Histological analysis of the hair follicles exposed to the laser suggested that hair follicle response to laser treatment is fluence-dependent, and therefore, hair removal could be achieved through different mechanisms, including modification of hair cycle, hair follicle miniaturization, or hair follicle destruction. If low fluences accelerate anagen-catagen hair follicle transition leading to temporary hair loss, […]

Observations made at extended periods after various laser treatments revealed further progression of histopathological changes in the hair follicle. For instance, seven days after the treatment with ruby laser at 11 J/cm2, damaged follicular epithelium was observed with increased eosinophilia and pyknotic nuclei, suggesting the development of cell death in the hair follicle. Twenty one […]

In studies using various laser systems at varying fluences, coagulation of cellular proteins in hair follicles was observed after irradiation at high fluence levels. In skin samples biop – sied immediately after the normal-mode ruby laser pulses at fluence of 30-60 J/cm2, selec­tive but heterogeneous follicular damage was detected, consisting of thermal coagulation and asymmetric […]

Because laser light energy is transformed into heat upon absorption by melanin, the change in tissue temperature, and the rate and time period of this temperature rise deter­mines the tissue response. In a study using real-time thermal imaging, the temperature change in response to ruby laser was determined to be in a range of 5-10°C […]

The principle of selective photothermolysis that applies to laser hair removal indicates that by using a combination of the appropriate laser wavelength, pulse duration, and fluence targeted to a particular chromophore can selectively affect the target tissue. For the hair follicle, melanin serves as the endogenous chromophore located in the pigment-producing melanocytes of the hair […]

The factor most important to determining the hair follicle sensitivity to laser treatment is the melanin pigment of the hair follicle. Therefore understanding when, where, and how melanin is formed is important in understanding laser efficiency, as well as in determining the temporary or permanent effect of laser on hair reduction. Hair color is determined […]

Understanding hair follicle components and hair cycle is important to understanding the overall sensitivity and reaction of follicles to laser exposure. The hair follicle is a multicellular structure that generates an organ-specific product—a pigmented hair fiber, as a result of tightly coordinated interactions between epithelial, mesenchymal, and neuroectodermal cells of the follicle. The hair follicle […]

Natalia V Botchkareva1,2 and Gurpreet S. Ahluwalia1 1The Gillette Company, a wholly owned subsidiary of The P&G Company, Needham, MA, USA 2School of Life Sciences, The University of Bradford, Bradford, UK 9.1 Introduction 218 9.2 Hair Follicle Anatomy and Hair Cycle 218 9.3 Hair Pigmentation 222 9.4 Principles of Laser Hair Removal and Factors Affecting […]

The IPL devices use polychromatic light with a broad wavelength spectrum (590-1200nm) [103-107]. It is difficult to compare efficacies of the IPL devices across studies due to dif­ferences in number of treatments, treatment sites, and varying follow-up periods. Fodor et al. reports that most complications were observed in patients with skin types IV and V […]