1. Fusion LVPEI Hyderabad 2012 Lionel Kowal Melbourne, Australia
Strategies for re-operations in consecutive / recurrent strabismus Start off with humility : it is much easier than having it thrust on you
Fusion LVPEI Hyderabad 2012
Lionel Kowal
Melbourne, Australia

2. 1. Strategies for residual / consecutive / recurrent Esodeviations

3. Residual / Recurrent ET : WHY
Residual / Recurrent ET : WHY? #1 Reason: Underplussed or otherwise accommodative.
Simple office test: pilocarpine 2% stat OU
Check cyclo refraction again
Kowal Hyderabad

4. Residual : WHY? Other less common reasons
Range BMR for 15 – 50 Δ: surgical tables very reliable, but not 100% ‘bell curve’.
R-R: has the LR slipped?
Is there an orbital problem : occult Graves’
Is there a supranuclear problem: Chiari
Is the globe unusually big: ‘simple’ myopia OR ‘myopic strabismus fixus’
Kowal Hyderabad

5. Does the muscle always end up where you plan to put it?
PAT in ET study in late 1980’s. All recessions were photographed with caliper
25 % were under- / over- recessed by ≥ 1mm even though the surgeon knew the photo was going to be reviewed
±1mm can have 5-10Δ effect / muscle
Uncertainty of scar formation
Kowal Hyderabad

6. Recurrent ET after recess/resect
Consider slipped LR.
LK : aBduction deficit not apparent for >12 mo
Re-presented like ‘acute 6th’ , presumably having suddenly exceeded motor fusional reserve
? Detect with 50 MHz UBM?
Kraft successful; Kowal not reliable
Kowal Hyderabad

7. Occult Graves’ Rare in childhood / adolescence
Uncommon cause of poor surgical result in ET in adolescents
ENLARGED MUSCLE STRABISMUS
Kowal et alii in ‘Progress in Strabismology’: 9th meeting of the International Strabismological Association’ pp 257-9
Kowal Hyderabad

8. Residual : WHY? Is there a supranuclear problem: Chiari
Range BMR for 15 – 50 Δ: surgical tables very reliable. Expectation 2nd surgery ~10% in Y1
R-R: has the LR slipped?
Is there an orbital problem : occult Graves’
Is there a supranuclear problem: Chiari
Is the globe unusually big: ‘simple’ myopia OR ‘myopic strabismus fixus’
Kowal Hyderabad

9. Chiari: age at presentation of strabismus Kowal L, Yahalom C, Shuey NH Chiari 1 malformation presenting as strabismus BVQ 2006; 21:18-26
Kowal Hyderabad
Most of the patients presented outside normal age range for strabismus

10. Residual : WHY?
Range BMR for 15 – 50 Δ: surgical tables very reliable. Expectation 2nd surgery ~10% in Y1
R-R: has the LR slipped?
Is there an orbital problem : occult Graves’
Is there a supranuclear problem: Chiari
Is the globe unusually big: ‘simple’ myopia OR ‘myopic strabismus fixus’
Kowal Hyderabad

11. ‘Simple myopia’ - Modify surgical dose for axial length
Data is ? inconclusive / supportive - in the eye of the reader
Large globe = larger circumference
Need larger recession to achieve same angular effect as on a small globe
LK: normal globe 22mm ± 10%
>24.2 mm: augment recession dose by 10%
>26.4 mm: … by 20%
Kowal Hyderabad

12. ET of Myopic Strabismus Fixus – have to do the correct operation
Preoperative
181.1 deg. LR SR
Postoperative
103.6 deg. LR SR .
From Yokoyama
Kowal Hyderabad

13. Some rare reasons Sphenoid sinusitis Ditropan medication for enuresis
Oxybutynin-associated esotropia Wong, Harding & Kowal J AAPOS 2007;11:
Kowal Hyderabad

14. Treatment of Residual / Recurrent ET: What to do now?
1. Push +
2. MR Botox:
very good for ~20 Δ residual ET
3. Reoperate
Kowal Hyderabad

15. Table 1 : Botox in Esotropia Sahare, Kowal, Marshman
N PRE INJ POST INJ %CHANGE
Residual ∆ ∆
Consec
Large
Cong
with surgery
Kowal
Hyderabad

16. Principles of residual ET surgery Reoperation 1
If there’s a problem [e.g. slipped LR] you must fix it
Difficult / unpredictable. Use adjustables.
Kowal Hyderabad

17. Principles of residual ET surgery 2. Previous BMR:
FDT. If MR tight: plan to recess a little more
Explore each MR. If MR mm from limbus, don’t recess more – will result in consecutive XT [whereas MR Botox won’t]
LR resect OU: deduct 0.5mm per muscle from usual tables
Difficult / unpredictable. Use adjustables. If too young, improve the springback test
Kowal Hyderabad

18. Principles of residual ET surgery 3. After Recess – Resect
FDT. If MR tight: plan to recess a little more
Explore each MR. If MR mm from limbus, don’t recess more – will result in consecutive XT [whereas Botox won’t]
R-R other eye is usually the most predictable operation
Difficult / unpredictable. Use adjustables.
Kowal Hyderabad

19. Re-recessing the MR – guidelines to get me started
Let us say I have a pt with residual or recurrent ET of 25Δ.
On a normal globe, it is safe to recess to 6.5mm from limbus
If I want an extras 25Δ effect = 12.5Δ from each of 2 muscles.
Kowal Hyderabad

20. Re-recessing the MR – guidelines to get me started
Let us say I find the MR 8.5mm from limbus = 3mm recess = ‘A’
BMR 3 is for ET 15Δ. BMR 5.5 is for ET 40Δ.
The difference is = 25Δ = 12.5Δ x 2.
Each MR if moved from 3mm recess to 5.5 mm recess can be expected to have a 12.5Δ effect.
So I can expect that when I move an MR from ‘A’ a distance of 2.5mm and a 2nd muscle for a 12.5Δ effect I will get the 25Δ effect I need
FROM KEN WRIGHT’S BOOK
Kowal Hyderabad

21. Consecutive ET Simple – not worrying:
Small angle, intermittent, week 1 after 1st XT surgery, not bothersome to patient
Of Greater Concern:
Larger angle [esp ≥20Δ] , ≥2 previous surgeries, some incomitance, bothersome to patient
Of Very Great concern:
≥25Δ in week 1 [esp. >30] , not improving quickly
Kowal Hyderabad

22. Valenzuela, A CLADE 2000
134 pts operated intermittent XT. Follow up >3y!
If initial alignment between 5Δ XT & 20Δ ET: 90% ended up small phorias, E [≤5Δ] or X [≤10Δ]
No difference in subgroups in this range [0-5Δ XT had same outcome as 15-20Δ ET]
≥15Δ XT: all had poor result
5 pts 25-30Δ ET: 3 ended up OK
Exodrift continued for ~12 mo
Kowal Hyderabad

23. If not getting better…….
LK preferred technique: MR botox
UK: ~ 50% success in delayed group
Repeat surgery - usually explore muscles and undo some of the surgery
Kowal Hyderabad

24. Table 1 : Esotropia Residual 7 26 ∆ 5 ∆ 59 Consec 6 32 9 74
N PRE INJ POST INJ %CHANGE
Residual ∆ ∆
Consec
Large
Cong
with surgery
Kowal Hyderabad

25. 2. Strategies for consecutive / recurrent Exodeviations

26. HOW COMMON IS CONSEC XT?
Alberto Ciancia [Argentina]: 90% perfect early alignment after cong ET surgery [n=390]  30% consec XT over next 25y [50% followup]
Kowal Hyderabad

27. 50% of patients: 2ND & 3RD decades after last ET surgery
KOWAL
personal series
MEDIAN TIME TO SURGERY 22 YRS. AVERAGE 23.
Kowal Hyderabad

28. Scar remodeling after strabismus surgery Irene Ludwig, MD, Alan  Chow, MD JAAPOS 4: 326-333; 2000
“When we explored the … muscles of patients with such overcorrections, the expectation was that the muscles would be found normally healed at their original surgical attachment sites and that repositioning ….would repair the deviations. … many of the overcorrection cases demonstrated a segment of amorphous scar tissue separating the tendon from its attachment site on the sclera”
Relative to all reoperation cases, lengthened scars were estimated to be found in about 10%, and in the subset of patients with late overcorrections, in about 50%.
Kowal Hyderabad
When we explored the previously operated muscles of patients with such overcorrections, the expectation was that the muscles would be found normally healed at their original surgical attachment sites and that repositioning of the insertions would repair the deviations. We found, however, that many of the overcorrection cases demonstrated a segment of amorphous scar tissue separating the tendon from its attachment site on the sclera
The mean time between the original strabismus surgery and the scar repair was 122 months (range, 1 to 612 months). The median age of the patients at the time of repair was 18.8 years (range, 3.1 to 67.8 years).
Forty-three patients with lengthened scars were able to date the onset of recurrent strabismus, some by recollection and some with medical record documentation. Twenty-one of the cases developed within 4 months of surgery (probable early stretching), and 20 developed after 18 months (probable late stretching), one as long after as 516 months.
The time course of the development of strabismus overcorrection was gradual in most cases, and overcorrection was not seen in any patients immediately after surgery, as would be expected with an improperly attached muscle. Stretched scar segments were frequently bilateral and symmetrical, which would be unlikely in a true slipped muscle case. The cases of documented restretching in spite of repair with firm reattachment of tendon to sclera also support the contention that a lengthened scar is different from a slipped muscle. Scar segments were shorter than the long capsule described with slipped muscles. Dense connective tissue consistent with scar tissue was documented histologically in these cases, as opposed to the capsule of a slipped muscle, which would show loose connective tissue.

29. Scar remodeling after strabismus surgery
 Relative to all reoperation cases, lengthened scars were estimated to be found … in the subset of patients with late overcorrections, in about 50% [LK series: 42%]
Mean time between original strabismus surgery and scar repair 122 mo (range mo). [LK series: 307 mo]
Median age at time of repair 19 y (range 3-68 y) [LK series: 33 y, range 3-68y !].
Kowal Hyderabad

30. These are difficult cases
Need to make MR function normal or XT will recur
Difficult to dissect out tendons
Muscle ‘meat’ can be 20+ mm from limbus
Try to use Mersilene or other non-absorbable
Keep Mersilene knot >8-9mm from limbus
Adjustables often necessary
Fat may be present
NO surgical tables
Intra-op ‘spring back’ as a guide
Guide: Early ET ≥ 10 ∆

31. SUMMARY - CONSEC XT Common in a dedicated strabismus practice
Common in a cong ET population
Expect 2/3 to do very well
10% do not do well
Kowal Hyderabad

32. Re-recessing the LR – guidelines to get me started
Let us say I have a pt with residual or recurrent XT of 25Δ.
On a normal globe, it is reliable to recess LR to 9mm from the original insertion
If I want an extra 25Δ effect = 12.5Δ from each of 2 muscles.
Kowal Hyderabad

33. Re-recessing the LR – guidelines to get me started
Let us say I find the LR 4mm from insertion = ‘A’
LR Rc 4mm OU is for XT 15Δ. Rc 8 mm is for XT 40Δ.
The difference is = 25Δ = 12.5Δ x 2.
Each LR if moved from 4mm recess to 8 mm recess can be expected to have a 12.5Δ effect.
So I can expect that when I move a LR from ‘A’ a distance of 4mm and a 2nd muscle for a 12.5Δ effect I will get the 25Δ effect I need
FROM KEN WRIGHT’S BOOK
Kowal Hyderabad

34. Thank You Yarra River footbridge Melbourne Australia
Kowal Hyderabad