[Clinical observation of botulinum toxin A injection in the treatment of acute comitant esotropia: a retrospective cohort study].

ABSTRACT

Objective: To observe the efficacy and safety of botulinum toxin A (BTA) injection in the treatment of acute comitant esotropia (ACE) with different doses. Methods: This retrospective cohort study included data from patients with ACE who received BTA injection treatment at the First Affiliated Hospital of Zhengzhou University from June 2019 to June 2022. All patients underwent routine ophthalmic examinations, including best-corrected visual acuity (BCVA), spherical equivalent (SE), as well as specialized examinations for strabismus, including the degree of esotropia, eye movement status, and binocular visual function. Patients were categorized into small esotropia [≤60 prism diopters (PD)] and large esotropia (>60 PD) groups based on the pre-treatment degree of esotropia. Each group was further divided into 2.5 U and 5.0 U dose subgroups. Monocular injections were administered to the non-dominant eye. The esotropia degree was recorded and compared at 1, 2, 3, and 6 months of follow-up. The proportion of effectively treated patients in each group was documented. The number of cases with various levels of visual functions (including simultaneous vision, near stereopsis, and distance stereopsis) at 6 months post-treatment was compared, and complications during the follow-up period were observed. Statistical analyses were conducted using t-tests, Mann-Whitney U tests, and χ2 tests. Results: A total of 70 patients were included in the study, comprising 46 males and 24 females, with a median age of 5.0 (4.0, 8.3) years. Among them, 37 patients had small esotropia, with 25 in the 2.5 U group and 12 in the 5.0 U group. Thirty-three patients had large esotropia, with 18 in the 2.5 U group and 15 in the 5.0 U group. There were no statistically significant differences in baseline data, including age, duration of the condition, pre-treatment esotropia degree, BCVA and SE, between the two dose groups in both small and large esotropia patients (all P>0.05). In small esotropia patients, at 1 and 2 months post-treatment, the esotropia degree in the 5.0 U group was -20.00 (-37.50, -7.00) and 0.00 (0.00, 0.00) PD, respectively, which was significantly lower than the 0.00 (-10.00, 4.50) and 5.00 (0.00, 6.50) PD in the 2.5 U group (all P<0.05). At 3 and 6 months post-treatment, the esotropia degree in the 2.5 U group was 5.00 (0.00, 15.00) and 2.00 (0.00, 6.00) PD, respectively, while in the 5.0 U group, it was 0.00 (0.00, 4.50) and 0.00 (0.00, 3.75) PD, with no statistically significant differences between the two groups (all P>0.05). In the 2.5 U group, 20 cases were effectively treated, accounting for 80.0%, while in the 5.0 U group, 10 cases were effective, accounting for 10/12, with no significant difference between the two groups (P>0.05). In the 2.5 U group and the 5.0 U group, the proportions of cases with various levels of visual functions were as follows simultaneous vision, 76.0% (19/25) and 10/12; near stereopsis, 48.0% (12/25) and 7/12; distance stereopsis, 44.0% (11/25) and 7/12, respectively. No statistically significant differences were observed in these proportions (all P>0.05). In patients with large esotropia, the esotropia degrees in the 5.0 U group at various follow-up times were -5.00 (-25.00, 5.00), 0.00 (0.00, 7.00), 2.00 (0.00, 10.00), and 5.00 (0.00, 7.00) PD, respectively. For the 2.5 U group, the corresponding values were 5.00 (2.75, 27.75), 10.00 (3.75, 24.75), 12.00 (3.75, 38.75), and 14.00 (3.50, 54.00) PD, respectively. The esotropia degrees in the 5.0 U group were consistently lower than those in the 2.5 U group (all P<0.05). The proportion of effective treatment in the 5.0 U group (13/15) was higher than that in the 2.5 U group (9/18), and the proportion of cases with distance stereopsis in the 5.0 U group (9/15) was higher than that in the 2.5 U group (4/18), both showing statistically significant differences (all P<0.05). The number of cases with simultaneous vision and near stereopsis showed no significant differences between the two groups (all P>0.05). The proportion of complications in the 2.5 U and 5.0 U groups in both large and small esotropia patients was 9/18, 13/15, 80.0% (20/25), and 10/12, respectively, with no statistically significant differences (all P>0.05). All complications spontaneously resolved within 3 months post-treatment. Conclusions: BTA injection is effective in the treatment of ACE, and for ACE patients with esotropia degrees greater than 60 PD, increasing the injection dose to 5.0 U can achieve better therapeutic outcomes.