Reflecting on the Early Days of Lasers and the Vascular Era

The path from the early lasers of the 1980s to today’s devices has been anything but linear. Early adopters have pushed boundaries to advance the field, learning lessons along the way that have informed subsequent innovations. Modern Aesthetics March/April Guest Medical Editor Jill Waibel, MD, FACS, FAAD, sat down with 3 fellow pioneers in the field for an inspirational and reflective journey through the history of laser and light-based technology. This is the second excerpt from that conversation. (Editor’s note: This transcript has been lightly edited for clarity and conciseness).

THE EARLY DAYS OF LASERS

Dr. Waibel: How was the selective photothermolysis concept developed, and how did it change everything for laser?

Dr. Anderson: Photothermolysis is a simple idea that I hatched when I got really angry. At a lecture at Beth Israel Hospital in Boston, a group of people in plastic surgery and dermatology had been studying argon laser treatment for kids with port wine stains. They showed that, while it worked to a certain degree on adults, it resulted in a lot of burn scars in children. It struck me that, although they understood the wavelength needed to be absorbed by blood, they had not thought through the heat transfer. My background from Massachusetts Institute of Technology is physics and biology, and I just put two and two together and said: what is missing is a pulse of light—a short pulse that is absorbed by hemoglobin and targets those little abnormal blood vessels. I took the bus back to my apartment in Cambridge and scribbled out the equations necessary to do selective photothermolysis. It took a couple of years to build the first pulsed dye lasers, test them, and show that it works. That application—the pulsed dye laser in the yellow part of the spectrum—is still the gold standard for treating children with port wine stains. It opened a door to the idea that you can use light to do surgery, by heating things selectively on a microscopic scale. That was the first time that kind of selectivity had been there. It is a very simple concept: you need selective absorption, you need to pay attention to heat transfer, and then you get this magic bullet. The human body is made of small components. The ability to target those individually was fascinating. After port wine stains, the selective photothermolysis approach became the basis for tattoo removal, for treating many pigmented lesions, for laser hair removal, and even for glaucoma treatment, some retinal work, and cancer in the vocal cords. 

Dr. Ross: I used my first cwCO₂ laser in 1989 as a resident. When Dr. Leon Goldman used to say the laser was “a tool looking for a job,” the reason was it was not that great a tool. Selective photothermolysis really brought it into acceptance because it was no longer just vaporizing things like napalm in the forest. If you had the right fluence, the right pulse duration, the right target, and the right wavelength, you could have selective heating. That really changed things. I show patients with telangiectasias a video of a blood vessel being coagulated with a 532-nm long pulse laser, and I explain that the whole laser beam is much bigger than that blood vessel but that the rest of the skin stays cool. Probably more than a lot of other things, that did revolutionize the way we use lasers, because now we have this way to target the bad guy and spare the good guy.

Dr. Waibel: How cautious was the field in those early days?

Dr. Geronemus: Before selective photothermolysis, treating port wine birthmarks left patients with scarring and changes in pigmentation. Now, we can treat a newborn with impunity, but that was just a pipe dream back then. Safety is critical, and lack of concern for safety can also hurt the patient, hurt the device, and hurt the industry. In the late 1990s, early adopters were getting great results with scanning CO₂ lasers, but as those devices became more widely used by people who were less concerned about safety, the field imploded. After some national news stories brought to light the scarring and the changes in pigmentation that were negatively transforming people’s lives, that device and that technique basically fell by the wayside. It was resurrected subsequently with fractional treatments, but safety remains critical. 

Dr. Ross: There is a certain cavalier attitude about the lasers now because so many providers who use them and the devices are safer, but with that comes a sense of “nothing could go wrong,” and that is a problem. The first time I held a CO₂ laser to treat a wart as a resident, I was literally shaking with fear. Now, people think inputting certain settings will make the devices infallible. There is a lot of safety built into devices now, but we still need a better emphasis on training, caution, and slowly increasing settings. That is a big part of avoiding complications.

Dr. Waibel: I still have a healthy respect for the potential risks on any laser case. I look around the room to make sure the signs are all up, the glasses are on, and the fire extinguisher is under the sink.

THE VASCULAR ERA OF LASERS

Dr. Waibel: Moving on to the 1980s and ’90s, how did the pulsed dye laser transform vascular treatments and what have we learned?

Dr. Geronemus: I was one of the first investigators with a pulsed dye laser in 1984, and we really did not know what to do with it. Rox had shown that you can selectively damage a blood vessel, but it was my job and the job of other early adopters to put it into clinical use. To put into perspective how far we have come, we used to test patients with light therapy just to see what dose was safe because we had no idea as to the dosing, the energy fluence, and what should be delivered. It was trial and error. The process was very slow and laborious. The largest spot size we had was 5 mm. It was typically 0.3 Hz, so it was pretty slow. A patient with a birthmark on their arm would stay in New York for a week and we would treat them every day, one segment at a time. Now, you can treat an arm in a matter of minutes with a 15-mm spot and a repetition rate of 1.5 Hz. We began by treating adults and then, ultimately, teenagers, older kids, and younger kids. Now, it is best to treat these patients as newborns. I like to say, “Out of the hospital and into the office right away.” We have found that early intervention and frequent treatments make a very big difference. There seems to be a window of opportunity in treating these young babies, on both the face and other parts of the body, when it can be done safely and it can be done more effectively than ever before. We published a paper looking at 197 babies under the age of 1, with rather dramatic lightening and/or clearing.1 Subsequently, we began to treat them once a week, and more recently, I have been treating some newborns every day for a week. That is something we can do safely, taking advantage of the fact that they do not get the purpura or the bruising that one sees at older ages. It is also very good for patients who are traveling for treatments, who want to get things done very quickly. So, we have come a very long way. By no means are we perfect, but we can do it safely, more effectively, with less pain, certainly with less trauma to the patient, and with less need for anesthesia. Very few of these kids now need to go to a hospital and be put under anesthesia.

Dr. Ross: That is spot-on about the time: 0.5 Hz, 0.3 Hz, 5-mm spot, no cooling. Barbaric. You really could not treat anybody who had the slightest bit of pigment because you would get crusting. I look back at those times as dark days. What brought us into this modern age was the cooling—which meant you could use higher fluences—along with the larger spots and having other devices such as intense pulse light, 532 nm, and 595 nm. There was also the expanding array of applications, including rosacea, telangiectasia, and poikiloderma. Port wine stains started the ball rolling, but that is such a small fraction of what we see now. We can treat anything that is red, even discoid red lupus lesions and crest lesions, and of course, the cosmetic indications on a numerical basis far exceed the medical ones.

Dr. Geronemus: The newer devices have post-cooling as well. For the pediatric patient, even for the adult patient, this makes a huge difference. Not only are we cooling with a dynamic cooling spray before each laser pulse, but we are cooling after each laser pulse as well. Initially, there was a concern that this may inhibit or mitigate the response, but it does not, and it really does diminish the discomfort quite dramatically.

1. Jeon H, Bernstein LJ, Belkin DA, Ghalili S, Geronemus RG. Pulsed Dye Laser Treatment of Port-Wine Stains in Infancy Without the Need for General Anesthesia. JAMA Dermatol. 2019 Apr 1;155(4):435-441. doi: 10.1001/jamadermatol.2018.5249. Erratum in: JAMA Dermatol. 2019;155(4):504. doi: 10.1001/jamadermatol.2019.0710.