Optic neuritis

# Historical Perspective

## Discovery
- Optic neuritis was first discovered by von Graefe and Nettleship, in late nineteenth century when ophthalmoscopy became part of the ophthalmic examination.
- The association between systemic sclerosis and optic neuritis was made by the early 1900's but there was much controversy and misunderstanding about its differential diagnosis, pathogenesis, and possible treatment.
- Optic neuritis was first distinguished from infectious,hereditary, toxic, nutritional, and ischemic optic neuropathies during the twentieth century.
- During late twentieth century, the development of MRI and the results from recent clinical trials, discovered the relationship between optic neuritis and multiple sclerosis.

# Classification
Optic neuritis may be classified into atypical or typical subtypes based on its clinical features.
- Atypical optic neuritis entails clinical manifestations that deviate from classic pattern of optic neuritis features.
- Atypical features to consider include:
Lack of pain
Simultaneous or near-simultaneous onset
Lack of response to or relapse upon tapering from corticosteroids
Optic neuritis due nerve head or peripapillary hemorrhages
- Lack of pain
- Simultaneous or near-simultaneous onset
- Lack of response to or relapse upon tapering from corticosteroids
- Optic neuritis due nerve head or peripapillary hemorrhages

# Pathophysiology

## Pathogenesis
- The exact pathogenesis of optic neuritis is not completely understood.
- But It is likely due to some inflammatory process which leads to delayed type IV hypersensitivity reaction induced by released cytokines and other inflammatory mediators from activated peripheral T-cells which can cross the blood brain barrier and cause destruction of myelin, neural cell death and axonal degeneration.
- In addition to involvement of the myelin sheath (white matter), latest technologies such as optical coherence tomography (OCT) suggest involvement of axons (gray matter) in this process.
- Findings suggestive of optic neuritis in microscopic histopathological analysis include:
Reduced axon counts
Optic atrophy
Inflammation
Demyelination
Axonal loss
Intracellular neurofilaments
- Reduced axon counts
- Optic atrophy
- Inflammation
- Demyelination
- Axonal loss
- Intracellular neurofilaments

# Causes
- The exact cause of optic neuritis is unknown.
- But It is likely due invasion of the immune system to the myelin, resulting in inflammation and damage to the myelin.
The following autoimmune are associated with optic neuritis:
- Multiple sclerosis:
Multiple sclerosis is the first main cause of optic neuritis.
50% of patients with multiple sclerosis finally develop optic neuritis.
- Multiple sclerosis is the first main cause of optic neuritis.
- 50% of patients with multiple sclerosis finally develop optic neuritis.
- Neuromyelitis optica
In Neuromyelitis optica, inflammation recurs in the optic nerve and spinal cord.
- In Neuromyelitis optica, inflammation recurs in the optic nerve and spinal cord.
- Infections:
Lyme disease
Cat-scratch disease
Syphilis
Measles
Mumps
Herpes simplex
- Lyme disease
- Cat-scratch disease
- Syphilis
- Measles
- Mumps
- Herpes simplex

# Differentiating Optic Neuritis from other Diseases
Optic neuritis must be differentiated from other diseases that cause sudden eye pain and vision loss such as:
- Lebers Hereditary Optic Neuropathy (LHON) which results from point mutations in mitochondrial DNA and subsequent mitochondrial dysfunction, causing bilateral central vision loss.
- Nonarteritic Anterior Ischemic Optic Neuropathy (AION)
It is the most common form of ischemic optic neuropathy and the second most common optic neuropathy.
It is more common in patients over the age of 50 years with vasculopathic risk factors such as:
Diabetes mellitus
Hypertension
Obstructive sleep apnea
- It is the most common form of ischemic optic neuropathy and the second most common optic neuropathy.
- It is more common in patients over the age of 50 years with vasculopathic risk factors such as:
Diabetes mellitus
Hypertension
Obstructive sleep apnea
- Diabetes mellitus
- Hypertension
- Obstructive sleep apnea

# Epidemiology and Demographics

## Incidence
- The incidence of optic neuritis is approximately 5 to 6.4 per 100 000 individuals in US.

## Age
- Optic neuritis commonly affects patients between the ages of 15 and 49.

## Race
- Optic neuritis usually affects individuals of the Caucasians race eight times more frequently than Blacks and Asians.
- Black populations individuals are less likely to develop optic neuritis.

## Gender
- Women are more commonly affected by optic neuritis than men.

## Region
- The incidence of optic neuritis is highest in populations located at higher latitudes such as:
Northern United States
Northern and Western Europe
New Zealand and Southern Australia
- Northern United States
- Northern and Western Europe
- New Zealand and Southern Australia

# Risk Factors

## Common Risk Factors
- Common risk factors in the development of optic neuritis include:
Age
Optic neuritis most often affects adults between the ages of 15 and 49.
Sex
Women are much more likely to develop optic neuritis than men are.
Race
Optic neuritis usually affects individuals of the Caucasians race eight times more frequently than Blacks and Asians.
Black populations individuals are less likely to develop optic neuritis.
Genetic mutation
Multiple sclerosis
Trauma
Nutritional deficiencies
Compression of the optic nerve
Arteritic optic neuropathy
Diabetes
Glaucoma
- Age
Optic neuritis most often affects adults between the ages of 15 and 49.
- Optic neuritis most often affects adults between the ages of 15 and 49.
- Sex
Women are much more likely to develop optic neuritis than men are.
- Women are much more likely to develop optic neuritis than men are.
- Race
Optic neuritis usually affects individuals of the Caucasians race eight times more frequently than Blacks and Asians.
Black populations individuals are less likely to develop optic neuritis.
- Optic neuritis usually affects individuals of the Caucasians race eight times more frequently than Blacks and Asians.
- Black populations individuals are less likely to develop optic neuritis.
- Genetic mutation
- Multiple sclerosis
- Trauma
- Nutritional deficiencies
- Compression of the optic nerve
- Arteritic optic neuropathy
- Diabetes
- Glaucoma
- Common risk factors in the recurrence of optic neuritis include:
Underlying diseases such as:
Neuromyelitis optica
Multiple sclerosis
Unilateral optic neuritis
Early initiation of glucocorticoid
- Underlying diseases such as:
Neuromyelitis optica
Multiple sclerosis
- Neuromyelitis optica
- Multiple sclerosis
- Unilateral optic neuritis
- Early initiation of glucocorticoid

# Natural History, Complications and Prognosis

## Natural History
- The symptoms of optic neuritis usually develop in the second decade of life, and start with symptoms such as pain on movement of the eyes, followed by a worsening of vision.
- Common symptoms of optic neuritis include:
Pain on movement of the eyes which is sever and so disturbing
Seeing things darkly, unclearly, and with poor contrast
Dirty and pale Colors
Visual field loss
Disturbed color vision
Flashing lights
- Pain on movement of the eyes which is sever and so disturbing
- Seeing things darkly, unclearly, and with poor contrast
- Dirty and pale Colors
- Visual field loss
- Disturbed color vision
- Flashing lights
- After a sub acute onset, the patients visual acuity continues to deteriorate for a few more days; in the untreated course of the disease, it generally reaches its nadir in one to two weeks and then improves again.

## Complications
- Common complications of optic neuritis include:
Side effects of corticosteroids use
Permanent optic nerve damage
Decreased visual acuity
In some cases of optic neuritis, partial loss of color discrimination might persist.
- Side effects of corticosteroids use
- Permanent optic nerve damage
- Decreased visual acuity
In some cases of optic neuritis, partial loss of color discrimination might persist.
- In some cases of optic neuritis, partial loss of color discrimination might persist.

## Prognosis
- The long-term visual prognosis of idiopathic optic neuritis is generally good.
- More than 90% of the patients recover a visual acuity of 20/40 or better by 6 months.
- Findings associated with poor visual outcome at 6 months include:
A cut-off level of vision  20/50
Contrast sensitivity of <1.0 log units
A visual field mean deviation of   15 dB after 1 month in the Optic Neuritis Treatment Trial.
- A cut-off level of vision  20/50
- Contrast sensitivity of <1.0 log units
- A visual field mean deviation of   15 dB after 1 month in the Optic Neuritis Treatment Trial.
- Despite the relatively good visual outcome, most patients show a degree of long-lasting damage to the optic nerve, such as:
A pale optic disc
Loss of retinal nerve fibers
Prolonged latency in the visual evoked response
Thinning of the optic nerve on MR
- A pale optic disc
- Loss of retinal nerve fibers
- Prolonged latency in the visual evoked response
- Thinning of the optic nerve on MR

# Diagnosis

## Diagnosis studies
The diagnosis of typical optic neuritis is usually made clinically.
The classic triad for diagnosis of optic neuritis consist of:
- Visual loss
- Periocular pain
- Dyschromatopsia
MRI is the diagnosis study of choice for visualising the optic nerve.
The following result of MRI is confirmatory of optic neuritis:
- Swollen retrobulbar intra-orbital segment of the optic nerve with a high T2 signal. High T2 signal persists and may be permanent;
- Atrophied nerve in chronic cases
Other diagnosis studies which may help to diagnosis of optic neuritis include:
- Functional MRI
- Multifocal visual evoked potential
- Optical coherence tomography (OCT)

## Symptoms
- The symptoms of optic neuritis usually develop in the second decade of life, and start with symptoms such as pain on movement of the eyes, followed by a worsening of vision.
- Common symptoms of optic neuritis include:
Pain on movement of the eyes which is sever and so disturbing
Seeing things darkly, unclearly, and with poor contrast
Dirty and pale Colors
Visual field loss
Disturbed color vision
Flashing lights
- Pain on movement of the eyes which is sever and so disturbing
- Seeing things darkly, unclearly, and with poor contrast
- Dirty and pale Colors
- Visual field loss
- Disturbed color vision
- Flashing lights
- After a sub acute onset, the patients visual acuity continues to deteriorate for a few more days; in the untreated course of the disease, it generally reaches its nadir in one to two weeks and then improves again.

## Physical Examination
Physical examination of patients with optic neuritis is usually remarkable for:
- Ophthalmic examination findings:
Papillitis with swollen optic disc
Normal optic disc appearance (2/3 of cases) in retrobulbar neuritis type of optic neuritis
Perineuritis, which involves the optic nerve sheath while the optic disc may or may not be swollen
Neuroretinitis with optic disc oedema and macular star exudates
- Papillitis with swollen optic disc
- Normal optic disc appearance (2/3 of cases) in retrobulbar neuritis type of optic neuritis
- Perineuritis, which involves the optic nerve sheath while the optic disc may or may not be swollen
- Neuroretinitis with optic disc oedema and macular star exudates
- Unilateral loss of visual acuity
- Reduced contrast sensitivity
- Ipsilateral relative afferent pupillary defect
- Visual field defect
- Dyschromatopsia

## Laboratory Findings
- There are no specific diagnostic laboratory findings associated with optic neuritis.
- If multiple sclerosis is suspected, extensive laboratory testing is recommended in the neurologic guidelines.
- Other recommended laboratory tests for all patients with optic neuritis include:
C-reactive protein
Complete blood count
Serum chemistry
Blood sugar
Vitamin B12
Rheumatoid factor
Antinuclear antibodies
Anti-phospholipid antibodies
Anti-ds-DNA antibodies
Lupus anticoagulant
Serum angiotensin-converting enzyme test
Borrelia serology
Urinalysis
- C-reactive protein
- Complete blood count
- Serum chemistry
- Blood sugar
- Vitamin B12
- Rheumatoid factor
- Antinuclear antibodies
- Anti-phospholipid antibodies
- Anti-ds-DNA antibodies
- Lupus anticoagulant
- Serum angiotensin-converting enzyme test
- Borrelia serology
- Urinalysis

## Imaging Findings
Among all imaging studies, MRI is the diagnosis study of choice for visualising the optic nerve.
The following result of MRI is confirmatory of optic neuritis:
- Swollen retrobulbar intra-orbital segment of the optic nerve with a high T2 signal. High T2 signal persists and may be permanent;
- Atrophied nerve in chronic cases
Other diagnosis studies which may help to diagnosis of optic neuritis include:
- Functional MRI
- Multifocal visual evoked potential
- Optical coherence tomography (OCT)

## Other Diagnostic Studies
There are no widely used other diagnosis studies for diagnosis of optic neuritis.

# Treatment

## Medical Therapy
Optic neuritis requires prompt treatment.
The mainstay of treatment for optic neuritis is corticosteroid therapy and is recommended among all patients who develop optic neuritis.
Some pharmacologic medical therapies for optic neuritis include:
- Oral prednisone treatment at a dose of 1 mg/kg body weight /day for 14 days
- intravenous methylprednisolone treatment at 5001000 mg/day for 3_5 days followed by oral prednisolone (1 mg/kg BW) for 11 days

## Surgery
- In the case of optic canal compression in patients with severe optic neuritis, surgery is used to decompress the orbital compartment by exposure of the intracanalicular part of the optic nerve.
- Modern craniomaxillofacial surgery requires detailed consideration of the diagnosis and treatment of traumatic visual pathway damage with the ultimate goal of preserving visual acuity.

## Prevention
There are no established measures for the primary prevention of optic neuritis.