LHE and Skin Rejuvenation

Skin rejuvenation is a broad term that usually refers to the anti-aging effects achieved through treatment by a dermatologist or aesthetician. A more comprehensive definition divides the field of skin rejuvenation into several categories; the removal of pigmented lesions known as age or sun spots, the removal of vascular lesions also known as spider veins, the improvement of skin texture, and the smoothing of lines and wrinkles. Although LHE employs a singular treatment type for all skin rejuvenation elements, the underlying processes that bring about the results are different.

The theoretical basis for photorejuvenation lies in the principles of selective photothermolysis combined with the photothermal stimulation of new collagen growth. The stimulation of new collagen growth occurs in response to a mild thermal insult in the reticular and papillary dermis.

Removing Age Spots

Since selective photothermolysis is based on the absorption of light by target chromophores, it is necessary to choose the most appropriate chromophore for the application being applied and the desired outcome. Then apply the optimal wavelength spectrum and pulse duration for that chromophore. When removing age spots for example, the targeted chromophore is melanin, while in the case of vascular lesions the most prevalent chromophore is hemoglobin.

Given that both melanin and hemoglobin absorb light energy in the visible spectrum, LHE uses light in the benign 400 – 1200nm light spectrum. This allows for effective coagulation of the target while optimizing safety by completely avoiding the UV exposure present in lower wavelengths. In addition, the added heat value of LHE further raises the temperature achieving coagulation with lower light fluences.

Once coagulated the body’s natural healing process works to remove the lesion, which then scabs and drops off or is absorbed by the skin.

The limited flash duration of 10ms insures the safety of the surrounding tissue by being greater than the TRT of epidermis while not exceeding the TRT of the fine blood vessels being treated.

Improving Skin Texture

As mentioned above, the LHE effect on skin texture is based on the stimulation of new collagen growth that will help replenish and even out the shrunken dermis layer.

Near and mid infrared wavelengths (700 and above) are directly absorbed by intra and extracellular water. The resulting mild thermal insult to the papillary and upper reticular dermis leads to fibroblast activation. Fibroblasts are the cells of connective tissue responsible for making the collagen and elastin fiber cells found in the connective tissue of the dermis.

The creation of new collagen and connective material caused by the thermal insult and subsequent fibroblast activation occurs over a period of a few weeks to a few months. This wound healing response leads to improvement in skin texture and the smoothing of fine lines that has been shown to hold up over several years if patients practice stringent sun protection.

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