Biomedical Engineering Reference
In-Depth Information
continued sculpting of the acne scar without an increase in
nonspecifi c thermal damage.
Patients should be advised that acne scars are always diffi cult
to treat by any method, and the patient rarely reaches the level
of satisfaction desired in a single surgical procedure. The same
is true for laser resurfacing, but additional laser procedures
add signifi cant degrees of improvement.
Table 6.3
The Average Decrease in Photodamage at 90 days
and 1 year after Full-Face Resurfacing
Area
90 Days (%)
1 Year (%)
Perioral
69
64
Cheeks
89
72
Forehead
80
48
Periorbital
79
52
Scars
Crateriform varicella scars and isolated acne scars can be
improved with spot laser resurfacing. The area around and
over the scar is vaporized with one laser pass. Additional passes
with the Er:YAG laser are concentrated along the edge of the
scar crater until it has been completely effaced.
Postsurgical (Fig. 6.25) and traumatic scars and skin
grafts (Fig. 6.26) can be dramatically improved if resurfaced
(66,67,109). It is best to wait until the scar has completely
healed (3-6 months) (Fig. 6.27). This is an artistic endeavor
and involves the vaporization of elevated tissue high points,
as well as skin tightening to elevate loose atrophic tissue.
This is often a process of trial and error, attempting various
maneuvers in small selective areas with observation of
tissue effects before deciding to use an approach in a larger
surface area.
was noted in two patients treated with the SilkTouch laser and
one patient treated with both. Weinstein (107) reports that
follow-up of her patients for as long as 5 years after resurfac-
ing has shown that improvement visible at 6 months was still
present at 5 years and that the overall results are indeed long
lasting.
In addition, 24 subjects were treated with the SilkTouch laser
on one side of the face and 35% TCA on the opposite, for cor-
rection of periorbital wrinkling. Using a scoring system of 1-5,
pretreatment scores were found to diminish 56% with laser
treatment versus 20% with chemical peeling at 6 months. The
outcome difference was statistically signifi cant. Posttreatment
erythema, however, lasted 4.5 months versus 2.5 months for
the respective groups.
Long-term follow-up of 12 patients having photodamage
treated with dermabrasion and followed for 6 months to 8
years showed that not only did cosmetic improvement persist
over these time periods, but the need for continued treatment
of premalignant and malignant lesions was virtually elimi-
nated. All patients were noted to have maintained a smooth,
supple skin with pigmentation slightly lighter than the adja-
cent nondermabraded skin. The problem of course is that
although this laser resurfacing can improve the appearance of
wrinkling by over 50%, the patient continues to age. We typi-
cally are seeing our patients back after 10 years asking for a
second laser resurfacing procedure.
Actinic Cheilitis
Actinic cheilitis has proved to be a condition for which CO
2
laser
therapy is considered the treatment of choice (69,110-119).
It can be successfully treated by performing a laser vermilion-
ectomy using any of the resurfacing lasers (108). This proce-
dure usually requires only one pass with the laser over the
vermilion surface and then spot treatment of persistently visi-
ble actinic damage. This has signifi cantly reduced postopera-
tive healing to approximately 10 days, in contrast to the 4 weeks
required when the conventional CO
2
laser was used in the past
(69,110-119).
Also, the risk of scarring is greatly reduced because the
extent of thermal damage is much less.
Actinic keratoses unresponsive to conventional treatment with
liquid nitrogen and topical 5-fl uorouracil can be treated by
removing the epidermis with one pass and then concentrating
treatment on visible dermal extensions using one of the resurfac-
ing lasers. This is especially useful on the dorsal hands and scalp
but may be a primary or sole indication for laser resurfacing.
other indications of the co
2
laser
Acne
Laser resurfacing can achieve signifi cant improvement in acne
scarring. The procedure can be made very precise by sculpting
the edges of the scars and vaporizing more tissue away only in
the areas of scar tissue while doing only superfi cial resurfacing
in the rest of the cosmetic unit being treated. The tissue-
tightening effects can achieve dramatic improvement in soft
atrophic scars with sloping walls (Fig. 6.20). Some “ice pick”
and bound-down scars should fi rst be removed with punch
excision, punch elevation, or punch grafting, with laser resur-
facing performed 6-12 weeks later if maximum improvement
is desired (Fig. 6.24) (108). Those not treated fi rst with exci-
sion will improve, but the degree of improvement achieved
will depend on the scar's depth and the operator's skill. In gen-
eral, a 30-50% improvement is the treatment goal. However,
a study using the Coherent UltraPulse CO
2
laser to treat
moderate-to-severe atrophic acne scars in 50 patients revealed
an average clinical improvement of 81% at 6 months after
treatment, with progressive improvement occurring during
that period (18).
We always treat acne scars with the Er:YAG laser after resur-
facing with the CO
2
laser. The use of the Er:YAG allows for
Pigmentation
Pigmentation irregularities such as postinfl ammatory hyper-
pigmentation or melasma can sometimes be improved with
laser resurfacing. It is very important to use tretinoin (Retin-A)
and hydroquinone for an extended period before and after
the procedure (120,121). Other lasers more specifi c for mela-
nin or medium-depth chemical peels are often preferable
because they do not require anesthesia and recovery time is
much shorter (122-126). Melasma responds variably, in a sim-
ilar manner to its response to other modalities (127). Usually
these pigment abnormalities are a secondary component of
treatment and not the primary treatment objective. If they are
the primary reason for treatment, care must be taken to ensure
that other, more pigment-specifi c therapies are not desirable
for whatever reason.
