Selective Photothermolysis for Skin Conditions

What is Selective Photothermolysis and When is it Used?

Physicians in the operating room performing surgery
What is selective photothermolysis, how does it work, and when is it used?. Credit: Caiaimage/Martin Barraud / Getty Images

Selective Photothermolysis

Selective photothermolysis (fō'tō-thĕrm-ol'i-sis) is a precise microsurgery technique used to target tissue in a specific area. It matches the specific wavelength of light and heats the tissue and destroys it with a laser without affecting or damaging surrounding tissue. The targeted cells are destroyed by the absorption of light and transfer of energy.

While the term "selective photothermolysis" may sound like a high school physics concept you never understood, the term is really quite easy to understand when broken down.

Selective means just that. The procedure "selects" an abnormal area to treat in contrast to surrounding normal tissue. Photo, refers to light. The laser sends out light. Thermo refers to heat. So the light now creates heat. Finally lysis refers to destruction. All in all, selective photothermolysis refers to using light to heat and destroy tissue in a selective area of the body.

How Does Selective Photothermolysis Work?

Decreasing a lasers pulse time allows surgeons to provide short bursts of energy to the tissue. The pulse limits peripheral damage yet creates enough power to affect the targeted area.

The target of the laser is determined by its color. For instance, when selective photothermolysis is used in laser tattoo removal, the laser targets specific colors. Different lasers, or different settings on the same laser, are then used to break up different colors of the ink of the tattoo.

Conditions for Which Selective Photothermolysis May be Used

Selective photothermolysis was first developed for the process of laser hair removal but has since been used in the treatment of the following conditions:

  • Laser hair removal (photoepilation.)
  • Tattoo removal.
  • Port wine stains - A port wine stain may occur as an isolated condition, or may be part of a condition such as Sturge-Weber syndrome or Klippel-Trenaunay-Weber syndrome. Port wine stains are pink to reddish patches of skin ("birth marks") which occur in 0.3 to 0.5 percent of the population. In addition to being disturbing cosmetically,  these lesions can darken as people age, sometimes developing into pyogenic granulomas.
  • Warts.
  • Spider veins.
  • Melasma.
  • Photoaging of the skin (aging changes.)

How Selective Photothermolysis Works in These Conditions

The light energy that is emitted by the laser is absorbed by the molecules responsible for its color, and precisely targets and destroys molecules responsible for the color.

For hair removal, the molecules would be melanin. For port wine stains, the molecules would be hemoglobin. With port-wine stains, the blood inside the blood vessels is heated due to the selective absorption of the laser energy.

The laser’s wavelength and the length of its pulse will determine the effectiveness of treatment.

You may wish to learn more about the different types of lasers and how they work.

When Does Selective Photothermolysis Work Best?

Selective photothermolysis is the reason why a pale-skinned patient with a black tattoo will achieve better and fastest results.

The laser breaks down the dark ink leaving the pale skin around it intact. Black is the easiest color to remove, followed by red, and then green and blue. It also explains why ink colors which are closer to skin colors, such as brown, yellow, or pink, are more challenging to remove.

Goodbye to Tattoos

If you are considering having a tattoo removed, it can be helpful to learn some of the history and basics about tattoo removal. Unlike the sometimes impulsive decision, followed by a few hour procedure (or less) process of getting a tattoo, removing a tattoo requires a commitment to time and often multiple visits.

From the length of time you will need to wait between treatments, to learning about which type of tattoos are the easiest to remove, and even a discussion about how painful these procedures may be, check out these questions and answers about tattoo removal.

Possible Side Effects and Complications

The most common "complication" of selective photothermolysis is inability to resolve the pigmented skin lesion completely. The procedure works best when there is a significant contrast between the color of the skin and normal surrounding skin. The procedure is also limited to what can be accomplished by the laser surgery. For example, selective photothermolysis may resolve some skin changes secondary to aging or treat some problems related to inflammatory acne, but certainly not all.

As with any laser technique, there can be damage (burns) to surrounding normal tissues in some cases.

Bottom Line on Selective Photothermolysis

Procedures such as selective photothermolysis provide another method for people to treat skin conditions ranging from unwanted tattoos, to congenital port wine stains, to changes related to inflammatory acne. It's likely that with current knowledge, procedures such as this will continue to improve in ways which helps physicians treat unwanted skin coloring without harming nearby tissues.

Sources:

Baumler, W. Laser Treatment of Tattoos: Basic Principles. Current Problems in Dermatology. 2017. 52:94-104.

Borges, J., Manela-Azulay, M., and T. Cuzzi. Photoaging and the Clinical Utility of Fractional Laser. Clinical Cosmetology and Investigational Dermatolgoy. 2016. 9:107-14.

Brightman, L., Geronemus, R., and K. Reddy. Laser Treatment of Port-Wine Stains. Clinical Cosmetology and Investigational Dermatology. 2015. 8:27-33.

Paithankar, ., Sakamoto, F., Farinelli, W. et al. Acne Treatment Based on Selective Photothermolysis of Sebaceous Follicles with Topically Delivered Light-Absorbing Gold Microparticles. The Journal of Investigational Dermatology. 2015. 135(7):1727-34.

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