Botulinum Toxin A Injection for Convergence Insufficiency.

Purpose: To evaluate the effects of botulinum toxin A injection in one or both lateral rectus muscles in patients with convergence insufficiency previously managed with non-surgical and/or surgical options other than botulinum toxin A injection.

Methods: All patients with symptomatic convergence insufficiency treated with botulinum toxin A injection to one or both lateral rectus muscles from 2013 to 2018 at the Department of Ophthalmology, Rigshospitalet-Glostrup, Copenhagen University Hospital were retrospectively reviewed. All patients had near symptoms and were previously treated with a combination of convergence exercises, prisms, and/or surgery. Patients with previous botulinum toxin A injection in an extraocular muscle were excluded. Reading symptoms and deviation at near and distance were recorded at baseline and after 1 and 6 months.

Results: Twenty-three patients with convergence insufficiency were included (8 men and 15 women). Follow-up was conducted after a median of 47 days (interquartile range [IQR]: 31.5 to 72.5 days) and 174 days (IQR: 139 to 267 days). At baseline, median near angle of deviation was 18 PD of exophoria (IQR: 13 to 21 PD). The near deviation was reduced to 10 PD of exophoria (IQR: 7 to 17 PD) at first follow-up visit and 14 PD of exophoria (IQR: 12 to 18 PD) at last follow-up visit. Thirteen of 23 patients (57%) and 3 of 13 patients (23%) reported improvement in reading symptoms at first and last follow-up visit, respectively, compared to baseline.

Conclusions: Botulinum toxin A injection may be useful in patients with convergence insufficiency. However, some patients may require repeated injections. .