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III. Binocular Vision > Binocular Vision and Disparity (M2) > Flashcards

Binocular Vision and Disparity (M2) Flashcards

1
Q

If the patient is a right esotrope and they are attempting to fixate on an object straight ahead (and can with the left eye), what type of diplopia are they experiencing?

A

uncrossed diplopia

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2
Q

Is stereothreshold usually larger (poorer) or smaller (better) than vernier acuity threshold?

A

larger (worse)

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3
Q

What is the circle that includes the fixation point and the two entrance pupils where objects have equal oculocentric angles? 1. What is the retinal disparity of these points? 2

A
  1. Vieth-Muller Circle

2. 0

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4
Q

What is the relative depth (Δd) corresponding to a particular disparity (η)?

A

the stereoscopic depth interval

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5
Q

What is the equation used to calculate the relative disparity for a Wheatstone stereoscope?

A

η(rad) = - (X(L) - X(R))/(dist from eyes)

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6
Q

What is the first stereoscope that used mirrors?

A

Wheatstone mirror stereoscope

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7
Q

What is the optical device to effectively increase the PD in the measurement of disparity? 1. What does this do and what is it used for? 2

A
  1. telestereoscope

2. decreases stereoscopic depth interval to help tell if hitting targets far away (in war)

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8
Q

What is the image presentation of separate targets presented one to each eye called (not real world objects)? 1. What are examples of this in clinic? 2

A
  1. dichoptic stimulation

2. Stereoscope, anaglyph, polaroid, alternating shutters

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9
Q

When looking at cards with a black background and red lettering, what color lens would be able to see the lettering? 1. What color lens wouldn’t be able to see it? 2

A
  1. red lens

2. green lens

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10
Q

How does fixating in front or behind an object impact the stereothreshold? 1. What can this help to find clinically? 2

A
  1. raises threshold

2. reveal micro-strabismus

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11
Q

How close does an object have to be to determine stereoscopically that it is closer than a star?

A

d = 825m = 2,707 ft

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12
Q

What area on the retina has the lowest stereothreshold?

A

foveal region

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13
Q

What is the equation to calculate the relative disparity for dichoptic stimulation?

A

η(rad) = (X(L) - X(R))/d

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14
Q

What is the critical retinal disparity for double vision called?

A

diplopia threshold

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15
Q

What is an area in the retina of one eye, which when stimulated simultaneously with a point in the retina of the other eye provides single binocular vision? 1. What does this allow for? 2

A
  1. Panum’s area

2. fusion of small disparities so single vision on Randot even with disparity present

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16
Q

What does the sign indicate for relative disparity?

A

relative depth

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17
Q

What is the cortical mechanism in which images from two eyes are integrated into single perceptual whole?

A

sensory fusion

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18
Q

During the Hess Lancaster Screen with a white screen and a red light shone on the screen, what color glasses (R or G) is able to see the light? 1. Not able? 2

A
  1. red lens

2. green lens

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19
Q

Is an object outside the Vieth-Muller circle positive or negative in value?

A

negative (uncrossed)

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20
Q

What is the equation used to calculate the relative disparity for a Brewster stereoscope?

A

η(rad) = (X(L) - X(R))/(dist from lens)

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21
Q

What is the difference in the angles of binocular parallax called? 1. What is the equation? 2

A
  1. relative disparity

2. γ(1) - γ(2) = φ(L) - φ(R)

22
Q

What is the stimulus to stereopsis? 1. When does it mature? 2

A
  1. LATERAL disparity

2. 4 months

23
Q

What is the difference in absolute (retinal) disparity between two objects called (with symbol)?

A

relative disparity (η or eta)

24
Q

What are important factors in determining the stereothreshold?

A
  1. target type/size
  2. length of vertical lines (better for longer lines)
  3. luminance of targets (better for more luminance)
  4. Exposure duration of targets (more time means better threshold)
25
Q

What is the minimum relative disparity required for stereopsis called?

A

stereothreshold

26
Q

What is the average stereothreshold for the Howard-Dolman?

A

15”

27
Q

What is the alternating shutters/images device that is able to achieve dichoptic presentation?

A

synchronous shutter stereoscope

28
Q

What is the equation to calculate the relative disparity for dioptic stimulation?

A

η = (β(1L) - β(1R)) - (β(2L) - β(2R))
η = φ(L) - φ(R)
** η(rad) = PDΔd/d^2* know this one

29
Q

What is the movement that adjusts eye position so object of regard is imaged on both foveas?

A

motor fusion

30
Q

What position is unimportant in terms of relative disparity?

A

fixation position

31
Q

Is an object inside the Vieth-Muller circle positive or negative in value?

A

positive (crossed)

32
Q

What is normal diplopia resulting from retinal disparity called?

A

physiological diplopia

33
Q

What is the image presentation of a target seen simultaneously by both eyes called? 1. What are examples of this in clinic? 2

A
  1. dioptic stimulation

2. standard VA charts, near point cards, etc

34
Q

Which type of fusion is not required for stereopsis?

A

sensory fusion

35
Q

Does monocular or binocular blur increase (worsen) the stereothreshold more?

A

monocular

36
Q

When looking at cards with a white background and red lettering, what color lens would be able to see the lettering? 1. What color lens wouldn’t be able to see it? 2

A
  1. green lens

2. red lens

37
Q

What are the clinical methods to find the stereothreshold?

A
  1. Howard-Dolman Apparatus
  2. Verhoeff Stereopter
  3. Brewster stereoscope
  4. Orthoscope
38
Q

What is the disparity range that permits stereopsis called?

A

the region of depth

39
Q

What type of stereopsis is where the depth sensation is linearly proportional to disparity?

A

fine stereopsis

40
Q

What type of stereopsis is where the depth sensation has a non-monotonic relationship to disparity?

A

coarse stereopsis

41
Q

What is present over most of the region of depth?

A

physiological diplopia

42
Q

What type of target is the Worth’s first degree? 1. Second degree? 2. Third degree? 3

A
  1. non-identical targets (non-fusible)
  2. identical targets (fusible)
  3. contain stereo (disparity) features
43
Q

What is a common (30% of pop) deficiency of stereopsis that is limited to crossed or uncrossed disparity called? 1. What type of stereopsis is altered? 2

A
  1. stereoanomaly

2. coarse stereopsis

44
Q

What are the six classes of cortical disparity detectors?

A
  1. far
  2. near
  3. tuned zero
  4. tuned inhibitory
  5. tuned far
  6. tuned near
45
Q

Is fine stereopsis a transient or sustained response? 1. Parvocellular or magnocellular units? 2. More or less defects in population than coarse? 3

A
  1. sustained
  2. parvocellular
  3. less
46
Q

Is coarse stereopsis a transient or sustained response? 1. Parvocellular or magnocellular units? 2. More or less defects in population than fine? 3

A
  1. transient
  2. magnocellular
  3. more
47
Q

What is the stereopsis called when relative disparity is processed independently for each local target pair? 1. What is an example of this? 2

A
  1. local stereopsis

2. simple line targets

48
Q

What is the stereopsis called when relative disparities are processed interactively over a large region of the binocular field? 1. What is an example of this? 2

A
  1. global stereopsis

2. Random dot stereogram or highly structured environments

49
Q

What is the significance of random dot stereograms?

A
  1. stereopsis does not require monocularly identifiable contours
  2. RDS is useful in detecting the presence of stereopsis
50
Q

What can stereopsis be useful in revealing?

A

camouflage

III. Binocular Vision (15 decks)

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