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    Who is not suitable for laser eye surgery?

    Written by Mr Tom Flynn, Consultant Ophthalmic Surgeon
    • Three reasons why laser eye surgery may not be suitable for you
    • Your eye prescription
    • Thin or irregular cornea
    • Eye prescription is outside the safe range
    • Further reading


    Who is not suitable for laser eye surgery resize

    All Moorfields Private surgeons are committed to delivering excellent outcomes for our patients. Sometimes, for whatever reason, people aren’t suitable for laser eye surgery (refractive surgery) and it’s really important for us to identify this and counsel against having the procedure if it’s unlikely to have an excellent result.

    At your consultation you will be assessed thoroughly and your surgeon will let you know if you are suitable for laser eye surgery. If you’re not suitable, we can offer good alternative treatment options.

    Three reasons that patients may not be suitable for laser vision correction are:

    1.Your eye prescription is unstable
    People who are short-sighted (myopic) and wear glasses or contact lenses will know that the numbers on their prescription can change at successive optician visits in their teens and even twenties. This is due to growth of the eyeball, which usually stops by around age 18-21.

    When the eye prescription continues to change at successive optician visits, say 12-24 months apart, we say that the eye prescription is “unstable”. If we were to perform laser vision correction while the eye was still growing, we would not expect the result to last. In a similar way - we would not expect our children’s clothes to continue to fit them as they grow up.

    This is why Moorfields Private surgeons need to see evidence of stability in your eye prescription before offering surgery. Some variation between spectacle tests is normal, but if you are in your early twenties and there is a progressive increase in the amount of short sight, you will probably need to wait before having laser eye surgery.

    Understand what your eye prescription means here

    2. You have a thin or irregular cornea
    If you have a predisposition to corneal shape irregularity, this can be made worse by laser eye surgery, and a condition called corneal ectasia may develop. This occurs infrequently and can often be treated successfully without the need for a corneal transplant. But we are careful to avoid laser eye surgery in patients who may be at risk. At Moorfields Private, we have the latest equipment for detecting ectasia risk, as well as plenty of good treatment alternatives if your scans indicate that you are not suitable for LASIK.

    Who is not suitable for laser eye surgery (2)resize

    3. Your eye prescription is outside the safe range of treatment
    Laser vision correction works by reshaping the cornea to improve focus. As the laser reshapes the cornea it reduces the corneal thickness. The cornea needs a certain minimum thickness to maintain its shape, so it follows that there is a limit to how much reshaping (and thinning) can be done.

    The amount of laser treatment that can be safely applied depends on the thickness of your cornea to begin with, which varies quite a lot. For short-sightedness (myopia) the safe limit is usually around -8 to -10 dioptres. For hypermetropia, the safe limit is usually around +4 to +6 dioptres. Your surgeon will assess you and tell you whether your eye prescription falls within the safe treatment range for you.

    Other vision correction surgery options are available – read more about them here

    Speak to our enquires team about booking a consultation today on

    0800 328 3421

    or email 



    Mr Tom Flynn

    Written by Mr Tom Flynn

    Consultant Ophthalmic Surgeon