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[YOUR NAME HERE] thought you might be interested in this story from the University of Rochester.
MEDIA CONTACT: Tom Rickey, (585) 275-7954, or David Williams, (585) 275-8672
September 30, 1994
Sharpest Pictures of Human Retina
University of Rochester scientists have taken the sharpest
pictures yet of the inside of the living human eye, making
visible for the first time the individual cells called cones.
Such precise images may one day help doctors treat several types
of eye disease.
Scientists took pictures of the cones -- the photoreceptors
that allow us to detect color and see clearly during the daytime
-- in six people by shining a low-power laser through the pupil
and onto the retina. The retina reflected the light back to an
electronic camera outside the eye.
Graduate student Donald Miller will describe the work at the
annual meeting of the Optical Society of America Monday, Oct. 3
in Dallas. Miller worked with David Williams, professor of
psychology and director of the University's Center for Visual
Science, and G. Michael Morris, professor at the Institute of
The retina is like a screen inside the eyeball that captures
light signals and transmits them to the brain. It's also the only
part of the living brain that scientists can view directly.
Though the retina is about the same consistency as wet single-
ply tissue paper, it is packed with photoreceptors (both cones,
for color and resolution, and rods, for night vision) that allow
us to see. Light absorbed by our cones and rods is converted into
electrical signals that the brain puts together to form images.
The team saw individual cones, which are about 3 microns
wide. The instruments that ophthalmologists currently use see
structures no smaller than about 10 microns.
Seeing individual photoreceptors inside human eyes could
help doctors detect or treat several types of eye disease,
including age-related macular degeneration (AMD), which affects
hundreds of thousands of Americans and is the leading cause of
blindness in the elderly, and retinitis pigmentosa, which causes
the photoreceptors to grow abnormally long and afflicts thousands
of people in the U.S., causing gradual deterioration of the
retina and eventual blindness.
A key to the experiment was a special electronic camera that
is many times more sensitive than photographic film. The camera
also has high resolution, dividing a square area on the retina
just one-third of a millimeter wide into more than a quarter of a
million pixels. The team dilated each subject's pupils with eye
drops and carefully corrected the major optical defects that
everyone's eyes -- even people with 20/20 vision -- contain.
With corrective lenses in place, Miller and colleagues shot
a low-power (.3 milliwatts, well below safety level) beam of
yellow light from a dye laser into the eyeball for just a
fraction of a second.
"It's a lot like taking a flash picture," says Miller. "You
need the flash to illuminate the subject, which in this case is
the retina. The effect on the subject is the same as that of a
powerful flash from a camera -- they see a bright flash that
causes an after-image for a few seconds."
The team hopes to get even better images by using the same
"Star Wars" technology that helps telescopes and missiles see
through the atmosphere to correct for more complex aberrations
present inside everyone's eyes.
"The conventional wisdom is that the eye's optics are too
poor to let you see individual receptors," says Williams. "We've
shown that this is not true. These pictures offer considerable
promise for what we might see in the future with even better
About the University of Rochester
The University of Rochester (www.rochester.edu) is one of the nation's leading private universities. Located in Rochester, N.Y., the University gives students exceptional opportunities for interdisciplinary study and close collaboration with faculty through its unique cluster-based curriculum. Its College of Arts, Sciences, and Engineering is complemented by the Eastman School of Music, Simon School of Business, Warner School of Education, Laboratory for Laser Energetics, Schools of Medicine and Nursing, and the Memorial Art Gallery.