optic neuritis

Optic neuritis=INFLAMMATION,INFECTION OR

DEMYELINATION OF OPTIC NERVE

Optic Neuritis - Outline

• Definition

• Classification

▫ Ophthalmoscopic

▫ Aetiological

• Clinical Features

• Investigations

• Principle of Management

CLASSIFICATION:

Can be classified both ophthalmoscopically and

etiologically:

Retrobulbar neuritis

Papillitis (most common)

Neuroretinitis

Demyelinating **

Parainfective

(rubella,mumps&chicken pox)

Infective

(sinusitis.syphilis,cat-scratch fever)

Autoimmune

OPHTHALMOSCOPICALLY

ETIOLOGICALLY

• Retrobulbar neuritis

Optic nerve is affected more posteriorly with no disc swelling.

• Papillitis

Affect optic nerve head (hyperaemia & oedema of optic disc) +

peri-papillary flame-shaped haemorrhages

• Neuroretinitis

Characterized by papillitis with inflammation of the retinal nerve

fiber layer. A macular star figure composed of hard exudates

may present. Least common and most frequently associated with

viral infections and cat-scratch fever, Syphilis and Lyme disease.

Usually self-limiting which resolves 6-12 months.

Neuroretinitis is rarely a manifestation of demyelination.

Ophthalmoscopical Classification

Retrobulbar neuritis Papillitis Neuroretinitis

Optic nerve affected behind the eyeball

Optic nerve head affected Concomitant swelling of optic nerve head (papillitis) and macula (inflammation of retinal nerve fibre layer)

The optic disc appears normal

The condition may be truly described as ‘ the patient sees nothing and the doctor sees nothing.’

Hyperaemia and oedema of the optic disc

May be a/w peripapillary flame-shaped haemorrhages

Macular star (exudates that form around the macula give the appearance of the star)

Most frequent type in adults

Frequently a/w multiple sclerosis (MS)

Most common type in children

Least common type Rarely a manifestation of

demyelination Due to viral infection,cat-

scratch fever

Normal optic disc, primary optic atrophy. The condition may be truly described as ‘ the patient sees nothing and the doctor sees nothing.’

Retrobulbar neuritis

swollen disc with blurring and hyperaemia of disc margin; venous dilation and engorgement ; vitreous haziness because of inflammatory exudates and cells that invaded the vitreous( mild vitritis); Flame-shaped hemorrhages and cotton wool spot (soft exudates) on and around the disc; secondary optic atrophy

Papillitis

Macular star

(Exudates in a star-shaped pattern radiating from the macula)

Neuroretinitis

Diffuse Unilateral Subacute

Neuroretinitis - Nematode

Aetiological Classification (causes)

1. Demyelinating Pathological process: the normally myelinated nerve fibres lose

their insulating myelin layer (The myelin is phagocytosed by microglia and macrophages,subsequent to which astrocytes lay down fibrous tissue (plaque) -> distrupts nerve conduction w/in white matter tracts( brain,brainstem,spinal cord)

Ages: 20-50 years old, F:M = 3:2

Most common cause (eg. Multiple sclerosis)

Optic disc is normal (retrobulbar neuritis)

DEMYLINATING DISEASE CAUSES OCULAR PROBLEMS:

1. Isolated optic neuritis

2. Multiple sclerosis

3. Devic disease (neuromyelitis optica) : bilateral optic neuritis -> transverse

myelitis

4. Schilder disease : bilateral; progressive generalised disease (onset prior to

10y/o death within 1-2yrs)

a) visual p/way-> lesion commonly involve optic nerves and cause optic

neuritis

b) Brainstem-> lesions result in gaze palsies, ocular motor cranial nerve

palsies, trigeminal , facial nerve palsies and nystagmus

Multiple sclerosis (MS)

• A remitting idiopathic

demyelinating disease in CNS

• Autoimmune rxn : T-cell

activation => attack&destruct

myelin

2. Parainfectious

Common in children

Occurs d/t exposure of antigens of certain infectious agents eg. measles, mumps, chickenpox, rubella,whoopingcough,glandular fever

Following viral infection, immunization

Usually 1-3 weeks following viral infection with acute severe

visual loss

Usually bilateral papillitis occur

(occasionally: neuroretinitis or the discs may be normal)

Spontaneous recovery within few weeks

May be a/w other neurological features eg. headache, seizures or ataxia (meningoencephalitis)

3. Infectious

Sinus-related optic neuritis

a/w Cat-scratch fever, syphilis, Lyme disease, cryptococcal

meningitis in patients with AIDS and herpes zoster.

4. Non-infectious

Sarcoidosis- optic nerve head exhibit lumpy appearance,

inflammatory reaction in vitreous

Systemic autoimmune diseases –retrobulbar neuritis

eg. SLE, polyarteritis nodosa, other vasculitides (vasculitis)

Clinical Features of Optic Neuritis

Clinical Presentations

• Usu. women aged btw 20-40 (mean around 30 years)

• Acute unilateral loss of vision, may progress over a few days,

then slowly improve

• Pain exacerbated on eye movement (retrobulbar neuritis) b/c rectus

contraction pulls on the optic nerve sheath; painless (papillitis)

• Dyschromatopsia (change in color perception) in affected eye

• Flashes of light/ phosphenes (tiny white or coloured flashes or

sparkles) induced by eye movement or loud sounds

• Relapsing( most common)/ Progressive (10%)

• A preceding H/O viral illness in some cases

• Vision loss exacerbated by heat or exercise (Uhthoff

phenomenon).

• 40-70% of patients will have other neurological symptoms

(such as parasthesia, weakness, incontinence, Lhermitte sign)

to suggest a diagnosis of demyelination (multiple sclerosis)

Examinations

• Reduced visual acuity

• Reduced color vision

• RAPD (Relative afferent pupillary defect) : reduced

optic nerve conduction

• Central scotoma

• Normal disc: retrobulbar neuritis ; Swollen disc:

papillitis

Diagnosis

• The diagnosis of optic neuritis is clinical, based on the history

and physical findings.

• Investigations

▫ Brain MRI

▫ Serological tests: ESR, syphilis, antinuclear antibody

(ANA), antineutrophil cytoplasmic antibodies (ANCA)

▫ CSF analysis (lumbar puncture) : Presence of oligoclonal

band, elevated IgG level suggest MS.

Brain MRI

• MRI of the brain and orbits with gadolinium contrast has

become the cornerstone of the evaluation in patients with optic

neuritis

▫ To confirm the clinical diagnosis (look for additional

plaques of demyelination)

▫ Offers very strong prognostic information about the risk of

future demyelinating events and MS

▫ For treatment decision

A gadolinium-enhanced fat-saturated T1-weighted scan will show a bright enhancement of the inflamed optic nerve (upper left red arrow). Additionally, bright spots characteristic of multiple sclerosis may also be seen in the brain (lower right red arrow).

White matter lesions in

brain MRI denote a higher

risk of developing MS

Principle of Management

TREAT THE

UNDERLYING

CAUSE

Management: Demyelinating Optic

Neuritis

• In most cases (mild vision loss, no significant visual field

loss, no enhancing lesions on brain MRI) - no treatment

• Vision slowly recovers over several weeks even w/o treatment

(spontaneously)

• Treatment Indicated

▫ Visual acuity worsen than 6/12

▫ Treatment hasten the recovery process, but no effect on

long-term visual outcome

Regimen

▫ IV corticosteroid (eg. methylprednisolone)

1g daily for 3 days followed by oral steroid as prednisone

(1mg/kg/day) for 11 days and then tapered for 3 days

▫ IM interferon beta-1a

Reducing the development of clinical MS over the

following 3 years in patients at high risk (based on the

presence of subclinical brain MRI lesion)

NB. Oral prednisolone alone is contraindicated b/c it does not affect

the speed of recovery and is a/w a significantly higher recurrence rate.

Corticosteroids S/E

• Mood changes

• Facial flushing

• Weight gain

• Dyspepsia