You need to verify the vision requirements for the military or federal agency you are considering joining. It is very rare that 20/20 uncorrected vision is a requirement. Even US Navy Top Gun pilots do not have this requirement.
The current methods of permanent or semi-permanent vision correction include:
Lasik
A “flap” of the front of the cornea is created, moved aside, a laser removes tissue to reshape the cornea, then the flap is repositioned over the treatment area.
http://www.usaeyes.org/lasik/faq/lasik.htm
Bladeless Lasik
Identical to Lasik except the “flap” is created with a laser rather than a metal blade.
http://www.usaeyes.org/lasik/faq/all-laser-lasik.htm
PRK
The outermost layer of cells on the cornea is removed, and then a laser reshapes the cornea. The cells quickly reproduce and cover the treatment area.
http://www.usaeyes.org/lasik/faq/prk.htm
LASEK
Same as PRK, except the outermost layer of cells are saved and repositioned over the treatment area after laser sculpting.
http://www.usaeyes.org/lasik/faq/lasek.htm
Epi-Lasik
Same as PRK, except outermost layer of cells are separated from the underlying cornea with a special mechanical device and repositioned over the treatment area after laser sculpting.
http://www.usaeyes.org/lasik/faq/epi-lasik.htm
CK
A probe emits radio waves at spots along the edge of the cornea, causing tissue shrinkage that reshapes the cornea. Rarely used because of significant and 100% regression.
http://www.usaeyes.org/lasik/faq/lighttouch-nearvision-ck.htm
P-IOL
An artificial helper lens is added within the eye, either just in front or just behind the iris (colored portion of eye).
http://www.usaeyes.org/lasik/faq/piol.htm
RLE
The natural lens within the eye is removed and replaced with an artificial lens that corrects vision.
http://www.usaeyes.org/lasik/faq/lasik-cle-iol-rle.htm