For OD students

2. Binocular Balancing
By Kausar Ali 4th semester
Student
Pef University
Doctor of optometry

3. Binocular balancing :
Definition :
The final step in the subjective refraction
is called ‘Binocular balancing ʼ.
Binocular balancing is the is Equalizing
the accommodative effort ʼ ʻ spherical
equalization ʼ
 Aims :
This allow both eyes have the retinal
image simultaneously in focus.

4. An imbalanced correction often leads to
asthenopia because of unstable
accommodation .
Binocular balancing test is not balance
the VA but to balance the state of
accommodation of the two eyes.
The test not only test best sphere but
also be used for checking astigmatic
compound under binocular viewing
condition.
Alternative to binocular balancing tests :

5. 1) cycloplegic Refraction.
2) Binocular Refraction.

6. Criteria:
These techniques are not the
method of choice when
amblyopia is present in one eye .
Deep suppression should not be
present .
There should be BCVA and
essentially almost the same VA
in both eyes .

7. Binocular Balancing
o The final important step of subjective
refraction is to make certain that
accommodation has been relaxed
equally in two eyes .
oSeveral methods of binocular balance
commonly used .
oMost require that the correct visual
acuity be nearly in two eyes .
oFogging and prism dissociation .

8. Fogging:
oWhen the end point refraction is fogged
using +2.0 sphere before each eye.
oThe visual acuity should be reduced to
(6/60 – 6/30) .
oPlace a -0.25 D sphere first before one eye
and then the other and rapidly alternate
cover ,
oThe patient should then be able to identify
the eye with the -0.25 sphere before it has
having the clearer image at 6/30 or 6/20
level.

9. oIf the eyes are not balance, sphere should
be added or subtracted n 0.25 step until
balance is achieved .
oThe fogging method also provides
information regarding appropriate sphere
power .
oEither the eye over minused or under
plussed the patient reads further down the
chart as far as 6/20 , 6/15 or even 6/15 with
the +2.0 fogging spheres in place .
oIn the above case , the refraction end point
should be reconsider .

10. Prism dissociation:
oThe most sensitive test of binocular
balancing is prism dissociation .
oFor this test the refraction end point is
are fogged with +1.00 sphere and
vertical prism of 4 or 5 prism diopters
are placed before one eye .
oThis cause the patient to see 2charts
,one above the other .
oA single line , usually (6/12) is isolated
on the chart .

11. oThe patient seeing 2 separate lines
simultaneously, one for each eye.
oDifference between the fogged image in the
two eyes of as little as 0.25 D spheres are
readily identified .
oIn practice + 0.25 is placed before one eye
and then before other eye .
oIf the eyes are balanced the patient will
report that corresponding to the eye is more
blurred .
oAfter a balance is established between the
two eyes remove prism and reduced the fog
binocularly until maximum VA id obtained .