1.2a Disorders of the Optic Nerve

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BEI SAMONTE☺ Page 1 of

1 2A DISORDERS OF THE OPTIC NERVE

OPHTH LMOLOGY

OUTLINE

1. Anatomy of the Optic Nerve

2. Evaluation of Patients with Optic Nerve Disorders

3. Optic Nerve Disorders

ANATOMY

1. Optic nerve

2. Optic chiasma

3. Optic tract

4. Lateral geniculate body

5. Optic radiation

6. Visual cortex

7. Superior colliculus of the midbrain

8. Putamen

9. Long association bundle - inferior occipitofrontal fasciculus

10. Pulvinar of the thalamus

11. Calcarine fissure

12. Posteroinferior horn of the lateral ventricle









Ophthalmology

Variable results in patients with optic neuritis. Note the variation from

near normal to near complete hemianopia (Reproduced with permission

of the American Medical Association. From Wall et al.[14] Copyright ©

1998. American Medical Association. All rights reserved.)

ANCILLARY TEST: OTHERS

• Color vision test

• Contrast sensitivity

• Visual evoked response

• Imaging studies

– Ultrasound

– CT scan

– MRI

OPTIC NERVE DISORDERS

• Papilledema

• Optic neuritis

• Anterior ischemic optic neuropathy

• Toxic optic neuropathy

• Optic atrophy

• Leber hereditary optic neuropathy

PAPILLEDEMA

• Swelling of optic nerve head secondary to raised CSF pressur

• Causes:

– Brain tumors, intracranial trauma, meningitis,

hydrocephalus, subarachnoidal hemorrhage, etc

Visual field defects in idiopathic intracranial hypertension. (a) Enlarged

blind spot. (b) Nasal step. (c) Biarcuate scotoma. (d) Severe visual field

constriction

• Almost always bilateral

• Severity α increase in intracranial pressure

• Enlargement of physiologic blind spot = early VF defect

• Treatment is directed in the underlying cause

• If untreated, will lead to optic atrophy and permanent visual

loss





Ophthalmology

OPTIC NEURITIS

• Inflammatory edema of the optic

nerve

• Foremost symptom: severe

visual loss

• Eye pain aggravated by eye

movement

• Usu. Unilateral

• RAPD detected

• Swollen hyperemic optic disc

with blurred margins

− Papillitis: localized anterior to

optic disc

− Retrobulbar neuritis: posteriorly

behind eyeball

− neuroretinitis : extended to the

adjacent retina

• Demylenating etiology is always

considered, like MS

• Meticulous neurologic history and exam is mandatory Color

photograph of a patient with acute anterior

optic neuritis (papillitis)

• Spontaneous resolution of visual loss may occur

• Corticosteroid preferably given IV may shorten clinical course

CLASSIFICATION OF OPTIC NEURITIS

Retrobulbar neuritis

(normal disc)

Papilitis (hyperaemia

& edema)

Neuroretinitis

(papillitis and macular

star)

• Demyelination -

most common

• Sinus-related

(ethmoiditis)

• Lyme disease

• Viral infections and

immunization in

children (bilateral)

• Demyelination

(uncommon)

• Syphilis

• Cat-scratch fever

• Lyme disease

• Syphilis

ANTERIOR ISCHEMIC OPTIC NEUROPATHY

• Sudden painless, non-progressive blurring of vision in patients

over 50 years of age

• Occlusion of the posterior ciliary arteries resulting to optic disc

edema and altitudinal field defect

– Non-arteritic: HTN, DM, dyslipedemia, coronary hea

disease; mngt is directed towards the predisposing

medl problem

– Arteritic (less common): temporal and giant cell

arteritis; steroids is necessary

NON-ARTERITIC AION

• Presentation

- Age: 45 to 65 years

- Altitudinal field defect

- Eventually bilateral in 30% (give aspirin)

• Affects about 25% of untreated patients with giant cell arterit

• Severe acute visual loss

• Treatment - steroids to protect fellow eye

• Bilateral in 65% if untreated

ACUTE SIGNS LATE SIGNS

• Pale disc with diffuse or

sectorial oedema

• Few, small splinter-shaped

haemorrhages

• Subsequent optic atrophy

• Resolution of oedema and

haemorrhages

• Optic atrophy and variable

visual loss

FA in acute non-arteritic AION

Localized hyperfluorescence Increasing localized Generalized hyperfluorescen

hyperfluorescence

SUPERFICIAL TEMPORAL ARTERITIS

• Presentation

- Age: 65 to 80 years

- Scalp tenderness

- Headache

- Jaw claudication- Polymyalgia rheumatica

- Superficial temporal arteritis

- Acute visual loss

• Special investigations

- ESR - often > 60, but normal in 20%

- C-reactive protein - always raised

- Temporal artery biopsy



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Ophthalmology

HISTOLOGY OF GIANT CELL ARTERITIS

• Granulomatous cell infiltration

• Disruption of internal elastic

lamina

• Proliferation of intima

• Occlusion of lumen

• High-magnification shows

giant cells

TOXIC OPTIC NEUROPATHY

• Symptoms

- Diminution of vision: bilaterally symmetrical, painless,

gradually progressive

- Dyschromatopsia

• Signs- Pupils: sluggish, no RAPD

- Optic disc: normal, swollen, or hyperemic in early stages;

temportal optic disc pallor later

- Visual field defect: centrocaecal scotoma

THE MOST COMMON CAUSES OF TOXIC OPTIC NEUROPATHY

• Tobacco / ETOH amblyopia

• Antitubercular drugs: Ethambutol, Isoniazid, Streptomycin

• Chloramphenicol

• Chlorpropamide

• Disulfiram

• Arsenic

• Heavy metals: Lead. mercury, Thallium

• Alcohols: Methanol, ethylene glycol (antifreeze)

• Antiarrhythmic agents: Digitalis, Amiodarone

• Antimalarials: Chloroquine / Quinine

• Radiation

• Antibiotics: Chloramphenicol, sulfonamides, linezolid

• Anticancer agents: Vincristine, methotrexate

• Others: Carbon monoxide, tobacco

Disc pallor in a 44-year-old female with ethambutol toxicity.

She was treated with ethambutol for 2 months for tuberculoma

brain.

OPTIC ATROPHY

• A result of a severe long standing damage or injury to the opti

nerve

• Pallor optic disc = Degeneration of the nerve axons

• Leads to vision loss and poor prognosis



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Ophthalmology

LEBER HEREDITARY OPTIC NEUROPATHY

• Maternal mitochondrial DNA

mutations

• Presents:

- Typically in males - third decade

- Occasionally in females - any age

- Initially unilateral visual loss

- Fellow eye involved within 2 months

- Bilateral optic atrophy

• Signs:

- Disc hyperaemia and dilated capillaries

(telangiectatic microangiopathy)

- Vascular tortuosity

- Swelling of peripapillary nerve fibre layer

END OF TRANX

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1.2a Disorders of the Optic Nerve