Injecting botulinum toxin type A into one or more extraocular muscles can help reduce diplopia and may improve binocular function in patients with internuclear ophthalmoplegia, according to a retrospective study by researchers in India. However, patients often require repeat injections, which can limit the treatment benefits, the authors noted.
Ramesh Murthy, MD, FRCS, and colleagues at LV Prasad Eye Institute in Andhra Pradesh reviewed outcomes for 16 patients with internuclear ophthalmoplegia treated with Botox (botulinum toxin type A, Allergan) injections over a 20-year period. The study included nine men and seven women who averaged 45.1 years of age at the time of initial treatment.
The most common causes of patients' internuclear ophthalmoplegia included brainstem hemorrhage (five patients) and multiple sclerosis (four patients), according to the study.
The researchers found that, after receiving the botulinum toxin injections, 14 patients (87.5%) experienced a reduction in diplopia. Also, nine patients (56.3%) had an improvement in their appearance and four (25%) had an improvement in head posture.
Additionally, two patients (12.5%) recovered convergence and three patients (18.8%) had improved stereopsis, the authors reported.
Complications included one patient who developed transient ptosis and one patient who was overcorrected. Two patients also reported transient vertical diplopia, which resolved within 3 weeks.
At final follow-up, five patients (31.5%) continued to receive injections and three patients (18.8%) had stabilized and were discharged. Of the remaining eight patients, five were managed by occlusion therapy, one was managed with prisms and two received surgery, according to the study, published in the October issue of Journal of American Association for Pediatric Ophthalmology and Strabismus.