part 12 Flashcards
ductions
one eye motion
direction of ductions
abduction- moves away from
adduction- moves towards
elevation, depression
intorsion, extorsion
vergence
disconjunctive eye movements
eyes move in opposite direction called vergence when normal
convergence
both eyes look at nose
divergence
both eyes look away from nose
what plane has no vergence
vertical
names for when eyes are rotating (vergence)
incyclovergence
excyclovergence
Version circuits
conjugate eye movements (2 eyes move in same dirrection)
herings law of equal innervation
due to innate connections in which the eye muscles responsible for eye movement are equally innervated
what is connection behind version circuits
abducens nuclues and intersitital nuclei
horizontal plane version circuits
dextral or leveversion
vertical plane of version circuits
elevate or depress
version/tilt procedure
hold patient head and have them tilt head to side up and down, L and R
- look for nystagmus and note direction
- nonsychrnonic eye movement
lack of counter tilt
ocular alignment
test of skew
how do eyes hold gaze when covered and uncovered (switching between eyes)
look for vertical corrective movement of eyes as uncovered
interpret as vertical misalignment of eyes (central)
Tropia
deviation of visual axes during binocular observation of target Cover uncover test (one eye) when eye covered does the uncovered eye move towards nose (isotropia)
phoria
deviation of visual axes during monocular observation of target
- when eye is covered it deviates externally
- when uncovered moves back internally
hypo/hyperphoria
is a skew and a sign of abnormal central pathology
where is the ocular tilt reaction imballance coming from
in otolithic pathways anywhere from vestibular organs to midbrain
ocular tilt reaction triad
- skew deviation- vertical misalignment of eyes
- head tilt toward trophic eye
- ocular torsion- top of both eyes rotated towards lower ear
- if all 3 present ocular tilt reaction complete, some partial forms exist
ocular tilt reaction causes
brainstem or unilateral peripheral vestibular lesion
- site of head tilt is site of lesion
abnormality- internuclear opthalamoplegia
gaze in unilateral MLF inactivation
internuclear opthalamoplegia- unliateral
MLF site of lesion= site with adduction slow
eye that moves slow towards the nose on same side with lesion
internuclear opthalamoplegia- bilateral
MLF site of lesion=site with adduction slow
both eyes not fully adducting, both show nystagmus and slow adduction
vergence circuits purpose
disconguate eye movements
- align fovea of each eye with targets at different distances from observer through saccades
integrated at level of superior colliculus and lateral geniculate nucleus
vergence circuit procedure
have patient look at fingers 2m from nose, focus on finger that is up (quick 1 up 1 down)
dynamic if fingers move
Look for convergence and divergence of eyes, conjugate eye movement and pupillary constriction
abnormalities are central problem
neural integrator
gaze holding
ability to maintain fixation once visual target acquired
abnormality- leaky integrator
leaky integrator
not maintain eyes on target once acquired OR eyes get to target but slip away then a corrective saccade brings back on target
