“Attack!” yell the soldiers. Their opponents are just stupefied! Not only are they caught off guard by the suddenness, what shocks them most is when they see who they are up against…their own comrades! It’s a coup!!
We have heard of many such instances in history when a section of the soldiers turn against their very own. But do you know that the same can also happen in your own body? It is called an auto-immune disease. Some of these auto-immune diseases are known to affect the eye and cause:
Optic neuritis is the inflammation of the optic nerve which is the nerve that carries visual information from eye to your brain for interpretation.
Though we do not know the exact cause of optic neuritis yet, but it is believed to occur when your own immune system attacks the myelin (which is a sheath covering the optic nerve) causing inflammation (your body’s reaction to the attack in which there is swelling and loss of function) and damage to the myelin.
Myelin is responsible for the impulses to travel quickly along the nerves from your eyes to your brain. As optic neuritis causes a disruption in this process, your vision is affected.
Optic Neuritis has been commonly found to be associated with the following auto-immune diseases (or diseases where your own body mistakenly attacks optic nerve tissue):
• Multiple Sclerosis: A disease in which the brain and spinal cord are affected.
• Neuromyelitis Optica: Similar to multiple sclerosis, in this disease there is inflammation of the optic nerve and spinal cord.
• Sarcoidosis and SLE (Systemic Lupus Erythematosus) are other conditions associated with optic neuritis.
• Infections like Measles, Mumps, Influenza, Syphilis, Tuberculosis, Lyme Disease, HIV, Hepatitis B, Herpes, Chicken pox and fungal infection called Cryptococcosis.
• Leber’s Optic Neuropathy (A rare eye condition which tends to run in families)
• Cranial Arteritis: this is an inflammation of the blood vessels which supply blood to your brain and eyes.
• Drugs like Ethambutol
• Radiation Therapy: This is not seen commonly.
• Tumors, Toxins or Nutritional Deficiencies which hamper the nerve’s impulse conducting abilities.
Women and young adults (20-40 years) are more at risk for developing optic neuritis.
Optic Neuritis is commonly seen in one eye, but can affect both your eyes together.
• Pain: Pain due to optic neuritis can peak in a period of several days. It is worse with movement of your eyes.
• Loss of Vision: It is aggravated by heat or exercise. It may even be permanent. Sometimes, it can even develop within the course of a few hours.
• Flashing or Flickering Lights
• Colour vision: This is often affected especially the colour red. You may notice that colours appear less vivid than normal.
• Colour Vision Testing
• MRI of the brain and optic nerve
• Visual Acuity Testing
• Visual Field Testing
• Ophthalmoscopy to see the optic disc (the part of your optic nerve which is seen on clinical examination)
• Pupillary light reaction test
• Visual Response Test / Visual Evoked Potentials Test: This is done to look for problems in the brain that cause eye troubles.
• Permanent damage to your optic nerve
• Decreased vision: Your visual acuity may be lessened permanently
• Side effects due to steroids which are used in the treatment.
Usually, optic neuritis improves on its own. Sometimes steroids may be used to reduce the inflammation in the nerve. These may be administered:
• Intravenous: this means that the steroids are given into your blood vessels for a few days.
• Oral: After an intravenous steroid therapy, you may be given oral steroid medications
Sometimes, plasma exchange therapy may be given if steroid therapy does not succeed.
Visual loss due to optic neuritis usually worsens over the first week. After this, your vision will stabilize at the same level for 3-8 weeks. After this, improvement begins to occur.
95% of people who suffer from optic neuritis are able to regain much of their vision within 6 months.
But, approximately 19% have a recurrence in the same eye and 17% in the other eye in the next ten years.
People with auto-immune diseases are more likely to have recurrent attacks. The other way round is also true: that means if you have optic neuritis, there are more chances of you developing Multiple Sclerosis in the future.