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Optic Nerve Anatomy Quiz
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Optic Nerve Anatomy Quiz

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Questions and Answers

What is the primary consequence of disc hemorrhages on myelin?

  • Gliotic tissue with conduction properties
  • Segmental or diffuse optic disc pallor
  • Substitutive tissue with enhanced conduction properties
  • Substitutive tissue lacking conduction properties (correct)

    • What is the most common type of ischemic optic neuropathy?

  • Non-Arteritic (NAION) (correct)
  • Compressive optic neuropathy
  • Arteritic (AAION)
  • Neurogenic optic neuropathy

    • What is the primary cause of Non-Arteritic Ischemic Optic Neuropathy (NAION)?

  • Hypoperfusion or Non-perfusion of the optic nerve head (correct)
  • Diabetes mellitus
  • Mechanical mass effect
  • Chronic compression of the optic nerve

    • What is the most common symptom of compressive optic neuropathy?

    <p>Fluctuations in visual acuity</p> Signup and view all the answers

    What is the significance of optociliary shunt vessels in the optic disc?

    <p>Indicates chronic compression</p> Signup and view all the answers

    What is the primary goal of diagnosing and treating compressive optic neuropathy?

    <p>To preserve the patient's vision and medical health</p> Signup and view all the answers

    What is the average age of onset for patients with NAION?

    <p>60 years</p> Signup and view all the answers

    What is the primary cause of AAION?

    <p>Vasculitis of the short posterior ciliary vessels</p> Signup and view all the answers

    What is the characteristic of the disc in the fellow eye of a patient with NAION?

    <p>Small, crowded, elevated with blurry margin</p> Signup and view all the answers

    What is the typical treatment for AAION?

    <p>Intravenous methylprednisolone</p> Signup and view all the answers

    What is the pathophysiological process underlying AION associated with Sarcoidosis?

    <p>Infiltration process</p> Signup and view all the answers

    What is the most common symptom of AAION?

    <p>Headache</p> Signup and view all the answers

    What is the approximate number of nerve fibers present in each human optic nerve?

    <p>1.2 million</p> Signup and view all the answers

    What is the function of the optic chiasm?

    <p>A site where fibers from the temporal visual fields of both eyes undergo partial decussation</p> Signup and view all the answers

    Which part of the retina lacks photoreceptors resulting in the eye's blind spot?

    <p>Optic disc</p> Signup and view all the answers

    What is the final destination of the nerve fibers in the optic pathway?

    <p>Visual cortex</p> Signup and view all the answers

    Which meningeal layer is the outermost layer that ensheathes the optic nerve?

    <p>Dura</p> Signup and view all the answers

    What type of signals are transmitted through the optic nerve?

    <p>Electrical signals</p> Signup and view all the answers

    What is the characteristic of reduction in contrast sensitivity in compressive optic neuropathy?

    <p>Painless, unilateral or asymmetric, and variable</p> Signup and view all the answers

    What is the most common cause of traumatic optic neuropathy?

    <p>Motor vehicle accident</p> Signup and view all the answers

    What is the characteristic of infiltrative optic neuropathy?

    <p>Bilateral disc swelling due to increased intracranial pressure</p> Signup and view all the answers

    What is the treatment for traumatic optic neuropathy?

    <p>Intravenous steroid followed by oral prednisone</p> Signup and view all the answers

    What is the characteristic of compressive optic neuropathy?

    <p>Optic nerve compression due to tumors or non-neoplastic lesions</p> Signup and view all the answers

    What is the cause of papilledema?

    <p>All of the above</p> Signup and view all the answers

    What is the characteristic feature of Terson syndrome?

    <p>Preretinal hemorrhages</p> Signup and view all the answers

    Which of the following is NOT a common symptom of cerebral venous sinus thrombosis?

    <p>High fever</p> Signup and view all the answers

    What is the typical pupillary response in AION?

    <p>Afferent pupillary defect (APD)</p> Signup and view all the answers

    Which of the following conditions is commonly associated with loss of consciousness?

    <p>AION</p> Signup and view all the answers

    What is the significance of fundoscopic examination in AION?

    <p>It is normal in the acute phase</p> Signup and view all the answers

    Which of the following is a common feature of papilledema?

    <p>Bilaterally swollen, hyperemic discs</p> Signup and view all the answers

    Study Notes

    Optic Nerve Anatomy

    • The optic nerve is the second of twelve paired cranial nerves.
    • Each human optic nerve contains 1.2 million nerve fibers.
    • These fibers are axons of the retinal ganglion cells of one retina.
    • The optic nerve is ensheathed in all three meningeal layers (dura, arachnoid, and pia mater).
    • The optic nerve leaves the orbit (eye socket) via the optic canal, running postero-medially towards the optic chiasm.
    • In the optic chiasm, there is a partial decussation (crossing) of fibers from the temporal visual fields (the nasal hemiretina) of both eyes.

    Optic Nerve Physiology

    • Light stimulation of the retina travels via the optic nerve as electrical signals to the visual cortex and is ultimately interpreted as visual images.
    • The eye's blind spot is a result of the absence of photoreceptors in the area of the retina where the optic nerve leaves the eye.
    • Symptoms of optic neuropathy include:
      • Reduction in visual acuity
      • Reduction in color vision
      • Reduction in contrast sensitivity
      • APD (afferent pupillary defect)
      • Associated ocular inflammation (iritis, vitritis, pars planitis, intermediate uveitis) can be present depending on the etiology

    Infiltrative Optic Neuropathy

    • Causes:
      • Tumors (intra-cranial, chiasmal, or optic nerve tumors)
      • Non-neoplastic lesions (retrobulbar hemorrhage, aneurysm, mucocele, orbital apex syndrome)
    • Compression can be unilateral or bilateral
    • Treatment: directed at the underlying cause

    Traumatic Optic Neuropathy

    • Classically divided into:
      • Direct injury: external object penetrates the tissues and impacts the optic nerve
      • Indirect injury: collision to the skull and the energy is absorbed by the optic nerve
    • Causes:
      • Motor Vehicle Accident (MVA), most common cause
      • Bicycle Fall
      • Assault

    Papilledema

    • Bilateral disc swelling due to increased intracranial pressure
    • Causes:
      • Primary and metastatic intracranial tumors
      • Hydrocephalus
      • Pseudotumor cerebri: often occurs in young, overweight females
      • Subarachnoid hemorrhage: severe headache, may have preretinal hemorrhages (i.e., Terson syndrome)
      • Arteriovenous malformation
      • Brain abscess: often produces high fever
      • Meningitis: fever, stiff neck, headache
      • Encephalitis: often produces mental status abnormalities
      • Cerebral venous sinus thrombosis

    Ischemic Optic Neuropathy

    • Non-Arteritic (NAION) 95%:
      • Cause: Hypoperfusion or Non-perfusion of the optic nerve head
      • Risk factors: Diabetes mellitus, Hypertension, Hypercholesterolemia, Smoking
    • Arteritic (AAION) 5%:
      • Cause: Vasculitis of the short posterior ciliary vessels supplying the optic nerve head leading to ischemia
      • Associated with giant cell arteritis
      • Mean age of onset: 70 years
      • Symptoms: Severe visual loss, developing over hours to days

    Management

    • Treatment should be directed at the underlying cause of the increased intracranial pressure
    • NAION: observe, control risk factors
    • AAION: high-dose (steroid) oral prednisone or intravenous methylprednisolone followed by a course of oral prednisone

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    Related Documents

    Optic Neuropathy.pdf

    Description

    Test your knowledge of the optic nerve, including its anatomy, structure, and function. Learn about cranial nerve II, the optic canal, and the meningeal layers. Assess your understanding of the optic nerve's role in vision.

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