Do spectacles alter all squints: Dr. Madhu Karna Strabismologist

High hyperopia with Accomodative Esotropia with Consecutive Exotropia

1. Do Spectacles alter all squints?
Dr. Madhu Karna
Strabismologist

2. Accomodative esotropia

3. Infantile esotropia after surgery

4. Hyperopia & Congenital esotropia
Frequency Degree Management
Habitual Mild Earlier surgery
Occasional Significant(>3.5D)Early surgery
contraindicated
PostoperativeEventual increaseSecondary Et that
improves with
optical Rx

5. This squint may trap you by
seeming simple but
HYPEROPIA WITH EXOTROPIA

6. Before you operate this patient
Just remove the
glasses

7. Esotropia without glasses !!

8. What is it?

High hyperopia with Accomodative
Esotropia with Consecutive ExotropiaExotropia

9. High hyperopia with Accomodative
Esotropia with Consecutive Exotropia
Reduce hyperopic power by half
If exotropia still manifest or there is a
drop in visual acuity then operate on
the consecutive Exotropia after
measuring over maximum cyclopegic
refraction.

10. What do you do when you see this
kind of a patient?
EXOTROPIA
HIGH MYOPIA

11. ESOTROPIA

HIGH HYPEROPIA
Or one like this

12. Do you measure with prism over glasses and
operate on the measured angle?
A hyperopic patient of +10.00 ref
error measured to have 50 pd of
esotropia over glasses.
He was operated for 50 pd to achieve
ortho
but was undercorrected
with residual eso of 15-20pd

13. We really don’t learn anything from
our experience we only learn from
reflecting on our experience.

14. ARTIFACTS INTRODUCED BY SPECTACLE
LENSES IN THE MEASUREMENT OF
STRABISMIC DEVIATIONS
KIRK D. SCATTERGOOD , M H
BROWN,D L GUYTON
AJO 96:439-448,1983
The peripheral prismatic effect of
corrective spectacles introduce an
artifact when measuring strabismus

15. The peripheral prismatic effect of corrective spectacles introduce
an artifact when measuring strabismus
c
θt∆t
h
11.5 13.5
25
D
∆m
[ ∆t ][ ∆t ] x 100 = x 100 = 100 100 %%
[ ∆m ] 1- 0.025 D[ ∆m ] 1- 0.025 D
Simplified model

16. In clinical practice it is the
measured deviation that is
found first and true deviation
must then be calculated

17. In clinical practice it is the measured deviation
that is found first and true deviation must then
be calculated

18. Calculating the true deviation
If glasses are plus
Measured deviation = True deviation – 2.5 D%
[D-lens power]
If glasses are minus
Measured deviation = True deviation + 2.5 D%
In clinical practice it is the measured deviation that is found
first and true deviation must then be calculated .
Using the simplified model the authors obtain an expression
for true deviation [∆t]
as a percentage of measured deviation [∆m]
[ ∆t ] x 100 = 100 %
[ ∆m ] 1- 0.025 D

19. Plus lenses decrease and minus lenes
increase the measured deviation.
Spectacle lens
power
True deviation
as %of
measured
deviation
To find true deviation
Change
measured
deviation by Example
-20 67 Decrease by
33%
4/6
-10 80 Decrease by
20%
4/5
PLANO 100 No change 4/4
+10 133 Increase by
33%
4/3
+20 200 Increase
by100%
4/2

20. High Plus lenses in both exo & eso –
M D <T D [undercor]
High Minus lenses in both exo & eso
– M D >T D [overcor]
This becomes Sx significant with
refractive errors of + 5 d
This formula deals with strabismus
measurements with distance fixation

21. If you have built castles in the air, your
work need not be lost, that is where they
should be, now put the foundations under
them.

22. If you have not measured with C L,
with this formula you can still achieve orthophoria
Myope of 10D with measured deviation-
exo of 40 pd was operated for the
true deviation 32pd (20% less) which
gave good alignment
-10D MYOPE WITH EXOTROPIA
POSTOPERATIVE
MEASURED DEVIATION 40PD PREOP

23. Take home message
Plus lenses decrease
&
Minus lenses increase

the measured deviation

24. Fortune favors the prepared mind

25. THANK YOU