Optic neuritis is a kind of nerve disease that affects the optic nerve – the nerve that transmits visual information from the eye to the brain. Some common symptoms of the ailment include sudden vision loss, eye pain, and changes in colour perception.
While the condition is often temporary, it can be alarming, causing significant discomfort and anxiety. Another concern is that it may indicate an underlying health issue, particularly neurological disorders like multiple sclerosis (MS).
Hence, it is critical to understand the causes, diagnosis, and treatment options for optic neuritis. It can help with timely intervention and effective management.
What is Optic Neuritis?
Optic neuritis refers to the inflammation of the optic nerve. When it happens, the normal transmission of visual signals gets disrupted. The patient experiences symptoms, such as blurred vision, loss of colour vision, and sometimes even temporary blindness in one eye. The condition typically affects adults aged between 20 and 40, and women are more susceptible to it than men.
Although optic neuritis can occur in one or both eyes, one eye getting affected is more common. The progression is quite rapid as symptoms usually develop over a few hours to a couple of days and tend to peak within a week.
Common Optic Neuritis Causes
Here are the major factors that can lead to inflammation of the optic nerve:
1. Autoimmune Disorders
A predominant cause is multiple sclerosis (MS). In fact, optic neuritis is often the first symptom of MS, although it can also manifest later. Other autoimmune conditions, such as neuromyelitis optica spectrum disorder (NMOSD) and lupus are also associated with optic neuritis.
Research indicates that close to 50% of patients with typical optic neuritis will develop Multiple Sclerosis within 15 years.
2. Infections
Our nerves are prone to damage (neuropathy) from infections, and our optic nerve is no different. Infections are often the reason behind paediatric optic neuritis. Both viral and bacterial infections can trigger optic nerve inflammation, particularly in children. These include:
- Measles, mumps, chickenpox
- Shingles, herpes viruses, HIV
- Mosquito-borne viruses
- Lyme disease, syphilis, tuberculosis
These infections can themselves cause inflammation (direct inflammation) in the optic nerve, or optic neuritis may be a result of an immune response that occurs due to these infections.
3. Medication Side Effects and Toxins
Both prescribed and non-prescribed medications could at times lead to optic neuropathy. Here are the most common ones:
- Medicines for treating infections (ethambutol, isoniazid, chloramphenicol, or sulfa-type antibiotics, etc.)
- Arrhythmia drugs (amiodarone or digoxin)
- Quinine-type malaria medicines
- Anticancer drugs (methotrexate, tamoxifen, vincristine, etc.)
- Tobacco and nicotine containing products
4. Nutritional Deficiencies
Low levels of vitamin B, particularly vitamin B12, can cause permanent, severe nerve damage. The patient may suffer from optic neuropathy, which is frequently confused with optic neuritis. Unlike optic neuritis, nutritional optic neuropathy is often bilateral and progresses slowly.
5. Other Neurological Conditions
Apart from MS and NMOSD, conditions such as sarcoidosis and idiopathic intracranial hypertension may also cause inflammation in the optic nerve.
Optic Neuritis Symptoms
Symptoms of optic neuritis revolve around eyes and problems in vision. Common symptoms include:
- Sudden vision loss in one eye, usually peaking within a few days
- Pain in or behind the eye, that worsens with movement
- Reduced colour perception, especially red colour
- Flashing lights or flickering vision
- Central scotoma (a gap in the centre of vision)
Some people may experience only mild symptoms, while others may go through significant vision loss. However, most patients recover their vision partially or completely over time.
Diagnosing Optic Neuritis
Early diagnosis of the disease is crucial, especially if the condition is due to a systemic disease like MS. The diagnostic process typically includes a number of tests:
1. Comprehensive Eye Exam
An ophthalmologist or neurologist will conduct a thorough eye examination to assess your vision clarity, colour vision, and eye movement. Further, a fundoscopic exam may reveal optic disc swelling. However, in some cases (retrobulbar neuritis), the optic nerve may appear normal.
2. Visual Evoked Potential (VEP) Test
This test measures the electrical response of your brain to visual stimuli. It can help detect slowed signal transmission due to optic nerve damage. A protective myelin sheath protects the optic nerve, but when it gets damaged, the nerve cells are unable to send signals properly, causing various kinds of vision loss.
3. MRI of the Brain
A magnetic resonance imaging (MRI) scan is a critical tool for detecting optic nerve inflammation and identifying brain lesions typical of multiple sclerosis. If you have ON, the affected optic nerve(s) look brighter than a normal optic nerve.
4. Lab Tests
Blood and urine tests are generally done to look for signs of infection and autoimmune causes. A lumbar puncture or spinal tap may also be done to find signs of infection or other symptoms.
Treatment Options for Optic Neuritis
Optic neuritis treatment typically focuses on reducing inflammation and managing the underlying issue – to limit damage to the optic nerve, reduce pain, and take care of vision loss. It means timely neuro ophthalmology treatment is essential.
1. Intravenous Corticosteroids
High-dose intravenous (IV) anti-inflammatory corticosteroids are commonly used for three to five days to speed up recovery. After this, you may be prescribed lower-dose oral steroids, which may later taper. So, it’s vital to follow your doctor’s instructions.
2. Treating underlying causes and contributing factors
These treatments vary depending on the cause. To exemplify, you are recommended antibiotics for bacterial infections, and treatments like PLEX (plasma exchange) to control immune system activity if tests show you have an autoimmune disorder like NMO or MOGAD.
Prognosis and Outlook
What you may expect with optic neuritis varies according to its type. There may be pain and vision loss, and one or both eyes may be affected. Most optic neuritis patients recover vision over time – ranging from several weeks to months. However, some may experience lasting visual issues, particularly if the root cause was some chronic condition like MS.
Diagnosis of optic neuritis can take different approaches, and it may be frustrating to go through the process. Discuss your concerns with your healthcare provider so that they know your need for encouragement and reassurance. Seek the support of your family and friends and maintain a positive outlook.
Conclusion
Optic neuritis is a serious but often manageable condition that may be an early indicator for neurological diseases. Early diagnosis, timely treatment, and regular monitoring can go a long way in preserving vision and managing underlying causes.
If you or someone you know experiences sudden vision changes or eye pain, it’s critical to seek prompt medical attention. Reach out to highly experienced eye specialists at Sohana Hospital, the most trusted eye care hospital in Mohali.
