Ocular Motility
Tests used to assess ocular motility - ANS-1. Cover Test
-Unilateral CT=distinguishes btw phoria & tropia
-Alternating Ct=assess the direction & amt of phoria or tropia
2. Versions=screening for anomalies of EOMs
Duction - ANS-rotation of one eye under mnocular conditions
Version - ANS-rotations of 2 eyes such that their lines of sight move in the same
direction
Vergence - ANS-rotations of 2 eyes such that their LOS move in opposite directions
LOS - ANS-the line connecting the point of fixation & center of entrance pupil of the eye
Straightforward position - ANS-the position of the eye when the LOS is perpendicular to
the face plane
Primary Position - ANS-sometimes used as a synonym of straightforward position
Cardinal Position - ANS-position of gaze in which one of the EOMs has its main action
Abduction - ANS-temporalward rotation of an eye
Adduction - ANS-a nasalward rotation of an eye
Elevation - ANS-an upward rotation of an eye (supraduction)
Depression - ANS-downward rotation of an eye (Infraduction)
EOM Tests: Version - ANS--used to test for anomalies of EOM: rotations, H patterns,
double H pattern (H pattern most common)
-Screening ONLY; NOT diagnostic
Why is EOM Version test only screening and not diagnostic? - ANS-1. All EOMs (except
MR & LR) have action in more than 1 vector direction
2. Doesn't take into acct which eye is fixating
3. Doesn't take into acct Hering's law
, 4. Many deviations are too small to be easily seen (1mm deviation can range from 12 to
22pd)
Actions of EOMs - ANS--during all version movements all EOMS receive innervation
-All EOMs are in action no matter which field of gaze eyes are in
-Synergistic=some of these multiple actions serve to help the eye obtain a particular
fixation
-Antagonistic=some are actually working against the direction of gaze to help stead
fixation
Herings Law - ANS--for movements of both eyes in same direction, the corresponding
muscles receive approximately similar innervation
-this means that when a eye with a paretic EOM is attempting to fixate in that field of
action the other eye's yoked EOM will overshoot due to the extra effort (innervation)
being expended to fixate the eye in the affected field
Red Lens Test - ANS--used to distinguish comitant vs. incomitant deviations
-uses concepts of crossed & uncrossed diplopia
-If a dissociated eye doesn't line up with a given target, the image of that target will fall
on either nasal or temporal retina
-Red lens placed over OD (left eye is fixating)
Comitancy - ANS--Comitant EOM deviation=angle of deviation is constant in all fields of
gaze
-Incomitant EOM deviation=angle of deviation is NOT constant in all fields of gaze
Red Lens test - ANS--red lens must be dark enough that the pt sees only the red light
thru it, thus preventing peripheral fusion
-conduct versions, instructing the pt to tell you not only when they see the 2 lights but
also the position of the lights to each other and if the distance btw them changes
-do all 6 cardinal points & directly up and down
-repeat with red lens over OS
Red Lens test Interpretation - ANS--if the amt of deviation is constant in all fields of
gaze then the deviation is comitant
-If the amt of deviation is NOT constant then it is incomitant
Parks 2 step and 3 step tests - ANS--confirmation test to detect which EOM is defective
Tests used to assess ocular motility - ANS-1. Cover Test
-Unilateral CT=distinguishes btw phoria & tropia
-Alternating Ct=assess the direction & amt of phoria or tropia
2. Versions=screening for anomalies of EOMs
Duction - ANS-rotation of one eye under mnocular conditions
Version - ANS-rotations of 2 eyes such that their lines of sight move in the same
direction
Vergence - ANS-rotations of 2 eyes such that their LOS move in opposite directions
LOS - ANS-the line connecting the point of fixation & center of entrance pupil of the eye
Straightforward position - ANS-the position of the eye when the LOS is perpendicular to
the face plane
Primary Position - ANS-sometimes used as a synonym of straightforward position
Cardinal Position - ANS-position of gaze in which one of the EOMs has its main action
Abduction - ANS-temporalward rotation of an eye
Adduction - ANS-a nasalward rotation of an eye
Elevation - ANS-an upward rotation of an eye (supraduction)
Depression - ANS-downward rotation of an eye (Infraduction)
EOM Tests: Version - ANS--used to test for anomalies of EOM: rotations, H patterns,
double H pattern (H pattern most common)
-Screening ONLY; NOT diagnostic
Why is EOM Version test only screening and not diagnostic? - ANS-1. All EOMs (except
MR & LR) have action in more than 1 vector direction
2. Doesn't take into acct which eye is fixating
3. Doesn't take into acct Hering's law
, 4. Many deviations are too small to be easily seen (1mm deviation can range from 12 to
22pd)
Actions of EOMs - ANS--during all version movements all EOMS receive innervation
-All EOMs are in action no matter which field of gaze eyes are in
-Synergistic=some of these multiple actions serve to help the eye obtain a particular
fixation
-Antagonistic=some are actually working against the direction of gaze to help stead
fixation
Herings Law - ANS--for movements of both eyes in same direction, the corresponding
muscles receive approximately similar innervation
-this means that when a eye with a paretic EOM is attempting to fixate in that field of
action the other eye's yoked EOM will overshoot due to the extra effort (innervation)
being expended to fixate the eye in the affected field
Red Lens Test - ANS--used to distinguish comitant vs. incomitant deviations
-uses concepts of crossed & uncrossed diplopia
-If a dissociated eye doesn't line up with a given target, the image of that target will fall
on either nasal or temporal retina
-Red lens placed over OD (left eye is fixating)
Comitancy - ANS--Comitant EOM deviation=angle of deviation is constant in all fields of
gaze
-Incomitant EOM deviation=angle of deviation is NOT constant in all fields of gaze
Red Lens test - ANS--red lens must be dark enough that the pt sees only the red light
thru it, thus preventing peripheral fusion
-conduct versions, instructing the pt to tell you not only when they see the 2 lights but
also the position of the lights to each other and if the distance btw them changes
-do all 6 cardinal points & directly up and down
-repeat with red lens over OS
Red Lens test Interpretation - ANS--if the amt of deviation is constant in all fields of
gaze then the deviation is comitant
-If the amt of deviation is NOT constant then it is incomitant
Parks 2 step and 3 step tests - ANS--confirmation test to detect which EOM is defective
