Correlating increased ocular and systemic blood pressures with neuroretinal function.

BACKGROUND

The microgravity environment of spaceflights alters the systemic circulation, decreasing the peripheral resistance, while increasing the heart rate and systemic blood pressure.

HYPOTHESIS

Body orientation simulating fluid shifts associated with microgravity during spaceflights affects the neural retinal function.

METHODS

Fifteen healthy adults between 18 and 26 yr of age participated in this study. Scotopic flash electroretinograms and oscillatory potentials were compared for: 1) baseline, wherein subjects were declined 30 degrees from vertical; and 2) for microgravity simulation where subjects were in a 7 degrees head down tilt for 90 min.

RESULTS

Group averaged implicit times 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 short duration may cause retinal ischemia manifest as neuroretinal dysfunction with yet undetermined effects on visual and overall performance.