Botulinum Toxin Injection with Conjunctival Microincision for the Treatment of Acute Acquired Comitant Esotropia and Its Effectiveness

Abstract

Purpose. To report on an improved botulinum toxin injection with conjunctival microincision for beginners, and to determine the effectiveness of botulinum toxin A (BTXA) in the treatment of patients with acute acquired comitant esotropia (AACE). Methods. Medical records of 29 AACE patients were retrospectively analyzed. BTXA was injected into the unilateral or bilateral medial rectus muscle with conjunctival microincision without electromyographic guidance. Success was defined as total horizontal deviation ≤10 prism diopters (PD) and evidence of binocular vision. Results. Twenty-nine patients were included, of whom 22 were male and 7 were female. The mean age at onset was 14.2 ± 7.4 (range, 4–34) years. The mean time from onset of AACE to injection was 18.4 ± 20.3 (range, 1–96) weeks. All patients completed at least 6 months of follow-up, and the mean follow-up after BTXA injection was 12.3 ± 4.8 months (range, 7–24 months). Neurological evaluation and brain magnetic resonance imaging (MRI) were unremarkable in all patients. The mean spherical equivalent refraction was −1.22 ± 2.85D and −0.97 ± 2.80D in the right and left eyes, respectively. Mean preinjective esotropia was 38.4 ± 18.9 PD (range, +10–+80 PD) at near and 40.2 ± 17.7 PD (range, +20–+80 PD) at far distance. The mean angle of deviation at 6 months after injection was 0.6 ± 4.1 PD (range, −3–+15 PD) at near and 3.0 ± 5.9 PD (range, 0–+20 PD) at far distance. There was significant difference in the angle of deviation at near and far fixation between pre-BTXA and post-BTXA 6 months ( p < 0.001 , p < 0.001 , resp.). There was no significant difference in the angle of deviation at near and far fixation between post-BTXA 6 months and post-BTXA at final follow-up ( p = 0.259 and 0.326, resp.). Mean stereoacuity improved from 338 to 88 arc seconds. During the follow-up period, 5 of 29 patients had recurrent esotropia. Two patients refused all further treatment, and the other 3 patients required incisional strabismus surgery. The success rates were 86.2% (25/29) at 6 months and 82.8% (24/29) at final follow-up. Conclusion. Conjunctival microincision injection of botulinum toxin is a practical and safe method for beginners to locate an extraocular muscle, which is as effective as the traditional methods. Botulinum toxin injection can be preferred as the first-line treatment for AACE patients with potential binocular vision.

Botulinum Toxin Injection versus Extraocular Muscle Surgery for Acute Acquired Comitant Esotropia

“…However, although the direct effect of botulinum toxin lasted only three months, its effect on eye position can last longer. 19 In Xu study, the effects lasted longer than six months, 17 and in our study, the deviation angle was smaller at six months than before treatment. This long-lasting effect may be beneficial to patients who refuse conventional surgery or general anesthesia.…”

“…A retrospective study by Xu et al 17 examined 29 AACE patients who received botulinum toxin injection to determine the treatment’s effectiveness. The dose of botulinum toxin used varied by preoperative deviation angle (5 IU, 6 IU, and 7 IU for deviation angles of 20–40 PD, 40–60 PD, and 60–80 PD, respectively), which resulted in a success rate of 86.2% at six months and 82.8% at the final follow-up.…”

Botulinum toxin type A in treating early-stage patients with small-angle acute acquired comitant esotropia

“…Dawson et al's [10] study revealed that timely BTXA injections within 8wk of onset resulted in favorable outcomes, with 80% of children remaining orthoptic and gradually establishing stereopsis. Similarly, Wan et al [11] reported an average onset-totreatment duration of 3mo, while Xu et al [42] observed a success rate of 82.8% at a 6-month follow-up, with onset-to-treatment ranging from 1 to 96wk. These findings collectively suggest that early BTXA application is practical in AACE treatment.…”

“…While there is no strict prohibition against attempting BTXA treatment for large-angle AACE, established norms and indications suggest its relatively positive efficacy in small to moderate deviations of comitant strabismus (<40 Δ ) [40] . Previous analyses have not analyzed the efficacy of a range of deviations in isolation, and subjects have often included small deviations as well as large angles of AACE [10][11][13][14][41][42] . Consequently, this study focuses on the clinically prevalent range of AACE with small deviations (≤25 Δ ).…”

The efficacy of botulinum toxin type A treatment and surgery for acute acquired comitant esotropia

“…Careful surgical planning and operation can prevent severe complications, including scleral perforations, orbital inflammation, muscle slip, and anesthesia complications (20). BTXA was also found to be a safe, effective, and repeatable treatment for AACE, with fewer iatrogenic injuries (10,17,21,22). Because of the individual response of BTXA (18), and limitations of the syringe scale, surgeons cannot precisely administer BTXA doses according to the deviation.…”