Introduction to Lasers

What are lasers?

“Laser” is an acronym for light amplification by stimulated emission of radiation. A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. Long story short, lasers work by emitting light.

What are the different types of lasers?

There are different types of lasers based on the kind of light that they emit. The physics behind this is due to the natural occurrence of crystals in the environment. Crystals release light after relaxing from activated states. Different lasers have different crystals that can release a very narrow band of light that is specific to that crystal, and this light can selectively target different parts of the skin.

How do lasers work on skin?

To understand how lasers work on the skin, one must realize that not all light is the same. There is a wide spectrum of light, and that light comes in different sizes called wavelengths. For example, the light emitted by the sun has a specific wavelength. The colors that you see – blue, red, yellow, these have different wavelengths. The same goes for ultraviolet and infrared light.

There are components on the skin that absorb different wavelengths of light with different affinities. For example, blood vessels will be able to absorb specific wavelengths of light, while it will not absorb other wavelengths. When light hits the target on the skin (e.g. blood vessels), the light is absorbed preferentially by that target and not by the surrounding tissue so that that target can be effectively heat-damaged without damaging the surrounding area. Therefore, depending on the skin condition that you have, your dermatologist will choose a specific type of laser that emits a specific wavelength of light, because your condition responds to a specific band of light. As you recall, different types of lasers have different crystals emitting specific wavelengths of light. Different skin diseases respond to different wavelengths, which is why different lasers treat different skin conditions.

What are the skin conditions lasers can be used for?

Here are some examples of laser targets on the skin, specific skin conditions and the lasers used to address them:

Target: Blood vessels

Conditions: Blood vessels that show up on the face (also called telangiectasia, due to chronic sun damage or rosacea), spider veins, warts (laser targets the blood vessels in the wart) and hemangiomas (non-cancerous growth of blood vessels).

Lasers: Pulsed-Dye laser, Nd:YAG laser

Explanation: These lasers target hemoglobin in the blood (what makes our blood red). By targeting hemoglobin, blood vessels can be destroyed.

Target: Hair

Conditions: For hair removal

Lasers: Alexandrite laser, Nd:YAG laser, Diode laser

Explanation: The lasers target the skin pigment called melanin. Darker hair has more pigment, so it absorbs the laser energy better and is destroyed more easily compared to lighter hair. It is good to be aware that lasers may not permanently remove hairs, but are able to reduce their size so that they grow much slower and become less visible.

Target: Skin pigment

Conditions: Lentigo or sunspots, melasma (non-cancerous pigmented skin conditions)

Lasers: Nd:YAG laser

Explanation: Similar to #2, lasers target the melanin pigment in the skin to destroy pigmented lesions. However, not all pigmented lesions should be removed by lasers. For example, pigment lasers should not be used to treat skin cancers like melanoma or a benign lesion that is not only due to a pigment change like seborrheic keratosis. This is why it is of the utmost importance to have a board-certified dermatologist assess your skin first prior to laser procedures.

Target: Water

Conditions: Acne scars and Wrinkles (fractional laser); Warts, Syringoma, Sebaceous hyperplasia, Fibromas (non-fractional laser)

Lasers: Carbon dioxide laser, Er:YAG laser (both can be fractional or non-fractional)

Explanation: Water makes up most of our skin. These lasers can effectively remove benign raised lesions (non-fractional lasers) and improve acne scars and wrinkles (fractional lasers). By targeting water, these lasers create zones of microinjury that stimulate the production of collagen. This production of collagen can replenish lost collagen, leading to an improvement in acne scars or wrinkles. This is also called skin rejuvenation or skin resurfacing.

Lasers can be very effective when used at the right settings, but like any skin treatment, it must be personalized to the patient’s skin type and accompanying conditions. For example, it is crucial to take skin pigment level into account when choosing the right laser treatment. As I mentioned above, darker skin has more pigment and may absorb energy more than lighter skin, so the former has a greater risk for skin darkening (known as hyperpigmentation), skin lightening (known as hypopigmentation), blistering, and scarring. It is also very important for patients to understand the different advantages and disadvantages of each laser treatment, particularly the expected downtime or side effects. Keep yourself informed and don’t be afraid to ask questions from your board-certified dermatologist.

Skincerely yours,

Dr. Mara Evangelista-Huber

Scroll to Top