Differential diagnosis of Dissociated vertical deviation

1. Differential diagnosis
Of DVD

2. Diagnosis of DVD
▪ Easier to see when patient fixates a distance target (greater
at distance )
▪ Either eye elevates when fellow eye is fixating.
▪ Elevation is followed by extorsion and refixation is followed
by intorsion.
▪ The vertical angle of dissociated deviation is somewhat less
in abduction than in adduction.
▪ Latent nystagmus occurs in approximately half the patients
with DVD.

3. Contd…
▪ It is often found in association with infantile esotropia and
less often with accommodative acquired esotropia,
exotropia and heterotropia of sensory origin.
▪ Head tilt towards fixating eye.
▪ Likely to develop poor BSV.

4. DVD Vs overaction of IO
▪ In DVD covered eye becomes elevated in abduction,
primary position and adduction.
Conversly, with the overaction of IO muscles each eye
becomes elevated primarily in adduction but never in
abduction unless there is coexisting contracture of ipsilateral
SR muscle.

5. Contd…
▪ When a patient with overacting IO muscle fixates with
involved eye in field of action (elevation and adduction)
the contralateral SR will under act.
▪ Conversely in patients with DVD who are tested in same
manner under action of contralateral yoke muscle
doesn’t occur.

6. Contd..
▪ Refixation movement in overaction of IO is rapid- 20 to
400°/s
▪ Refixation movement is slow in DVD- 10 to 200°/s
▪ Tonic incycloduction in IO overaction when takes refixation
is so rapid that it cannot be appreciated. While, in DVD
excyclotorsion on elevation and on refixation intorsion can
easily be observed.

7. Contd…
▪ Both A and V patterns can be seen in DVD, however A
pattern are more common and this can differentiate DVD
from IO over action where V pattern would be expected.
▪ Latent nystagmus is usually present in DVD but absent in IO
over action
▪ Belchowsky darkening wedge test is positive in DVD and
negetive in IO over action.

8. Belchowsky darkening wedge test
▪ The principle is to gradually reduce the amount of light
entering the eye.
▪ A graded wedge was originally used but a neutral filter density
bar is preferred nowadays.
▪ The patient fixates a light and the non fixating eye is occluded,
hence the eye behind the occluder will elevate.
.

9. ▪ As the density of neutral filter is gradually increased before the
fixating eye, the eye under cover will be seen to move down
possibly below the midline
▪ As the filter density is reduced the eye under cover will
progressively elevate again.

10. DVD associated with comitant
cyclovertical anomalies.
▪ When associated with comitant or paretic cyclovertical
anomalies the diagnosis of DVD is more difficult.
▪ When evaluating such patients one must take into account
the starting position of each eye before the cover is applied.
▪ For instance, if a right hypertropia is associated with a DVD,
the right eye will become further elevated under the cover
▪ And the fellow left hypo tropic eye will move upward the
same amount but may only reach the midline, since it began
its movement from depressed position.

11. Red glass test
▪ Red glass yields peculiar result in DVD.
▪ Regardless of whether the red filter is placed before the right or
left eye the patient describes a red image below a white image.
▪ This contrasts with patients with a true vertical deviation.
▪ In true hypertropia the second (red) image is seen above or
below the primary image depending on whether the red filter is
place before hypo or hyper deviated eyes.

12. DVD and SO overaction
▪ The SO muscles formerly were implicated as a possible cause of
DVD. However the report of A pattern exotropia, SO overaction
and DVD made this hypothesis unpopular.
▪ Recent studies have resurrected this theory based on the fact
that the eye elevates and undergoes excyclotorsion in DVD.
▪ A hypo functioning SO muscle could explain both findings.

13. Management
▪ The initial management consideration for a patient with DVD is
the prognosis for establishing normal binocular vision.
▪ If the prognosis for establishing BSV is good , the management
strategy is based on the characteristics of associated horizontal
strabismus.
▪ If the prognosis is poor, the treatment is directed towards
addressing concerns about cosmesis.

14. The sequential strategy
▪ Its general treatment strategy is to avoid those viewing
conditions that produce temporary abnormal innervations
▪ And to enhance those conditions that prevents the
manifestation of DVD

15. The sequential strategy
1. Prescribe the appropriate lens correction for far and near
2. Determine the dissociated horizontal and vertical deviations
at far and at near. (Note which eye has larger hyperdeviations)
3. Prescribe associated viewing Active Vision Therapy to
establish peripheral sensory fusion without vertical prism or
prism target separation.(Avoid dissociation and darkening of
eyes)

16. 4. Prescribe minimum vertical prism resulting in stable sensory
fusion if primary component.
5. Prescribe AVT to improve motor fusion range. Note vertical
need for sensory fusion if primary component is present.
6. Prescribe the vertical prism or the most frequently
encountered vertical prisms that results in stable central sensory
fusion at the orthoposition.

17. Prism Therapy
▪ Prisms should not be given until such time that a primary
component is identified
▪ Measuring the objective angle under associated viewing
conditions (eg. Major amblyoscope) can give more reliable
results.

18. Occlusion Therapy
▪ Occlusion may be needed to eliminate sensory anomalies
such as suppression, amblyopia and AC.
▪ Note- Covering one eye may result in larger and more
varialble hyperdeviations when patch is removed.

19. Active vision therapy
▪ In orthoptic procedures for constant strabismus DVDs are best
approached by first ignoring the vertical condition
▪ Anti suppression procedures are prescribed with the goals to
achieve normal sensory fusion.
▪ Some DVD patient progress to efficient binocular vision
showing no vertical deviation when associated .
▪ While some may show an accompanying primary vertical
requiring prism therapy to maintain efficient binocular fusion.

20. Case presentation
▪ A 7 yrs old girl presented with fair cosmesis.
History:
The parents were concerned about her school performance.
They complained of an eye turn inward and outward were
present at times.
Onset was unknown, but thought it was from infancy. No
previous exam.

21. ▪ Refractive status
Cycloplegic RE +3.00-1.00*180 20/20
LE +3.00-1.00*180 20/20
Deviation
With correction a constant BET of 10Pd with LE preferred for
fixation.Verticals were estimated to be 12 pd right hyper(RH) and 8
pd left hyper (LH).DVD increased in size with prolonged occlusion.

22. ▪ Associated condition
▪ No amblyopia and steady fixation RE and LE. Intermittent
suppression and sensory fusion of peripheral targets and
constant suppression of central or foveal targets at
distance. Normal correspondence andno stereopsis with or
without BO or vertical prism.
▪ Plan
Rx RE +2.00-1.oo*180 5BO
LE +2.00-1.00*180 5BO

23. Vision therapy
-Stereoscope with large peripheral targets.
- Blinking and pointing to break suppression
- Sensorimotor stimulation at distance and vectograms
(vertical prisms added if needed).
- Tritated BO prisms prisms as fusional divergence increased.

24. ▪ Results:
▪ Suppression lessened and sensory fusion was stabilized
with AVT.
▪ Efficient binocular viewing at all conditions

25. Surgery
▪ Surgical procedures preferred by various authors are
1. Recession of superior combined with resection of inferior rectus
muscle.
2. Resection of inferior recti
3. Retroequatorial myopexy ( posterior fixation ) of superior recti
combined with or without a recession of these muscles.
4. Unconventionally large recessions(5 to 10 mm) of superior recti.
5. Anterior displacement of inferior oblique insertion which may be
combined with superior rectus recession.

26. Summary
▪ The overaction of IO may look like DVD or vice verca. So
meticulous
observation or other tests (if required) are performed to make
the diagnosis.
▪ DVD should not be chased with vertical prisms.
▪ The key is to establish normal sensory fusion first .
▪ After sensory fusion occurs the presence of primary vertical
component either comitant or non comitant is often clearly
evidenced.