Assessing Sensory and Motor Fusion Flashcards
Prism moves images to the _________ and light to the _________
apex, base
What is the process by which the stimuli individually sensed by each eye is combined to form a synthesized single percept?
sensory fusion
occurs in the brain; the ability to “see” single; despite having 2 eyes with different views of the world
Which type of fusion consists of relative movements of the eys to achieve simultaneous retinal stimulation of corresponding retinal areas?
motor fusion
the movements of the eye that allow sensory fusion to occur
What is 1st degree sensory fusion?
superimposition of two distinct images
What is 2nd degree sensory fusion?
Fusion of 2D images; “flat fusion”
What is 3rd degree sensory fusion?
stereovision
What is the inability to perceive normally visibly objects in all or part of visual field?
suppression
often around fovea/macula with periphery intact
What is the cause of suppression?
active cortical inhibition
Why does suppression occur?
in order to preserve semblance of binocularity
What are the two theories of the development of suppression?
- classical model
- Pratt-Johnson
Under the classical model of suppression, how many areas must be suppressed?
two areas must be suppressed
fovea: elimination of confusion; peripheral retinal point: elimination of diplopia
Where is the zone of suppression under the classical model of suppression?
From F to Z
Under the Pratt-Johnson theory of Suppression, where does suppression occur in patients with strabismus?
strabismic patients without fusion suppress area of overlap in deviated eye
assumes a binocular field of vision
Hemi-retinal trigger in ET
trigger of a temporal point (by prism, or surgery), leads to diplopia while trigger of a nasal point will lead to suppression
XT is opposite
when is suppression bilateral?
alternating strabismus