Retinal Vascular Response to Hyperbaric Oxygenation

Hyperbaric oxygenation increases both the tension and concentration of oxygen in blood to levels far in excess of that obtained by any other means.1,2The resultant increase in oxygen delivery to tissues may correct or prevent hypoxic damage if the ischemic organs are adequately perfused.3Central nervous system tissue is especially vulnerable to hypoxic damage and improved oxygenation due to hyperbaric exposure would be of great clinical value. However, previous studies indicate that cerebral blood flow decreases during the respiration of pure oxygen.4As a result, cerebral venous blood is incompletely oxygenated, despite increases in arterial blood oxygen tension to values in excess of 2,100 mm Hg.2In order to further evaluate this problem, the retinal vasculature of normal subjects was photographed and measured during exposure to both increased atmospheric pressures and hyperoxia in a hyperbaric chamber. The retinal portion of the cerebral circulation is easily