Role of Botulinum Toxin Type A in Cyclic Esotropia: A Long-Term Follow-up

Abstract

Purpose: To describe two patients with childhood cyclic esotropia 8 and 9 years after they underwent botulinum toxin type A treatment to report its long-term outcome. Methods: Two patients with sudden onset cyclic esotropia aged 2 and 4 years were included. Botulinum toxin type A injections were performed on the appropriate muscles. Results: The first patient was a 2-year-old boy with left dominant alternating esotropia on a cyclic basis. His strabismus ranged from 25 to 45 prism diopters (PD) at near and distance. A botulinum toxin type A injection into the left medial rectus muscle revealed orthotropia at near and distance with a stereopsis of 60 seconds of arc (arcsec). During the 9 years of follow-up, he remained stable. The second patient was a 4-year-old girl who complained of double vision and strabismus. Her deviation was 40 PD at near and 35 PD at distance on a cyclic pattern. She became orthotropic with glasses after a bimedial botulinum toxin A injection. During the 8 years of follow-up, she remained stable with a stereo-acuity of 120 arcsec. Conclusions: Considering the consecutive and recurrent deviations with surgical treatment in previous reports, botulinum toxin type A is an appropriate first-line option for the treatment of cyclic deviations, despite its limitations. The results suggest that botulinum toxin type A is an effective method to break the cycle in cyclic esotropia permanently. [ J Pediatr Ophthalmol Strabismus . 2019;56(6):360–364.]

Golden Indications and an Overview on the Use of Botulinum Toxin in Strabismus

“…The results with BTXA injection were found to be encouraging in previous reports, including ours. 49 , 50 , 51 In our case study with long-term follow-up of 8 years, we found that BTXA may either provide a cure or break the cycle. 51 Thus, we consider cyclic deviations among the golden indications.…”

“… 49 , 50 , 51 In our case study with long-term follow-up of 8 years, we found that BTXA may either provide a cure or break the cycle. 51 Thus, we consider cyclic deviations among the golden indications.…”

A Conservative Approach by Unilateral Maximal Single-Muscle Recession Surgery for the Treatment of Cyclic Esotropia

“…Cyclic esotropia, characterized by periodic cycles of strictly repetitive “straight” and “crossed” eyes, is an extremely uncommon form of nonaccommodative convergent strabismus with an incidence between 1/3000 and 1/5000 and has been reported more commonly than cyclic exotropia or cyclic vertical deviations [ 1 , 2 ]. Most cases occur spontaneously in childhood and are congenital but may be acquired after conditions that disrupt fusion or cause diplopia such as optic atrophy, ocular myositis, trauma, ocular or strabismic surgery, and CNS abnormalities [ 4 ].…”

“…Nonsurgical approaches by botulinum toxin injections to one or both medial rectus muscles may be an alternative way to permanently treat this unique disease. Indeed, an article demonstrated that 2 children with cyclic esotropia were successfully treated with a unilateral or bilateral single dose of botulinum toxin injection for at least 8 years of long-term follow-up [ 2 ]. So, botulinum toxin could be a conservative and predictable alternative way to break the cycle permanently, despite its limitations [ 7 ].…”

“…Cyclic esotropia is a mysterious phenomenon that most commonly occurs in early childhood and is characterized by a large angle of manifest but circadian esodeviation of the eye (crossed every other day) [ 1 ]. Classical cyclic esotropia has a 48-hour circadian rhythm of fixed orthophoria and esotropia that is associated with poor binocular function and suppression on “strabismic” days, though 24- to 96-hour cycles have also been described [ 2 ]. The conventional treatment is by two-muscle surgery, bimedial rectus muscle recession with or without posterior fixation sutures, or a unilateral recession/resection procedure according to the manifest deviation on the esotropic day [ 1 ].…”