Term
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Definition
| VA and contrast threshold is better with 2 eyes |
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Term
Aiming of the 2 eyes can produce:
Use of two eyes gives --> |
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Definition
amblyopia
suppresion
diplopia
Larger field of view |
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Term
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Definition
| no overlap b/w the 2 eyes and can see almost 360 around them |
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Term
| Human have VF that overlaps : |
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Definition
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Term
Binocular VF
Temporal cresents |
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Definition
overlapping part of the VF is seen by both eyes at the same time
lies b/w the temporal cresents
VF seen by one eye alone |
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Term
interocular distance
septum |
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Definition
60-65 mm; why we see 2 different scenes mono,
the image on the retina's of both eyes are NOT indentical
nose divides and cuts the extreme nasal part of each eye's VF |
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Term
Real advantage of bino vision :
STEREOPSIS |
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Definition
bino form of depth perception
allows more precise hand-eye coordination
grasping near objects is more accurate under bino
lower detection thresholds
increased VA |
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Term
| Can judge some things with mono cues to get depth perception ( depth is still better bino) |
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Definition
- perspective
- occlusion
- elevation
- texture gradient
- motion parallax |
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Term
| people with bino vision abnormalities |
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Definition
- judge distances differently
- see objects in the wrong location
- see the world as distorted |
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Term
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Definition
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Term
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Definition
| integrate the images of objects viewed by the 2 eyes as a single image |
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Term
Limits of depth perception :
1. steroacuity
2. panum 's ranges |
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Definition
small depth without loss of fusion
largest depth without loss of fusion |
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Term
Improper conditions to see singly:
1. diplopia
2. binocular rivalry
3. Binocular suppression |
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Definition
each eye's image does not combine fully but instead fights to win out over the other eyes image
- one eye shuts off |
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Term
The location of an object in space is determined by:
VISUAL DIRECTION
DISTANCE |
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Definition
- 2D localization of objects, taking account only the lateral and vertical position of the object regardless of distance
- is a measure how far away the objects is, depends on visual direction, interrelated with object size |
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Term
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Definition
what direction the light of an image is coming from
used to build an interpretation of the 3D world ( visual space) |
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Term
LOCAL SIGN
made possible by : |
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Definition
capacity of visual neurons to process direction
Retinotopic mapping of neurons in the visual system and labeled lines
- an image formed on a specific retinal location will stimulate a retianl location, LGD, or striate cortex |
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Term
KEY POINT:
Visual space is not exactly the same as real space.
OPTICAL ILLUSIONS |
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Definition
| - are the result of mismatches b/w visual space and physical space |
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Term
| Visual Line/line of sight |
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Definition
representation of visual direction
- projects from a given point on the retina passing thru the nodal pt. of the eye into physical space
- ALL points in space falling on this line at any distance appear in the same direction in the VF |
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Term
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Definition
| visual line that passes from the fovea to object of regard |
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Term
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Definition
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Term
| Principle visual direction |
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Definition
- reference in which we compare all
direction
zero direction
direction signaled by the fovea/where the eye is fixating |
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Term
| Secondary Visual Direction |
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Definition
area's around the fixation pt
signaled by retinal pts eccentric to fovea
rt, lt. above below fixation pts |
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Term
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Definition
"eye centered" visual direction so that as the eye shifts position so does the oculocentric direction
- is determined by the line of sight of an object thru the nodal pt. of the eye to the retina |
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Term
| Law of occulocentric visual direction |
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Definition
| superimposed retinal images will be seen in the same occulocentric visual direction |
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Term
| central serous maculopathy |
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Definition
fluid beneath the retina dislodges the PRs
results in metamorphospsia (spatial distortion of vision) |
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Term
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Definition
point other than the fovea is used for fixation
- common consequence of strab's and contributes to vision loss of amyblopia
- a pt. who fixates at an extrafoveal retinal locus does not necessarily have eccentric fixation
- neurological remapping of monocular principal visual direction to a new locus |
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Term
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Definition
- in low vision pt. may chose an extrafoveal fixation pt
- pt. selects a retinal locus w/ better resoln. than the diseased fovea
- pt. still uses destroyed fovea as zero direction /principal visual direction is unchanged |
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Term
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Definition
1, develops in childhood in concert with strab and amblyopia
2. pt not aware of the problem
3. use visuoscopy to see if the foveal relex does not appear in the center of the target |
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Term
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Definition
requires conscious effort on the part of the pt
it occurs after loss of vision from injury or DZ
it is a normal adaptation to the visual loss rather than an abnormality |
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Term
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Definition
| visual direction is dependant on feedback from other sensory organs and may be altered under certain cirumstances |
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Term
past pointing:
paretic muscle |
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Definition
| when fixation is attempted in the field of action of the paretic muscle, the pt. will reach past an object perceiving it to be beyond its actual location |
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Term
| Headcentric directionality |
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Definition
| knowledge of the position of the eyes in the head |
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Term
| Law of headcentric localization |
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Definition
| for a given postion of the eye in the head, objects lying on the same line of sight are seen in the same headcentric visual direction |
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Term
| Law of identical visual direction |
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Definition
objects with same visual direction in each eye will be seen as lying in a single visual direction under bino viewing conditions
-fovea 's of the 2 eyes signal the same primary visual direction |
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Term
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Definition
| under bino conditions we see directions not relative to each eye alone but relative to this single reference point w/in our head |
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Term
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Definition
| we see objects whose images are formed on both fovea's as if their images instead fell on a single pt. midway btw the 2 eyes; |
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Term
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Definition
| imaginary single eyeball in the middle of the head |
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Term
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Definition
| reflects the relative weighting of each eyes input into the bino precept |
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Term
| Corresponding retinal points |
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Definition
| pairs of points, one in each eye that when stimulated simultaneouly or in rapid succession are perceived to lie in a single common visual direction |
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Term
| common subjective principal visual direction |
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Definition
zero reference for bino direction
originates from a pt. midway b/w the two eyes |
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Term
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Definition
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Term
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Definition
| plot of points in visual space and their corresponding retinal pts, |
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Term
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Definition
| corresponding pt. are "zero" pts. for stereopsis |
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Term
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Definition
| arises from the stimulation of noncorresponding retinal pts. |
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Term
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Definition
images of a single object that do not stimulate corresponding retinal pts in the 2 eyes
if viewed mono images are perceived as lying in different visual directions |
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Term
Binocular disparity
too large of a bino. disparity |
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Definition
difference in position in relation to corresponding pt. bw images in the 2 eye
DIPLOPIA |
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Term
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Definition
| vertical differences in positions of similar images |
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Term
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Definition
horizontal differences in retinal image position
* more impt*
- allows the perception of stereoscopic depth
- can be crossed or uncrossed depending of fixation pt |
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Term
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Definition
pt. seen as nearer than the fixation pt, fall w/in Vieth-Muller circle, and have a line of sight that cross in front of the fixation pt.
positive AL is larger than AR
temporalward shift of images in one or both eyes |
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Term
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Definition
-points further away than the fixation pt. have lines of sight that meet behind the fixation pt.
- angle n is negative
- AR is larger than AL
- nasalward shift |
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Term
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Definition
| small differences in perceived horizontal direction btw the 2 eyes give rise t a 3d percept |
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Term
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Definition
| images on widely separated noncorresponding pts or pt beyond Panum's area will not be seen as fused or single |
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Term
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Definition
distant object is fixed bifoveally
a nearer object in front of it will be imaged on the temporalward retina of each eye on noncoressponding pt.
-- if these pt are far enough we see double |
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Term
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Definition
near object is fixated, a distant object is seen as double
each image is formed on the nasal retina |
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Term
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Definition
| two different objects seen in one direction or location |
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Term
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Definition
- should be seen as single pts. lying n a single direction
- pt. lying off the circle, should be seen as arising in two distinct directions--> Diplopically
- nearer pt.-- crossed
- farer pt -- uncrossed |
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Term
| Anamalous retinal correspondence |
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Definition
| strab mya remap the corresponding pt. on the retina without suppression that eye |
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Term
| diplopia and confusion may be eliminated in a strab visual system by : |
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Definition
1. suppressing
2. shifting the zero reference pt. for directionalty in the strab. eye |
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Term
| diplopia and confusion may be eliminated in a strab visual system by : |
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Definition
1. suppressing
2. shifting the zero reference pt. for directionalty in the strab. eye |
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