Optic neuritis


Optic neuritis is a demyelinating inflammation of the optic nerve. It is also known as optic papillitis, neuroretinitis when there is a combined involvement of optic disc and surrounding retina in the macular area and retrobulbar neuritis. It is most often associated with multiple sclerosis, and it may lead to complete or partial loss of vision in one or both eyes. Other causes include:
  1. Idiopathic
  2. Hereditary optic neuritis
  3. Parainfectious optic neuritis
  4. Infectious optic neuritis
Partial, transient vision loss can be an indication of early onset multiple sclerosis. Other possible diagnoses include diabetes mellitus, low phosphorus levels, or hyperkalaemia.

Signs and symptoms

Major symptoms are sudden loss of vision, sudden blurred or "foggy" vision, and pain on movement of the affected eye. Early symptoms that require investigation include symptoms from multiple sclerosis, episodes of "disturbed/blackened" rather than blurry indicate moderate stage and require immediate medical attention to prevent further loss of vision. Other early symptoms are reduced night vision, photophobia and red eyes. Many patients with optic neuritis may lose some of their color vision in the affected eye, with colors appearing subtly washed out compared to the other eye. Patients may also experience difficulties judging movement in depth which can be particular troublesome during driving or sport. Likewise transient worsening of vision with increase of body temperature and glare disability are a frequent complaint. However, several case studies in children have demonstrated the absence of pain in more than half of cases in their pediatric study population, with the most common symptom reported simply as "blurriness." Other remarkable differences between the presentation of adult optic neuritis as compared to pediatric cases include more often unilateral optic neuritis in adults, while children much predominantly present with bilateral involvement.
On medical examination the head of the optic nerve can easily be visualized by a slit lamp with a high positive lens or by using direct ophthalmoscopy; however, frequently there is no abnormal appearance of the nerve head in optic neuritis, though it may be swollen in some patients. In many cases, only one eye is affected and patients may not be aware of the loss of color vision until they are asked to close or cover the healthy eye.

Cause

The optic nerve comprises axons that emerge from the retina of the eye and carry visual information to the primary visual nuclei, most of which is relayed to the occipital cortex of the brain to be processed into vision. Inflammation of the optic nerve causes loss of vision, usually because of the swelling and destruction of the myelin sheath covering the optic nerve.
The most common cause is multiple sclerosis or ischemic optic neuropathy due to thrombosis or embolism of the vessel that supplies the optic nerve. Up to 50% of patients with MS will develop an episode of optic neuritis, and 20-30% of the time optic neuritis is the presenting sign of MS. The presence of demyelinating white matter lesions on brain MRI at the time of presentation of optic neuritis is the strongest predictor for developing clinically definite MS. Almost half of the patients with optic neuritis have white matter lesions consistent with multiple sclerosis.
Some other common causes of optic neuritis include infection, autoimmune disorders, methanol poisoning, Vitamin B12 deficiency, and diabetes, or an injury to the eye.
Less common causes are: papilledema, brain tumor or abscess in the occipital region, cerebral trauma or hemorrhage, meningitis, arachnoidal adhesions, sinus thrombosis, liver dysfunction, or late stage kidney disease.
Cause and Rank based on DeathsAnnual Num Cases TOTAL Annual Cases leading to Optic NeuritisPercentPrognosis and Treatment
Multiple Sclerosis 400, 042146,23245%Most Common cause, Almost all patients will experience some form of vision dysfunction. Partial vision loss can occur through the duration of the disease, Total vision loss occurs in severe cases and late stages
Blood Clot 17,00016,7775%Reversible if early and before reduced Blood flow causes permanent damage.
Nerve Pinch, NOT REPORTED4%Usually heals itself, Treatment Not needed
Injury to Optic Nerve 23,82720,121<1%Depends on Severity, Usually Treatable
Liver Dysfunction If untreated can lead to Failure 141,21111,9827%Poor Outcomes and Progresses and can lead to total vision loss
Reduced Kidney Function 33,2121,1122%Poor Outcomes - Usually permanent nerve damage at this stage
Papilledema, 45,8889,2313%Depends on Severity
Meningitis 2,521189<1%Depends on Severity
Other Infections 5,561<1%Good Outcomes, Treatable with Antibiotics or other Microbial drugs
Diabetes Late Stage has worse prognosis 49,56221,11215%Type 1 carries poor prognosis, Type 2 can be treated and vision returned
Unknownn/a2%

Demyelinating recurrent optic neuritis and non-demyelinating (CRION)

The repetition of an idiopathic optic neuritis is considered a distinct clinical condition, and when it shows demyelination, it has been found to be associated to anti-MOG and AQP4-negative neuromyelitis optica
When an inflammatory recurrent optic neuritis is not demyelinating, it is called "Chronic relapsing inflammatory optic neuropathy"
When it is anti-MOG related, it is demyelinating and it is considered inside the anti-MOG associated inflammatory demyelinating diseases.
Some reports point to the possibility to establish a difference via OCT

Treatment

In most MS-associated optic neuritis, visual function spontaneously improves over 2–3 months, and there is evidence that corticosteroid treatment does not affect the long term outcome. However, for optic neuritis that is not MS-associated the evidence is less clear and therefore the threshold for treatment with intravenous corticosteroids is lower. Intravenous corticosteroids also reduce the risk of developing MS in the following two years in patients with MRI lesions; but this effect disappears by the third year of follow up.
Paradoxically, oral administration of corticosteroids in this situation may lead to more recurrent attacks than in non-treated patients. This effect of corticosteroids seems to be limited to optic neuritis and has not been observed in other diseases treated with corticosteroids.
A Cochrane Systematic Review studied the effect of corticosteroids for treating people with acute optic neuritis. Specific corticosteroids studied included intravenous and oral methylprednisone, and oral prednisone. The authors conclude that current evidence does not show a benefit of either intravenous or oral corticosteroids for rate of recovery of vision. There is a number of reasons why this might be the case.

Epidemiology

Optic neuritis typically affects young adults ranging from 18–45 years of age, with a mean age of 30–35 years. There is a strong female predominance. The annual incidence is approximately 5/100,000, with a prevalence estimated to be 115/100,000.

Society and culture

In Charles Dickens' "Bleak House", the main character, Esther Summerville, suffers from a transient episode of visual loss, the symptoms of which are also seen in people who have optic neuritis. Legal historian Sir William Searle Holdsworth, suggested that the events in "Bleak House" took place in 1827.
In the episode of Dr. Quinn, Medicine Woman, "Season of Miracles", in season five, Reverend Timothy Johnson is struck blind by optic neuritis on Christmas Day, 1872. He remains blind for the duration of the series.