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The Assessment And Management Of Binocular Vision > Introduction > Flashcards

Introduction Flashcards

1
Q

State advantages of having two eyes?

A
  1. Spare eye (insurance )
  2. Increased sensitivity - two eyes/detectors are better than one , better able to detect visual stimuli = summation
  3. Stereopsis - allows us to perceive depth 3D
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2
Q

What is stereopsis ?

A

Ability to combine the images from two eyes - this gives one unified perception of the world

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3
Q

Define ‘ Disparity ‘ .

A

Small hz differences between images in the two eyes that are still fusable

This difference is called disparity .

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4
Q

Define ‘ Fusion ‘

A

Describes the neural processes that bring the retinal images in the two eyes to form/produce a single image.
Fusion occurs to allow BSV.

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5
Q

State some conditions required for fusion to take place .

A

Images must be located on corresponding retinal areas and be relatively similar
Similar in SIZE , BRIGHTNESS, SHARPNESS

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6
Q

What is sensory fusion ?

A

The neural combination of corresponding retinal images into a single Visual percept

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7
Q

What is motor fusion ?

A

The ability to align the eyes in such a manner that sensory fusion can take place
Relies upon the proper functioning of the Intraocular muscles - to pt eye to look at similar object

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8
Q

If you present dissimilar objects to both eyes what can occur ?

A

Suppression
Confusion
Rivalry

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9
Q

Explain what ‘suppression’ is ?

A

Occurs to eliminate one image to prevent confusion

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10
Q

What is ‘ confusion ‘?

A

Leads to one image on top of the other

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11
Q

What is binocular rivalry ?

A
  • When corresponding regions of the two eyes are stimulated by different patterns
  • Stimuli rival in terms of our conscious visual perception and leads to confusion
  • Stimulus seen at given point = DOMINANT
  • Stimulas that can’t be seen = SUPPRESSED
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12
Q

State the relationship between motor and sensory fusion?

A

If motor fusion breaks then sensory can’t take place

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13
Q

Use the whiteboard to show the concept of corresponding retinal points .

A

Retinal location in RE and LE share a common visual direction
Normal

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14
Q

Use the whiteboard to indicate disruption of the visual axis
Give any example.

A

Exotropia - right eye deviating outward
Both objects will compete for visual dominance
Corresponding points = confusion / rivalry
Non corresponding points = Diplopia

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15
Q

Define ‘ Diplopia ‘

A

When non corresponding points are stimulated by the same object this causes diplopia.
This may occur as a result of misalignment of the visual axis

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16
Q

What is another words for Diplopia ?

A

Double vision

17
Q

State the requirements for stereopsis

A

1) Binocular Overlap
2) Partial Decussation
3) Coordinated eye movement

Biological aspects

18
Q

What do we mean by binocular overlap ?

A

Monocular fields overlap

19
Q

What do we mean by partial decussation ?

A

Allows nueral signals from LE and RE to be combined

crossing of nasal fibres

20
Q

What do we mean by coordinated eye movements?

A

Gaze hold and Gaze shift

21
Q

Name the four types of eye movement

A

Saccadic
Pursuit
Vestibular reflexes
Vergences

22
Q

Define saccadic eye movement

A

Quick simultaneous movement of both eyes between 2 or more phases of fixation in same direction

23
Q

Define persuit eye movement

A

Eyes closely following a moving target

24
Q

Define vestibular reflex eye movement

A

Reflex acting to stabilise gaze during head movement with eye movement due to activation of vestibular system

25
Q

Define vergences in relation to eye movement

A

Slow movement of both eyes initiated to track and fuse moving objects located at different distances

26
Q

Use whiteboard to draw the extra ocular muscles in the eye

A

Recti muscles x4

Oblique muscles x2

27
Q

What can go wrong with the binocular vision system ?

A

Misalignment of visual axis

28
Q

When there is a obvious observable misalignment of the visual axis
What is this called ?

A

Manifest deviation

29
Q

When there is a non visible misalignment of the visual axis what is this called ?
Explain …

A

Latent deviation
Can’t observe with naked eye , not visible
Usually involves suspending fusion by covering eye

30
Q

Manifest deviation include …

A

Strabismus
Squint
Heterotropias

31
Q

Latent deviation …

A

Heterophorias

32
Q

Use the whiteboard to draw and name the types of manifest deviations

A

Exotropia
Esotropia
Hypertropia
Hypotropia

33
Q

Name the two hz deviations in manifest deviations

A

Exo and esotropia

34
Q

Name the two vertical manifest deviations

A

Hyper and hypotropia

35
Q

Use the whiteboard to draw and name the latent deviations

A

Esophoria
Exophoria
Hyperphoria
Hypophoria

Have to cover one eye - cover test to reveal presence of deviation

36
Q

What method would you use to detect any ocular deviations ?

A

The cover test

37
Q

Epicanthic fold …

A

Children may look like they have an esotropia but they don’t they just have an epicanthic fold which gives the impression

38
Q

Use the whiteboard to draw the classification system of BV abnormalities

A

Concomitant or incomitant

The Assessment And Management Of Binocular Vision (2 decks)

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