Binocular Vision: Lecture 10: Horopter 2

Question 1

1. Stimulus in Physical Space, images on the fovea of each eye is seen as what?
2. A stimulus Not Imaged on Corresponding retinal points should produce what?
3. The Surface in Visual Space perceived by stimulation of corresponding points is called what?

Answer 1

1. as a SINGLE PERCEPT in Visual Space
2. a Double Image in Visual Space
3. The GEOMETRIC HOROPTER

Question 2

Vieth-Muller Circle

1. All points along the circumference of the V-M Circle Subtend Equal Angles in what eyes?
   a. Thus, Because of this geometry, Targets HAVE to be placed on the V-M Circle in order to be IMAGED on what?
   b. V-M Circle is KNOWN as that?

Answer 2

1. Right and Left Eyes (so Theta L = Theta R)
   a. on Corresponding Points
   b. as the Geometric or Theoretical “Horopter” (The points in space that are imaged onto Corresponding Points)

Question 3

The Shape of the Empirical Horopter and its Analysis

1. The Vieth-Muller Circle is DEFINED by what 3 Points?

Answer 3

1. the FIXATION POINT and the ENTRANCE PUPILS of the EYES

Question 4

1. The V-M Circle (Geometric Horopter) is, therefore, the LOCI of what?
2. The Value R represents what?
   a. What’s the equation?

Answer 4

1. of all Corresponding Retinal Points as influenced by the OPTICS of the EYE
2. The RATIO of the TANGENTS of the 2 EXTERNAL LONGITUDINAL Angles at ANY POINT on the HOROPTER
   a. R = tan(aplha2)/tan(alpha1)

Question 5

V-M Circle

1. R = what?
   a. What does R = 1 signify?
2. When R > 1, Angle a2 is greater/less than Angle a1 in PHYSICAL SPACE?
   a. What does this mean?
3. When R

Answer 5

1. Relative Magnification of the Retinal Images b/w the 2 Eyes
   a. that the LEFT and RIGHT Eye Magnifications are EQUAL in the 2 EYES
2. a2 EXCEEDS Angle a1.
   a. Right eye’s image is MAGNIFIED relative to that of the Left eye
3. a1 is the GREATER ANGLE
   a. Signifying that the Left Eye’s Image is Relatively Magnified

Question 6

1. They analytical Plot is based off the Following Equation: R = ?
   a. Slope H is determined by what?
   b. What is Ro?
   c. By plotting the Value of R for each data point on the HOROPTER as a function of the Magnitude of the Angle a2, we obtain what is called what?
2. So the Analytical Plot is…
   a. What does the Y-intercept mean?

Answer 6

1. H(tan(a2)) + Ro
   a. by the Degree of Curvature of the Horopter
   b. the Value of Tangent Ratio R measured at the fixation point. It’s also an Index of ANISEKONIC Index
   c. the ANALYTICAL PLOT!
2. R vs. a2 (for each point on the Horopter)
   a. Ro determined by the slope of the Horopter at the Fixation Point

Question 7

Analytical Plot (2)

1. The Ratio of the Magnification of the Image Size in 1 Eye relative to that of the Image in the other eye is what?
   a. This relative magnification results in what?
2. When Ro = 1, what does that mean?
3. When Ro DOES NOT EQUAL 1, what does that tell us?

Answer 7

1. Ro
   a. In TILTING or SKEWING of the Horopter, Relative to the FRONTAL PLANE
2. There’s NO SKEWING of the HOROPTER; It has a FLAT SLOPE AT the FIXATION POINT
3. There’s a Uniform Relative Magnification (equal Magnification at EVERY RETINAL LOCATION) of one eye’s image across the visual field, Tilting the Horopter and One’s Percept of the World.

Question 8

Analytical Plot (3)

1. When Ro > 1, which eye’s image is LARGER, and what does the Horopter do?
2. When Ro

Answer 8

1. the LEFT eye’s image. Horopter is rotated TOWARD the EYE.
2. the Right Eye’s image is LARGER, and the Horopter SKEWS toward the RIGHT EYE
3. M = (Ro - 1) x 100

Question 9

1. Histological Studies show that the Photoreceptors are MORE DENSELY PACKED in which part of the RETINA? (Nasal or Temporal)
2. What could also make the Horopter DEVIATE from the V-M Circle?
3. A Fronto-parallel Plane appears to be tilted nearer/away from the Eye with GREATER MAGNIFICATION?
   a. What will the subject have to do with the RODS to MATCH the Apparent Fronto-parallel Plane?
4. What if the HOROPTER is TILTED?

Answer 9

1. More Dense Nasally than Temporally!
2. An ASYMMETRIC MAPPING from RETINA to the CORTEX in the 2 eyes.
3. AWAY
   a. They will have to MOVE the RODS CLOSER to MATCH the apparent Fronto-parallel Plane
4. it indicates GREATER RETINAL MAGNIFICATION on the SIDE TILTED CLOSER to the eye.

Question 10

1. The local signs in the Nasal Retina are spaced closer together or further apart?
   a. This is called what?
2. The ECCENTRICITY of a given point in the Nasal Retina is More/Less than that of its Corresponding Point in the Temporal Retina of the Other eye?

Answer 10

1. CLOSER TOGETHER than those of the Temporal Retina
   a. NASAL PACKING!
2. LESS.

Question 11

The Empirical (Longitudinal) Horopter

1. When doing an experiment on someone, we find that the locations in space that have IDENTICAL MONOCULAR VISUAL DIRECTIONS that are imaged onto CORRESPONDING POINTS are in the same/Different as the V-M Circle?
   a. The Empirical Longitudinal Horopter is usually More/Less CONCAVE than the V-M circle?

Answer 11

1. Corresponding points are NOT THE SAME as the V-M Circle

a. LESS CONCAVE

Question 12

Hering-Hillebrand Horopter Deviation

1. What does the VALUE of H Tell us?
2. When the Measured horopter LIES ON THE V-M CIRCLE, H is EQUAL to what?
3. What about when the HOROPTER is LESS CURVED than the V-M Circle?
4. And when the Horopter is MORE CURVED than the V-M Circle?

Answer 12

1. the Relative Curvature of the Horopter
2. ZERO!
3. H is POSITIVE
4. H is NEGATIVE!

Question 13

Hering-Hillebrand Horopter Deviation (2)

1. What is the Typical VALUE of H?
   a. What does this indicate about the Horopter compared to the V-M Circle?
2. H is a measure of what?
   a. Which tells us what about MAGNIFICATION?
3. The Corresponding Points are or are Not laid out in an evenly spaced distribution b/w the two eyes?

Answer 13

1. +0.1 to +0.2
   a. that the Horopter is usually FLATTER
2. of Nonuniform Relative Magnification across the VF.
   a. i.e., how MAGNIFICATION CHANGES ACROSS the VF because of a deviation of the horopter from an exact Geometric (Angular) Layout)
3. NOT LAID OUT.

Question 14

1. The V-M Circle (VMC) is based on the assumption that there is what?
2. This is not the case tho. Which receptors are SPACED FURTHER APART: Temporal Retinal or Nasal Retinal Receptors?
3. Temporal corresponding points of one eye and the nasal corresponding points of the other eye are located at the SAME/DIFFERENT Angular subtenses from the Common Visual Direction?
4. This produces a what b/w the Actual Location of an Object and its Perceived Location?

Answer 14

1. A Uniform distribution of Light Receptor Cells in EACH RETINA
2. Temporal Retinal Receptors
3. DIFFERENT
4. Produces a MISMATCH.

Question 15

1. What is it: The Viewing distance at which the Apparent and Objective Frontal Planes COINCIDE: which means that the HOROPTER TRULY IS FLAT?
   a. What is the Equation for this?
2. The Abathic Distance is USUALLY about how FAR from the OBSERVER?
3. What also changes proportionately with INCREASED FIXATION DISTANCE?
4. What happens to the Hering-Hillebrand Deviation (H) with varying FIXATION DISTANCES?

Answer 15

1. the ABATHIC DISTANCE
   a. H = 2a/b

2a = Interpupillary distance

b = Fixation distance

2. about 1-2 METERS! (KNOW!)
3. the Curvature of the V-M Circle
4. IT REMAINS THE SAME!

Question 16

1. The ABSOLUTE Curvature of the Horopter and the V-M Circle change with Viewing distance. However, what DOES NOT CHANGE b/w them?
   a. What value represents this?
   b. This constancy across viewing distances means what?

Answer 16

1. The DIFFERENCE in curvature of the horopter, relative to the V-M circle
   a. The slope: H.
   b. that the Layout of Corresponding Points in the 2 Retinas REMAINS CONSTANT with CHANGES in VERGENCE!

Question 17

1. At Nearpoint Fixation Distances, what is a Straight line parallel to the Head and intersecting the V-M Circle AT THE FIXATION POINT?
   a. When Measured Empirically, what TILTS AWAY from the TRUE VERTICAL?
   b. What causes this tilt?

Answer 17

1. the THEORETICAL VERTICAL HOROPTER
   a. the VERTICAL HOROPTER tilts away from the true vertical
   b. RELATIVE EXCYCLOTORSION of the Vertical Meridians of the RETINAS

Question 18

The Horopter in Abnormal Binocular Vision

1. In constant Strabismic Pts, what happens to the Horopter?
2. The Horopters of ESOTROPES DO NOT FOLLOW what?
   a. Instead, what is found in the Horopter NEAR THE FIXATION POINT?!
3. A Regional Spatial Distortion under binocular Conditions may be a result of WHAT?!

Answer 18

1. it will be SHIFTED TOWARD the intersection of their visual AXES
2. the Smooth curve typical of normal subjects
   a. a LARGE NOTCH (Flom Notch?)
3. of ANOMALOUS CORRESPONDENCE

Question 19

Horror Fusionis

1. Adult Patients w/a History of Early-Onset Strabismus, ESP. ESOTROPIA, can demonstrate a CONDITION CALLED…?
   a. In this condition, the Pt may be thought of as having what?
2. What is HORROR FUSIONIS ASSOCIATED with?
3. Sudden Motion seen near the point of SUPERIMPOSITION simply reflects the target of the DEVIATING EYE doing what?

Answer 19

1. HORROR FUSIONIS (basically an AVOIDANCE of FUSION by the Patient)
   a. as having NO CORRESPONDING POINTS, or corresponding points that shift or recalibrate in real time.
2. ANOMALOUS CORRESPONDENCE!
3. crossing the rapidly changing portion of the Horopter Notch

Question 20

Aniseikonia

1. Affects what % of the POPULATION (KNOW…)?
   a. What is it?
2. Optical Aniseikonia is caused by a Difference in what/
   a. This may be caused by 2 things?

Answer 20

1. 2-3%
   a. Difference in Magnification b/w the 2 eyes.
2. in Retinal Image size b/w the 2 eyes
   a. AXIAL ANISOMETROPIA (Axial Aniseikonia) or REFRACTIVE ANISOMETROPIA (refractive aniseikonia)

Question 21

1. This is a Form of Optical Aniseikonia SPECIFICALLY Caused by External Optical Factors like what?
2. What is this: a Small-Magnitude Nonoptical Aniseikonia that can occur even in EMMETROPES, in which the 2 Retinal Images are Physically Equal in SIZE, YET are still perceived to be different in size?

Answer 21

1. INDUCED ANISEIKONIA; like an AFOCAL MAGNIFIER: SIZE LENS

2. NEURAL or ESSENTIAL Aniseikonia

Question 22

1. What is a Size lens?
2. What do Size lenses do?
3. A Size lens with Magnification in ONLY 1 Meridian is CALLED what?
   a. Magnificaiton in ONE MERIDIAN causes what?

Answer 22

1. THICK LENS w/Parallel Front and Back Surfaces that Changes the Magnification of an Image w/o having any dioptric Power
2. Magnify the ENTIRE IMAGE (overall magnifier) if their Front and Back Surfaces are SPHERICAL!
3. Meridional Size Lens
   a. causes Shape Changes in VIEWED Objects

Question 23

1. What is the Power Factor?
   a. Eqn? Mp = ?
   b. What does h refer to?
   c. What does Fv refer to?

Answer 23

1. the Magnification Induced by the Refractive Power of the Lens
   a. Mp = (1)/(1-hFv)
   b. Vertex distance
   c. Back Vertex Power of the Lens

Question 24

1. What is the Shape Factor?
   a. Eqn: Ms = ?
   b. t =?
   c. F1 = ?

Answer 24

1. Magnification INDUCED by the THICKNESS and BASE CURVE of the Lens, INDEPENDENT of ITS POWER
   a. Ms = (1)/(1-(t/n’)*F1)
   b. t = Lens thickness, n’ = Index of Refraction
   c. Front Surface Power