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Gel
promises better vision for ageing eyes Indo-Asian
News Service
They predict that the pliant, jellylike material - injected through
a minuscule cut - could replace timeworn lenses that, scientists
speculate, harden over the years until, in mid-life, they lose their
ability to accommodate, or change focus, at arm's length. Beginning at about age 40, the condition, termed presbyopia - which
means "aging eye" in Greek -- becomes more pronounced, robbing
the lens of its youthful flexibility and visual acuity. To many members of
the 40-something set -- and nearly everyone older than 70 - near objects
appear as a blur. The team at Washington University in St. Louis thinks its patented
gel can clear up the problem, and tap into a $250-million market. "Our material should allow for focusing at any distance,
similar to the vision of a healthy 20-year-old," said researcher
Madalene Fetsch, graduate assistant in biomedical engineering at the
School of Engineering and Applied Science. The artificial lens could restore clarity to the hard-of-seeing,
including patients with cataracts, the vision-obstructing clouding of the
lens which affects an estimated one in seven seniors. "Cataract surgery is the most common surgery performed in the
United States today, especially in the over-65-year-old population,"
said Barrie Soloway, director of vision correction at The New York Eye and
Ear Infirmary in New York City. "Everybody over the age of 45 needs reading glasses, so the
market for this is huge." He estimated the technology could benefit
some 150 million Americans alone. "The accommodating intra-ocular lens could someday dominate
the cataract marketplace with a potential U.S. market of $250 million and
grow significantly more with worldwide acceptance provided that such an
implant is demonstrably efficacious, stable, safe and free of side
effects," said principal investigator Nathan Ravi, associate
professor of ophthalmology and visual sciences and professor of chemical
engineering at Washington University. Current treatments for presbyopia -- bifocals, special contact
lenses, surgery -- fall short of the wide-ranging capabilities of the
young human eye, he noted. "Presbyopia is corrected only partially by bifocals, a
treatment as old as Benjamin Franklin!" Ravi noted. Even patients who undergo the relatively new corrective laser
surgery often continue to need glasses for reading and up-close focusing,
scientists said. "It would be great if some day people had the option, at the
same time as having surgery, to remove their cataracts, to be able to do
away with corrective glasses and reading glasses or bifocals," Fetsch
said. "The potential for a material that would act like a young,
healthy, accommodating lens is incredible." In a significant step, her tests showed some promising similarities
between the gel and the natural lens, Fetsch reported at the 226th annual
meeting of the American Chemical Society in New York City. Fetsch and colleagues already have begun a process of refinement,
buoyed by the recent success of other scientists in improving the
refractive index in similar soft gels, called hydrogels. The three-dimensional networks of molecules swell but do not
dissolve in water, making them attractive for a wide range of applications
-- from thickening food and cosmetics to supporting drug delivery and
tissue replacement to composing artificial skin and extended-wear contact
lenses. "By creating a material that is soft, viscoelastic (springy
but viscous), dimensionally stable (no swelling), clear, non-toxic and
injectable, we should be able to replace the aging human lens with a
material that will act as a healthy young lens with a minimal surgical
procedure," said Ravi, who also serves as director of ophthalmology
at the Veterans Affairs Medical Centres. "We believe these gels are an important step towards creating
a better solution for those suffering from presbyopia." One advantage is only a very small injection hole -- too tiny to
require stitches -- is needed to place the lens material in the eye,
avoiding the common surgical technique of cutting a slit to insert a
replacement lens, Fetsch said. Copyright
© 2002 Global Action on Aging
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