Acute visual loss after botulinum toxin A injection in the masseter muscle.

[PURPOSE] Acute visual loss after facial injection of cosmetic materials is rarely reported. In this study, we report one patient who developed acute visual loss after an injection of botulinum toxin A for esthetic purposes.

[METHODS] A 43-year-old Korean woman presented with a decrease in visual acuity to 20/800 after an injection of botulinum toxin A in the masseter muscle. The visual field testing showed an inferior altitudinal defect, and fluorescein angiography revealed a delayed arm-retinal circulation time.

[RESULTS] After intravenous and oral prednisolone was administered, the patient's visual acuity gradually improved. Two months after the botulinum toxin A injection, the visual acuity had almost returned to baseline, with a remaining paracentral scotoma.

[CONCLUSIONS] This is the first case of acute visual loss following an injection of botulinum toxin A in a facial lesion. This case emphasizes that the potential risks of botulinum toxin A injection should be considered, and the procedure should be performed delicately.