CORRELATING INCREASED OCULAR AND SYSTEMIC BLOOD PRESSURES WITH NEURORETINAL FUNCTION

Background: The microgravity environment of spaceflights alters the sy stemic circulation, decreasing the peripheral resistance, while increa sing the heart rate and systemic blood pressure. Hypothesis: Body orie ntation simulating fluid shifts associated with microgravity during sp aceflights affects the neural retinal function. Methods: Fifteen healt hy adults between 18 and 26 yr of age participated in this study. Scot opic flash electroretinograms and oscillatory potentials were compared for: 1) baseline, wherein subjects were declined 30 degrees from vert ical; and 2) for microgravity simulation where subjects were in a 7 de grees head down tilt for 90 min. Results: Group averaged implicit time s for the ERG b-wave, as well as OP3, OP4 and OP5 were prolonged after microgravity simulation, and the group averaged OP index was reduced. Conclusions: The results suggest that microgravity of relatively shor t duration may cause retinal ischemia manifest as neuroretinal dysfunc tion with yet undetermined effects on visual and overall performance.