optic nerve: anatomy and disorders

Question 1

most common site of traumatic optic neuropathies

Answer 1

blow to the brow - attached to the dura in the optic canal

Question 2

what do ganglion cells respect in the retina

Answer 2

the horizontal midline

Question 3

what percentage of gnaglion cells duccusate

Answer 3

53% cross

47% remain on same side

Question 4

where is common site of optic nerve constriction

Answer 4

lamina cibrosa

Question 5

what is special about the cup in the disc

Answer 5

devoid of any axons and tissue (white)

Question 6

what is normal cup to disc ratio

Answer 6

0.3

Question 7

what is large cup a sign of

Answer 7

glaucoma

Question 8

5 ways to test optic nerve function

Answer 8

1. central visual acuity
2. RAPD
3. visual fields
4. color testing
5. contrast sensitivity

Question 9

what is an RAPD a sign of

Answer 9

optic nerve damage in that eye - most optic neuropathies are assymetric and thus will have an RAPD

Question 10

3 keys things to assess in the optic nerve clincally

Answer 10

Borders - are they sharp?
Color - pink is normal - is there pallor
Cup - can I see it - ratios

Question 11

what is papilledema

Answer 11

swelling of the optic nerve head due to increased ICP - usually bilateral

Question 12

pathophysio of pappiledema

Answer 12

increase ICP>less space for CSF>CSF excess around optic nevre> swelling

Question 13

when might pappiledema be assymetric

Answer 13

if the nerve is atrophic

Question 14

what is axoplasmic stasis

Answer 14

increase ICP transmitted to optic nerve along meningeal sheaths - stops axoplasmic flow at lamina cibrosa

Question 15

what is diff b/w papill and other optic neuropathies

Answer 15

in pap the visual acuity is pretty normal

Question 16

tests for pappiledma

Answer 16

imaging and if normal > lumbar puncture to meausre pressure and CSF

Question 17

5 other types of optic neuropathies

Answer 17

1. congenital
2. inflammatory
3. ischemic
4. toxic metabolic
5. traumatic

Question 18

2 cats of inflammatory

Answer 18

1. infectious - TB, syphillis, virus

2. non-infectious - idopathic, sacroid, Wegners

Question 19

what is most common optic neuropathies in under/over 50

Answer 19

under - demylenating

over - ischemic

Question 20

2 types of ischemic

Answer 20

arteritic - rarer, but more devastating

non-arteritic - treatable

Question 21

Sx of demylenating (3)

Answer 21

1. unilateral vision loss
2. RAPD
3. pain on eye movements

Question 22

what is relat between optic neuritis and MS

Answer 22

50% will dev. MS - even one lesion is predictive - better MS outcomes though

Question 23

what is non ateritic ischemia

Answer 23

wake up with vision loss and is often altitidunal - hypoperfusion

Question 24

what is giant cell arterititis

Answer 24

inflammation of wall of medium size vessels - occludes lumen

Question 25

Sx of GCA

Answer 25

1. jaw cluadication
2. scalp tenderness
3. headache
   weight loss
   chills

Question 26

markers of GCA

Answer 26

ESR and CRP

Question 27

treatment of GCA

Answer 27

high dose steroids to save vision