Laser treatment for acne
Why does it matter? Acne is one of the most common dermatological conditions affecting the majority of people at some time in their life. It often results in significant sequelae including negative psychosocial effects [1]. Traditional treatments include tropical retinoids, topical/oral antibiotics, salicyclic acid containing agents, etc. Severe nodulocystic acne is generally treated with oral isotretinoin, but the use of this medication is limited by potential side effects. An ideal treatment might produce isotretinoin-like effects without subjecting the patient to the side effects. When histology of skin samples obtained from patients on isotretinoin is examined, one major finding is the sebaceous gland atrophy and destruction that results from the use of this drug [2,3]. Lasers particularly at wavelengths near 1720 nm are of interest for targeting fat/lipid rich tissues such as sebaceous glands due to the high absorption coefficient of human fat and low water scattering and absorption[4].
What is our solution? We have developed an all-fiber laser at 1708 nm close to the ideal ~1720 nm wavelength [5] . In our study, we show that our laser is capable of selectively damaging lipid rich tissue using an ex vivo porcine skin tissue cross-section consisting of epidermis, dermis, and subcutaneous fat. We show that for the same fluence level, no thermal damage was observed in the epidermis or dermis while the subcutaneous fat layer was seen to be thermally damaged. Then, as a potential application of the 1,708 nm light for the treatment of acne by thermally damaging sebaceous glands, we treated ex vivo human skin, first without any surface cooling. While histological results for skin treatments without cooling showed thermal damage in the dermis at depths >1 mm, there was also clear injury to the epidermis that warranted the need for a cooling method to protect the epidermis. Therefore, a cold window-based cooling method was designed and built to spare thermal damage to the epidermis during treatment. Our histochemistry results for 1,708 nm laser treatments on human skin with contact cooling indicated thermal damage to sebaceous glands at depths of up to 1.65 mm into the dermis with no injury to the epidermis.
[1] A.S. Glaich, P.M. Friedman, M.H. Jih, and L.H. Goldberg, Treatment of inflammatory facial acne vulgaris with combination 595-nm pulsed-dye laser with dynamic-cooling-device and 1,450-nm diode laser. Lasers in Surgery and Medicine 38 (2006) 177-180.
[2] A.S. Zelickson, J.S. Strauss, and J. Mottaz, Ultrastructural Changes in Sebaceous Glands Following Treatment of Cystic Acne with Isotretinoin. The American Journal of Dermatology 8 (1986) 139-143.
[3] J. Goldstein, H. Comite, H. Mescon, and P. Pochi, Isotretinoin in the treatment of acne. Arch Dematol 118 (1982) 555-558.
[4] R.R. Anderson, W. Farinelli, H. Laubach, D. Manstein, A.N. Yaroslavsky, J. Gubeli, K. Jordan, G.R. Neil, M. Shinn, W. Chandler, G.P. Williams, S.V. Benson, D.R. Douglas, and H.F. Dylla, Selective photothermolysis of lipid-rich tissues: A free electron laser study. Lasers in Surgery and Medicine 38 (2006) 913-919.
[5] V.V. Alexander, K. Ke, Z. Xu, M.N. Islam, M.J. Freeman, B. Pitt, M.J. Welsh, and J.S. Orringer, Photothermolysis of Sebaceous Glands in Human Skin Ex Vivo with a 1,708 nm Raman Fiber Laser and Contact Cooling. Lasers Surg. Med 43 (2011) 470-480.