Laser Resurfacing 101
What is laser resurfacing? The simplest explanation is that it is the use of a laser to remove a portion of the outer layers of the skin. If 100% of the skin surface area is removed we call it full field resurfacing. If a portion of the outer layer is removed leaving some portion untreated it is called fractional resurfacing. It all started in the mid 1990’s with the introduction of the carbon dioxide laser which has a wavelength of 10,600nm and an absorbing chromophore of water and is used to vaporize tissue. Carbon dioxide resurfacing became very popular and replaced chemical peels and dermabrasion in many practices. There were many devices from different manufacturers which caused some tissue ablation and left some residual thermal damage. These were full field devices that most of the time were used to take off 100% of the epidermis and some of the dermis. The energy used and the number of passes controlled the depth of treatment. Short term results were often fantastic with wrinkle eradication and tissue tightening. Unfortunately, longer term studies showed hypopigmentation in a large percentage of patients. These pigmentary complications and the considerable downtime created for the patient led to the demise of “full field” carbon dioxide laser resurfacing around the turn of the century.
Erbium:YAG lasers (2940nm) were introduced around 2000 and have a higher water absorption coefficient than carbon dioxide lasers (about 10 times more efficient). This means that they ablate tissue with much less thermal damage (5-10 microns). Complications were fewer yet downtime appeared to be similar to carbon dioxide systems. Combination systems of carbon dioxide and erbium lasers were popular for a short time (Derma-K, Lumenis lasers, Yokneam, Israel). Variable or long pulse erbium lasers (Sciton Inc, Palo Alto, CA) allow variation of pulse width allowing control over the amount of residual thermal injury produced for a given amount of tissue removal. These variable pulse Erbium:YAG systems produce skin tightening and wrinkle reduction similar to carbon dioxide lasers with a much shorter period of erythema and much lower risk of hypopigmentation.
Other wavelengths for skin resurfacing have been introduced (2780nm and 2790nm) (Cutera Lasers, Palomar Lasers) which allow variable degrees of thermal damage and ablation settings but with limited commercial success.
In 2004 Manstein et al introduced the concept of fractional photothermolysis. These lasers resurfacing treat a small ‘fraction’ of the skin at each session, leaving skip areas between each exposed area. This was first performed using non-ablative fluences at 1550 nm (Reliant technologies Mountain View, CA – now Solta Medical). These non-ablative fractional lasers created a column of thermal damage with intact epidermis. Healing occurred from deeper structures as well as from adjacent structures. Advantages include avoidance of an open wound and very low risk of pigment disturbance or scarring. Disadvantages include the need for multiple treatments and somewhat less clinical response than with full field ablative resurfacing. There are now many manufacturers with similar non-ablative fractional devices with wavelengths of 1440nm 1540nm and 1550nm.
Fractional ablative resurfacing with carbon dioxide, erbium, and YSGG systems were then introduced which ablate a channel into the skin. These devices differ not only in wavelength but in system power, spot size and amount of thermal damage created adjacent to and deep to the ablated hole. As with the non-ablative fractional systems direct comparisons between devices are difficult as devices differ in power output, spot size, density and degree of thermal damage but similar degrees of injury should produce similar clinical results.
The newest wavelength to be introduced into the fractional arena is the Thullium (1927nm) by Solta Medical. This non-ablative fractional device is especially effective in removing superficial pigment.
Full field ablative resurfacing and both fractional ablative and non-ablative systems remain very popular in clinical use at this time.
Dr. Jason Pozner