Assessing Correspondence Flashcards
What is the perception of two of the SAME object projected in Different visual directions?
Diplopia
What is the perception of two different objects projected in the SAME visual direction?
Confusion
Suppression
perceptual solution for diplopia/ confusion
What is the cortical reprogramming of the visual directions of various points of the retina?
anomalous correspondence
aka: ARC
What is it called when the foveas of the eyes are cortically linked so that images projected on the foveas are cortically combined to form a single percept in a common visual direction?
Normal Correspondence
How is AC different than EF?
AC: binocular; exists to fix a problem (diplopia or confusion); harmonious: able to fuse
EF: monocular; IS the problem; only comes into play when the eye is fixating (d/t suppression)
can happen at the same time
What is point Z?
Location of the image of the object of regard in turned eye
where the image we are looking at falls on the retina
NOT a fixed location
What is point a?
location in turned eye associated with fovea of fellow eye
fixed location; “anomalous point”; can be moved with VT
cortically linked to the other eye; can be at point z or any other point
objective angle (<D)
angle from where the image of the object is located on the retina (Z) to the fovea
from Z to F as the eye rotates
assessed with PACT, MA
Subjective Angle
Angle from Z to the point in the eye that corresponds to the fovea of the other eye (a)
assessed with MR, red lens, HL, etc
What is the angle of anomaly (<A)
Angle from the fovea to the anomalous point
assessed with HBAIT
find <D and <S; angle of anomaly is whatever is left; usually calculated; if the same, no AC
Harmonious Anomalous correspondace
When the objective angle equals the angle of anomaly
Which two points are in the same place in harmonious Anomalous Correspondence?
Z and the anomalous point
In HAC, why doesn’t the patient report diplopia?
The subjective angle is always zero
the anomalous point is where the image is
What does the patient perceive in Unharmonious anomalous correspondence?
A smaller deviation than what is actually there
Where is the anomalous point in UAC?
closer to the fovea than in HAC
When does Paradoxical Anomalous Correspondence occur?
Typically post surgery
Where is the anomalous point in PAC II?
on the opposite side of the retina than expected
patient will perceive a larger deviation than what is actually there
Where does the patient perceive the deviation in PAC I?
deviation in the opposite direction than what is actually there
Example: an esotrope will report crossed instead of uncrossed diplopia
What are the 3 theories of AC development?
- Innate
- Motor
- Sensory
What is implied in the innate theory?
AC is the cause of strabismus rather than the result
contradictory evidence exists
What type of eye movements under the motor theory produce changes in both eye movements AND correspondence?
registered eye movements
impulse from brain changes location of the eye and indicates which correspondence to use (perceptual processesing area of brain responsible for visual direction)
Which theory states that strabismus and AC are separate anomalies with a common neurological source?
Motor theory
whatever cuased the eye turn, also changed the directional sense
According to the motor theory….
Which type of eye movement is accommodative vergence?
Non-registered Eye Movement
impulses from brain communicate only with EOMS; produce only eye mvmt
What is shifted to match the motor deviation under the sensory theory of AC development?
primary visual diretion
helps restor some semblence of binocularity
What happens to AC over time according to the sensory theory of AC development?
AC deepens over time
Bc AC is sensory adaptation to abnormal motor conditions it requires time to become embedded
Which type of AC does sensory theory explain?
Harmonious AC
there are problems with UAC
Why might different tests for AC provide different results?
- embeddedness
- measurement error
- unsteady EF
- Variation in deviation magnitude between tests
Eccentric fixation in the same direction does what to the full amount of the angle of anomaly?
it hides it
nasal EF w ET, EF will mask angle, measured will be smaller than true
also hides full amount of objective angle
Which type of strabismus is the Haidinger’s brush and afterimage test ideal for?
small angle strabismus
What is measured by HBAIT?
angle of anomaly with concurrent assessment of EF
What tags the fovea of the deviated eye in HBAIT?
the brush
if the brush and the afterimage are in the same place, what type of correspondence does the patient have?
Normal
How is Worth 4-dot used to assess correspondence?
comparing subjective and objective angles
UCT/ douse is used to determine what?
anomalous correspondence
For worth 4 dot for correspondence, which type of prism is used?
corrective
uncrossed = base out; crossed = base in
