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 Dr. Nuijs |
The procedure involves using a tightly focused near-infrared-pulsed laser (Philips Research, Eindhoven, Netherlands) that has a short pulse duration in the picosecond range and causes optical breakdown inside the tissue. Lesion size ultimately reaches 100 to 200 microns in diameter, because of a generated cavitation bubble that increases the area of damage.
INVESTIGATING OUTCOMES Outcomes of the treatment have been investigated using a prototype device, initially in ex vivo skin that showed proof of principle in creating isolated lesions at a targeted depth within the dermis, and subsequently in human trials that showed the treatment was safe, well-tolerated and induced collagen remodeling.
 Dr. Verhagen |
"The new technique we've described, despite being an ablative collagen remodeling technique, is able to avoid all damage to the epidermal layers, therewith eventually allowing for a larger proportion of the dermal collagen to be affected and for high efficacy without the risk of severe side effects. Of course, the fact that the epidermis is not affected limits the applicability of the technique as, for instance, it is not expected to be effective for removing pigmented lesions (age spots)," Dr. Verhagen says.
STUDY PARAMETERS AND RESULTS The clinical study was performed on buttock skin of five paid volunteers, age 20 to 65 years, with Fitzpatrick skin types II and III. The targeted lesion depth was 190 microns, and four different density coverages were tested — 2.5, 5, 10 and 20 percent.
Patient ratings of treatment discomfort ranged from not perceptible (40 percent) to slightly painful (40 percent) at worst, with most subjects rating higher densities as more acceptable. Post-treatment sequelae consisted only of mild, transient erythema and edema resolving within 30 and 60 minutes, respectively. However, the treatment also induced petechiae, which persisted for up to 10 days.
"Petechiae severity increased with increasing percentage coverage and depended on treatment depth. By keeping coverage density at 10 percent and with adjustments of the optical coupling of the device to the skin and treatment depth, problems with petechiae have been largely avoided in further testing performed on volar forearm skin," says Dr. Nuijs, a research fellow at Philips Research.
Evaluation of the treatment effect was determined through histological evaluation of skin biopsies taken before and immediately after treatment and again after three, seven, 30 and 180 days. Hematoxylin and eosin (H&E) staining showed the presence of partially collapsed cavities within the dermis after three days, while use of Herovici staining indicated formation of strands of new collagen III at day 30.
"The appearance of the new collagen corresponded to the depth of the created lesions and was absent in control biopsies," Dr. Nuijs says.
According to Dr. Verhagen, no clearance by the Food and Drug Administration is pending as of yet, and the next studies are intended to show the efficacy in facial wrinkle reduction in a clinical setting on a limited number of volunteers.
DISCLOSURES:
Drs. Nuijs and Verhagen are salaried employees of Philips, but neither reports any other direct financial interests.
