Laser microscope peers beneath skin surface without causing damage

In use since late 2003 at Universitätsmedizin Berlin's Charité Campus, the Stratum microscope (OptiScan Ltd., Melbourne, Australia) allows researchers to look into the skin without damaging it in order to analyze the distribution and absorption of topical preparations such as sunscreens and makeup, as well as the body's utilization of systemic drugs.

"It's no substitute for biopsies," Dr. Lademann says, "but you get a lot of information about the skin's surface because the system uses a UV laser operating at 488 nm."

As such, the laser penetrates no deeper than approximately 200 microns.

Sunscreen Regarding sunscreen, his analysis has shown that absorption depends largely upon skin topography.

"By using the system," he adds, "you can check different formulations and see how they are distributed on the skin."

Since some formulations diffuse better than others, research like Dr. Lademann's could prove important to manufacturers of sunscreens, who must balance consumers' desires for less oily preparations with adequate SPFs.

Cellular route? Another topic of interest to Dr. Lademann's department is investigating penetration kinetics and pathways of topical preparations which should pass to the skin barrier (Lademann J et al. Laser Physics. 2003;13(5):756-760.).

"In other words," he explains, "is there a cellular route, which means that the substances are going inside the lipid layers and penetrating into the skin? Or are substances penetrating through the hair follicles? To investigate these questions, you must do it in vivo. You cannot use excised skin or skin substitutes. You also cannot do it through biopsies because it's not possible to take a lot of biopsies from the same volunteer to investigate the kinetics involved. But through laser scanning microscopy, you can distinguish between the penetration in the lipid layers and in the hair follicles."