Retinal tear and raised intraocular pressure following unintentional intraocular botulinum toxin type A injection

A 67-year-old woman with a 30-year history of dysthyroid orbitopathy and diplopia had an inadvertent injection of botulinum toxin type A into the vitreous cavity. Full pupil mydriasis and an intraocular pressure (IOP) of 50 mm Hg in the right eye were noted after the injection. An attack of acute angle closure was initially suspected despite a patent peripheral iridotomy (PI). The episode resolved with topical and intravenous IOP-lowering agents. Postoperative retinal examination revealed a retinal tear, which was successfully treated with laser photocoagulation. Visual acuity returned to baseline within 2 weeks, and the results of further retinal examinations remained stable.

This case supports the animal studies and human case reports that have demonstrated no retinal toxicity after intraocular injections of botulinum toxin type A. Temporary mydriasis and elevated IOP that may occur after injection do not appear to be detrimental and can be treated with topical and intravenous IOP-lowering agents. Transiently elevated IOP after injection is most likely due to volume increase, though acute angle closure with occlusion of the PI might be considered.