Atomic Force Microscopy was used in a study to compare the quality of the LASIK flaps made with the femtosecond laser and mechanical microkeratomes. The first step in LASIK is the creation of a flap. Two approaches to making the LASIK flap are in widespread use in the United States and internationally: 1) using a femtosecond laser such as the Intralase (also known as iLASIK or “all laser LASIK” or “bladeless” LASIK) and 2) using a mechanical microkeratome (also known as “bladed” LASIK). Both the laser and the mechanical approach to creating LASIK flaps have undergone significant evolution from earlier generations of each approach and both work well in their latest formats. There continues to be debate as to the advantages and disadvantages of laser flaps compared to mechanical microkeratome flaps.
The two approaches to flap creation use very different strategies. The femtosecond laser places laser pulses into the cornea directly at the desired depth. Each pulse creates a rapidly expanding plasma bubble of exploding gas, which forces the cornea to separate into a flap. The mechanical microkeratome, by contrast, acts more like a spatula to glide between the layers of the cornea to lift up a pre-existing layer as a flap.
A recent study using a very powerful tool called the “atomic force microscope” was performed in Italy to examine the quality of the surface of the interface between the cornea and the flap to compare the two approaches. The atomic force microscope has certain advantages over using the electron microscope for this purpose. The study also looked at the role of laser spot energy and laser spot separation on the quality of the corneal surface with femtosecond laser LASIK flaps. The researchers found that larger, more powerful laser bursts produced a more bumpy surface with more variation that seen with smaller, less powerful, but more numerous laser bursts or with the mechanical microkeratome. The highest quality, most smooth, corneal bed and LASIK flaps were seen with either the mechanical microkeratome (“bladed”) LASIK or with very low energy, small femtosecond laser spots. Current femtosecond lasers such as the Ziemer (“Z-LASIK”) are moving in the direction of smaller, lower energy spot sizes in at attempt to match the quality of mechanical microkeratome smoothness. The Intralase (“iLASIK”) has also been using smaller, lower energy spots throughout its evolution over the past few years.
See Also
Optimal Parameters to Improve the Interface Quality of the Flap Bed in Femtosecond LASIK
A study showing the effect of bubble size and laser energy level on the LASIK flap when created with the femtosecond laser.
Mechanical Microkeratome versus Femtosecond Laser
A debate about the relative merits of two methods of LASIK flap creation — with the mechanical microkeratome versus with the femtosecond laser.
Femtosecond Laser-Assisted Corneal Flap Cuts: Morphology, Accuracy, and Histopathology
A scientific review of the characteristics of LASIK flaps created with the femtosecond laser.
Bladeless LASIK: Creating a LASIK Flap With Precision
All About Vision discussion of the benefits of using the femtosecond laser to create LASIK corneal flaps.
Flap and Interface Complications in LASIK
A discussion of surgical and medical management of LASIK complications involving the flap and the interface between the LASIK flap and the corneal bed.
Characterisation of corneal fibrotic wound repair at the LASIK flap margin
A British Journal of Ophthalmology review of healing at the edge of the LASIK flap.