Multiple sclerosis is an autoimmune disease that affects the central nervous system. In patients affected by this condition, inflammation occurs that damages the myelin (the sheath that surrounds the nerve fibers), the oligodendrocytes (the cells that produce myelin), and the nerve fibers themselves.
The pathological process leads to the formation of plaques—areas where myelin is damaged or absent—typical of multiple sclerosis. The plaques can form in different areas of the central nervous system (in the spinal cord, the cerebellum, and the optic nerves), and as the disease progresses and the chronic phase continues, they tend to evolve into sclerosis, with characteristics similar to scars.
Multiple sclerosis can appear at any age but is most commonly diagnosed between the ages of 20 and 40. It is estimated that around 2.8 million people in the world are affected by this disease, approximately 1.2 million in Europe and 137,000 in Italy. Women are more affected than men, in a ratio of about 3 to 1, and the disease is more common in Northern Europe, the United States, New Zealand, and Southern Australia, and less so in geographical areas closer to the equator. Multiple sclerosis can cause various types of symptoms depending on the location, number, and extent of the lesions. Many patients affected by this disease develop complications at the ocular level; among these, the most common are:
- Optic neuritis
Optic neuritis is the most common ocular complication of multiple sclerosis and is due to inflammation and plaque formation at the level of the optic nerves. This complication manifests as a decrease or loss of visual acuity in one eye, often accompanied by eye pain. The loss of vision progresses over several days and then reaches a stable phase, followed by either full or partial recovery.
- Diplopia (double vision)
Diplopia, or the perception of two images side by side or one above the other, is due to inflammation or damage at the level of the oculomotor nerves, which, together with the oculomotor muscles, are responsible for the coordinated movement of the eyes. Diplopia caused by multiple sclerosis may be temporary or persistent.
- Nystagmus
Nystagmus is an involuntary, rapid, and repetitive movement of the eyes caused by inflammation or damage to the areas of the brain that control eye movements. The uncontrolled eye movement can be horizontal, vertical, or rotational and can occur when trying to fixate on an object or while moving the eyes. Nystagmus can significantly impair vision quality since it prevents fixation, which is essential for visual acuity. This complication may be intermittent or persistent.
The ocular complications of multiple sclerosis usually have a negative impact on quality of life, generating limitations in both private and professional life, as well as isolation, anxiety, and depression. It is very important that patients experiencing visual problems undergo specific ophthalmological exams that allow the issue to be identified and, if possible, treated with the appropriate care and treatments available.
In case of suspected optic neuritis, it is necessary to undergo a thorough eye examination including various tests such as visual field testing, visual evoked potentials, and magnetic resonance imaging.
If the visual symptoms are related to a relapse of multiple sclerosis, the patient must be treated with high-dose corticosteroids. Additionally, in the case of diplopia, it is possible to use prismatic lenses to avoid image doubling and to carry out activities such as driving.
For nystagmus, therapeutic options are quite limited and include the use of corrective lenses aimed at compensating for visual defects caused not only by the nystagmus itself but also through the use of optical aids such as magnifying devices, commonly used in cases of low vision to help with daily activities.
In more severe cases of nystagmus, treatment may involve the administration of drugs based on botulinum toxin—which temporarily reduce the intensity of eye oscillations, improving fixation and visual acuity—or surgical intervention, although not always resolutive.
Treatments resulting from research advances now allow patients with multiple sclerosis to have a life expectancy not much different from that of unaffected individuals and to maintain a fair quality of life. Although there is currently no definitive cure for multiple sclerosis, the various types of therapy available today can certainly slow its progression and thus limit the effects of the disease on vision.
Dr. Alessia Bottoni
Biotecnologa e Ortottista esperta in Dry Eye
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