Lateral canthal botulinum toxin injection caused transient esotropia and diplopia

A 39-year-old female developed transient esotropia and horizontal binocular diplopia five days after receiving cosmetic botulinum toxin type A injections to her glabellar, forehead, and lateral canthal regions. The injections, performed at a non-medical beauty center, were placed within 1 to 1.5 centimeters of the lateral orbital margin. Upon ophthalmic examination, the patient maintained normal 0.0 logMAR visual acuity bilaterally but exhibited a 10-prism-diopter esodeviation in primary gaze, right-eye suppression on Worth four-dot testing, and reduced stereopsis. This presentation suggests lateral rectus muscle paresis caused by localized toxin diffusion. Clinicians managed the case conservatively using temporary prism lenses, reducing the strength from 8 to 6, then 2 prism diopters, until discontinuation at month four. Full resolution of the diplopia and normalized ocular alignment were achieved at month six. For medical injectors, this case underscores the anatomical risk of placing lateral canthal injections too close to the lateral orbital rim, demonstrating why precise depth control and maintaining a safe 1.5-centimeter distance from the bony margin are critical to avoid extraocular muscle paresis.

Source: ResearchGate / Journal of Cosmetic Dermatology, https://www.researchgate.net/publication/382348574_Cosmetic_BoNT-A-Induced_Transient_Esotropia_A_Case_Expanding_the_Clinical_Spectrum_of_Lateral_Rectus_Involvement