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Optic neuropathy


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Optic neuropathy

  1. 1. Niwar Ameen O. Duhok Eye Hospital Postgraduate course 2018 OPTIC NEUROPATHY
  2. 2.  The optic nerve begins anatomically at the optic disc but physiologically and functionally within the ganglion cell layer that covers the entire retina.  ON comprise of approximately of 1.0-1.2 million ganglion cell axons.  ON is the second cranial nerve is 5 cm in length.  ON has four portions, they are: - (i) intraocular portion - (ii) intraorbital - (iii) intracanalicular - (iv) intracranial  • It is an outgrowth of the brain  • Its fibers possess no neurolemmal cells  • It is surrounded by the meninges, unlike any peripheral nerve  • Both the primary and secondary neurons are in the retina. INTRODUCTION
  4. 4.  Intraocular segment (optic nerve head) is the shortest, The size of the optic disc varies widely, averaging 1.76 mm horizontally and 1.92 mm vertically.. The ophthalmoscopically visible portion is called the optic disc. Main branches of CRA and CRV passing through the cup.  Intraorbital segment is 25–30 mm long and extends from the globe to the optic foramen at the orbital apex. Its diameter is 3–4 mm because of the addition of the myelin sheaths to the nerve fibres. At the orbital apex the nerve is surrounded by the tough fibrous annulus of Zinn, from which originate the four rectus muscles.  Intracanalicular segment traverses the optic canal and measures about 6 mm. Unlike the intraorbital portion, it is fixed to the canal, since the dura mater fuses with the periosteum.  Intracranial segment joins the chiasm and varies in length from 5 to 16 mm (average 10 mm). Long intracranial segments are particularly vulnerable to damage by adjacent lesions such as pituitary adenomas and aneurysms. ANATOMY
  6. 6. Intraocular portion  The arterial supply of the optic nerve head is as follows: the retrolaminar nerve is supplied chiefly by pial vessels and short posterior ciliary vessels, with some help from the CRA and recurrent choroidal arteries.  The lamina is supplied by short posterior ciliary arteries or by branches of the arterial circle of Haller and Zinn (circle of Zinn-Haller).  The prelaminar nerve is supplied by the short posterior ciliary arteries (cilioretinal arteries, if present) and recurrent choroidal arteries.  The nerve fiber layer is supplied by the CRA. Intraorbital portion  Proximally by the pial vascular network and by neighboring branches of the ophthalmic artery.  Distally, it is also supplied by intraneural branches of the CRA.  Anteriorly, it is supplied by short posterior ciliary arteries and occasional peripapillary choroidal arteries. Intracanalicular portion  It is supplied almost exclusively by the ophthalmic artery. Intracranial portion  It is supplied primarily by branches of both the Internal Carotid A. and the ophthalmic artery. BLOOD SUPPLY
  7. 7.  Optic neuropathy is a frequent cause of vision loss encountered by ophthalmologist.  The diagnosis is made on clinical grounds.  The history often points to the possible etiology of the optic neuropathy. OPTIC NEUROPATHY
  8. 8.  Inflammatory. Optic neuritis, including demyelinating, parainfectious, infectious and non-infectious, and neuroretinitis.  Glaucomatous  Ischaemic. Anterior non-arteritic, anterior arteritic, posterior ischaemic and diabetic papillopathy.  Hereditary. Leber hereditary optic neuropathy, other hereditary optic neuropathies.  Nutritional and toxic  Papilloedematous. Secondary to raised intracranial pressure.  Traumatic  Compressive. Including secondary to an orbital lesion.  Infiltrative. Inflammatory conditions (e.g. sarcoidosis), tumours and infective agents. ETIOLOGICAL CLASSIFICATION OF ON
  9. 9. History 1. The MODE OF ONSET of visual loss is an important clue to the etiology of the optic neuropathy. For example: o Rapid onset is characteristic of optic neuritis, ischemic optic neuropathy, inflammatory (non-demyelinating) and traumatic optic neuropathy. o Gradual onset over months is typical of compressive toxic/nutritional optic neuropathy. o History over years is seen in compressive and hereditary optic neuropathies. 2. ASSOCIATED SYMPTOMS o In young patient history of pain associated with eye movement, paresthesia, limb weakness, and ataxia is suggestive of demyelinating optic neuritis. CLINICAL APPROACH
  10. 10. o In elderly patients transient visual loss, diplopia, temporal pain, jaw claudication, fatigue, weight loss and myalgia suggestive of AION. o In children, history of recent flu-like illness or vaccination days or weeks before vision loss points to a para-infectious or post-vaccinial optic neuritis, respectively. o Symptoms such as diplopia and facial pain are suggestive of multiple cranial neuropathies seen in inflammatory or neoplastic lesions of the posterior orbit or parasellar region. o Transient diplopia and headache should raise the suspicion of increased intra-cranial pressure. 3. DRUG HISTORY o Some medications are either directly or indirectly toxic to the optic nerve. These include drugs as ethambutol, amiodarone, alcohol, and immunosuppressive medications such as methotrexate and cyclosporine.
  11. 11. 4. MEDICAL HISTORY o DM, HrT and hypercholesterolemia is common in patients with non- arteritic ischemic optic neuropathy (NAION). o Patients who are being treated for or have history of malignancy may have infiltrative or para-neoplastic optic neuropathy. 5. SOCIAL HABITS o Such as (drinking, smoking) is important in suspected toxic/nutritional optic neuropathy. 6. FAMILY HISTORY o A detailed family history is important in diagnosing hereditary autosomal and mitochondrial optic neuropathies.
  12. 12. Examination A. Establishment is with classical optic nerve dysfunction, which are: 1. VISUAL ACUITY (VA) can be normal or impaired depending on whether the central visual field is affected. In many cases, visual acuity is normal, yet the patient as a large visual field defect that spares the central field. 2. COLOR VISION can be assessed by using the Ishihara color plates or the American Optical Hardy-Ritter-Rand (AOHRR) pseudoisochromatic color plates. Most patients with acquired optic neuropathy will have dyschromatopsia. 3. A RAPD can be detected by performing the swinging light-pupil test. In the presence of bilateral symmetric optic neuropathy, a RAPD may be absent and the briskness of pupillary constriction to light will reflect the degree of optic nerve dysfunction.
  13. 13. 4. DIMINSHED CONTRAST SENSITIVITY 5. DIMINISHED LIGHT BRIGHTNESS SENSITIVITY, often persisting after visual acuity returns to normal, for instance following the acute stage of optic neuritis. 6. VISUAL FIELD, which vary with the underlying pathology. B. The ophthalmologist should always look for evidence of uveitis such as cells in the anterior vitreous or signs of posterior uveitis such as retinal vasculitis, retinitis, and choroiditis. This would indicate that the disc swelling is secondary to a uveitic process. C. Fundus examination may show normal, swollen, pale or anomalous optic disc.
  14. 14.  The optic disc can be examined using a direct ophthalmoscope or at the slit-lamp using a 78D or 90D lens.  Special attention should be paid to the colour of the disc, and whether the whole disc is paler than usual, or only a segment.  The edge of the disc should be examined to see whether it is distinct or indistinct.  Lastly the retinal blood vessels should be examined as they course over the optic nerve head to see if they are distinct and of normal and regular thickness.  It is important to assess whether both optic discs are equally affected, or whether one disc is normal, less affected or is swollen. HOW TO EXAMINE THE OPTIC DISC
  15. 15. Investigations 1. Visual filed testing: It is an integral component of the neuro- ophthalmic examination and is critical in the diagnosis of optic neuropathy. Both manual kinetic or automated static perimetry can be used. 2. Contrast sensitivity: It is usually reduced in patients with optic neuropathy. Testing charts such as the perri-robson charts can be useful in patients with normal snellen visual acuity. The sensitivity and specificity of this tool, however, is yet to be determined. 3. Electrophysiological tests: are VEP and ERG 4. OCT: optic nerve head, the peripapillary nerve fiber layer can be analyzed. This has been useful in the follow up of patients with optic neuritis, traumatic optic neuropathy, and Leber’s hereditary optic neuropathy.
  16. 16.  Optic neuritis (ON) is a demyelinating inflammation of the optic nerve that typically first occurs in young adulthood.  Demyelination is a pathological process in which 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 in plaques.  Demyelinating disease disrupts nervous conduction within the white matter tracts of the brain, brainstem and spinal cord.  Occasionally, optic neuritis can result from an infectious process involving the orbits or paranasal sinuses or occur in the course of a systemic viral infection. OPTIC NEURITIS
  17. 17.  Demyelinating conditions that may involve the visual system include the following:  Isolated optic neuritis with no clinical evidence of generalized demyelination, although in a high proportion of cases this subsequently develops.  Multiple sclerosis (MS), by far the most common demyelinating disease.  Devic disease (neuromyelitis optica), a very rare disease that may occur at any age, characterized by bilateral optic neuritis and the subsequent development of transverse myelitis (demyelination of the spinal cord) within days or weeks.  Schilder disease, a very rare relentlessly progressive generalized disease with an onset prior to the age of 10 years and death within 1–2 years. Bilateral optic neuritis without subsequent improvement may occur.
  18. 18.  According to ophthalmoscopic appearance 1. Retrobulbar neuritis, 2. Papillitis 3. Neuroretinitis  According to aetiology 1. Demyelinating 2. Parainfectious 3. Infectious 4. Non-infectious CLASSIFICATION
  19. 19.  Multiple sclerosis (MS) is an idiopathic demyelinating disease involving central nervous system white matter. Patients with multiple sclerosis (MS) frequently have visual symptoms, and often the ophthalmologist is the first physician consulted.  Familiarity with both the ocular and neurologic consequences of MS is important in guiding the ophthalmologist to the appropriate diagnosis.  The prevalence of MS varies widely; it is more common in whites and in individuals living in latitudes greater than 40 degrees from the equator.  Research is increasingly pointing to a reduced level of vitamin D in the blood as a risk factor for development of MS.  The disease is 2-3 times more likely to affect women than men. MULTIPLE SCLEROSIS
  20. 20.  It is relatively uncommon in children under 10 years of age, and the incidence is highest among young adults (25-40 years).  The onset even after the age of 50 years is not rare.  Although the cause of MS remains unknown, multiple factors appear contributory. Epidemiologic studies suggest that genetic factors play a role.  Although there is a strong association with the HLA-DRB1 antigen, the genetic associations are multifactorial.  MS significantly increased in first-degree relatives of patients with the disease. Identical twins show a tenfold greater concordance of the disease than do fraternal twins.
  21. 21.  Although MS is classically considered a demyelinating disease, axonal damage does occur early and is an integral part of the disease process.  This axonal loss manifests as "black holes" on the T1-weighted MRI sequences.  Myelin destruction is associated with local perivascular mononuclear cell infiltration, myelin removal by macrophages, and astrocytic proliferation with production of glial fibrils.  The term multiple sclerosis stems from the presence of these numerous gliotic (sclerotic) plaque lesions.  Plaques are often situated in the white matter at the ventricular margins, the optic nerves and chiasm, the corpus callosum, the spinal cord, and throughout the brainstem and cerebellar peduncles. PATHOLOGY IN MULTIPLE SCLEROSIS
  22. 22.  Nonocular signs and symptoms attributable to MS may precede, follow, or coincide with the ocular signs.  Initially, many symptoms of MS are so transient or benign that the patient may fail to remember previous episodes.  Typically, significant episodes last for weeks or months.  The physician must ask specifically about transient diplopia, ataxia, vertigo, patchy paresthesias, bladder or bowel dysfunction, and extremity weakness.  Fatigue and depression are common and may precede the onset of focal neurologic deficits.  The cerebellum, brainstem, and spinal cord may be involved singly or simultaneously, thus producing single or multiple symptoms. PRESENTATION OF MS
  23. 23.  Cerebellar dysfunction: ataxia, dysarthria, intention tremor, truncal or head titubation, dysmetria (sometimes described by the patient as poor depth perception)  Motor symptoms: extremity weakness, facial weakness, hemiparesis, or paraplegia  Sensory symptoms: paresthesias of face or body (especially in a bandlike distribution around the trunk), Lhermitte sign (an electric shock-like sensation in the limbs and trunk produced by neck flexion), pain (occasionally, trigeminal neuralgia)  Mental changes: emotional instability, depression, irritability, fatigue; later in the course, cognitive dysfunction  Sphincter disturbances: frequency, urgency, hesitancy, incontinence; urinary retention leading to urinary tract infection.  It has been suggested but not proved that environmental and infectious agents may induce attacks of MS.  Multiple sclerosis is typically quiescent during the third trimester of pregnancy but may flare up after delivery, suggesting hormonal influences. SOME OF THE MORE COMMON NONOCULAR SYMPTOMS
  24. 24.  Common. Optic neuritis (usually retrobulbar), internuclear ophthalmoplegia, nystagmus.  Uncommon. Skew deviation, ocular motor nerve palsies, hemianopia.  Rare. Intermediate uveitis and retinal periphlebitis.  Uhthoff symptom, transient deterioration of vision may be brought on by exercise or even small elevations in body temperature.  Phosphenes (bright flashes of light) with movement of the affected eye.  Photisms (light induced by noise, smell, taste, or touch). OPHTHALMIC FEATURES
  25. 25. A. Laboratory evaluation of multiple sclerosis  No test unequivocally establishes the presence of MS, which remains a clinical diagnosis.  The CSF in patients with definite MS is abnormal in more than 90% of cases.  The most common abnormalities are elevation of immunoglobulin G (IgG) level, elevation of the IgG/albumin index, and the presence of oligoclonal IgG bands (in CSF but not in serum).  None of these findings, however, is specific for demyelinating disease. B. Neuroimaging in multiple sclerosis  An MRI scan with fluid-attenuated inversion recovery (FLAIR) sequencing and gadolinium infusion is the neuroimaging study of choice for the diagnosis and management of MS.  The MRI scan is particularly sensitive for the identification of white matter plaques in the CNS, and it is far superior to CT scan for visualizing the posterior fossa and spinal cord. INVESTIGATIONS IN MS
  26. 26.  The overall 15-year risk of developing MS following an acute episode of optic neuritis is about 50%.  With no lesions on MRI the risk is 25%, but over 70% in patients with one or more lesions on MRI; the presence of MRI lesions is therefore a very strong predictive factor.  A substantially lower risk of developing MS when there are no MRI lesions is conferred by the following factors; 1. Male gender. 2. Absence of a viral syndrome preceding the optic neuritis. 3. Optic disc swelling, disc/peripapillary haemorrhages or macular exudates. 4. Vision reduced to no light perception. 5. Absence of periocular pain.  Optic neuritis is the presenting feature of MS in up to 25%.  Optic neuritis occurs at some point in 75% of patients with established MS. ASSOCIATION BETWEEN OPTIC NEURITIS AND MULTIPLE SCLEROSIS
  27. 27. Symptoms  ○ Subacute monocular visual impairment.  ○ Usual age range 25–40 years (mean around 30).  ○ Some patients experience tiny white or Coloured flashes or sparkles (phosphenes).  ○ Discomfort or pain in or around the eye is present in over 90% and typically exacerbated by ocular movement; it may precede or accompany the visual loss and usually lasts a few days.  ○ Frontal headache and tenderness of the globe may also be present. Signs  ○ Visual acuity (VA) is usually 6/18–6/60, but may rarely be worse.  ○ Other signs of optic nerve dysfunction, particularly impaired colour vision and a relative afferent pupillary defect. PRESENTATION OF OPTIC NEURITIS
  28. 28.  The optic disc is normal in the majority of cases (retrobulbar neuritis); the remainder show papillitis.  ○ Temporal disc pallor may be seen in the fellow eye, indicative of previous optic neuritis. Visual field defects  ○ Diffuse depression of sensitivity in the entire central 30° is the most common.  ○ Altitudinal/arcuate defects and focal central/centrocaecal scotomas are also frequent.  ○ Focal defects are frequently accompanied by an element of superimposed generalized depression. Course.  Vision worsens over several days to 3 weeks and then begins to improve. Initial recovery is fairly rapid and then slower over 6–12 months.
  29. 29. Prognosis  ○ More than 90% of patients recover visual acuity to 6/9 or better.  ○ Subtle parameters of visual function, such as colour vision, may remain abnormal.  ○ A mild relative afferent pupillary defect may persist.  ○ Temporal optic disc pallor or more marked optic atrophy may ensue.  ○ About 10% develop chronic optic neuritis with slowly progressive or stepwise visual loss.
  30. 30. Indications for steroid treatment  When visual acuity within the first week of onset is worse than 6/12, treatment may speed up recovery by 2–3 weeks and may delay the onset of clinical MS over the short term  This may be relevant in the patients with poor vision in the fellow eye or those with occupational requirements, but the limited benefit must be balanced against the risks of high-dose steroids.  Therapy does not influence the eventual visual outcome and the great majority of patients do not require treatment. Steroid regimen  Intravenous methylprednisolone sodium succinate 1 g daily for 3 days, followed by oral prednisolone (1 mg/kg daily) for 11 days, subsequently tapered over 3 days.  Oral prednisolone may increase the risk of recurrence of optic neuritis if used without prior intravenous steroid. TREATMENT OF OPTIC NEURITIS
  31. 31. Immunomodulatory treatment  (IMT) reduces the risk of progression to clinical MS in some patients, but the risk versus benefit ratio has not yet been fully defined with the options available, which include interferon beta, teriflunomide and glatiramer.  A decision should be individualized, based on risk profile – particularly the presence of brain lesions – and patient preference; most do not commence IMT until a second episode of clinical demyelination has occurred, though there may be an increasing tendency towards a lower threshold.
  32. 32. Para-infectious optic neuritis  Optic neuritis may be associated with viral infections such as measles, mumps, chickenpox, rubella, whooping cough and glandular fever, and may also occur following immunization.  Children are affected much more frequently than adults  Presentation is usually 1–3 weeks after a viral infection, with acute severe visual loss generally involving both eyes.  Bilateral papillitis is the rule.  The prognosis for spontaneous visual recovery is very good, and treatment is not required in the majority of patients.  However, when visual loss is severe and bilateral or involves an only seeing eye, intravenous steroids should be considered, with antiviral cover where appropriate. OTHER CAUSES OF OPTIC NEURITIS
  33. 33. Infectious optic neuritis:  Sinus-related  Cat-scratch fever  Syphilis  Lyme disease (borreliosis)  Cryptococcal meningitis  Varicella zoster virus
  34. 34. Non-infectious optic neuritis Sarcoidosis  Optic neuritis affects 1–5% of patients with neurosarcoid. It may occasionally be the presenting feature of sarcoidosis but usually develops during the course of established systemic disease.  The optic nerve head may exhibit a lumpy appearance suggestive of granulomatous infiltration and there may be associated vitritis. Autoimmune  Autoimmune optic nerve involvement may take the form of retrobulbar neuritis or anterior ischaemic optic neuropathy.
  35. 35. Neuroretinitis  Neuroretinitis refers to the combination of optic neuritis and signs of retinal, usually macular, inflammation.  Cat-scratch fever is responsible for 60% of cases.  About 25% of cases are idiopathic.  Other notable causes include syphilis, Lyme disease, mumps and leptospirosis.  Painless unilateral visual impairment, usually gradually worsening over about a week.  ○ Papillitis associated with peripapillary and macular oedema.  ○ A macular star typically appears as disc swelling settles; the macular star resolves with a return to normal or near-normal visual acuity over 6–12 months.  Treatment: This is specific to the cause, and often consists of antibiotics. Recurrent idiopathic cases may require treatment with steroids and/or other immunosuppressants.
  36. 36.  Non-arteritic anterior ischaemic optic neuropathy (NAION) is caused by occlusion of the short posterior ciliary arteries resulting in partial or total infarction of the optic nerve head.  Predispositions include structural crowding of the optic nerve head so that the physiological cup is either very small or absent.  Hypertension (very common), DM, hyperlipidaemia, collagen vascular disease, antiphospholipid antibody syndrome, hyperhomocysteinaemia, sudden hypotensive events, cataract surgery and sleep apnoea syndrome.  Patients are usually over the age of 50, but are typically younger than those who develop arteritic ION NON-ARTERITIC ANTERIOR ISCHAEMIC OPTIC NEUROPATHY NAION
  37. 37. • Symptoms  ○ Sudden painless monocular visual loss; this is frequently discovered on awakening, suggesting a causative role for nocturnal hypotension. • Signs  ○ VA is normal or only slightly reduced in about 30%. The remainder has moderate to severe impairment.  ○ Visual field defects are typically inferior altitudinal but central, paracentral, quadrantic and arcuate defects may also be seen.  ○ Dyschromatopsia is usually proportional to the level of visual impairment, in contrast to optic neuritis in which colour vision may be severely impaired when VA is reasonably good.  ○ Diffuse or sectoral hyperaemic disc swelling, often associated with a few peripapillary splinter haemorrhages.  ○ Disc swelling gradually resolves and pallor ensues 3–6 weeks after onset. DIAGNOSIS
  38. 38. • Investigation  should include blood pressure, a fasting lipid profile and blood glucose.  It is also very important to exclude occult giant cell arteritis with symptomatic enquiry and testing as appropriate.  Atypical features may prompt special investigations, such as neuroimaging. • Prognosis  Improvement in vision is common although recurrence occurs in about 6%. About 50% of eyes achieve 6/9 or better, though 25% will only reach 6/60 or worse. • Fellow eye  Involvement of the fellow eye occurs in about 10% of patients after 2 years and 15% after 5 years.  When the second eye becomes involved, optic atrophy in one eye and disc oedema in the other gives rise to the ‘pseudo-Foster Kennedy syndrome’.
  39. 39. Treatment  • There is no definitive treatment.  • Optic nerve fenestration has not been shown to be of benefit.  • Some authorities advocate short-term systemic steroid treatment.  • Any underlying systemic predispositions should be treated.  • Although aspirin is effective in reducing systemic vascular events and is frequently prescribed in patients with NAION, it does not appear to reduce the risk of involvement of the fellow eye.
  40. 40.  Arteritic anterior ischaemic optic neuropathy (AAION) is caused by giant cell arteritis (GCA).  About 50% of patients with GCA have polymyalgia rheumatica (PMR) at diagnosis, while around 20% of PMR patients will develop GCA.  PMR is characterized by pain and stiffness in proximal muscle groups, typically the shoulders and biceps, that is worse on waking.  Symptoms can be severe but generally respond dramatically to a low– medium dose (initially 15–20 mg daily) of oral prednisolone.  The causative relationship between GCA and PMR remains uncertain, though many suspect them to be different presentations of the same underlying entity.  Arteritic anterior ischaemic optic neuropathy (AAION) affects 30–50% of untreated patients with GCA, of whom one-third develop involvement of the fellow eye, usually within a week of the first. ARTERITIC ANTERIOR ISCHAEMIC OPTIC NEUROPATHY (AAION)
  41. 41. Symptoms  ○ Sudden, profound unilateral visual loss not uncommonly preceded by transient visual obscurations (amaurosis fugax) and sometimes by double vision.  ○ Periocular pain is common.  ○ Other GCA symptoms are common; most cases of AAION occur within a few weeks of the onset of GCA, although at presentation about 20% do not have systemic symptoms.  ○ Simultaneous bilateral involvement is rare but rapid involvement of the second eye, with resultant total blindness, should always be regarded as a substantial risk. Signs  ○ Severe visual loss is the rule, commonly to only perception of light or worse.  ○ A strikingly pale ‘chalky white’ oedematous disc is particularly suggestive of GCA.  ○ Over 1–2 months, the swelling gradually resolves and severe optic atrophy ensues. DIAGNOSIS
  42. 42. • Prognosis  It is very poor. Visual loss is usually permanent, although, very rarely, prompt administration of systemic steroids may be associated with partial recovery. • Treatment  It is aimed at preventing blindness of the fellow eye, as visual loss in the index eye is unlikely to improve even with immediate treatment; the second eye may still become involved in 25% despite early steroid administration.  The regimen is as follows: Intravenous methylprednisolone, 500 mg to 1 g/day for 3 days followed by oral prednisolone 1–2 mg/kg/day. After 3 more days the oral dose is reduced to 50–60 mg (not less than 0.75 mg/kg) for 4 weeks or until symptom resolution and ESR/CRP normalization. A typical subsequent regimen consists of reducing the daily dose by 10 mg/day every 2 weeks until 20 mg/day is reached, with tapering afterwards titrated against ESR/CRP and symptoms, e.g. a 2.5 mg reduction every 2–4 weeks to 10 mg then a 1 mg reduction every 1–2 months.
  43. 43.  Optic atrophy is not a disease in itself but a clinical sign.  It refers to pallor of the optic disc which results from irreversible damage to the retinal ganglion cells and axons.  The axons of the retinal ganglion cells make up the optic nerve and continue onto the optic chiasm, optic tract and up to the lateral geniculate body before they synapse.  Injury to the retinal ganglion cells and axons anywhere along their course from the retina to the lateral geniculate body may result in optic atrophy.  The causes of optic atrophy are numerous; they include: 1. Inflammation 2. Ischaemia 3. Compression, including raised intracranial pressure 4. Nutritional deficiencies / effect of toxins, including epidemic 5. Trauma 6. Hereditary conditions and childhood optic atrophy OPTIC ATROPHY
  44. 44.  Diminution of vision (central acuity/colour vision/visual field defects)  Afferent pupil defect  Optic disc pallor  Reduced number of small blood vessels on the disc surface (Kestenbaum sign)  Attenuation (thinning) of blood vessels around the disc  Thinning of the retinal nerve fiber layer. CLINICAL FEATURES IN OPTIC ATROPHY
  45. 45.  Non pathologic causes of a pale disc: 1. Disc is examined with very bright light 2. Large physiologic cup in axial myopia 3. Post-cataract extraction  Other (non optic atrophy) causes of a pale disc: 1. Myelinated retinal nerve fibers 2. Optic disc coloboma 3. Optic disc hypoplasia CAUSES OF PSEUDO OPTIC ATROPHY
  46. 46. Primary optic atrophy Secondary optic atrophy Consecutive optic atrophy Glaucomatous optic atrophy OPHTHALMOSCOPIC CLASSIFICATION OA
  47. 47.  Primary optic atrophy occurs without antecedent swelling of the optic nerve head.  It may be caused by lesions affecting the visual pathways at any point from the retrolaminar portion of the optic nerve to the lateral geniculate body.  Lesions anterior to the optic chiasm result in unilateral optic atrophy, whereas those involving the chiasm and optic tract will cause bilateral changes. Important causes  Optic neuritis  Compression by tumours and aneurysms  Hereditary optic neuropathies  Toxic and nutritional optic neuropathies; these may give temporal pallor, particularly in early/milder cases when the papillomacular fibres are preferentially affected.  Trauma PRIMARY OPTIC ATROPHY
  48. 48. Signs  Flat white disc with clearly delineated margins.  Reduction in the number of small blood vessels on the disc surface.  Attenuation of peripapillary blood vessels and thinning of the retinal nerve fibre layer (RNFL).  The atrophy may be diffuse or sectoral depending on the cause and level of the lesion.  Temporal pallor of the optic nerve head may indicate atrophy of fibres of the papillomacular bundle, and is classically seen following demyelinating optic neuritis.  Band atrophy is a similar phenomenon caused by involvement of the fibres entering the optic disc nasally and temporally; it occurs in lesions of the optic chiasm or tract and gives nasal as well as temporal pallor.
  49. 49.  Secondary optic atrophy is preceded by long-standing swelling of the optic nerve head. Signs vary according to the cause and its course.  Slightly or moderately raised white or greyish disc with poorly delineated margins due to gliosis.  Obscuration of the lamina cribrosa.  Reduction in the number of small blood vessels on the disc surface.  Peripapillary circumferential retinochoroidal folds, especially temporal to the disc (Paton lines), sheathing of arterioles and venous tortuosity may be present. Causes  Include chronic papilloedema, anterior ischaemic optic neuropathy and papillitis.  Intraocular inflammatory causes of marked disc swelling are sometimes considered to cause secondary rather than consecutive atrophy. SECONDARY OPTIC ATROPHY
  52. 52.  Consecutive optic atrophy is caused by disease of the inner retina or its blood supply.  The cause is usually obvious on fundus examination, e.g. extensive retinal photocoagulation, retinitis pigmentosa or prior central retinal artery occlusion.  The disc appears waxy, with reasonably preserved architecture. CONSECUTIVE OPTIC ATROPHY
  54. 54. Manual of Neuro-Ophthalmology, Amar Agarwal and Athiya Agarwal, 1st E 2009. AAO, Neuro-Ophthalmology BCSC 2016- 2017 AAO, Fundamental and principles of ophthalmology, BCSC 2016-2017 Kanski’s clinical ophthalmology, 8th edition, 2016   REFERENCES