SAFETY NOTE: Does the LASIK flap ever heal?
IMPORTANT NEWS for those people considering having LASIK laser eye surgery.
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 eye 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 many clinics) the flap was made by a physical cut with a very 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. However 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 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.
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Comment by Dan on 12 December 2008:
If the healing is to do with the flap thickness, then surely sub 150micron flaps created by a blade would be expeted to heal in the same way?
Comment by Dave Allamby on 13 December 2008:
Hi Dan
Good question. It appears you want a flap of 110-120 microns or less to get the healing benefit. We know we can still lift flaps thicker than that, even years later.
Our Ziemer femtosecond laser cuts flaps around 102 microns with a very small deviation. Blade cutting microkeratomes aimed at 90 micron flaps have also come out this year to compete with the femto laser flap makers. But these flaps are getting pretty thin and the blade devices dont have as tight a standard deviation of thickness variability as the femtos, it appears. Remembering that the top 50 microns is just epithelium skin cells with no structure, it increases the risk of cutting a bad flap.
We have the option with the Ziemer to make 90 or 80 micron flaps but we dont, and thats with better accuracy than the blade version. Plus all blades have to flood the cut with water, which introduces a big variable into the laser effect. Provisional data suggests our enhancement rate has fallen from 3% with a blade to 0.5% with a femtosecond laser! Pretty impressive boost of safety for patients.
Thanks for the question
Regards
Dave
Comment by Dan on 9 April 2009:
If the flap heals down then would this not pose an issue if retreatment was required? Surely it would be risky to re-lift a flap which has healed and the alternative of performing lasek on top of the flap would also be risky presumably.
Comment by Dave Allamby on 15 April 2009:
Hi Dan
Good question. Retreatments are not common, e.g. 1-2% following myopic LASIK, so we are much better to have a well bonded flap that has healed down for the 98% of patients whom we will not see again. For those patients we will be treating again leaves us with two choices: LASEK over the flap (have done this numerous times without problems) or recut the flap with the femtosecond laser at the same or different depths.
Best regards
Dave
Comment by F Hussa on 30 April 2009:
Hi Mr Allamby,
Your question and answer session with Dan has been very interesting.
You state that ‘you want a flap of 110-120 microns or less to get the healing benefit.’ So that basically means that if a sub 100 micron flap is created using the blade device then it will heal in the same way as a laser created flap . This means the eye regains strength again with a blade flap aswell.
In conclusion can’t it be said that that if a sub 100 micron flap is created using the blade device the eye regains strength?
It can get confusing for patients about whether they should go for blade or bladeless technology. Please can you comment on this.
Surely patients should be given the full picture and not just told be certain clinics that the eye will not regain full strength if they go for the blade option. Surely the sub micron issue should be explained in full to allow the patient to make an informed choice that is value for money.
Regards
F.H
Comment by Dave Allamby on 3 May 2009:
Hi FH
Its an interesting question, which I think I should write a full blog post on to cover all the bases. Simple answer is that blade free outperforms blade cut in multiple ways, even when the blade cut is in the 100 microns range. I will post in the next few day on this topic and show that blade free is the best value for money, even though more expensive at most clinics. FYI our blade free prices at FOCUS are cheaper than blade-cut prices elsewhere – see my last posting on laser eye surgery prices at various London clinics.
Best regards
Dave
Comment by F Hussa on 5 May 2009:
Hello,
Thank you for your response.
However, it may be asked why do you reject the creation of flaps using a microkeratome blade as detailed on your blogs but then offer blade flap creation using a microkeratome to all your patients? Or is this not being offered anymore?
Clearly the best thing for surgeons to do would be to outline the possible pros and cons of both treatments and let the patient decide? Isn’t this more ethical and upfront/honest? Indeed some websites do just that.
I have found during my research on the Internet and questions to other clinic(s) several advantages of the blade technology approach some of which are that:
‘Flap creation with a precision microkeratome in experienced hands is quicker and less stressful on the eye than other methods.’
‘The flap can be separated very easily with the microkeratome, prior to the laser procedure because it is not left ’sticky’ from any lasering process and therefore less prone to becoming damaged or torn.’
‘The healing times for microkeratome flaps are the same as laser created flaps (even though this is sometimes put forward as a benefit of laser created flaps).’
‘The chances of post-op infection are the same for microkeratome created flaps as they are for laser created flaps.’
‘There are less reports of transient light sensitivity with microkeratome created flaps.’
Now the layman gets surgeons quoting different research and advantages and disadvantages to support a particular view. Isn’t it best to let the patient decide by giving him/her a balanced view of the pros and cons of each treatment?
I am not trying to be awkward but merely posing some sincere questions.
Thank you again.
Regards,
F.H
Comment by Andrew on 13 May 2009:
Dear all
I am going for a LASIK next week. In the clinic they have the possibility to cut flaps of 90 by blade. The offer as well the femto-laser cut.
I am doing skydiving quite often and need a fast healing of the flap.
What would you recommend. I am really getting very uncertain about what to choose.
Thanks for your help
Andrew
Comment by Dave Allamby on 14 May 2009:
Hi Andrew
Research on flap adherence from Professor Michael Knorz in Germany (in animal studies) shows that femtosecond flap adherence is 250%-350% stronger with laser flaps compared to blade flaps at 10 weeks post-op. So go for the femtosecond flap.
Regards
Dave