Aging Skin: Light Is A Double-Edged Sword

As we grow older, our skin ages and loses its youthful appearance. Wrinkles show up around the eyes and lips, and age spots surface on the hands and arms.  Though some of these “photoaging” factors are natural and unavoidable, many of the visible signs of aging are caused by the sun’s ultraviolet (UV) radiation and can be avoided by taking certain precautions, like wearing protective clothing and using sunscreens.

When UV radiation hits the skin, specialized cells are triggered to produce the pigment, melanin, which then helps protect the skin’s outer layer (epidermis).  This tanning process is really just your skin’s built-in attempt to block the radiation from penetrating your skin.  UV rays that penetrate deeply into the dermis are capable of damaging the all-important collagen fibers that give the skin much of its structural integrity.

Because collagen is responsible for skin strength, elasticity, and suppleness—all signs of good skin health—its breakdown or deterioration leads to wrinkles that accompany the aging process.  In this way, light causes the skin to age prematurely.  This is the process known as photoaging.  Deep wrinkles, vertical creases, and loose or sagging skin are all classic signs of this process.

Given that photoaging results from chronic exposure to sunlight, it seems ironic that light can also play such a powerful role in reversing the aging process.  Photorejuvenation was recently defined in the medical journal Dermatologic Clinics as “the process of using laser and other light sources for restoring skin to a more youthful appearance.”  This special application of photodynamic therapy (PDT) has been shown to improve or reduce skin roughness, lentigines (small dark spots on the skin), sallow complexion, and fine wrinkles.


An International Pilot Study

Scientists from China and the United States recently collaborated on a pilot study to compare the efficacy of PDT and red light alone in the treatment of photoaging.  They enrolled 14 adults, all of whom had signs of photoaging skin.  PDT or red light alone was applied to the forearms.  The treated sites were then carefully examined using a number of methods (dermoscopy, the changes in straum corneum, hydration, transepidermal water loss).  In addition, various laboratory values were measured, and collagens and elastins were analyzed under a microscope.

The international team of researchers found that, after PDT or red light illumination, the appearance of photoaging lesions improved, hydration increased and water loss decreased.  The changes were more pronounced in the PDT group than in the red light group.  The signs of typical photoaging (solar elastosis damage) were improved in both groups.  Thus, PDT had a significantly more favorable impact on skin rejuvenation  than red light alone, as reported in the 22 February 2014 issue of Photodiagnosis and Photodynamic Therapy.


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Ji J1, Zhang LL1, Ding HL1, Wang HW2, Huang Z3, Wang XX1, Wang PR1, Wang XL4. Comparison of 5-aminolevulinic acid photodynamic therapy and red light for treatment of photoaging. Photodiagnosis Photodyn Ther. 2014 Feb 22. [Epub ahead of print]

Kutlu Haytoglu NS1, Gurel MS, Erdemir A, Falay T, Dolgun A, Haytoglu TG. Assessment of skin photoaging with reflectance confocal microscopy. Skin Res Technol. 2014 Feb 10. [Epub ahead of print]

Grether-Beck S1, Marini A, Jaenicke T, Krutmann J.  Photoprotection of human skin beyond ultraviolet radiation. Photodermatol Photoimmunol Photomed. 2014 Jan 16. [Epub ahead of print]


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