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Corneal Inlays and Corneal
Onlays:
Corneal inlays and onlays
are made of biocompatible
materials that closely
resemble the clear surface
of the eye itself. And if
current and future clinical
trials prove successful,
these devices may soon
represent a new form of
vision correction surgery.
In LASIK and PRK, vision
correction is achieved when
laser energy reshapes the
cornea to alter the way
light rays enter the eye.
But with corneal inlays or
onlays inserted just beneath
the eye's surface, laser
energy some day could be
used to sculpt this
artificial material instead
of the eye itself.
Even without laser
reshaping, corneal inlays or
onlays alone also may work
much like contact lenses to
provide vision correction.
Unlike contact lenses,
however, these devices never
require regular removal or
ongoing care. And they
differ from surgically
implanted lenses because
they are not placed behind
the cornea. Also, a corneal
inlay or onlay is designed
to seamlessly "merge" with
the eye's surface.
Through use of inlays and
onlays for vision
correction, eye surgeons may
avoid complications
sometimes associated with
procedures such as LASIK,
PRK, and implantable lenses
because the eye's natural
surface tissue is left
virtually undisturbed.
While the technology is not
yet approved by the FDA,
clinical trials began in
early 2006 for one device
created by AcuFocus (Irvine,
Calif.), which has formed a
business alliance with
Bausch & Lomb (Rochester,
N.Y.).
The ACI 7000 is a corneal
inlay used for presbyopia
correction. (Image provided
by AcuFocus of Irvine,
Calif.)
This corneal inlay, known as
the ACI 7000, is designed to
correct near vision focusing
problems caused by aging, a
condition known as
presbyopia. With this inlay,
a thin flap is created on
the eye's surface where the
device is applied. The flap
then is replaced over the
inlay to hold it in place.
The procedure takes less
than 15 minutes and can be
performed in the eye
surgeon's office. Sutures
are not required, and only
topical anesthesia in the
form of eye drops is used.
According to Bausch & Lomb,
the inlay is designed to
block certain light rays
reflecting from near objects
that ordinarily would not be
focused correctly by the
presbyopic eye.
"Its optical principle is
the pinhole phenomenon,
which when used in
photography (in terms of a
small aperture), allows
depth-of-focus and thus
allows clear vision at all
distances - near,
intermediate, and distance.
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