Seminar On Optic Atrophy

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. qFinal endpoint of any disease process causing axon degeneration qClinically, manifests as changes in the color & structure of optic disc qVariable degrees of visual dysfunction. qActually a misnomer qActually,atrophy refers to involution of a

OPTIC NERVE qIInd cranial nerve (neurosensory) qComprises approximately 1.2 million axons qOriginate at the ganglion cell layer of the retina. qThe axons are myelinated by oligodendrocytes, qThe axons do not regenerate. qBehaves more like a white matter tract  

Visual pathway qUnilateral atrophy Lesion involving anterior to optic chiasm qBilateral atrophy Lesion involving

The optic nerve is divided into the following 4 parts: 4. Intraocular part =optic nerve head (1 mm) 5. Intraorbital part (25 mm) 6. Intracanalicular part (5 mm) 7. Intracranial part (10 mm)

Blood supply of optic nerve

INTRAORBITAL b) Periaxial :ophthalmic A,Long posterior ciliary A,Short posterior ciliary A,Lacrimal A,Central a of retina c) 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

INTRAOCULAR 1.Surface N. fibre layer Capillaries from retinal arterioles 2.Prelamiar region Short posterior ciliary A, Choroidal A 3.Laminar cribrosa Short posterior ciliary A Circle of Zinn-Haller 4.Retrolaminar region

FEATURES OF NORMAL OPTIC NERVE

Normal nerve fibre layer

Optic nerve atrophy

Hi st opa thol og ic c ha nge s in opt ic a tr oph y v Shrinkage or loss of both myelin and axis cylinders v Widening of the pial septa v Gliosis v Deepening of the physiologic cup with barring of the lamina cribrosa v Widening of the subarachnoid space with redundant dura v Severed nerve leads to bulbous axonal swellings (Cajal end bulbs)

Path ologic cl assif ica tion v  Anterograde degeneration (Wallerian degeneration) q Deterioration begins in the retina and proceeds toward the lateral geniculate body (ie, to the brain). q Toxic retinopathy, chronic simple glaucoma

v Retrograde degeneration q Deterioration starts from the proximal portion of the axon and proceeds toward the optic disc (ie, to the eye). q Intracranial tumor

v Trans-synaptic degeneration

Oph th almo sco pic cl assif ica tion

PRIMARY OPTIC ATROPHY

Secondary optic atrophy

CONSECUTIVE OPTIC ATROPHY

GLAUCOMATOUS/CAVERNOUS OPTIC ATROPHY

Eti ol ogi c c las si fic ati on 1) Hereditary 1) Congenital or infantile optic atrophy  2) Behr hereditary optic atrophy 3) Leber optic atrophy

2) Consecutive atrophy 3) Circulatory atrophy 4) Metabolic atrophy :

Thyroid ophthalmopathy, juvenile diabetes mellitus, nutritional amblyopia, toxic amblyopia, tobacco, methyl alcohol, and drugs (eg, ethambutol, sulphonamides). 5) Demyelinatingatrophy : 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.

ATROPHY

DIFFUS E SECTORAL

Monocular band optic atrophy qBand or "bow tie" optic atrophy qHomonymous hemianopia qInvovement of fibre entering optic disc nasally & temporally(sparing superior & inferior portion) qUnilateral visual defect.

qAssociated with compressive lesions of the pregeniculate post-chiasmal pathway (or) qCongenital malformations of postgeniculate radiations or cortex. qThe optic atrophy is strictly U/L CAUSES qAfter retrobulbar neuritis qTumour & aneurysms qHereditary optic neuropathies qToxic & nutritional optic

Primary optic atrophy qDisc is chalky white qWell defined margins qLamina cribrosa is well defined qSlight cupping shallow,saucer shaped qSurrounding retina is normal qKestenbaum sign

ETIOLOGY OF POA qIdiopathic qDemyelination qPost inflammatory qToxic qInflammation of orbit, sinus and meninges qCompressive qNutritional qHereditary

www.riogohchennai.ac.inSeptember 2006

POST INFLAMMATORY TABES & GENERAL PARALYSIS qInflammation affects pial sheath resulting in degenerative change qGradual loss of vision qContraction of fields for colours TREATMENT:Penicillin eradicate infection &arrest optic atrophy 19

Acute retrobulbar neuritis It frequently affects only temporal ½ of disc It occurs in qDisseminated sclerosis qLoss of blood qFocal sepsis & catarrhal disease of nasal sinus qOrbital inflammation qInfectiousDiseases:Meningitis/Encephalomy elitis, qVaccination qNutritional disorder

CHRONIC RETROBULBAR NEURITIS CAUSES qTobacco(most common) qMethyl alcohol,ethyl alcohol qLead qQuinine qCarbon di sulphide,iodoform,thallium qArsenical preparations

MENINGITIS INCLUDING ARACHNOIDITIS OPTICO CHIASMATICA q Type of atrophy:descending Arachnoiditis optico chiasmatica q Chronic progressive disease q affected by direct pressure from membrane,cords or cysts SIGN Optic arachnoiditis on basal q U/L or B/L loss of vision surface of pons & inter q Centre or paracentral scotoma peduncular fossa q Peripheral fields contraction q Primary /secondary optic atrophy

treatment Treatment is mainly surgical qFreeing of adhesions qLibration of cystic fluid

COMPRESSIVE OPTIC NEUROPATHY qProgressive scotoma qInitially normal disc qSigns of atrophy qDecrease in color qDecrease in vessels

TRAUMA (COMPRESSIVE) ETIOLOGY qDistension of optic sheaths with blood under pressure qBy bony fragments due to fracture of optic foramen

TUMOUR AND BONE DISEASES qTumour in optic nerve,orbit and base of skull qCauses pressure atrophy. qGrowth position indicated by clinical findings & visual fields. Optocilliary blood vessels

CAUSES qPituitary tumour qSuprasellar meningioma qOsteopetrosis(albers schoenberg’s disease) qIdiopathic hypercalcemia

SECONDARY OPTIC ATROPHY qDisc is grey or dirty grey qMargins are poorly defined qLamina cribrosa obscured qPeripapillary sheathing of Artery qTortorous veins qKestenbaum’s sign

Secondary optic atrophy q Ischaemic optic neuropathy q Chronic papilloedema q Chronic optic neuritis

Causes of secondary optic atrophy q Infectious Disorders (Specific q Metabolic, Storage Disorders Agent) q Tay-Sachs disease q Syphilis q Gangliosidosis q General paresis/CNS syphilis dementia, generalized (GM1) q Infantile ceroid lipofuscinosis /Finnish (Santvuori-Haltia) q Meningitis, cryptococcal q Juvenile ceroid lipofuscinosis q Tabes dorsalis /Batten-M q Granulomatous, Inflammatory q Sandhoff disease Disorders q Orbital inflammatory disease

q Neoplastic Disorders q Kennedy syndrome q Sellar tumor/suprasellar extension q Meningioma q Suprasella tumor

q Allergic, Collagen, AutoImmune Disorders q Takayasu's pulseless aortitis synd.

q Deficiency Disorders

q Anemia of malnutrition q Malnutrition/Starvation

q Congenital, Developmental Disorders

q Craniofacial dysostosis/ Crouzon q Optic atrophy-ataxia syndrome

q Familial, Genetic Disorders

q Vegetative, Autonomic, Endocrine Disorders

q Acrodermatitis q Pseudotumor cerebri enteropathica /Benign Intracranial Hyperten q Cockayne syndrome q Leukodystrophy, Krabbe q Reference to Organ q Optic atrophy, hereditary, ofSystem Leber q Optic atrophy, secondary q Pelizaeus-Merzbacher q Optic neuritis, acute disease q Pernicious anemia q Brooks syndrome

q Usage, Degenerative, Necrosis, Age Related Disorders q Multiple sclerosis q Optic atrophy, primary

q Arteriosclerotic, Vascular, Venous Disorders

q Drugs

q Tryparsamide Administration/Toxicity q Suramin (Germanine/ Antrypol ) Administration/Toxicity q Khat herbal/intake

q Poisoning (Specific Agent)

q Methanol ingestion/poisoning

GLAUCOMATOUS OPTIC ATROPHY qMarked excavation of optic disc qPosterior bowing of lamina cribrosa qColumnar atrophy qDecrease in number & size of small blood vessels

qIncreased IOP recession of lamina cribrosa qCupping depends on qIOP qToughness of lamina cribrosa.

qAtrophy of the nerve fibers occurs due to q IOP q vascular sclerosis

qThe degeneration is of nerve fibers and ganglion cells & inner plexiform & inner nuclear layers. qGlucomatous excavation is due to qatrophy of the nerve qdisappearance of glial tissue

qThe duration of increased IOP

SCHNABEL’S CAVERNOUS OPTIC ATROPHY qSchnabel ‘s theory :cupping of the disc in glaucoma was not due to IOP Enlarge to fron qSeen in glaucoma formwithout raised t large IOP Minute cavities cavity in front & behind lamina

behind

Collapse & form cup

qProgressive diminution of blood supply of the nerve disappearance of nerve fibers.

CONSECUTIVE OPTIC ATROPHY qAssociated with lesions of retina & choroid. qIn chorioretinitis & primary pigmentary degeneration of the retina. qInflammatory / degenerative lesions. qAscending type OPHTHALMOSCOPICALLY qYellowish waxy disc qAttenuated retinal vessels Optic atrophy in Retinitis qChanges in the surrounding pigmentosa

HEREDITARY

INFANTILE HEREDITARY ATROPHY

BEHR’S DISEASE

LEBER’S DISEASE

INFANTILE HEREDITARY OPTIC ATROPHY qRecessive inheritence qLoss of vision qConstricted visual field qNystagmus

CONGENITAL OPTIC ATROPHY

MOTHER

SON

Behr’s optic atrophy qBegins in infancy qAutosomal recessive qIncomplete bilateral optic atrophy with temporal pallor of both disc qAssociated with neurological abnormalities:cerebellar ataxia,spasticity, Pyramidal tract abnomality

Leber’s optic atrophy qBilateral qRecessive X-linkage mitochondrial DNA mutation 11778 qIn adolescent males qUnilateral visual defect. qCentral field defect:pericentral (or) paracentral scotoma qBlindness unusual qColour blindness except blue & violet

Telangiectic microangiopathy

Severe optic

Dif fere nti al D iag nosis qAxial myopia qOptic nerve hypoplasia qBrighter-than-normal luminosity Optic nerve pit qOptic nerve pit qMyelinated nerve fibers qScleral crescent qOptic disc drusen qTilted disc Temporal crescent

Symptoms qBlurred vision qAbnomal side vision qDefective color vision qDecreased brightness in one eye relative to the other

WORK-UP OF OPTIC ATROPHY q Visual acuity q Colour vision q Contrast sensitivity test q Pupillary evaluation q Pupil size q RAPD(Relative afferent pupillary defect)

q q q q q q q q q

Edge-light pupil cycle time Photostess recovery test Pulfrich phenomenon Cranial nerve examination Extraocular movements Visual field PULFRICH PHENOMENON EEG Visually evoked response Imaging technique q B-scan, q CT scan,MRI q Gadolinium enhanced MRI MRI in multiple sclerosis

BILATERAL OPTIC ATROPHY WITH CENTROCECAL SCOTOMAS qHereditary (dominant, Leber’s) qToxic (medications, methanol, heavy metals) qNutritional (folate, B12) qDemyelinating (optic neuritis, multiple sclerosis)

CENTROCECAL

OTHER INVESTIGATIONS q MRI of the brain and orbits with contrast q CT scanning of the brain and orbits with contrast :spaceoccupying lesion [SOL], sinusitis, hyperpneumatized sinuses, fibrous dysplasia)  q Blood glucose level q Blood pressure, cardiovascular examination q Carotid Doppler ultrasound study q Vitamin B-12 levels q Venereal Disease Research Laboratory (VDRL)/Treponema pallidum hemagglutination (TPHA) tests q Antinuclear antibody levels q Sarcoid examination q Homocysteine levels q Antiphospholipid antibodies q Enzyme-linked immunosorbent assay (ELISA) for toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus (TORCH panel)

Treatme nt Medical Care q No proven treatment exists for optic atrophy. q Treatment initiated before the development of optic atrophy can be helpful q The role of intravenous steroids is proven in a case of qoptic neuritis qarteritic anterior ischemic optic neuropathy.

q Idebenone, a quinone analog is on trial Leber hereditary optic neuropathy to ameliorate the net ATP synthesis q Stem cell treatment :future treatment of neuronal disorders. q At present, the best defense is an early

PREVENTION qEarly detection of inflammations qSome doctors recommend vitamin C, vitamin E, coenzyme Q10, or other antioxidants, qAvoid tobacco / alcohol qAvoiding toxin exposure qAvoid nutritional deficiency qEarly diagnosis and prompt treatment of compressive & toxic neuropathies qGenetic counselling in hereditary disease

Vitamin, Water Soluble Essential to normal metabolism and DNA synthesis. Cyanocobalamin (Nascobal) qDeoxyadenosylcobalamin and hydroxocobalamin are active forms of vitamin B-12. qVitamin B-12 synthesized by microbes qRequired for healthy neuronal functions and normal functions of rapidly growing cells.

Dosin g Adult q Vitamin B-12 deficiency: 1000 mcg PO once a day Pernicious anemia or other causes that decrease oral absorption, administer parenteralinjection of 30 mcg IM/Sc once a day for 5-10 d, then 100-200 mcg IM/SC once a month

q Intranasal gel: 500 mcg in one nostril once a wk

Pediatric q Oral administration: <12 years: Not established >12 years: Administer as in adults q 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

q Intranasal gel: Not established

Fur th er O utpatie nt C are qLow-vision aids for occupational rehabilitation.

PROGNOSIS qEarly and intensive treatment of cause provide patients with near-normal vision

U O Y K N A H T