Newswise — Increasing stiffness of
the aging eye may make older adults more susceptible to eye damage
following trauma, according to research at Wake Forest-Virginia Tech
School of Biomedical Engineering and Sciences.
“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 University School of Medicine,
a part of Wake Forest University Baptist Medical Center. And the
researchers called for design modifications to reduce the risk that
a deploying air bag in an automobile will contact the eye.
People who wear glasses “should be
sure that they are fitted with impact-resistant polycarbonate
lenses,” he said. “Those in sports or work environments requiring
protective lenses should wear them.”
Stitzel and his colleagues have
been working on the computer simulation model for several years and
already have reported that the model tracks the actual results of a
series of experiments in which foam particles, BBs and baseballs
strike the human eye. The model predicts when the globe of the eye
will rupture from high-speed blunt trauma.
In an accompanying editorial, Paul
F. Vinger, M.D., of Concord, Mass., said the Virginia Tech-Wake
Forest center’s project to create the computer simulation “is a
formidable undertaking that is bound to change the course of eye
trauma research.”
He said that when the model
predictions were compared with actual results, there was “excellent
correlation between the calculated and experimental results.”
The new research “extends this
model to study the effects of increasing lens stiffness due to aging
on the probability of suffering eye injuries in a car accident, such
as being hit in the eye with the steering wheel, an airbag or a foam
particle,” Vinger said in the editorial.
About Wake Forest University
Baptist Medical Center: Wake Forest Baptist is an academic health
system comprised of North Carolina Baptist Hospital and Wake Forest
University Health Sciences, which operates the university’s School
of Medicine. The system comprises 1,187 acute care, psychiatric,
rehabilitation and long-term care beds and is consistently ranked as
one of “America’s Best Hospitals” by U.S. News & World Report.
