DTaP-IPV vaccination-related optic neuritis; headache; pain with ocular movements; intermittent blurred vision; optic nerve swelling; hyperemia in both eyes; dyschromatopsia developed on the left; afferent pupil defect; Initial information received on 20-Mar-2023 via Healthcare Professional regarding an unsolicited valid serious case issued from a literature article:    This case involves a 27-year-old male patient who experienced DTaP-IPV vaccination-related optic neuritis while being treated with Diphtheria, Tetanus, Acellular (AC) Pertussis and Inactivated poliovirus vaccine (IPV) Vaccine(Latency: 1 day).  The patient's past medical history, medical treatment(s), vaccination(s) and family history were not provided.  In 2013, the patient received a dose of suspect Diphtheria, Tetanus, Acellular (AC) Pertussis and Inactivated poliovirus vaccine (IPV) vaccine produced by unknown manufacturer lot number not reported via unknown route in unknown administration site.  In 2013, patient with no significant past medical history presented to an emergency department with a 5-day history of headache, pain with ocular movements (eye pain), and intermittent blurred vision (vision blurred) starting 1 day after being immunized with DTaP-IPV. Magnetic resonance imaging and a magnetic resonance venogram of his brain were unremarkable. A lumbar puncture revealed a normal opening pressure and cerebrospinal fluid studies were positive for myelin basic protein but negative for oligoclonal bands and neuromyelitis optical autoantibody serology. On examination, his best corrected vision was 20/100 in his right eye and 20/70 in his left eye. Intraocular pressures, pupil examination, ocular alignment, and extraocular movements were normal. Confrontational visual fields were restricted in both eyes. Posterior segment examination showed optic nerve swelling (papilloedema) and hyperemia in both eyes (ocular hyperaemia) and two microaneurysms in the mid periphery of his left eye. No evidence of vitritis, retinal vasculitis, or choroiditis was seen in either eye. Serum laboratory testing showed elevated glycated hemoglobin (A1C) at 6.9%, aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Other liver tests including bilirubin, alkaline phosphatase, and hepatitis serologies were normal. Tests for infectious and inflammatory etiologies including angiotensin-converting enzyme (ACE), lysozyme, antinuclear antibody (ANA), cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA), perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), lupus panel, rapid plasma reagin (RPR), fluorescent treponemal antibody absorption (FTA-ABS), chest X-ray, and QuantiFERON Gold assay, which were normal. Over the next 5 days, his vision declined to counting fingers at 30.5 cm (1 foot) in both eyes (Color fundus photography of the optic nerve 5 days after initial presentation when vision dropped to counting fingers at 30.5 cm (1 foot) in both eyes). A relative afferent pupil defect (pupillary reflex impaired) and dyschromatopsia developed on the left (dyschromatopsia). Automated Humphrey visual field (HVF) testing demonstrated global depression in both eyes (Automated 30-2 Humphrey visual field testing using Swedish Interactive Testing Algorithm-Fast protocol of (a) the right eye and (b) the left eye showing gray tone and pattern deviation). He was diagnosed as having DTaP-IPV vaccination-related optic neuritis (optic neuritis) and on September 11, 2013, started on intravenously administered Solu-Medrol (methylprednisolone) (Corrective treatment). One week later, his headache resolved, and vision improved to 20/20 in his right eye and 20/25 in his left eye with less optic nerve hyperemia and swelling. Follow-up perimetry 1 week and 3 weeks after the initiation of systemic corticosteroids showing improvement and resolution of the visual field deficits He was discharged on a prednisone (Corrective treatment) taper and an orally administered diabetic medication. One month later, his vision improved to 20/20 with resolution of the optic neuritis without residual visual field deficit in both eyes.  Seriousness criteria: Hospitalization and medically significant for the event. Action taken: Not applicable for the suspect. Corrective treatment: Solu-Medrol (methylprednisolone) and prednisone for the event DTaP-IPV vaccination-related optic neuritis. Outcome: Recovered for the event. Reporter's causality: Related with the suspect with respect to event.; Sender's Comments: Sanofi company comment on dated 28-Mar-2023: This case involves a 27-year-old male patient who experienced DTaP-IPV vaccination-related optic neuritis while being treated with Diphtheria, Tetanus, Acellular (AC) Pertussis and Inactivated poliovirus vaccine (IPV) Vaccine (Latency: 1 day). Based on the limited information received the causal role of VACCINE cannot be excluded due to compatible temporal relationship of ADR to the VACCINE. Further information regarding concurrent condition during vaccination, previous vaccination, tolerance, allergic history, laboratory investigations excluding alternative etiologies for the reported event are needed to fully assess this case. Based upon the reported information, the role of vaccine cannot be assessed completely.