Sustained improvement of reading symptoms following botulinum toxin A injection for convergence insufficiency

Abstract

AbstractIntroduction: We evaluated the use of botulinum toxin A in adults with convergence insufficiency in whom prior treatment had failed.Methods: We studied 8 patients (median age 36 years, range 17 to 77 years) with reading symptoms due to convergence insufficiency defined as an exodeviation greater at near, not exceeding 10 PD in the distance measured by prism and alternate cover test, and either convergence near point >6 cm or reduced fusional amplitudes. All patients were still symptomatic after prior treatment by convergence exercises (n = 8), base-in prism glasses (n = 5) or strabismus surgery (n = 2). Five patients received injection of 5 IU botulinum toxin in 0.1 ml saline to one lateral rectus muscle, two received 2.5 IU, and one received 2.5 IU to both lateral rectus muscles.Results: At 1 month post injection, all patients had an initial reduction of exodeviation from baseline (median 9 PD, p = 0.008) at near, although 2 patients had a temporary intermittent esotropia in the distance with dip...