Optic neuritis (ON; see the image below) is a demyelinating inflammation of the optic nerve that often occurs in association with multiple sclerosis (MS) and neuromyelitis optica (NMO). A gradual recovery of visual acuity with time is characteristic of optic neuritis,  although permanent residual deficits in color vision and contrast and brightness sensitivity are common. 
Signs and symptoms
The patient’s history may reveal the following signs and symptoms of optic neuritis:
Preceding viral illness
Rapidly developing impairment of vision in 1 eye or, less commonly, both eyes: During an acute attack 
Dyschromatopsia (change in color perception) in the affected eye: Occasionally may be more prominent than the decreased vision 
Retro-orbital or ocular pain: In association with the vision changes and usually exacerbated by eye movement; the pain may precede vision loss
Uhthoff phenomenon, in which vision loss is exacerbated by heat or exercise
Pulfrich phenomenon, in which objects moving in a straight line appear to have a curved trajectory: Presumably caused by asymmetrical conduction between the optic nerves
Patients with MS may have recurrent attacks of optic neuritis,  which means that a history of previous episodes of decreased vision in the same or fellow eye may be elicited.
Signs and symptoms of optic neuritis may include the following:
Decreased pupillary light reaction in the affected eye: A relative afferent pupillary defect (RAPD) or Marcus Gunn pupil commonly is found; in bilateral cases, the RAPD may not be apparent
Varying degrees of vision reduction: From a mildly decreased visual acuity to complete vision loss
Abnormal contrast sensitivity and color vision: In almost all patients with adult optic neuritis who have decreased visual acuity
Altitudinal field defects
Papillitis (swollen disc): Found in one third of patients with optic neuritis
See Clinical Presentation for more detail.
The following blood tests can be performed to exclude causes of optic neuropathy other than optic neuritis:
Erythrocyte sedimentation rate
Thyroid function tests
Rapid plasma reagin
Mitochondrial deoxyribonucleic acid (DNA) mutation studies
Magnetic resonance imaging (MRI) is highly sensitive for and specific in the assessment of inflammatory changes in the optic nerves, and for central nervous system white matter lesions. MRI also helps to rule out structural lesions. [10, 11]
Visual evoked potentials (VEPs) can be considered in patients with suspected optic neuritis. They may be abnormal even when MRI of the optic nerve is normal. VEPs often show a loss of P100 response in the acute phase. P100 recovers with time, but it usually shows a markedly prolonged latency that persists indefinitely, even after clinical recovery.
See Workup for more detail.
For most patients with optic neuritis, treatment and recovery proceed as follows:
Visual function begins to improve 1 week to several weeks after onset, even without any treatment
Permanent residual deficits in color vision and contrast and brightness sensitivity are common 
Pharmacologic therapy in optic neuritis (ON) is directed at ameliorating the acute symptoms of pain and decreased vision caused by demyelinating inflammation of the nerve; varying regimens of corticosteroids have been used for this purpose.
For patients with optic neuritis whose brain lesions on MRI indicate a high risk of developing clinically definite MS, treatment with immunomodulators (eg, interferon [INF] beta-1a, INF beta-1b, glatiramer acetate) may be considered. 
Optic neuritis (ON) is a demyelinating inflammation of the optic nerve that typically first occurs in young adulthood (see the image below). Many cases of optic neuritis are associated with multiple sclerosis (MS) or neuromyelitis optica (NMO), but optic neuritis can occur in isolation.  In cases associated with MS, optic neuritis is commonly the first manifestation of the chronic demyelinating process.  Long-term follow-up studies have indicated that up to 75% of female patients initially presenting with optic neuritis ultimately develop MS. (See Presentation and Prognosis.)
Occasionally, optic neuritis can result from an infectious process involving the orbits or paranasal sinuses or occur in the course of a systemic viral infection. [18, 19, 20, 21, 22, 23, 24, 25, 26] Certain optic neuropathies, such as anterior ischemic optic neuropathy (AION) and compressive and hereditary optic neuropathies, can resemble optic neuritis. 
This article reviews optic neuritis as a primary demyelinating inflammation of the nerve occurring either in isolation or in association with MS or NMO. (NMO is a severe form of a demyelinating disease; it affects the optic nerves and the spinal cord, causing recurrent attacks of blindness and paralysis. [28, 29] ) Much information has been gleaned from the Optic Neuritis Treatment Trial (ONTT), and the reader is encouraged to review the follow-up data from this study. (See Etiology, Treatment, and Medication.) [30, 12, 31, 2]
For patient education information, see Multiple Sclerosis.
Most cases of optic neuritis are associated with MS, even though optic neuritis can occur in isolation. In MS-associated and isolated, monosymptomatic optic neuritis, the cause is presumed to be an autoimmune reaction that results in a demyelinating inflammation of the nerve. Pathologic studies in patients with optic neuritis associated with MS have shown that the demyelinative lesions in the optic nerve are similar to the MS plaques seen in the brain, with an inflammatory response marked by perivascular cuffing, T cells, and plasma cells. However, little is known about the pathology of isolated optic neuritis.
In a single case of chronic, isolated optic neuritis, a biopsy specimen showed the presence of perivascular lymphocytic infiltration, multifocal demyelination, and reactive astrocytosis in the retrobulbar portion of the optic nerve. Abnormal intrathecal immunoglobulin G (IgG) synthesis, reflected as the presence of oligoclonal bands in the cerebrospinal fluid (CSF), is found in 60-70% of patients with isolated optic neuritis, suggesting an immunologic etiology similar to MS.
NMO has been recognized as a distinct inflammatory demyelinating disease consisting of optic neuritis in combination with longitudinally extensive transverse myelitis. NMO is associated with the presence of a specific serum, NMO IgG autoantibody, which targets the water channel aquaporin-4. [32, 33, 34]
As previously stated, optic neuritis can occasionally result from an infectious process involving the orbits or paranasal sinuses or occur in the course of a systemic viral infection. [18, 19, 20, 21, 22, 23, 24, 25, 26]
Studies from Sweden and Denmark have reported an annual incidence of 4-5 cases of new-onset optic neuritis per 100,000 persons.  Patients living in temperate climates seem to be predisposed to optic neuritis.
Race-, sex-, and age-related demographics
Optic neuritis appears to affect Caucasians more commonly than it does other races. Women are affected twice as often as men. 
Typically, patients with first-time, acute optic neuritis are young adults aged 20-45 years. Atypical cases of optic neuritis may be seen in elderly patients. Bilateral optic neuritis in childhood is not uncommon, and it is believed there is less risk of progression to MS.
In contrast to ischemic optic neuropathies and compressive optic neuropathies, a gradual recovery of visual acuity with time is characteristic of optic neuritis.  For most patients with optic neuritis, visual function begins to improve 1 week to several weeks after onset, even without any treatment. However, permanent residual deficits in color vision and contrast and brightness sensitivity are common. 
Decreased visual acuity secondary to optic neuritis may be permanent. Final visual outcome may be better in patients with an isolated episode of optic neuritis, compared with patients who eventually develop MS. Up to 75% of female patients and 35% of male patients initially presenting with optic neuritis ultimately develop MS. [36, 37, 38]
Patients with silent demyelinative lesions elsewhere in the brain, observed on magnetic resonance imaging (MRI) performed at the initial presentation, are more likely to develop definite MS in the long term than are patients with isolated optic neuritis. In addition, patients who have recurrent episodes of optic neuritis may be more likely to develop MS.
In patients with normal findings on MRI, a 16% risk of progression to clinically definite MS exists at 5-year follow-up.
Most patients with relapsing NMO have an aggressive form of the disease that is associated with frequent and severe exacerbations and poor prognosis.
What would you like to print?