Significant hyperopic refractive error should be corrected by prescribing the full cycloplegic refraction. A small-angle esotropia that is variable in degree or intermittent may be more likely to respond to hyperopic correction than would a large-angle or constant esotropia.
Ocular alignment is rarely achieved without surgery in early-onset esotropia. Previously, it was thought that concurrent amblyopia should be fully treated before surgery. However, it has recently been shown that successful postoperative alignment is as likely to occur in patients with mild to moderate amblyopia at the time of surgery as it is in those whose amblyopia has been fully treated preoperatively. When ocular alignment is achieved earlier, there may be the added benefits of better fusion, stereopsis, and long-term stability.
The goal of surgical treatment of infantile esotropia is to reduce the deviation to orthotropia or as close to it as possible. In the presence of normal vision, this ideally results in the development of some degree of sensory fusion. Alignment within 8Δ–10Δ of orthotropia frequently results in the development of the monofixation syndrome, characterized by peripheral fusion, central suppression, and favorable appearance (see Chapter 5). This small-angle strabismus generally represents a stable, functional surgical outcome even though bifoveal fusion is not achieved; it is therefore considered a successful surgical result. In addition, the child’s psychological and motor development may improve and accelerate after the eyes are straightened.
Most ophthalmologists in North America agree that surgery should be undertaken early. The belief is that the eyes should be aligned by 2 years of age, preferably earlier, to optimize binocular cooperation. Surgery can be performed in healthy children as early as age 4 months. The Congenital Esotropia Observational Study showed that when patients present with constant esotropia of at least 40Δ after 10 weeks of age, the deviations are unlikely to resolve spontaneously. Smaller angles can be monitored, as they may improve spontaneously. A prospective, multicenter European study (ELISSS) comparing early (age 6–24 months) versus delayed (age 32–60 months) strabismus surgery showed a small improvement in gross binocularity in the early-surgery group; however, a higher number of procedures were performed in the early-surgery group.
Various surgical approaches have been suggested for infantile esotropia. The most commonly performed initial procedure is recession of both medial rectus muscles. Recession of a medial rectus muscle combined with resection of the ipsilateral lateral rectus muscle is also effective. Two-muscle surgery spares the other horizontal rectus muscles for subsequent surgery should it be necessary, which is not uncommon. For infants with large deviations (typically >60Δ), some surgeons operate on 3 or even 4 horizontal rectus muscles at the time of the initial surgery, or they add botulinum toxin injection to the medial rectus muscle recession. Significant inferior oblique muscle overaction can be treated at the time of the initial surgery. Chapter 14 discusses surgical procedures in detail.
Injection of botulinum toxin to the medial rectus muscles has also been used as primary treatment of infantile esotropia. In a recent study, botulinum toxin injection was associated with a substantially higher reoperation rate than was strabismus surgery, and children treated with botulinum toxin were found to have a higher rate of postoperative abnormal binocularity. Botulinum toxin may be most useful for smaller deviations.
Leffler CT, Vaziri K, Schwartz SG, et al. Rates of reoperation and abnormal binocularity following strabismus surgery in children. Am J Ophthalmol. 2016;162:159–166.e9.
Pediatric Eye Disease Investigator Group. The clinical spectrum of early-onset esotropia: experience of the Congenital Esotropia Observational Study. Am J Ophthalmol. 2002; 133(1):102–108.
Simonsz HJ, Kolling GH, Unnebrink K. Final report of the early vs. late infantile strabismus surgery study (ELISSS), a controlled, prospective, multicenter study. Strabismus. 2005; 13(4):169–199.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.