Optic neuritis is an inflammation of the optic nerve which is a bundle of nerve fibers that transmit visual information from your eye to your brain. The condition often manifests as blurry or hazy vision affecting one eye only. Eye pain or discomfort may occur in optic neuritis, more so when the eye moves. In multiple sclerosis patients optic neuritis is a common symptom and is often one of the first symptoms of disease.
It is important to understand that visual problems associated directly with multiple sclerosis are not due to the eyeballs themselves. Our eyes gather light that is then sent through the optic nerve bundle as electrical signals to our brain. A significant portion of our brain is involved in processing of these signals. The optic nerve bundle is the wiring that connects an eye to the brain. Research as to why exacerbations (MS flare up’s or attacks) often include optic nerves continues to take place as it is one of the more common symptoms of multiple sclerosis.
There are several aspects of MS that may also impact vision. Muscles for example that allow us to move our eyes in unison are controlled by nerves. If nerves associated with this control are attacked eye muscles may not move eyes in a coordinated fashion often resulting in”double vision” called Diplopia or resulting in what is known as Nystagmus which is involuntary movement of one or both eyeballs.
About Optic Neuritis:
The term “Neuritis” is defined as inflammation of a nerve. When an MS exacerbation (attack or flare-up) occurs and an optic nerve is involved affecting vision this is called optic neuritis. Women are three times as likely to have optic neuritis develop than men statistically. Optic neuritis can be caused by other disorders as well. For many people not diagnosed with multiple sclerosis optic neuritis results in questions as to whether any other indicators of MS might be present. An MRI might be prescribed to further investigate the cause.
In an multiple sclerosis exacerbation vision tends to decline over a week to 10 days and then stabilizes. Some visual recovery often takes place within 30 days of the attack subsiding. Some 30-35% of people also experience colors of flashing lights often experienced in eye movements or moving from dark to bright rooms for example. Strange perceptions of objects moving in space also may occur, it is known as Pulfrich phenomenon.
The optic nerves are resilient and generally will heal in time. However, impacts on other areas of the brain related to sightedness may not recover as fully as optic nerves tend to recover.
Common symptoms of optic neuritis are:
- Vision loss in one eye – this is temporary and can last seven to 10 days
- Periocular pain – when pain worsens when the eye moves
- Dyschromatopsia – inability to see colors correctly
- Photopsias – seeing flashing lights
- Changes to how the pupil reacts to light
- Uhthoff’s phenomenon – vision worsens with an increase in body temperature
Diagnosing Optic Neuritis:
Your doctor can recommend a number of tests to help diagnose optic neuritis.
If your doctor suspects optic neuritis, they will likely refer you to an eye specialist, called an ophthalmologist.
Common tests used to diagnose the condition include:
- ophthalmoscopy, which examines your optic disk for swelling
- pulpillary light reaction test, which tests how your pupils respond to light
- MRI scan, which allows for better viewing of your optic nerve
- visual response test to detect optic nerve damage
ONTT (Optic Neuritis Treatment Trial) was a long term research study into optic neuritis and multiple sclerosis.
ONTT Study Major Findings:
Several findings stand out, said Roy W. Beck, MD, PhD, who conceived the trial, which he called “a major advance, in terms of having a better understanding of the natural untreated disease course and of understanding the effects of high- and low-dose corticosteroids.” Dr. Beck is director of the Jaeb Center for Health Research Clinical Trials Coordinating Center in Tampa, Fla.
Combination drugs speed recovery. ONTT helped define the role of corticosteroids in the treatment of acute optic neuritis. When the study originated, many doctors were treating the condition with oral corticosteroids. The study looked at oral prednisone vs. high-dose intravenous methylprednisolone vs. placebo and found that the IV methylprednisolone followed by a tapering course of oral prednisone accelerated visual recovery by a few weeks.
Recovery of vision occurs with or without treatment. The investigators found that the choice of regimen has no effect on final visual outcome. Most patients in the placebo group recovered vision, on average, in six to eight weeks. Oral prednisone alone was no better than placebo with respect to visual recovery and, in fact, was associated with twice the risk of recurrent optic neuritis. It is no longer recommended for an initial episode of typical, presumed demyelinative optic neuritis. The therapy should include either high-dose methylprednisolone or nothing, Dr. Beck explained.
White matter lesions predict MS. The initial findings, published 16 years ago, in 1992, still apply today, said Dr. Beck. But in addition to determining a therapeutic regimen, the ONTT defined the risk factors for development of MS among patients with optic neuritis. The presence of asymptomatic white matter lesions on the MRI scan is the strongest predictor for MS. Few patients at the start of the study had any history of MS, but over time the numbers grew.
Outcome favorable and stable. For the majority of patients, even those with MS, the visual outcome is good. Those who develop MS are more likely to exhibit abnormal visual function findings, but their vision is normal about 60 percent of the time.
There was little or no change in visual acuity in the affected eye between the 10- and 15-year examinations, in most patients. After 15 years, 72 percent of patients with optic neuritis had visual acuity of 20/20 or better; and 66 percent had acuity of 20/20 or better in both eyes.
ONTT Study Treatment Consensus:
Short-term considerations. Treating the patient with active optic neuritis involves weighing the benefits and risks. “Keeping in mind that high-dose steroids merely alter the rate of recovery and not the ultimate recovery, I typically will discuss the risk, benefits, side effects and alternatives with each patient in light of their unique medical history and individual preferences,” said Andrew G. Lee, MD, professor of ophthalmology, neurology and neurosurgery at the University of Iowa in Iowa City. “I tend to offer high-dose methylprednisolone, 1 g IV qd for three days followed by oral prednisone, 1 mg/kg qd for 11 days, followed by a four-day taper, to most patients unless there is a contraindication or patient preference dictates otherwise.” He added that short-term side effects in young, otherwise healthy people are unlikely but may include hyperglycemia, gastrointestinal symptoms, mood alteration, insomnia and weight gain.
Long-term considerations. Dr. Bhatti said that physicians can now speak with some confidence about a patient’s risk of developing MS at five, 10 and 15 years. For example, a doctor can tell the patient with optic neuritis and an abnormal brain MRI (one lesion or more) that her/his risk of MS within 15 years is 72 percent. Armed with this information, the physician may offer disease-modifying drugs such as beta-interferon or glatiramer acetate to reduce the risk of a second demyelinating event that could result in MS.
Treatment Options for Optic Neuritis:
Optic neuritis with multiple sclerosis is nearly always associated with a recent or active exacerbation and treatments prescribed are often steroids to help reduce the inflammation. Without treatment visual recovery still occurs in almost all cases, the steroid is given to shorten the duration of symptoms.
The usage of these steroids should be thoroughly discussed with your health care provider.
The early stages of recovery can happen quite quickly, probably due to the inflammation of the optic nerve going down. In one of the key clinical trials for optic neuritis, 79 per cent of people showed signs of improvement within three weeks, and 93 per cent began to recovery within five weeks.
A full recovery can take longer, and you may find that your sight continues to improve for up to a year after your first symptoms.
Although your sight may recover to normal levels, in terms of standard visual acuity charts, you may notice some subtle lasting changes to your vision. For example, you may find it harder to pick out colours, or distinguish between different colours. Your depth perception may also be affected and things may not appear as sharp as they used to.
You may also find that certain triggers, such as heat, exercise or fatigue, make your vision temporarily worse, or that it varies during the day or from one day to the next.
After a positive diagnosis of multiple sclerosis a phenomenon known as Uhthoff’s Sign may also occur. Uhthoff’s sign occurs often among people who endure MS with sensitivity to heat. Uhthoff’s sign it is believed results in slower nerve conduction in damaged areas of the central nervous system and can thus impact vision should it occur. It is transient and tends to go away rapidly.
Pregnant women should have an informed discussion with both their neurologist and obstetrician should optic neuritis occur during pregnancy.
Choosing the Right Specialist With Optic Neuritis And MS:
Choosing the right specialist should optic neuritis occur can be confusing.
If a person has not yet been diagnosed with multiple sclerosis their primary care physician may refer them to a ophthalmologist or a neurologist.
For patients who have been positively diagnosed with MS a neurologist appointment should be scheduled. The visual sensory system itself as a whole is generally managed by neurologists and thus optic neuritis as well. Visual impairment is considered a primary symptom in MS and requires specialized knowledge of MS diagnosis, symptoms and treatment.
Neuromyelitis optica (NMO) and NMO Spectrum Disorder (NMOSD), also known as Devic’s disease, is an autoimmune disorder in which immune system cells and antibodies primarily attack the optic nerves and the spinal cord. The damage to the optic nerves produces swelling and inflammation that cause pain and loss of vision; the damage to the spinal cord causes weakness or paralysis in the legs or arms, loss of sensation, and problems with bladder and bowel function.
NMO is a relapsing-remitting disease, like MS. During a relapse, new damage to the optic nerves and/or spinal cord can lead to accumulating disability. Unlike MS, there is no progressive phase of this disease. Therefore, preventing attacks is critical to a good long-term outcome.