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1. Optom. Ankit S. Varshney
B.Optom, M.Optom, Ph.D. in Optometry (pursuing) Fellow of IACLE (Aus.), Fellow of ASCO(Mum.)
Prof. at (Shree Bharatimaiya College of Optometry & Physiotherapy, Surat)
Life Member of Indian Optometric Association (IOA)
Associate Member of Association of Schools and Colleges of Optometry(ASCO)
Member of Optometry Council of India(OCI)
Educator Member of International Association of Contact lense Educators (Australia)(IACLE)
Mail id: ankitsvarshney@yahoo.com
Whatsapp no. +918155955820
ALPHABETICAL PATTERN
Vertically incomitant
Horizontally comitant deviation

2. References
 BINOCULAR VISION & STRABISMUS –GK VON NOORDEN
 CLINICAL MANGEMENT OF STRABISMUS ELEZABETH
E.CALAROSSA & MICHAEL W. ROUSE
 AAO- SECTION: PEDIATRIC OPHTHALMOLOGY &
STRABISMUS
 STRABISMUS SIMPLIFIED- PRADEEP SHARMA
 PRACTICAL ORTHOPTICS IN THE TREATMENT OF SQUINT-
LYLE AND JACKSON’S
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3. Types of strabismus
 1. Apparent/ Pseudo Strabismus: nothing but an optical
illusion caused by prominent epicanthal folds (pseudo eso)/
wide IPD (pseudo exo).
 2. Latent Strabismus (Phoria): deviations are present only
some of the time: (interruption of BV, fatigue, illness,
stress)
 3. Manifest Strabismus (tropia): eyes deviated all the time
 Concomitant ( Non-paralytic)
 Incomitant strabismus: Manifest squint in which the
amount of deviation varies in different directions of gaze. 7/15/2020Optom. Ankit varshney3

4. A-V pattern
 It denotes the fact that there is a
considerable difference in the angle of
horizontal deviation on looking upward as
compared with looking downwards.
 It can be exodeviations or esodeviations
that measure differently in upgaze, primary
position and downgaze.
 As the eyes move from upgaze to
downgaze, instead of making parallel
upward and downward movements, the
eyes move up and down in particular
pattern.
 This pattern can have the configuration of
A, V, X, Y,◊ or .
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5. TYPES
1) A-pattern :-
 “A” phenomenon in ESOphoria
and ESOtropia:- On looking
directly upwards, the convergent
deviation is considerably greater
than when looking directly
downwards.
 “A” phenomenon in EXOphoria
and EXOtropia:- On looking
directly downwards the divergent
deviation is considerably greater
than when looking upwards.
Eso ↑ Upgaze
Exo ↑ Downgaze 7/15/2020Optom. Ankit varshney5

6. “A”phenomenon
 The term applied to those cases which show a
considerable increase in the angle of
convergence (or decrease in the angle of
divergence) on upward gaze.
 Considered significant if deviation differ by 10 Pd
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7. 2) V-pattern:-
 “V” phenomenon in ESOphoria and
ESOtropia:- On looking directly
downwards the convergent
deviation is considerably greater
than when looking directly upwards.
 “V” phenomenon in EXOphoria and
EXOtropia:- On looking directly
upwards the divergent deviation is
greater than when looking directly
downwards.
TYPES
ESO ↑ Downgaze
EXO ↑ Upgaze 7/15/2020Optom. Ankit varshney7

8. “V” phenomenon
 The term applied to those cases which show a
considerable increase in the angle of convergence (or
decrease in the angle of divergence) on downward
gaze.
 Considered significant if deviation differ by 15 Pd
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9. “X” pattern
 “X” pattern or “X” exotropia:- The EXOdeviation more
in upward and downward gaze and less in the primary
position.
 Patients with X pattern may fuse in primary position
but not necessarily
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10. “Y” pattern
 “Y” pattern or “Y” exotropia:- The EXOdeviation more
only in the upward gaze . Same and less in primary
position and downward gaze.
 Patients with Y pattern may fuse in primary position but
not necessarily
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11. “◊” pattern
 “◊” pattern or “◊” exotropia {Diamond exotropia
:- The exodeviation is more in primary position.
Eyes are more closer or divergence less in the
upward and downward gazes.
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12. “” pattern
 “” pattern or “” exotropia:- The exodeviation is
more only in downward gaze. Same and less in
primary position and upward gaze.
 Patients with  pattern may fuse in primary
position but not necessarily
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13. The physiological variation
 This happens in the normal eyes in the absence
of any squint.
 In this, there is a slight relative divergence in
supraversion and a slight relative convergence in
infraversion.
 It is considered ‘physiological’ only if it is of
slight degree.
 The difference in the angle of deviation on 7/15/2020Optom. Ankit varshney13

14. While measuring the A-V pattern, certain
criteria's considered are:-
1) The deviation should be measured by means of the
prism and cover test with eyes in the mid-line position.
2) The patient should wear the full correction for his
error of refraction.
3) The fixation target should be small.
4) In making the measurements with the eyes looking
upwards and downwards, the extent of the eye
movements should be not more than 25° above and
below the mid-line respectively.
5) The measurements should be made with a fixation
object at a distance of 20 feet.
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15. AETIOLOGY
 The aetiology of vertically incomitant horizontal strabismus has
been argued for years.
 Synthesis of these theories concludes that the most likely
muscles involved are either the horizontal muscles or the
cyclovertical muscles (obliques/vertical rectii) or a combination
of both.
 V pattern: Brown, IO overaction, SO underaction, SR
underaction, LR overaction, Craniofacial anomalies.
 A pattern: SO overaction, IO underaction, LR & IR
underaction.
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16. 1. HORIZONTAL SCHOOL
 This first theory was put forward by URIST.
 He supported the role of horizontal recti,
assuming that lateral recti are more effective
in up-gaze and medial recti are more effective
in downgaze.
 Based on this Urist advocates surgery to correct
the said anomaly ie. In case of overaction of the
rectii, recess(weak) them and in case of 7/15/2020Optom. Ankit varshney16

17. 1) R.E. L.E.
An over action of lateral recti causes V-
exotropia.
(lateral recti are more effective in up-gaze)
It is caused by increase divergence in up gaze.
SR IO
MR
IR SO
SRIO
MR
IRSO
LRLR
EXO ↑ Upgaze
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18. 2) R.E. L.E
An under action of lateral recti causes A -
esotropia.
(lateral recti are more effective in up-
gaze)
It is caused by decreased divergence in up
SR SRIO IO
MRMR LR
IR IRSOSO
LR
Eso ↑ Upgaze
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19. 3) R.E. L.E.
An over action of medial recti causes V-
esotropia
(medial recti are more effective in
downgaze.)
It is caused by increased convergence in
SR IO
MR
IR SO
SRIO
MR
IRSO
LRLR
ESO ↑ Downgaze
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20. 4) R.E. L.E.
An underaction of medial recti causes A -
exotropia.
(medial recti are more effective in
downgaze)
It is caused by decreased convergence in
downward gaze.
SR SRIO IO
MRMRLR LR
IR IRSOSO
Exo ↑ Downgaze
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21. Pattern CAUSED BY
1. V-EXOtropia over action of LR
2. V-ESOtropia over action of MR
3. A-EXOtropia under action of MR
4. A-ESOtropia under action of LR
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22. 2. VERTICAL SCHOOL
 Oblique overaction theory :-
 Here the oblique's are thought to be involved.
 Abduction is a tertiary action of the obliques. Their
overaction is commonly associated with either a
decrease in esodeviation or an increase in
exodeviation in upgaze or downgaze.
*Note:
 With increasing abduction in upgaze, the inferior
obliques are thought to be overacting.
 While increasing abduction in downgaze, the
superior obliques are thought to be overacting. 7/15/2020Optom. Ankit varshney22

23.  This second theory was put forward by BROWN.
 He stressed the role of vertical recti in the etiology
of A-V patterns, the principle being the adducting
property of vertical recti.
 However it seems logical to think that the actions of
vertical recti and oblique muscles are linked
inseparably.
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24. 1) For “A” pattern
(i) “A” phenomenon associated with ESOtropia:- The basic
defect is a weakness UNDERACTION of the INFERIOR
OBLIQUES with a consequent overaction of the superior
recti (the contralateral synergic muscle) causing an
adduction on elevation, and with a consequent overaction
of the superior obliques (the ipsilateral antagonistic
muscles) causing an abduction on depression.
Eso ↑ Upgaze
LR LRMR MR
IO IO
SO SO
SR SR
IR IR
RE LE
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25. (ii) “A” phenomenon associated with EXOtropia:- The basic
defect is a weakness/ UNDERACTION of the inferior RECTI
with consequent over action of the superior recti (the
antagonistic muscles) producing adduction on elevation and
also causes an over action of the superior oblique (the
contralateral synergic muscles) producing abduction on
depression so that the ultimate effects are similar to those
resulting from a weakness of the inferior obliques.
LR LRMR MR
IO IO
SO SO
SR SR
IR IR
RE LE
Exo ↑ Downgaze
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26. 2) For “V” pattern
(i) “V” phenomenon associated with ESOtropia:-
 The basic defect is the weakness / UNDERACTION of the
SUPERIOR OBLIQUES with a consequent over action of the
inferior recti (the contra lateral synergist muscles) causing an
adduction on depression, and with a consequent over action
of inferior oblique (the ipsilateral antagonistic muscles)
causing an abduction of the eyes on elevation.
LR LRMR MR
IO IO
SO SO
SR SR
IR IR
RE LE
ESO ↑ Downgaze
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27. (ii) “V” phenomenon associated with Exotropia:- The
basic defect is weakness/ UNDERACTION of the
SUPERIOR RECTI which causes an over action of the
inferior recti (the ipsilateral antagonistic muscles) which is
responsible for the adduction on depression, and it also
causes an over action of the inferior obliques (the
contralateral synergic muscles) which is responsible for
abduction of the eyes on elevation.
LR LRMR MR
IO IO
SO SO
SR SR
IR IR
RE LE
EXO ↑ Upgaze
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28. PATTERN and OVERACTING MUSCLES
Overacting
muscle
Underacting
muscle
Pattern
caused
IO
IR
SO
SR
V pattern
SO
SR
IO
IR
A pattern
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29. 3) The third theory
It says that they are the result of a combined
abnormality of action of the horizontally and
vertically acting muscles.
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30. Aim
• To detect and measure the pattern
• To determine the reason for pattern if possible
• To asses it significant in the management of strabismus
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31.  Prerequisites;
1. Technique used to measure the deviation in up
gaze and down gaze.
Perfectly this should be done at distance
because at near an over convergence may
be produced in down gaze.
The accommodation should always be
controlled for both distance and near
measurement. Hence the full refractive
correction should be worn.
Otherwise, problems as accommodation and
over convergence at near will produce
spuriously high incidence of V-patterns.
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32. AHP
May adopt to get gid of symptom.
*V eso and A exo chin
depressed .
* V exo and A eso chin elevated
.
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33. • Cover test
• Ocular movement
• Measurement of deviation with
PCT
• Investigation of binocular
function
• Hess chart .
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34. Evaluation:
Measurement - Adults
PBCT * acco.target - 6mts / 33cms
* primary,25˙up & 25˙ down
* moving target /chin up-down
• For A-pattern, there should be at least 10 of
greater esodeviation (or lesser exodeviation)
in up gaze as compared with down gaze.
• For diagnosis of a V-pattern at least 15
greater exodeviation (or lesser esodeviation)
is required in up gaze than in down gaze. 7/15/2020Optom. Ankit varshney34

35. Evaluation:
Measurement - Children
Krimsky’s /Hirschberg’s
Problems;
* lack of cooperation
* short attention span
* incomplete development of following
movement.
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36. Evaluation:
A: Motor * Bino/Uniocular move.9 gazes
* Oblique dysfunction
* Torsion- maddox double rod
B: Sensory * Bagolini’s
- preferred posture
- all 3 vertical gazes
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37. 7/15/2020Optom. Ankit varshney37

39. 7/15/2020Optom. Ankit varshney39

40. 7/15/2020Optom. Ankit varshney40

41. 2) Symptoms and signs
 Patients with A-V patterns are frequently
troubled with intermittent transient diplopia.
 For this reason, they may assume various head
postures.
 Cosmetic problem.
 If the patient has fusion potential, aesthenopia
can be so common symptom.
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42. MANAGEMENT
 The management depends on the clinical factors. If
the pattern is significant and symptomatic,
SURGERY is needed.
All cases of esodeviation or exodeviation should
be checked for A or V pattern. In case of oblique
over action being present, the obliques should be
weakened. In case of under action, the same should
be strengthened.
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43.  TREATMENT
 The current therapy of vertically incomitant
horizontal strabismus is surgical.
Recession:- It is the procedure in which rectus or
oblique muscle is disinserted /removed from its
original position and is reinserted slightly posterior
to the original insertion position.
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44.  Three surgical principles are involved.
These are :-
i. Weakens overacting obliques if either the superior or
inferior obliques are overacting.
ii. If both the superior and inferior obliques are
overacting, weakening of any oblique muscle is
contraindicated.
iii. Vertically transpose the horizontal recti if the oblique
are not overacting.
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45. NO BLANKET FORMULA
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46. Surgical Treatment:
Complications.
* diplopia
* anterior segment ischaemia
* emerging ↑ oblique
* conversion of pattern V → A
* change head posture
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47. ROLE OF AN
OPTOMETRIST
 Pre-operative examination.
 Post-operative checkup.
 Help and maintain to keep B.S.V. if there is B.S.V.
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48.  Thank you
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