Eye Movements and Stereopsis Flashcards
What is HEring’s law
All voluntary conjugate movmeents equal and simultaneous innervations flow from ocular motor centres to themuscle sestablishing the direction of gaze
What are yoked msucles
Muscles athat contract to move both eyes in the same direction
What is vergence?Sm
Movmeent of the eyes in opposite directions - slower than versions and stimulated by retinal disparity
What are corresponding retinal poitns?
Same angular distance from the two foveal cntres
Connected to approximately the same areas of the visual cortex
What is a horopter?
A line in space connecting a set of points whose binocular disparity is zero
What is Panums area
A region bordering a horopter - images found in this area will be perceived as single even if they fall on slightly non-corresponding retinal points
What is visual direction
A stimulus that falls on corresponding retinal points in two eyes and is thereofre perceived as being in the same visual direction whichever eye views the stimulus
Requires normally functioning extra-ocular musclesW
What is sensory fusion
images that have a slight binocular disparity but fall inside Panum’s area will be perceived as single
What is dichoptic simulation
If dissimilar images or contours are present in the same retinal area a binocular rivalry will develop
What is stereopsis
Ability to use binocular disparities to perceive distance in the third dimension of space
The ability to see an object in three dimensions
How is stereopsis measured?
Stereoscope mesures angle of convergence required to fuse images from two slightly dissimlar objects using two base out prisms.
Random dot stereogram, Frisby test measure stereoacuity - these remove error from monocular cues and use a camoflauged object in which elements that are non-resolvable are presented in a random pattern at different dispaties - ability to pervceive depth and form is assessed
What is diplopia
Sensation produced by stimulating two points outside Panum’s area
Where does the image fall in a crossed diplopia?
Temporal retina
Uncrossed diplopia image?
Nasal retina
