What is the highest prescription for Lasik?

There is not really any sort of "guardrail" number of diopters that can be successfully AND safely treated with LASIK. In general, the higher the prescription to correct your myopia (nearsightedness) and astigmatism, the more stress you are creating on your cornea over the rest of your life. This is because how much corneal tissue gets removed in laser vision correction is proportional to the desired degree of correction: the more myopic you are, the more thinning of your cornea is necessary. Remember that the cornea does not grow back -if it did, the myopia correction would slowly disappear.

When LASIK and PRK were first approved by the FDA in the 1990s for the various excimer lasers wishing to go market, nobody had a good feel for this. So laser vision correction to this day is "approved" for up to as much as -12 diopters (depending on the particular laser company). But the last 20+ years of experience have shown that the possible long-term problems of LASIK/PRK are much more likely as you approach and pass the -8 D. level. This does not mean that -8 D. is the effective "limit" but that many fewer people with normal corneas and myopia in the lower and moderate ranges had issues long-term as compared to those treated with higher myopic Rx's. There are several factors to consider in deciding the upper limit of safety in a particular patient: age, corneal thickness, corneal symmetry, tear production, and the degree of astigmatism are some of the more common. I often see patients with a fairly low -3 D. who are not good candidates but then might see somebody who is -7 D. and is a good candidate. These issues are long-term ones -they are not at all something that would be apparent in the first few years after a very high myopic Rx treated where the patient thinks it was a success!

_Written by J. Trevor Woodhams, M.D. - Chief of Surgery, Woodhams Eye Clinic