This literature-non-study case was reported in a literature article and describes the occurrence of OPTIC NEURITIS (inflammatory cranial neuritis) and VITH NERVE PARESIS (bilateral CN VI  paresis) in a 45-year-old female patient who received mRNA-1273 (Spikevax) for COVID-19 vaccination. LITERATURE REFERENCE: Binocular horizontal diplopia following mRNA-1273 vaccine. No Medical History information was reported. On an unknown date, the patient received first dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, received second dose of mRNA-1273 (Spikevax) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient experienced OPTIC NEURITIS (inflammatory cranial neuritis) (seriousness criterion medically significant) and VITH NERVE PARESIS (bilateral CN VI  paresis) (seriousness criterion medically significant). At the time of the report, OPTIC NEURITIS (inflammatory cranial neuritis) and VITH NERVE PARESIS (bilateral CN VI  paresis) was resolving. DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Magnetic resonance imaging: post vaccination inflammatory cranial neuritis (abnormal) confirmation of abducens nerve enhancement consistent with a post vaccination inflammatory cranial neuritis. On an unknown date, Magnetic resonance imaging head: right greater than left enhancement of CN VI orbits showed right greater than left enhancement of CN VI at the proximal cisternal segment and root entry zone. Inflammatory abducens neuritis. There was an additional focus of brainstem enhancement involving the right abducens nerve root entry zone at the pontomedullary junction. and complete resolution of previously seen enhancement. On Follow up of 2 months: showed complete resolution of previously seen enhancement along the right abducens nerve and near-complete resolution of previously seen enhancement of the left abducens nerve. On an unknown date, SARS-CoV-2 test: negative (Negative) Negative. On an unknown date, Visual acuity tests: 20/25 in the right eye and 20/20 in the left eye 20/25 in the right eye and 20/20 in the left eye. On an unknown date, Visual field tests: normal (normal) within normal limits in both eyes. For mRNA-1273 (Spikevax) (Unknown), the reporter considered OPTIC NEURITIS (inflammatory cranial neuritis) and VITH NERVE PARESIS (bilateral CN VI  paresis) to be related. Concomitant and treatment medications was not reported. Patient reported dilated fundus examination was unremarkable. Patient reported cross-cover testing which revealed that a 2-prism diopter esophoria in primary position, 18-diopter esotropia on right gaze, and 8-diopter esotropia on left gaze. There was limited abduction of both eyes, worse in the right eye. 2 months later patient reported, cross-cover testing was revealed that orthophoria in primary position and left gaze and a remaining 18-diopter esotropia in right gaze. However, the patient's young age and absence of vasculopathic risk factors coupled with bilateral enhancement of the abducens nerve and absence of other demyelinating plaques on MRI supports a vaccine-induced immune-mediated neuritis as the most plausible explanation for the patient's presentation. CC: This literature-non-study case concerns a 45-year-old female patient, with no medical history reported, who experienced serious, unexpected events of optic neuritis and VIth nerve paresis, which occurred 4 days after a dose of mRNA-1273. The patient presented painless binocular horizontal diplopia worse on right gaze and lasted 3 weeks. Diplopia was initially intermittent and subsequently became constant. Within this 3-week period, the etiology of her diplopia remained unclear, and neuro-ophthalmology consultation was requested. On follow-up 2 months later, the patient stated her diplopia significantly improved. Cross-cover testing revealed orthophoria in primary position and left gaze and a remaining 18-diopter esotropia in right gaze. A repeat MRI brain and orbits showed complete resolution of previously seen enhancement along the right abducens nerve and near-complete resolution of previously seen enhancement of the left abducens nerve. The patient received her second dose of the mRNA-1273 vaccine 5 weeks after her initial vaccine without adverse effect. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. Sender's Comments: This literature-non-study case concerns a 45-year-old female patient, with no medical history reported, who experienced serious, unexpected events of optic neuritis and VIth nerve paresis, which occurred 4 days after a dose of mRNA-1273. The patient presented painless binocular horizontal diplopia worse on right gaze and lasted 3 weeks. Diplopia was initially intermittent and subsequently became constant. Within this 3-week period, the etiology of her diplopia remained unclear, and neuro-ophthalmology consultation was requested. On follow-up 2 months later, the patient stated her diplopia significantly improved. Cross-cover testing revealed orthophoria in primary position and left gaze and a remaining 18-diopter esotropia in right gaze. A repeat MRI brain and orbits showed complete resolution of previously seen enhancement along the right abducens nerve and near-complete resolution of previously seen enhancement of the left abducens nerve. The patient received her second dose of the mRNA-1273 vaccine 5 weeks after her initial vaccine without adverse effect. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.