Comparing Botulinum Toxin Injections with Extraocular Muscle Surgery in Toddlers with Esotropia: A Retrospective Analysis

Abstract Background In toddlers with esotropia, early alignment of the visual axes either with extraocular muscle surgery (EOMS) or botulinum toxin injections (BTIs) into both medial rectus muscles may result in improved depth perception. We compared the outcome of BTIs with EOMS in toddlers in order to gain further insight into the advantages and disadvantages of either method. Patients and Methods In this retrospective study, our encrypted database was searched for toddlers with esotropia aged 35 months or younger at the time of initial treatment with either BTIs or EOMS and who had a follow-up of at least 2 years. We analyzed the angle of deviation, dose effect (DE), and binocularity as well as the number of interventions. Results We identified 26 toddlers who received their first treatment for esotropia within the first 35 months of life: 16 with BTIs (9 males, 7 females) and 10 with EOMS (3 males, 7 females). Mean follow-up was considerably longer in the EOMS (87.7 months) than in the BTI group (35.7 months). Age at first intervention was 22.8 months in the BTI and 24.1 months in the EOMS group, and each toddler wore its full cycloplegic refraction. Mean angle at treatment was 41.25 prism diopters (PD) in the BTI compared to 52.9 PD in the EOMS group. The BTI group received an average of 1.68 BTIs, with a mean dosage of 14.5 IU Botox and a mean DE (mDE) of 1.8 PD/IU. In the EOMS group, the average number of surgeries was 1.4, with a mean dosage of 16.85 mm and a mDE of 3.14 PD/mm surgery. Some degree of binocularity could be observed in 9 (56%) of the BTI (5 × Bagolini positive, 2 × 550″, 2 × 220″) and in 4 (40%) of the EOMS group (2 × 3600″, 1 × 550″, 1 × 300″). By the end of the BTI group follow-up, four toddlers electively underwent EOMS rather than a 3rd BTI (followed by a 3rd BTI in 1), which resulted in the appearance of measurable binocularity in all four (1 × Bagolini positive, 1 × 220″, 1 × 200″, 1 × 60″). Conclusions Our results show that BTIs are a viable treatment alternative in early esotropia. Even if EOMS is ultimately required, some binocularity may develop as the visual axes are aligned for some time in the sensitive phase owing to the effects of Botox. Moreover, less surgical dosage is needed than would have otherwise been necessary to treat the original angle of deviation. BTIs are faster, less invasive, and present as an effective alternative when patient compliance is too low to reliably measure the angle of deviation, which is essential for the planning of EOMS.