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AUDE 5260 - Human and Neuroanatomy > Vision and Eye Movements > Flashcards

Vision and Eye Movements Flashcards

1
Q

What is emmetropia?

A

Normal, spherical eye
Distant objects focused on the retina when ciliary muscles are relaxed

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2
Q

What is myopia?

A

Elongated eyeball
Focal plane falls in front of the retina
Near-sightedness

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3
Q

What is hyperopia?

A

Flattened eyeball
Focal point falls behind retina
Far-sightedness

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4
Q

What is keratoconus?

A

When the cornea gradually thins and becomes cone-shaped
Causes impaired vision
Autosomal dominant gene

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5
Q

How is keratoconus treated?

A

Cornea transplant

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6
Q

What is an astigmatism?

A

A type of spherical aberration
The cornea has various radii of curvature

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7
Q

What is presbyopia?

A

Loss of accommodation due to aging

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8
Q

What is diabetic retinopathy?

A

Diabetes leads to small blood vessels
Loss of supply to the eye

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9
Q

What are cataracts?

A

Effects opacity of the eye

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10
Q

What is glaucoma?

A

increases intraocular pressure, excess aqueous humor leads to pressure on the eye

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11
Q

What is scotoma?

A

Blind spot due to legions in the retina
Dancing light in your eye or migraine aura

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12
Q

What is a detached retina?

A

Separation of retina layers
Caused by damage from injury or genetic
Retina floats forward in eye

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13
Q

What is macular degeneration?

A

Age-related disease affecting straight ahead vision

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14
Q

List the 6 extrinsic eye muscles

A

Medial rectus
Lateral rectus
Superior rectus
Inferior rectus
Superior oblique
Inferior oblique

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15
Q

What direction does the superior oblique move the eye?

A

Moves the top of the eye toward the nose

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16
Q

What direction does the inferior oblique move?

A

Moves the top of the eye away from the nose

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17
Q

Why do we have conjugate eye movements?

A

For stable images in both eyes
To avoid double vision
So eyes can track a moving object in a coordinated fashion

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18
Q

Are the visual and vestibular pathways involved in conjugate eye movements?

A

Yes

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19
Q

What is smooth pursuit?

A

Eye tracking
Following a moving object
Used to keep moving target focused on the fovea

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20
Q

If the image moves off of the fovea, does the eye reflexively move to restore the image to its original position during smooth pursuit?

A

Yes

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21
Q

What are saccades?

A

Directing gaze from one target to another

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22
Q

What are the two types of saccades?

A

Intentional saccades - voluntary
Reflexive saccades - when something slams and you reflexively look in that direction

23
Q

How fast is smooth pursuit?

A

5 to 100 degrees per second

24
Q

How fast are saccades?

A

Up to 800 degrees per second

25
Q

What is VOR?

A

Reflexive movement of the eyes in response to vestibular stimulation

26
Q

What kind of movement does VOR produce?

A

Conjugate movement of the same degree and in the opposite direction of the head movement

27
Q

What is nystagmus?

A

Rhythmic oscillation of the eyes

28
Q

What is jerk nystagmus?

A

Fast in one direction, slow in the other

29
Q

What direction does nystagmus happen in?

A

Any direction
Horizonal, vertical, or torsional

30
Q

What is optokinetic nystagmus?

A

Railroad nystagmus
Fixating on passing objects, tracking them until they are out of view, eyes saccade back to the forward position to fixate on new object
Can be tested clinically

31
Q

What is optokinetic nystagmus caused from?

A

Spinning or lesions

32
Q

What is spontaneous nystagmus?

A

Indicated underlying pathology or abnormal condition
Associated with nausea, vertigo, unsteadiness, and falling

33
Q

What is spontaneous nystagmus caused by?

A

Lesions to labyrinth, CN VIII, brainstem, or cerebellum
Lesions may result in an imbalance of neural inputs to the CNS

34
Q

Can vision override spontaneous nystagmus?

A

Yes, in a well-lit room if the CNS is working
Could show up in a vision-denied environment

35
Q

What is vertigo?

A

Sense that the world is spinning or that your head or body is spinning

36
Q

What are the two types of vertigo?

A

Objective - objects/world spinning
Subjective - self spinning

37
Q

What is syncope?

A

Fainting
Partial or complete loss of consciousness
Temporary with recovery

38
Q

What causes syncope?

A

Reduction in blood flow and oxygen to the brain

39
Q

What is presyncope?

A

Light-headedness

40
Q

Can people fixate on a target to stop spontaneous nystagmus?

A

Yes, it allows the visual system to override dizziness

41
Q

What are the motor centers controlling the eyes?

A

Vestibular nuclei, superior colliculus, and accessory oculomotor nuclei (accessory to CN III, IV, and VI)

42
Q

What is the medial vestibulospinal tract used for?

A

Stabilizing the head and neck

43
Q

What is the lateral vestibulospinal tract used for?

A

Stabilizing the body via antigravity muscles

44
Q

What are the superior vestibulospinal tract and medial vestibulospinal tract used for?

A

Hold nuclei of ocular motion, tectal nuclei, and accessory oculomotor nuclei via the MLF

45
Q

Why is the superior colliculus important?

A

Important for directing head movements toward novel stimuli
Does not have direct connections to the nuclei of ocular motion

46
Q

What are the two types of gaze?

A

Horizontal and vertical

47
Q

Are there connections across midline to perform gaze?

A

Yes, because eyes should gaze in the same direction

48
Q

What can disrupt vertical gaze?

A

Pressure or lesions on the rostral brainstem

49
Q

What is a hold signal?

A

A signal following a saccadic movement for the eye to remain in place

50
Q

What happens if the hold signal fails?

A

They eye will drift back to center and anew saccade is initiated to bring the eye back to target

51
Q

What are hold signals mediated by?

A

Medial vestibulospinal tract and cerebellum

52
Q

What would hold signals look like if they failed?

A

Nystagmus
Called gaze-evoked nystagmus or gaze nystagmus

53
Q

What is ophthalmoplegia?

A

Disturbance or weakness of extraocular eye muscles

54
Q

What are the types of ophthalmoplegia?

A

Nuclear - lesion to the nuclei of ocular motion or the associated cranial nerves
Internuclear - lesions involving the MLF
Supranuclear - Lesions involving the cerebral cortex

AUDE 5260 - Human and Neuroanatomy (19 decks)

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