Optical neuritis and Multiple Sclerosis
What is it?
Optical neuritis is an inflammation of the optic nerve and is a common manifestation of multiple sclerosis, an inflammatory-demyelinating central nervous system disease.
Multiple sclerosis (MS) is a chronic debilitating neurological disease, affecting mainly young adults. It is characterized by the inflammation and demyelination of nerve fibers, and axonal degeneration. Although the exact cause of the disease is unknown, we know that it is an autoimmune disease. This means that the cells of the immune system will attack structures of it’s own body, in this case the myelin.
Optic neuritis may be the first manifestation or first outbreak of the disease in 20-30% of patients, and up to 50% of MS patients suffer during the course of the disease.
Symptoms and signs of multiple sclerosis may be multiple, and depend mainly on the central nervous system areas in which demyelination occurring. In the case of optic neuritis produce inflammation and demyelination of the optic nerve.
Typical symptoms of optic neuritis are "blurred vision" predominantly central, and altereded chromatic vision (especially intense for red) that is established sub acutely in 7-10 days. Up to 90% of patients present associated retroocular pain, which is triggered or worsened by eye movements.
The diagnosis of optic neuritis is mainly clinical. In the ophthalmological examination there will be an afferent relative pupillary defect in the affected eye, diminished visual acuity ,and a central scotoma in the visual field study. It is possible to observe inflammation in the optic nerve or optic neuritis, but frequently (up to 2/3 of patients) there aren’t any alterations to be found, because the inflammation occurs at a retrobulbar level (behind the optic nerve ).
A optical neuritis episode, like any outbreak of MS, can be treated by using intravenous corticosteroids, in order to shorten the duration of symptoms and speed visual recovery. Treatment with corticosteroids will not influence the functional prognosis or long-term recovery nor risk of developing multiple sclerosis in the future. Regarding this risk, various clinical trials have shown that the onset of an immune therapy after a first suggestive episode of multiple sclerosis, it delays the onset of a second outbreak of the disease and therefore diagnosis.
Consulting with an ophthalmologists and a neurologists specialized in these pathologies can help to better understand the particular risk of each patient, and therefore be able to advise on the most appropriate therapy at all times. The prognosis of optic neuritis is often good, although some small visual disturbances remain. A brain MRI must be performed on all patients with suspected optic neuritis, which will also help determine the risk of developing MS by detection of oligoclonal bands in the cerebrospinal fluid.