The final step of subjective refraction is binocular balancing, which equalizes the accommodative effort between the two eyes. This allows for both retinal images to come into focus simultaneously. An imbalanced correction can cause asthenopia due to unstable accommodation. Several binocular balancing tests are commonly used, including fogging and prism dissociation. Fogging involves alternately placing -0.25D spheres before each eye while the patient identifies the clearer image at 6/30 or 6/20. Prism dissociation uses vertical prisms and fogging to have the patient view two separate lines, identifying the more blurred image to establish balancing between the eyes.

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 .