OCULAR MOTILITY Flashcards
Sherrington’s Law
Says that agonist and antagonist EOMs of the same eye are reciprocally innervated.
Hering’s law of equal innervation
Synergistic muscles of the two eyes must receive equal innervation. “Yoke muscles”
VOR
Stabilizes images on the fovea during brief head movement.
Eye movement of equal magnitude to head movement but in opposite direction.
-occurs rapidly with very small latency
-300 deg/sec, latency 15msec
Ocillopsia
Sensation of objects moving up and down in the visual field
-acquired nystagmus often report this
Vertigo
Sensation of the body moving around in the environment
Testing Vestibular dysfunction
- oculocephalic testing
- caloric testing
- rotational testing
Jerk nystagmus
Characterized by slow and fast phase.
Pendular nystagmus
even ack and forth movement of the eyes.
Direction of gaze where the nystagmus has the lowest amplitude is
Null point
Direction where the nystagmus changes direction is
The Neutral point
End point nystagmus
Small intermittent conjugate jerk nystagmus apparent in extreme >30 degree from midline, horizontal position of gaze . Less commonly vertical often worse when patient is tired.
Damage to the right FEF results in impaired saccades toward what direction
To the left ‘ the side opposite the lesion ‘ resulting In the eyes turning to the right “toward the side of the lesion”
Pursuits
Are slow
Latency of 125msec and velocity of 50degree/second
- controlled by the Parietal lobe
-Parietal lobe lesion will cause impaired pursuit toward the ipsilateral side.
Cogwheelong
Abnormal pursuit , step like eye movement
Proximal vergence
Degree is small, usually neglected when measuring vergence movement .
-convergence is associated with a person’s awareness of a near target.
