Multiple sclerosis is accompanied by optic neuritis, and there is demyelination of the optic nerve, causing the action potential to be propagated more slowly along axons. But how does this lead to blurred vision?
Demyelination per se is not the whole story behind the blurring of vision seen in MS patients.
MS results in an inflammation of the optic nerve (optic neuritis) and demyelination of the optic nerve fibers. It is commonly seen in MS, and is associated with blurred vision, basically because the signals are not sent properly along the optic nerve. Blurred vision in MS can have several reasons. These include:
- On the one hand blurring of vision is caused by the swelling and loss of optic nerve fibers due to the inflammatory effects accompanying optic neuritis.
- The demyelination of the optic nerve fibers associated with optic neuritis caused by MS disrupts signal transmission especially in the central eye field, leading to blurry parts in the center of focus due to impaired neurotransmission.
- Another symptom of MS is double vision, this is caused by demyelination of neurons in the brainstem that coordinate the control of the muscles that control eye movement. If the eye muscles are not working properly, and especially if one side of the brain is affected more than the other, it will cause blurred vision, because both eyes do not move in a synchronized fashion anymore.