P Lab: eye movement Flashcards
Vergence
diconjugate eye movement decreasing the inrer-ocular angle, in order to be able to look at near-by objects
Divergence
Disconjugate eye movements increasing the inter-ocular angle, in order to bring the eye back to infinity view position from a converged state
Saccade
a rapid and conjugate eye movement to look at objects of interest
Optokinetic nystagmus
reflec eye movements elicited by large field visual motion
cannot be suppressed by volition
Vestibular nystagmus
reflex eye movement elicited by head or whole body rotation
Stribismus
misalignment of the eye
Occulomotor apraxia
absence of, or a defect in the control of voluntary purposeful eye movements
Oculomotor palsy
Closed eyelid
elevation of the eye outward and downward
enlarged pupil (no reactiont to normal light)
Saccade test
looking rapidly at a succession of tagets in the enviroment
lesion can be in the saccade generator network or frontal eye field (post cardiac surgery)
Ocular follwoingt test, smooth pursuit test
ocular following of a slow moving target
(oclomotor vermis, V5/MT-MST)
Test all oculomotor muscles
Poor performace is typically caused by damage to abducens internuclear
Vergence/divergence test
looking at a very close target
(affected during internuclear opthalmoplegia)
Test medial recti and lateral recti
(abducens nerve)
Optokinetic test
following a large field moving targer
(affected with blindness or lesion of V5)
Vestibulo-ocular reflex test
reflec eye movements following exposure on a rotating chair
What medical conditions cause vestibulo nystagmus?
Imbalance in vestibular circuits
Labyrinth damage (hemilabyrinthectomy)
BBPV
How do optokinetic and vestibular mystagmus interact
They are complementary/synergistic
