L–M
Langer’s lines The natural linear pathways, also
called cleavages, of the fasciae fibers (connective
tissue layer beneath the SKINthat covers the mus-
cles) throughout the body. Langer’s lines resemble
a topographic map when overlaid on an outline of
the human body. Each person has a unique con-
figuration of Langer’s lines, though general pat-
terns are common across individuals. Alignment
with relevant Langer’s lines is one of several fac-
tors a surgeon considers when planning an OPERA-
TION’s incision. Surgical incisions that parallel
Langer’s lines tend to require less suturing and to
heal with less obvious scarring than incisions that
run counter, and particularly perpendicular, to
Langer’s lines. Wounds from cuts or punctures are
often more severe when they occur in opposition
to Langer’s lines, tending to gape and tear more
than wounds that parallel Langer’s lines. The RASH
or eruptions of some skin conditions, such as
PITYRIASISrosea, follow Langer’s lines.
See also DERMATOME.
laparoscopic surgery See MINIMALLY INVASIVE SUR-
GERY.
laser surgery Any OPERATIONin which the sur-
geon uses a device that focuses high-intensity
lightwaves that generate heat to cut or ablate
(destroy) tissue. Laseris an acronym for “light
amplification by stimulated emission of radiation.”
Lasers came into common use in medicine and
surgery in the 1960s; the first applications were
for the repair of detachedRETINA.
The lightwave emission of a laser differs from
ordinary light because it is
- all one wavelength (monochromatic)
- organized and unified
- directional and concentrated
There are different types of lasers, classified
according to the mechanism by which they pro-
duce lightwaves, the length of the lightwaves, and
the pattern of emission (continuous or pulsed).
The different wavelengths and pulse patterns of
emitted light permit targeted use of lasers from
making incisions (cutting) to treating discol-
orations of the SKINsuch as a port wine stain
BIRTHMARK. The laser’s lightwave determines what
tissues will absorb the light and what tissues will
allow the light to pass through them. For exam-
ple, the BLOODin blood vessels absorbs the yellow
light of the pulsed laser, though the pigment of
light-colored skin does not. Most lasers emit light-
waves in the infrared spectrum; the “cool” lasers
emit lightwaves in the ultraviolet spectrum.
Laser lightwaves, like other lightwaves, can
travel via fiberoptics, allowing the surgeon to
direct the laser emission to a specific location,
even one that is deep within the body. Laser sur-
gery requires the surgeon to complete specialized
training and requires specialized equipment and
facilities for safe use.
Surgical lasers have increased options in all
areas of surgery but have revolutionized two areas
of treatment in particular: ophthalmologic (EYE)
surgery and dermatologic (skin) surgery. The sur-
geon can so precisely focus and target the laser’s
beam that any incidental damage to surrounding
tissue is nearly nonexistent. Laser surgery inci-
sions tend to heal with minimal scarring. The heat
the laser generates kills BACTERIAon the skin at the
incision site, reducing the risk for postoperative
INFECTION. As well, the intense heat instantly seals
blood vessels to reduce bleeding at the site of the
incision, making the surgical laser the instrument265