Basic Ocular Motility (Chapter 3) COT
Alt –B Questions And All Correct
Answers
Adduction means the eye is turning - Ans--Inward (toward the nose)
If the eye is depressed, it is - Ans--turning down
Which muscles have only a primary action? - Ans--MR and LR - The only
muscles that have a primary action and no other are the Medial Rectus and
the Lateral Rectus which adduct (MR) and abduct (LR)
Which muscles are elevators? - Ans--IO and SR - IO in adduction & the SR
in abduction
As a tertiary action, both oblique muscles: - Ans--Abduct **Memory hint:
oBliques aBduct
Which muscles are primarily torsional muscles? - Ans--SO and IO - The
primary action of the oblique muscles is torsional. SO intorts and IO extorts
Which muscles act to depress the eye? - Ans--IR and So - IR depresses in
abduction, SO depresses in adduction
Which muscles adduct the eye as a tertiary action? - Ans--SR and IR - Both
vertical rectus muscles have the tertiary action of adduction.
Which is an example of yoked mucles? - Ans--RLR and LMR - Yoked
muscles are muscles in each eye that accomplish the same version
movement.
,Which muscles are synergists for horizontal movement with the MR? -
Ans--SR and IR - a synergist is a muscle in the same eye that assists
another muscle in accomplishing a particular action
Which muscles antagonists for depression with the IR? - Ans--SR and IO -
Both of which are elevators. An Atagonist is a muscle in the same eye that
works against a particular action.
If one eye is obviously turned in, out , up, or down when you perform a
simple external evaluation of the patient, this deviation is - Ans--Tropia -
Unless it is intermittent - a tropia is there all the time.
A phoria is exhibited when: - Ans--Fusion is disrupted. Some phorias "break
down" when the patient is tired. This is actually an intermittent deviation.
(evident only when you cover one eye or otherwise disrupt fusion)
The difference between a phoria and an intermittent tropia is: - Ans--The
phoria usually is controlled and the intermittent tropia is sometimes
controlled.
An adult patient with a tropia has either - Ans--Diplopia or suppression (An
adult with a crossed eye either has learned to suppress the image from the
eye that is not fixating or has double vision. Usually suppression is learned
in childhood as the visual system is developing; the brain learns to ignore
the image from a crossed eye. In cases where strabismus occurs as an
adult diplopia occurs because the brain does not know how to suppress a
second image. It is not a given that amblyopia or anisometropia exist,
although they might. Fusion and stereopsis can occur only when both eyes
are working together, looking at the same object)
An intermittent horizontal tropia might be aggravated by all of the following
except:
a. inattention
b. reading
c. illness
d. fatigue - Ans--b. Reading would encourage fusion (at lease until fatigue
sets in) as it causes convergence.
, Your patient has an exodeviation that is more divergent at near than at a
distance. This is evidence of: - Ans--convergence insufficiency - If
convergence is insufficient, the patient is not able to pull the eyes inward for
near viewing. Thus, the deviation is greater at near that at a distance. Note:
Convergence insufficiency also can occur in orthophoria.
Your patient has an exodeviation that is worse at near than at a distance.
This is classified as - Ans--convergence excess - A convergence excess
means that the eyes overconverge for near viewing. Thus, an esotropia
would be worse at near in this situation.
A and V patterns are types of horizontal deviations that - Ans--vary in up and
down gaze - In an A pattern, the eyes are more converged in upgaze and
more diverged in downgaze. A V pattern is more diverged in upgaze and
more converged in downgaze. The can be measured with prisms.
The most common cause of a V pattern is - Ans--Overactive IO - The
secondary and tertiary actions of the IO are elevation and abduction.
Because the IO has its action in upgaze, an overaction would likely increase
abduction, hence the V pattern.
Which pattern is most common - Ans--V pattern ET - In order of decreasing
occurrence:
V pattern ET
V pattern XT
A pattern ET
A pattern XT
Anisometropia at birth is more likely to result in - Ans--Exotropia -
Congenital anisometropia (unequal refractive errors) leads to amblyopia.
The eye that requires the least amount of accommodation for the best vision
is the eye that will be used. There is a general tendency for an amblyopic
eye to drift out (ie, be exotropic), rather than in. (Obviously, this is not always
the case, but it is the most common.)
All of the following are commonly associated with horizontal deviations
except:
a. adult-onset blindness in one eye
Alt –B Questions And All Correct
Answers
Adduction means the eye is turning - Ans--Inward (toward the nose)
If the eye is depressed, it is - Ans--turning down
Which muscles have only a primary action? - Ans--MR and LR - The only
muscles that have a primary action and no other are the Medial Rectus and
the Lateral Rectus which adduct (MR) and abduct (LR)
Which muscles are elevators? - Ans--IO and SR - IO in adduction & the SR
in abduction
As a tertiary action, both oblique muscles: - Ans--Abduct **Memory hint:
oBliques aBduct
Which muscles are primarily torsional muscles? - Ans--SO and IO - The
primary action of the oblique muscles is torsional. SO intorts and IO extorts
Which muscles act to depress the eye? - Ans--IR and So - IR depresses in
abduction, SO depresses in adduction
Which muscles adduct the eye as a tertiary action? - Ans--SR and IR - Both
vertical rectus muscles have the tertiary action of adduction.
Which is an example of yoked mucles? - Ans--RLR and LMR - Yoked
muscles are muscles in each eye that accomplish the same version
movement.
,Which muscles are synergists for horizontal movement with the MR? -
Ans--SR and IR - a synergist is a muscle in the same eye that assists
another muscle in accomplishing a particular action
Which muscles antagonists for depression with the IR? - Ans--SR and IO -
Both of which are elevators. An Atagonist is a muscle in the same eye that
works against a particular action.
If one eye is obviously turned in, out , up, or down when you perform a
simple external evaluation of the patient, this deviation is - Ans--Tropia -
Unless it is intermittent - a tropia is there all the time.
A phoria is exhibited when: - Ans--Fusion is disrupted. Some phorias "break
down" when the patient is tired. This is actually an intermittent deviation.
(evident only when you cover one eye or otherwise disrupt fusion)
The difference between a phoria and an intermittent tropia is: - Ans--The
phoria usually is controlled and the intermittent tropia is sometimes
controlled.
An adult patient with a tropia has either - Ans--Diplopia or suppression (An
adult with a crossed eye either has learned to suppress the image from the
eye that is not fixating or has double vision. Usually suppression is learned
in childhood as the visual system is developing; the brain learns to ignore
the image from a crossed eye. In cases where strabismus occurs as an
adult diplopia occurs because the brain does not know how to suppress a
second image. It is not a given that amblyopia or anisometropia exist,
although they might. Fusion and stereopsis can occur only when both eyes
are working together, looking at the same object)
An intermittent horizontal tropia might be aggravated by all of the following
except:
a. inattention
b. reading
c. illness
d. fatigue - Ans--b. Reading would encourage fusion (at lease until fatigue
sets in) as it causes convergence.
, Your patient has an exodeviation that is more divergent at near than at a
distance. This is evidence of: - Ans--convergence insufficiency - If
convergence is insufficient, the patient is not able to pull the eyes inward for
near viewing. Thus, the deviation is greater at near that at a distance. Note:
Convergence insufficiency also can occur in orthophoria.
Your patient has an exodeviation that is worse at near than at a distance.
This is classified as - Ans--convergence excess - A convergence excess
means that the eyes overconverge for near viewing. Thus, an esotropia
would be worse at near in this situation.
A and V patterns are types of horizontal deviations that - Ans--vary in up and
down gaze - In an A pattern, the eyes are more converged in upgaze and
more diverged in downgaze. A V pattern is more diverged in upgaze and
more converged in downgaze. The can be measured with prisms.
The most common cause of a V pattern is - Ans--Overactive IO - The
secondary and tertiary actions of the IO are elevation and abduction.
Because the IO has its action in upgaze, an overaction would likely increase
abduction, hence the V pattern.
Which pattern is most common - Ans--V pattern ET - In order of decreasing
occurrence:
V pattern ET
V pattern XT
A pattern ET
A pattern XT
Anisometropia at birth is more likely to result in - Ans--Exotropia -
Congenital anisometropia (unequal refractive errors) leads to amblyopia.
The eye that requires the least amount of accommodation for the best vision
is the eye that will be used. There is a general tendency for an amblyopic
eye to drift out (ie, be exotropic), rather than in. (Obviously, this is not always
the case, but it is the most common.)
All of the following are commonly associated with horizontal deviations
except:
a. adult-onset blindness in one eye
