The document discusses retinal correspondence and abnormal retinal correspondence (ARC) in patients with strabismus. It defines normal retinal correspondence as when stimulation of corresponding retinal points produces single vision, while ARC is when non-corresponding points produce single vision. ARC can be harmonious, unharmonious, or paradoxical depending on its relationship to the objective angle of deviation. Several clinical tests are described to assess retinal correspondence, including Bagolini's striated glasses test, red filter test, synoptophore, and Worth's four dot test. Occlusion therapy is mentioned as a treatment to prevent worsening of ARC and promote normal correspondence.

1. Vipul Aggarwal
Aditi Jain

2. Normally the two visual axes
meet at the point of regard or
the object of attention. The
eyes are said to be in alignment
.
Due to some unfortunate reason the two visual axes may not be aligned to
the point of regard, results in strabismus or squint.
Thus, binocular vision ,which is an asset with normal alignment of two
eyes, becomes a liability.

3.  Every retinal point has a partner in fellow retina with
which it shares relative subjective visual direction.
 All other points are called DISPARATE POINTS with
its reference.
 Thus image on these corresponding points are
perceived as binocularly single, and those on disparate
points as binocularly double.
 If all corresponding points are projected in space at
any particular distance they form an HOROPTER.

4.  From the Greek words horos (boundary) and
opter (observer).
 The term Horopter (the horizon of vision) was
introduced in 1613 by Aguilonius.
 locus of all object points that are imaged on
corresponding retinal elements at a given fixation
distance.

5. Geometric Vieth Muller horopter
 According to this model of horopter if corresponding
points have a regular horizontal distance from the
retina the horopter would be a circle passing through
the center of rotation of the two eyes and the fixation
point.
Empirical Horopter Curve
In actual practice ,it is slightly flatter than veith muller
horopter.

6. HERING-HILLEBRAND DEVIATION
 Due to both nasal and optical factors – nasal hemi
retina at any given eccentricity contains more
photoreceptors per unit area than temporal hemi
retina producing a deviation in horopter mapping in
visual cortex.

7.  Region in front and back of the horopter in which
single vision is present
 narrowest at the fixation point and becomes broader
in the periphery.
 All objects outside panum’s area give rise to
physiological diplopia.

8.  Physiological diplopia:
a. it exists in the presence of binocular vision.
b. When we fixate on near object, distant object seems
blur- homonymous diplopia
c. When we fixate on distant object, near object
becomes blur- heteronymous diplopia

9.  When squint occurs the two fovea’s view two different
objects and send two different image to single cortical
perceptual area.
 This leads to CONFUSION.
 However cortex immediately settles for one image with
its strong cortical or retinal rivalry.
 Thus confusion is never complained of.

10.  When squint occurs an object is perceived by fovea of
one eye and some extra- foveal point of other eye.
 Thus an object is localized twice in space causing
DIPLOPIA.
 TYPES of diplopia-
HETERONYMOUS DIPLOPIA
HOMONYMOUS DIPLOPIA
PARADOXIAL DIPLOPIA

11.  To escape the disabling and troublesome situation
created by diplopia and confusion , the strabismic
patients develop certain adaptations which allow them
to have a comfortable single vision.
 These sensory adaptations are
1. Suppression
2. Abnormal retinal correspondence(ARC)

12.  This concerns the retinal area of each eye that
have the same visual direction during binocular
vision.
 Retinal correspondence is the inherent relationship
between paired retinal visual cells in the two eyes.
 Images from one object stimulate both cells, which
transmit the information to the brain, permitting a
single visual impression localized in the same
direction in space.

13.  Specifically, the right nasal retina contains points that
correspond to their counterpart in the left temporal
retina, and vice versa.
 When stimulation of corresponding retinal points or areas
produces single vision, normal retinal correspondence is
said to be present.

15.  when stimulation of noncorresponding retinal points
produces single vision, anomalous retinal correspondence
is present.

16. Thus Retinal Correspondence can be of two types:
1. Normal Retinal Correspondence
2. Abnormal Retinal Correspondence

17.  Retinal correspondence is called normal when both
the fovea have a common visual direction and the
retinal elements nasal to the fovea in one eye
corresponds to the retinal elements temporal to the
fovea in the other eye.

18. • Anomalous retinal correspondence (ARC) is a
establishment of a new working relationship
between the fovea of one eye and extra-foveal point of
the squinting eye.
• It is a binocular condition and not a uniocular
adaptation of projection.

19.  This results in the eyes seeing binocularly single
inspite of a manifest squint.
 under binocular conditions the fovea and the
extafoveal point share the common visual direction
 when the normal eye is closed the extrafoveal element
loses any advantage over the fovea of that eye, which
retains its primary visual direction.

20.  Early onset squint
 Constant angle of deviation
 Small angle squint
 Unilateral squint

21.  The angle of anomaly denotes the degree of shift in
visual direction.
 It is determined by calculating the difference
between the objective and subjective angles of
deviation.

22. (1) Harmonious ARC
 angle of anomaly is equal to the objective
angle of deviation ( subjective angle = o)
 This indicates that the
ARC fully corresponds to the strabismus.
 provides a compensation for the angle of squint
 Eliminate the awareness of diplopia and confusion

23. (2) Unharmonious ARC
angle of anomaly is less than the objective angle of
deviation
subjective angle ≠ 0
(3)Paradoxical
when the angle of anomaly is greater
than the objective angle of deviation.
It occurs mainly after overcorrection of the squint
surgery

25.  Clinically the tests used can be based on either of the
two principles:
A) Assessment of relationship between the fovea of the
fixing eye and the retinal area stimulated in the
squinting eye. This includes:
1. Bagolini's striated glasses test
2. red filter test
3. Synoptophore using SMP slides for measuring the
objective and subjective angles
4. Worth's 4 dot test

26.  patient fixates a small light, after being provided
with plano lenses with narrow fine striations
across one meridian.
 lenses are usually placed at 45 degree and 135
degree and the patient fixates for distance or
near.

27. The interpretation of this test is as follows-

28.  place a red filter in front of the habitually fixating
eye while the patient is looking at a small light source
 number of different responses can be elicited.
 patient may report that two lights are seen, a red
one and a white one.


29.  In esotropia the
images appear in
homonymous
(uncrossed)
diplopia,

30.  In exotropia the images
appear in heteronymous
(crossed) diplopia
 This represents NRC.

31.  patient may report that
only one pinkish light in
the position of the white
fixation light is seen
 This is clearly an abnormal
response in presence of
heterophoria. This is
termed Harmonious ARC.

32.  may report that the
measured distance
between the double images
proves to be smaller than
expected from the
magnitude of deviation
 This represents
unharmonious ARC.

33.  The interpretation of this test is as follows-
 Angle of Anomaly = Objective Angle – Subjective Angle
 If Subjective Angle = Objective Angle → NRC
 If Subjective Angle < Objective Angle → ARC
 If Angle of Anomaly = Objective Angle →Harmonious ARC
(full sensory adaptation)
 If Angle of Anomaly < Objective Angle →Unharmonious
ARC

34. • simple test utilizing red-green color dissociation.
• consists of a box containing four panes of glass,
arranged in diamond formation, which are
illuminated internally.
• The two internal panes are green, the upper one
is red and lower one is white.

35. • patient wears red and green goggles (as a convention
red in front of right and green in front of left).
• can be performed separately for distance and near
vision.

36. four dots normal binocular response with no
manifest deviation (NRC with no
heterotropia)
Harmonious ARC with manifest squint
five dots uncrossed diplopia with esotropia, red
dots appear to the right
crossed diplopia with exotropia, red
dots appear to the left of the green dots
3 green dots suppression of right eye
2 red dots suppression of left eye

38.  highly dissociating orthoptic test in which battery-
powered camera flash is used to produce a vertical
after image in one eye and a horizontal after image in
the other eye.

39. • Each eye fixates on the center black mark of a glowing
filament
• horizontally to the better eye
• vertically to the poorer eye for 20 sec in a darkened room
• patient indicates the relative position of the two gaps in
the center of each afterimage
• gaps correspond to the visual direction of each fovea if
central fixation is present.

41.  Displacement between the centres of the two after
images is proportional to the angle of anomaly
 Tan Ø = dispalcement / distance of testing

42. • Cuppers test for retinal correspondence determines
whether the two foveas have common or different
visual directions.
• It permits quantitative analysis of the angle of
anomaly when eccentric fixation is present.

44.  Occlusion Preventive as well as curative measure
 Prolonged alternating occlusion is not recommended
- prevent further development of ARC as well as
normal correspondence
 Exercises with major amblyoscope
1. Stimulation of the foveal area
2. Kinetic bi retinal stimulation