Positive Black Out
In 1951, Thomas Duane was stationed at the Naval Air Development Center - home of the Johnsville human centrifuge. The centrifuge had been installed the year before and was the world’s most powerful tool for studying the effects of g-forces on the human body. Pilots can black out while experiencing positive g-forces during flight. Duane’s study determined why this happened and documented “greyout,” when vision is dimmed, and peripheral vision lost before a pilot blacks-out or faints due to loss of blood pressure. Emil Bethke was then brought in to illustrate Duane’s findings. It would be 15 years before a fundus camera was mounted to the centrifuge to photograph the phenomenon.
Thomas Duane, MD (1917-1993)
The centrifuge remained in use for almost 50 years as part of training for pilots and astronauts. John Glenn recalled, “[In the centrifuge] you were straining every muscle of your body to the maximum…if you even thought of easing up, your vision would narrow like a set of blinders, and you’d start to black out.”
Bethke's Retinal Illustrations
According to Duane, medical illustrator Emil Bethke spent only “about a week” with the study “but during that time rode the centrifuge time and time and time again, which was a huge undertaking in itself, until he finally was able to see the changes going on in the subject’s eyes.” Afterwards, Bethke produced nine illustrations for Duane.