Creating a LASIK Flap with Precision
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.
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.
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.