Binocular Vision

Question 1

what are the 3 levels of binocular vision?

Answer 1

-simultaneous perception
-fusion
-stereopsis

Question 2

what is the simultaneous perception of binocular vision?

Answer 2

where both eyes contribute towards visual perception, whether
the images from each eye are combined into a single percept or not.

Question 3

what is the fusion component of binocular vision?

Answer 3

where two images are fused, resulting in a single percept

Question 4

what is stereopsis part of binocular vision

Answer 4

depth of perception of the fusion

Question 5

what are the advantages of binocular vision?

Answer 5

• Increases field of view
• Compensates for physiological blind spot
• Binocular summation
• Stereopsis

Question 6

what are symptoms that may indicate binocular vision problems?

Answer 6

-diplopia
-asthenopic symptoms
-blurred vision
-for young children: rubbing eyes, avoiding certain types of visual tasks e.c.t

Question 7

when may you need to follow up diplopia?

Answer 7

if its monocular as that could indicate more serious pathology

Question 8

what is the smallest prism D you can see with cover test?

Answer 8

2D and that is barely visible

Question 9

how can you measure the size of deviation in cover test?

Answer 9

by doing prism cover test - Keep changing prisms as you do alternating cover tests until you no longer see the eye deviation.

The base goes in the opposite direction of deviation so exophoria needs correction with base IN prism and vice versa

Question 10

why are you less likely to use maddox rod and wing?

Answer 10

-eyes are completely dissociated
-There is a lot of accommodation happening in maddox rod
-Maddox wing is a fixed distance which may not be the patient’s reading distance

Question 11

whats the link between accommodation and convergence?

Answer 11

increased accommodation results in increased convergence

Question 12

what kind of deviation is triggered by uncorrected hyperopia?

Answer 12

eso deviation as Px accommodates more

Question 13

what kind of deviation is triggered by uncorrected myopia

Answer 13

exo deviation as Px accommodates less at near

Question 14

What is fixation disparity?

Answer 14

where there’s a small amount of misalignment of the eyes when they’re being used binocularly after one of them’s been occluded

Question 15

when correcting a deviation, which way does the prism go?

Answer 15

base of the prism goes opposite to the direction of the deviating eye so exo deviation prism is base IN

Question 16

what could each of the following scenarios mean?
-more exo at distance than near?
-more eso at distance than near?
-more exo at near than distance?
-more eso at near than at distance?

Answer 16

• More exo at distance than near = divergence excess?
• More eso distance than near = divergence insufficiency?
• More exo at near than distance = convergence insufficiency?
• More eso at near than distance = convergence excess?

Question 17

what do you record for cover test?

Answer 17

-size
-recovery for phorias
-type of deviation
-laterality for tropias (alternating?)
or
-nmd

Question 18

how does mallet unit to assess fixation disparity work?

Answer 18

when the bottom line moves towards the right eye and the top moves towards the left eye, it is an uncrossed and so eso deviation. If the bottom line moves towards the left and the top line moves towards the right, then its crossed = exo deviation. If the lines are in line with each other and the middle of the X, then no fixation disparity is present

Question 19

What are some of the symptoms involved in asthenopia?

Answer 19

-ocular fatigue
-discomfort
-lacrimation
-headaches

Question 20

what kind of patients should you not use mallet unit on?

Answer 20

-those with va worse than 6/12 in each eye
-suppression / amblyopia

Question 21

which vergence component are you assessing in cover test?

Answer 21

fusional vergence

Question 22

which component of BV is the highest form?

Answer 22

stereopsis

Question 23

what is the contralateral antagonist of the left medial rectus

Answer 23

the right medial rectus

Question 24

what is confusion?

Answer 24

when a patient can see two images superimposed on top of each other making it hard to work out what they’re seeing

Question 25

what is impaired laevoversion?

Answer 25

when movement of both eyes to the left is abnormal

Question 26

what is movement of both eyes to the right called?

Answer 26

dextroversion

Question 27

what does listing’s law suggest?

Answer 27

the eye has a centre of rotation at which it moves

Question 28

what are the 3 axes of fick?

Answer 28

• Y axis is the optical axis - does straight through the pupil = cyclorotation so twists in and out
• X axis lies horizontally = vertical rotation so up and down
• Z axis lies vertically = horizontal rotation so left and right

Question 29

how can you tell in a CT scan if the eyes are dissociated?

Answer 29

If the Y axis are not pointing in the same direction

Question 30

what are the 3 positions of gaze?

Answer 30

-Primary = straight ahead
-Secondary = up/down/left/ right
-tertiary = combo e.g. up and right

Question 31

what does donder’s law suggest?

Answer 31

Ocular orientation required to look at a particular point in space is always the same and independent of the previous ocular position

Question 32

what are agonist and antagonistic muscles?

Answer 32

-Agnostic muscles are eye muscles that work in a pair to move the eyes to look in the same direction
-Antagonistic muscles are muscles that oppose the agonist muscles

Question 33

what is sherrington’s reciprocal law of innervation?

Answer 33

where one muscle of the eyeball contracts so the opposite muscle has to relax

Question 34

what does herring’s law suggest?

Answer 34

contralateral agonists move with equal innervation.

Question 35

what are the two types of binocular movements?

Answer 35

-vergences (oppostive, disjunctive)
-Versions (same direction, conjugate)

Question 36

look at types of versions and vergences screenshot

Answer 36

ok