IntraLase: Creating a LASIK Flap with Precision
By Keith Croes; updated by
Marilyn Haddrill;
reviewed by Dr. Vance Thompson
A newly developed technology called IntraLase appears to enhance the
safety of LASIK vision correction by using laser energy instead of a
microkeratome,
a cutting tool with a metal blade used in traditional LASIK procedures.
In LASIK, the
microkeratome is used to cut a hinged flap in the cornea. The flap gets folded
back, and an excimer laser is used to remove (or "ablate") some tissue from the
newly exposed surface. Then the flap is put back in place, resulting in a reshaped
cornea that produces better vision.
With IntraLase, a special laser is used instead of a blade to create the flap.
Then the usual excimer laser does the ablation.
So in the IntraLase procedure, two different lasers are used, which is why
LASIK surgeons sometimes call it "bladeless" or "all-laser" LASIK.
As in typical LASIK, the flap then is replaced to serve as a type of natural
"bandage" for healing.
Advanced Medical Optics (AMO) in 2007 acquired IntraLase, which was integrated
into the company's CustomVue excimer laser platform. The new system now is marketed
as iLASIK.
Considering Complications: Blade Versus Bladeless
While LASIK complications are relatively rare, they are sometimes
associated with the oscillating blade used with traditional microkeratomes.
Metal blades might create uneven flap edges, resulting in abnormal corneal
surfaces and vision defects such as irregular astigmatism.
Metal blades also
have been associated with formation of incomplete or improperly formed
"buttonhole" flaps that can cause vision-threatening scars. Many
eye surgeons report these types of complications are far less likely
with laser-created flaps.
As a replacement for microkeratomes, IntraLase creates flaps through
infrared laser energy that inserts a precise pattern of tiny, overlapping
spaces just below the corneal surface. The IntraLase laser operates at
extremely high speeds (pulses of one quadrillionth of a second), allowing
tissue to be targeted and divided at a molecular level without heat or
impact to surrounding tissue.
Studies indicate that IntraLase is associated with significantly fewer
overall LASIK complication rates. Nevertheless, eye surgeons recently
have reported one postoperative complication of unusual light sensitivity
such as photophobia that appears unique to the use of the IntraLase in
LASIK.
Published reports mention this complication has occurred in as
few as 1 percent or as many as 20 percent of patients undergoing LASIK with IntraLase,
according to an article in Review of Ophthalmology, October 2004. (The 20
percent
figure was reported by one surgeon, whose IntraLase laser was replaced by the
company because compared with other surgeons' experiences, the figure
was abnormally high, according to the article.)
However, many eye surgeons report that the photophobia complication
is temporary and can be resolved with steroid treatment (eye drops) lasting
a few weeks. Eye surgeons favoring IntraLase emphasize that light sensitivity
is a transient side effect that soon resolves, unlike more serious and potentially
permanent vision-threatening complications that might result from defective flaps.
However, the tradeoff for potentially increased safety with the use of IntraLase
is accompanying additional LASIK procedure costs of about $300 per
eye, according to Review of Ophthalmology. [Read our LASIK
cost article for other price estimates for IntraLase LASIK.]
Usually patients are
given the choice of whether they prefer LASIK flaps to be cut
with a blade or with the more expensive laser technology, but some surgeons may prefer
to use only IntraLase and may bundle that cost into their overall LASIK fee. [Read a
blade vs. bladeless LASIK debate.]
How IntraLase Works
The LASIK surgeon uses computer software to guide the
IntraLase laser beam, which applies a series of tiny (3-micron-diameter)
bubbles within the central layer of the cornea. The resulting corneal flap
is created at a precise depth and diameter pre-determined by the surgeon.
As occurs with a mechanical microkeratome, a small section of tissue at
one edge of the flap is left uncut, forming a hinge that allows the surgeon
to fold back the flap so that the cornea can be accessed and reshaped for vision correction.
[See a slide show of how LASIK works.]
Comparing IntraLase with Traditional LASIK: The Difference Is in the Corneal Flap
With IntraLase, people with thin corneas who once were unsuitable for
LASIK may now be candidates. Most people have corneas that are between 500 and 600 microns
thick, and most microkeratomes cut flaps ranging between 100 and 200 microns thick.
Because of its precision, the IntraLase appears capable of more reliably and
consistently producing corneal flaps as thin as 100 microns.
This means surgeons now have more options to perform LASIK in people with
thinner and flatter corneas, according to Vance Thompson, MD, a
Sioux Falls, S.D., refractive surgeon with experience using IntraLase.
[Dr. Thompson is also an AllAboutVision.com Advisory Board member.]
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