<p>Spaceflight-associated neuro-ocular syndrome (SANS) is a disorder primarily characterised by changes in the eye and optic nerve, but changes in brain features are also noted after spaceflight. SANS is caused by exposure to prolonged microgravity and at least one feature of SANS has been reported in 81% of National Aeronautics and Space Administration (NASA) astronauts. Early clinical features of SANS are observed in almost all individuals undergoing spaceflight, with the condition exacerbated by the duration of spaceflight. Knowledge of the features of SANS and the aetiology has rapidly grown since its first description in 2011. As international space agencies plan exploration beyond low Earth orbit and with the expansion of the commercial space sector, a publicly available consensus guide on diagnosis and potential management would be instructive to flight surgeons who manage SANS. Harmonising case identification will not only enhance clinical management but is also vital to set a framework for research into SANS. Here we collate and interpret the up-to-date phenotyping and clinical insight in SANS, with expertise from the leading SANS experts at NASA. A consensus on diagnosis and management with countermeasures is detailed. Space exploration is a rapidly evolving field and consequently, insights into SANS will undoubtedly grow and allow us to further refine our understanding of this condition.</p>