Acquired bilateral inferior oblique muscle paralysis following facial injections of botulinum toxin.

Purpose: To report a unique case of bilateral isolated inferior oblique muscle paralysis (IOP) causing torsional diplopia following facial botulinum toxin (BTX) injections. Case report: A 37-year-old female presented with acute-onset torsional diplopia, exacerbated in primary and upward gaze, and alleviated on downward gaze. Neurological evaluations, including cranial/orbital MRI and neostigmine testing, were negative. Ophthalmic examination demonstrated bilateral incyclotorsion, consistent with bilateral IOP. History revealed recent periocular BTX injections for infraorbital rhytids, and experienced post-injection dizziness that necessitated a 30-min recumbent position. Notably, diplopia risk was undisclosed during consent. Symptoms resolved spontaneously within a week and did not recur over three years. Conclusion: This case emphasizes the need for careful injection practices, proper post - injection care, informed consent, and vigilance for atypical symptoms to prevent and manage BTX - related ophthalmic complications.