High Myopia (Short-sight) and Laser Eye Surgery

Zoe asked:

I am interested in laser eye surgery, but am very short sighted(-10) would it still be possible?

Zoe, yes it certainly may be possible. It will depend mainly on your corneal thickness and pupil size in the dark. The best way to know is to have a consultation and have the measurements taken. Not all patients are suitable at this level of prescription though. If LASIK is not possible, PRK with mitomycin may still be.
The WaveLight laser that I use takes relatively little tissue per dioptre, so I find we often have a good chance to treat higher myopia. If there is not quite enough tissue in the cornea, and you are 40+, a good option can be to leave you between -1D and -2D, so at least you will be able to read without any glasses.

Filed Under: LASIKPRKQuestions


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. Chris says:

    I wonder how much tissue per dioptre does the wavelight laser remove? I came for a consultation at FocusVison and was told I was not suitable by the optometrist as you need to leave 350 micrometers of residue corneal depth. My prescription is -7.00 bilaterally with -2.75 astigmatism. Corneal thickness being 466 OS and 474 OD (with OCT. Although the evidence for 250-300 micrometers is somewhat patchy and poorly defined, of course I understand that ‘more tissue’ may be better.

    What is the figure you use for minimal residue tissue?

    I understand that the exact ablation depth is related to the optical zone and we want to minimize night vision halos and glare. Having said that, the optical zone on toric contact lens cannot be in excess of 6 mm so potentially what is the probability of LASEK/PRK leaving worse night vision than with contact lens?

    • Dave Allamby says:

      Hi Chris. thanks for posting. Actually Focus is my clinic. You of course have an extremely high prescription, being -7 in one axis and -9.75 in the other. The ablation is calculated on the maximum power, in your case -9.75. To do such a high prescription is possible but you need a thicker than average cornea to have enough tissue. In your case you have unfortunately very thin corneas. just not a good match for laser eye surgery I am afraid. We use 300 microns residual for LASIK (and 350 for PRK). Even with a small zone your calculation comes out at just under 240 residual for LASIK with 13 microns per dioptre, so a no go. (The WaveLight removes the least tissue of all the excimer lasers I know). Sorry we couldn’t help you here.
      Best regards, David

  2. Mary says:

    I am 44, have high myopia, -7D and -8D, have been wearing contact lenses and glasses . But my eyes started getting dry , can not wear contact lenses for whole day. I have consulted LASIK surgeons, one said I am candidate for LASIK with mono-vision surgery, the other doctor said I am not LASIK candidate, but PRK candidate. The cornea thickness is 525. Please advise your opinion, will i need enhancement later? thank you.

    • Dave Allamby says:

      hi Mary
      First of all you need to be certain that your eyes are not too dry, from your description of decreasing tolerance for contact lenses. It seems both surgeons you have visited have approved you, but do ask them to clarify how they are assessing your dryness and how they are confident that your eyes have enough lubrication.
      Regarding the procedure, with the WaveLight Allegretto laser that takes away perhaps the least tissue of all lasers, you should have enough tissue for a Z-LASIK correction, using a femtosecond laser to create an accurate and thin flap, and keeping the bed thickness above 300 microns. So my choice would be LASIK if I was doing it at Focus Clinic, all other things being equal and suitable. I too would opt for monovision as long as your brain can accept this – your doctor will need to do some tests to confirm your suitability for monovision. This should typically (in my experience) keep you out of glasses for almost all tasks until around 60 years of age. After that you may need some weak reading glasses to boost smaller print.
      You have a very high degree of myopia, and so may need an enhancement during the first year to ensure each eye is on target – this is very important when opting for monovision. Having LASIK makes this much easier, with a rapid and easy recovery, compared to another week of pain and blurred vision when repeating PRK.
      Best regards

  3. Pete says:

    Hi Dave,

    I am 45 years old (nearly 46!), and wear contacts lenses, my glasses prescription is Left -11.25 and Right -10.25 (contact lens prescription Left -9.50 and Right-9.00).

    I am also getting to the age where I need reading glasses – although strangely I can read pretty well in the daytime with lenses, but by the evening can’t read a newspaper with contact lens – but can read it if I wear my thick glasses instead of my contact lenses. My left eye is my dominant eye. Strangely for reading I can see more clearly with my left dominant eye. Also if I try my wife’s +1 reading glasses I can see good for reading with left but not brilliant with right.

    I recently went for a Laser surgery consultation (Centre for Sight), and was told my retina was normal thickness and adequate for laser. So laser surgery was an option but not particularly recommended due to:- high prescription meaning the optics of my eye would be altered making a RLE later in life more difficult to obtain good vision results if it was following a previous laser surgery. Also I do have medium dry eye – which I have been trying to aid with Omega Eye PRN supplements, and twice weekly hot compression for 5 mins at a time. I was told ICL was an option, with or without monovision.

    Before my consultation I was thinking that RLE would be great for me with a multi-focus lens, but was told I was a little young, and though my left eye has already has some PVD, it would be safer to wait until I was 50-55 in age when PVD had occurred – otherwise the risk of retinal detachment would be quite high.

    So I was told ICL is an immediate option, and then at around age 55 to consider RLE, or alternatively wear contacts and consider RLE when 55yrs.

    I was ideally looking for a solution that would not only fix my distance vision, but also my reading. I understand that with ICL there is no multi-focal option yet ? only monovision.

    Are there options that Focus Clinics would have that might be more suitable for me ?

    - I have read about KAMRA but guess my prescription is too high? I am puzzled why KAMRA is not offered over -6 (according to their website) as if I do a pinhole test I do see an improvement.

    - What about Laser Blended vision that Focus offer, how would that suit my case ? what would be the likely result, risks, long term impact, and how long would this last.

    - Ideally I’d like Laser Surgery with KAMRA, but I guess that’s not an option ?

    - Is Z-Lasik any different and less risky for me.

    Are there any new treatments on the horizon, that I should hold out for, as I am aware that my reading vision will continue to deteriorate over the next few years.

    Thanks for any advice you can offer.


    • Dave Allamby says:

      Hi Pete, that’s a good summary, and CFS are correct that your best option right now could be ICL. KAMRA wouldn’t be suitable with such a high prescription, as we don’t have any safety data at that level. Blended vision may be an option – you would need pretty thick corneas – but the dry eye you have adds a risk of permanent dryness, and BV works well when both eyes are accurately on target, one far and the other near, which is pretty hard to achieve with such high levels of myopia, without repeat surgeries, and hence more dry eye. I don’t think we have anything additional to offer at Focus, and ICL now or wait for RLE is correct (although retinal detachment is a concern). Thanks David

  4. Dileep says:


    My son has high myopia which has been increasing slowly. He is 8 years now and has -16 and -15 in each eye. What are the options for limiting the increase in his myopia year on year and what options do we have to correct the power with surgery such as Lasik at a later stage ?

    • Dave Allamby says:

      Dileep, Sorry to hear of the extreme myopia your son suffers from, which will indeed progress as he grows up. Once he has stabilised, which may be in his 20s, his treatment option would be an ICL, a lens inserted inside the eye, such as the STAAR Visian ICL. However, the maximum power available is currently -23 dioptres. If he was worse than that, some additional LASIK may be possible. Of course, by the time your son is ready for treatment, the lens options will be different and more choices will likely be available.
      Two factors have been associated with limiting progression of myopia: amount of near work, and UV light exposure. For near work, the more time spent focusing up close, the greater the tendency to worsen short-sight. For UV we have seen data where outdoor activity e.g. sports, with exposure to UV light (in moderation) has helped limit worsening of myopia, but I don’t believe we have data for this effect in extreme myopia, as the study was for more typical short-sighted prescriptions. It may help, but I honestly don’t know. So in summary, moderating time spent reading up close, and balancing with getting outdoors more may all help.
      Best regards, David

  5. johnny says:

    Hi Dave,

    I read about ICL and there have been studies that say that it is a better treatment then lasik. One of the studies is published in quite a number of medical journals.

    I would like to ask your opinion on this. Is it true that it avoids the problems of Lasik(dry eyes, night visions) and on top of it provides clearer sharper vision?

    When they say it is a riskier operation, how much more risk is it? Are there any numbers or percentages?

    • Dave Allamby says:

      Hi Johnny, depends on what prescription you are talking about. Some eyes are not suitable for LASIK, and so warrant ICL. For LASIK suitable eyes with typical myopia, LASIK is certainly safer and more accurate and with excellent vision outcomes. So that’s an easy choice.
      ICL is best used for extreme prescriptions in younger patients. ICLs also cause cataract in just over 5% of cases, often requiring a second intraocular procedure to remove the lens, and the ICL and replace with another implant. Hard to give a number, but overall risks for intraocular operations are higher, and the complications that can arise are significantly more serious than those we might see with LASIK.
      Best wishes, David

  6. johnny says:

    Hi Dave,

    Can we say that surface techniques PRK, LASEK and Epi-lasik will result in better results than Lasik in terms of vision? Which is the best of the surface techniques?

    Also what do you think of these platforms

    Allegretto Wave® Eye-Q Blue Line excimer laser

    Visumax vs Intralase Femtosecond Laser

    • johnny says:

      thanks in advance!

      • johnny says:

        hi sorry dave,

        allow me to clarify my second question.

        allegretto wave eye q blue line,
        visx star s4 ir,
        amaris 750s,

        which one should i go for? and why?

    • Dave Allamby says:

      hi Johnny, the outcomes between LASIK and the various surface laser procedures (PRK, LASEK, Epi-LASIK) are the same. The main differences: that LASIK settles in 4 hours versus 4-7 days, and that LASIK is much easier to enhance. For the surface laser options, again it’s easy = they are all same in terms of outcome and pretty much every other metric. You will come across various claims for one versus the other but you can ignore.
      Regards, David

  7. Melissa C says:

    I have a current prescription of -14 and -17 and am 43 years old in otherwise great health. Are there any options for me for this type of correction? Or does the high myopia itself rule me out? (given the other factors are within range) thanks

    • Dave Allamby says:

      Hi Melissa, Your option really is RLE( refractive lens exchange), effectively a cataract operation where your natural lens is removed and an artificial lens inserted to correct your extreme myopia. The main risks are complications at the time of surgery, and the risk of retinal detachment (RD) afterwards, with studies putting this happening in the 2-5% range, depending on age. The younger you are, the higher the risk. So those like yourself under age 50 can expect a ball park rate of around 1 in 20 (5%) by 5 years after. RD can be vision threatening and requires prompt surgery in a hospital to replace the retina.
      Best regards, Dave

  8. Sheila says:

    Hi , I had custom wavefront laser surgery 2 weeks ago. Now I have 20/40 in one eye and 20/20 in the other. I’m worried that my vision will always be blurry. Is this normal?

  9. Damian says:

    Hi Dave,
    I read an article today about SMILE, a new type of eye surgery for myopia and specifically high myopia. I wonder if you might give your thoughts on it. They speak about it as having advantages over LASIK as the cornea is less disturbed although I’m not altogether clear if that is an advantage not already present in the older version of LASIK, PRK. Do you see a future for it and do you envision yourself performing it at any point? Here is the article: www.thesun.co.uk/sol/homepage/news/4382792/Amazing-eye-surgery-caught-on-camera.html

    • Dave Allamby says:

      Dear Damian,

      Zeiss have put a lot of effort into this SMILE laser eye procedure to get their femtosecond laser to perform an alternative approach to correcting short-sight.

      It is interesting but however I see that this will not gain widespread use or replace femto-LASIK. It has a minority application only for very high prescriptions. It is inherently less accurate than modern femtosecond LASIK, as the excimer laser currently used has greater precision in reshaping the cornea to correct vision. The femtosecond laser used in SMILE can only be accurate to within several microns, whereas the excimer laser is accurate to a fraction of a micron. If you have an extreme prescription, say over -10, where you aren not suitable for Z-LASIK, then SMILE can be an option. There are others, such as an implanted lens for such extreme cases. For me, the Ziemer femtosecond that we use in Z-LASIK is a superior machine compared to other femto lasers.

      SMILE eye surgery isn’t something that we would offer, as we already have superior procedures for short-sight, and for us this would be a retrograde step.

      Best regards, Dave

  10. Amy says:

    Hi Dave,

    I am 25 and have a prescription of -10 in both eyes. In 2008 I noticed floaters in my vision and was told by the doctor that I have posterior vitreous detachment. Now after four years in 2012, the floaters are still the same shape and size.
    I would like to know if I am a good candidate for laser eye surgery and if laser would be a safe option for me?



    • Dave Allamby says:

      Hi Amy, Vitreous detachment and floaters are much more common in very high myopes like yourself. There is also an increased risk of retinal detachment compared to an average eye with or without laser eye surgery. However, the good news is that studies showed no increased risk of retinal detachment after LASIK in short-sighted patients, so from that aspect safety is the same as for other eyes. You may experience a change or even an increase in your floaters after LASIK though, which occurs in a minority of cases for patients with high degrees of short-sight.
      To be a candidate with a -10D prescription, you will need corneas with sufficient thickness, as well as the usual suitability criteria. I did a patient just last week with -10.50D, who was over the moon with his vision the next day. For such high prescriptions, it really is a life changing procedure that is hard for those of us with fairly regular eyes to fully comprehend.
      Best regards, David

  11. nrg says:

    Dear Doctor
    i have seen one websites claiming that those who are carriers of herpes keratitis
    should not have lasik.

    Is carrying herpes virus a strong contraindication for laser myopia correction surgery ?

    Thank you !

    • Dave Allamby says:

      Dear nrg, Yes you are quite correct. Having a history of herpes keratitis is a contraindication for laser eye surgery. One can try to pretreat with antiviral agents, but may not prevent re-activation of the virus.
      Regards, David

  12. nrg says:

    Dear doctor
    how long will it take to fix a myopia of -9.5 using the latest lasers (either schwind or wavelight)
    thank you very much !

  13. Ini says:

    Hello Dave,

    I’m 38 and looking at having LASIK. My vision is -6.50 in the right and -6.00 in the left.

    What kind of surgery will you advise? I hear there’s a new one called C-Ten. Pls help

    • Dave Allamby says:

      hi Ini, My choice for your prescription is blade free femtosecond LASIK, including any wavefront/aspheric option. C-Ten is a variant of PRK and offers no benefit apart from possible slightly faster epithelial healing, nothing actually new. There is a comment below in this list from a patient that had C-Ten.
      Regards, Dave

  14. Natasha Vidas says:

    Dear Dr Allamby

    I hope this is the right space to ask a question.

    I came in to FOCUS on Monday (28th Nov) for my laser eye surgery assessment (the staff were lovely and really helpful). After all the tests I was told that I have 20/12 vision with my contact lens correction, which is something I suspected but wasn’t sure about. The optometrist explained that not all people can see 20/12 no matter how much one tries to correct their vision with lenses – which is something I didn’t know. She said I was quite unusual in that I have a -5 prescription with 20/12 vision (with lens correction). I was told that the statistics for FOCUS and people obtaining 20/12 after surgery was 49%. I am keen to have the surgery done (and have provisionally booked to have it done next Tuesday 6th Dec at 3pm) but I am nervous as I might only end up with 20/20 or 20/15 post-op which is not as good as the vision I currently have with my contact lenses.

    I would really value your feedback/opinion on this. I guess I am after a little reassurance, not sure that is possible. One of the main reasons I chose to come to FOCUS was the excellent results reported for 20/20 vision post-op i.e. 100%, I didn’t realise that that might not translate into my vision being as good post-op as pre-op i.e. 20/12.

    My other question is, will my corneas be as strong post-op as they are pre-op or does one end up with weakened corneas and if so, what are the implications?

    Thank you so much.

    Kind regards

    • Dave Allamby says:

      hi Natasha. Good question, glad you asked that. It’s a common misconception that 20/20 is ‘perfect’ vision whereas it is rather a good ‘normal’ level of sight. We have two levels of vision in standard testing that are better than 20/20, namely 20/16 and 20/12. The maximum that a human eye is capable of is 20/10, beyond which there are not enough photoreceptors in the retina, i.e. not enough ‘pixels’. Very few people can see 20/10, but a percentage can manage 20/12 when both eyes are fully corrected with the best lens possible.
      Our patients who have LASIK typically report that they see better than they did with glasses or contact lenses, which is a testament to what modern LASIK is capable of. However, in your case at 20/12, close to the limit of human vision, there is no headroom left to improve on! Most of our patients are within 0.25 dioptres of the target refraction, i.e. from +0.25 to -0.25 when we aim for zero. You wouldn’t really notice +0.25, but at -0.25 you would drop one line on the chart, i.e. 20/16, without any glasses. Of course, if you choose to wear glasses of -0.25D you would see 20/12, but no-one would choose to do that! Why wear glasses when you can see better than 20/20?
      if you definitely want near the limit of human vision and a guarantee of that, then LASIK is definitely NOT for you! It comes down to your expectations. We can get in the upper 90s percentage of patients to see 20/16 without glasses, and half to see 20/12 including patients who could not achieve 20/12 previously with glasses or contacts. It’s a personal choice, in the end. But we don’t have now or in the foreseeable future, a technology to give 20/12 vision to most or all patients. Too many variables in a biological treatment, with all the variables that humans bring, such as healing responses, immune systems etc.
      Best regards, Dave

  15. Vicki says:

    Hi dave,

    I’m considering getting laser eye surgery. I have had two consults and was told I am a candidate for wavefront lasik but am on the border for cornea thickness in my left eye. My prescription is -7 in the right and -7.25 in the left. I also have astigmatism (-1.25 and -2.00). I’ve been monitored for lupus my whole life but not diagnosed and am worried that the combination of autoimmune, high prescription and thin cornea makes me higher risk for complications/needing enhancements. What are your thoughts?


    • Dave Allamby says:

      hi Vicki, Do you know your corneal thickness? Why are you being monitored for lupus? You have some symptoms but not antibodies? How old are you? Thanks Dave

      • Vicki says:

        Hi Dave,

        I’m 26. I’m not sure what the total thickness is but the doctor told me I would have 298 after surgery which is just below their usual 300 limit (they said their limit is more conservative than others which I think is 250) and it would be unlikely they could do any enhancements after the surgery. I’ve been monitored for lupus because I have reynauds and some blood work results that have indicators of lupus (ie high white blood cell count). My mom was also recently diagnosed with it.


        • Dave Allamby says:

          hi Vicki. I think there is no real difference between 298 and 300, which I agree is the right limit. However there is little hard science to get that number, but that is the figure most of us use. In view of your possible lupus, you might consider the 4th generation Starr ICL, which is available in toric forms to also correct astigmatism as well as your high level of short-sight. This avoids layering your cornea and possible healing complications (very hard to say if that would actually happen, but you do have abnormal white cell count so some immune system irregularities). The ICL (intraocular contact lens) lives within the front of the eye, between the cornea and iris. The main risk of ICL is development of cataract.
          Regards, David

  16. Jean says:

    I have been wearing RGP lenses for over 10 years now. The prescription in my RGP lenses was stable at -8.5 the entire time. Once I started looking into laser surgery I heard I would need to be out of my RGPs for over a month, so I asked for soft contacts. 3 weeks later I was told my prescription is now -12.5 and I am no longer a good candidate for LASIK. My corneas are around 525 each in thickness and I have net been told I have large pupils so I assume they are average size. Do I have any other options besides PIL/OIL as these are too expensive for me and I don’t like the idea of having a lens inside my eye forever.


    • Dave Allamby says:

      Hi Jean
      Unfortunately, you would still have significant myopia and need glasses after LASIK, based on your numbers and with an average pupil size. Just too much myopia, sorry!
      Best regards

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