Vision and Eye Movements

Question 1

What is emmetropia?

Answer 1

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

Question 2

What is myopia?

Answer 2

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

Question 3

What is hyperopia?

Answer 3

Flattened eyeball
Focal point falls behind retina
Far-sightedness

Question 4

What is keratoconus?

Answer 4

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

Question 5

How is keratoconus treated?

Answer 5

Cornea transplant

Question 6

What is an astigmatism?

Answer 6

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

Question 7

What is presbyopia?

Answer 7

Loss of accommodation due to aging

Question 8

What is diabetic retinopathy?

Answer 8

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

Question 9

What are cataracts?

Answer 9

Effects opacity of the eye

Question 10

What is glaucoma?

Answer 10

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

Question 11

What is scotoma?

Answer 11

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

Question 12

What is a detached retina?

Answer 12

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

Question 13

What is macular degeneration?

Answer 13

Age-related disease affecting straight ahead vision

Question 14

List the 6 extrinsic eye muscles

Answer 14

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

Question 15

What direction does the superior oblique move the eye?

Answer 15

Moves the top of the eye toward the nose

Question 16

What direction does the inferior oblique move?

Answer 16

Moves the top of the eye away from the nose

Question 17

Why do we have conjugate eye movements?

Answer 17

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

Question 18

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

Answer 18

Yes

Question 19

What is smooth pursuit?

Answer 19

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

Question 20

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

Answer 20

Yes

Question 21

What are saccades?

Answer 21

Directing gaze from one target to another

Question 22

What are the two types of saccades?

Answer 22

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

Question 23

How fast is smooth pursuit?

Answer 23

5 to 100 degrees per second

Question 24

How fast are saccades?

Answer 24

Up to 800 degrees per second

Question 25

What is VOR?

Answer 25

Reflexive movement of the eyes in response to vestibular stimulation

Question 26

What kind of movement does VOR produce?

Answer 26

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

Question 27

What is nystagmus?

Answer 27

Rhythmic oscillation of the eyes

Question 28

What is jerk nystagmus?

Answer 28

Fast in one direction, slow in the other

Question 29

What direction does nystagmus happen in?

Answer 29

Any direction Horizonal, vertical, or torsional

Question 30

What is optokinetic nystagmus?

Answer 30

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

Question 31

What is optokinetic nystagmus caused from?

Answer 31

Spinning or lesions

Question 32

What is spontaneous nystagmus?

Answer 32

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

Question 33

What is spontaneous nystagmus caused by?

Answer 33

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

Question 34

Can vision override spontaneous nystagmus?

Answer 34

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

Question 35

What is vertigo?

Answer 35

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

Question 36

What are the two types of vertigo?

Answer 36

Objective - objects/world spinning Subjective - self spinning

Question 37

What is syncope?

Answer 37

Fainting Partial or complete loss of consciousness Temporary with recovery

Question 38

What causes syncope?

Answer 38

Reduction in blood flow and oxygen to the brain

Question 39

What is presyncope?

Answer 39

Light-headedness

Question 40

Can people fixate on a target to stop spontaneous nystagmus?

Answer 40

Yes, it allows the visual system to override dizziness

Question 41

What are the motor centers controlling the eyes?

Answer 41

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

Question 42

What is the medial vestibulospinal tract used for?

Answer 42

Stabilizing the head and neck

Question 43

What is the lateral vestibulospinal tract used for?

Answer 43

Stabilizing the body via antigravity muscles

Question 44

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

Answer 44

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

Question 45

Why is the superior colliculus important?

Answer 45

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

Question 46

What are the two types of gaze?

Answer 46

Horizontal and vertical

Question 47

Are there connections across midline to perform gaze?

Answer 47

Yes, because eyes should gaze in the same direction

Question 48

What can disrupt vertical gaze?

Answer 48

Pressure or lesions on the rostral brainstem

Question 49

What is a hold signal?

Answer 49

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

Question 50

What happens if the hold signal fails?

Answer 50

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

Question 51

What are hold signals mediated by?

Answer 51

Medial vestibulospinal tract and cerebellum

Question 52

What would hold signals look like if they failed?

Answer 52

Nystagmus Called gaze-evoked nystagmus or gaze nystagmus

Question 53

What is ophthalmoplegia?

Answer 53

Disturbance or weakness of extraocular eye muscles

Question 54

What are the types of ophthalmoplegia?

Answer 54

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