Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cornea > Optic Nerve Disorders > Flashcards

Optic Nerve Disorders Flashcards

1
Q

Do Schwann cells or Oligodendrites form the myelin sheath around the optic nerve?

A

Oligodendrites.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 3 basic anatomic “rules” of the orientation of the nerve fibers within the optic chiasm?

A
  1. Nasal retinal fibers of each eye cross in the chiasm into the contralateral optic tract.
  2. Lower retinal fibers project through the chiasm to lie laterally in the optic tract; upper retinal fibers lie medially.
  3. Inferonasal retinal fibers cross in the chiasm but course anteriorly (~4mm) in the contralateral optic nerve (Wilbrand’s Knee).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

The bulk of the blood supply to the optic nerve head is from what artery/ies?

A

Short posterior ciliary arteries (extension of the ophthalmic artery).
*The RNFL blood supply is derived from the CRA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the most common VF defect seen in someone with papilledema?

A

Enlarged blind spot.
*Vision is typically okay although some patients may report temporary “graying of vision” that completely resolves. Vision is usually affected in the chronic or atrophic stage of papilledema.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Does papilledema cause nerve palsies?

A

Papilledema may lead to an abducens palsy either unilateral or bilateral. This is due to compression of the nerve against the petrous temporal bone at the base of the skull.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Idiopathic Intracranial Hypertenison is characterized by?

A
  1. Increased incranial pressure
  2. Normal or small-sized ventricals on neuroimaging
  3. Normal CSF composition
  4. Papilledema
  5. Lack of any neurologic deficits that cannot be attributed to elevated intracranial pressure.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What percentage of patients with recent onset optic neuritis presented with optic disc edema or papillitis (according to the ONTT)?

A

1/3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name 3 mimickers of Optic Neuritis and how do you distinguish them from optic neuritis?

A
  1. Nonarteritic Ischemic Optic Neuropathy - Usually seen in older patients and they do not present with pain on eye movement. They usually have other systemic conditions that predispose them to an ION.
  2. Leber’s Hereditary Optic Neuropathy - seen in the same age population but they lack pain on eye movement and visual recovery is poor.
  3. Optic Nerve Sheath Meningioma - 1/4 of these patients have optociliary shunt vessels and the disc edema typically lasts for more than 6-8 weeks.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What percentage of patients will show improvement in VA following a NAION?

A

46%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

List some atypical features that should lead a clinician from the diagnosis of idiopathic NAION to another diagnosis…

A
  1. Patient is younger than 50
  2. Absence of typical risk factors - hypertension, DM, High cholesterol
  3. Patient has light perception (typically NAION causes decreased vision between 20/25-20/200)
  4. Ant/Posterior cells
  5. No visual improvement after 3 mos.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

List some differential diagnosis if the patient presents with atypical characteristics of a ION.

A

AION, Optic Neuritis, LHON, Sarcoidosis, Infiltrative optic neuropathy (leukemia, lymphoma), Compressive optic neuropathy (Optic nerve sheath meningioma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

List some ways to differentiate ION with optic neuritis

A

Age of patient, pain on movement (67% with ON, 8% with ION), VF defect (central scotomas in ON, Altitudinal in ION), VA recovery, MRI of orbit (shows thickening in ON)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are some common systemic symptoms of a patient with GCA

A

Jaw pain while eating, headache, polymyalgia rheumatica, scalp tenderness, anorexia, weight loss, fever

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

50% of optic nerve gliomas in children are due to what systemic condition?

A

Neurofibromatosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How far (in mm) must a pituitary adenoma grow before it starts to compress the visual system?

A

~10mm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is pituitary apoplexy?

A

Sudden expansion of an existing pituitary adenoma due to intratumoral hemorrhage or infarction.

17
Q

What is the order of involvement of the rectus muscles affected in Thyroid-Related Orbitopathy?

A

Inferior - Medial - Superior - Lateral

18
Q

List some Non-thyroid causes of extraocular muscle enlargement

A
  1. Inflammatory: Sarcoid, Wegener’s, Crohn’s, Whipple’s, SLE, RA, Idiopathic Orbital Inflammation
  2. Vascular: CCF, AV Malformation
  3. Neoplastic: Local or Metastasis
  4. Infectious: Viral, bacterical, fungal, parasitic, Orbital Cellulitis
  5. Deposition: Amyloid
  6. Traumatic
  7. Iatrogenic: Following orbital/sinus surgery. Drug Induced - lithium, chloroquine
  8. Congenital: Fibrosis syndromes, NF
  9. Miscellaneous: Acromegaly, Vit E deficiency
19
Q

List some ophthalmoscopic features seen in patients with pseudopapilledema

A
  1. Elevated disc; obscured margins
  2. Absence of central cup
  3. Vascular anomalies with increased branching
  4. Normal NFL; disc transilluminates
  5. Presence of a SVP is strongly suggestive of pseudopapilledema
  6. Hyaline bodies
  7. Hyperopia
  8. Small scleral canal
  9. Non-hyperemic disc
  10. No Hemes, Exudates, CWS
20
Q

What is the most frequent cause of pseudopapilledema?

A

Optic Nerve Head Drusen

  • 75% are bilateral
  • Seen in predominately caucasians
  • Lumpy-Bumpy appearance
  • SVP often present
  • Occasionally associated with hemorrhages
  • Up to 73% with visible drusen have a VF defect with slow rate of progression - most often the loss is nasally.
  • May cause subretinal, intraretinal hemorrhages or peripapillary choroidal neo.
21
Q

What syndrome is characterized by panhypopituitarism, BONH (bilateral optic nerve hypoplasia) and midline brain abnormalities?

A

De Morsier’s - occurs in ~10% of children with BONH

22
Q

What funduscopic finding is reported in children of insulin-dependent diabetic mothers?

A

Superior segmental optic hypoplasia

  • Superior entrance of the CRA
  • Pallor of superior disc
  • Superior peripapillary halo
  • Thinning of the superior RNFL
23
Q

What is the proposed origin of retinal edema seen in optic nerve pits?

A

Vitreous or CSF

24
Q

Astrocytic Hamartomas are large, multilobulated deposits on the surface of the disc or retina and are commonly seen in patients with what systemic condition?

A

Tuberous Sclerosis - multi-system condition where non-malignant tumors grown in various organ systems.
*Less frequently seen in neurofibromatosis

25
Q

List some diagnostic criteria that characterize dominant optic atrophy

A
  1. AD inheritance - emphasize examining relatives (95% penetrance)
  2. Insidious onset, usually before 10 yo
  3. Bilateral, often asymmetric VA loss
  4. Usually mild but occasionally moderate VA reduction (20/40 - 20/400)
  5. Central or centrocecal scotomas
  6. Tritan (B-Y) has been described but severe generalized dyschromatopsia, regardless of VA level, is the most common
  7. Temporal disc pallor, often with a triangular area of temporal excavation
26
Q

What are the classic ophthalmoscopic findings in acute LHON (Leber’s Hereditary Optic Neuropathy)?

A
  1. Circumpapillary telangiectasia microangiopathy
  2. Swelling of the NFL around the disc
  3. Absence of leakage from the disc or peripapillary region on angiography
    * Patients often males (85%) btw 15-35 yo
    * Rapid loss of central vision with color vision and VF affected early
27
Q

Is Toxic/Nutritional Optic Neuropathy usually unilateral or bilateral? Describe some additional findings of a patient suffering from this type of neuropathy

A

Typically bilateral and findings are symmetric, VA decrease ranges from 20/30-20/200, peripheral VF is spared, dyschromatopsia is present, APD is not present, central/centrocecal scotomas, optic nerve may appear normal/mildly swollen/pale.

28
Q

List some antibiotics associated with toxic optic neuropathy

A
  1. Ethambutol - used to treat tuberculosis
  2. Clioquinol and iodochlorohydroxyquinoline - amebicidal agents
  3. Dapsone - used in combination to treat leprosy
  4. Chloramphenicol - broad spectrum AB - known to cause aplastic anemia
  5. Linezolid - powerful Ab used to treat serious infections by gram-positive bacteria
29
Q

List some “toxins” associated with optic neuropathy

A
  1. Methanol - odorless liquid present in antifreeze, copying fluid, washer fluid, paint remover.
  2. Ethylene Glycol - results from ingestion of antifreeze
  3. Solvents (Toluene, Styrene)
  4. Carbon Monoxide
30
Q

LIst some immunosuppressants/immunomodulators associated with optic neuropathy

A
  1. Cyclosporine - used in organ transplant patients, RA, atopic dermatitis, psoriasis
  2. Tacrolimus (FK506) - organ transplants, eczema, vitiligo
  3. Alpha interferon 2-B - antiviral used in treatment of Hep C, Hep B, leukemia, multiple myeloma, melanoma, lyphoma
31
Q

LIst some chemotherapeutic agents associated with optic nerve toxicity

A
  1. Cisplatin and Carboplatin - metal alkylating agents used to treat a variety of cancers
  2. Vincristine - used widely to tx lymphoma
  3. 5-fluorouracil - cancer drug
32
Q

Miscellaneous drugs that cause optic neuropathy

  1. Disulfiram
  2. Cimetidine
  3. Benoxaprofen
  4. Paclitaxel
  5. Chlorpropamide
  6. Combined use of melatonin, sertraline and high protein diet
  7. Vigabatrin
A
  1. aka Antabuse - used to treat alcoholism
  2. Cimetidine aka Tagamet - used to treat peptic ulcers and heartburn
  3. Benoxaprofen aka Oraflex - NSAID - no longer on the market
  4. Paclitaxel aka Taxol - anti-cancer drug
  5. Chlorpropamide - used to treat type II DM - no longer used
  6. Melatonin, Zoloft (SSRI) - causes melatonin/dopamine imbalance in the retina
  7. Vigabatrin aka Sabril - anti-epileptic drug to treat seizures
33
Q

List some medications that may induce optic neuropathies by a non-toxic mechanism (caused by increased ICP, ischemia or autoimmune rxn)

A
  1. Sildenafil aka Viagra, Tadalafil aka Cialis - effect on the ON is due to a decrease in perfusion or arterial hypotension
  2. Infliximab aka Remicade - used to treat autoimmune diseases. Possibly increases risk of demyelination
  3. Vitamin A and Tetracyline derivatives (Retinoids), Cyclosporine, Lithium, Ketoconazole and Nalidixic Acid - medications associated with elevated ICP and papilledema with HAs and OMN palsies
34
Q

Which medication, known to cause vortex epitheliopathy of the cornea and anterior subcapsular lens opacities, has been associated with toxic optic neuropathy?

A

Amiodarone - anti-arrhythmic used to treat ventricular tachycardia and fibrillation. Patients may develop a unilateral NAION - this optic neuropathy is NOT considered an adverse drug reaction. Other patients develop a neuropathy that has a more insidious onset and is more often bilateral - this is thought to be the result of a direct toxic effect on the ON.

Cornea (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions