OPTIC ATROPHY
INTRODUCTION DEFINITION:Optic atrophy can be defined as
damage to the optic nerve resulting in a degeneration or destruction of the optic nerve.
Final endpoint of any disease process causing
axon degeneration Clinically, manifests as changes in the color &
structure of optic disc Variable degrees of visual dysfunction. Actually a misnomer Actually,atrophy refers to involution of a
structure resulting from prolonged disuse.
OPTIC NERVE
IInd cranial nerve (neurosensory)
Comprises approximately 1.2 million axons
Originate at the ganglion cell layer of the retina.
The axons are myelinated by oligodendrocytes,
The axons do not regenerate.
Behaves more like a white matter tract
VISUAL PATHWAY Unilateral
atrophy Lesion involving
anterior to optic chiasm
Bilateral atrophy Lesion involving
chiasm &optic tract
The optic nerve is divided into the
following 4 parts:
1. Intraocular part =optic nerve head (1 mm)
2. Intraorbital part (25 mm)
3. Intracanalicular part (5 mm)
4. Intracranial part (10 mm)
BLOOD SUPPLY OF OPTIC NERVE
INTRAORBITAL a) Periaxial :ophthalmic
A,Long posterior ciliary A,Short posterior ciliary A,Lacrimal A,Central a of retina
b) Axial : Intraneural br of Central retinal A,Collateral br,Central A of optic N
INTRACANALICULAR Periaxial system INTRACRANIAL: Periaxial Br of int carotid A;Br from
ant cerebral A;small recurrent br from ophthalmic A;Ant communicating A.
INTRAOCULAR1.Surface N. fibre
layer Capillaries from
retinal arterioles2.Prelamiar region Short posterior
ciliary A, Choroidal A3.Laminar cribrosa Short posterior
ciliary A Circle of Zinn-Haller4.Retrolaminar region Pial blood vessels
FEATURES OF NORMAL OPTIC NERVE
NORMAL NERVE FIBRE LAYER OPTIC NERVE ATROPHY
HISTOPATHOLOGIC CHANGES IN OPTIC ATROPHY
Shrinkage or loss of both myelin and axis cylinders Widening of the pial septa Gliosis Deepening of the physiologic cup with barring of
the lamina cribrosa Widening of the subarachnoid space with
redundant dura Severed nerve leads to bulbous axonal swellings
(Cajal end bulbs)
PATHOLOGIC CLASSIFICATION
Anterograde degeneration (Wallerian degeneration) Deterioration begins in the retina and proceeds toward
the lateral geniculate body (ie, to the brain). Toxic retinopathy, chronic simple glaucoma
Retrograde degeneration Deterioration starts from the proximal portion of the
axon and proceeds toward the optic disc (ie, to the eye). Intracranial tumor
Trans-synaptic degeneration A neuron on one side of a synapse degenerates as a
consequence of the loss of a neuron on the other side. Occipital damage incurred in utero or during early
infancy.
OPHTHALMOSCOPIC CLASSIFICATION
PRIMARY OPTIC ATROPHY SECONDARY OPTIC ATROPHY
GLAUCOMATOUS/CAVERNOUS OPTIC ATROPHYCONSECUTIVE OPTIC ATROPHY
ETIOLOGIC CLASSIFICATION
1) Hereditary 1) Congenital or infantile optic atrophy 2) Behr hereditary optic atrophy3) Leber optic atrophy
2) Consecutive atrophy3) Circulatory atrophy4) Metabolic atrophy :
Thyroid ophthalmopathy, juvenile diabetes mellitus, nutritional amblyopia, toxic amblyopia, tobacco, methyl alcohol, and drugs (eg, ethambutol, sulphonamides).
5) Demyelinating atrophy : multiple sclerosis and Devic disease.
6) Pressure or traction atrophy : glaucoma and papilledema. 7) Postinflammatory atrophy : optic neuritis, perineuritis secondary
to inflammation of the meninges, sinus and orbital cellulites. 8) Traumatic optic neuropathy: Optic nerve avulsion and transection,
optic nerve sheath hematoma, and optic nerve impingement from a penetrating foreign body or bony fragment
ATROPHY
Monocular band optic atrophy Band or "bow tie" optic atrophy Homonymous hemianopia Invovement of fibre entering optic disc
nasally & temporally(sparing superior & inferior portion)
Unilateral visual defect.
DIFFUSE
SECTORAL
Associated with compressive lesions of the pregeniculate post-chiasmal pathway (or)
Congenital malformations of postgeniculate radiations or cortex.
The optic atrophy is strictly U/L
CAUSES After retrobulbar neuritis Tumour & aneurysms Hereditary optic neuropathies Toxic & nutritional optic
neuropathies
PRIMARY OPTIC ATROPHY
Disc is chalky white
Well defined margins
Lamina cribrosa is well defined
Slight cupping shallow,saucer shaped
Surrounding retina is normal
Kestenbaum sign
ETIOLOGY OF POA
Idiopathic Demyelination Post inflammatory Toxic Inflammation of orbit, sinus and meninges Compressive Nutritional Hereditary
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POST INFLAMMATORY
TABES & GENERAL PARALYSIS Inflammation affects pial sheath
resulting in degenerative change Gradual loss of vision Contraction of fields for colours
TREATMENT:Penicillin eradicate infection &arrest optic atrophy
September 2006
19 / 12
ACUTE RETROBULBAR NEURITISIt frequently affects only temporal ½ of discIt occurs in Disseminated sclerosis Loss of blood Focal sepsis & catarrhal disease of nasal sinus Orbital inflammation
InfectiousDiseases:Meningitis/Encephalomyelitis,
Vaccination Nutritional disorder
CHRONIC RETROBULBAR NEURITIS
CAUSES Tobacco(most common) Methyl alcohol,ethyl alcohol Lead Quinine Carbon di sulphide,iodoform,thallium Arsenical preparations
MENINGITIS INCLUDING ARACHNOIDITIS OPTICO CHIASMATICA
Type of atrophy:descending
Arachnoiditis optico chiasmatica Chronic progressive disease affected by direct pressure from membrane,cords or cysts
SIGN U/L or B/L loss of vision Centre or paracentral scotoma Peripheral fields contraction Primary /secondary optic atrophy
Optic arachnoiditis on basal surface of pons & inter peduncular fossa
TREATMENT
Treatment is mainly surgical Freeing of adhesions Libration of cystic fluid
COMPRESSIVE OPTIC NEUROPATHY
Progressive scotoma
Initially normal disc
Signs of atrophy Decrease in color Decrease in
vessels Decrease in NFL
TRAUMA (COMPRESSIVE)
ETIOLOGY Distension of optic sheaths with blood
under pressure By bony fragments due to fracture of
optic foramen
TUMOUR AND BONE DISEASES Tumour in optic nerve,orbit and base of skull Causes pressure atrophy. Growth position indicated by clinical findings
& visual fields.
CAUSES Pituitary tumour Suprasellar meningioma Osteopetrosis(albers schoenberg’s disease) Idiopathic hypercalcemia
Optocilliary blood vessels
SECONDARY OPTIC ATROPHY Disc is grey or dirty
grey Margins are poorly
defined Lamina cribrosa
obscured Peripapillary
sheathing of Artery Tortorous veins Kestenbaum’s sign
SECONDARY OPTIC ATROPHY Ischaemic optic neuropathy Chronic papilloedema Chronic optic neuritis
CAUSES OF SECONDARY OPTIC ATROPHY Infectious Disorders (Specific
Agent) Syphilis General paresis/CNS syphilis deme
ntia
Meningitis, cryptococcal Tabes dorsalis
Granulomatous, Inflammatory Disorders Orbital inflammatory disease
Neoplastic Disorders Kennedy syndrome Sellar tumor/suprasellar extension Meningioma Suprasella tumor
Allergic, Collagen, Auto-Immune Disorders Takayasu's pulseless aortitis synd. Behcet's syndrome
Metabolic, Storage Disorders Tay-Sachs disease Gangliosidosis
, generalized (GM1) Infantile ceroid lipofuscinosis
/Finnish (Santvuori-Haltia) Juvenile ceroid lipofuscinosis
/Batten-M Sandhoff disease
Deficiency Disorders Anemia of malnutrition Malnutrition/Starvation
Congenital, Developmental Disorders Craniofacial dysostosis/
Crouzon Optic atrophy-ataxia syndrom
e
Familial, Genetic Disorders Acrodermatitis
enteropathica Cockayne syndrome Leukodystrophy, Krabbe Optic atrophy, hereditary,
of Leber
Pelizaeus-Merzbacher disease
Brooks syndrome Usage, Degenerative,
Necrosis, Age Related Disorders Multiple sclerosis Optic atrophy, primary
Arteriosclerotic, Vascular, Venous Disorders Optic neuritis, ischemic
Vegetative, Autonomic, Endocrine Disorders Pseudotumor cerebri
/Benign Intracranial Hypertension
Reference to Organ System Optic atrophy, secondary Optic neuritis, acute Pernicious anemia
Drugs Tryparsamide
Administration/Toxicity Suramin (Germanine/
Antrypol) Administration/Toxicity
Khat herbal/intake Poisoning (Specific Agent)
Methanol ingestion/poisoning Lead encephalopathy
GLAUCOMATOUS OPTIC ATROPHY
Marked excavation of optic disc
Posterior bowing of lamina cribrosa
Columnar atrophy Decrease in number &
size of small blood vessels
Increased IOP recession of lamina cribrosa
Cupping depends on IOP Toughness of lamina cribrosa.
Atrophy of the nerve fibers occurs due to IOP vascular sclerosis
The degeneration is of nerve fibers and ganglion cells & inner plexiform &
inner nuclear layers. Glucomatous excavation is due to
atrophy of the nerve disappearance of glial tissue
The duration of increased IOP is the chief factor in causing cupping.
SCHNABEL’S CAVERNOUS OPTIC ATROPHY
Schnabel ‘s theory :cupping of the disc in glaucoma was not due to IOP
Seen in glaucoma without raised IOP
Progressive diminution of blood supply of the nerve disappearance of nerve fibers.
Histologically Mucoid degeneration of the glia
Disappearance of the optic nerve fibers.
Minute cavities in front & behind lamina
Enlarge to form large cavity
Collapse & form cup
front
behind
CONSECUTIVE OPTIC ATROPHY Associated with lesions of retina &
choroid. In chorioretinitis & primary pigmentary
degeneration of the retina. Inflammatory / degenerative lesions. Ascending type
OPHTHALMOSCOPICALLY Yellowish waxy disc Attenuated retinal vessels Changes in the surrounding retina
Optic atrophy in Retinitis pigmentosa
HEREDITARY
INFANTILE HEREDITARY OPTIC ATROPHY Recessive inheritence Loss of vision Constricted visual field Nystagmus
INFANTILE HEREDITARY ATROPHY
BEHR’S DISEASE
LEBER’S DISEASE
CONGENITAL OPTIC ATROPHY
MOTHER SON
BEHR’S OPTIC ATROPHY
Begins in infancy Autosomal recessive Incomplete bilateral optic atrophy with
temporal pallor of both disc Associated with neurological
abnormalities:cerebellar ataxia,spasticity, Pyramidal tract abnomality
LEBER’S OPTIC ATROPHY Bilateral Recessive X-linkage mitochondrial DNA mutation 11778 In adolescent males Unilateral visual defect. Central field defect:pericentral
(or) paracentral scotoma Blindness unusual Colour blindness except blue
& violet Telangiectic microangiopathy
Telangiectic microangiopathy
Severe optic atrophy
DIFFERENTIAL DIAGNOSIS
Axial myopia Optic nerve hypoplasia Brighter-than-normal luminosity Optic nerve pit Myelinated nerve fibers Scleral crescent Optic disc drusen Tilted disc
Optic nerve pit
Temporal crescent
SYMPTOMS
Blurred vision Abnomal side vision Defective color vision Decreased brightness in one eye
relative to the other
WORK-UP OF OPTIC ATROPHY
Visual acuity Colour vision Contrast sensitivity test Pupillary evaluation
Pupil size RAPD(Relative afferent
pupillary defect)
Edge-light pupil cycle time Photostess recovery test Pulfrich phenomenon Cranial nerve examination Extraocular movements Visual field EEG Visually evoked response Imaging technique
B-scan, CT scan,MRI Gadolinium enhanced MRI
PULFRICH PHENOMENON
MRI in multiple sclerosis
BILATERAL OPTIC ATROPHY WITH CENTROCECAL SCOTOMAS
Hereditary (dominant, Leber’s)
Toxic (medications, methanol, heavy
metals) Nutritional (folate,
B12) Demyelinating (optic
neuritis, multiple sclerosis)
CENTROCECAL SCOTOMAS
OTHER INVESTIGATIONS MRI of the brain and orbits with contrast CT scanning of the brain and orbits with contrast :space-
occupying lesion [SOL], sinusitis, hyperpneumatized sinuses, fibrous dysplasia)
Blood glucose level Blood pressure, cardiovascular examination Carotid Doppler ultrasound study Vitamin B-12 levels Venereal Disease Research Laboratory (VDRL)/Treponema
pallidum hemagglutination (TPHA) tests Antinuclear antibody levels Sarcoid examination Homocysteine levels Antiphospholipid antibodies Enzyme-linked immunosorbent assay (ELISA) for
toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus (TORCH panel)
TREATMENT
Medical Care No proven treatment exists for optic atrophy. Treatment initiated before the development of optic
atrophy can be helpful The role of intravenous steroids is proven in a case
of optic neuritis arteritic anterior ischemic optic neuropathy.
Idebenone, a quinone analog is on trial Leber hereditary optic neuropathy to ameliorate the net ATP synthesis
Stem cell treatment :future treatment of neuronal disorders.
At present, the best defense is an early diagnosis
PREVENTION
Early detection of inflammations Some doctors recommend vitamin C, vitamin
E, coenzyme Q10, or other antioxidants, Avoid tobacco / alcohol Avoiding toxin exposure Avoid nutritional deficiency Early diagnosis and prompt treatment of
compressive & toxic neuropathies Genetic counselling in hereditary disease
Vitamin, Water Soluble Essential to normal metabolism and
DNA synthesis.
Cyanocobalamin (Nascobal) Deoxyadenosylcobalamin and
hydroxocobalamin are active forms of vitamin B-12.
Vitamin B-12 synthesized by microbes Required for healthy neuronal functions
and normal functions of rapidly growing cells.
DOSING
Adult Vitamin B-12 deficiency: 1000 mcg PO once a day
Pernicious anemia or other causes that decrease oral absorption, administer
parenteral injection of 30 mcg IM/Sc once a day for 5-10 d, then 100-200 mcg IM/SC once a month
Intranasal gel: 500 mcg in one nostril once a wk
Pediatric Oral administration:
<12 years: Not established>12 years: Administer as in adults
Alternatively, 100 mcg IM/SC once a day for 10-15 d (total dose of 1-1.5 mg), then 60-100 mcg IM/SC once or twice weekly for several month
Intranasal gel: Not established
FURTHER OUTPATIENT CARE
Low-vision aids for occupational rehabilitation.
PROGNOSIS Early and intensive treatment of cause
provide patients with near-normal vision
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