One of the most common first symptoms of MS, optic neuritis is an inflammation of the optic nerve which transmits images from the eye to the brain. When optic neuritis occurs, it usually affects only one eye, and can include disturbances such as, loss or temporary, reduction of vision, dull pain behind the eye or sharper pain on eye movement, dulling of color or flashing lights or blind spots.
If you find yourself reading about optic neuritis, it won’t be long before the words ‘multiple sclerosis’ begin to appear. Optic neuritis is one of the most common initial symptoms of MS. It is an inflammation of the optic nerve that is responsible for transmitting images from the eye to the brain. When it occurs, it usually only affects one eye. Optic neuritis can cause disturbances such as:
• Loss or temporary reduction of vision
• Dull pain behind the eye
• Sharper pain on eye movement
• Dulling of color
• Flashing lights or blind spot
It will normally be diagnosed by an ophthalmologist, and could include tests to monitor the efficiency of the optic nerve by testing the time taken by the brain to react to visual signals, as well as blood tests.
Further neurological tests may be requested, including an MRI scan of the brain to check for inflammation and any evidence of lesions, where MS is suspected.
Left untreated, optic neuritis will often improve on its own, normally within a few weeks. However, where the inflammation has been severe, a course of steroids may be recommended.
These may speed the recovery, although that remains controversial, but ultimately, they have no effect on the eventual outcome or the extent of the damage, and even where steroids are used there may be a long delay between the early stages of recovery as the inflammation goes down, to a full recovery.
Some lasting damage, such as difficulty differentiating color or a slight blurring of images, can occur although generally, recovery is good.
Certain triggers, such as heat, exercise or tiredness, may also temporarily cause a repeat of the visual disturbance, although this often subsides quickly.
Where optic neuritis is a symptom of MS, it is caused by the loss of the myelin covering of the optic nerve and retina. It is estimated that around 50% of people who experience an episode of optic neuritis will go on to receive an MS diagnosis.