Post on 24-Jan-2017
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Symptoms & Signs in Clinical Medicine
By/Mohamed Ahmed El –Shafie
Assistant Lecturer in ophthalmology department KafrELShiekh University
Anatomy of optic nerve• Optic nerve- more than 1 million axons.• Consisting of axons originating from ganglion
cells.
• Starts from optic disc upto optic chiasma.• Contains the afferent fibers of light reflex.
• Elongated tract of white matter • Not covered by neurilemma.
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• Optic nerve divided in topographic areas:
Intraocular portion.Intraorbital portion.Intracanalicular portion.Intracranial portion.
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Intraocular optic nerve
• 1 mm in length.• 1.5 mm diameter.• Which expands approximately 3-4 mm behind
the sclera.
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Intraorbital optic nerve
Relation of ophthalmic arteryAt the optic foramen: inferior and lateral
Lateral to optic nerve (in posterior orbit)
Inferior division of 3rd nerve-Sixth NerveCiliary ganglionNasociliary artery
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At the orbital apex – optic nerve surrounded by annulus of Zinn.
Blood supply: Ophthalmic artery with meningeal branches
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Intracanalicular optic nerve
• 9 mm
• Tightly fixed within the canal (compressive optic neuropathy Optic nerve edema)
• Blunt trauma
Blood supply: Pial branches from ophthalmic artery.
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Intracranial optic nerve
• Length-10mm• Diameter-4.5mm
Extends post & medially ascending at an angle of 45º to join the chiasma
Blood supply: pial vessels arising from ICA branches from ant cerebral and anterior communicating artery
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Normal optic disc
- Color: Orange or pink
- Margin- Counter- Crescent- Distribution of veins.
Why the normal disc is pink?
• Thickness and the cytoarchitecture of fiber bundles passing between glial columns containing capillaries
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• Pathologies of the optic nerve, even though not always detected on ophthalmoscopic exam, may compromise its function and cause the following sign;
Visual Acuity Near vision
- Reading from a book
Far vision
- Snellen chart.
- Ishihara charts
Dyschromatopsia • Impaired color vision = 94%• Desaturation
• – eg: red = dark/ beached
• Distinguishes b/w macular lesion
confrontation
Kinetic perimetry Static perimetry Kinetic perimetry Static perimetry
• all patients show V.F abnormalities in acute phase
Central ⁺⁺⁺, peripheral⁺, particular region⁺ • If Vn severely impaired – confrontation test
• Vision improved – • kinetic Goldman Perimetry ( only central scotoma)• Automated static Perimetry
• Focal defect – • Altitudinal • Arcaute • Nasal step defect
• Stimulus• Receptors• Afferent• Center• Efferent• Effector organ• Effect
Pup. light reflex
VEDIO
VEDIO
Afferent pupillary defect • In the absence of an optic nerve lesion in the fellow eye, RAPD
can be demonstrated by swinging flash light
• -ve RAPD in recurrent attacks
Causes:Causes:
• Optic neuropathyOptic neuropathy• Total retinal detachmentTotal retinal detachment• Dense vitreous haemorrhageDense vitreous haemorrhage• Dense amblyopiaDense amblyopia
VEDIO
Contrast sensitivity
• - good for subclinical ON
Optic Disc SwellingOptic Disc Swelling How do you approach? How do you approach?
Papilloedema Papilloedema vsvs Optic Neuritis Optic Neuritis
Papilloeodema Definition , Non-inflammatory swelling of Optic disc Causes1. Raised Intracranial Pressure:
- Space-occupying lesions-Occlusion of :retinal veins cavernous sinus-Other cause.
Optic Neuritis (ON) • Inflammation of optic nerve - ON
• Associated with swollen disc – papillitis
• Normal disc – retro bulbar ON
Papilledema Optic neuritis AION increased ICP Inflammatory swelling Vascular accident (occlusion of
short posterior ciliary artery causing infarction
Brain tumors , hematomas,meningitis
Multiple Sclerosis is highly associated
Hypertension, giant cell arteritis, hypercoagulable state
Bilateral , may be asymmetric
Unilateral Unilateral
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Headache, nausea, vomittingHeadache, nausea, vomittingNo visual loss usually,No visual loss usually, only enlarged blind spot only enlarged blind spot
Retrobulbar pain on ocular Retrobulbar pain on ocular movement, early central movement, early central scotoma, decreased acuity, scotoma, decreased acuity, impaired color vision,impaired color vision,presence of APDpresence of APD
Acute painless visual loss, usually Acute painless visual loss, usually hemialtitudinal defect involving hemialtitudinal defect involving the lower visual fieldthe lower visual field
Variable degree of disc swelling, hemorrhages
Fewer hemorrhages and cotton wool spots
Pale segmental swelling and splinter hemorrhages at its margins
Prognosis usually good if primary cause of increased ICP is treated
Vision usually returns to normal
Poorer prognosis, permanent loss. Second eye is involved in one third of cases.
OPTIC ATROPHYDegeneration of the optic nerveoccurs as an end result of any pathologic process that damages axons
Ophthalmoscopic classification Primary optic atrophySecondary optic atrophyConsecutive optic atrophyGlaucomatous optic atrophy
Primary optic atrophy
Consecutive optic
atrophy
Secondary optic atrophy
Glaucomatous optic atrophy
chalky white or white
Disc appears yellow waxy
dirty white in colour
Pale disc
Margins are sharply outlined
edges are not so sharply defined
Edges are blurred,.
Edges well defined
Lamina cribrosa is clearly seen at the bottom of the physiological cup
physiological cup is obliterated
deep and wide cupping of the optic disc and nasal shift of the blood vessels
Major retinal vessels and surrounding retina are normal
Retinal vessels are attenuated
vessels are attenuated and perivascular sheathing
Normal
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