"The gradual change in lens stiffness during a person's lifetime leads to a lens that is four times stiffer than at birth, and this has implications for the likelihood of eye injury," said Joel D. Stitzel, Ph.D., of the Virginia Tech-Wake Forest Center for Injury Biomechanics, and three colleagues, writing in the June issue of Archives of Ophthalmology.

Using a computer model of the eye, Stitzel and colleagues investigated possible injury mechanisms in the eyes of elderly individuals and the effects of lens stiffness on injury prediction by the model. The new data document that the risk of certain types of eye injury increases with age.

"General testing of the mechanical characteristics of the entire lens suggests that aging of the human lens is associated with a progressive loss of mechanical strength," Stitzel said. "As stiffness of the lens increases over time, the amount of deformation that the lens can withstand without damage or dislocation decreases. This can result in an increased risk of eye injury with age, not only to the lens itself but also to other internal components of the eye, resulting in increased risk of tearing of internal structures of the eye and bleeding." He added, "The effect is like brittle bones in some elderly people and those with osteoporosis: just as these people are more prone to breaking bones, increased lens stiffness can result in greater risk of injury to the eye."

This evidence led to several recommendations.

"The data indicate that all people, especially elderly individuals, should use safety systems, such as seat belts, while driving a car and sit as far back from the air bag as is comfortable," said Stitzel, assistant professor of biomedical engineering at Wake Forest Univer
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Contact: Robert Conn
rconn@wfubmc.edu
336-716-4587
Wake Forest University Baptist Medical Center
23-Jun-2005