Flashcards in B13 Deck (92):
What are 3 things you must have to have normal bino vision?
-VA has to the similar in both eyes and produce comparable cortical images in corresponding retinal areas
-muscles must work correctly
-images from each retina must be fused into a single image
What are 9 advantages of bino vision?
-visual efficiency and performance
-sports and gaming
-a spare eye
-larger bino field/blind spot coverage
-better appreciation of dynamic relation between body and environment
What are 7 problems with abnormal bino vision?
If someone has no stereo what does this mean?
They have no bino vision
The collection and integration of information received at the retina and transmitted to the cortex
T/F: if is sensory fusion is affected by any condition, integration of the images from the 2 eyes will be abnormal
What is the fundamental part of vision?
Name 7 causes of motor dysfunction
-latent manifestations (phorias)
-vergence quality (facility)
-vergence quantity (amplitude)
When should motor problems be treated?
They should be treated last after identified sensory and integrative problems have been treated
Name 5 causes of integrative problems
-aniseikonia (different size retinal images)
-anomalous retinal correspondence
-horror fusions (inability to fuse)
Name the 5 causes of sensory dysfunction
-accommodative insufficiency and infacility
What is considered normal single bino vision?
Bifoveal with no deviation
What is considered abnormal bino vision regarding the fovea?
When the fovea of one eye projects with a non fovea point of the other eye
Is misalignment usually present with abnormal bino vision?
Localized the visual percept in a visual direction that is relative to the direction of the fovea
If the eyes are properly aligned, an image is received on ___ areas of the retinas
If the eyes are functioning normally, will the images will be the same size and color?
What 4 things does the stimulus perceive when the retinal areas is stimulated?
T/F: matching retinal elements have different visual directions
False. They have the same visual direction
Considered the retinomotor zero point
T/F: all points in space falling along the visual line have the same visual direction
This is used to build interpretation of 3D images in space
What 2 things are normal when there is precise and clear bifoveal fixation?
Bino vision and fusion
If there is abnormal bino vision is the visual direction the same or different?
What is the principal visual direction and the center?
In strabismus, this is when a non-fovea point assumes the characteristics of the principal visual direction
Is visual direction subjective or objective?
Is the line of direction subjective or objective?
The line that connects an object with its image on the retina
Line of direction/visual axis
When the visual axes of the fovea intersect at a fixation point
When objects simultaneously stimulate the fovea of both eyes, the object is in the ___ subjective visual direction
When only one line of direction goes to fixation
The ability for visual neurons to process direction and to identify fixed direction in space
A pair of points in each eye when stimulated appear to lie in the same visual direction
Corresponding retinal points
T/F: any disruption at the fovea will lead to a disruption in visual direction
A point 1 degree nasal to the fovea in one eye corresponds to a point ___ to the fovea in the other
1 degree temporal
A plane in space where all points appear to have the same depth
T/F: points not on the horopter are seen by different retinal areas, producing double
A circle that passes through the center or the rotation of both eyes and the fixation points
Does the vieth-muller circle become bigger or smaller when the point of fixation is nearer?
A narrow band around the horopter that allows objects from disparate/dissimilar retinal points to be seen as single
Panum’s Fusional Area
Panums fusional area is ___ around fixation and becomes ___ into the periphery
Narrow around fixation and becomes broad into the periphery
What is the purpose of panums fusional area broadening in the periphery?
-to maintain vision because of eccentricity
-to eliminate diplopia in the periphery
Does eccentricity increase or decrease vision?
T/F: The panums fusional area for a sharply focused fast object is not as wide a for a fuzzy and slow moving target
T/F: fusion is possible if a target falls within the panums fusional area with little disparity
What is physiological diplopia?
Diplopia that is elicited by points off the horopter
When is physiological diplopia seen?
When a target does not lie on the horopter and is outside the panums area
When we have diplopia will the retinal elements be in the same or different directions?
2 different directions
When 2 nasal retinal elements do not have the same visual direction, this will cause ____ which is ___ the horopter
Causes uncrossed diplopia beyond the horopter
When 2 temporal retinal elements do not have the same visual direction, this will cause ____ which is ___ the horopter
Cause crossed diplopia before the horopter
When will the image fall on the horopter?
When the visual direction is on the temporal retinal element OS and a nasal retinal element OD
The unification from both eyes to form a perception
Fusion needs similar ___ and ____
Shape and size
Why does fusion near the fovea only tolerate little dissimilarity between images
Because of the small receptive field
Where is dissimilarity tolerated?
In the periphery where receptive fields are larger
Integration of images on corresponding retinal points to form a single percept.
Vergence movement to maintain retinal images at corresponding retinal points.
Deviation between the empirical horopter and the vieth muller circle
Hering-holler and deviation
Are disparities perceived as one in the panums fusional vertical or horizontal?
Name 3 characteristics of the peripheral VF
-reduce VA due to increased eccentricity
-larger receptive field
-diplopia is less bothersome because of the expanded panums fusional area
____ of the optic nerve at the chiasm gives rise to retinal elements that are corresponding retinal points
Decussation is important for what 2 things?
Bino vision and stereo
List the pathway of processing visual information to a single perceived image
Visual info—> optics nerve—> optic tract —> LGN —> Visual cortex—> single perceived image
T/F: Physiological diplopia means the patient can only use one eye
False. The patient can use both eyes
T/F: Corresponding retinal points that have the same visual direction DO NOT give information about depth or the 3D quality.
Images are projected differently with one eye at a time
When precepts from both eyes merge, why is there depth?
Because the disparity in the projection of the individual eyes
Does horizontal or vertical retinal disparity offer depth?
Is stereo a higher form of bino or mono cooperation?
Is depth perception considered a bino or mono cue?
What type of monocular cues does depth perception have?
Depth perception is seen in what 2 things?
Local stereo and 3D movies
Is stereo learned or acquired?
When will a child develop stereo?
Is depth perception learned or acquired?
Learned. You get it from experience and learning how to judge distance
Mono Cue: same distant subject appear smaller than the same subject at near
Mono cue: an object in front covers an object that is behind.
Mono Cue: an object that is near appears to have a shorter excursion than a distal object when you move your head. (Closer objects appear to move faster)
Mono Cue: solid objects cast a shadow. The position of the shadow shows depression and elevations
Mono Cue: if an object is bigger, it is judged as nearer.
Size of known object
Mono Cue: the object that interrupts contour of another is seen as being in front.
Simultaneous binocular perception of dissimilar objects that are projected in the same direction
First degree fusion
Single simultaneous, binocular perception of identical targets with dissimilar parts (suppression check)
Second degree fusion
Fusion of disparate targets, resulting in a 3D percept.
3rd degree fusion
Theory: There is a one to one retino-cortical relationship between the eyes. A given retinal area (point AR) shares a common subjective visual direction with an area of the other retina (point AL).
Correspondence and disparity theory
When dissimilar retinal areas are stimulated by one object, what is reported?
Does depth increase or decrease with disparity?
If disparity persists, what occurs?
Does disparity increase or decrease the quality of stereo?
T/F: The receptive field of a visual neuron/cell is the part of the visual field that can influence the firing of that cell.