The modern era of laser skin resurfacing began in the early 1990’s. At that time the primary laser being used was the carbon dioxide (CO2) laser. One of the problems that was encountered with the then available methods of delivery was excessive thermal (heat) energy. To compensate for this undesirable side effect, alternative delivery systems were produced. These included scanners, which would move the beam around a given area typically in a spiral shape. The theory behind this was that if the laser beam were kept moving the dwell time (the amount of time that the laser was kept in contact with the skin) would be reduced thus reducing the degree of thermal injury. Another technology that was utilized for the same purpose was delivering the laser energy in extremely short pulses. This did produce less heat damage to the skin and actually proved to be superior to the scanned technology.
Prior to the advent of laser resurfacing the main modalities that were used for this purpose were dermabrasion and chemical peels. Dermabrasion has been used since the 1950’s and involved mechanically removing skin typically using a wire brush or a microstudded cylinder called a fraise, which would be set into rapid rotation using a power handpiece. Dermabrasion was used effectively for the treatment of lines, wrinkles, and acne scars for many years. The problem with dermabrasion was consistency as it was very user dependent. Dermabrasion was, also, very messy with significant blood splatter. With the increase in individuals with a diagnosis of HIV or hepatitis there were various reasons why dermabrasion lost popularity and laser resurfacing gained favor.
The other popular method that existed prior to laser skin resurfacing was chemical peeling. This typically entailed the application of an acidic compound such as TCA (trichloroacetic acid) or phenol acid (a stronger acid solution) based peels. These peels chemically remove layers of skin to make it smoother. The depth of the peel would be dictated by the strength of the solution applied. Ten to thirty percent TCA peels are typically lighter where phenol based peels produce a deeper wound that takes longer to heal. Other materials, such as Jessner’s solution, are sometimes added to TCA peels to boost their strength. Current thinking is that the croton oil added to phenol based peels may have more to do with the peeling process than the phenol itself.
The desire to achieve greater precision with skin resurfacing made resurfacing with lasers very attractive. Lasers resurface skin through a process of vaporization rather than mechanically or chemically as we did with dermabrasion and chemical peels.
In the mid 1990’s another wavelength (or color) of laser was introduced for skin resurfacing, known as the Erbium: YAG (Er: YAG) laser. The basis for laser resurfacing is a process of selective absorption of the laser energy by the water in our skin. Water makes up 70% of our skin. The difference between the CO2 and Erbium: YAG laser is that the Er: YAG is absorbed 13 times better by water or 70% better by our skin. This enhanced absorption of the Er: YAG laser means that the vaporization process is more efficient. Therefore, the amount of energy that just heats tissue but doesn’t vaporize it is greatly reduced. This, in turn, means a much smaller zone of thermal injury (heat damage) that is invisible. The Erbium laser has been described as more of a what you see is what you get because the visible injury that is produced more closely correlates with the actual depth of injury.
One of the drawbacks to CO2 laser resurfacing is trying to gauge the depth of the injury produced when you can’t see the extent of this heat injury. The physical characteristics of the Erbium laser are such that the surgeon can much more accurately assess the depth of treatment. The greater the depth of treatment the more prolonged the healing time and the greater the risk of side effects. To some degree, deeper lines, wrinkles and acne scars can be more successfully treated with a deeper treatment than a more superficial one. However, if the depth of treatment is too great then the incidence of scarring and/or hypopigmentation (loss of pigment) is increased. The greater control of the depth of the injury by the surgeon makes it a much more reliable and safer procedure for the patient.
Over the years, there have been two fallacies that have been propagated in laser resurfacing literature that I would like to address. One is the misconception that the Erbium laser is better for light lines or more superficial acne scares, and the CO2 laser is better for deeper problems. The truth is that for the last 15 years I have been able to treat superficial and deeper skin texture abnormalities as well as or better than the CO2 laser with less redness, less prolonged redness and less potential for hypopigmentation.
The other misconceived notion is that the heat injury associated with the CO2 laser equates to more remodeling and tightening of skin collagen. In my opinion, it is the depth of the injury that stimulates collagen more so than heat. Chemical peels and dermabrasion don’t produce heat, but we see collagen remodeling with them as much as we do with CO2 resurfacing. My feeling is that if I can provide my patients with a better outcome and lessen the potential for side effects I will do so. That is why I prefer the Erbium: YAG laser over the CO2.
Finally, let’s discuss the currently popular fractionated lasers. The idea here is to produce islands of treated vs. untreated skin allowing for rapid healing and less potential for side effects. Both the Er: YAG and CO2 wavelengths are used in fractionated laser resurfacing. The problem is that in order to produce little to no downtime the results that are seen are quite subtle. If the energy levels are turned up to maximize the improvement then the healing time is still in the range of 7-10 days. The same can be accomplished with the Erbium laser. With lower energy you can heal over a weekend, and with higher energy we can treat more advanced wrinkles and scars, or we can treat in between the two.
The Erbium: YAG laser allows us the latitude to match up the parameters to the patient’s needs in order to minimize their downtime and maximize their results. An advantage of the Er: YAG ablative laser resurfacing vs. fractionated lasers is the greater impact on the aging and sun damaged epidermis (top layer of skin) that is not treated as thoroughly by fractionated lasers.
(Authored by Dr. Michael Jasin)