From the Guidelines
Positive visual phenomena in optic neuritis include phosphenes, photopsias, and Uhthoff's phenomenon, which are crucial to recognize as they can be the first manifestation of multiple sclerosis or other demyelinating disorders. These phenomena occur due to inflammation of the optic nerve, causing abnormal electrical discharges that the brain interprets as visual stimuli 1. Phosphenes are brief flashes, sparks, or colored lights in the visual field, more noticeable in low-light conditions. Photopsias are persistent light sensations, appearing as shimmering, flickering, or pulsating lights. Uhthoff's phenomenon is characterized by temporary worsening of visual symptoms with increased body temperature, such as during exercise, hot showers, or fever, due to blocked nerve conduction in demyelinated nerve fibers.
Key characteristics of optic neuritis include:
- Painful visual loss, although it can be painless
- Inflammation of the optic nerve, which can be unilateral or bilateral
- Association with multiple sclerosis, neuromyelitis optica, or other infectious or granulomatous conditions
- Importance of MRI in diagnosis, particularly to evaluate for abnormal enhancement and signal changes within the optic nerve and to assess the brain for associated intracranial demyelinating lesions 1.
Patients experiencing these symptoms should seek prompt ophthalmological evaluation, as optic neuritis can be the first manifestation of multiple sclerosis or other demyelinating disorders. The diagnosis is supported by contrast-enhanced MRI showing optic nerve enhancement, and brain MRI abnormalities are also common 1. It is essential to differentiate optic neuritis from other conditions, such as neuromyelitis optica spectrum disorders, ischemic or infectious diseases, and to consider the presence of red flags, such as posterior optic nerve involvement or simultaneous bilateral optic nerve involvement 1.
From the Research
Positive Visual Phenomena in Optic Neuritis
- Optic neuritis is a condition that can cause visual disturbances, including positive visual phenomena such as phosphenes or flashes of light 2.
- The exact mechanisms of positive visual phenomena in optic neuritis are not fully understood, but they are thought to be related to demyelination and inflammation in the optic nerve 3.
- Treatment of optic neuritis with corticosteroids, such as methylprednisolone, can help to reduce inflammation and improve visual outcomes, but it may not directly affect positive visual phenomena 4, 5.
- In some cases, immunomodulatory therapies, such as interferons, may be used to treat optic neuritis and reduce the risk of multiple sclerosis, but their effect on positive visual phenomena is not well established 2.
- Immunoadsorption therapy has been shown to be effective in treating steroid-refractory optic neuritis, and it may also influence the humoral immune response and remove demyelination products and immunological mediators from plasma 6.
Types of Optic Neuritis
- Typical optic neuritis is the most common form of the condition, and it is often associated with multiple sclerosis 3.
- Atypical optic neuritis, including antibody-mediated forms such as aquaporin-4 (AQP4)-IgG neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD), can have different prognoses and treatments 3.
- Differentiating between typical and atypical optic neuritis is important, as it can affect treatment and outcomes 3.
Treatment and Outcomes
- Treatment of optic neuritis is tailored to the cause of the condition, and it may include corticosteroids, immunomodulatory therapies, and plasma exchange 3.
- Typical optic neuritis usually recovers well without treatment, but recovery may be expedited by steroids 3.
- Atypical optic neuritis often requires more aggressive treatment, including intravenous steroids and long-term immunosuppressive therapy 3.