optic nerve and optic nerve lesions

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OPTIC NERVE +

OPTIC NERVE LESIONS

Robert William B. King, MD

May 09, 2015

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ANATOMY Begins:

Optic disc (Anatomically) Ganglion cells of retina (physiologically)

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ANATOMYFirst part of ON

Approx. 1.0-1.2 M ganglion cells

Axons travers the sclera through lamina cribrosa (200-300 channels)

1mm Sheathed with dura and myelin coating once posterior the sclera

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ANATOMY Intraorbital

Extends approx. 25-30mm to the optic canal

Intracanalicular Approx 4-10mm

Intracranial 10-20mm

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LESIONS

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PAPILLEDEMASwelling of the optic disc from increased intracranial pressure

Headache is usual (worse in morning)An alarming signResults from axoplasmic flow stasis of the optic nerve head

Can result in loss of axons, and eventual atrophyDevelops anywhere from <24hrs to weeks

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PAPILLEDEMA CAUSESSpace occupying lesion (tumor, hemorrhage)Decreased CSF drainaige or absorption (obstructive hydrocephalus / infection, hemorrhage, thrombosis)

Idiopathic intracrainial hypertension (Pseudotumor cerebri)

Increased CSF production (choroid plexus tumor)Decreased skull volume (craniosynostosis)

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Must be distinguished from:Edema of other causePseudo papilledema (disc drusen)Papillitis

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DIAGNOSISFundus exam - noting disc swelling (usually bilateral unless one is atrophic)

Fluorescein AngiographyPerimetry (enlarged blind spots)CT or MRI (preferred) (can be noted as flattening of the sclera near optic nerve + raised area at disc head)

Lumbar puncture

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Fast-spin echo T2-weighted axial imaging demonstrated reversed optic nerve cupping in the right eye with posterior scleral flattening and protrusion of optic nerve papilla into the globe (arrow) 

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PAPILLITIS Inflammation or infarct of the optic nerve head Usually unilateral (+) Visual abnormalities (color, VA) Optic nerve head swelling Disc hemorrhages Causes:

Optic neuritis Multiple sclerosis Infarct or nerve head

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PAPILLEDEMA VS PAPILLITISPapilledema Papillitis

Definition Due to raised intracranial pressure

Inflammation of the optic nerve head

Laterality Bilateral Unilateral

Cause Increase in ICP Optic neuritis, multiple sclerosis, infarct

Vision loss Not usual COMMON (cardinal symptom)

Color perception Unchanged Depressed

RAPD No Yes

Hemorrhages Around disk Periphery of disc or on disc

Treatment Decrease ICP (depending on cause)

Usually high dose steroids

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WHICH IS WHICH?Papillitis Papilledem

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OPTIC DISC DRUSEN “Pseudopapilledema” Consist of refractive, hyaline-like calcified nodules located within the optic nerve head

May be due to slowed axoplasmic flow Prevalence 0.4-3.7% Males = Females Whites > Blacks >85% bilateral, but asymmetric Familial – Autosomal dominant inheritance

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OPTIC DISC DRUSEN Composed of small proteinaceous material that become calcified with advancing age.

May lead to an elevated disc (and therefore pseudopapilledema). 

Usually asymptomatic, but may lead to a loss of visual field or, in rare cases, central acuity. 

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Elevated optic disc, with small contour

Indistinct and irregular disc margins

Anomalous vascular branching pattern (tortousity, optociliary shunt vessels)

Drusen seen as round, white/yellow refractile bodies on the surface of the nerve or buried beneath it

Nasal margin is most common site of drusen

Spontaneous venous pulsations often seen

Afferent pupillary defect if there is asymmetric nerve involvement

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TREATMENT No treatment necessary (normal physiologic variant)

Visual prognosis for is generally good

Currently no effective treatment for patients that have gradual loss of visual fields

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TRAUMATIC OPTIC NEUROPATHY (TON) Most common cause: Indirect injury to the optic nerve

85% of patients are male, ave age of 34 (International Optic Nerve Trauma Study)

Symptoms: Decreased central visual acuity Depressed color vision RAPD Visual field deficits

Signs The optic nerve head will appear normal initially, but optic atrophy can be seen

3-6 weeks after the initial traumatic event.

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History: A history consistent with TON

Vision loss after blunt or penetrating trauma that could not be explained by slit lamp or dilated fundus findings.

Often, patients complain of acute unilateral decrease in vision, color vision deficits, or visual field deficits.

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PATHOPHYSIOLOGY OF TON

The optic nerve dura is continuous with the orbital periosteum, leaving the optic nerve susceptible to transmission of force from blunt head trauma.

Indirect TON - result from shearing injury to the intracanalicular portion of optic nerve, which can cause axonal injury or disturb the blood supply of the optic nerve.

Direct TON - tissue disruption secondary to foreign body or bony fragments impacting on the optic nerve.

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PROGNOSIS Visual acuity improvement of >3 lines was seen in 57% of patients

Use of steroids did not result in significant difference in outcome

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ARTERITIC ANTERIOR ISCHEMIC OPTIC NEUROPATHY (AAION) Acute and painless optic neuropathy Decreased visual acuity - tipically severe (<20/200 in over 60% of the patients)

May occur as ocular manifestation of giant cell arteritis (5-10% of cases)

Predominantly in patients over 70 years old

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PATHOGENESIS Inflammatory and thrombotic involvement of the short posterior ciliary arteries (SPCA’s) with resultant optic nerve head infarction

Ischemia occurs at the head of the optic nerve in relation with structural crowding of the nerve fibers and reduction of the vascular supply impairing perfusion and producing optic disc edema.

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DIAGNOSIS Severe visual acuity loss

(+) RAPD

Pallor of the optic disc, which may be severe, chalky-white is the hallmark of AAION

Narrowed peripapillary arterioles

Diffuse disc swelling

Extremely poor or absent filling of the choroid has been depicted as a characteristic of AAION

Elevated ESR and/or CRP

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TREATMENT Early treatment is essential.

High dose systemic corticosteroid are standard.

IV methylprednisolone at 1g/day for the first 3 days has been recommended for severe cases.

Oral prednisone in the range of 60-100mg/day may be used initially and for follow up to intravenous pulse therapy.

Treatment is usually continued at a high dose for a several months before beginning taper.

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PROGNOSIS Without treatment, visual loss occurs in 54-95%, typically within 4 months. Reduced to 13% if with corticosteroid therapy.

Despite treatment, visual recovery of the affected eye is poor with a 15-34% improvement rate.

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NON-ARTERITIC ANTERIOR ISCHEMIC OPTIC NEUROPATHY (NAION) Acute painless visual loss

Most common cause of acute optic neuropathy in patients over the age of 50

Pathology is unclear, but it is presumed to result from a circulatory insufficiency

Leads to a compartment syndrome from axonal edema in a structurally crowded optic disc

Up to 97% of patients with NAION have small optic discs with small or absent optic cups

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Signs: Some or all of the signs of an optic neuropathy Decreased visual acuity (NLP very rare) Dyschromatopsia RAPD Swollen optic nerve Splinter Hemorrhages Visual field defects (altitudinal field loss [inferior most common], central

scotoma)

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DIAGNOSTICS ESR

CRP

Temporal artery biopsy is recommended to rule out GCA and AAION

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TREATMENT There is no effective treatment for NAION

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PROGNOSIS Vision can worsen over 2 weeks after initial presentation Natural history of visual outcome showed approximately 50% of patients had a visual acuity of 20/30 or better and nearly one-quarter were 20/200 or worse.

Vision in the affected eye will typically stabilize within two months Progression or recurrence more than two months after initial presentation should bring the diagnosis of NAION into question

Recurrence in the affected eye range from 3% to 8% Involvement of the fellow eye ranges from 15% to 24% over 5 years

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POSTERIOR ISCHEMIC OPTIC NEUROPATHYAcute Retrobulbar portion of ONSever vision loss (+) RAPD Initially optic discs are normalDiagnosis of exclusion (rare)Prognosis: Poor

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DIABETIC PAPILLOPATHY Occurs in both DM type 1 or 2

No symptoms or have nonspecific symptoms of"blurred vision'' or "distortion" without pain

The optic nerve reveals hyperemic edema

VA and RAPD are variable

50% with marked dilation of the disc surface microvasculature appearing similar to neovascularization of the disc (NVD)

The absence of DM retinopathy does not preclude a diagnosis of diabetic papillopathy

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PROGNOSIS resolve slowly over 2-l 0 months. Optic atrophy occurs in 20% of cases, but

the visual

Prognosis often depends mostly upon the degree of accompanying diabetic retinopathy.

Rarely, diabetic papillopathy progresses to AION, with residual pallor and nerve fiber defects

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LEBER HEREDITARY OPTIC NEUROPATHY (LHON) Males 10-30 y/o

Mitochondrial DNA

Acute, severe, painless, sequential vision loss (visual acuity, <20/200) and central or cecocentral visual field impairment

Fundus Triad (AAO 2015):

1. Hyperemia and elevation of the optic disc, with thickening of the peripapillary retina; although the disc appears swollen, it does not leak on fluorescein angiography ("pseudoedema'')

2. Peripapillary telangiectasia 3. Tortuosity of the medium-sized retinal arterioles

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Hyperemic optic discs with blurred margins and moderately tortuous vasculature.

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TREATMENT No effective treatment

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PROGNOSIS Unaffected eye becomes symptomatic within weeks to months Vision loss is usually permanent Recovery of vision occur in 10%-20% of cases over several years

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AUTOSOMAL DOMINANT OPTIC ATROPHY (ADOA) Most common hereditary optic neuropathy (1:50,000)

Autosomal dominant

First decade of life

Insidious vision loss

Bilateral and symmetric

Color vision loss

No treatment available

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OPTIC NERVE HYPOPLASIA VA ranges from 20/15 to no light perception

BUT almost all have some degree of visual field loss

56-92% bilateral

The optic disc is small, usually one-half to one-third of normal diameter

Discs may be pale/grey or hyperemic (less common)

May be associated with endocrine abnormalities

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EXCAVATED OPTIC DISC ANOMALIESOptic pit –

Depression of the optic disc surface that is often gray or white,

Associated with a mild visual field

Serous detachment of the macula develops in 25%-75%

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EXCAVATED OPTIC DISC ANOMALIESColobomas -

Result from incomplete closure of the embryonic fissure

Usually occur inferiorly

Occasionally extend to the adjacent choroid and retina.

May have VF defects and RAPD depending on severity

Colobomas of other eye structures may be present

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EXCAVATED OPTIC DISC ANOMALIESMorning glory disc anomaly –

Funnel-shaped staphylomatous excavation of the optic nerve and peripapillary retina.

More common in females

Unilateral

(+) RAPD

Chorioretinal pigmentation surrounds the excavation, and white glial tissue is present on the central disc surface.

The characteristic feature: Radial spoke pattern of retinal vessels

Visual acuity can be normal, but is often 20/200 or worse

Retinal detachment is common

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POSTERIOR OPTIC NEUROPATHIES:RETROBULBAR OPTIC NEURITIS Typically in young females (30s)

Retrobulbar form occurs in 65% of cases

Disc appears normal

Subacute monocular visual loss

Periorbital pain, particularly with eye movement, occurs in 92%

(+) RAPD unless bilateral

Visual field loss

Dyschromatopsia (especially for red)

Some improvement after 1 month

Usually due to an isolated demyelinating event

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TREATMENT Corticosteroids failed to demonstrate long term benefit for visual acuity

Corticosteroids may speed up recovery by a few weeks

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NEUROMYELITIS OPTICA AKA Devic Syndrome

Optic neuritis and acute myelitis

Diagnostic Criteria (99% sensitivity 90% specificity): Optic neuritis Myelitis At least 2 of the ff:

Contiguous spinal cord lesion on MRI involving 3 or more vertebral segments Brain MRI nondiagnostic for MS Positive NMO-IgG serology

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TREATMENTMainstay treatment for acute period is high dose steroids IV

IV Ig or plasmapheresis can be done on patients who do not respond to steroids

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PROGNOSIS Visual prognosis for NMO patients are poorer vs MS

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OPTIC PERINEURITIS Inflammation of optic nerve sheathAcute painful vision lossFemale predilection Patients are generally older >50 y/oVision loss and pain progresses over weeks unless treate

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DIAGNOSIS Orbital MRI will show

enhancement of the dural sheath rather than optic nerve

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TREATMENT Responds rapidly to corticosteroids, but relapses are common

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INTRAORBITAL COMPRESSIVE OPTIC NEUROPATHYSlow progressive vision lossRAPDMonocular visual field loss (central of diffuse)Other signs of orbital disese

Proptosis Ptosis Retraction Lag Edema

Optic disc might be normal or with some edema

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MOST COMMON CULPRITSOptic nerve sheath meningiomaOptic nerve sheath glioma

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DIAGNOSISMRIThin section CT scan

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OPTIC NERVE SHEATH MENINGIOMA (ONSM)Proliferation of meningioepithelial cells of intraorbital and intracanalicular optic nerve

1/3 of primary optic nerve tumorsAdults aged 40-50Women > MenDiagnostic triad:

Painless slow monocular vision loss Optic atrophy Optociliary shunt vessels

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Optociliary shunt vessel preexisting optic disc channels that dilate due to chronic obstruction of outflow through the central retinal vein.

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Tram track sign

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Ring sign

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TREATMENTFractionated radiation therapy is the modality of choice for ONSMStability or improvement in vision up to 94.3% of patients

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OPTIC PATHWAY GLIOMA (OPG)Most common primary tumor of the optic nerve

May involve optic nerve, chiasm or bothFirst decade of lifeMen = Women

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DIAGNOSISProptosis (94%)Vision loss (87.5%)Optic dic pallor (59%)Disc edema (35%)Strabismus (27%)RAPD usually present

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DIAGNOSISMRI shows diffuse enlargement and enhancement of affected nerve

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TREATMENTObservation may be indicated for stable lesions with a good VA

Chemotherapy for progression Radiotherapy is inconclusive

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PROGNOSISBlindness usually 2-4 months after start of vision loss

Death usually within 6-12 months

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TOXIC OR NUTRITIONAL OPTIC NEUROPATHYGradual progressive vision lossPainlessBilateral and symmetric Central scotomaDecrease in VA and color visionDisc edema

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COMMON MEDICATIONS IMPLICATEDEthambutolLinezolid IsoniazidChloramphenicolHydroxyquinolinesPenicillamineCisplatinVincristin

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PROGNOSISSlow resolution of nerve edema over months of discontinuation of substance

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INFILTRATIVE OPTIC NEUROPATHY Infiltration of ON with neoplastic or inflammatory cellsProgressive, sever vision lossOften with painUnilateral or bilateral

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USUAL CAUSESLeukemia Lymphoma Sarcoidosis Syphilis TBFungal

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DIAGNOSISNeuro imagingCSF evaluation

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Metastasis of Leukemia to the Optic nerve head

Note ill defined yellowish infiltrates

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PROGNOSISMetastatic:

Poor even with aggressive therapy

Infectious/Inflammatory: damage may be partially reversed