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 Table of Contents  
CASE REPORT
Year : 2022  |  Volume : 2  |  Issue : 3  |  Page : 729-731

True muscle transplantation in sensory exotropia – A case series


1 Departments of Paediatric Ophthalmology and Strabismus, Vision Eye Centre, New Delhi, India
2 Retina and Uveitis, Vision Eye Centre, New Delhi, India

Date of Submission04-Mar-2022
Date of Acceptance06-May-2022
Date of Web Publication16-Jul-2022

Correspondence Address:
Dr. Smita Kapoor
Department of Paediatric Ophthalmology and Strabismus, Vision Eye Centre, 19 Siri Fort Road, New Delhi - 110 049
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijo.IJO_575_22

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  Abstract 


Management of sensory exotropias is often challenging. In this study, patients who had sensory exotropia >70 prism diopter (PD) were treated with true muscle transplantation. A total of 10 patients with vision <3/60 in one eye were included in the study. All patients underwent transplantation of the medial rectus to the lateral rectus along with a recess–resect procedure. The mean preoperative deviation was 77.5 ± 7.5 PD and postoperative deviation was 6.8 ± 3.2 PD at 1 year. No limitation of movements or lateral incomitance was noted. Thus, this procedure seems to be effective in treating large-angle sensory exodeviations.

Keywords: Sensory exotropia, true muscle transplantation, recession-resection


How to cite this article:
Kapoor S, Grover A. True muscle transplantation in sensory exotropia – A case series. Indian J Ophthalmol Case Rep 2022;2:729-31

How to cite this URL:
Kapoor S, Grover A. True muscle transplantation in sensory exotropia – A case series. Indian J Ophthalmol Case Rep [serial online] 2022 [cited 2022 Aug 13];2:729-31. Available from: https://www.ijoreports.in/text.asp?2022/2/3/729/351202



Management of sensory exotropia is challenging, as patients are reluctant to undergo surgery in the better seeing eye. For large-angle exotropias, bilateral lateral rectus recession has been recommended, leaving the medial recti for a second surgery.[1] To avoid repeat surgeries, three- or four-muscle surgery with adjustable sutures has also been advocated.[2] These procedures are preferred for patients who have good visual acuity in both eyes. However, a unilateral recess–resect procedure in the deviating eye is usually opted for and preferred by the patients with only one seeing eye. Exotropia up to 50 prism diopter (PD) can be corrected by performing two-muscle surgery, but for large-angle exotropia (>70 PD), supramaximal surgery may lead to palpebral fissure width changes and limitation of ductions.[3]

For the above-stated reasons, true muscle transplantation has been studied in large-angle esotropia as well as exotropia,[4],[5],[6] but sufficient data regarding the results of this procedure in sensory deviations is lacking. A recent study with four patients (exotropia and esotropia, two patients each)[7] showed good results for esotropia, but suboptimal results for exotropia. Herein, we report our results with this technique in 10 patients who had sensory exotropia.


  Case Series Top


We analyzed the outcomes of 10 patients who underwent true muscle transplantation at our center from 2018 to 2020. All included patients had best-corrected visual acuity of <3/60 in one eye and >6/9 in the other. Patients with >70 PD exotropia underwent muscle transplantation and were followed up at Day 1, 2 weeks, 1 month, 6 months, and 1 year. Modified Krimsky's test, vertical palpebral fissure height, and extraocular motility were checked at each visit. The surgery was performed using the technique mentioned below.

A fornix incision was made in the inferotemporal quadrant to hook the lateral rectus [Figure 1]a. A 6-0 Prolene suture was applied at the muscle insertion and then it was disinserted [Figure 1]b. Following this, a fornix incision was made in the inferonasal quadrant and medial rectus was hooked [Figure 1]a. Two single-arm 6-0 polyglactin sutures were applied at the muscle insertion and at the desired point, according to the amount of resection needed to be performed [Figure 1]b. Standard resection was done and the resected muscle was transplanted to the lateral rectus [Figure 1]c and [Figure 1]d. The distal end of the medial rectus and the proximal end of the lateral rectus were sutured and recession was performed [Figure 1]d and [Figure 1]e. The temporal and nasal conjunctiva was then closed with 8-0 polyglactin sutures. Fornix incisions were used in eight patients and limbal incisions in two patients because of the presence of preoperative conjunctival scarring. The surgical dosage for recession and resection is mentioned in [Table 1].
Figure 1: (a) Medial and lateral rectus muscles are identified and hooked. (b) Sutures are applied at the lateral and medial rectus stump and at a desired distance according to the amount of resection to be performed. (c) Resected portion of the medial rectus is kept in saline. (d) The distal portion of the resected medial rectus muscle is sutured to the proximal end of the lateral rectus. (e) Lateral rectus is recessed and medial rectus is attached to the original muscle stump

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Table 1: Surgical dosage for transplantation of MR to LR

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The mean age of the 10 patients in whom surgery was performed was 30.6 ± 5.6 years [Table 2]. The mean preoperative angle was 77.5 ± 7.5 PD base in. The mean postoperative angle at 6 months and 1 year follow-up was 5.0 ± 5.0 and 6.8 ± 3.2 PD base in, respectively [Figure 2]. The restriction in adduction was graded between 0 and 4, with 0 being no restriction and 4 being no movement beyond midline. No restriction in abduction was noted at the end of 1 year. No statistical difference was noted between the preoperative (9.8 ± 0.3 mm) and postoperative palpebral fissure vertical height (9.97 ± 0.2 mm) in primary gaze at the end of 1 year postoperatively.
Table 2: Demographic profile of patients

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Figure 2: (a-d) Preoperative and postoperative deviation in primary gaze; (e and f) extraocular motility in extreme gazes

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  Discussion Top


Sensory exotropia is the outward deviation due to longstanding poor vision in one eye. The deviation tends to increase over time due to muscle contracture.[8] The procedure of choice for sensory exotropia is lateral rectus recession and medial rectus resection in the eye with visual loss. But if the deviation is large (>50 PD), a supramaximal recess–resect procedure can be performed. This carries a risk of enophthalmos, palpebral fissure width narrowing, and resistance to abduction if the medial rectus resection is more than 6 mm and reduced abduction if the lateral rectus recession is more than 8 mm.[9] A bilateral three–four muscle surgery may be done, though patients are usually reluctant to be operated in the non-amblyopic eye. Thus, we chose true muscle transplantation in 10 of our patients as the preferred procedure. The effectivity of this procedure[4],[5],[6] has been studied previously and through this case series, we state its benefit in sensory exodeviations.

True muscle transplantation helps to increase the effective length of the muscle that leads to a more potent recession. The chances of rejection of the muscle are none, compared to any other elongating material such as silicon.[4] Since the position of the muscle is still anterior to the equator, there is no limitation of extraocular movement, compared to a supramaximal recession where the new insertion is posterior to the equator. This technique was first described in three patients who had been previously operated for large-angle strabismus. The results obtained were satisfactory during a follow-up of 14 months.[10] Consequently, its role in esotropia was established in many studies,[4],[5],[6],[7] but in exotropia, the outcomes were inferior because of insufficient length of the medial rectus.[7] However, in our study, all the 10 patients showed good postoperative outcomes. This could be attributed to the longer medial rectus stump transplanted by us.


  Conclusion Top


True muscle transplantation is an effective procedure for large-angle sensory exotropia. Along with good postoperative alignment, there is no restriction in ocular movements. Though this study has shown good results up to 1 year, a larger study group and a longer follow-up are required to establish the stability of the procedure.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Jung EH, Kim SJ. Surgical results and factors affecting outcome in adult patients with sensory exotropia. Eye (Lond) 2018;32:1851-7.  Back to cited text no. 1
    
2.
Lau F, Fan D, Yip W, Yu CB, Lam DS. Surgical outcome of single-staged three horizontal muscles squint surgery for extra-large angle exotropia. Eye 2010;24:1171-6.  Back to cited text no. 2
    
3.
Rosenbaum AL, Santiago AP, editors. Clinical Strabismus Management: Principles and Surgical Techniques. Philadelphia: W. B. Saunders; 1999. p. 163-73.  Back to cited text no. 3
    
4.
Jethani JN, Shah N, Amin S, Jethani M. Stability and effects of muscle transplantation for very large angle esotropia. Indian J Ophthalmol 2017;65:607-9.  Back to cited text no. 4
[PUBMED]  [Full text]  
5.
Tibrewal S, Kapoor R, Rath SS, Sachdeva V, Kekunnaya R. Extraocular muscle transplantation for primary treatment of large-angle exotropia. J Binocul Vis Ocul Motil 2021;71:150-60.  Back to cited text no. 5
    
6.
Amitava AK, Goswami AK, Mishra A. Large-angle strabismus and primary true muscle transplantation. J Pediatr Ophthalmol Strabismus 2005;42:211-5.  Back to cited text no. 6
    
7.
Kaur S, Choudhary T, Geh V, Sukhija J. Muscle transplantation for large angle horizontal strabismus. J Pediatr Ophthalmol Strabismus 2020;57:59-62.  Back to cited text no. 7
    
8.
Lajmi H, Ben Yakhlef A, Bouazzeoui EOA, El Fekih L. Outcomes of surgery in patients with sensory exotropia. J Fr Ophtalmol 2020;43:128-32.  Back to cited text no. 8
    
9.
Rayner JW, Jampolsky. Management of adult patients with large angle amblyopic exotropia. Ann Ophthalmol 1973;5:95-9.  Back to cited text no. 9
    
10.
Diamond GR. True transposition procedures. J Pediatr Ophthalmol Strabismus 1990;27:153-6.  Back to cited text no. 10
    


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