NASA astronaut Scott Kelly (left) assists Japan Aerospace Exploration Agency (JAXA) astronaut Kimiya Yui (right) with measurements for the ongoing Ocular Health study. Yui is seen operating a device called a Fundoscope which is used to take images of the retinal surface of an astronaut's eye. Ocular Health is gathering data on crew visual health during and after long-duration space station missions to characterize how living in microgravity can affect the visual, vascular and central nervous systems.