Dr Ben Wild
Overview |
Our eyes are complicated systems. 7 out of the 12 cranial nerves that help control the entire body affect the eyes or muscles around the eyes in some shape or form. There are several large areas in the brain dedicated to vision interpretation, eye muscle movements, and recognition. Any disruption to these pathways can cause difficulty with vision, eye muscle teaming, or even difficulty understanding what you are seeing.
Multiple Sclerosis (MS) is a long lasting autoimmune condition characterized by the body’s defense system, the immune system, attacking the myelin sheath of it’s own neurons. The myelin sheath is a coating seen on some neurons, the white matter of the brain and several other nerves, that helps insulate the neuron and speed up signal transduction. This is a progressively worsening condition that has hugely variable prognoses.
In terms of how MS affects the eyes, 30% of MS diagnoses come after first presenting as optic neuritis (inflammation of the optic nerve). This results in pain around the eye that’s worse on eye movement, asymmetrical pupil reactions to light, decreased vision in one eye, abnormal color vision, and enlarged blind spots in one’s vision. 50% of patients with MS have had at least 1 episode of optic neuritis.
If MS affects the brainstem, the affected patient could notice double vision or nystagmus (oscillating eyes) and if it affects cerebrum of the brain it can cause a hemianopia (loss of half of the field of view to a blind spot). Double vision comes from either a loss of function of the 3rd cranial nerve (the affected eye would appear to be looking down and away, have a droopy eyelid and maybe a dilated pupil) or internuclear ophthalmoplegia (the affected eye cannot abduct (move away from the nose), and when looking the opposite way, has a nystagmus).
An image of a healthy retina and optic nerve. This is also noticed in retrobulbar optic neuritis (the most common optic neuritis associated with MS) because the inflammation is contained behind the eye.
Signs and Symptoms |
Signs
Episodes of impaired muscle function, abnormal pupil reflexes to light, impaired language and emotional functions, impaired coordination and balance.
Symptoms
Blurred or doubled vision, abnormal color vision, pain and loss of vision, trouble walking, numbness, pain or tingling of fingers/toes, muscle weakness in arms and legs, muscle spasms, speech problems, tremors, hearing loss, dizziness.
Causes and Risk Factors |
Causes
Autoimmune inflammation of the myelin sheath on nerves.
Risk Factors
Infectious agents of unknown origin, unknown environmental factors, genetics.
Prevention and Treatment |
Prevention
There are no known preventative measures.
Treatments
After confirming diagnosis with an MRI, cerebrospinal fluid analysis and blood tests;
· Immunotherapy to decrease rate of progression.
· Canes, braces, walkers for mobility.
· Rehabilitation activities.
Prognosis |
There are no known cures for MS at this time. The prognoses for MS are hugely variable. Some individuals only ever show mild symptoms, other individuals lose the ability to walk, become paralyzed, incontinent, have breathing difficulty, lose the ability to swallow, and more. Thankfully, researchers are currently working on strategies to greatly lower the rate of progression of MS in affected patients.