Award-Winning Human Eye Model Gages Risks Of Military Helicopter Airbag Use

BLACKSBURG, Va., June 9, 2003 – Airbags, which have been saving the lives of automobile passengers for several years, are now planned for use in military helicopters. One concern about this use of airbags is the risk of eye injuries among pilots who may be wearing night vision goggles when airbags deploy, and engineering researchers at Virginia Tech have developed a computer model that can evaluate the potential for such injuries.

Erik Power, a Virginia Tech mechanical engineering (ME) graduate student at the time, was the lead researcher in development of the human eye model, which includes surrounding structures such as fatty tissue, extra-ocular muscles and the bony orbit (eye socket).

Power and his research collaborators were selected by the Army Aviation Medical Association for the Joseph Haley Writing Award, which annually recognizes the best paper published in the field of helicopter aviation medicine. The paper, "Computer modeling of airbag-induced ocular injuries in pilots wearing night vision goggles," was completed as Power's master's thesis in 2001 and published in the October 2002 issue of Aviation, Space, and Environmental Medicine, the official journal of the Aerospace Medical Association.

The researchers used their model to determine the worst-case position of a helicopter pilot wearing night-vision goggles during airbag deployment. They discovered that the worst-case position entailed a minimal distance between the eyes and goggles, with the subject looking directly toward the airbag and making initial contact with the airbag halfway through its full deployment.

Simulations that Power and his colleagues performed with the ocular model included leaving the goggles fastened to the virtual pilot and having the goggles break away. They also placed a protective lens in front of the pilot's eyes, which they found reduced the stress of impact but increased the force on the surrounding orbital bones.

The paper's co-authors are Stefan Duma, ME associate professor and Power's adviser on the project; ME student Joel Stitzel; Ian Herring, assistant professor of veterinary medicine at Virginia Tech; ME associate professor Robert West; Cameron Bass, assistant professor of ME at the University of Virginia; and Col. John Crowley and Fred Brozoski of the U.S. Army Aeromedical Laboratory in Fort Rucker, Alabama.

The results of this project provided the foundation for a multi-year research program that evaluated the risk of ocular injuries to military aviators. By using the computer model, the researchers were able to reduce the number of costly physical experiments. The project was funded by the Army's Aeromedical Laboratory.

Power, who completed his master's degree in ME with an option in biomedical engineering in 2001, now works in the area of crash safety for the National Highway Traffic Safety Administration in Washington, D.C. He earned his bachelor's degree in ME at Virginia Tech magna cum laude in 2000 and received Pratt fellowships in support of his graduate research at the university.