There appears to be a fundamental difference between LASIK flaps cut either with a blade or created with a laser. Laser created flaps mean a safer surgery as the results are more accurate, so fewer enhancements needed, and the cornea is left stronger.
Making a replaceable flap is the first part of the LASIK procedure, just prior to reshaping the cornea to correct vision. Until recently (and still in some clinics) the flap was made by a physical cut with a sharp razor blade contained within a precision device. However several clinics and the major three chain operators have invested in femtosecond lasers to create the corneal flap without the need for a blade.
This is known as blade-free LASIK, dual laser LASIK, Z-LASIK or IntraLASIK depending on which clinic you are talking to.
We know that thicker flaps cut with a blade do not fully heal and can be lifted up surgically even many years later. Traditional blade flaps are thicker and cut deeper into the cornea. Laser flaps are thinner and leave the eye stronger afterwards.
However a key difference highlighted by Professor John Marshall in London is that because these very thin laser flaps pass through near the surface of the cornea where the collagen is different from deeper down, they actually heal down and are not able to be lifted later on. This means the eye regains strength again with a thin laser flap, but not with a blade flap.
Newer blade machines have been introduced in 2008 and 2009 that cut thinner flaps to compete with the thin femtosecond laser flaps which should benefit from the better healing seen in sub-120 micron flaps
My recommendation to you when choosing a clinic is to be able to select to have a femtosecond laser procedure at a clinic that has that technology. They are more expensive than blade procedures (expect to pay around £300 more per eye) but well worth the likelihood of a long-term increase in safety.
About the Author: Mr. Dave Allamby FRCS FRCOphth is a leading London-based laser eye surgeon. You may have seen him on the This Morning TV show with Phillip Schofield and Fern Britton or read one of several articles in the national press, recently for treating Denise Van Outen, rock giant Rick Wakeman and broadcaster Paul Ross. David is Medical Director at Focus Laser Vision, known as a world-leading clinic in the treatment of presbyopia, or age related loss of close vision. Focus Laser Vision is also London's only clinic to offer next-generation Z-LASIK laser eye treatment for short sight, long sight or astigmatism.