Fig. 1: Bruch membrane opening (BMO) and height.

a Marking of the BMO (orange marker) is shown on 1 radial section through the optic nerve head. The BMO center (red dashed line) was used to determine the location for a reference plane at 2 mm (white line), from which the BMO height was quantified (blue line). b The BMO height is recessed in pre-flight optical coherence tomographic (OCT) scans compared with healthy controls. This difference increases after long-duration microgravity exposure. It should be noted that most astronauts included in this study had previous spaceflight experience. (Reprinted with permission from Patel et al.87).