#4- Neurophysiology of Ocular Motility

Question 1

At what age does Alignment of eyes becomes stable: 2, 4, 6, 8 mos?

Answer 1

4 months

Question 2

At what age does accommodation of eyes occur 2, 4, 6, 8 mos?

Answer 2

4 months

Question 3

At what age are eyes 2/3 of adult size?: 2, 4, 6, 8 mos?

Answer 3

6 months

Question 4

At what age is vision 20/20?: 2, 4, 6, 8 mos?

Answer 4

8 months

Question 5

what is the qualitative vision test for infants

Answer 5

fixation and following-

Question 6

3 examples of quantitative vision tests in infants

Answer 6

1. preferential looking - prefer patterns
2. optokinetic nystagmus - Passing objects (lines) evoke a prsuit and nystagmus response
3. Visual evoked potential
   Computer extracts a stimulus-related EEG signal from scalp electrodes

Question 7

The Vestibulo-Ocular Response (VOR) fires at what 4 nuclei?

Answer 7

1. Vestibular ganglion (endolymph mvmt)
2. Vestibular nuclei (in brainstem)
3. Ipsilateral CN III nucleus, 4. Contralateral CN VI nucleus)

Question 8

where do signals for the saccidic system originate, and what sided saccades do they control (ipisi- or contra-lateral)

Answer 8

Visual cortex (and FEF) control contralateral saccades

Question 9

What structurecontrols ipsilateral smooth pursuits?

Answer 9

Parieto-Occipital-Temporal Junction

Question 10

What nuclei controls horizontal gaze? and what nucleus does it project output neurons to?

Answer 10

parapontine reticular formation projects to ipsilateral abducens nucleus

Question 11

what sx are seen in I/L, C/L and convergence in Intranulcear Opthalmoplegia ?

Answer 11

I/L adduction defect
C/L abduction nystagmus
convergence is normal

Question 12

Cause of ION:

1. general
2. young
3. old
4. others

Answer 12

1. general = demyelination
2. young = multiple sclerosis (pathognomonic)
3. Old = stroke
4. others = Toxicity, EtOh (wernicke’s)

Question 13

Vertical gaze controlled by what 2 nuclei/pathway?

□

Answer 13

Interstitial nucleus of Cajal

Rostral interstitial MLF

Question 14

what is seen in eyes in dorsal-midbrain syndrome?

Answer 14

light-near dissociation- pupils wil constrict upon convergence, but not with light

also- inability to look up quickly

Question 15

Where is ;lesion (specifically) in dorsal midbrain syndrome and what are 2 major causes?

Answer 15

lesions in posterior commissure

caused by pinealomas and shunt malfunctions

Question 16

superior rectus an inferior rectus have what 3 mvmts of eye each?

Answer 16

SR: intort, elevate, adduct

IR: depress, extort, adduct

Question 17

what are 2 causes of strabismus and one result?

Answer 17

CNS lesion (e.g.,tumor) or vision loss may cause strabismus

-may result in vision loss dt ambylopia

Question 18

define esotropia, exotropia, hypertropia

Answer 18

Esotropia: one eye deviated medially
Exotropia: one eye deviated laterally
Hypertropia: one eye up

Question 19

define concomittant and incomittant strabismus

Answer 19

concommitant: same misalignment in all directions of gaze
incommitant: different misalignment in different gazes

Question 20

What type of strabismus is accomodative esotropia? (concommitant or incommitant) and what is it’s pathogenesis?

Answer 20

concommitant strabismus

-caused by blurry vision which causes th child to accommodate which is always accompanied by convergence

Question 21

What is tx for accomodative esotropia?

Answer 21

glasses

Question 22

What is an example of incommitant paralytic strabismus

Answer 22

CN VI palsy

Question 23

When do you need to get MRI to rule out aneurysm in CNIII palsy?

Answer 23

if the pupil is involved

Question 24

How will pt present with CN IV palsy

Answer 24

head tilt to opposite side

Question 25

What is involved in tx of strabismus

Answer 25

treat underlying ambylopia

Question 26

define ambylopia

Answer 26

Decrease in BCVA (best corrected visual acuity) in one or both eyes
(20/20 with glasses is not ambylopia - that is a refractive error)

Question 27

3 causes of ambylopia

Answer 27

strabismus
refractive error
stimulus deprivation

Question 28

gold std tx for ambylopia

Answer 28

patch over normal eye allows stimulation of abnormal eye