Retinal studies at 446 torr in a hypobaric chamber.

This study was designed to see if retinal haemorrhage occurred after 24 h of decompression to a pressure of 446 torr. Four subjects were studied after 24 h of decompression and had retinal photography and fluorescein angiography performed at rest and following maximum exercise. No haemorrhages or fluorescein leakage was noted, even though the subjects experienced typical symptoms of acute mountain sickness and showed an increase in lung density-consistent with subclinical pulmonary edema. We conclude that 24 h exposure to 446 torr with a period of maximal exercise is an inadequate stress, either in time and/or degree, of hypoxia to produce retinal haemorrhage or leakage, as measured by flourescein.