Abstract
Background: Essential infantile esotropia (EIE) is the most common type of childhood esotropia. Although its classical approach is surgical, less invasive techniques have been proposed as an adjunct or alternative to traditional surgery. Among them, chemodenervation with botulinum toxin (BT) has been investigated, showing variable and sometimes conflicting results.Objectives: To compare the outcomes of bilateral BT injection and traditional surgery in a pediatric population with EIE in order to optimize and standardize the therapeutic approach. Other purposes are to evaluate whether early intervention may prevent the onset of vertical ocular deviation (which is part of the clinical picture of EIE) and/or influence the development of fine stereopsis, and also to assess changes in refractive status over time among the enrolled population.Methods: A retrospective consecutive cohort study was conducted in 86 children aged 0–48 months who underwent correction of EIE. The primary intervention in naïve subjects was either bilateral BT injection (36 subjects, “BT group”) or strabismus surgery (50 subjects, “surgery group”).Results: Overall, BT chemodenervation (one or two injections) was effective in 13 (36.1%) subjects. With regard to residual deviation angle, the outcomes at least 5 years after the last intervention were overlapping in children receiving initial treatment with either injection or surgery; however, the success rate of primary intervention in the surgery group was higher, and the average number of interventions necessary to achieve orthotropia was smaller. Both early treatment with chemodenervation and surgery at a later age were not found to prevent the onset of vertical ocular deviation, whereas, surprisingly, the percentage of subjects developing fine stereopsis was higher in the surgery group. Finally, with regard to the change in refractive status over time, most of the subjects increased their initial hyperopia, whereas 10% became myopic.Conclusions: Our data suggest that a single bilateral BT injection by age 2 years should be considered as the first-line treatment of EIE without vertical component; whereas, traditional surgery should be considered as the first-line treatment for all other cases and in subjects unresponsive to primary single BT injection.
Highlights
Essential infantile esotropia (EIE) is the most common type of childhood esodeviation
To differentiate EIE from early-onset accommodative esotropia, full cycloplegic correction was prescribed in all subjects older than 7 months, with mono- or bilateral spherical equivalent (SE) refraction > +2.50 diopters (D); if no change in the strabismic angle was found after optical correction, patients were diagnosed with EIE and enrolled in the study [2]
The refractive cutoff values used take into account the changes in refractive error in aging children with EIE described by Birch et al [9], and the research of Lee et al [10], who found that preoperative hyperopia < +5.00 D does not affect the outcome of EIE surgery
Summary
Essential infantile esotropia (EIE) is the most common type of childhood esodeviation It typically occurs during the first 6 months of life and is characterized by a constant, large angle strabismus, in neurologically normal and otherwise healthy children. In most of the available studies, the inclusion criteria were very broad (in terms of etiology and associated conditions, amount of deviation angle, cycloplegic refraction, etc.) and what it is usually referred to as “infantile” or “congenital” esotropia, comprises various strabismic conditions, other than EIE. This may be misleading and bias data interpretation. Chemodenervation with botulinum toxin (BT) has been investigated, showing variable and sometimes conflicting results
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