Acute macular neuroretinopathy associated with influenza vaccination with decreased flow at the deep capillary plexus on OCT angiography

Purpose: We report a case of acute macular neuroretinopathy (AMN) following routine annual inactivated influenza vaccination. Projection-resolved optical coherence tomography angiography (PR-OCTA) was used to analyze the retinal capillary flow within the AMN lesion. Observations: Our patient reported visual symptoms of her right eye nine days after routine annual influenza vaccination. Multimodal imaging revealed small vessel peripheral vasculitis and AMN in the affected eye. Infectious, immunologic, and hypercoagulable etiologies were investigated and excluded. PR-OCTA B-scans within the AMN lesion demonstrated reduced flow in the deep capillary plexus (DCP) at baseline with relatively improved flow signal in the DCP on follow up, 3 weeks later. Conclusions and importance: We report a new association of AMN following routine inactivated influenza immunization. Recent influenza vaccination should be included in the differential diagnosis for patients presenting with AMN. PR-OCTA demonstrated compromised DCP flow in the AMN lesion which has not been previously described. Keywords: Influenza vaccine, Vasculitis, Acute macular neuroretinopathy, AMN, Optical coherence tomography angiography, OCT