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

1. Strategies for residual / consecutive / recurrent Esodeviations

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 2012

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

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 2012

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 2012

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’ 2003, @ pp 257-9 Kowal Hyderabad 2012

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 2012

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

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 2012

‘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 2012

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 2012

Some rare reasons Sphenoid sinusitis Ditropan medication for enuresis Oxybutynin-associated esotropia Wong, Harding & Kowal J AAPOS 2007;11:624-625. Kowal Hyderabad 2012

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

Table 1 : Botox in Esotropia Sahare, Kowal, Marshman N PRE INJ POST INJ %CHANGE Residual 7 26 ∆ 5 ∆ 59 Consec 6 32 9 74 Large 5 64 22 66 Cong 1 80 0 100 with surgery Kowal Hyderabad 2012

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

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 - 11.5mm 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 2012

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 - 11.5mm 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

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 2012

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 40 -15 = 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 2012

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 2012

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 2012

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

Table 1 : Esotropia Residual 7 26 ∆ 5 ∆ 59 Consec 6 32 9 74 N PRE INJ POST INJ %CHANGE Residual 7 26 ∆ 5 ∆ 59 Consec 6 32 9 74 Large 5 64 22 66 Cong 1 80 0 100 with surgery Kowal Hyderabad 2012

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 25y [50% followup] Kowal Hyderabad 2012

50% of patients: 2ND & 3RD decades after last ET surgery KOWAL personal series MEDIAN TIME TO SURGERY 22 YRS. AVERAGE 23. Kowal Hyderabad 2012

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 2012 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.

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 1-612 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 2012

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 ∆

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 2012

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 2012

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 40 - 15 = 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 2012

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