Optic Neuritis: Causes, Symptoms, Risk Factors, Diagnosis and Treatment

Optic neuritis is a result of injury to the optic nerve, a group of nerve fibers that transmits visual information from the eye to your brain. Pain when moving the eye and momentary loss of vision in one eye are common symptoms of optic neuritis.

The symptoms and indicators of ocular neuritis may arise early in the course of multiple sclerosis (MS) or they may develop later. The illness known as multiple sclerosis (MS) causes inflammation and damage to the brain and optic nerves.

Infections and immune system conditions such as lupus can also cause inflammation of the optic nerve. MS is not the only cause of this inflammation. In rare instances, a separate ailment known as neuromyelitis optica causes inflammation of the optic nerve and spinal cord.

The majority of individuals progressively restore their vision without the need for medical intervention after only one episode of optic neuritis. Sometimes, using steroids helps speed up the process of recovering vision after optic neuritis.

Causes Of Optic Neuritis

What precisely causes optic neuritis is unknown. It is believed that it develops when your immune system inadvertently targets the material covering your optic nerve, leading to inflammation and myelin damage.

Normally, electrical impulses from the eye go swiftly to the brain, where the myelin coating converts them into visual information. Optic neuritis obstructs this mechanism, making vision difficult.

Ocular neuritis is commonly associated with the following list of autoimmune diseases:

• Multiple sclerosis: Your immune system targets the sheath that covers the nerve fibers in your brain when you have multiple sclerosis. A person who gets optic neuritis once in their lifetime has a 50% probability of developing multiple sclerosis. Your chance of developing multiple sclerosis after visual neuritis is increased if an MRI reveals a brain lesion.
• Neuromyelitis optica: In this condition, inflammation damages the optic nerve and spinal cord. Although multiple sclerosis and neuromyelitis optica are similar diseases, neuromyelitis optica seldom causes damage to the nerves in the brain. However, neuromyelitis optica is more severe than multiple sclerosis (MS) and often leads to a delayed recovery after an event.
• Myelin oligodendrocyte glycoprotein (MOG) disease is mediated by antibodies. This disease may cause inflammation in the brain, spinal cord, or optic nerve. Inflammation can recur, much as it does with multiple sclerosis and neuromyelitis optica. Attacks against the myelin oligodendrocyte glycoprotein (MOG) usually result in better recovery.

It is crucial to consider additional associated factors, such as the following, when optic neuritis symptoms are more complex:

• Conditions: In addition to bacterial illnesses like syphilis, Lyme disease, and cat scratch fever, viruses like measles, mumps, and herpes can also cause optic neuritis.
• Other diseases: Lupus, sarcoidosis, and Behcet's disease are among the illnesses that can cause recurrent optic neuritis).
• Medication and toxins: There is evidence that the development of some drugs and toxins is connected to optic neuritis. One common ingredient in paints, solvents, and antifreeze is methanol; another common ingredient in ocular neuritis is ethambutol, a medicine used to treat tuberculosis.

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Symptoms Of Optic Neuritis

One eye is often affected by optic neuritis. Possible symptoms include:

• Pain: Most patients with optic neuritis experience eye pain that gets worse when they move their eyes. The sensation might occasionally be described as a dull ache behind the eyes.
• Loss of vision in one eye: The majority of persons experience a transient decrease in eyesight, albeit the degree of loss varies. Significant vision loss typically occurs over a few hours or days and becomes better over a few weeks or months. In certain cases, vision loss is irreversible.
• Loss of visual field: Any pattern, including central or peripheral vision loss, can result in side vision loss.
• Loss of eyesight in color: Color perception is often affected by optic neuritis. Colors may seem less vibrant than usual.
• Lights flashes

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Risk Factors Of Optic Neuritis

The following conditions increase the likelihood of optic neuritis:

• Age: The majority of adult patients with optic neuritis are in the 20–40 age range.
• Sex: Women are significantly more likely to get optic neuritis than males are.
• Race: Caucasian people tend to experience optic neuritis more frequently.
• Genetic mutations: You may be more prone to ocular neuritis or multiple sclerosis if you have specific genetic alterations.

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Diagnosis Of Optic Neuritis

You will most likely see an ophthalmologist for a diagnosis, which is usually based on an examination and your medical history. The ophthalmologist is probably going to do the following eye tests:

• An eye test once a year: Along with testing your eyesight and color perception, your eye doctor will measure your peripheral (side) vision.
• Microscopy of the Eye: During this examination, your doctor will shine a bright light inside your eye to look at the structures at the back. This eye exam evaluates the optic disc, which is the point in your eye where the optic nerve enters the retina. Swelling of the optic disc is observed in approximately one-third of cases of optic neuritis.
• Check for Pupillary Light Reaction: Your doctor might move a torch in front of your eyes to measure how your pupils respond to bright light. Your optic neuritis pupils will not contract as much in response to light as your healthy eyes' pupils will.

Further tests to detect optic neuritis include:

• Imaging with magnetic resonance imaging (MRI): During a magnetic resonance imaging (MRI) scan, radio wave energy pulses and a magnetic field are utilised to create images of your body. To help with the visibility of your optic nerve and other brain regions during an MRI and to screen for optic neuritis, you might be given a contrast injection.
• An MRI is essential to determine whether your brain has any lesions or damaged areas. These lesions show a high risk of developing MS. An MRI can help rule out other possible reasons of visual loss, such as cancer.
• Blood tests: A blood test might be done to check for specific diseases or antibodies. Neuromyelitis optica symptoms are associated with an antibody that causes severe optic neuritis. In individuals with severe optic neuritis, this test may be used to determine the risk of neuromyelitis optica. In the event of uncommon cases of optic neuritis, blood testing for MOG antibodies may also be conducted.
• Optical Coherence Tomography, or OCT: This test measures the retinal nerve fiber layer's thickness in the eye, which is frequently reduced due to optic neuritis.
• Visual field test: This test assesses the peripheral vision in each eye to see whether any vision loss is present. Optic neuritis can cause visual field loss in any pattern.
• Visual Evoked Response: During this test, you will be seated in front of a screen that alternates between a checkerboard pattern. Tiny patch wires installed in your head record your brain's responses to the images displayed on the screen. This type of test tells your doctor whether your optic nerve damage is slowing down the electrical signals that leave your brain.

Your doctor may strongly advise you to schedule follow-up exams two to four weeks following the onset of symptoms to confirm the diagnosis of optic neuritis.

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Treatment Of Optic Neuritis

Optic neuritis usually recovers on its own. Sometimes, optic nerve inflammation is treated with steroids. Mood fluctuations, weight gain, facial flushing, upset stomach, and insomnia are among the potential side effects of steroid medication.

• Intravenous injection is the standard route of steroid treatment administration. When treating typical optic neuritis, intravenous steroid therapy appears to have little effect on the amount of vision recovered, although it does expedite it.
• If steroid medicine is ineffective and the severe visual loss does not improve, some people may be able to recover their vision using plasma exchange therapy. Studies have not yet been conducted to determine whether plasma exchange treatment is effective in treating optic neuritis.

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