Both Femtosecond Laser LASIK Flaps (Intralase) and Mechanical LASIK Flaps show equal safety in a recent study of effect on the corneal endothelium 5 years after LASIK. There continues to be debate as to whether there is a safety advantage to LASIK flaps made with a laser (such as the Intralase in the “all laser LASIK” procedure) compared to LASIK flaps made with the mechanical microkeratome.
One important measure of the safety of flap creation in LASIK is the effect on the corneal endothelium. The corneal endothelium is a layer of cells on the back surface of the cornea. You are born with your life time’s allotment of corneal endothelial cells. If they are lost, your body cannot make new ones.
The LASIK flap is made on the outer surface of the cornea. A theoretical concern would be any damage created during flap creation on the delicate corneal endothelial cells on the inner surface of the cornea. The safest flap technique would not create endothelial cell injury. A recent study looked at the effect on these endothelial cells of flap creation during LASIK with two techniques: a laser flap and a mechanical flap.
A prospective, randomized study was conducted which included 21 patients with a mean age of 38 years and with myopia with or without astigmatism. Patients underwent LASIK with the mechanical microkeratome in one eye and with the femtosecond laser flap in the other eye of the same patient. The corneal endothelium was evaluated pre-operatively and 3 and 5 years post-operatively.
Results showed similar endothelial cell densities at 5 years in the femtosecond laser flap group and the mechanical microkeratome flap group. Mean endothelial cell loss was 0.8% in the femtosecond laser group and 0.4% in the mechanical microkeratome group, which was not felt to be a statistically significant difference.
Interestingly, this study confirms the essentially equal safety of both the femtosecond laser flap technique and mechanical microkeratome flap creation in terms of their effects on the corneal endothelium. It should be noted by comparison, however, that ongoing contact lens wear can have a long term and irreversible damaging effect on the corneal endothelial cells.
See Also
Bladeless LASIK: Creating A LASIK ap With Precision
All About Vision Summary of the benefits of using a femtosecond laser to create LASIK flaps.
Femtosecond Laser-Assisted Corneal Flap Cuts: Morphology, Accuracy, and Histopathology
A medical journal article reviewing laser created LASIK flaps.
Femtosecond Laser LASIK Flap Settings and OBL
A video discussion of the opaque bubble layer which can be encountered in LASIK flap creation with the femtosecond laser.
Femtosecond Laser versus Mechanical Microkeratome: A Retrospective Comparison of Visual Outcomes at 3 Months
A comparison of visual outcomes at 3 months between all-laser LASIK and LASIK using a mechanical, bladed, microkeratome.
Corneal Endothelial Cell Changes 5 Years After LASIK: Femtosecond Laser versus Mechanical Microkeratome
A comparison of the effect on the corneal endothelial cell layer of different methods for making the flap in LASIK laser eye surgery.
Femtosecond Laser Versus Mechanical Microkeratome LASIK flaps
This author prefers the mechanical microkeratome for flap creation in LASIK laser eye surgery over the femtosecond laser flap technique.