Oh great, another fancy word, another new procedure, more promises
to fix my eyes without glasses or contacts! Well, sorta. The ICRS
is an old fashioned plastic that is used in a very modern way.
I'm talking about twin semi-circles of optically clear PMMA, or
polymethylmethacrylate plastic. Remember the original HARD contact
lenses? This is the same stuff but shaped as tiny arcuate wedges
that are actually inserted WITHIN the corneal tissue under topical
anesthesia (drops). Two of the most appealing features of this
procedure are one: the process is reversible; and two: there is
NO alteration of the central cornea.
As you all know by now, the excimer laser procedures remove or
ablate tissue near the center of the cornea. The ICRS procedure
does not touch the center cornea but rather skirts around the
central zone. This pays dividends in regard to speed of recovery.
The surgeon creates a 1.8 mm long incision that is ¾ mm in
depth which forms a pocket in the stroma of the cornea. Depending
on the amount of correction needed, from 1 to 5 diopters, a certain
thickness of plastic is selected (the thicker the piece, the more
nearsightedness that can be fixed) and inserted in the channels
created in the stroma. By this "stretching" of the cells
in the peripheral cornea it produces a "tautness" which
essentially flattens the central corneal, thereby producing less
myopia.
Visual recovery is rapid and stable. According to Dr. Daniel Durrie,
an investigative surgeon, "the best corrected visual acuity
is better one day postop with the ICRS than we have seen with
any other procedure. That may be because there isn't any surgery
in the center of the pupil." The PRK laser procedure, in
contrast, may result in hazy or blurry vision for up to a week
or longer. The LASIK procedure fairs better in recovery but it
may still take up to 3 or 4 days for vision to stabilize. "Adjustability,
rather than reversibility, is the ICRS's strong suit," Dr.
Durrie suggested. "There isn't any change in the refraction
after a week or so, so we're putting the ring in and if someone
doesn't get exactly what he or she wants, then we'll change it,"
Dr. Durrie said. "Adjustability is really the key to it."
Imagine your vision being corrected to 20/20 after ICRS surgery
only to have it slip to say 20/50 in a year or so. This is unlikely
but in that event, it may become possible to remove the inserts,
replace them with thicker segments and regain your 20/20 in a
matter of minutes.
The ICR device is manufactured by KeraVision, Inc. of Fremont, California. FDA investigational studies are ongoing but the results to date have been quite promising. In one early study involving 50 patients, 26% were 20/16 or better; 54% were 20/20 or better; 76% were 20/25 or better; and 96% were 20/40 or better, and this was one day postop. At two weeks, 50% were 20/16 or better; 72% were 20/20 or better; 84% were 20/25 or better; and 94% were 20/40 or better. At one month, 63% were 20/16 or better; 82% were 20/20 or better; 88% were 20/25 or better; and 98% were 20/40 or better.
These are excellent statistics for refractive surgery but one
must remember that the sample was relatively small and the amount
of myopia treated was low to moderate with no astigmatism.
So, the ICR system certainly sounds intriguing, doesn't it? Watch
for new developments in this technology to even correct farsightedness
and astigmatism.