Biomedical Engineering Reference
In-Depth Information
(
A
)
(
B
)
(
C
)
Figure 7.12
Fractional carbon dioxide for acne scars. (
A
) Before, (
B
) 3 months after one treatment, and (
C
) immediately posttreatment. (Cheek treated with
120-
μ
m diameter beams, 20% total coverage, and about 700-
μ
m depth.)
between 10% and 35% with microwound depths of 400-800
m.
A recent case report in improving the pliability and range of
motion in a patient with scleroderma also attests to the utility of
fractional lasers in improving scars (13).
μ
suggested that there is not a signifi cant difference in the charac-
teristics of the ablative profi le of a CO
2
laser in diseased versus
undamaged adjacent skin (31). However, a more promising use
of a ablative fractional device is enhanced delivery of a drug,
such as aminolevulinic acid (ALA) for photodynamic therapy
(32), topical chemotherapeutic agents, or immunomodulators.
Premalignancies
Although ablative lasers have been used to treat premalignant
lesions (actinic keratoses), the use of ablative fractional devices
to treat premalignant and malignant lesions of the skin is limited
because less than 100% of the surface area of the skin is treated.
Another potential issue is variability of the absorption charac-
teristics of normal versus premalignant or malignant skin.
Work examining the laser absorption characteristics of skin
with nonmelanoma skin cancer and actinic keratoses (AKs)
relative to normal skin was initiated by Togsverd-Bo et al. to
address this question. A small sampling of patients with AKs,
Bowen's disease, or superfi cial and nodular basal cell carcinomas
miscellaneous applications
Tuberous sclerosis lesions have been reduced by ablative frac-
tional techniques. In case series of three patients, the authors
combined pulse dye laser (PDL) and fractional CO
2
lasers
(20-40 mJ, 40% coverage) (33). Individual larger lesions were
“pre”-treated with pinpoint electrosurgery. The goal was to
reduce the entire fi eld of lesion density and volume. However,
no one lesion would be likely to respond 100% with this
approach. On the other hand, risks of hypopigmentation and
scarring are reduced versus deep conventional laser treatment
