Implantable contact lenses
eliminate hassles of regular contacts
BY MITCH LESLIE
What's the most irksome
part of wearing contact lenses? Scouring the bathroom
floor on hands and knees for an errant lens? Waking from
a nap to find that a contact has fused to the inside of
your eyelid? The monotonous hygienic routine?
Soon, surgically
implanted, permanent contact lenses that never need to be
removed or cleaned may banish these and other annoyances.
Stanford ophthalmologist Edward E. Manche, MD, is
participating in a national trial of an implantable
contact lens to correct nearsightedness. The lens fits
inside the eye, just in front of the pupil.
Stanford is one of 10
sites around the country evaluating these lenses, which
have been used in Europe for more than a decade, said
Manche, an assistant professor of ophthalmology. Evidence
from this round of clinical trials will be submitted to
the Food and Drug Administration, which will then decide
whether the lenses are safe and effective enough for
general use.
The clear, oblong implants
are about the size of the tip of your pinky and are made
of the same plastic used in replacement lenses for
patients with cataracts.
The current trials are
testing how well the lenses work in patients with
moderate to extreme nearsightedness. Manche said the
implants could be particularly useful for people with
extreme nearsightedness because their vision problem
often is too severe to be corrected with laser eye
surgery. They must either wear very thick, distorting
glasses, which limit peripheral vision, or resort to
contacts, which many people find too bothersome to stick
with.
The implant surgery is
quick and painless, lasting about 20 minutes. After
numbing the eye with anesthetic drops, Manche inserts the
lens through a small incision in the cornea -- the clear,
dome-shaped "front window" of the eye -- and
then centers it over the pupil. A tiny clip at each end
of the implant clamps it to the iris, the colored part of
the eye. Modeled on a lobster's claw, the clips keep the
implant from drifting out of position over time.
Because of the risk of
infection, Manche performs the surgery in a sterile
operating room in Stanford Hospital. Patients usually
receive a mild sedative to reduce anxiety during the
operation, and they can go home immediately afterward.
Improvements in vision are
usually apparent immediately after the surgery, Manche
said. Earlier studies found that 92 percent of patients
gained vision of 20/30 or better within a month, Manche
said. Vision of 20/20 is considered excellent, while
20/40 is the cutoff for driving a car without wearing
corrective lenses.
Besides infection,
possible complications include inflammation, increased
pressure in the eye and cataracts. Earlier studies have
shown that all of these are rare, Manche said. The
plastic used to make the implants has a 50-year track
record of safe use in the body, he added.
Because the treatment is
still considered investigational, only patients who join
a clinical trial can obtain it. Volunteers with moderate
to extreme nearsightedness -- between - 5 and - 22
diopters on their eyeglass prescription -- are still
needed to participate in the trials at Stanford. Patients
will have to pay the costs of surgery, around $ 3,500 per
eye. For more information, contact Leslie Lyssenko,
program director at the Stanford Eye Laser Center, at
(650) 498-7020. SR
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