To characterize the efficiency of light interaction with biological tissue (inducing a pho­tochemical reaction, temperature increase, evaporation, thermal mechanical breaking, etc.) besides choosing the wavelength of light, its energetic parameters are also important. Two major parameters are typically used: energy and power. Energy is the ability of light (as well as other forms of energy, […]

Physicians who apply light in phototherapy or vision science classify the whole light spec­trum (i. e., from 100 nm to 1000 pm) based on its major mechanism of interaction with bio­logical cells and tissues. In particular, light spectral ranges are described as: ultraviolet (UV) light—UVC, 100-280 nm; UVB, 280-315 nm; and UVA, 315-400 nm; visible—400-780 […]

3.1.1 Electromagnetic Waves and Photons Light is the common name of electromagnetic radiation (EMR) that we can see. Lamps, lasers, and light emitting diodes (LEDs) that generate light can also emit EMR, which is not visible. However, they have specific features characteristic to the visible light, such as photochemical action for the shorter wavelengths (violet […]

Gregory B. Altshuler1 and Valery V. Tuchin2,3 1Palomar Medical Technologies, Inc., Burlington, MA, USA 2Institute of Optics and Biophotonics, Saratov State University, Saratov, Russia 3Institute of Precise Mechanics and Control of RAS, Saratov, Russia Gurpreet S. Ahluwalia (ed.), Cosmetic Applications of Laser and Light-Based Systems, 49-123, © 2009 William Andrew Inc. 3.1 I ntroduction Skin […]

The fundamental understanding of the effects of photodamage and aging on skin that has occurred over the past few decades has led to the identification and commercialization of various technologies that have a mechanistic rationale for potential treatment effects, includ­ing reversal of the appearance of fine lines and wrinkles and pigmentary disorders. These range from […]

Intrinsic or chronological aging occurs in all organs and cells in the body, including skin, and some of the major processes that are involved span cellular senescence, decreased metabolic capacitance, and diminished repair processes, including DNA repair as well as stress response [38]. The summation of these alterations in skin leads to clear physiological changes […]

It is well-accepted that chronic UV exposure is one of the primary drivers for changes in the structure and function of skin that can be visualized as increased fine lines and wrinkles, altered pigmentation, and physical property changes. These changes, particularly in facial skin, can be detected at the structural, cellular, and molecular levels. Biophysical […]

Over the course of an individual’s life, human skin undergoes a steady process of morpho­logical, structural, and biochemical alterations that are characterized as fine lines/wrinkles, texture, uneven skin tone, hyperpigmented spots, and loss of elasticity and resilience [16]. There are several working theories on the key causative scenarios to help explain changes observed in the […]

The morphology of skin is comprised of two primary layers of viable tissue that covers nearly the entire surface of the body [1,2]. These layers include the epidermis and dermis interspersed by a basement membrane, all of which reside on a subcutaneous fat layer or hypodermis. Residing in the skin are numerous structural appendages, including […]