Binocularity Flashcards
What are the two main components of binocularity?
Motor function and sensory function
What is motor function?
Control and coordination of eye movements to place the image on both foveas for the sensory sytem to interpret
What are the two components of motor function?
Maintain bifoveal fixation and prevent blur due to retinal image motion
Tonic vergence
Physiological position of the eyes at rest maintained by EOM tone
Proximal vergence
Nearness of an object stimulates convergence reflex
Accommodative vergence
Convergence driven by accommodation and blur
Fusional/disparity vergence
Completes vergence response for fusion or singularity
Corresponding retinal points
Pairs of points on the retina that give rise to the same visual direction based on final point on visual pathway
Vieth-muller circle
Theoretical circle around the cyclopean eye of all corresponding retinal points
Horopter
All points in object space that stimulate corresponding retinal points
What is the region of highest relative stereopsis?
Horopter
Panum’s fusional area
Slack in front of and behind the horopter that allows us to see a clear single image, non-corresponding retinal points
Physiologic dipolopia
Normal, expected diplopia found outside of panum’s fusional area
Retinal disparity
Each eye’s slightly different view of the same object due to placement of the head
What allows for stereopsis?
Retinal disparity
What drives retinal disparity?
Non-corresponding points
Crossed disparity
Points from temporal retina stimulate convergence
Object is closer than original point of fixation
Uncrossed disparity
Points from nasal retina stimulate divergence
Object is further from original point of fixation
Stereopsis
Binocular perception of 3D space based on retinal disparity
What is the reason for binocularity?
Stereopsis
What is the goal of binocular assessment?
To maintain SCCEBV
What is SCCEBV?
Single, Clear, comfortable, effecient binocular vision
What are the two categories of binocular dysfunction?
Weak or absent
What are weak binocular skills?
Reduced from normal values
Cannot keep up with visual demands of patient
Inadequate to compensate for postural abnormalities
What is absent binocular dysfunction?
Patient only uses 1 eye
What are the 3 Ds of 3D vision?
Disparity
Drives motor fusion
Depth
