Biomedical Engineering Reference
In-Depth Information
( A )
( B )
Figure 8.16 Striae response ( A ) before and ( B ) after three treatments with 1540 nm stamping using 50% overlap.
Initially, the 1550-nm fractional laser (Fraxel re:store, Solta
Medical) was investigated in a small group of men with AKs
(52). These men underwent 5 nonablative resurfacing laser
treatments every 2 to 4 weeks. Energies ranged from 20 to
70 mJ during the treatment but the majority of treatments
were performed at 70 mJ. TL was 11 and 8-10 passes were per-
formed. A baseline biopsy was performed and then repeated at
the 3-month follow-up immediately adjacent to the initial
biopsy site. AKs were counted at 1-, 3-, and 6-month follow-up
visits. There was clinical improvement after each session,
although histologically, precancerous changes were still evi-
dent. At the 1-, 3-, and 6-month visits; actinic keratosis reduc-
tion from baseline was 73.1%, 66.2%, and 55.6% respectively.
With the introduction of the 1927-nm thulium fi ber fractional
laser (Fraxel Dual, Solta Medical), more AK treatment studies
began. This superfi cial wavelength selectively targets the epi-
dermis and upper dermis and was postulated to have greater
effi cacy in the treatment of the mostly epidermal AKs. Weiss
et al. studied 25 subjects with facial AKs receiving up to 4 treat-
ments with a 1927-nm fractional laser (Fraxel Dual, Solta
Medical) (53). One month after the fi nal treatment, average
AK clearance was 88.9%. At 6 months after treatment, it was
75%. They found this treatment to be effective and well toler-
ated by patients. Friedman et al. performed a split face laser
treatment of AKs using the 1550 nm in combination with the
1927-nm laser versus the 1927-nm laser alone (54). They
found that the side treated with 1927 nm alone had greater
clinical reduction in AKs as well as improvement in sun-
induced pigmentation. Furthermore, the 1927-nm laser was
also applied to the treatment of AKs of the lip, otherwise known
as actinic cheilitis (55). This condition is notoriously hard to
treat, prone to recurrence, and can be quite painful for patients.
Anolik et al. performed a retrospective chart analysis of a small
group of actinic cheilitis patients and found that after 1-2
treatments patients were improved by 50-75% or 75-100% as
rated by blinded, non-treating staff dermatologists (56).
The procedure was well tolerated by patients and had much
less side effects when compared with ablation, surgery, or
treatment with topical chemotherapeutic agents or immune
modulators. Unfortunately, whenever biopsies were per-
formed on clinically improved AK treated with NAFL, persis-
tent evidence of dystrophic epidermal cells was present. We
therefore cannot recommend NAFL as a stand-alone treat-
ment for AK at this time.
enhancement in delivery of topical
drugs and products
Research in this application of NAFL is still in its infancy.
Enhancement of photodynamic therapy (PDT) has been stud-
ied with NAFL. In a study by Ruiz-Rodriguez et al., patients
underwent a split treatment of perioral Fraxel 1550-nm resur-
facing and resurfacing plus PDT (57). Immediately after NAFL
treatment, methyl-5-aminolevulinate was applied to half of
the perioral area for 3 hours and then activated by a red light
source. After two treatment sessions, all patients noted greater
improvement in the side treated with NAFL and PDT. In my
practice, we often pretreat our PDT patients with 2-4 passes of
NAFL, which allows for faster penetration of topical levulinic
acid. This is especially helpful in areas like the arms and legs in
which incubation time with levulinic acid would otherwise be
hours. Enhancement of platelet-rich plasma (PRP) treatment of
the skin has also been studied in NAFL (17). The study showed
that when PRP was combined with NAFL with a 1550-nm laser
(Mosaic, Lutronic Co. Ltd, Seoul, South Korea), patient satisfac-
tion and skin elasticity increased while erythema index of the
skin decreased. Histologically, patients who were treated with
PRP plus NAFL demonstrated increased length of the dermal
epidermal junction, amount of collagen, and number of fi bro-
blasts compared with those treated with fractional laser alone.
conclusions
Fractional photothermolysis, and its application of NAFL skin
resurfacing, is still considered a leading groundbreaking tech-
nology. Both the stamping modes and the continuous motion
handpiece with rollers are effective methods to deliver the
energy. New understanding and advances in engineering have
 
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