Acute Optic Neuritis

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Synonyms

optic neuropathy, retrobulbar neuritis, papillitis,

Overview

Acute optic neuritis is inflammation of the optic nerve, leading to sudden, unilateral vision loss and often eye pain with movement. It typically involves demyelination and is most commonly a symptom of multiple sclerosis (MS) or other neuroinflammatory conditions. While recovery often occurs spontaneously within weeks or months, high-dose intravenous steroids may accelerate this process. A significant proportion of patients, especially those with MS-related lesions on MRI, have an increased risk of developing MS. 

Symptoms

Acute optic neuritis symptoms often include a sudden decrease or loss of vision, usually in one eye, along with pain that worsens with eye movement, and a significant loss of color vision where colors appear dull and faded. You might also notice changes in your peripheral or central vision, or even experience temporary flashing lights. These symptoms develop over hours to days and typically improve over weeks to months, but some people experience permanent vision loss. 

Causes

Acute optic neuritis is most often caused by an autoimmune reaction damaging the optic nerve, particularly in demeyelinating diseases like multiple sclerosis. Other causes include certain infections (Lyme disease, herpes, syphilis), systemic inflammatory diseases (lupus, sarcoidosis), certain drugs (ethambutol), and toxins. In many cases, the specific cause remains unknown, classifying the condition as idiopathic. 

Prevention

Preventing acute optic neuritis is challenging as its specific causes are often unclear, but strategies focus on managing underlying conditions like multiple sclerosis and autoimmune disorders, avoiding known triggers, and maintaining general eye and nerve health. This includes timely diagnosis and treatment of conditions like multiple sclerosis (MS), which is a major cause, and addressing deficiencies or infections that can trigger optic neuritis. While there’s no guaranteed method for prevention, reducing inflammation, protecting the eyes from injury, and managing systemic diseases are key aspects.  

Diagnosis

Acute optic neuritis is diagnosed through a combination of the patient’s medical history, a thorough ophthalmologic exam with tests like the swinging flashlight test and color vision testing, and specialized imaging like an MRI of the brain and orbits. Key findings include subacute vision loss, often with pain on eye movement, a relative afferent pupillary defect (RAPD) or Marcus Gunn pupil, reduced color vision, and central visual field defects. The MRI is crucial for detecting optic nerve inflammation and brain lesions associated with Multiple Sclerosis (MS), helping to confirm the diagnosis and assess the risk for other conditions. 

Prognosis

The prognosis for acute optic neuritis is generally good, with most people experiencing partial or full vision recovery within weeks to months, though some may have persistent visual issues like reduced color vision or contrast sensitivity. Recovery is often faster and the risk of developing multiple sclerosis (MS) or other neurological conditions depends on factors like the specific type of optic neuritis and whether treatment is given. 

Treatment

Acute optic neuritis is treated with high-dose intravenous corticosteroids (like methylprednisolone) followed by an oral prednisone taper, which speeds visual recovery but doesn’t change the long-term visual prognosis, and is more effective for those with severe symptoms or MS lesions on an MRI scan. Other treatments depend on the cause; for severe cases unresponsive to steroids, plasma exchange (PLEX) may be used, while MS or autoimmune conditions like MOGAD or NMOSD may require disease-modifying therapies. Some cases, especially if symptoms are mild, may improve on their own with watchful waiting.