The complex immunological mechanisms of vaccines bring about an inevitable risk of immune-mediated adverse reactions. Of special interest in this time of epidemic is the safety of COVID-19 vaccines and, in particular, the emerging evidence that the ChAdOx1 nCoV-19 adenoviral vector vaccine from AstraZeneca can cause vaccine-induced immune thrombotic thrombocytopenia (VITT). We present the case of a patient who developed an acute paracentral scotoma after having received this vaccine.