What is optic neuritis?

Optic neuritis (ON) is the swelling or inflammation of the optic nerve. The optic nerve is responsible for transmitting the image from the retina to the brain. It is one of the most common disorders of the optic nerve, others include glaucoma, eye atrophy, or drusen.  

The specialist that diagnoses optic neuritis is an ophthalmologist.      

Disease prognosis   

Patients who get optic neuritis and do not have a linked disease, such as multiple sclerosis, have a higher chance of full recovery. However, although people with an autoimmune disease have a more negative prognosis, they may still regain vision in the affected eye.

What are the symptoms?   

If the neuritis affects the eye nerve fibers then it could cause short or long term vision loss.  There can also be changes in the way the eye reacts to bright lights, a chromatic vision loss, and the patient may also have pain with eye movement.

Tests for optic neuritis

To rule out other diseases, the patient will be given an eye colour test, a visual acuity test, visual field test, a brain MRI, and an indirect ophthalmoscopy to examine the optic disc.

What causes it?

The exact cause for optic neuritis remains unknown, but it is quite often linked to the following diseases:     

• Multiple sclerosis which is a chronic neurological disease that causes inflammation and demyeliation of the nerve fibres. Optic neuritis is often the first symptom of the disease, while it is estimated that half of all people with MS will develop optic neuritis at some point.   
• Cryptococcosis
• Respiratory infections
• Autoimmune diseases such as lupus
• Bacterial infections such as meningitis
• Viral infections such as chicken pox
• Vitamin B12 deficiency
• Leber’s optic neuropathy

When it develops with no known cause, it is known as idiopathic neuritis.

How can it be prevented?  

Consult an ophthalmologist and a neurologist so that they can study each case and detect risk factors. Quite often a brain MRI will be done if it is suspected that the patient may have one of the related diseases.  

What is the treatment?

Treatment for optic neuritis will vary depending on the related disease; sometimes intravenous or oral tablet form corticosteroids are used to shorten the duration of symptoms and accelerate visual recovery.

In some cases, vision may return within 2-3 weeks without any treatment.