Webster's New World Medical Dictionary

laser
A powerful beam of light that is used in
some types of surgery to cut or destroy tissue.
laser surgery, Yag
The use of a laser to punch a
hole in the iris, in order to relieve increased pres-
sure within the eye. Yag laser surgery is an outpa-
tient procedure that may be used, for example, to
treat acute angle-closure glaucoma.
laser-assisted in situ keratomileusis
See
LASIK.
LASIK
Laser-assisted in situ keratomileusis, a kind
of laser eye surgery that is designed to change the
shape of the cornea to correct vision defects includ-
ing nearsightedness (myopia), farsightedness
(hyperopia), and astigmatism. LASIK is an outpatient
procedure that is done with numbing eye drops and
takes only minutes to perform. LASIK is similar to
photorefractive keratectomy, the major difference
being the way that the middle layer of the cornea is
exposed before it is vaporized with the laser. In PRK,
the top layer of the cornea, called the epithelium, is
scraped away to expose the middle layer underneath.
In LASIK, a flap is cut in the middle layer and the flap
is folded back.
Lasix
See 
furosemide.
Lassa fever
See 
fever, Lassa.
lateral 1
The side of the body or body part that is
farthest from the middle or center (median) of the
body. Typically, lateral refers to the outer side of the
body part, but it is also used to refer to the side of
a body part. For example, in references to the knee,
lateral means the side of the knee farthest from the
opposite knee. The opposite of lateral is medial. See
also Appendix B, “Anatomic Orientation Terms.” 
2
In radiology, a slang term for a lateral X-ray film.
lateral collateral ligament of the knee
The
ligament that straps the outside of the knee joint. It
helps provide stability and strength to the knee. See
also 
knee.