cord and optic nerve
Optic neuritis attacks more females than males at the ratio of 3:2. It is mostly found in young adults between the ages of 20 and 45. The condition is prevalent among white people. Genetic mutations may also predispose one to optic neuritis.
Signs & Symptoms
Optic neuritis symptoms can develop suddenly or in a few days. The symptoms manifest themselves more when one is hot (after exercise) or tired. These symptoms also get worse if the optic nerve is not treated. They may include:
- Rapid, significant decrease in vision with visual acuity less than 20/400
- Vision loss in one eye
- Pain that gets worse with eye movement
- Pain in the back of your eye socket
- Fever-like flu
- Blurry vision
- A hole in the center of vision
- Dim vision, as if the lights have been turned down
- Colors appearing less vivid than normal
- Flashing or flickering lights
- Peripheral vision is affected
The eye professional will carefully examine an individual’s history. Information about recent illnesses, immunizations or neurological problems is useful. He/she will then do the following:
- Routine eye tests such as visual acuity testing, color vision testing and peripheral vision
- Use an ophthalmoscope to check for swellings in the optic nerve
- Check for pupil response to light
- Imaging which includes magnetic resonance imaging (MRI), CT scan and brain wave recording
- Optical coherence tomography (OCT) to measure how thick the retinal nerve fiber layer is
- Lumbar puncture (spinal tap)
- Blood tests to check for antibodies for neuromyelitis
- An optical visual evoked response to record the brain’s response to a visual stimuli
Treatment of optic neuritis is directed toward reducing the inflammation in the optic nerve.
Optic neuritis may go away on its own in some people. However, others will need medication to improve vision and keep the symptoms from worsening.
Corticosteroids are the most commonly used medications. Corticosteroids are administered either through a vein or orally. The drug helps with the recovery of vision but does not improve the final visual outcome. However, vision does not return to its original state in people with multiple sclerosis. There is also a chance that oral steroids may increase the risk of recurrence. If steroid treatment fails, plasma exchange therapy might help to recover vision.
Most cases of optic neuritis will heal on their own in 1-3 months. Some recover in 4 weeks. Recovery can also continue for several months. Most children with optic neuritis recover much of their vision. Generally, some people may experience mild or severe permanent vision loss. They may also lose some vision such that they cannot drive.
Individuals who develop optic neuritis without any disease recover much faster. Those with conditions like multiple sclerosis have a weaker outlook. Nevertheless, vision may return to normal.
It is possible for optic neuritis to recur especially for those with multiple sclerosis. Also, individuals who have recurrent optic neuritis may develop multiple sclerosis.
Due to the use of steroids, complications may arise. They include insomnia, mood swings, hypertension, nausea, weight gain and many more.
Patients will need to visit the doctor for check-ups especially for those with multiple sclerosis.
An doctor may need to re-evaluate a patient whose optic neuritis recurs after 2 months with prolonged pain and no recovery.