- Email: [email protected]
Intraoperative Relaxed Muscle Positioning Technique for Strabismus Repair in Thyroid Eye Disease
Intraoperative Relaxed Muscle Positioning Technique for Strabismus Repair in Thyroid Eye Disease Albert J. Dal Canto, MD, PhD, Sue Crowe, COT, Julian D. Perry, MD, Elias I. Traboulsi, MD Objective: To describe the outcomes of a relaxed muscle technique for treatment of dysthyroid strabismus. Design: Retrospective consecutive case series. Participants: Twenty-four patients with thyroid-related orbitopathy (TRO) underwent strabismus surgery using a novel relaxed muscle technique. Methods: Charts of all patients who underwent rectus muscle recession surgery using a relaxed muscle technique between 1997 and 2004 were reviewed. Twenty-four of 28 patients had more than 2 months of follow-up and were included. The extent of recession was determined by marking where the tendon naturally fell while the relaxed muscle rested freely on the globe with the eye in the primary position. The muscle was sutured to the globe at the mark. Linear regression was used to determine the correlation between the degree of strabismus and the amount of recession required to eliminate diplopia. Main Outcome Measures: Surgical outcomes were analyzed 2 months, 6 months, and 1 year after strabismus repair. Excellent success was defined as no diplopia in primary and reading gazes without prisms. Good outcome was defined as no diplopia in primary and reading positions with the use of ⬍10 prism diopters. Poor outcome was defined as persistent diplopia in primary or reading positions despite prisms, or the inability of the patient to tolerate the necessary prisms. Results: Twenty-four patients underwent 60 muscle recessions. Nine had diplopia without a history of orbital decompression, 8 had diplopia before decompression, and 7 developed diplopia only after orbital decompression. Twenty-one patients (87.5%) had an excellent final outcome. A clinically acceptable (excellent or good) final outcome was achieved in 24 of 24 patients (100%) after an average of 1.08 surgeries. All 7 patients who developed diplopia only after decompression had an excellent outcome. Linear regression did not show good correlation between the degree of strabismus and the amount of recession required to eliminate diplopia (maximum R2 ⫽ 0.7292). There were no complications. Conclusions: The relaxed muscle technique provides excellent ocular alignment and relief from diplopia in a majority of patients with TRO-associated strabismus. Patients who develop diplopia only after orbital decompression may have a higher success rate. Ophthalmology 2006;113:2324 –2330 © 2006 by the American Academy of Ophthalmology.
Thyroid-related orbitopathy (TRO) often produces restrictive strabismus and diplopia from inflammation and fibrosis of the muscles. The disease most commonly involves the inferior and medial recti to cause hypotropia and esotropia, respectively. Bilateral involvement may result in limited upgaze with or without diplopia secondary to inferior rectus restriction. Approximately 4% to 7% of patients with TRO may require surgical intervention to correct strabismus,1,2 and 10% to 70% of patients require strabismus surgery after orbital decompression.3–5 The inflammation-induced fibrosis and thickened extraocular muscles limit the predictability of strabismus surOriginally received: July 15, 2005. Accepted: April 26, 2006. Manuscript no. 2005-657. From Division of Ophthalmology, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio. Correspondence to Elias I. Traboulsi, MD, Division of Ophthalmology, Cole Eye Institute, Desk I-32, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195. E-mail: [email protected].
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gery. Successful fusion in primary and reading positions, even with additional prisms, varies from 38% to 80% using fixed sutures6,7 and from 47% to 81% using adjustable sutures.1,6,8,9 Despite the use of adjustable sutures, 8% to 27% of patients may require ⱖ2 surgeries to eliminate diplopia, even with the use of prisms.1,6,8,9 We sought to determine the efficacy of our technique for determining the extent of muscle recession. The present technique was inspired by Dr Marshall Parks’ general approach to the handling of restrictive strabismus without the use of an adjustable technique. The authors are not aware of an article by Dr Parks on this technique, but the senior author (EIT) clearly recollects this approach in restrictive strabismus during his training with Dr Parks. This is the technique that the senior author always has used. The fixation point for muscle recession is determined intraoperatively after disinsertion by resting the relaxed muscle on the globe in the primary position. It does not depend on preoperative deviation measurements or adjustable sutures. ISSN 0161-6420/06/$–see front matter doi:10.1016/j.ophtha.2006.04.036
Dal Canto et al 䡠 Relaxed Muscle Technique for Strabismus Surgery
Patients and Methods Patients Charts of all patients undergoing a relaxed muscle technique for repair of TRO-associated strabismus performed by one surgeon between 1997 and 2004 were included. Of 44 patients who presented with strabismus, 28 underwent corrective muscle surgery. The relaxed muscle technique described within was used for all cases of TRO-associated strabismus. Twenty-four of the 28 charts had ⬎2 months of follow up and were included in this study. Institutional review board approval was obtained for the chart review. A list of all TRO patients had been maintained based on medical record numbers since 1997. Charts of all patients with TRO-associated strabismus were reviewed, and a separately encoded database was created with the data below, separating the data from patient names and medical record numbers for compliance with the Health Insurance Portability and Accountability Act of 1996. The diagnosis was based on clinical characteristics and history of thyroid abnormalities. Strabismus surgery was performed on patients with stable clinical findings for at least 6 months. Patients who underwent orbital decompression were allowed to stabilize for at least 3 months before undergoing strabismus surgery.
Charts were reviewed for patient gender, age, treatment of TRO, visual acuity, intraocular pressure, manifest refraction, Hertel measurements, results of forced duction testing, deviation in primary gaze, symptoms, relationship of symptoms to orbital decompression, time since orbital decompression, time of clinical stability before strabismus surgery, surgical procedure, extent of muscle recession, length of follow-up, and complications. Exclusion criteria included ⬍2 months of follow-up and previous strabismus surgery. Surgical outcomes were recorded 2 months, 6 months, and 1 year after strabismus repair.
Outcome Analysis Excellent success was defined as no diplopia in primary and reading gazes without prisms. Good outcome was defined as no diplopia in primary and reading positions with the use of ⬍10 prism diopters (⌬). Poor outcome was defined as persistent diplopia in primary or reading positions despite prisms or the inability of the patient to tolerate the necessary prisms. Linear regression was used to determine whether a correlation existed between the degree of strabismus and amount of recession required to eliminate dipolpia. A maximum coefficient of determination (R2) value ⬎ 0.8 is needed to show a strong correlation.
Table 1. Patient Summary Patient Group
Deviation (⌬)
1 2
Post-D ET, 25; A pattern Post-D LET, 35; tight IR
3 4 5
Pre-D ET, 25; A pattern Post-D RET, 30; tight IR Post-D RET, 35
6 7
Post-D ET, 14; tight IR Pre-D ET, 32; tight IR
8 9
Pre-D No-D
16
RHT, 40 LHT, 30; tight IR, right⬎left No-D LHT, 30 No-D LHT, 18 No-D LHT, 22 Post-D RHT, 25 Pre-D RHT, 10; tight RSR No-D ET, 45; RHT, 4; tight IR Pre-D RET, 25; RHT, 18
17 18
No-D ET, 4; LHT, 25 Post-D ET, 12; RHT, 8
19
Pre-D
ET, 30; RHT, 30
20 21
No-D Pre-D
22
No-D
ET, 10; LHT, 30 ET, 25; LHT, 45; tight RIR ET, 6; RHT, 18
23 24
Pre-D No-D
RET, 30; LHT, 12 XT, 10; LHT, 6
10 11 12 13 14 15
Surgical Correction (mm) BMR, 4.0, OU BMR; 7.0, right eye; 6.0, left eye; BIR, 5.0, OU BMR, 4.0, OU BMR; 5.0, OU; BIR, 6.0, OU BMR, 5.0, right eye; 7.0, left eye
Outcome
Further Surgery or Prism
Final Outcome
Orthotropia Orthotropia Orthotropia Orthotropia XT, 6; RHT, 4 BIR: 5, right eye with nasal transplantation 1/2 TW, 4, left eye Orthotropia Orthotropia
BMR; 3.5, OU; BIR, 4.0, OU BMR: 5, right eye; 6, left eye; BIR, 5.0, OU RSR, 6.0, right eye; LIR, 7.0, left eye BIR, 9.0, right eye, 7.0, left eye
Orthotropia Orthotropia
RIR, 7.0, right eye RIR, 4.0, right eye RIR, 5.0, right eye LIR, 6.0, left eye RSR, 3.5, right eye BMR, 5.5, OU
Orthotropia RHT, 4 Orthotropia Orthotropia Orthotropia ET, 8; RHT, 8
BMR: 4.0, right eye; 4.5, left eye; BIR: 5.0, right eye; 6.0, left eye RMR, 3.5, right eye; RIR, 5.0, right eye BMR: 4.0, right eye, 3.0, left eye; BIR: 4.0, right eye, 6.0, left eye BMR: 4.0, right eye, 5.0, left eye; LIR, 8.0, left eye RMR, 6.0, right eye; RIR, 7.0, right eye RMR, 6.0, right eye; RIR, 8.0, right eye; LSR, 4.0, left eye LMR, 5.0, left eye; RIR, 3.5, right eye; LIR, 6.0, left eye LMR, 7.0, left eye; RIR, 6.0, right eye RLR, 4.0, right eye; RIR, 4.0, right eye
RHT, 14
Orthotropia
Prism, 5 ⌬ BD, right eye
Orthotropia
Prism: 8 ⌬ BO, left eye, 8 ⌬ BD, right eye LMR, ⬃7.5 total; LIR, ⬃9.0 total
Orthotropia ET, 6, ¡ orthotropia with 4 ⌬ BO
Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia
BD ⫽ base down prism; BIR ⫽ bilateral inferior rectus recession; BMR ⫽ bilateral medial rectus recession; BO ⫽ base out prism; ⌬ ⫽ prism diopters; ET ⫽ esotropia; HT ⫽ hypertropia; IR ⫽ inferior rectus; LHT ⫽ left hypertropia; LIR ⫽ left inferior rectus recession; LMR ⫽ left medial rectus recession; no-D ⫽ diplopia, no decompression; OU ⫽ both eyes; post-D ⫽ diplopia only after decompression; pre-D ⫽ diplopia preceding decompression; RET ⫽ right esotropia; RHT ⫽ right hypertropia; RIR ⫽ right inferior rectus recession; RLR ⫽ right lateral rectus recession; RMR ⫽ right medial rectus recession; RSR ⫽ right superior rectus recession; SR ⫽ superior rectus; TW ⫽ tendon width; XT ⫽ exotropia.
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Ophthalmology Volume 113, Number 12, December 2006 Table 2. Final Outcome after Strabismus Surgery with Respect to Orbital Decompression Groups Group
Average No. of Extraocular Muscles Operated On*
n
P Value†
% Excellent
n
P Value‡
% Excellent ⴙ Good
n
P Value‡
Post-D No-D Pre-D
3.0 1.8 2.6
7 9 8
0.025 — 0.038
100.0 77.8 87.5
7 9 8
— 0.08 0.18
100.0 100.0 100.0
7 9 8
— 0.50 0.50
No-D ⫽ diplopia, no decompression; post-D ⫽ diplopia only after decompression; pre-D ⫽ diplopia preceding decompression. *Per patient (sum of both eyes) at initial surgery. † Compared with no-D group. ‡ Compared with post-D group.
Surgical Technique All strabismus surgeries were performed under general anesthesia with muscle relaxation by one surgeon (EIT) using the same relaxed muscle technique. Intraoperative forced ductions were performed to confirm which muscles required recession. A fornixbased incision was used to expose the muscle insertion. Intermuscular attachments and check ligaments were severed using Westcott scissors, with care to lyse the capsulopalpebral ligaments during inferior rectus recession. The distal rectus tendon was isolated with muscle hooks and secured with a double-armed 6-0 polyglactin 910 suture in double-locking fashion. The tendon was separated from the globe using the Westcott scissors, and forced ductions were repeated to confirm free ocular movement. The point of reattachment was selected by allowing the muscle to rest freely on the globe with the globe positioned such that the
anteroposterior axis was perpendicular to the frontal plane. The location where the edge of the tendon met the globe was marked with a marking pen. The distance from the original muscle insertion was measured with calipers or a ruler. The tendon was then sutured at the mark using a crossed-swords technique. The conjunctiva was reapproximated with interrupted 6-0 polyglactin 910 suture. No more than 2 ipsilateral muscle recessions were performed simultaneously.
Results Twenty-four patients underwent strabismus surgery for TRO using the relaxed muscle technique presented herein. There were 19 females and 5 males. Mean age was 50.2 years (range, 20 –71). Four patients underwent bilateral medial rectus recession, 1 un-
Figure 1. Outcome after strabismus surgery. Hashed bars show outcomes after one initial surgery, and solid bars show final outcomes after a maximum of 2 surgeries. Both patients with a poor outcome after one surgery improved after a second surgery. Results are shown for each decompression group and for all patients combined. No-D ⫽ diplopia, no decompression; post-D ⫽ diplopia only after decompression; pre-D ⫽ diplopia preceding decompression. *P ⫽ 0.09 compared with no-D, and P ⫽ 0.04 compared with no-D ⫹ pre-D.
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Dal Canto et al 䡠 Relaxed Muscle Technique for Strabismus Surgery
Figure 2. Total medial rectus (MR) recession versus preoperative esotropia (ET) for all patients. There are 2 patients represented by the point at 8-mm recession with 25–prism diopter (⌬) ET. The solid line represents the best-fit linear regression and the associated coefficient of determination (R2). Note that the correlation is not strong (⬍0.8). The dashed line represents the amount of recession that would be specified by a standard surgical nomogram. *Undercorrection (2) or overcorrection (1). Data from Wright KW, ed. Color Atlas of Ophthalmic Surgery: Strabismus. Philadelphia: Lippincott; 1991:241–2.
derwent bilateral inferior rectus recession, 4 underwent unilateral inferior rectus recession, 6 underwent both bilateral medial rectus and bilateral inferior rectus recessions, and 5 underwent other combinations of inferior rectus and medial rectus recessions. One patient underwent a right superior rectus recession and left inferior rectus recession; 1 underwent only a right superior rectus recession; 1 underwent recessions of the right medial rectus, right inferior rectus, and left superior rectus; and 1 underwent a right lateral rectus recession and right inferior rectus recession. Diplopia occurred without a history of orbital decompresssion in 9 patients, preceded decompression in 8 patients, and followed decompression in 7 patients. Seven patients had isolated esotropia (mean, 28 ⌬), 7 had isolated hypertropia (mean, 25 ⌬), 9 had a combination of esotropia and hypertropia (mean: esotropia, 21 ⌬; hypertropia, 21 ⌬), and 1 had a combination of exotropia and hypertropia (exotropia, 10 ⌬; hypertropia, 6 ⌬). Preoperative measurements were stable for an average of 11.8 months (range, 3–36). Table 1 describes the number and laterality of each case. Patients underwent an average of 2.4 extraocular muscle recessions (1.5 per eye) during the first surgery. Patients who underwent prior orbital decompression required an average of 3.0 extraocular muscle recessions during the first surgery. Patients without a history of decompression required statistically fewer muscle recessions (average, 1.8; P ⫽ 0.025) (Table 2). After a single surgery, only 2 of 24 patients (8.3% overall) had a poor outcome. One patient had developed diplopia only after orbital decompression, and the other patient had a history of diplopia preceding decompression. Both of these patients underwent a second surgery; 1 had an excellent final result and 1 had a good final result. Figure 1 shows outcomes after one surgery as well as final outcomes for each decompression group. Overall, after a single surgery 20 of 24 patients (83.3%) had an excellent
outcome, 2 of 24 (8.3%) had a good outcome, and 2 of 24 (8.3%) had a poor outcome. After a maximum of 2 surgeries, 21 of 24 patients (87.5%) had an excellent outcome, 3 (12.5%) had a good outcome, and no patient remained with a poor outcome (Fig 1). No patient required a third surgery. The reoperation rate was 8%, with a mean of 1.08 surgeries per patient. There was no statistical significance in the reoperation rate between patients without decompression (0/9 patients) and those who developed diplopia only after orbital decompression (1/7 patients). Average follow-up was 5.9 months (range, 2–12). Thirteen patients had follow-up of at least 6 months, and all showed stable alignment before 6 months and afterwards. No patient demonstrating orthotropia at the 2-month follow-up visit complained of diplopia at later follow-up visits. No patient developed complications from this technique that we are aware of. Linear regression did not show a good correlation between the angle of strabismus and amount of rectus muscle recession required. For all patients with esotropia or esotropia and hypertropia (n ⫽ 16), R2 was 0.7292 for the total amount of medial rectus recession plotted against preoperative deviation (Fig 2). For the subset of patients with an excellent outcome (n ⫽ 13), R2 ⫽ 0.6985. There was no correlation when the difference between the total recession performed and a standard nomogram was plotted as a function of preoperative deviation (Fig 3). Of 8 patients undergoing bilateral inferior rectus recession, 12 of 16 eyes required recessions of ⱖ5 mm. As with medial rectus recessions, the amount of inferior rectus recession for bilateral cases did not significantly correlate with the preoperative angle of strabismus (R2 ⫽ 0.448) (Fig 4). The R2 value for unilateral vertical rectus recessions resulting in orthotropia was 0.5583 (n ⫽ 7) (not shown). Four patients underwent bilateral inferior
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Figure 3. Difference between the total medial rectus (MR) recession performed and the amount that would be specified by a standard surgical nomogram as a function of preoperative esotropia (ET). There are 2 patients represented by the point at 0 mm with 25–prism diopter (⌬) ET. A positive y-value shows that a larger recession was performed than would be indicated by the nomogram; a negative value represents the converse. The solid line represents the best-fit linear regression. The associated coefficient of determination (R2) shows a poor correlation. *Undercorrection (2) or overcorrection (1). Nomogram from Wright KW, ed. Color Atlas of Ophthalmic Surgery: Strabismus. Philadelphia: Lippincott; 1991:241–2.
rectus recession in the absence of preoperative vertical strabismus to improve ocular position and upgaze.
Discussion Thyroid-related orbitopathy–associated strabismus often results in significant difficulty with daily activities and a decreased quality of life. Eye muscle surgery may restore orthotropia, relieve diplopia, and dramatically improve function. The underlying muscle and orbital fibrosis poses special surgical challenges. Prior orbital decompression may complicate these surgeries further by precipitating or exacerbating strabismus. Nomograms for the pediatric population to determine the extent of muscle recession may not apply to patients with TRO-associated strabismus. Bilateral inferior rectus restriction causing limited upgaze without diplopia also poses challenges regarding determination of the extent of muscle recession. To improve surgical outcomes, many surgeons advocate the use of adjustable sutures. Reports show excellent results in 47% to 81% of patients and acceptable results in 73% to 91% of patients using adjustable sutures.1,6,8,9 Adjustable suture techniques carry the morbidity of postoperative manipulation, and reoperation rates vary from 8% to 27%.1,6,8,9 We achieved an excellent final outcome in 87.5% of patients and a clinically acceptable outcome in 100% of patients without the need for adjustment. Our reoperation rate was 8%. We were unable to find any descriptions of a similar technique for TRO-associated strabismus via Medline searches.
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Patients with a history of diplopia only after decompression had a higher rate of an excellent outcome than did patients who developed diplopia independently of orbital decompression (P ⫽ 0.04). Patients without diplopia before decompression may have less severe extraocular muscle disease and normal muscle contractility, allowing for better surgical results. Although more muscles required surgery in patients who had undergone decompression, these patients did not require more reoperations than patients who did not have previous orbital decompression. Our data do not appear to fit in a nomogram. Linear regression did not show a strong correlation between the amount of recession and degree of preoperative strabismus. The number of patients was relatively small, limiting the power of regression analysis. However, the inability to develop a nomogram is why many authors advocate using adjustable sutures and why we have developed the technique presented here. As is evident in Figures 2 to 4, the difference between the amount recessed and a typical nomogram is independent of the degree of preoperative strabismus. The lack of correlation between preoperative measurement and the amount of recession may be due to altered extraocular muscle dynamics secondary to fibrosis. Our technique allows for the recession amount to vary with the degree of muscle fibrosis, independent of ocular deviation measurements, thus eliminating the need for nomograms. This may be especially helpful in cases of symmetrical inferior rectus restriction with minimal or no preoperative diplopia. Four patients underwent bilateral inferior rectus recessions in the absence of preoperative vertical diplopia. These cases may have otherwise re-
Dal Canto et al 䡠 Relaxed Muscle Technique for Strabismus Surgery
Figure 4. Total vertical rectus recession (bilateral surgery) versus preoperative vertical deviation (hypertropia [HT]). There are 2 patients represented by the point at 10-mm recession with 0 –prism diopter (⌬) HT. The solid line represents the best-fit linear regression and the associated coefficient of determination (R2). The dashed line represents the amount of recession specified by a standard surgical nomogram. Data from Wright KW, ed. Color Atlas of Ophthalmic Surgery: Strabismus. Philadelphia: Lippincott; 1991:241–2.
sulted in undercorrection using standard techniques. Inferior rectus recession is important in these cases to improve patient function in primary gaze and upgaze. Large bilateral inferior rectus recessions were common in this series and resulted in excellent postoperative outcomes. These large recessions did not limit infraduction, but patients often required further surgery to address resultant lower eyelid retraction. Our study is limited by its retrospective nature and the relatively small number of patients. However, it was a consecutive case series in which all patients underwent an identical technique. No TRO patients underwent strabismus surgery with adjustable sutures or any other technique besides the intraoperative relaxed muscle technique. As a result, there was no case selection bias towards this technique versus another in our series. However, we cannot compare the results of our technique directly with those of any other method. Although 11 patients had ⬍6 months of follow-up, the 2-month visit was an excellent predictor for long-term results in the remaining 13 patients. Previous results support that intermediate-term measurements typically remain stable.6,10 The small number of patients included in each of the nomograms limits the power of the regression analysis. However, our goal with this analysis was not to create a new nomogram, but rather to show that our data are consistent with the consensus in the field that stra-
bismus surgery for TRO is difficult because nomograms do not fit well. Many have resorted to adjustable sutures to circumvent this problem. Our solution is the relaxed muscle technique presented here. There were no complications seen with our technique, although the ability to detect adverse events is limited by the small number of patients. Our novel technique of intraoperative relaxed muscle positioning for TRO-associated strabismus surgery allows for excellent results, with a low reoperation rate. It obviates the need for postoperative manipulation and can be used for patients with or without a history of orbital decompression.
References 1. Lueder GT, Scott WE, Kutschke PJ, Keech RV. Long-term results of adjustable suture surgery for strabismus secondary to thyroid ophthalmopathy. Ophthalmology 1992;99: 993–7. 2. Inoue Y, Tsuboi T, Kouzaki A, et al. Ophthalmic surgery in dysthyroid ophthalmopathy. Thyroid 2002;12:257– 63. 3. Goldberg RA, Perry JD, Hortaleza V, Tong JT. Strabismus after balanced medial plus lateral wall versus lateral wall only orbital decompression for dysthyroid orbitopathy. Ophthal Plast Reconstr Surg 2000;16:271–7. 4. Garrity JA, Fatourechi V, Bergstralh EJ, et al. Results of
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Ophthalmology Volume 113, Number 12, December 2006 transantral orbital decompression in 428 patients with severe Grave’s ophthalmopathy. Am J Ophthalmol 1993;116:533– 47. 5. Warren JD, Spector JG, Burde R. Long-term follow-up and recent observations on 305 cases of orbital decompression for dysthyroid orbitopathy. Laryngoscope 1989;99: 35– 40. 6. Kraus DJ, Bullock JD. Treatment of thyroid ocular myopathy with adjustable and nonadjustable suture strabismus surgery. Trans Am Ophthalmol Soc 1993;91:67–79.
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7. Evans D, Kennerdell JS. Extraocular muscle surgery for dysthyroid myopathy. Am J Ophthalmol 1983;95:767–71. 8. Fells P, Kousoulides L, Pappa A, et al. Extraocular muscle problems in thyroid eye disease. Eye 1994;8:497–505. 9. Flanders M, Hastings M. Diagnosis and surgical management of strabismus associated with thyroid-related orbitopathy. J Pediatr Ophthalmol Strabismus 1997;34:333– 40. 10. Keech RV, Scott WE, Christensen LE. Adjustable suture strabismus surgery. J Pediatr Ophthalmol Strabismus 1987; 24:97–102.
Thyroid-related orbitopathy (TRO) often produces restrictive strabismus and diplopia from inflammation and fibrosis of the muscles. The disease most commonly involves the inferior and medial recti to cause hypotropia and esotropia, respectively. Bilateral involvement may result in limited upgaze with or without diplopia secondary to inferior rectus restriction. Approximately 4% to 7% of patients with TRO may require surgical intervention to correct strabismus,1,2 and 10% to 70% of patients require strabismus surgery after orbital decompression.3–5 The inflammation-induced fibrosis and thickened extraocular muscles limit the predictability of strabismus surOriginally received: July 15, 2005. Accepted: April 26, 2006. Manuscript no. 2005-657. From Division of Ophthalmology, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio. Correspondence to Elias I. Traboulsi, MD, Division of Ophthalmology, Cole Eye Institute, Desk I-32, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195. E-mail: [email protected].
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© 2006 by the American Academy of Ophthalmology Published by Elsevier Inc.
gery. Successful fusion in primary and reading positions, even with additional prisms, varies from 38% to 80% using fixed sutures6,7 and from 47% to 81% using adjustable sutures.1,6,8,9 Despite the use of adjustable sutures, 8% to 27% of patients may require ⱖ2 surgeries to eliminate diplopia, even with the use of prisms.1,6,8,9 We sought to determine the efficacy of our technique for determining the extent of muscle recession. The present technique was inspired by Dr Marshall Parks’ general approach to the handling of restrictive strabismus without the use of an adjustable technique. The authors are not aware of an article by Dr Parks on this technique, but the senior author (EIT) clearly recollects this approach in restrictive strabismus during his training with Dr Parks. This is the technique that the senior author always has used. The fixation point for muscle recession is determined intraoperatively after disinsertion by resting the relaxed muscle on the globe in the primary position. It does not depend on preoperative deviation measurements or adjustable sutures. ISSN 0161-6420/06/$–see front matter doi:10.1016/j.ophtha.2006.04.036
Dal Canto et al 䡠 Relaxed Muscle Technique for Strabismus Surgery
Patients and Methods Patients Charts of all patients undergoing a relaxed muscle technique for repair of TRO-associated strabismus performed by one surgeon between 1997 and 2004 were included. Of 44 patients who presented with strabismus, 28 underwent corrective muscle surgery. The relaxed muscle technique described within was used for all cases of TRO-associated strabismus. Twenty-four of the 28 charts had ⬎2 months of follow up and were included in this study. Institutional review board approval was obtained for the chart review. A list of all TRO patients had been maintained based on medical record numbers since 1997. Charts of all patients with TRO-associated strabismus were reviewed, and a separately encoded database was created with the data below, separating the data from patient names and medical record numbers for compliance with the Health Insurance Portability and Accountability Act of 1996. The diagnosis was based on clinical characteristics and history of thyroid abnormalities. Strabismus surgery was performed on patients with stable clinical findings for at least 6 months. Patients who underwent orbital decompression were allowed to stabilize for at least 3 months before undergoing strabismus surgery.
Charts were reviewed for patient gender, age, treatment of TRO, visual acuity, intraocular pressure, manifest refraction, Hertel measurements, results of forced duction testing, deviation in primary gaze, symptoms, relationship of symptoms to orbital decompression, time since orbital decompression, time of clinical stability before strabismus surgery, surgical procedure, extent of muscle recession, length of follow-up, and complications. Exclusion criteria included ⬍2 months of follow-up and previous strabismus surgery. Surgical outcomes were recorded 2 months, 6 months, and 1 year after strabismus repair.
Outcome Analysis Excellent success was defined as no diplopia in primary and reading gazes without prisms. Good outcome was defined as no diplopia in primary and reading positions with the use of ⬍10 prism diopters (⌬). Poor outcome was defined as persistent diplopia in primary or reading positions despite prisms or the inability of the patient to tolerate the necessary prisms. Linear regression was used to determine whether a correlation existed between the degree of strabismus and amount of recession required to eliminate dipolpia. A maximum coefficient of determination (R2) value ⬎ 0.8 is needed to show a strong correlation.
Table 1. Patient Summary Patient Group
Deviation (⌬)
1 2
Post-D ET, 25; A pattern Post-D LET, 35; tight IR
3 4 5
Pre-D ET, 25; A pattern Post-D RET, 30; tight IR Post-D RET, 35
6 7
Post-D ET, 14; tight IR Pre-D ET, 32; tight IR
8 9
Pre-D No-D
16
RHT, 40 LHT, 30; tight IR, right⬎left No-D LHT, 30 No-D LHT, 18 No-D LHT, 22 Post-D RHT, 25 Pre-D RHT, 10; tight RSR No-D ET, 45; RHT, 4; tight IR Pre-D RET, 25; RHT, 18
17 18
No-D ET, 4; LHT, 25 Post-D ET, 12; RHT, 8
19
Pre-D
ET, 30; RHT, 30
20 21
No-D Pre-D
22
No-D
ET, 10; LHT, 30 ET, 25; LHT, 45; tight RIR ET, 6; RHT, 18
23 24
Pre-D No-D
RET, 30; LHT, 12 XT, 10; LHT, 6
10 11 12 13 14 15
Surgical Correction (mm) BMR, 4.0, OU BMR; 7.0, right eye; 6.0, left eye; BIR, 5.0, OU BMR, 4.0, OU BMR; 5.0, OU; BIR, 6.0, OU BMR, 5.0, right eye; 7.0, left eye
Outcome
Further Surgery or Prism
Final Outcome
Orthotropia Orthotropia Orthotropia Orthotropia XT, 6; RHT, 4 BIR: 5, right eye with nasal transplantation 1/2 TW, 4, left eye Orthotropia Orthotropia
BMR; 3.5, OU; BIR, 4.0, OU BMR: 5, right eye; 6, left eye; BIR, 5.0, OU RSR, 6.0, right eye; LIR, 7.0, left eye BIR, 9.0, right eye, 7.0, left eye
Orthotropia Orthotropia
RIR, 7.0, right eye RIR, 4.0, right eye RIR, 5.0, right eye LIR, 6.0, left eye RSR, 3.5, right eye BMR, 5.5, OU
Orthotropia RHT, 4 Orthotropia Orthotropia Orthotropia ET, 8; RHT, 8
BMR: 4.0, right eye; 4.5, left eye; BIR: 5.0, right eye; 6.0, left eye RMR, 3.5, right eye; RIR, 5.0, right eye BMR: 4.0, right eye, 3.0, left eye; BIR: 4.0, right eye, 6.0, left eye BMR: 4.0, right eye, 5.0, left eye; LIR, 8.0, left eye RMR, 6.0, right eye; RIR, 7.0, right eye RMR, 6.0, right eye; RIR, 8.0, right eye; LSR, 4.0, left eye LMR, 5.0, left eye; RIR, 3.5, right eye; LIR, 6.0, left eye LMR, 7.0, left eye; RIR, 6.0, right eye RLR, 4.0, right eye; RIR, 4.0, right eye
RHT, 14
Orthotropia
Prism, 5 ⌬ BD, right eye
Orthotropia
Prism: 8 ⌬ BO, left eye, 8 ⌬ BD, right eye LMR, ⬃7.5 total; LIR, ⬃9.0 total
Orthotropia ET, 6, ¡ orthotropia with 4 ⌬ BO
Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia Orthotropia
BD ⫽ base down prism; BIR ⫽ bilateral inferior rectus recession; BMR ⫽ bilateral medial rectus recession; BO ⫽ base out prism; ⌬ ⫽ prism diopters; ET ⫽ esotropia; HT ⫽ hypertropia; IR ⫽ inferior rectus; LHT ⫽ left hypertropia; LIR ⫽ left inferior rectus recession; LMR ⫽ left medial rectus recession; no-D ⫽ diplopia, no decompression; OU ⫽ both eyes; post-D ⫽ diplopia only after decompression; pre-D ⫽ diplopia preceding decompression; RET ⫽ right esotropia; RHT ⫽ right hypertropia; RIR ⫽ right inferior rectus recession; RLR ⫽ right lateral rectus recession; RMR ⫽ right medial rectus recession; RSR ⫽ right superior rectus recession; SR ⫽ superior rectus; TW ⫽ tendon width; XT ⫽ exotropia.
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Ophthalmology Volume 113, Number 12, December 2006 Table 2. Final Outcome after Strabismus Surgery with Respect to Orbital Decompression Groups Group
Average No. of Extraocular Muscles Operated On*
n
P Value†
% Excellent
n
P Value‡
% Excellent ⴙ Good
n
P Value‡
Post-D No-D Pre-D
3.0 1.8 2.6
7 9 8
0.025 — 0.038
100.0 77.8 87.5
7 9 8
— 0.08 0.18
100.0 100.0 100.0
7 9 8
— 0.50 0.50
No-D ⫽ diplopia, no decompression; post-D ⫽ diplopia only after decompression; pre-D ⫽ diplopia preceding decompression. *Per patient (sum of both eyes) at initial surgery. † Compared with no-D group. ‡ Compared with post-D group.
Surgical Technique All strabismus surgeries were performed under general anesthesia with muscle relaxation by one surgeon (EIT) using the same relaxed muscle technique. Intraoperative forced ductions were performed to confirm which muscles required recession. A fornixbased incision was used to expose the muscle insertion. Intermuscular attachments and check ligaments were severed using Westcott scissors, with care to lyse the capsulopalpebral ligaments during inferior rectus recession. The distal rectus tendon was isolated with muscle hooks and secured with a double-armed 6-0 polyglactin 910 suture in double-locking fashion. The tendon was separated from the globe using the Westcott scissors, and forced ductions were repeated to confirm free ocular movement. The point of reattachment was selected by allowing the muscle to rest freely on the globe with the globe positioned such that the
anteroposterior axis was perpendicular to the frontal plane. The location where the edge of the tendon met the globe was marked with a marking pen. The distance from the original muscle insertion was measured with calipers or a ruler. The tendon was then sutured at the mark using a crossed-swords technique. The conjunctiva was reapproximated with interrupted 6-0 polyglactin 910 suture. No more than 2 ipsilateral muscle recessions were performed simultaneously.
Results Twenty-four patients underwent strabismus surgery for TRO using the relaxed muscle technique presented herein. There were 19 females and 5 males. Mean age was 50.2 years (range, 20 –71). Four patients underwent bilateral medial rectus recession, 1 un-
Figure 1. Outcome after strabismus surgery. Hashed bars show outcomes after one initial surgery, and solid bars show final outcomes after a maximum of 2 surgeries. Both patients with a poor outcome after one surgery improved after a second surgery. Results are shown for each decompression group and for all patients combined. No-D ⫽ diplopia, no decompression; post-D ⫽ diplopia only after decompression; pre-D ⫽ diplopia preceding decompression. *P ⫽ 0.09 compared with no-D, and P ⫽ 0.04 compared with no-D ⫹ pre-D.
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Dal Canto et al 䡠 Relaxed Muscle Technique for Strabismus Surgery
Figure 2. Total medial rectus (MR) recession versus preoperative esotropia (ET) for all patients. There are 2 patients represented by the point at 8-mm recession with 25–prism diopter (⌬) ET. The solid line represents the best-fit linear regression and the associated coefficient of determination (R2). Note that the correlation is not strong (⬍0.8). The dashed line represents the amount of recession that would be specified by a standard surgical nomogram. *Undercorrection (2) or overcorrection (1). Data from Wright KW, ed. Color Atlas of Ophthalmic Surgery: Strabismus. Philadelphia: Lippincott; 1991:241–2.
derwent bilateral inferior rectus recession, 4 underwent unilateral inferior rectus recession, 6 underwent both bilateral medial rectus and bilateral inferior rectus recessions, and 5 underwent other combinations of inferior rectus and medial rectus recessions. One patient underwent a right superior rectus recession and left inferior rectus recession; 1 underwent only a right superior rectus recession; 1 underwent recessions of the right medial rectus, right inferior rectus, and left superior rectus; and 1 underwent a right lateral rectus recession and right inferior rectus recession. Diplopia occurred without a history of orbital decompresssion in 9 patients, preceded decompression in 8 patients, and followed decompression in 7 patients. Seven patients had isolated esotropia (mean, 28 ⌬), 7 had isolated hypertropia (mean, 25 ⌬), 9 had a combination of esotropia and hypertropia (mean: esotropia, 21 ⌬; hypertropia, 21 ⌬), and 1 had a combination of exotropia and hypertropia (exotropia, 10 ⌬; hypertropia, 6 ⌬). Preoperative measurements were stable for an average of 11.8 months (range, 3–36). Table 1 describes the number and laterality of each case. Patients underwent an average of 2.4 extraocular muscle recessions (1.5 per eye) during the first surgery. Patients who underwent prior orbital decompression required an average of 3.0 extraocular muscle recessions during the first surgery. Patients without a history of decompression required statistically fewer muscle recessions (average, 1.8; P ⫽ 0.025) (Table 2). After a single surgery, only 2 of 24 patients (8.3% overall) had a poor outcome. One patient had developed diplopia only after orbital decompression, and the other patient had a history of diplopia preceding decompression. Both of these patients underwent a second surgery; 1 had an excellent final result and 1 had a good final result. Figure 1 shows outcomes after one surgery as well as final outcomes for each decompression group. Overall, after a single surgery 20 of 24 patients (83.3%) had an excellent
outcome, 2 of 24 (8.3%) had a good outcome, and 2 of 24 (8.3%) had a poor outcome. After a maximum of 2 surgeries, 21 of 24 patients (87.5%) had an excellent outcome, 3 (12.5%) had a good outcome, and no patient remained with a poor outcome (Fig 1). No patient required a third surgery. The reoperation rate was 8%, with a mean of 1.08 surgeries per patient. There was no statistical significance in the reoperation rate between patients without decompression (0/9 patients) and those who developed diplopia only after orbital decompression (1/7 patients). Average follow-up was 5.9 months (range, 2–12). Thirteen patients had follow-up of at least 6 months, and all showed stable alignment before 6 months and afterwards. No patient demonstrating orthotropia at the 2-month follow-up visit complained of diplopia at later follow-up visits. No patient developed complications from this technique that we are aware of. Linear regression did not show a good correlation between the angle of strabismus and amount of rectus muscle recession required. For all patients with esotropia or esotropia and hypertropia (n ⫽ 16), R2 was 0.7292 for the total amount of medial rectus recession plotted against preoperative deviation (Fig 2). For the subset of patients with an excellent outcome (n ⫽ 13), R2 ⫽ 0.6985. There was no correlation when the difference between the total recession performed and a standard nomogram was plotted as a function of preoperative deviation (Fig 3). Of 8 patients undergoing bilateral inferior rectus recession, 12 of 16 eyes required recessions of ⱖ5 mm. As with medial rectus recessions, the amount of inferior rectus recession for bilateral cases did not significantly correlate with the preoperative angle of strabismus (R2 ⫽ 0.448) (Fig 4). The R2 value for unilateral vertical rectus recessions resulting in orthotropia was 0.5583 (n ⫽ 7) (not shown). Four patients underwent bilateral inferior
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Figure 3. Difference between the total medial rectus (MR) recession performed and the amount that would be specified by a standard surgical nomogram as a function of preoperative esotropia (ET). There are 2 patients represented by the point at 0 mm with 25–prism diopter (⌬) ET. A positive y-value shows that a larger recession was performed than would be indicated by the nomogram; a negative value represents the converse. The solid line represents the best-fit linear regression. The associated coefficient of determination (R2) shows a poor correlation. *Undercorrection (2) or overcorrection (1). Nomogram from Wright KW, ed. Color Atlas of Ophthalmic Surgery: Strabismus. Philadelphia: Lippincott; 1991:241–2.
rectus recession in the absence of preoperative vertical strabismus to improve ocular position and upgaze.
Discussion Thyroid-related orbitopathy–associated strabismus often results in significant difficulty with daily activities and a decreased quality of life. Eye muscle surgery may restore orthotropia, relieve diplopia, and dramatically improve function. The underlying muscle and orbital fibrosis poses special surgical challenges. Prior orbital decompression may complicate these surgeries further by precipitating or exacerbating strabismus. Nomograms for the pediatric population to determine the extent of muscle recession may not apply to patients with TRO-associated strabismus. Bilateral inferior rectus restriction causing limited upgaze without diplopia also poses challenges regarding determination of the extent of muscle recession. To improve surgical outcomes, many surgeons advocate the use of adjustable sutures. Reports show excellent results in 47% to 81% of patients and acceptable results in 73% to 91% of patients using adjustable sutures.1,6,8,9 Adjustable suture techniques carry the morbidity of postoperative manipulation, and reoperation rates vary from 8% to 27%.1,6,8,9 We achieved an excellent final outcome in 87.5% of patients and a clinically acceptable outcome in 100% of patients without the need for adjustment. Our reoperation rate was 8%. We were unable to find any descriptions of a similar technique for TRO-associated strabismus via Medline searches.
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Patients with a history of diplopia only after decompression had a higher rate of an excellent outcome than did patients who developed diplopia independently of orbital decompression (P ⫽ 0.04). Patients without diplopia before decompression may have less severe extraocular muscle disease and normal muscle contractility, allowing for better surgical results. Although more muscles required surgery in patients who had undergone decompression, these patients did not require more reoperations than patients who did not have previous orbital decompression. Our data do not appear to fit in a nomogram. Linear regression did not show a strong correlation between the amount of recession and degree of preoperative strabismus. The number of patients was relatively small, limiting the power of regression analysis. However, the inability to develop a nomogram is why many authors advocate using adjustable sutures and why we have developed the technique presented here. As is evident in Figures 2 to 4, the difference between the amount recessed and a typical nomogram is independent of the degree of preoperative strabismus. The lack of correlation between preoperative measurement and the amount of recession may be due to altered extraocular muscle dynamics secondary to fibrosis. Our technique allows for the recession amount to vary with the degree of muscle fibrosis, independent of ocular deviation measurements, thus eliminating the need for nomograms. This may be especially helpful in cases of symmetrical inferior rectus restriction with minimal or no preoperative diplopia. Four patients underwent bilateral inferior rectus recessions in the absence of preoperative vertical diplopia. These cases may have otherwise re-
Dal Canto et al 䡠 Relaxed Muscle Technique for Strabismus Surgery
Figure 4. Total vertical rectus recession (bilateral surgery) versus preoperative vertical deviation (hypertropia [HT]). There are 2 patients represented by the point at 10-mm recession with 0 –prism diopter (⌬) HT. The solid line represents the best-fit linear regression and the associated coefficient of determination (R2). The dashed line represents the amount of recession specified by a standard surgical nomogram. Data from Wright KW, ed. Color Atlas of Ophthalmic Surgery: Strabismus. Philadelphia: Lippincott; 1991:241–2.
sulted in undercorrection using standard techniques. Inferior rectus recession is important in these cases to improve patient function in primary gaze and upgaze. Large bilateral inferior rectus recessions were common in this series and resulted in excellent postoperative outcomes. These large recessions did not limit infraduction, but patients often required further surgery to address resultant lower eyelid retraction. Our study is limited by its retrospective nature and the relatively small number of patients. However, it was a consecutive case series in which all patients underwent an identical technique. No TRO patients underwent strabismus surgery with adjustable sutures or any other technique besides the intraoperative relaxed muscle technique. As a result, there was no case selection bias towards this technique versus another in our series. However, we cannot compare the results of our technique directly with those of any other method. Although 11 patients had ⬍6 months of follow-up, the 2-month visit was an excellent predictor for long-term results in the remaining 13 patients. Previous results support that intermediate-term measurements typically remain stable.6,10 The small number of patients included in each of the nomograms limits the power of the regression analysis. However, our goal with this analysis was not to create a new nomogram, but rather to show that our data are consistent with the consensus in the field that stra-
bismus surgery for TRO is difficult because nomograms do not fit well. Many have resorted to adjustable sutures to circumvent this problem. Our solution is the relaxed muscle technique presented here. There were no complications seen with our technique, although the ability to detect adverse events is limited by the small number of patients. Our novel technique of intraoperative relaxed muscle positioning for TRO-associated strabismus surgery allows for excellent results, with a low reoperation rate. It obviates the need for postoperative manipulation and can be used for patients with or without a history of orbital decompression.
References 1. Lueder GT, Scott WE, Kutschke PJ, Keech RV. Long-term results of adjustable suture surgery for strabismus secondary to thyroid ophthalmopathy. Ophthalmology 1992;99: 993–7. 2. Inoue Y, Tsuboi T, Kouzaki A, et al. Ophthalmic surgery in dysthyroid ophthalmopathy. Thyroid 2002;12:257– 63. 3. Goldberg RA, Perry JD, Hortaleza V, Tong JT. Strabismus after balanced medial plus lateral wall versus lateral wall only orbital decompression for dysthyroid orbitopathy. Ophthal Plast Reconstr Surg 2000;16:271–7. 4. Garrity JA, Fatourechi V, Bergstralh EJ, et al. Results of
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Ophthalmology Volume 113, Number 12, December 2006 transantral orbital decompression in 428 patients with severe Grave’s ophthalmopathy. Am J Ophthalmol 1993;116:533– 47. 5. Warren JD, Spector JG, Burde R. Long-term follow-up and recent observations on 305 cases of orbital decompression for dysthyroid orbitopathy. Laryngoscope 1989;99: 35– 40. 6. Kraus DJ, Bullock JD. Treatment of thyroid ocular myopathy with adjustable and nonadjustable suture strabismus surgery. Trans Am Ophthalmol Soc 1993;91:67–79.
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7. Evans D, Kennerdell JS. Extraocular muscle surgery for dysthyroid myopathy. Am J Ophthalmol 1983;95:767–71. 8. Fells P, Kousoulides L, Pappa A, et al. Extraocular muscle problems in thyroid eye disease. Eye 1994;8:497–505. 9. Flanders M, Hastings M. Diagnosis and surgical management of strabismus associated with thyroid-related orbitopathy. J Pediatr Ophthalmol Strabismus 1997;34:333– 40. 10. Keech RV, Scott WE, Christensen LE. Adjustable suture strabismus surgery. J Pediatr Ophthalmol Strabismus 1987; 24:97–102.