What is optic neuritis (inflammation of the optic nerve)?

From the Guidelines

Optic neuritis is an acute inflammatory condition of the optic nerve, which can be unilateral or bilateral, and is often associated with multiple sclerosis, presenting with painful visual loss, but can also be painless. This condition is characterized by inflammation of the optic nerve, which carries visual information from the eye to the brain, and can cause sudden vision loss in one eye, often accompanied by pain that worsens with eye movement 1. The primary differential consideration includes multiple sclerosis, neuromyelitis optica, neuromyelitis optica spectrum, or other infectious or granulomatous conditions.

Key Features of Optic Neuritis

• Typically causes sudden vision loss in one eye
• Often accompanied by pain that worsens with eye movement
• Can be associated with multiple sclerosis
• Other symptoms may include reduced color vision, flashing lights, and a visual field defect called a central scotoma
• Inflammation damages the myelin sheath surrounding nerve fibers, disrupting signal transmission along the optic nerve

Diagnosis and Treatment

The diagnostic work-up should include a complete ophthalmological evaluation, MRI, and visual evoked potentials 1. Treatment usually involves high-dose intravenous methylprednisolone, followed by oral prednisone with a taper over 11 days. While this treatment speeds recovery, most patients improve spontaneously within weeks to months even without intervention. MRI scans of the brain and orbits are typically performed to evaluate for MS lesions and rule out other causes of vision loss 1.

Importance of Prompt Medical Attention

Prompt medical attention is important as optic neuritis can be the first sign of multiple sclerosis or other demyelinating diseases. Optic nerve imaging for lesion identification should include coronal fat-suppressed T2-weighted sequences with submillimetre in-plane resolution and slice thickness of 4-3 mm 1. Typical acute optic nerve lesions are characterized by T2 hyperintensity, associated optic nerve swelling, and contrast-enhancement. However, these findings are not multiple sclerosis-specific, since they can occur in other inflammatory conditions.

From the FDA Drug Label

6 Ophthalmic Diseases Severe acute and chronic allergic and inflammatory processes involving the eye and its adnexa such as: ... Optic neuritis Optic neuritis is an inflammatory process involving the optic nerve. 2

From the Research

Definition and Overview of Optic Neuritis

• Optic neuritis (ON) is an acute inflammatory demyelinating disorder of the optic nerve that occurs most often in young adults 3.
• It can be a monophasic or polyphasic disease isolated to the optic nerve(s) or can be associated with a more widespread demyelinating disorder of the central nervous system such as multiple sclerosis (MS) or neuromyelitis optica 3, 4.
• ON usually presents with acute unilateral visual loss associated with ocular pain exacerbated by eye movements 3.

Clinical Presentation and Diagnosis

• Optic neuritis is a common clinical manifestation of central nervous system inflammation, and depending on the etiology, visual prognosis and the risk for recurrent injury may vary 5, 6.
• Early clinical recognition of optic neuritis is important in determining the potential aetiology, which has bearing on prognosis and treatment 4.
• Clinical clues, examination findings, neuroimaging, and laboratory testing can differentiate autoimmune, granulomatous, demyelinating, infectious, and paraneoplastic causes of optic neuritis 5.

Treatment and Management

• Advances in therapeutics that modify the risk of progression to MS have emphasized accurate diagnosis and risk assessment of patients with ON 3.
• Intravenous methylprednisolone accelerates visual recovery from ON but has no impact on long-term visual outcome 3.
• Disease modifying drugs, in particular interferons-beta, have been shown to reduce the risk of MS conversion in high-risk patients presenting with a CIS, such as ON 3.
• Guided by early and accurate diagnosis of optic neuritis subtypes, the timely use of high-dose corticosteroids and, in some instances, plasmapheresis could prevent loss of high-contrast vision, improve contrast sensitivity, and preserve colour vision and visual fields 4.
• However, there is no conclusive evidence of benefit in terms of recovery to normal visual acuity, visual field or contrast sensitivity with either intravenous or oral corticosteroids at the doses evaluated in trials included in this review 7.

Prognosis and Outcome

• The visual prognosis is excellent in most cases regardless of whether the patient is treated with corticosteroids or not 3, 6.
• Regaining high-contrast visual acuity is common in people with idiopathic optic neuritis and multiple sclerosis-associated optic neuritis; however, residual deficits in contrast sensitivity, binocular vision, and motion perception might impair vision-specific quality-of-life metrics 4.
• Recovery of visual acuity can be poorer and optic nerve atrophy more severe in individuals who are seropositive for antibodies to myelin oligodendrocyte glycoprotein, AQP4, and CRMP5 than in individuals with typical optic neuritis from idiopathic or multiple-sclerosis associated optic neuritis 4.