Lasik surgery involves two basic steps: creating a corneal flap and reshaping the cornea according to prescription. Traditionally, the corneal flap during LASIK has been created with a microkeratome blade. It is well documented that a large part of the risks and complications from LASIK arise during the creation of the flap. Surgical techniques have been modified and instruments have been refined to improve the results and decrease complications, but nothing has made as significant an impact on improving LASIK as the IntraLase femtosecond laser.

This instrument utilizes an infrared laser and IntraLase software to create a corneal flap at a pre-programmed depth and position. As a low-pressure, soft suction ring holds the eye, the laser cleaves the corneal tissue at the predetermined depth forming bubbles of water and carbon dioxide at that plane. These bubbles connect to create a smooth surface that will become the interface between the flap and the corneal bed. The laser energy neither alters corneal curvature nor affects the prescription. There is no damage or change to the surrounding tissue.

The 3 to 5 micron laser spot size gives a very smooth separation with pinpoint accuracy. The IntraLase pattern zigzags the laser energy starting at the hinge and then continuing back and forth across the cornea. Finally, the laser cuts the edge of the flap circumferentially, leaving the hinge area untouched. The whole process takes approximately one minute per eye.

The obvious advantages of a flap created with IntraLase over a microkeratome are that there is little to no possibility of corneal abrasion, thin flap, thick flap, partial flap, incorrect diameter, or buttonhole flap. No one has ever gone blind or needed a corneal transplant with IntraLase. Furthermore, because the flap is of uniform thickness from center to edge (like a manhole cover), there is less chance of flap slippage or wrinkling if accidentally rubbed or bumped during healing after surgery. Also, because the resulting flap is of uniform thickness across the diameter, the IntraLase is ideal for far-sightedness, high amounts of nearsightedness, large pupils, moderate to high astigmatism, and small corneal diameters where producing a large enough flap for treatment far into the periphery is critical. Yet another advantage is the ability to create a very thin flap so as to maintain optimal corneal thickness when treating higher prescriptions or thinner corneas.

Because IntraLase programs the laser to produce flaps with vertical edges (again, like a manhole cover), it is more difficult for the outer layer of cells to migrate down under the flap into the interface since the length of the route for those cells is increased.

There are minor disadvantages of the IntraLase approach compared to the traditional microkeratome. Because the suction ring is on the eye for up to a minute, although at a relatively low pressure, there may be a greater chance of temporary eye redness on 5 percent of patients.

We have found that the advantages of using the IntraLase to create LASIK flaps far outweigh the possible disadvantages, and the IntraLase approach has brought LASIK surgery to a whole new level of safety and precision for our patients. Because we feel this is very compelling technology that significantly raises the standard for safety in vision correction surgery, we are recommending the IntraLase approach for ALL our qualified patients.

• Intralase® VS. Microkeratome Statistics
• Intralase® Patient Information
• Intralase® Movie from IntraLase.com

Pros

• Flap thickness and diameter is programmed into the laser and more predictable than a microkeratome
  • Flap thickness can vary ± 14 microns
  • Flap thickness is consistent across the flap diameter
  • Flap diameter is very predictable
• Accuracy is particularly beneficial for patients with
  • Thin corneas preoperatively
  • High degrees of correction
  • Large pupil that dilates more than average at night and in dim light
• Safer with fewer complications than bladed Lasik flap production
  • No significant epithelial injury or damage
  • No free flaps
  • No partial flaps
  • No thin or thick flaps
  • No buttonhole flaps
  • No perforation of the eye
• Result is either a “perfect flap” or “no flap”
  • Serious vision threatening complications not been seen in over 100,000 cases and rising
• More comfortable
  • Low vacuum
  • No sound during procedure
• More accurate visual results for most corrections

Cons

• Procedure takes more time (one minute per e vs. 30 seconds per eye with a keratome blade
• Eyes can be “red” for a few days longer than with bladed keratomes
• Visual recovery can be slower b 1 to 3 days

Better vision1	YES
Better safety2	YES	—
Highest degree of precision and predictability3	YES	—
Individualized flaps3	YES	—
Fewer retreatments4	YES	—
Ability to be used in more eligible patients2	YES	—
Patient preferred5*	YES	—

IntraLASE.com : The New Shape of Vision
National Science Foundation : Laser "Scalpel" Improves Popular Eye Surgery
National Science Foundation : Laser Eye Surgery Pioneers Earn International Honors

Articles (Scientific Studies):

Durie – “Laser vs. Manual Keratectomy” March 2004 Cataract & Refractive Surgery Today
Kurtz – “The Story of Intralase” May 2002 Cataract & Refractive Surgery Today
Binder – “Flap dimensions created with the Intralase FS Laser” May d002 Cataract & Refractive Surgery Today
Kezirians-Stovecipher – “Comparison of Intralase Femtosecond Laser and Mechanical keratomes for Laser-Insitu-Keratomileusis" 2004 ASCRS