Week 7

Question 1

What are the 2 stimuli to cause vergence?

Answer 1

1. Disparity

2. Retinal Blur

Question 2

Fusional vergence reduces retinal disparity to a minimum using what type of feedback system?

Answer 2

Negative Visual Feedback

Question 3

Accommodative vergence has no direct effect on retinal blur stimulus using what type of feedback system?

Answer 3

Open-loop

Question 4

After accommodative vergence, what vergence will correctly align the eyes?

Answer 4

Fusional vergence

Question 5

How many msec for the accommodative vergence signal to blur?

Answer 5

200msec

Question 6

How many msec for a disparity stimulus?

Answer 6

180msec

Question 7

Vergence and accommodation are sped up when it occurs in association with ____?

Answer 7

Saccades

Question 8

What eye movement is apart of a strategy to facilitary disparity-driven vergence?

Answer 8

Blinks - slow down convergence, divergence and saccades

Question 9

What neurons must be inhibited to allow for vergence to occur?

Answer 9

Omnipause neurons

Question 10

If someone cannot converge or diverge, what part of the brainstem are we concerned about?

Answer 10

Midbrain

Question 11

An important component of the neural substrate for rapid vergence-saccade movements is the ____?

Answer 11

PPRF

Question 12

The PPRF house pre-motor burst neurons that are important for ?

Answer 12

horizontal saccades (receives signal for vergence)

Question 13

What is essential for optimal visuo-motor function?

Answer 13

Adaptive capability

Question 14

If a prism is placed in front of an eye, then the phoria is changed by______. How long will this need to be sustained?

Answer 14

• will change by amount of prism (called phoria adaptation)

- must hold vergence for 30 secs

Question 15

A robust phoria adaptation mechanism might limit the efficacy of prism tx. This is called ?

Answer 15

Eating prism - phoria adaptation mechanism overcomes effect of prism

Question 16

Prism is not a good mechanism for tx of ___ ____?

Answer 16

Convergence insufficiency

Question 17

Prism and Vergence adaptation cause what 2 things?

Answer 17

1. Reduction in FD

2. Change in phoria toward direction of stimulus (if exo, now eso)

Question 18

In response to binocular disparity, what type of fusional vergence is stimulated?

Answer 18

Fast fusional vergence (stressful on vergence system)

Question 19

To overcome the stress, a ___ fusional vergence is evoked. This is called what?

Answer 19

Slow fusional vergence

- called prism adaptation

Question 20

Prism adaptation converts what ?

Answer 20

Converts FFV to SFV

Question 21

What is used as a feedback mechanism to change from fast reflex accom. to slow reflex accomm.?

Answer 21

Blur

Question 22

What is used as a feedback mechanism to change from FFV to SFV?

Answer 22

Fixation disparity

Question 23

CA/C sends info from the vergence system to the ____ system.

Answer 23

accommodative

Question 24

AC/A sends info from accommodative system to ____ system?

Answer 24

vergence

Question 25

What converts the fast reflex accom. to the slow reflex accom.?

Answer 25

Accom. Amplitude

Question 26

Accommodation and vergence change in unision via the cross-link interaction between?

Answer 26

CA/C and AC/A

Question 27

BD: High AC/A with?

Answer 27

Low accommodative Response

Question 28

BD: Low AC/A with?

Answer 28

High accommodative response

Question 29

BD: High CA/C with?

Answer 29

Low PA

Question 30

BD: Low CA/C with?

Answer 30

High PA

Question 31

What are the 2 ways to manage binocular disorders?

Answer 31

Passive and Active

Question 32

What ways can we passively manage BDs?

Answer 32

Prisms and Lenses | - to relieve stress of system

Question 33

What ways can we actively manage BDs?

Answer 33

Vision therapy

Question 34

What are the 3 neural components needed to cause vergence eye movements?

Answer 34

1. Cerebral Cortex 2. Brainstem vergence generator 3. Ocular motor neurons

Question 35

Where is the brainstem vergence generator located?

Answer 35

Mesencephalic reticular formation

Question 36

What type of cells are in the brainstem vergence generator? Which cell is found more abundantly?

Answer 36

Premotor convergence and divergence cells | - more convergence neurons

Question 37

What 4 cortical areas are in the cerebral cortex?

Answer 37

1. Frontal Cortex 2. Parietal Cortex 3. MT 4. MST

Question 38

What cells are involved in the cerebral cortex vergence decision?

Answer 38

1. Near cells 2. Far cells 3. Size coding cells

Question 39

Vergence tonic cells carry what signal?

Answer 39

step/position signal

Question 40

Vergence burst cells carry what signal?

Answer 40

pulse/velocity signal

Question 41

Vergence burst-tonic cells carry what signal?

Answer 41

both step & pulse signals

Question 42

An acute lesion in a human's cerebellum causes ?

Answer 42

convergence weakness

Question 43

Acute ablation in a monkey's cerebellum causes what?

Answer 43

transient paralysis of vergence

Question 44

Jump/Saccadic Vergence refers to ? What test can we use to determine this?

Answer 44

- refers to quick changes and maintenance of vergence angle | - Vergence Facility testing (12BD, 3BI)

Question 45

Smooth/Pursuit Vergence refers to what?

Answer 45

slow changes in vergence angle due to smooth tracking of target

Question 46

Anisometropic correction is best using spectacles or CLs?

Answer 46

CLs