Who is not suitable for laser eye surgery?

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.

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.

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.