One of the most commonly asked question regarding laser eye surgery is whether or not it can correct high prescriptions. The simple answer to this question is yes it can.
Over the past ten years, the treatable range for laser eye surgery has increased dramatically and the procedure can now treat very high prescriptions. Very few people will now be deemed unsuitable for laser surgery on the basis of their prescription being too high and this is especially true if you are short-sighted. Laser eye surgery cannot, however, treat long-sightedness (plus prescriptions) as effectively as short-sightedness
Laser eye surgery can correct the sight of those who are long sighted, short-sighted or who have astigmatism and there are differences in the treatable range, depending on which category you fall in to. There is also a difference in the range when comparing Lasik and Lasek, with Lasik generally being able to correct higher prescriptions. The following shows you the range for the different prescription types for both Lasik and Lasek.
Lasik eye surgery: Prescription range:
Short sightedness (myopia): -0.75 to -12.00DS.
Long sightedness: (Hypermetropia): +0.75DS to +5.00DS.
Astigmatism: Standard treatment: Up to +/- 3.00Dcyl. Wave front: up to +/- 6.00Dcyl.

Lasek eye surgery: Prescription range:
Short sightedness: (myopia):  -0.75 to -9.00DS.
Long sightedness: (Hypermetropia): +0.75DS to +4.00DS.
Astigmatism: Standard treatment: Up to +/- 3.00Dcyl. Wave front: up to +/- 6.00 Dcyl.

Additional Points about treating high prescriptions:

• As you can see from the above, if you have high astigmatism (greater than +/-3.00) then your surgeon will insist that you have Wavefront laser eye surgery. Laser eye surgery for astigmatism is improving all the time and it is currently more accurate than ever.
• If you have a high prescription then you are more likely to require laser re-treatment. The reason for this is that higher prescriptions require a bigger change in the shape of your cornea to correct your vision. The more you change the shape of something (your cornea) the more likely it is to revert back to some degree to its original state. It is extremely rare that it reverts back to the original prescription and typically it is just a fraction of what it originally was. Most clinics will do the re-treatment for free.
• The biggest limiting factor in treating high prescriptions with laser eye surgery is your corneal thickness. The cornea is the part of your eye that is reshaped during the procedure and this process involves removing some corneal tissue. The higher your prescription the more tissue (cornea) has to be removed and so consequently you need a thicker cornea. Your surgeon will not perform the surgery if there is not enough corneal thickness to do so safely.
• The recovery time is likely to be longer if your prescription is higher and you may be in slightly more discomfort following the procedure.
• The risks of laser eye surgery are pretty much the same regardless of how high your prescription is.
• Some laser eye surgery clinics will charge more if your prescription is higher.

In summary, laser eye surgery can treat high prescriptions extremely effectively. The range of prescriptions available to laser eye surgery will cover approximately 95% of the population meaning very few people will be beyond the treatable range.