Exam 2 Review Flashcards
What is the unique direction associated with each retinal image location?
Oculocentric visual direction
What is oculocentric visual direction also known as?
Local sign
What is the perceived direction of an object relative to the body?
Cyclopean direction
What is another phrase for cyclopean direction?
Egocentric direction
What 2 elements contribute to the perception of egocentric direction?
- Oculocentric direction
2. Direction of gaze
What 2 elements contribute to complete egocentric localization?
- Egocentric direction
2. Distance (from stereopsis)
What do corresponding points share?
Visual direction
What is the locus of all points in space that image on corresponding retinal points?
Horopter
What criterion does the IVD horopter use?
Identical visual direction
What horopter is considered the “purest” way to measure the empirical horopter?
IVD horopter
What type of task does the IVD horopter rely on?
Vernier task
Where do the locus of points for the AFPP horopter appear in relation to the fixation target?
At the same stereoscopic distance
Parallel to the face like a picket fence
What does AFPP stand for?
Apparent
Fronto
Parallel
Plane
What is fixation disparity?
Convergence error relative to fixation
Regarding over-convergence and under-convergence, what would eso and exo deviations be?
Over-convergence: eso deviation
Under-convergence: exo deviation
What is located at the center of Panum’s fusional space?
Singleness horopter
At what location are stereoacuity thresholds at their lowest?
Minimum stereoacuity threshold horopter
Through what 2 points of each eye does the Veith-Muller circle run?
- Fixation point
2. Nodal point
What is a major assumption of the Veith-Muller circle?
Corresponding retinal points are distributed symmetrically
What is a major reason for the difference between the theoretical and empirical horopter?
Differences in arrangement of corresponding retinal elements
What is the angular deviation between the empirical horopter and the Veith-Muller circle known as?
Hering-Hillebrand deviation
Also known as the H deviation
How does the empirical horopter change relative to the observer as fixation distance increases?
Horopter becomes more convex relative to the observer as fixation distance increases
What is abathic distance?
Viewing distance at which the shape of the horopter is flat
What planes are coincident at the abathic distance?
- Objective plane
2. Apparent frontal plane
What 2 points is the external longitudinal angle formed by?
- Fixation point
2. Secondary Point
When R is not equal to 1, what will the empirical horopter exhibit?
Tilt
Towards one of the two eyes
The analytical plot graphs the R-coefficient as a function of what?
Tangent of alpha-2
The slope of the analytical plot is given by what value?
H-coefficient
If H is not equal to 0, how does the empirical horopter appear relative to the Veith-Muller circle?
Either flatter or steeper in curvature
What is aniseikonia?
Difference in size and/or shape of two retinal images
What is anisometropia?
Difference in refractive error between the two eyes
What is the most common cause of aniseikonia?
Anisometropia
What is anisophoria?
Phoria that varies in different positions of gaze
What would a meridional size lens of axis 90 do to an image?
Magnify image in the horizontal meridian
How would the geometric effect impacting the right eye cause the gaze normal plane to appear?
Tilted away on the right side
What would a meridional size lens of axis 180 do to an image?
Magnify image in the vertical meridian
What kind of disparity would magnification in the vertical meridian of one eye create?
Vertical disparity
What effect does vertical magnification over one eye produce?
Induced effect
With the induced effect, which horopter rotates? Which horopter does not rotate?
AFFP horopter rotates
IVD horopter does not rotate
What effect occurs when magnification of one eye is 5% greater than the other eye?
Geometric effect
Unopposed because the induced effect breaks down
Will the induced effect and geometric effect ever cancel each other out? If so, when?
Yes
With small amounts of overall magnification
Around what axis do the induced and geometric effects cause the gaze normal plane to appear to rotate?
Vertical axis
Around what axis does the oblique effect cause the gaze normal plane to appear to rotate?
Horizontal axis
What is declination?
Rotation of the vertical meridians toward the magnification meridian in oblique magnification
What effect do Base Out prisms have on the gaze normal plane?
Plane appears to bend toward the observer
What effect do Base In prisms have on the gaze normal plane?
Plane appears to bend away from the observer
Which half of the empirical horopter exhibits a tilt away from the observer?
Top half tilts away
Which half of the empirical horopter exhibits a tilt toward the observer?
Bottom half tilts toward
