Anomalous Correspondence
What is the formula for angle of anomaly?
*<A = <D - <S* BO is positive BI negative a positive <A = crossed separation of foveal tags a negative <A = uncrossed separation of foveal tags
What is the Objective angle of deviation (<D)
-angle the visual axis of the deviating eye fails to intersect with the target -also the angle between zero measure point and fovea of deviating eye -Obtained through CT
Examples: • Cover Test: 10 Δ BO (CRET) • Patient notes that the red and white light are aligned • What is the subjective angle? • What type of correspondence does this suggest?
0 HAC
What are the three types of anomalous correspondence?
1. harmonious AC (HAC) 2. unharmonious AC (UHAC) 3. padoxical AC (PAC) - type 1 - type 2
• Cover Test: 15Δ CRET • Patient notes crossed diplopia • Neutralize with 5Δ BI • What is the angle of anomaly? • What type of correspondence does this suggest?
20 (BO is positive and BI negative) PAC I
• Objective Angle: 25Δ BO • Patient has 5Δ nasal EF • Subjective Angle: 40Δ BO • What is <A(True)? • What type of correspondence does this patient have? • What will you see on the douse test?
30 PAC II movement in (they are really a 30PD BO and your giving them 40BO, they're obviously gonna move in more)
What is HAC? The only type of AC where the pt has a perfect adaptation, where they actually avoid diplopia
<A = <D point Z of deviating eye has same visual direction as fovea of fixating eye (a)
What is Type I PAC?
<A is greater than <D - often happens after strab surgery in pts that previously had AC. The pts cortical correspondence still will remain
When do we have to correct for EF?
<Dt = <Dm + <EF or <At = <Am + <EF nasal <EF is positive temporal <EF is negative
What is the subjective angle of deviation in HAC?
<S = 0 -subjectively everything is aligned to the pt - they won't have stereo bc they aren't bifoveal but they are using the Z point so they're good
What is Type II PAC?
<S is greater than <D - often happens after strab surgery in pts that previously had AC. The pts cortical correspondence still will remain
What is UAC?
<S is less than <D, but still greater than 0 Will have double vision but minimal
Your pt has a 40Δ CRET with normal fixation. What do you expect to see on HBAIT if the patient has normal correspondence?
A perfect cross
If pt reports two lights and have crossed diplopia, you'll add (BI or BO) prism until pt reports light is in the middle
BI Perform UCT: No movement = NC Movement =AC
• Cover Test: 20Δ CLET • Patient reports uncrossed diplopia • What type of prism do you add? • Patient notes the lights are aligned at 10Δ BO • What is the angle of anomaly? • What type of correspondence does this suggest?
BO 10 UHAC
If pt reports two lights and have uncrossed diplopia, you'll add (BI or BO) prism until pt reports light is in the middle
BO Perform UCT: No movement = NC Movement =AC
Tests thats Indirectly determines <A
By determining the obj and subj angle and using the formula to calculate the angle of anomaly
Step 3:
Compare <D to <S
Whats the point of the Red Lens test for correspondence?
Compare <D to <S
Crossed or uncrossed? What type of correspondence does this suggest?
Crossed PAC I
Crossed or Uncrossed foveal tags?
Crossed foveal tags
Positive <A(measured) -->
Crossed separation
Step 2:
Determine <S Put vertical prism and red lens over one eye to create diplopia and ask pt what they see add BO for uncrossed and BI for crossed diplopia until patient reports alignment (like buttons on a shirt)
What is the point of this test?
Determining <S (Subjective Angle)
What is the problem with the Sensory theory?
Does not account for UHAC Errors in testing like: -EF -Measurement error
T/F: Bagolini Test has the most unnatrual condition of viewing things?
F, Test conditions are the most natural. Similar to normal viewing conditions
T/F: It takes EF into account to determine <A (measured)
F,<A (true)
Your pt has a 40Δ CRET with normal fixation. What do you expect to see on HBAIT if the patient has harmonious anomalous correspondence?
Foveal tag 40 cm apart
Your pt has a 40Δ CRET with normal fixation. What do you expect to see on HBAIT if the patient has PACI (subjective angle of 10Δ XT)?
Foveal tags 50 cm apart
What type of correspondence does this suggest?
HAC
UCT movement =
HAC -they're strabismic even though they're reporting fusion
If pt has EF-->
If fovea corresponds with EF to make a perfect cross this is AC
Suppression
If they have a more peripheral suppression they may suppress more of the line but if its more of a central suppression they'll just suppress the centeral area
What's the point of the major Amblyoscope?
It indirectly measures the <A by measuring subjective and objective angles of deviation
HBAIT procedure
Last step: -Center horizontal line on center point -Then ask pt where they see vertical line = measured<A
Step 1:
Measure <D (ACT)
Whats the point of Haidinger's Brush + After Image Transfer test
Measures <A(true) directly It takes AC and EF into account in one test! awesome So it measures <A(true) directly, don't even have to take EF into account bc its already doing it for me Useful for small angle strabismic patients with EF Flash vertical AI to the good eye Occlude good eye, have strab eye to view Haidinger's Brush
UCT no movement =
NC
If pt has no EF -->
NC and a perfect cross
Amblyoscope problems • Cover Test - 25Δ BI • Subjective Angle - 30Δ BI • and there's movement on the Douse test • What type of correspondence does this patient have? • What if the patient has 5Δ temporal EF?
PAC II -25 - 5= -30. Makes them a NC
If a pt reports one light in the middle, <S=0, How do you differentiate b/w a NC and a HAC?
Perform a Bagolini UCT
Your pt has a 40Δ CRET with normal fixation. What do you expect to see on HBAIT if the patient has unharmonious anomalous correspondence?
She just picked 20 bc less than 40 but > 0 Foveal tags 20 cm apart
T/F: Correspondence status changes when patient is strabismic v. when pt is aligned
T Typical in IXT. Changing the status of their correspondence when they go from aligned to strabismic
T/F: The HBAIT test DIRECTLY measures the <A (measured), not the <A true or <S
T bc it uses foveal tags to measure
Why is it a must to do UCT if pt is aligned on W4D?
To see if they have NC or HAC
T/F: THIS IS A CORTICAL TEST - POSITION OF THE EYES DOES NOT MATTER IF THEY ARE AN ET, XT, OR ENUCLEATE THE EYES!!!
True!!
• Objective Angle: 40Δ BO • Subjective Angle: 20Δ BO • What type of correspondence does this patient have?
UHAC
Crossed or uncrossed?
Uncrossed
Exception: Your pt has a 40Δ CRET with normal fixation. What do you expect to see on HBAIT if the patient has PACII (subjective angle of 50Δ XT)?
Uncrossed
Crossed or uncrossed? What type of correspondence does this suggest? What if this patient had EF?
Uncrossed NC It would effect Obj CT and UCT
Crossed or uncrossed? What type of correspondence does this suggest?
Uncrossed PAC II
Crossed or uncrossed? What type of correspondence does this suggest?
Uncrossed (be careful with where OS and OD are positioned) UHAC
Crossed or Uncrossed foveal tags?
Uncrossed foveal tags
Negative <A(measured) -->
Uncrossed separation
What is the angle of Anomaly (<A)?
angle between *fovea* of deviating eye and *point a* how far off the fovea (F) is the point that we're using to correspond (a)
What is the subjective angle of deviation (<S)?
angle between point Z and point a - the pt's perceived size of deviation hence subjective
In PAC I, how will an XT subjectively respond?
as an ET
In PAC I, how will an ET subjectively respond?
as an XT
Which is more likely to develop AC, constant strab or alternating strab?
constant - stable angle of deviation - comitant angle
In normal correspondence, the subjective angle of deviation is ____ (equal; not equal) to the objective angle of deviation <D.
equal
True or false, AC usually occurs in large angles of strabismus.
false - small to intermediate angles - common in microstrabs
Will a pt with HAC report diplopia.
no - pt is subjectively ortho - <D will be greater than 0
In AC, the subjective angle of deviation is ____ (equal; not equal) to the objective angle of deviation <D.
not equal
What is the associated point (Point a)?
retinal point in deviating eye that when stimulated gives rise to the same visual direction as the fovea in the fixating eye the point that the fixating eye is associated with
What are the two ways that pts can eliminate diplopia and confusion from strabismus?
suppression develop anomalous correspondence
When describing the depth of AC: If AC is under more dissociating conditions --> the more _____
the more embedded, more difficult to treat
Will a pt with UAC report diplopia?
yes - pt has subjective angle of deviation
The ___ (younger; older) the age of onset of strabismus the more likely AC will develop.
younger
What is point Z?
zero measure point retinal point in deviating eye that is acting as the fovea
Sensory Theory
• AC is an acquired sensory adaptation • That its our brains adaptation to the strabismus • Basically restoring binocularity to a system thats broken • Pt has NC at first then becomes AC slowly over time --> begins shallow --> deep • As AC becomes embedded, more difficult to elicit NC under any circumstance
Innate Theory (less looked at)
• AC is the cause of strabismus, not the result of strabismus • State of correspondence (AC) is present at birth
What are the 3 theories of sensory development?
• Innate Theory (Hering 1864) • Sensory Theory (Burian 1945) • Motor Theory (Morgan 1961)
How can the sensory theory explain UHAC?
• UHAC initially -->then to HAC • UHAC occurs following a change in <D • Point to large area of correspondence in AC versus point to point correspondence in NC
In PAC II Subjective angle exceeds the objective angle
• XT subjectively responds as a larger XT • ET subjectively responds as a larger ET
