double vision; Booster; 4th cranial nerve palsy; On 21Oct2021, got booster dose COVID-19 Vaccine; believes on 21Oct2021 he had his seasonal Flu shot; This is a spontaneous report received from contactable reporter (Consumer) from medical information team. The reporter is the patient.  A 79 year-old male patient received bnt162b2 (BNT162B2), administered in arm left, administration date 21Oct2021 (Lot number: FG3527) at the age of 79 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "cataract surgery" (unspecified if ongoing). Family medical history relevant to adverse events was none. Concomitant medication(s) included: FLU, administration date 21Oct2021. Vaccination history included: Bnt162b2 (Dose 1, NDC/EXP: Unknown, LOT: EL3302, Dose: Unknown , Route: injected into left arm), administration date: 01Feb2021, when the patient was 78 years old, for Covid-19 Immunization; Bnt162b2 (Dose 2, NDC/EXP: Unknown, LOT: EL3247, Dose: Unknown , Route: injected into left arm), administration date: 01Mar2021, when the patient was 78 years old, for Covid-19 Immunization; Flu shot, reaction(s): "never had a problem". Additional vaccines administered on same date of the Pfizer suspect was none (as reported). The following information was reported: IMMUNISATION (hospitalization) with onset 21Oct2021, outcome "unknown", described as "Booster"; DIPLOPIA (hospitalization) with onset 23Oct2021, outcome "not recovered", described as "double vision"; IVTH NERVE PARALYSIS (hospitalization) with onset 2021, outcome "unknown", described as "4th cranial nerve palsy"; PRODUCT USE ISSUE (non-serious) with onset 21Oct2021, outcome "unknown", described as "On 21Oct2021, got booster dose COVID-19 Vaccine; believes on 21Oct2021 he had his seasonal Flu shot". The patient was hospitalized for immunisation, diplopia, ivth nerve paralysis (start date: 24Oct2021, discharge date: 25Oct2021, hospitalization duration: 1 day(s)). The events "double vision" and "4th cranial nerve palsy" were evaluated at the emergency room visit. Went over his symptoms. Red flag goes up that maybe the double vision is a sign of a stroke. He went through a whole bunch of questions. Nurse advised she doesn't think this is a stroke. The nurse from his primary care office doesn't think caller had a stroke, but that something is going on and it could be 4th cranial nerve palsy. Was advised to contact his Ophthalmologist. because he had cataract surgery. Relayed his symptoms to the Ophthalmologist who also thought 4th cranial nerve palsy and advised caller to go to the ER. He went to the ER. He was kept in the ER and then admitted. Then had a bunch of different doctors come in and check for different things. Doctors unsure of what's going on. He's talked to his doctors and was told there's nothing they can do about the double vision at this point other than they think it's the 4th cranial nerve palsy. Spoke with a neuro optometrist who also thought it was 4th cranial nerve palsy. This Neuro Optometrist passively said it could be related to the COVID-19 Vaccine booster, but he didn't think so. Nothing can be found cardiovascular wise, no TIA, and nothing nerve wise in his head. The patient underwent the following laboratory tests and procedures: computerised tomogram (CT scan): (24Oct2021) everything came back clean; echocardiogram: (24Oct2021) everything came back clean; magnetic resonance imaging (MRI and MRI-A both with and without contrast on both orbits): (06Dec2021) negative, notes: nothing was found.