SAFETY NOTE: Does the LASIK flap ever heal?

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.

LASIK laser eye surgery flap healingMaking 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.

Filed Under: LASIKSafetyTechnology


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.

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  1. Dr S says:

    Hello Dave,
    I visited two specialists for opinion. First doctor uses microkeratome with customvue VISX. And so, I went for second opinion and this doctor suggested FemtoLasik after all preop work up with Pentacam and other tests. I am told I can opt for Lasik.

    I am 28 years old and my vision has not changed much i.e more than .25 since past 10 years. My corneal thickness is 560 and my vision in -7D Spherical in both eyes and cylindrical -2.5D 170 degrees in left eye and -2.25 D 10 degrees in right. She told me that flaps with femto heal really good in a week.
    But I am very scared that being a high myopic, I dont want to end up loosing my vision completely. Do these flaps really heal? What are alternatives to flap lasik? my doctor said Epilasik wont be good for me due to high myopia…
    I am also concerned if undergoing Lasik may impair my corneal health as I grow older. Does it have adverse effects when going through other eye surgeries say for cataract?
    And in worst case scenario, is going for corneal implants the only alternative left?

    What would you suggest for my kind of case??? what should I expect from getting FemtoLasik done and whats the worst that may happen? and do you really need to seperate the flap with that pointed instrument? What is the latest technology than Femtolasik with wavefront technology?

    • Dave Allamby says:

      hi Dr S. I wouldn’t choose any surgeon using a microkeratome. Out of date tech in 2013. Also I wouldn’t choose the VISX for such a high prescription. Femtolasik is the better choice and is what I would perform. Your corneas are thick enough for a full correction (at least with my WaveLight… you will have to check with your clinic and their laser as some take more tissue). I aim to leave 300 microns behind in the ‘bed’. Thin flaps do heal down and get hard to re list but takes a year or so. However, after a week if you rub your eyes the flap wont move so you can resume sports etc.
      Beyond that, sorry as too many questions and too broad for me to answer here! You will need to discuss these with your surgeon, as they ought to answer all those fully.
      Regards. David

  2. ????? says:

    Hi Dave,

    I have a problem maybe you can give some advice on.

    I want to know whether it would be feasible to convert an uncomplicated intralase (iFS) correction for hyperopia to PRK by amputating the flap then following the normal PRK post-op healing procedure w/ contact lens.

    I am involved in contact (fighting) sports and I was not informed about PRK before my lasik operation. Not really happy about that, and a bit freaked out about that I now have a flap on my eyeball that isn’t going to fully heal. Would be worried about this even without being involved in contact sports.

    From what I understand the conversion to PRK is the normal fallback for an aborted lasik or a traumatized flap. But I would rather have it done in a clean surgery than when I get poked in the eye or when an airbag goes off. Do you think there would be any optical changes after removing the flap? Would further laser ablation be required to negate these changes. The flap is reverse cut, would the edges require ablation?

    Leaving aside the issues of informed consent. I really just want to try to have this fixed so I don’t have to worry about my eye in the future.

    Can give you more specific details if that helps. Thanks in advance.

    • Dave Allamby says:

      hi, I would definitely advise against having the flap amputated from an uncomplicated LASIK. You would be at risk of creating optical aberration that may not be fully treatable, and so flap removal is only done when there isn’t really another option. LASIK flap trauma is actually rare, although obviously there are case reports of this happening, but the risk overall is very very low. Much lower risk than going for a flap amputation and its possible introduction of significant aberrations! Wear a head guard for the next 3 months, and leave your eyes alone.

      • ????? says:

        Thanks for your advice Dave. I was really worried about the flap healing when I posted that message. I have been told that the intralase flap should heal stronger than a microkeratome flap. Anyway, I m going to avoid contact sports for the next year to be safe.

  3. Olly says:

    Hi Dr. Allamby,
    I have just had intralase lasik with wavefront (4 days ago) and am slightly concerned that the day after the procedure I could see slightly better then I can now.
    Is this normal? hopefully I am just over worrying! In some ways I wish I had had lasek, as I am now worried about flap dislocation with my career in the building trade. I don’t think I could stomach another ‘touch up’ procedure wiith lasik as t would worry me disturbing the flap again, Is it possible to have lasek if it is necessary?

    Many thanks,

    • Dave Allamby says:

      hi Olly. Your eyes are still settling and much too soon to say how the final vision will be. If though it was good on day one, it will often end up very good. Flap dislocation is very rare and should not be worried about. Certainly a LASEK touch up is possible but you will most likely be fine.

  4. David says:

    Hello Dave, I have a question to ask.

    I had lasik on Feb 28th. Today its day 18.

    I had Lasik and the flap was created with the blade and my prescription was 3.50 astigmatism and 1.5 myopi on both eyes.

    I am having night vision issues, mostly regarding to starbursts and glares. Both occur even under daylight but are minor (sun reflecting on cars and glare when looking at windows/doors). When I watch TV and there are white subtitles on a back background they are ‘shadowed’. Is there any chance that this will diminish over time?

    Another question… since day 16 I have noticed that the starbursts/glare on my right eye are getting worse, I went to my doc and he said that my eyes were overreacting to the procedure and he could find minor scars that are probably causing these problems(the new and the old regarding night vision).
    He said that if the scar grows until the 30 day appointment we will need to discuss other options, but he didn’t sound happy about that. What can be done if it gets worse?

    Another question, when is it ‘safe’ to rub my eyes? On day 15 I woke up rubbing my eyes which got me really worried, but on the appointment with the doc he said everything but the scars were ok…

    Thanks a lot, your site is very helpful, I wish I could have read it before the surgery…

  5. Myopic says:

    I have -3.00 (both eyes) myopia with -1.00 astigmatism in left eye. Corneal thickness: 557(Right) & 560(Left). Is my cornea too thin for having traditional Lasik? No intralase option in my area. Will I suffer serious complication like corneal ectasia in future due to less corneal thickness after Lasik? Please Dr. I need honest answer. Its a matter of eyes. I am very tensed.

    • Dave Allamby says:

      hi Myopic. You have good corneal thickness at 557 and 560, slightly above average, so that is in your favour. However, the risk for a weakened cornea is more linked to the appearance on a combined set of corneal image scans, such as a Pentacam scanner provides. These scanners also provide statistical analysis of your risk for weakness, such as keratoconus. This is more important, to have a Pentacam or similar quality scan, rather than Intralase vs blade.
      Regards, David

  6. Lisa says:

    Hi Dr. Allamby,

    I just found this site and am so appreciative of you taking time to carefully answers all of our questions. I am planning to have LASIK surgery in the next week and some of the reports and site I have seen online have got me scared to let anyone touch my precious eyes. I read through all of your posts and great knowledge, yet I still have a stream of questions that I plan to cover with my eye clinic here in Tallahassee, Florida but I wanted to shoot several of these your way as well. Hope you will help, thanks so much in advance.

    1. does LASIK require lifelong post-op vigliance by patient and doctor?

    2. do steroids help or eliminate the common side effects of halos, dry eye, poor night vision, and light sensitivity?

    3. one advantage of wearing glasses is that I can always rub my eye when it itches, or when I awake…will I be able to still do that after LASIK?

    4. I read that the LASIK flap creates a permanent portal in the cornea for microorganisms to penetrate, causing lifelong increased risk of sight-threatening corneal infections…this scares me a lot!

    5. can steroid drops used after LASIK hasten the onset of cataracts?

    6. the FDA website says having LASIK on both eyes at the same time is riskier than having two separate surgies, do you agree?

    7. does my occupation as an accountant, staring at small numbers on a computer screen most 8 hours each day mean I may not be a good candidate for LASIK?

    8. what is a floater?

    9. should I take the day of and day after surgery off from my accounting job?

    10. is blood floating in the eye common after LASIK?

    11. what if I get sand in my eye (beach volleyball) or an eyelash in my eye after LASIK, can I touch my eyeball or flush my eye with water to get out the sand or eyelash? (that is what I currently do, performing the former usually).

    Thank you Doctor for indulging my questions.

  7. Marlene says:

    Dear Dr. Allamby, I am hoping you have some insight for a post-op symptom I have developed. 8 days ago I had intralase lasik on both eyes, with a correction on OD of -7.00D and -1.00D and OS -6.75D and -0.75D. I had a corneal thickness of about 600um and a flap of 110 was created. Maxidex steroid was used (one drop every 2 hours for first 24hours and then 4 times per day x5 days; Vigamox antibiotic 4 times per day x5 days, and Bion Tears continously). At 4 days post-op I began to experience a strange sensation with my right eye. I have a cold sensation on my eye, but more so on my eyelid and close to my brow, and in the inner corner near my nose. Its a constant feeling of cold or a cool draft in that area. I am wondering what may cause this sensation, what is it due to (maybe nerve damage, a problem with the tear ducts and glands, use of the steroid??) It seems to be less in the morning when I wake up but progresses throughout the day, being worst in afternoons and evenings. Sometimes it even alternates to a burning/stinging sensation. Is this a normal symptom? Will is pass with time? Is it permanent? I could use your expert knowledge with this matter. I have not even been able to fully enjoy my new vision due to this frustration..

    Looking forward to your reply,

  8. Lucy says:

    Hi there, first of all this is an excellent site!

    I am having LASIK this week (with one of the best surgeons in Toronto, Canada – with Intralase) and I am overly anxious about all possible complications. I am near-sighted with myopia of -8 in both eyes, and at first I was torn between PRK and Lasik only because of my fear of the flap (which thanks to your site I learned that it actually does heal! I was afraid that I would have the cut in the cornea for the rest of my life.) I am a candidate for Lasik because I have very thick corneas (over 600)… Which I learned is a good thing should I need an enhancement, although I am hoping I will not need one. What are the chances someone highly myopic like me will need an enhancement? I am concerned because I plan to move to another country in 5 months and will not be close to my surgeon any longer. When would i know if I need it?

    However, because I am highly myopic, I am still very paranoid for complications such as light sensitivity, night vision problems (halos, glare, double vision, starbursts – I have some starburts now PRE-surgery with my glasses!) Do these usually subside with time after Lasik?

    Then the scarier risks like Keratoconus, ectasia, and possible retinal detachment caused by the pressure device! Am I paranoid for nothing? Would my surgeon know if i am at risk for any of these after thorough examination and measuring?

    I have not slept since I read my consent form! Please help!


    • Dave Allamby says:

      hi Lucy, You are fortunate to have thick corneas, so that your -8.00 is treatable with LASIK. That is the way I would recommend to go. The chance of needing an enhancement does increase with prescription size, but is an easier proposition with LASIK compared to PRK. It also varies a lot between different clinics and surgeons, so best to ask your doctor what his rate is. My rate for myopia enhancement is only around 1 in 300 (0.3%), but some others might be 5% or higher. You have done the right thing by choosing the best surgeon you can. The decision is made around 3 months post-op, so you would have time to get that done before you move at 5 months.
      The incidence of night vision issues is linked to two main factors – do you have them pre-op (you do) and the size of the correction (you are in the high correction group). So you should expect that you will still have some starbursts etc after LASIK, as you do before. They will be more noticeable for the first few weeks, then will usually start to settle to similar to pre-op levels, but there is a small chance that it could be more than pre.
      For the ‘scarier’ risks you mention, through screening should help remove the chance for eg. keratoconus. You doctor can advise in your specific case based on the corneal scans. I would recommend a dilated eye exam 4 weeks post-LASIK to re-assess your retina. However, the clinical studies do not find a link between LASIK and increased chance of retinal detachment. But for high myopes, I personally like to dilate post op and confirm the retina (which is thinned in high myopia) is still OK.

      Best regards, David

      • Lucy says:

        Thanks David! I will contact my surgeon for further clarification about my particular case.

      • Lucy says:

        Dr. Allamby, it’s me Lucy again. I forgot to mention previously that I seem to have what I think might be floaters while looking at my white computer screen, and sometimes little stars for very short periods of time when I get up or sit quickly. I know this has something to do with retina. I recently had a dilated exam for pre-lasik, and my opthamologist didn’t say anything was wrong. What could this be, is it normal (maybe because I’m -8)? and do these pre-op symptoms pose any threats for Lasik surgery?

        Thanks for your knowledge and expertise!


  9. Varshan says:

    Dan, the healing has to do not only with the thickness but also with the fact that a keratome cuts like a splicer with graded edges and an FS laser cuts with rectangular edges, straight down.

    Hello Dr.Allamby!

    I’m an aspiring commercial pilot currently contemplating either an ASA or an FS lasik. After quite a lot of reading Azar’s, Vinciguerra’s, Pallikaris’ and Dr.Leo Bores’ books, I thought I’d come to the conclusion that I wanted to be flap-free but since then it seems like my flap dislocation worries have grown more than they ought to in my head, but saying I still do not want a flap and choose Epi-Lasik, what’s my risk of corneal scarring and/or grade 1+ haze(wearing sunglasses) considering I live close to the equator(Chennai, India.)? Also my surgeon isn’t keen on Vitamin C prophylaxis. My PPR was -5.10 OS and -4.5 OD with a -0.25 cylinder in both eyes.

    2. ASA and MM-C are fairly new when compared to PRK so do you think there’s going to be unforeseen changes in the future considering Sato’s patients only developed bullous keratopathy a decade after surgery!

    3. If I choose to have LASIK my preferred surgeon will use a Bausch & Lomb Technolas 217z laser with the Intralase system, and if I were to have ASA I would prefer to go to another surgeon, and he uses the Wavelight Allegretto Eye-Q. I’ve read the B&L is quite tissue-hungry and the eye tracker is impractically slow, but in your experience and word from colleagues do you suggest I steer particularly clear of the B&L laser for some reason? These are the only 2 Lasers available in my geographical vicinity and the guy who uses the Wavelight doesn’t have an FS laser.

    It’s also been a challenge for me to try and peer past all the marketing, honestly, nonsense that tries to create irrational exuberance for a certain procedure so I’m hoping you can give me an unbiased opinion.
    Thankyou so much in advance,

    • Dave Allamby says:

      hi Varshan, Of your options, I would certainly choose the WaveLight Eye-Q for surface laser, with mitomycin C. MMC is important considering the size of your prescription and latitude/UV exposure. There is very good follow up data looking at multiple aspects of corneal health post PRK, with and without MMC, which confirm no difference between the eyes up to 5 years post. This is very different to what Sato did in Japan in the 1950s, cutting into the posterior surface of the cornea, and you can’t fairly compare that with the worldwide research and application of the use of MMC. The Sato procedure would have led to rapid and major measurable changes in the posterior corneal health. You will be more likely to drop vision from haze than from the MMC.
      Regards, Dave

      • Varshan says:

        Thanks so much for your reply Doctor. Just to get your opinion on a few points you missed out:

        1. What’s your experience with corneal scarring and what’s my statistical risk of developing a) scarring and b) significant haze.

        2. Your take on how Vitamin C may impact re-epithelialization and fibroblast proliferation.

        3. My scotopic pupils were 6.7mm each and I’d like to again stress that significant haze or night-time complications are important to me as I’m only having this surgery so I can give myself the best chance possible of achieving the dream of being a pilot.

        And again considering all these things you suggest I avoid the Intralase/iFS + B&L and go for the Wavelight?

        Thanks so much again, this is a gem of a website.

        • Dave Allamby says:

          Hi Varshan, you are better to target the keratocytes and potential haze with MMC in your case, rather than vitamin C. MMC will slow the re-epitheliazation by about a day. Your pupils are of normal size. The relevance of pupil size to night vision symptoms is still being debated. E.g. the recent presentation this month by Schallhorn:

          “Large pupils not at greater risk”

          Patients with large low-light pupils are not at greater risk for quality of vision or quality of life symptoms at 1 month post-op laser vision correction, despite persistent rumors to the contrary, reported retired Navy Capt. Steve C. Schallhorn, M.D., former director of Cornea Service & Refractive Surgery, Naval Medical Center, San Diego; and professor of ophthalmology, University of California, San Francisco.
          Best regards

  10. Brian G says:

    Hi, I am in Canada and went in QC last October ( 21, 2011) to have Intralase. My vision was myopia with -6.25 with sligh ast. -.25 ( i did not know that before going there)…

    My question is: My vision regressed to +1.00, see blurry at far and can not really focus, I am going to see my optometrist for a follow up in February. Will i need enhancement or my vision *or cornea* will fix by themself?

    I had all laser surgery and hoping in all my life, that the flap will not fly in the air when riding in bike or going to take a plunge in the water.


    • Dave Allamby says:

      hi Brian, I am guessing you mean regressed to minus one? With blurry distance vision but good near vision? If it is -1.00 then it will not fix itself by now and an enhancement will be needed. Don’t worry about the flap moving in everyday life, it doesn’t happen.
      Thanks, Dave

      • brian says:

        Yes, this is what I meant, blurry at distance.
        don’t know why but i am scared like he** ;) may be because I know what I went trough the first time. having the thing in my eye to flatten it.
        But look forward in other part. I am definitely not going back to glasses for distant vision. ;) I will keep you posted (later in May-June 2012)

        Thanks for your reply.

        • Dave Allamby says:

          Brian, my pleasure. You won’t need to have the strong pressure feeling to flatten the eye next time, as your doctor can relift the existing flap, so you should find it easier if you need an enhancement.
          Regards, Dave

  11. Kieran says:

    Hi Dave
    I had lasik done four weeks ago and I was -8 in both eyes with some astigmatism. I can function without glasses now but ideally I would like the vision to be sharper and at my one month checkup I was told there was still a -50 left. Is my eye sight likely to improve further and if not what options di I have in the future.

    • Dave Allamby says:

      Hi Kieran, Its quite soon at 4 weeks following LASIK for such a high prescription and it may all settle over the next two months. Wait and see, and then discuss with your treating surgeon for more advice at the post-op 3 month mark. An enhancement procedure may be offered if the benefits outweigh the risks, assuming there is sufficient tissue remaining to carry out an extra ablation.

      Best regards

    • Dave Allamby says:

      Hi Kieran. Can take 3 months to fully settle so still time. Of course, -8.00 with astigmatism is a very large prescription, so -0.50 is not greatly off, esp if the other eye is even better. Wait until the 3 month point and discuss with your treating surgeon. You have to balance the risks of an enhancement (flap lift plus excimer) agains the benefit gained from a monocular -0.50 when binocular vision is (presumably) very good. Again, all to be discussed with your surgeon.
      Regards, Dave

  12. RJ says:

    Hi, i had Lasik 6 months ago and i now see perfect 20/20. However i have a slight straie in my right eye and there is an annoying pain in that eye. Would relifting the flap and having it cleaned and ironed out help reduce the pain. Or is it not worth the risk? My Surgeon claims the pain is dryness but it feels like their is debri under my cornea that needs to be cleaned out.

    • Dave Allamby says:

      hi RJ, Any pain is not linked to striae so no need to lift the flap. Much more likely linked to dryness as your surgeons says – follow the advice for treating that. Flaxseed oil supplements can help, taking 2-4g of oil as capsules with food for 6 months. Takes around 2 months to see the benefit. Regards, Dave

  13. theresa says:


    I had Blended vision laser on the 6th October 2011, my vision is not bad but l have a constant line of blurring ie: when iam reading the distance eye or visa versa. My vision in low light is not to good and night vision is poor also, halos starbursts aren’t improving. How long do you think i have to wait for clear vision.

    • Dave Allamby says:

      hi Theresa, Night symptoms after bended vision typically improve during the first 3-6 months. The blur you describe from the opposite eye at distance or near is settled for most patients at 3 months or so. All these symptoms do depend greatly on the focus and prescription that has been achieved with each eye. You will need around 3 months for the eyes to settle after LASIK (for any kind of LASIK) if you were initially short-sighted, and can be 6+ months if you were initially long-sighted. Your treating clinic can let you know more at your 3 month check up.
      Best regards, David

  14. Raj says:

    hi dave,

    i got my lasik done last week. i can see properly from my left eye however in my right eye i still have minor cylinderical number left. do i need to go for retreatment? is it safe?

    is there any way i can vision back without retreatment


  15. abhijeet says:

    i have done my lasik a month before my CCT is 415 in both it safe to avoid post lasik ectasia??

    • Dave Allamby says:

      hi Abhjeet. It will depend on your corneal flap thickness. Assuming you had a modern thin flap approach, which it my clinic is 110 microns, then the residual bed thickness would be 305 microns, which is a safe amount. You would want to check what flap thickness was performed. If it was with a femtosecond laser (Ziemer, Intralase etc) then the accuracy will be high. If it was with a blade then there is more variation of flap thickness. A high res HD OCT scan would confirm the flap thickness if you want to be certain.
      Best regards, David

  16. Mas Rashid says:


    I am looking to go for laser eye surgery. One thing I noticed is that, lasik is more “sold” to the customer than Lasek. From my little research, it seems, as long as you are happy with discomfort/healing process of 4-7 days, it is better than Lasik in every way, from results, form safety, to not having to worry about dislodged flap etc.

    So, can you enlighten me? It seems as if surgeons just don’t want to bother with patients who complain about pain/discomfort, so just throw them towards lasik, even though it seems lasek is superior, resultwise and safety wise?

    What exactly is the risk of dislodge etc, because there are stories that they can dislodge and so fourth – and it isn’t really strongly attached. Has this changed since dual laser or?

    • Dave Allamby says:

      hi Mas. Actually, there is no difference in safety or results between LASIK and PRK, so choose the procedure you prefer. Incidentally, when I get my own eyes lasered next year for presbyopia, I am going to have LASIK. Flap movement only occurs with hard, direct injury is extremely rare in reality.
      Best regards, David

  17. nick says:

    Hi Dave

    I am wondering what happens if at some time in the future the flap becomes dislodged and lost? How is this treated and what is the outlook for the patient?

    • Dave Allamby says:

      hi Nick
      As i mentioned before, flap movement only occurs with hard, direct injury is extremely rare in reality. If the flap were to be lost, then the surface epithelial layer will recover the corneal surface. Often a surface custom laser treatment can be needed to help restore visual quality. The modern femtosecond flaps are of even thickness all the way across, so if lost will not cause a major refractive change. This is unlike blade-cut flaps, which are thinner in the centre and create a long-sighted shift if lost.
      Best regards, David

  18. Yaritza says:

    To measure the cohesive tensile strength of human LASIK corneal wounds.

    So again, how does the cornea heal stronger?????

    • Dave Allamby says:

      Yaritza, you asked about wound healing, and the abstract submitted to make the point was already answered in my article – it heals stronger compared to the blade cuts. That was the point of the piece. I would write more, but I think a polite question, and reasonable courtesy is important if you want to engage in discussion here. Regards, David

  19. Nic says:

    Dear Mr Allamby,

    I have a few questions

    1) Is it true that although you will achieve 20/20 vision, the quality of vision will actually never be the same as when you wore glasses. And is this more so for patients with high astig ie 200+?

    2) Is it true also that you will experience fatigue eyes more frequently and will persist long after the surgery?

    3) There was an article mentioning ‘sudden presbyopia’ which hits lasik patients suddenly, when they hit 40 years old. This is due to removing the myopia and thus removing the ability to see near objects? I am not sure what it means.

    4) Why do you not recommend epilasik since it does not even require a flap to be created. In fact is epic-lasik the best lasik?

    5) the wavelight allegretto machine is not Intralase, and therefore will not create any TSL problems?

    • Dave Allamby says:

      hi Nic. Thank you for your email. To answer your questions in order:
      1) Is it true that although you will achieve 20/20 vision, the quality of vision will actually never be the same as when you wore glasses. And is this more so for patients with high astig ie 200+?
      This may have been true years ago with older lasers but not today. The typical comment now is that the post-LASIK vision is better than they had with glasses or contacts. Genuinely, I don’t recall a patient over the last few years who had their myopia treated and said it was not at least as good as with lenses.

      2) Is it true also that you will experience fatigue eyes more frequently and will persist long after the surgery?
      Again, this is a no. You will have dryness for a few months post laser eye surgery which may give eye fatigue, esp after prolonged PC work. This does resolve though, and is helped with lubricant drops and sometimes punctal tear plugs, esp in the over 40s.

      3) There was an article mentioning ’sudden presbyopia’ which hits lasik patients suddenly, when they hit 40 years old. This is due to removing the myopia and thus removing the ability to see near objects? I am not sure what it means.
      Myopic patients have poor distance vision, and excellent near vision. If you correct the myopia, then they will have the same close vision as everyone else. And if they are aged 45+ they will be suffering from presbyopia, loss of close vision, which happens to every human, without exception. So patients who are presbyopic in middle age need to understand the loss of near clarity, unless they have treatment to correct both, eg. KAMRA inlay, Blended Vision etc.

      4) Why do you not recommend epilasik since it does not even require a flap to be created. In fact is epic-lasik the best lasik?
      Epilasik is not actually LASIK at all, but a form of PRK. Just a marketing angle to make it sound like LASIK. As long as patients are screened well, I prefer LASIK as the best option, and is what I would choose for myself. Safety is the same, as long as you are in the hands of a quality surgeon and centre. So don’t buy on price, please!

      5) the wavelight allegretto machine is not Intralase, and therefore will not create any TSL problems?
      The WaveLight Allegretto is an excimer laser for reshaping the cornea. The Intralase is a femtosecond laser for e.g. creating a corneal flap. Different kinds of laser

  20. Luthfur says:

    Hi Dave,
    Im thinking of having the Lasek surgery. I dont want the lasik as i dont want a weak point as they dnt fully heal permanently. I have type 2 diabetes. My question are:

    1) should i avoid it due to my diabetes?
    2) does the layer that is cut in the eye fully recover permanently? Either with the flap in lasik or the top layer in lasek?
    3) due to my illness should be worried of complecation later in my life?


  21. Mark says:

    Hi Dave,

    I’m 24yrs old and I from the US. I had my laser eye surgery done a few days ago using a femtosecond laser. My prescription was around -4D with astigmatism. My surgeon used some suction thing to make the flap.

    I was talking to a doctor friend who said that you can get a posterior vitreous detachment after surgery from the suction and also keratoconus.

    I’m really worried about this. How likely is it that I could get a PVD or keratoconus?

    Thank you


    • Dave Allamby says:

      Hi Mark
      First, the keratoconus. There is no confirmed increased incidence of this after LASIK (when it is called ectasia). The incidence of ectasia is the same in those who have LASIK and those who dont (keratoconus), at around 1 per 2000. So reasonable safe to not worry about that.
      For the vitreous detachment, two factors have been found to be important in determining the onset of PVD in a healthy subject: age and refractive error. By age 70, it is estimated that 2 out 3 people have partial of complete PVD, although studies vary widely. Posterior vitreous detachment does not directly threaten vision, but can be associated with floaters and flashing lights, and more rarely with retinal problems, including detachment.
      PVD does occur after LASIK in a percentage of low myopes ( est. 2-8%), increasingly so with higher myopes (20-25%), as shown by ultrasound studies. If you develop floaters or flashes in the first weeks after LASIK, ask your treating clinic to check your retina. But with a -4.00D prescription, you have about a 1 in 20 chance of PVD, which itself is unlikely to cause you any problems. Floaters are the most common symptom, and these do tend to improve with time in most, but not all, cases.
      Regards, Dave

  22. Sharif says:

    Hi Dave, I’m not sure if this will come too late since the last replies were from 2010. I had Advanced Custom Wavefront Lasik performed over 1.5 years ago, and I believe it was with a keratome. I am not sure if the keratome that was used is the one that you refer to as the competitor of the femtosecond laser that is used these days. If so, would this result in a stronger flap? My concern is, for someone considering a career in the police, is it possible for the flap to dislodge as a result of the dangerous nature of the job? I would appreciate any feedback you can provide me with.

    • Dave Allamby says:

      hi Sharif. I would not worry at all about injury to the flap for the career in the police you are considering as, while there are some individual case reports, these are very rare events. Join the police and do not concern yourself with your prior LASIK.
      Regards, Dave

      • Sharif says:

        Thanks Dave, I appreciate the response. I’m not too worried about it, but I always like to prepare for the worst.
        As for the microkeratome, if you had to guess would you say it is similar to the femtosecond lasers in that it produced a thinner cut?

        • Dave Allamby says:

          Keratomes usually produce thicker cuts than femtosecond lasers, which are typically used to create thin flaps. However, all depends on which keratome was used, as there are some now that produce thinner flaps.
          Regards, Dave

          • Sharif says:

            Thank you Dave – much appreciated.

          • Sharif says:

            Hi Dave, sorry I have another question. Does something like heavy weightlifting cause any sort of significant rise in the intraocular pressure that could affect the corneal flap?


          • Dave Allamby says:

            hi, you are quite safe with weightlifting. In fact, you are safe with all activities (except poking yourself in the eye just after surgery!). I have never seen a flap move except on the day of surgery itself, and even that is a rare event, happening only 1 per 3000 treatments approx in my experience. Also, easily fixable by smoothing out the flap again, so I have never had a visual problem from rare flap movement.
            Best, Dave

  23. love says:

    hi dave

    i am a newbie at this, could you give me the pointers i should be asking for and looking for when i choose a surgeon and clinic to get lasik, also which procedure is the best?


    • Dave Allamby says:

      Hi Love, For a surgeon, look for someone who has done 5000 or more procedures, and whom you can meet prior to surgery if you wish. In my opinion, you want to get femtosecond LASIK (e.g. Ziemer, Intralase), so a laser to create the flap and not a blade, and wavefront based treatment with my preference being the WaveLight or Schwind lasers. If you are myopic up to -6D, the VISX laser performs very well, according to their FDA data.
      You definitely want to see the vision results statistics from the clinic you have in mind, for your particular prescription. With the Ziemer and WaveLight combination, we now achieve 100% of patients with myopia up to -9D seeing 20/20 or better (95%)) post-operatively.

  24. Julie says:

    Dear Dave,

    I am about to get an enhancement surgery since my eye changed to -1.0 after just 10 months. I got the flap cut with the laser. I see that this type of cut heels quickly and I know doctor will not be using the cutting laser again, so how is he going to lift the flap? I’m terrified and thinking that I will be better off wearing glasses again. What do you think? Thank you

    • Dave Allamby says:

      Hi Julie
      We lift flaps manually, using a flap lifting instrument, which is usually a fairly simple process. It should be possible to lift a femtosecond flap at 10 months, but you wont know until it is tried. I had one patient that proved impossible to lift after 6 months, but that was unusual. You could opt for PRK enhancement with mitomycin, but I would opt normally to lift the flap first. You can discuss this with your surgeon before going ahead.
      We are now hitting 100% at 20/20 or better at Focus, so enhancements are getting increasingly rare. If they do happen, it is usually for patients with very high myopia.
      Best regards, Dave

    • Isabel Copping says:

      Dear Julie

      I am interested to know how you got on. Did you go ahead with the surgery, and are you glad you did so? I would be very grateful for your reply as I am in the same quandary as you were when you posed the question. I am not so much worried about the surgery itself but I am terrified that I could end up with more of a problem that I started with – ie. I could easily manage the way I am with occasionally wearing glasses rather than having the enhancement, but a good result if I go ahead could be amazing.

      I would really appreciate hearing about your experience of enhancement surgery.

  25. Alice says:

    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!


    • Dave Allamby says:

      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

  26. Kaz Singh says:

    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.


  27. Alice says:

    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)

    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


    • Dave Allamby says:

      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

      • Alice says:

        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!


        • Dave Allamby says:

          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!

      • John says:

        I don’t understand this statement since Intralase preceded the Z-Lasik

        • Dave Allamby says:

          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.

          • Alice says:

            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,

          • Dave Allamby says:

            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

  28. Debbie says:

    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

    • Dave Allamby says:

      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

  29. Tanya says:

    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.

    • Dave Allamby says:

      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

    • Brook Vanderford says:

      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:

      I hope this helps!


      • Dave Allamby says:

        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

  30. HM says:

    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.


    • Dave Allamby says:

      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

  31. Elizabeth Mitchell says:

    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,

    • Dave Allamby says:

      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

  32. Karen says:

    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,

    • Dave Allamby says:

      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

      • Karen says:


        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,

  33. lisa brett says:

    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

    • Dave Allamby says:

      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

  34. Rose says:

    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

    • Dave Allamby says:

      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

  35. 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

    • Dave Allamby says:

      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

  36. JAMIN says:

    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

    • Dave Allamby says:

      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

  37. mahesh says:

    Many thanks Dave, would PRK therefore be a less damaging proceedure as it does not cut a flap or weaken the cornea?
    Best regards,


    • Dave Allamby says:

      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

  38. mahesh says:

    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.

    • Dave Allamby says:

      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

  39. Andrei says:

    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?

    • Dave Allamby says:

      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

  40. Andrew says:

    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


    • Dave Allamby says:

      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.

  41. F Hussa says:


    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.


  42. F Hussa says:

    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.


    • Dave Allamby says:

      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

  43. Dan says:

    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.

    • Dave Allamby says:

      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

  44. Dave Allamby says:

    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

  45. Dan says:

    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?

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