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Year : 2021  |  Volume : 1  |  Issue : 3  |  Page : 582-584

Botulinum toxin: A surgery-sparing strategy for cyclic esotropia

Department of Pediatric Ophthalmology and Strabismus, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Coimbatore, Tamil Nadu, India

Date of Submission07-Sep-2020
Date of Acceptance11-Jan-2021
Date of Web Publication02-Jul-2021

Correspondence Address:
Dr. D S Srushti
Department of Pediatric Ophthalmology and Strabismus, Aravind Eye Hospital and Post Graduate Institute of Ophthalmology, Coimbatore, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijo.IJO_2896_20

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Cyclic esotropia is associated with alternating periods of esotropia and orthotropia within a defined cycle, occurring typically in pre-school children. Therapeutic options include surgery which is based on strabismic day angle, or injection of botulinum toxin into the medial rectus muscle. The latter is a simpler, less invasive, and potentially surgery sparing option causing a temporary drug-induced muscle paresis and providing enough opportunity to regain the fusion potential. We report one such case of childhood cyclic esotropia treated with injection botulinum toxin.

Keywords: Botulinum toxin, childhood acquired esotropia, cyclic esotropia, surgery sparing technique

How to cite this article:
Ganesh SC, Srushti D S, Narendran K. Botulinum toxin: A surgery-sparing strategy for cyclic esotropia. Indian J Ophthalmol Case Rep 2021;1:582-4

How to cite this URL:
Ganesh SC, Srushti D S, Narendran K. Botulinum toxin: A surgery-sparing strategy for cyclic esotropia. Indian J Ophthalmol Case Rep [serial online] 2021 [cited 2021 Jul 28];1:582-4. Available from: https://www.ijoreports.in/text.asp?2021/1/3/582/320022

Cyclic esotropia is a rare condition as described by Burian in 1958,[1] characterized by alternating periods of esotropia and orthotropia with a 48-h periodicity (range 24–96 h).[2] Cyclic esotropia mostly affects preschoolers, but adult-onset cases have also been reported.[2],[3] Though typically an acquired form of concomitant non-accommodative strabismus, cases associated with accommodative, infantile, consecutive, and secondary deviations have been reported.[1] The exact pathophysiologic mechanism remains speculative.

The natural evolution, if left untreated, is the break of the cyclical pattern and transformation into a constant strabismus. Being an acquired strabismus with binocularity at risk, it is essential to actively intervene at the earliest.[4] The main treatment option for cyclic esotropia is surgery, preferably before the development of constant esotropia.[2],[3],[5] The alternative treatment is botulinum toxin type A injection as reported in limited case reports.[2],[6]

We hereby report our experience in a case of cyclic esotropia treated with injection botulinum toxin type A, which successfully broke the cycle and appears to exhibit a promising non-surgical treatment alternative.

  Case Report Top

A 5-year-old boy presented with intermittent inward deviation of his right eye over the past 1 year. The deviation was seen for a day or two and disappeared for another 2–3 days. This pattern persisted over the past 3–4 months. There was no history of occlusion therapy or previous eye muscle surgery. On examination, child's visual acuity was 20/40 unaided in either eye which improved to 20/20 (–1.0 [email protected]° OU). Orthoptic examination revealed comitant esotropia of 60 PD for distance and 65 PD for near with left eye dominance [Figure 1]a. His responses to tests of sensory evaluation (W4DT, Lang's stereo) were ambiguous. Parents showed pictures showing straight eyes on few days. Cycloplegic refraction correlated with the glasses that the child was wearing.
Figure 1: Pre-treatment photographs taken on patientfs strabismic day (a) and non strabismic day (b)

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Parents were asked to document the frequency and duration of deviation. Charting suggested a frequency of inward deviation every 72 h lasting for 48 h. The diagnosis of cyclic esotropia was confirmed.

The child's parents consented for Injection botulinum toxin as treatment option. They were counseled regarding the short term effect of the drug and possible need for further surgical intervention in case of recurrence.

On the day of injection, child was orthotropic [Figure 1]b. Under total intravenous anesthesia, under aseptic precautions in operation theater, forced duction test was performed and found negative for medial rectus contracture. Right medial rectus muscle was identified transconjunctivally, held with forceps and 5 IU of injection botulinum toxin type-A (Botox; Allergan, Dublin, Ireland) was injected into the muscle belly. No EMG support was used. [Video Clip 1].

Child was then discharged under topical antibiotic cover and reviewed after 2 weeks. His mother noted inward deviation just 1 day post-injection, and henceforth he appeared straight. Parents noted drooping of his right upper eyelid 12 days after injection [Figure 2]a.
Figure 2: Post-injection follow-up of 2 weeks (a) showing orthotropia with mild ptosis of right upper lid, 3 months (b) showing disappearance of ptosis and orthotropia, 6 and 10 months follow-up (c and d) showing maintained orthotropia

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At 2 weeks [Figure 2]a and 3 months [Figure 2]b post-injection visits, child showed esophoria of 10 PD for distance and 6 PD for near. BSV was present for near (W4DT). However, his responses were unclear for BSV at distance and stereopsis. Right upper lid showed mild ptosis at 2 weeks and had recovered completely at 3 months post-injection.

Child was reviewed at 6 months post-injection and at the latest, 10 months post-injection. He remains orthotropic [Figure 2]c and [Figure 2]d with binocularity for both distance and near. Stereopsis was recorded as 400 sec of arc.

  Discussion Top

Cyclic esotropia is an acquired form of strabismus with excellent potential for regaining binocularity and stereopsis. It is therefore important to intervene at the earliest.[4]

In childhood, cyclic strabismus is typically spontaneous with an average age of onset being 3–4 years. During the orthotropic phase, children generally have a fully controlled heterophoria at all distances, with good fusion and stereopsis.[5]

Surgery based on the magnitude of heterotropia, as measured on a “strabismic” day, is often successful in permanently curing the condition.[1] This gives excellent results, with no overcorrection on the previously “non-strabismic” days.[5] However, postoperative complications and failures have also been reported, including development of cyclic exotropia, consecutive exotropia or the cycle not breaking.[3],[6]

The alternative to conventional surgery is botulinum toxin injection. The potential for fusion in children with acquired esotropia[4] theoretically makes them good candidates for this therapy.[7] Akyuz Unsal AI et al.[2] reported long-term follow-up of cyclic esotropia treated with botulinum toxin A in two of his cases. Both the children successfully maintained orthotropia with binocularity and high-grade stereopsis for 8 and 9 years post-injection. The authors also compiled other case reports of cyclic esotropia by Jones et al.[6] Wipf et al.[8] and Sohn et al.[9] managed by botulinum toxin injection with positive outcomes, but with shorter follow-up.

However, a case of adult-onset cyclic esotropia reported by Lai YH, et al.[7] experienced only temporary break of cycle after botulinum toxin injection. The patient had to undergo surgical correction of constant esotropia subsequently. [Summarized in [Table 1]].
Table 1: Summary of the reports on injection botulinum toxin for cyclic esotropia

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This procedure is safe in children, the reported adverse events only include transient ptosis and/or vertical deviation.[10] It is less invasive, non-scarring and requires only short anesthesia. In contrast, surgery is invasive, induces scarring, and requires longer and deeper anesthesia.

  Conclusion Top

The role of botulinum toxin should be further explored in cyclic esotropia with a long term follow-up. With possible benefits of sparing invasive surgery and the post-surgical complications, the chemo-denervation approach, if successful, would aid in excellent fusion potential in children with a minimally invasive procedure. However, the remote chances of variable outcome including recurrence of deviation should be borne in mind and explained to the parents prior to the procedure.

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


Conflicts of interest

There are no conflicts of interest.

  References Top

Costenbader FD, Mousel DK. Cyclic esotropia. Arch Ophthalmol 1964;71:180-1.  Back to cited text no. 1
AkyuzUnsal AI, Ozkan SB, Ziylan S. Role of botulinum toxin type A in cyclic esotropia: A long-term follow-up. J Pediatr Ophthalmol Strabismus 2019;56:360-4.  Back to cited text no. 2
Meo AD, Costagliola C, Della Corte M, Romano A, Foria C, Di Costanzo A. Adult-onset cyclic esotropia: A case report. Optom Vis Sci 2013;90:95-8.  Back to cited text no. 3
Wright KW. Esotropia. In: Wright KW, editor. Pediatric Ophthalmology and Strabismus. St Louis: Mosby; 1995. p. 179-94.  Back to cited text no. 4
Souza-Dias C, Kushner BJ, Rebouças de Carvalho LE. Long-term follow-up of cyclic esotropia. J Binocul Vis Ocul Motil 2018;68:148-53.  Back to cited text no. 5
Jones A, Jain S. Botulinum toxin: A novel treatment for pediatric cyclic esotropia. J AAPOS 2014;18:614-5.  Back to cited text no. 6
Lai YH, Fredrick DR. Alteration of cyclic frequency by botulinum toxin injection in adult onset cyclic esotropia. Br J Ophthalmol. 2005;89:1540-1.  Back to cited text no. 7
Wipf M, Bok-Beaube C, Palmowski-Wolfe A. Botulinum toxin for the treatment of cyclic strabismus in children: Three case reports. Klin Monatsbl Augenheilkd 2018;235:465-8.  Back to cited text no. 8
Sohn MA, Lee TD. A case of cyclic esotropia cured by botulinum toxin injection. J Korean Ophthalmol Soc 1999;40:2645-50.  Back to cited text no. 9
Rowe FJ, Noonan CP. Botulinum toxin for the treatment of strabismus. Cochrane Database Syst Rev 2017;3:CD006499.  Back to cited text no. 10


  [Figure 1], [Figure 2]

  [Table 1]


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