Strategies for reoperations in consecutive recurrent strabismus Start
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
1. Strategies for residual / consecutive / recurrent Esodeviations
Residual / Recurrent ET : WHY? #1 Reason: Underplussed or otherwise accommodative. Simple office test: pilocarpine 2% stat OU Check cyclo refraction again Kowal Hyderabad 2012 3
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 2012 4
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 ≥ 1 mm even though the surgeon knew the photo was going to be reviewed ± 1 mm can have 5 -10Δ effect / muscle Uncertainty of scar formation Kowal Hyderabad 2012 5
Recurrent ET after recess/resect Consider slipped LR. LK : a. Bduction deficit not apparent for >12 mo Re-presented like ‘acute 6 th’ , presumably having suddenly exceeded motor fusional reserve ? Detect with 50 MHz UBM? Kraft successful; Kowal not reliable Kowal Hyderabad 2012 6
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’: 9 th meeting of the International Strabismological Association’ 2003, @ pp 257 -9 Kowal Hyderabad 2012 7
Residual : WHY? Range BMR for 15 – 50 Δ: surgical tables very reliable. Expectation 2 nd surgery ~10% in Y 1 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 2012 8
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 2012 Most of the patients presented outside normal age range for strabismus 9
Residual : WHY? Range BMR for 15 – 50 Δ: surgical tables very reliable. Expectation 2 nd surgery ~10% in Y 1 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 2012 10
‘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 22 mm ± 10% >24. 2 mm: augment recession dose by 10% >26. 4 mm: … by 20% Kowal Hyderabad 2012 11
ET of Myopic Strabismus Fixus – have to do the correct operation 181. 1 deg. SR SR 103. 6 deg. LR LR Preoperative . Kowal Hyderabad 2012 From Yokoyama Postoperative 12
Some rare reasons Sphenoid sinusitis Ditropan medication for enuresis Oxybutynin-associated esotropia Wong, Harding & Kowal J AAPOS 2007; 11: 624 -625. Kowal Hyderabad 2012 13
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 2012 14
Botox in Esotropia Sahare, Kowal, Marshman Table 1 : n N PRE INJ POST INJ %CHANGE n n Residual 7 26 ∆ 59 n Consec 6 32 9 74 n Large 5 64 22 66 n Cong 1 80 0 100 with surgery Kowal Hyderabad 2012 15
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 2012 16
Principles of residual ET surgery 2. Previous BMR: FDT. If MR tight: plan to recess a little more Explore each MR. If MR already @ 11 - 11. 5 mm from limbus, don’t recess more – will result in consecutive XT [whereas MR Botox won’t] LR resect OU: deduct 0. 5 mm per muscle from usual tables Difficult / unpredictable. Use adjustables. If too young, improve the springback test Kowal Hyderabad 2012 17
Principles of residual ET surgery 3. After Recess – Resect FDT. If MR tight: plan to recess a little more Explore each MR. If MR already @ 11 - 11. 5 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 2012 18
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. 5 mm from limbus If I want an extras 25Δ effect = 12. 5Δ from each of 2 muscles. Kowal Hyderabad 2012 19
Re-recessing the MR – guidelines to get me started Let us say I find the MR 8. 5 mm from limbus = 3 mm recess = ‘A’ BMR 3 is for ET 15Δ. BMR 5. 5 is for ET 40Δ. The difference is 40 -15 = 25Δ = 12. 5Δ x 2. Each MR if moved from 3 mm 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. 5 mm and a 2 nd muscle for a 12. 5Δ effect I will get the 25Δ effect I need Kowal Hyderabad 2012 20 FROM KEN WRIGHT’S BOOK
Consecutive ET Simple – not worrying: Small angle, intermittent, week 1 after 1 st 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 2012 21
Valenzuela, A CLADE 2000 134 pts operated intermittent XT. Follow up >3 y! 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 2012 22
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 2012 23
Table 1 : n Esotropia N PRE INJ POST INJ %CHANGE n n Residual 7 26 ∆ 59 n Consec 6 32 9 74 n Large 5 64 22 66 n Cong 1 80 0 100 with surgery Kowal Hyderabad 2012 24
2. Strategies for consecutive / recurrent Exodeviations
HOW COMMON IS CONSEC XT? Alberto Ciancia [Argentina]: 90% perfect early alignment after cong ET surgery [n=390] 30% consec XT over next 25 y [50% followup] Kowal Hyderabad 2012 26
ND RD 2 &3 50% of patients: decades after last ET surgery KOWAL personal series MEDIAN TIME TO SURGERY 22 YRS. 27 Kowal Hyderabad 2012 AVERAGE 23.
Scar remodeling after strabismus surgery Irene Ludwig, MD, Alan Chow, MD “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” Kowal Hyderabad 2012 28 JAAPOS 4: 326 -333; 2000
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%] Ø Mean time between original strabismus surgery and scar repair 122 mo (range 1 -612 mo). [LK series: 307 mo] Ø Median age at time of repair 19 y (range 3 -68 y) [LK series: 33 y, range 3 -68 y !]. Kowal Hyderabad 2012 29
These are difficult cases Need to make MR function normal or XT will recur Ø Difficult to dissect out tendons Ø Muscle ‘meat’ can be 20+ mm from limbus Ø Try to use Mersilene or other non-absorbable Ø Keep Mersilene knot >8 -9 mm from limbus Ø Adjustables often necessary Ø Fat may be present Ø NO surgical tables Ø Intra-op ‘spring back’ as a guide Ø Guide: Early ET ≥ 10 ∆ 30
SUMMARY - CONSEC XT Ø Common in a dedicated strabismus practice Ø Common in a cong ET population Ø Expect 2/3 to do very well Ø 10% do not do well Kowal Hyderabad 2012 31
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 9 mm from the original insertion If I want an extra 25Δ effect = 12. 5Δ from each of 2 muscles. Kowal Hyderabad 2012 32
Re-recessing the LR – guidelines to get me started Let us say I find the LR 4 mm from insertion = ‘A’ LR Rc 4 mm OU is for XT 15Δ. Rc 8 mm is for XT 40Δ. The difference is 40 - 15 = 25Δ = 12. 5Δ x 2. Each LR if moved from 4 mm 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 4 mm and a 2 nd muscle for a 12. 5Δ effect I will get the 25Δ effect I need Kowal Hyderabad 2012 FROM KEN WRIGHT’S BOOK 33
Thank You Yarra River footbridge Melbourne Australia Kowal Hyderabad 2012 34
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