Optic Neuritis - Causes, Symptoms, Diagnosis & Treatment

Optic Neuritis

Dr.Aditya Neog profile Authored by Dr.Aditya Neog on 20 Apr 2015 - 12:34.

Optic neuritis is an acute inflammation (swelling) of the optic nerve. The optic nerve connects the eye to the visual centre in the brain. It transmits the impulses which allow a person to see the world. The inflammation may affect the optic nerve directly or it may spread from nearby structures, like the orbit, sinuses etc. Optic neuritis may affect children or adults, but is mostly seen among young adults in the age group of 20-40 years.

Optic neuritis can occur due to various conditions. In some there is demyelination of the nerve (Myelin is  the sheath covering the optic nerve and this gets damaged in demyelination). It can also occur due to some infections and due to auto immune diseases. At times, optic neuritis can occur after immunization. The most common cause of optic neuritis is multiple sclerosis according to the western literature. In the Indian scenario, multiple sclerosis is not so common. In India, infection and a different type of demyelination (involving the spinal cord seem to be more common than multiple sclerosis. In many cases, the cause is unknown, when it is called idiopathic. 

A patient with optic neuritis will have symptoms of decreased vision. Generally, one eye is affected. The decrease in vision may be very mild sometimes, but is usually quite significant. The decrease in vision is acute and progresses over few days. There is usually pain in and around the eye, which increases on eye movements. There will be difficulty in perceiving colors - colors especially red may appear to be faded. Many people feel a worsening of symptoms on increase of body temperature like taking a hot water bath; this is known as Uthoff’s phenomenon.

Most patients will have a gradual improvement of vision within the first month after the attack. The vision improvement continues gradually for a few months. Although the vision improvement is significant, most people have defective color vision and contrast sensitivity which can be permanent.

The diagnosis of optic neuritis is mainly done by clinical examination considering the patient’s symptoms and signs. Investigations are advised to find out the cause for the problem. These can include a MRI scan of the brain and spinal cord to look for demyelination. VEP (Visual Evoked Potential ) test may be advised to assess the signal conduction abilities of the optic nerve. Perimetry test is done to check the visual field to find out the extent of peripheral vision loss. If an infectious or auto-immune cause is suspected, blood tests will be advised to confirm the diagnosis.

The treatment for optic neuritis is based on the Optic Neuritis Treatment Trial (ONTT) which was a clinical study conducted in the USA. The patients are treated with steroid injections which are followed by oral steroids given for a period of few weeks. Most patients of this condition will improve spontaneously even without any treatment. Steroids may help to hasten the recovery and reduce the chances of recurrence.

Optic neuritis associated with multiple sclerosis may benefit with use of drugs known as interferons; while optic neuritis with spinal cord involvement may require immune-suppressive therapy. These treatments are usually considered in patients who have recurrent episodes.

Most people with optic neuritis regain good vision. If the vision loss is very severe, the process of recovery can go on for months. But, even after recovery, the affected eye will have subnormal color vision and contrast sensitivity. A small group of people can get recurrent attacks and in some people the fellow eye can also get affected.

All patients who had optic neuritis need regular periodic follow up with ophthalmologist and neurologist.

*Disclaimer This is not medical advice. The content is for educational purposes only. Please contact your doctor for any health care issues.