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 Table of Contents  
REVIEW BRIEF
Year : 2020  |  Volume : 58  |  Issue : 3  |  Page : 186-188

Concerns in the management of large-angle horizontal strabismus


1 Department of Ophthalmology, The Eye Foundation, Coimbatore, Tamil Nadu, India
2 Department of Strabismus and Pediatric Ophthalmology, The Eye Foundation, Coimbatore, Tamil Nadu, India

Date of Submission04-Jun-2020
Date of Decision12-Jul-2020
Date of Acceptance20-Jul-2020
Date of Web Publication14-Sep-2020

Correspondence Address:
Dr. Muralidhar Rajamani
Department of Strabismus and Pediatric Ophthalmology, The Eye Foundation, 582A, D.B. Road, R.S. Puram, Coimbatore - 641 002, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/tjosr.tjosr_68_20

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How to cite this article:
Asafali F, Rajamani M, Periannan C, Michael S, Dandapani R. Concerns in the management of large-angle horizontal strabismus. TNOA J Ophthalmic Sci Res 2020;58:186-8

How to cite this URL:
Asafali F, Rajamani M, Periannan C, Michael S, Dandapani R. Concerns in the management of large-angle horizontal strabismus. TNOA J Ophthalmic Sci Res [serial online] 2020 [cited 2020 Oct 26];58:186-8. Available from: https://www.tnoajosr.com/text.asp?2020/58/3/186/295002



Large-angle horizontal strabismus presents unique challenges in management. The definition of large-angle strabismus has varied in literature. Studies have used a cutoff ranging from 40 to 60 PD to define large-angle strabismus. It is understandable that large-angle strabismus will have a negative impact on the patient's confidence and lifestyle. It must be remembered that measurement of strabismus >120 PD is difficult as most loose prism sets limit the largest prism to 50 PD. Li and Zhang[1] suggested stacking two horizontal prisms, one in front of the other to get an approximate measure.

Most surgical dosage tables dwell on two-muscle surgery. Surgery on one eye would save time and money and preserve the other eye for future surgery. This may, however, fail to address large-angle strabismus. Some authors have, therefore, suggested doing supramaximal surgery on two recti.[2],[3] This is a logical first choice in one-eyed patients with sensory strabismus in the fellow eye. It has been tried successfully by some authors in patients with good vision in both eyes.[4] Dosages in exotropia range from 7 to 12 mm resection for the medial rectus and up to 14 mm recession for the lateral rectus. The authors have noted that such large recessions do not produce substantial restrictions in ocular motility and cosmetically significant changes in the palpebral fissure.[2] The tradeoff of improvement in cosmesis appears certainly worthwhile.

Other studies have not been able to reproduce the success with two-muscle surgery alone and have suggested adding a third or fourth recti. Scott et al.[5] noted that bimedial recessions alone were successful in only 37.5% of patients with large-angle infantile esotropia >50 PD. Adding a third or fourth muscle substantially increased the success rates to 64.5% and reduced the resurgery rates by 4 times. In the absence of validated tables guiding dosing in large-angle strabismus surgery, many approaches have been suggested. Camuglia[6] suggested and validated his surgical dosage table for large-angle infantile esotropia with deviations between 60 and 85 PD. Both medial recti were recessed 10–11 mm from the limbus and one lateral rectus was resected based on the preoperative deviation. The authors reported a success of 100% at 2 months. Lau et al.[7] recessed both lateral recti to 9 mm (for large angle exotropia) aiming for exotropic correction of 50 PD. Any deviation above 50 PD was corrected by resecting the medial rectus with a dosing of 5 PD/mm. The authors reported an overall success of 75%. Only 40% of patients with deviation >80 PD achieved a successful alignment. Chen et al.,[8] however, reported a lower success with three-muscle (67% at 2 months) and four-muscle surgery (44% at 2 months). They, however, noted that adjustable strabismus surgery was more likely to succeed in large-angle strabismus (76% success at 2 months compared to 56% success with conventional surgery).

Considering the findings of the above studies, it is clear that there is no “one-size-fits-all” approach for treating large-angle strabismus. There is a certain measure of variability that needs to be accounted for. It is a difficult proposition to adhere to fixed dosages and number of extraocular muscles. This was aptly reflected in the study by Currie et al.[9] They adopted an individualized approach. 2, 3, or 4 muscles were operated upon depending on the size of deviation, previous surgeries, presence of amblyopia, and any abnormality of extraocular movements. 25 out of 26 patients underwent adjustable strabismus surgery. 77% of patients achieved alignment within 10 PD and 92% were satisfied with their cosmetic outcome. The resurgery rate was only 4%. Li and Zhang[1] reported the results of 3-muscle surgery including recession of lateral rectus on the fixing eye and combined recession of lateral rectus and resection of medial rectus resection on the nonfixing eye for very large angle exotropia (>120 PD). The lateral rectus recession ranged from 9 to 15 mm and the medial rectus resection from 7 to 8 mm. They reported a success rate of 82.6%. All three horizontal recti were placed on adjustable in some of their cases.

We also prefer to follow an individualized approach to large-angle horizontal strabismus. All surgeries are done under topical anesthesia and conscious sedation with intravenous sedation using fentanyl and midazolam. Fentanyl is a synthetic opioid analgesic with shorter duration of action. Midazolam is a short-acting benzodiazepine which allays anxiety.[10] Fentanyl makes the patient insensitive to pain. The hemodynamic parameters are not affected much or it is just minimally altered with administration of fentanyl. After an initial surgery based on the deviation, a call on further surgery/adjustment is taken based on the alignment achieved. This allows us to replan the surgery on a real-time basis and optimize the number of muscles operated upon. We have been able to get 1st day postoperative alignment within 10 PD in almost all our patients with large-angle horizontal strabismus. An example showing pre operative exotropia in [Figure 1] and post operative alignment at the end of 1 month in [Figure 2]..
Figure 1: A 33-year-old female patient with preoperative exotropia of 65 PD for distance and 75 PD for near

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Figure 2: Postoperative alignment at 1 month. The patient was orthotropic for distance and near (she had undergone right lateral rectus recession 7.0 mm with bilateral medial rectus plication of 6.0 mm under topical anesthesia and conscious sedation. The right lateral rectus was placed on adjustable sutures. She was aligned to orthotropia for near and 4 PD esotropia for distance on table. No adjustment was needed. The success was maintained during follow-up)

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To sum up, large-angle strabismus presents many challenges in management. We recommend using adjustable sutures and adopting an individualized approach for managing these patients.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Li JH, Zhang LJ. Three-muscle surgery for very large-angle constant exotropia. J APOS 2013;17:578-1.  Back to cited text no. 1
    
2.
Chang JH, Kim HD, Lee JB, Han SH. Supermaximal recession and resection in large-angle sensory exotropia. Korean J Ophthalmol 2011;25:139-41.  Back to cited text no. 2
    
3.
Celebi S, Kükner AS. Large bilateral lateral rectus recession in large angle divergence excess exotropia. Eur J Ophthalmol 2001;11:6-8.  Back to cited text no. 3
    
4.
ElKamshoushy AA. Accidental duplication: Bilateral medial rectus resection for primary large angle exotropia. J AAPOS 2017;21:112-6.  Back to cited text no. 4
    
5.
Scott WE, Reese PD, Hirsh CR, Flabetich CA. Surgery for large-angle congenital esotropia. Two vs. three and four horizontal muscles. Arch Ophthalmol 1986;104:374-7.  Back to cited text no. 5
    
6.
Camuglia JE, Walsh MJ, Gole GA. Three horizontal muscle surgery for large-angle infantile esotropia: Validation of a table of amounts of surgery. Eye 2011;25:1435-41.  Back to cited text no. 6
    
7.
Lau FH, Fan DS, Yip WW, Yu CB, Lam DS. Surgical outcome of single-staged three horizontal muscles squint surgery for extra-large angle exotropia. Eye (Lond) 2010;24:1171-6.  Back to cited text no. 7
    
8.
Chen JH, Morrison DG, Donahue SP. Three and four horizontal muscle surgery for large angle exotropia. J Pediatr Ophthalmol Strabismus 2015;52:305-10.  Back to cited text no. 8
    
9.
Currie ZI, Shipman T, Burke JP. Surgical correction of large-angle exotropia in adults. Eye (Lond) 2003;17:334-9.  Back to cited text no. 9
    
10.
Liu LL, Gropper MA. Postoperative analgesia and sedation in the adult intensive care unit: A guide to drug selection. Drugs 2003;63:755-67.  Back to cited text no. 10
    


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