Ablative Laser Facial Resurfacing

14.1 Introduction

The laser has now become one of the most commonly used means of achieving facial rejuvenation [1]. Although other methods of resurfacing, such as dermabrasion and chemical peels, are still frequently used, the laser’s ability to offer controlled delivery of energy with more predictable results has led to its adoption by many plastic surgeons as the standard method of performing facial rejuvenation. This chapter will provide a brief overview of basic laser physics as it relates to the skin, a description of the lasers commonly used, a description of the technique used in laser resurfacing, and a discussion of the complications associated with laser resurfacing.

The first laser used for facial resurfacing was the carbon dioxide (CO2) laser [2]. Its continued use today stands as a testament to its durability as a technique that provides good results for the majority of patients. The wavelength of the CO2 laser is 10,600 nm and primarily targets water. The other laser used for facial resurfacing, the erbium:yttrium-aluminum-garnet (Er:YAG) laser, also has water as its primary chromophore. The wavelength of the Er:YAG laser is 2,940 nm, which corresponds to the

P.D. Ward ( )

Division of Facial Plastic and Reconstructive Surgery, Division of Otolaryngology – Head and Neck Surgery, University of Michigan, 50 North Medical Drive, 3C120 School of Medicine, Salt Lake City, UT 84132, USA e-mail: pdanielward@hsc.utah.edu

J.H. Maxwell

Department of Otolaryngology – Head and Neck Surgery, University of Michigan Medical School,

1500 E. Medical Center Drive, Taubman 1904 D, Ann Arbor, MI 48109-0312, USA

e-mail: jmhooton@med.umich.edu

peak absorption of energy by water, resulting in absorption that is around ten times greater than the CO2 laser.

Since the epidermis is approximately 90% water, delivery of light at wavelengths that target water results in heating of the water, which is vaporized with subsequent heat transfer to the surrounding extracellular matrix and the collagen therein. Delivery of heat to collagen in the skin leads to denaturation of the proteins and, as healing progresses, the formation of new collagen and other extracellular matrix proteins helps tighten skin and reduce rhytids. Delivery of too much energy, however, can lead to damage to the reticular dermis and an overabundant expression of collagen and subsequent scarring. Thus, choosing a proper amount of energy to be delivered to a particular region is a critical component of laser facial resurfacing, because delivery of too little energy results in inadequate treatment, and delivery of too much energy leads to scarring [1–7].

The amount of energy delivered by the laser is typically measured in joules and the amount of energy delivered by the laser per surface area of tissue is measured in joules per square centimeter. This latter term is defined as the fluence of the laser. In addition to the fluence of the laser, the other variable that is important is the pulse duration, which is defined as the amount of time that the tissue is exposed to the electromagnetic radiation from the laser. Complete cooling must occur between passes with the laser to minimize the chance that unwanted heat will be conducted to adjacent tissues and result in undesirable effects. The thermal relaxation time is the amount of time required for complete tissue cooling to occur. For the CO2 and Er:YAG lasers, a very high energy level is utilized allowing for a very short pulse duration, which is on the order of 1,000 Ps or 1 ms. The power density of

Reprinted with Permission of Springer, Berlin