Visual And Ocular Motor Disorders: An Overview

Front 1

Broadly, what are the three parts of the visual pathway?

Back 1

Optical
Retinocortical
Perceptual

Front 2

What is the upper part of the perceptual pathway responsible for?

Back 2

Visuospatial processing

Front 3

What is the lower part of the perceptual pathway responsible for?

Back 3

Recgnition

Front 4

What are some of the clinical manifestations of the retinocortical disorders?

Back 4

Blurred vision
Dim vision
Scotomas
Light spots

Front 5

What is a cause of dim vision?

Back 5

In general, less traffic through the retinocortical system

Front 6

What is a cause of scotoma?

Back 6

Lesion in a part of the retinocortical pathway

Front 7

What is a clinical manifestation of the occiipito-temporal part of the perceptual system?

Back 7

Problems with the what: object, color recognition

Front 8

What is a clinical manifestation of the occiipito-parietal part of the perceptual system?

Back 8

Problems with the where: distributed attention, trouble with spatial relations

Front 9

How do you eliminate optical problems when thinking about optical disorders?

Back 9

Put pinholes!

It gets rid of media problems, refractive errors, etc.

Front 10

What are two things you should always check if you're evaluating what you think is a retinocortical disorder?

Back 10

Pupil reactions

Visual fields

Front 11

What is the pupillary reflex pathway?

Back 11

Front 12

What parts of the midbrain are active in the pupillary reflex pathway?

Back 12

Edinger-westphal nucleus
Branchium of the superior colliculus

Front 13

How do you test for a relative afferent pupil defect? Wht do you find?

Back 13

Swinging light test

If a pupil expands when there's light, you've got one of two problems:
-Defect in that pupil
-Bilateral defect, but the one that expands is worse

Front 14

What test do you use to see where a lesion is in the retinocortical pathway?

Back 14

Visual fields

Front 15

Where are different places on the retinocortical pathway that you can have lesions?

Back 15

1. Retinal ganglion cells, optic nerve

2. Optic chiasm

3. Optic tracts, optic radiations, visual cortex

Front 16

Where are some different places in the optic nerve that you can get defext?

Back 16

Right eye:

1.Fovea/macula
2.Arcurate
3.Radial (YOU SEE THE TEMPORAL FIELD)

Front 17

What part of the vision is lost in a central scotoma? Where does this lesion take place?

Back 17

You get a lesion of all of the fibers from the fovea going into the optic nerve, which leads to a blind spot in the center of vision

Front 18

What part of the vision is lost in a cecocentral scotoma? Where does this lesion take place?

Back 18

Not only in the fovea, but the other ganglia that extend over are effected

It's a scotoma from the blind spot to the point of vision

Front 19

What part of the vision is lost in an arcuate scotoma? Where does this lesion take place?

Back 19

Scimtar with a border along the meridian of sight

Front 20

What part of the vision is lost in a temporal scotoma? Where does this lesion take place?

Back 20

If this is the RIGHT edge, you're losing the NASAL cells, which means that you're having a defect in the TEMPORAL field of sight

Front 21

What happens after the optic chiasm to the visual information?

Back 21

The fibers are segregated into hemifields: "right world" goes to left brain, vice versa

Front 22

If you've got a defect in the optic chiasm, what will be the effect on the visual field?

Back 22

Bitemporal hemianopia: you're losing the sight of the nasal fibers, which are the ones that cross.

This results in an inability to see the TEMPORAL fields

Front 23

If you have a visual field defect in he retrochiasma, what will be the effect on visual fields?

Back 23

Homonymous hemianopia - this could be a defect anywhere past the chiasm

Front 24

How do you want to go about evaluating the perceptual disorders of the visual system?

Back 24

See if they can identify "what" (temporal)

See if they can identify the "where"/spatial (parietal lobe)

Front 25

What are the different types of eye movements performed by the ocular motor system?

Back 25

Saccades
Pursuit
Vergence
Vestibulo-ocular

Front 26

What is the function of a saccade? What is unique about it?

Back 26

Move the eyes from one equidistant target to another

You don't see anything between the two points!

Front 27

What is the function of a pursuit?

Back 27

Keep the eyes on a target when the target moves

Front 28

What is the function of a vergence?

Back 28

Keep the eyes on a target as the distance from the viewer changes

Front 29

What is the function of a vestibulo-ocular eye movements?

Back 29

Keep the eyes on the target when the viewer's head moves

Front 30

What are the two types of saccades?

Back 30

Voluntary
Invountary

Front 31

What are some of the voluntary saccades?

Back 31

Move the eyes to a target seen in a peripheral field

Move the eyes to an unseen target

Front 32

What are some of the involuntary saccades/

Back 32

REM

Fast phases of nystagmus

Random

Front 33

In general, where does the control of involuntary horizontal saccades take place?

Back 33

Front of the brain

Front 34

In general, where does the control of voluntary horizontal saccades take place?

Back 34

Back of the brain

Front 35

What is the signalling pathway for the control of horizontal saccades?

Back 35

1. Signal comes in from PPRF
2. Synapse in the CNVInucleus
3.2 signals sent out:
-Lateral rectus
-Interneuron to the CNIII nucleus through the MLF

Moving the eyes

SIgnalling is ipsilateral once you get to hte pons

Front 36

In general, how are vertical saccades controlled?

Back 36

Bihemispheric

One group of pathways for upgaze, another for downgaze

Front 37

What pathways are involved in the control of vertical saccades?

Back 37

Front 38

What are some of the different disorders of saccade?

Back 38

Absent (gaze palsy)
Reduced amplitude (hypometric)
Slow
Inaccurate (dysmetric)
Intrusive

Front 39

Where is pursuit generated in the brain?

Back 39

Occipito-parietal region

Front 40

In order to perform pursuit eye movements, what is a precondition?

Back 40

You've got to be able to see first!

Front 41

What are the pathways involved in the control of horizontal pursuit?

Back 41

The posterior part of the brain dominates

The final common pathway is the CNVI nucleus

Cerebellum is also involved.

Front 42

How do you evaluate pursuit?

Back 42

Have the patient follow your moving light/finger

Is it smooth?
Is it complete?
Are there oscillations?

Front 43

If a patient is unable to pursue, what will you see?

Back 43

They'll be able to follow your finger for a while, stop, and then have to perform a catchup saccade

Front 44

What are various causes of problems with pursuit?

Back 44

Lack of sleep
Alcohol intoxication

Pursuit is quick to go, as far as eye movements go

Front 45

What are some of the disorders of pursuit?

Back 45

Cogwheel
Absent

Front 46

What are the two types of vergent eye movements?

Back 46

Convergence: move the eyes closer to one another

Divergence (hard to do): move the eyes farther apart from one another

Front 47

Generally, what are the parts of the brain involved in the vergence pathway?

Back 47

Generation in the parieto-occipital regions

Signal travels to the midbrain

We don't know, exactly

Front 48

How do you go about evaluating vergence?

Back 48

Measure ocular alignment when the eyes are focusing on a distant target, then when they're focusing on a near target

Front 49

What are the different disorders of vergent?

Back 49

Too much convergence

Too little convergence

Front 50

Where is the vestibulo-ocular reflex generated?

Back 50

Labyrinths

Front 51

Does the vestibulo-ocular reflex reach the cerebrum?

Back 51

No.

Front 52

What parts of the brain are involved in the control of the vestibulo-ocular reflex?

Back 52

Front 53

How do you evaluate the vestibulo-ocular reflex?

Back 53

It's hard: if people are awake, they make voluntary eye movements

1. Doll's headmaneuver; move head rapidly, look for slow contraversive conjugate eye movements
2. Cold water calorics: look for ipsiversive slow conjugate eye movements and perhaps contraversive involuntary saccades

Front 54

What are some of the vestibulo-ocular disorders?

Back 54

If the entire thing is underfunctioning, the entire world looks like it's a hand-held camera: "oscillopsia"

Unilateral: nystagmus

Front 55

What are the features of a supranuclear gaze palsy?

Back 55

1. Absent voluntary gaze

2. Intact vestibulo-ocular reflex

Front 56

What are some of the different levels of the visual field pathways?

Back 56

Supranuclear: brain cerebral centers to the PPRF

Intranuclear: MLF

Nuclear: PPRF, pons