In order to decide whether you're a good candidate for LASIK, your eye doctor will examine your eyes to
determine their health, what kind of vision correction you need, and how much laser ablation is required.
Just as in a regular eye exam, he will use instruments such as: an auto keratorefractor (to determine your
prescription and accurately assess your astigmatism); a Slit Lamp (to look into the back of the eye under
high magnification); and a tonometer (to determine intraocular pressure — if it's high, this may be an early
sign of glaucoma).

Your doctor will also look for signs of dry eye disease, if excessively dry they may need to be treated before
LASIK can be performed.

A corneal topographer is the next step. This device photographs your eye and creates a kind of “map” of
your cornea. No one has a perfectly rounded cornea, and the topographer will display the corneal
irregularities and the steepness or flatness that the surgeon must correct.

Your corneal thickness will be evaluated as will the quality of your cells on the inner surface of the cornea
using a “Specular Microscope”.  It tells  how safe is it for you and how much correction can be done safely.  

Your doctor will also use a new “Wavefront” device, termed the “abberometer” which send waves
through the eye to provide an even more precise map of the aberrations that are affecting your vision.

Finally, the doctor will question you about any health problems you have or medications you take. Some
health conditions will disqualify you altogether for LASIK, but others may just postpone the procedure until
a later date.