SAFETY NOTE: Does the LASIK flap ever heal?
Dave Allamby | Nov 07, 2008 | Comments 53
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.
Filed Under: LASIK • Safety • Technology
hi Stevie
People should not be guided by £395 headline prices. The reality is that quality laser eye surgery cost £3-4,000+, ...
Dear Dave,
Like most, I've been researching the possibility of surgery for some time, and have slowly noticed the high street ...
hi my husband went to have his eyes done today and the exact same thing happened!
i complained bitterly and pointed ...
Hi Dave,
My girlfriend has just been for a consultation today with a view to undergoing laser eye surgery. Unfortunately owing ...
Hi Terry, I have had a Lasik eye surgery to correct my vision about a year ago. I have been ...
Hi Dave,
I had Lasik treatment on both eyes three months ago. I now need a recorrection. My surgeon told me ...
I also have TLS and am just now (2 years after surgery) getting treated for it. It's common for it ...
I am in the Canadian army and can't decide on which procedure to go with because I am going to ...
Hi Dave
I've been reading all the posts and they sound very helpful. I've been very tempted to get lazer eye ...
I am 17 and would love to be a pilot in the RAF but am myopic. Do you know if ...
Thank you very much for your answer, it really calmed me down a bit.
Best regards,
Eleonora 
Hi Marie
The Clinical Suitability Guidelines followed when patients are assessed for Laser Eye Surgery at Optical Express are set and ...
Dear Dave
Thanks for the reply and the information you have put my mind at ease and my glasses dont have ...
Hi Dave, Thank you for the information; it has certainly given me food for thought and I'm so glad I ...
Dear Dave
That's really helpful - thank you. I plan to book an appointment at your clinic so that I ...
Dear Dave,
Thank you for your quick reply.
Also, many thanks for explaining this topic a bit more detailed. I am a bit more relieved about this now!
A last question;
I am planning to do the Lasik surgery and then go on a 2.5 weeks holiday 1 month after the surgery.
Is it risky to do so, if something happens?
Would it be better to postpone the surgery after the trip?
Thanks a lot for your time!
I really appreciate your imput!
Alice
Hi Alice you will be fine to go then. complications such as infection or inflammation occur in the first few 48 hours or so. You will be fine to travel one month later. Enjoy your trip! Dave
Hi Dave, Hope your good mate. I would like to ask you how does this exactly work. I have seen the video on You Tube. Where it says no blades etc. What I want to know is that, how is the flap cut ?.. or does the machine cut it etc. Hope that makes sense Dave let me know how it works in detail.
Cheers
Thanks Kaz. I will post a video and article this week showing how the femtosecond laser works. Best regards, Dave
Kaz, I have just posted a video on how Z-LASIK works, under the LASIK category on the home page. Regards, Dave
Dear Mr. Allamby
I am thinking of having lasik here in Tokyo.
On the website of one of the clinics it says that Intralase makes a 80 degree cut of the flap and the Femto LDV a 30degree cut
(see website picture below)
http://www.kobeclinic.com/ophthalmic-treatment/ilasik/ilasik_zlasik.html
They say that the 80 degree cut is better because it leaves the eye stronger after the surgery.
Is that true?
Does the angle of the cut influence the healing process and the strongness of the eye after the surgery?
I am a bit worried, that if I choose the Femto LDV the flap is easier to dislocate after the surgery…
I would really appreciate your objective professional opinion.
Thank you!
Best regards
Alice
Hi Alice
The side cut angle was introduced by Intralase and promoted possibly to differentiate following the introduction of the Ziemer Z-LASIK system, but I think this is a non-issue. The largest Japanese clinics however, Shinagawa LASIK, were using all Intralase systems, 8000 treatments per month, but have now switched over to Ziemer. You don’t need to worry about flap dislocation. Choose based on the surgeon first of all.
Best regards, Dave
Hi Dave,
thank you for your quick reply.
I was actually considering the Shinagawa clinic as well,
they use the FemtoLaser in combination with the Amaris.
Do you think this is a good combination?
I can’t really request a special surgeon (or, I can but have to pay for it…), but they say all surgeons who do the AmarisZLasik have done more than 30 000 surgeries. Is that a good indication?
So just to be clearify this;
if I do the surgery will the flap heal totally?
Would there be a possibility even after years, that the flap get’s dislocated, maybe by an airbag or so?
Thank you so much for your time,
this site is really great!!
Best regards from Tokyo!
Alice
hi Alice
Yes, the Amaris is an excellent laser, and is a nice combination with the Ziemer for Z-LASIK. Their surgeons have done a huge volume and ought to have seen almost every possible variation, which is what you want.
For flap healing ‘totally’, we don’t know the answer fully yet. We do see the thin femtosecond flaps being harder to dislodge and lift as time goes on, compared to thicker (e.g. blade) flaps, and I have experience femto-LASIK flaps that were impossible to lift, where I have never come across that will blade flaps and always been able to lift the latter. Is there a possibility to move from direct trauma, then perhaps so but very hard to quantify, except to say it would be rare.
Glad you love the site!
Dave
I don’t understand this statement since Intralase preceded the Z-Lasik
John
I mean to differentiate following the introduction of the Ziemer laser. They had previously held 99% market share and obviously did not want to give any ground to the newcomer, so began promoting side cut angle issues.
Regards
David
Dear Dave,
I still have a question concerning the side angle.
I have been reading a bit on the internet and I can find a few articles, which also say that the 50-90 degree cut leaves the eye stronger after the Lasik operation than a 30 degree cut.
You mentioned you think the side angle cut is a non-issue,
could you explain to me why you think that?
It sounds logical to me that a 90 degree cut is more likely to heal than a 30 degree cut…
I would really appreciate your honest opinion about this, I am quite unsure what to choose.
Thank you so much!
Best regards,
Alice
Hi Dave
Hopefully you can help, I had Lasik with Wavefront technology to correct a low short sighted prescription about 9 weeks ago from optical express and have struggled with light sensitivity (always need my sunglasses) and an overall strange feeling where my eyes make me overwhelmed, i can see everything but its almost too clear, i get slightly dizzy sometimes and quite anxious. Have you heard about these type of symptoms and is there anything you can suggest?
Thanks Debbie
Hi Debbie, If Optical Express performed Intralase LASIK (blade-free) then you likely have transient light sensitivity (TLS, inflammation within the cornea from the Intralase laser energy) and may need additional steroids to settle this more quickly. Go back to see you surgeon for a check up and advice.
Best regards, Dave
Thanks for your quick response after much worry I appreciate it. I will contact them tomorrow.
Debbie
Had Lasik done 5 weeks ago, after 3-4 weeks I got real sensitive to light and waited another week before I went to see the doctor.
He told me to use steroids for one week and it will go away.
It was great in the week I was taking the steroids, but after I stopped I noticed the sensitivity again and it get’s real bad. The Doctor told me not to take it longer then one week without a one week break.
How long does it take for TLS to go away.
Hi Tanya
We don’t see TLS (transient light sensitivity) with the Ziemer femtosecond that we use at Focus. I don’t have any personal experience of treating TLS as I don’t use the Intralase laser so I can’t really advise you here. Sorry!
Best regards, Dave
I also have TLS and am just now (2 years after surgery) getting treated for it. It’s common for it to take a stronger dose of steroids than you took. I think a common dose is of Flarex 4 times a day for a week, then 3 times a day for a week, two times a day for 2 weeks and then once a day for one more week. You can see this article for more info:
http://www.osnsupersite.com/view.aspx?rid=6299
I hope this helps!
-brook
Thanks Brook. For UK readers, Flarex is called FML here.
TLS stands for Transient Light Sensitivity, a term coined by the Intralase company. TLS is a problem peculiar to the Intralase femtosecond laser (sometimes called iLASIK on the AMO platform), and requires steroids by drops and/or orally to resolve, and said to occur in up to 1% of cases. Vision remains good and the cornea looks normal, but there can be severe light sensitivity.
I don’t see any TLS even after thousands of cases with the Ziemer femtosecond laser (Z-LASIK), and so can’t offer more advice on treatment.
Regards, Dave
Dear Dave
I had an Optical Express consultation yesterday to talk about laser surgery for my eyes. I’m 35 years old and short sighted, with a right eye prescription of -4.50, left eye -3.25 and minor astigmatism in both. Apparently I’m a good candidate for LASIK, but I have a couple of concerns. Wounds to my skin tend to heal fairly slowly and to leave a scar (even when the dermatologist has said they wouldn’t). Also, my skin seems to be sensitive. It’s prone to contact dermatitis from sticking plasters etc and my ears lobes gradually go red and swell slightly when I wear earrings.
Do you think any of this puts me at increased risk of complications from laser eye surgery? Eg, am I at greater risk for corneal scarring or of the flap not healing properly after treatment? Is there a particular procedure you would recommend for me? Optical Express recommended Wavefront Intralase LASIK.
Would it be best to have one eye done at a time? If so, how long should I wait between eyes?
My priorities are result and safety. I’m not so worried about comfort.
Many thanks for your help with these questions. This is a great website.
HM
Dear HM
Your contact dermatitis should not be a problem. As for skin healing, likely the same. There is a condition of abnormal dermal healing called keloid where wounds heal with excessive scar formation. In this case, one small study found no problems with LASIK for these patients but there is not a definitive answer. However most surgeons I speak to will perform LASIK but tend to avoid PRK. You do not have such a condition and so should likely have no healing issues, although that would be impossible to say with 100.00% accuracy.
It is quite reasonable to have one eye at a time, and wear a contact lens in the other eye in the meantime. You would have to leave the lens out for several days before each procedure. You only need to wait, say, 2 weeks between eyes and confirm the flap is appearing to heal normally.
Best regards, Dave
Dear Dave
That’s really helpful – thank you. I plan to book an appointment at your clinic so that I can get a second eye exam and opinion before deciding whether to go ahead – I am naturally cautious! – but it sounds like it will be fine.
HM
My pleasure!
Dear Dr Allamby,
I am thinking about having Laser eye surgery done and am researching as much as I can about the subject. This includes researching the details of all the equipment used in different clinics! I like to be thorough!
I wanted to ask about your Excimer laser, – the Wavelight Allegretto Wave Eye-Q. I understand this is a very good machine, – It has a 400Hz eye tracker, a very fast treatment rate, (which is highly beneficial in the accuracy and safety of the treatment). It also maintains a prolate cornea prfile which is beneficial as spherical abberation problems post surgery are much less likely to occur than it the case with other lasers that produce a more oblate cornea profile post surgery.
I notice too this machine is very flexible as it can be configured to perform Wavefront guided, Wavefront optimised or Topography guided ablations. I wanted to ask which of these treatments you generally use for most patients and if there is a choice at all? (can you pay more for the guided treatment if its suitable?). Or does the type of ablation used depend on the particular case and desired correction? I understand more tissue is removed in the wavefront guided treatment (as compared to wavefront optimised) but in general the statistics show that wavefront guided treatment has the best chance of minimising post surgery problems with increased higer order abberations and possibly even can reduce HOA in some cases compared to pre surgery.
My prescription is quite low myopia of -2.75 in each eye with minimal astigmatism ( I think that about -0.25 in each eye) , – can you give me a rough quote of the cost and which type of treatment is most likely to be used in general for a precription like this?
Many thanks,
Elizabeth
Hi Elizabeth
The type of treatment (wavefront optimised, guided, or topography guided) depend on the individual patient. Optimised corrections are by far the most common and correct the wavefront profile component that matters to getting excellent vision. A recent study showed no benefit to performing WF guided corrections on the VISX laser compared to WF optimised treatment on the Allegretto Eye-Q, including high order aberrations, suggesting correcting other aberrations beyond spherical aberration were not of benefit to the final outcome.
The cost for blade free wavefront Z-Lasik for your prescription would be around £1350 per eye.
Regards, Dave
Dear Dr Allamby,
I have recently been for consultations with Ultralase, Optimax and Optical Express with a view to getting Waverfront Lasik. The last prescription from my opticians (Jan 2009) measured my eyesight as:
Right – 3.50 with astigmatism -1.75
Left – 5.25 with astigmatism -1.75
However, the three consultations have left me confused as to what my current actual prescription is. They all measured this using the same machine (where you look at a little balloon) as well as optometrist tests. However, all three gave me different measurements for my prescription, with the results ranging from
Right – 3.50 to -4.25 with varying astigmatism
Left – 5.25 to -5.75 with varying astigmatism
Optimax also advised me that I had relatively thin corneas (although this wouldn’t prevent them from offering me treatment) whilst Ultralase said I had plenty of corneal tissue.
I wondered if you could advise why my prescription would be measured differently? As I presume these are the figures they use to programme the laser to shave the appropriate amount off my corneas, I want to make sure they have the correct measurement at the beginning! I thought by getting a second and third opinion it would confirm what adjustment was needed, but they have just all confused me more and I am now seeking further opinions
(including a consultation at Focus).
Many thanks,
Karen
Hi Karen
That does seem rather too wide a spread of results. One can expect some variation, certainly + or – 0.25D is very common between testers, but not 0.75D. Of course, yes, one has to have the right measurement to enter into the laser. Some doctors will recheck the refraction again on the day of surgery, but sometimes this optometrist measurement is the one that is used. Happy to see you at Focus and I will ask on of my team to email you, if you wish.
Best regards, David
David,
Many thanks for your quick reply. I am now booked in for a consultation at Focus (presumably with one of your colleagues) this Thursday, so hopefully this will shed some light on what has been going on/my actual measurement is.
Many thanks,
Karen
Karen, we will look forward to seeing you then and getting an accurate measurement.
Regards, David
Dear Dave i need help and advice what to do, june 2007 i had laser treatment with optimax in Brighton after wearing glasses for only three years mainly due to age as now 44yrs old and due to my work in casinos. within 6mths one eye had deterated, i had had lasik and waverfront as well as the basic 395 treatment. optimax offered re-lasering to the eye making one eye long sighted and the other eye short sighted. i said i didn,t no what was best to do but having spent 3340pounds and stil paying was upset why it had deterated so quickly in fact in 6mths. optimax left the dission 2 me when i went to consultants i got upset as there whole attitude was we only advice u on lasik and waverfront it was your choice. i was surprised at there attitude about it all and felt a little cond having spent so much and there lack of intrest. like the dentist i went on what they adviced knowing no better,but thought it would of lasted longer than 6mths.i was never rude at anytime but there lack of intrest putting the choice of what to do after in my hands nothing got done whilist my eye continues to deterate im paying a bill and a very upset customer i walked away crying as the surgen was rude and shrugged he,s shoulders meanwhile the problem unsolved now living in London i have been adviced to get a second opinion before to either go back as still paying for it or to decided what to do but soon as my eye deterating more and after spending so much did not want to end up with glasses again. can you help me or advice me a very upset unsatisfied dissapointed optimax customer please can u guide me. yours sincerely Lisa Brett
Dear Lisa. I am sorry to hear your experience. You should give Optimax the chance to correct your problem first, perhaps to see a different surgeon than you saw before. If you have not done so, first consider a letter to your Optimax clinic or the head office, outlining the story as you have done here and give them the opportunity to rectify matters. In addition, all clinics have to have a complaints policy and procedure in order to be registered with the Care Quality Commission, which outlines the steps to follow if you are not happy with your treatment or service. Each clinic can provide that upon request.
Best regards, Dave
Hi, I have -2.00 in each eye and wondered how much this would cost to be corrected? Also, what aftercare do you offer?? Thank you
Hi Rose, Focus offer a lifetime care guarantee so if you ever need an enhancement for your distance vision it will be free. The price for Z-LASIK which includes wavefront and blade-free femtosecond surgery will be around £1247 per eye, minus the current £300 special offer from the total, so £1097 per eye
Thanks
Dave.
Hello:
Just looking information about lasik on the web, I came across this blog and the last comment got my attention that you said that the cornea does not heal strongly when cut deeper. I am wondering how many microns is consider a deeper cut? And comparing microkeratome with femtosecond what is the average flap thickness for both?
Thank you
Best regards
Hello Thomas. Most modern thin flaps are created with a thickness of 90-110 microns using a femtosecond laser, and also possible with newer SBK keratomes. Blade cut flaps are usually in the range of 130-160 but occasionally can cut much thicker than that.
Regards, Dave
Hi Dave,
I recently got custom lasik done on April 29 2010 with a microkeratome. I’m worried now because im reading all this stuff on how the flap never really heals. How easy is it to dislodge the flap? And How worried should i be and can they amputate the flap if it ever becomes dislodged?
thanks Dave
Hi Jamin
Yes, it is true that the flap interface does not heal strongly when cut deeper, as with most (blade) microkeratomes. It is possible to lift those keratome flaps even years later. However, the flaps will not move with normal daily life activities, and are only at risk with direct significant trauma. There are case reports of flaps moving with direct injury, including an air bag, but these events are rare for most people so you don’t need to worry.
The better healing at the interface of thin flaps is one reason for the introduction of femtosecond lasers, which is now available at 80% of UK clinics.
Best regards
Dave
Many thanks Dave, would PRK therefore be a less damaging proceedure as it does not cut a flap or weaken the cornea?
Best regards,
Mahesh
Hi Mahesh
PRK will cut fewer collagen fibres, that is true, but this should not be clinically significant or safer than LASIK performed on suitable patients. Both treatments should be in line with safety limits, of course.
With best regards, Dave
Hi Dave
I am considering PRK or LASIK surgery and have read different opinions on the internet. I found the following negative comments about the surgery below and was wondering if you could comment on their validity.
1) the tensile strength of the LASIK flap is only 2.4% of normal cornea. LASIK flaps can be surgically lifted or accidentally dislodged for the remainder of a patient’s life.
2)LASIK permanently weakens the cornea. Collagen bands of the cornea provide its form and strength. LASIK severs these collagen bands and thins the cornea.
(3) The thinner, weaker post-LASIK cornea is more susceptible to forward bulging due to normal intraocular pressure, which may progress to a condition known as keratectasia and corneal failure, requiring corneal transplant.
3) LASIK affects the accuracy of intraocular pressure measurements,exposing patients to risk of vision loss from undiagnosed glaucoma.
4) Calculation of intraocular lens power for cataract surgery is inaccurate after LASIK. This may result in poor vision following cataract surgery and exposes patients to increased risk of repeat surgeries. Ironically, steroid drops routinely prescribed after LASIK may hasten the onset of cataracts.
5) history of diabetes in your family puts you at further risk in the years after surgery.
Hi Mahesh
Lots of ground to cover in your questions, so let me answer parts 1-3 now. This is all about corneal strength. The situation has changed with regards to flap with the arrival of thin femtosecond lasers (and also thin flap keratomes). Because of the irregularity in the anterior cornea, flaps will heal differently, and likely more strongly, than older deeper flaps. These thin flaps get hard to lift as time goes on, unlike thicker blade cut flaps which can be lifted years later. LASIK does weaken the cornea, but the question is if this is clinically significant? The incidence of keractasia in the laser population is approx the same as the incidence of keratoconus (KC, a disease where the cornea weakens and bends) in the general population, so are these ectasias actually KC instead? What is then very important is to go to the best clinic and doctor where thorough assessment is made of your corneas and scans of both surfaces to detect any signs of early or actual KC, and to ensure your treatment is in accordance with best practice.
With best regards
Dave
Great website, thank you! Thank you, Dave! Probably the best information resource I have seen so far!
Why do you need to create the flap in the first place? What does it do?
…and does blade-free mean blade-free all the way? Or do you still have to raise the flap by hand?
I have -3.5 on both eyes and -.75 & -1 correction (is this the right terminology?). What would the approximate cost of an operation with you guys be (complete, A-Z cost please)? Cost may be the deciding factor for me at the moment as I’m a student (though I am after the best here… – vision is way too important to cut corners with). I’ve seen the £300 off advert on the website… Do you offer Installments as a payment option?
Thanks Andrei
The flap creation allows us to access the collagen within the cornea, where we can make a permanent change. We still lift the flap manually with a smooth instrument. Careful flap handling and replacement is a learned skill and will affect the outcome.
The cost for Z-LASIK for your prescription is £1347 per eye, so £2694, less £300 for our current offer to £2394. You can spread that over 12 months interest free with a small deposit.
Hope that helps answer your questions Andrei. Let me know if I can be of further help in making your choice.
With thanks
Dave
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
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
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
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
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
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.
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
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
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?
Hi Alice, We cannot yet say whether the side cut is a significant factor. it is an interesting theory however and deserves additional research beyond the two Intralase papers. The authors are held in high esteem, very well respected and are quite open about their paid status as Intralase funded consultants.
The current papers look at early stage changes from different side angles. Yet these flaps will heal well and are hard to lift after a year or so, no matter what the side cut angle. What we don’t know is the structural integrity in the long term which is the key issue. if these thin flaps bond down well across the whole interface as we expect them to, then the side cut may not be relevant.
I await more research in this area as to its real significance. You do not need to base your decision on this alone I believe but more on the surgeon, lasers and clinic.
Regards, Dave