WHAT IS OPTIC NEURITIS?
It is an inflammation of the optic nerve that sometimes manifests itself in his head or disk and can be seen with the ophthalmoscope (papillitis). However, most often it is retrobulbar, appearing normal background (65%).
Although the disease can occur at any age is more common to begin to manifest between 20 and 30 years, with higher prevalence in women (75%) and in the Nordic countries, with an incidence almost twice the equatorial countries. In patients older than 50 years, the optic nerve involvement usually has a different origin, but not both inflammatory circulatory and ischemic optic neuropathy. Optic neuritis in Spain affects about 42,000 people, with an incidence of 90 per 100,000 inhabitants and its initial episode affects one eye in 70% of cases.
This disease is associated with demyelinating diseases such as multiple sclerosis (MS). In 10 years, 40% of patients develop MS, but the incidence rises to 56% if discovered brain lesions. In fact, an acute episode of optic neuritis may be the initial sign of MS. However, in some people, especially children younger than 12 years, optic neuritis may develop during or after a viral illness.
WHAT ARE THE SYMPTOMS?
The patient complains of decreased vision (within the first week of its inception, 52% had a visual acuity of less than 0.3, 48% from 0.2 to 0.1 and 38% worse than 0.05 and pain on eye movement (especially in adduction). Typically, retrobulbar pain is similar to sinusitis, reaching maximum severity within the first 24-36 hours and resolves spontaneously after 48 to 72 hours. If pain persists for a week, the ophthalmologist should suspect other causes of optic neuropathy.
Sometimes some patients complain of desaturation or lack of color intensity, and phosphenes or dyschromatopsia. The latter are caused by sounds or movements (occurring exclusively with horizontal movements of the eyes and noticing better in a dark or dimly lit, with eyes closed.
There are cases where the patient is aware of poor vision (as if the light intensity decrease) when exposed to bright light, in fact in those cases in which the disease is chronic indicate people see better in dim light. On the other hand there are patients who report Uhthoff phenomenon (transient episodes of twilight with blurred vision and color desaturation, and exercise-induced changes in temperature, such as when taking a hot shower) that occurs in 50% of cases. The occurrence of this phenomenon has a poor prognosis and is correlated with multifocal lesions of the brain and therefore develops a higher incidence of recurrent episodes of MS and optic neuritis.
HOW IS IT DIAGNOSED?
- Decreased vision (far and near)
- Dyschromatopsia (loss red / green color test Ishihara, etc.)
- Defect contrast sensitivity
- Reduced stereopsis test (Titmus Polaroid 3-D)
- Central visual field defect (central scotoma, paracentral or centrocecal) or peripheral (constriction)
- Severe positive afferent pupillary defect in the affected eye
- Electrophysiology (VEP) in the affected eye abnormal
- In some cases, optic nerve hyperemia or frank inflammation (papillitis)
The test requires a thorough evaluation of medical history, especially to rule out drugs that can cause toxicity to the optic nerve as ethambutol, isoniazid, phenothiazines, etc.. You should also investigate the use of alcohol, drugs (marijuana, etc..), Much stress and psychiatric disorders.
WHAT IS THE CLINICAL COURSE?
In a few days the pain and improve vision in most patients (92%) but not return completely. Often remains slightly blurred vision, faded or distorted and muted colors, until several months later. It is very rare to lose vision gradually.
Optic neuritis can recur in the same eye, the other eye or other parts of the central nervous system, brain or spinal cord. This can lead to recurrent episodes of decrease or loss of vision or other systemic neurological problems (motor or sensory) and muscle weakness with difficulty walking or coordinate movements, fatigue and exhaustion, paresthesias, dizziness or loss of balance, etc..
When patients are in remission (asymptomatic) can detect a temporal pallor of the optic nerve head and defects in the ganglion nerve fiber layer. This temporal optic nerve pallor occurs in 10% of patients suggesting that there has been a previous attack. When the patient recovers from the episode of optic neuritis, six months after the first attack, the optic nerve head is normal in 42%, temporal pallor appears in 28% and overall paleness by 18%. MS in remission optic nerve pallor is present in 38% of eyes. The optic atrophy is a late manifestation.
WHAT IS THE TREATMENT?
From the study of ONTT (Optic Neuritis Treatment Trial) doctors have found that treating patients with IV steroids (but not oral steroids) reduces the risk of developing MS later. This finding is very important since 50% of those with the first attack of optic neuritis develop MS. However, although this treatment has little or no impact on vision, it is very important for overall health.
The current protocol, based on the above studies, is IV steroids administered for three days followed by oral steroids 10 to 14 days. Some doctors prefer not to give any medication since in most vision improves spontaneously in the first two weeks. What is certain is that no ophthalmologist treats these cases with oral steroids alone, since it has been shown that patients managed in this way have a higher risk of repeated attacks of optic neuritis.