A&V:14 Disturbances of Vision | 260-288

Question 1

Three divisions of ocular movement abnormalities.

Answer 1

EOM (NMJ) to infranuclear
supranuclear/intranuclear
strabismus

Question 2

define vergence movements

Answer 2

fusion (convergence/divergence and accomodative movements

Question 3

define stereopsis

Answer 3

depth preception

Question 4

define saccadic movements

Answer 4

rapid VOLUNTARY conjugate movements in order to rapidly change ocular fixation (700 deg./s)

Question 5

Breifly describe the neurophysiology of saccades

Answer 5

pulse-step , pulse to move eyes and step to maintain firing at the gaze holding position.

Question 6

Define pursuit movements

Answer 6

stimulated by a moving target, keep moving target on fovea

Question 7

what is a “saccadic” pursuit

Answer 7

moving target begins to slip off fovea and the saccades causes eye to catch up (refixate)

Question 8

define optokinetic nystagmus

Answer 8

cycles of pursuit and refixation

Question 9

what does the VOR do ?

Answer 9

with quick movement the of head the point of fixation is maintained by producing an opposing force to the direction of head turn.

Question 10

describe the 5 step pathway of a horizontal gaze

Answer 10

c/l frontal lobe (area 8) –> decussation to i/l pontine PPRF –> CNVI –> i/l lat. rectus and c/l CNIII –> from CNIII to med. rectus

Question 11

Major difference between horizontal gaze and vertical gaze

Answer 11

Horizontal gaze is generated unilaterally while vertical gaze is generated bilaterally

Question 12

three integrated structures of vertical gaze

Answer 12

riMLF projectin i/l to CNIII and interstitial nucleus of Cajal which projects c/l through posterior commissure to CNIII