Physiology of Binocular Vision Flashcards
Normal Binocular Vision
bifoveal with no deviation
Abnormal Binocular Vision
fovea of one eye projects with a non-fovea point of other eye
Retinal Element
where stimulus reacts on the retina in relation to the fovea
Matching Retinal Elements
have same visual field
represent corresponding retinal points
Visual Direction
all points falling along a visual line (horopter)
identifies where a light is coming from
subjective
Eccentric Fixation
in strabismus
non-fovea point assumes characteristics of the principal visual direction
Visual Axis
line that connects an object with its retinal image
Monocular Fixation
only one line of direction goes to fixation
Local Sign
ability to identify fixed direction in space
objects in same direction will be in a single visual direction in binocular vision
Corresponding Retinal Points
retinal elements in each eye that lie in same visual direction/ field
Fovea has a _____ receptive field
small
allows for more precise visual direction
Peripheral Retina has a _____ receptive field
large
Metamorphosia
disrupts visual direction at fovea
Horopter
line of vision
objects on horopter project to corresponding retinal points and appear as a single image
Points not on Horopter
seen by different retinal areas
double vision- two different visual directions
Panum’s Fusional Area
narrow band around horopter that allows objects from different retinal points to be seen as single
narrow around fixation, broad in periphery
Broader Panum’s Fusional Area in periphery is because…
maintain vision because of eccentricity, which otherwise causes a decrease in vision
eliminates diplopia
Panum’s Fusional Area and Stimulus
sharp image- smaller area
fuzzy image- larger area
Uncrossed Diplopia
focusing beyond the horopter,
nasal retinal elements do not have same visual directions
Crossed Diplopia
focusing in front of horopter
temporal retinal elements do not have the same visual directions
Obtaining the same visual direction
temporal retinal in one eye with a nasal element in the other
image will fall on horopter
Fusion
unification of both eyes to form an image
image needs to be the same size and shape
dissimilarity is tolerated better at periphery than at fovea because of larger receptive field
Sensory Fusion
integration of images on corresponding retinal points to form an image
Motor Fusion
vergence movement to maintain retinal images at corresponding retinal points
