Chapter 9: Ocular Motility Flashcards
Ocular Motility
The evaluation of eye movements and their disorders
Rectus muscles
The 6 muscles that are attached to each eye to aid in movement
3 planes of movement:
1) Horizontal
2) Vertical
3) Torsional
Superior Rectus Muscle
EOM attached to the upper side of the globe
3 functions:
1) Supraduction
2) Incyclotorision
3) Adduction
Innervated by Oculomotor nerve
Inferior Rectus Muscle
EOM attached to the underside of the globe
3 functions:
1) Infraduction
2) Excyclotorsion
3) Adduction
Innervated by the Oculomotor nerve
Medial Rectus Muscle
EOM attached to the inner side of the globe
Function
1) Adduction
Innervated by the Oculomotor nerve
Lateral Rectus Muscle
EOM attached to the outer part of the globe
Function:
1) Abduction
Innervated by the Abducens nerve
Superior Oblique Muscle
EOM attached to the upper/outer side of the globe
3 Functions:
1) Incyclotorsion
2) Depression
3) Abduction
Innervated by the Trochlear nerve
Inferior Oblique Muscle
EOM attached to the lower, outer part of the globe
3 functions:
1) Excyclotorsion
2) Elevation
3) Abduction
Innervated by the Oculomotor nerve
Primary Action
The strongest action of the EOM
Secondary Action
The intermediate action of the EOM
Tertiary Action
The weakest action of the EOM
Cardinal Positions of Gaze
The 6 points to which a patient’s eyes are directed, t test the major function of each EOM
Positions:
Right and Up
Right
Right and Down
Left and Up
Left
Left and Down
Agonist
The muscle that moves the eye into a particular direction of gaze
Antagonist
The muscle in the same eye that opposes the action of the agonist muscle action
Ductions
Eye movements of a single eye
Versions
Eye movements of both eyes at the same time
Oculomotor Nerve
The 3rd cranial nerve, which supplies the impulses that activate the superior, medial, and inferior rectus muscles, inferior oblique muscles, as well as the levator palpebrae and the pupil
Trochlear Nerve
The 4th cranial nerve, which supplies the impulses to the superior oblique muscle.
Abducens Nerve
The 6th cranial nerve, which supplies impulses to the lateral rectus muscle
Conjugate
When the eye muscles move in the same direction,
Disconjugate
When the eyes move in opposite directions simultaneously. The most important example of this is convergence
Convergence
The coordinated movement of both eyes inward in order to view close by objects
Strabismus
A misalignment of the eyes that may cause vision to be disturbed, and occurs when the EOMs do not work in a coordinated manner
Cominant
A strabismus that is the same in all fields of gaze
Incominant
A strabismus that has a different deviation in various gaze directions typically caused by either restriction or paralysis of EOMs
Exo-
The outward deviation of the eye
Eso-
The inward deviation of the eye
Hypo-
The downward deviation of the eye
Hyper-
The upward deviation of the eye
Manifest
An abnormal eye alignment that is consistently present
Latent
An abnormal eye alignment that is present only when fixation is interrupted
Esotropia
The inward deviation of the eye in which the misalignment of the eye is present even when uncovered
Esophoria
The inward deviation of the eye tat is present only when one eye is covered
Corneal Light Reflex
A simple way to check eye alignment by observing how light reflects off of the corneas
Also called the Hirschberg test
Hirschberg Test
A simple test for eye alignment. If the reflection of the light in each cornea is centered in the pupil, then there is alignment
Krimsky Test
A medical procedure to measure the angle of strabismus in patients with a horizontal strabismus
A prism is placed in front of a patient’s eye to correct the corneal light reflex
Cover-Uncover Testing
A test performed by alternating covering and uncovering each eye to determine if a patient’s eyes are misaligned (tropias)
Alternate Cover Testing
A test performed by placing an occluder over one eye and then moving it to the other eye slowly in order to detect a tendency for the eyes to deviate while under the occluder (phorias)
Prism and Alternative Cover Testing
A test to measure the quantity of ocular misalignment using prisms and an occluder
Fusion
The blending by the brain of the separate images received by the 2 eyes so that a single image is perceived even when the eyes move
Diplopia
Double vision, which can be cause by either strabismus or another eye condition
Suppression
The brain’s mechanism to avoid double vision by ignoring one eye
The brain loses this ability after childhood
Amblyopia
Decreased vision present without apparent abnormalities in the ocular anatomy and uncorrectable by spectacles or contact lenses. This results visual deprivation in early childhood
Stereopsis
3D visual perception
Titmus Stereopsis Test
A test for determining whether the patient has fine depth perception in terms of binocular cooperation
