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Laser hair removal

Epilation performed by laser was performed experimentally for about 20 years before it became commercially available in the mid 1990’s. Laser and light-based methods are sometimes called phototricholysis or photoepilation.

In addition to lasers, some light-based epilators use a xenon flashlamp which emits full-spectrum intense pulsed light (IPL). Treatment with this device is sometimes popularly referred to as laser hair removal, though the device is not a laser per se.

The primary principle behind laser hair removal is selective photothermolysis. Lasers can cause localized damage by selectively heating dark target matter in the area that causes hair growth while not heating the rest of the skin. Light is absorbed by dark objects, so laser energy can be absorbed by dark material in the skin (but with much more speed and intensity). This dark target matter, or chromophore, can be naturally-occurring or artificially introduced.

Hair removal lasers selectively target one of three chromophores:

  • Carbon, which is introduced into the hair follicle by rubbing a carbon-based lotion into the skin following waxing (this lotion is an “exogenous chromophore”). When irradiated by a Q-switched Nd:YAG laser, the carbon causes a shock wave capable of mechanically damaging nearby cells. This method has been abandoned since it does not cause permanent loss. (It has been replaced with the long-pulsed Nd:YAG laser which targets endogenous melanin in the follicle.)
  • Hemoglobin, which occurs naturally in blood (it gives blood its red colour). It preferentially absorbs wavelengths from argons, and to a lesser extent from rubies, alexandrites, and diodes. It minimally absorbs the Nd:YAG laser wavelength. Hemoglobin is not a primary target for laser hair removal.
  • Melanin is considered the primary chromophore for all hair removal lasers currently on the market. Melanin occurs naturally in the skin (it gives skin and hair its colour). There are two types of melanin in hair: eumelanin (which gives hair brown or black colour) and pheomelanin (which gives hair blonde or red colour). Because of the selective absorption of photons of laser light, only black or brown hair can be removed. However newer laser technology shows promising developments that may be able to effectively treat other colours of hair.

Any laser light beam intended for topical use can only penetrate skin tissue two millimetres deep. As such, there has been great controversy surrounding the laser industry claims to what most people think of when they hear the word “permanent”. (see next section)

The dermal papilla is the only appropiate target of destruction, as it it is the only substructure of the hair shaft which can reproduce a new root system, and therefore a new hair shaft. The dermal papilla is located at a depth of 7-8 millimetres for coarse hair.

If you are interested in laser hair removal, T-Vox maintains a list of specialists who are known to work well with transgender people.

Myth versus fact: permanence?

This is a key area in the use of laser hair removal in treatment of trans women.

Earlier lasers were not necessarilly perminant, and this has given rise to some myths that laser hair removal is not an ideal form of hair removal. However advances in laser technology have now falsified this statement, and new generation lasers are more than capable of perminantly removing both facial and body hair.

It should be noted though that the laser will not remove or destroy dormant hair follicles. Any rise in testosterone levels, such as during the period off hormones prior to any major surgery may prompt these dormant follicles to begin growing. Once activated, a hair follicle on the facial region will most likely require a further course of hair removal to ensure its removal. This is because once activated by testosterone the follicle does not need testosterone to remain present in the body to continue growing.

Laser parameters that affect results

Several wavelengths of laser energy have been used for hair removal, from visible light to near-infrared radiation. These lasers are usually defined by the lasing medium used to create the wavelength (measured in nanometres (nm)):

  • Argon: 488 or 514.5 nm
  • Ruby: 694 nm
  • Alexandrite: 755 nm
  • Pulsed diode array: 810 nm
  • Nd:YAG: 1064 nm

Pulsewidth is an important consideration. It has been observed in some published studies that longer pulsewidths are safer in darker skin.

Wavelength is a critical factor. Longer wavelengths are safer in darker skin.

Spot size, or the width of the laser beam, affects treatment. Theoretically, the width of the ideal beam is about four times as wide as the target is deep. Most lasers have a round spot about the size of your little finger (8-10 mm).

Fluence or energy level is another important consideration. Fluence is measured in joules per square centimetre (J/cm2).

Repetition rate is believed to have a cumulative effect, based on the concept of thermal relaxation time. Shooting two or three pulses at the same target with a specific delay between pulses can cause a slight improvement in the heating of an area.

Epidermal cooling has been determined to allow higher fluences and reduce pain and side effects, especially in darker skin. Four types of cooling have been developed:

  • Clear gel: usually chilled
  • Contact cooling: through a window cooled by circulating water
  • Cryogen spray: immediately before/after the laser pulse
  • Air cooling: forced cold air at -34 degrees C (Zimmer Cryo 5 unit)

Multiple treatments have been shown in numerous studies to be more effective for long-term reduction of hair. Current parameters suggest a series of treatments spaced at 1 month for the face, 2 months for the chest and 3 months for the legs. Part of this may be because not all hairs are in the growing phase in any one area at any one time.

Laser energy also gets less effective the deeper into the skin it must travel. Think of it like putting your hand over a flashlight. A little light penetrates the thinner skin (the reddish glow), but can’t penetrate the thicker areas. Light that enters the skin is either absorbed or scattered and reflected back out of your hand. When this happens to a laser beam, this scattering is called attenuation. The more tissue light has to travel through, the more attenuation will occur. That means at deeper levels, less energy reaches the target.

Other Uses

Hair removal lasers are effective treatment for pseudofolliculitis barbae (commonly called ingrown hairs or “shaving bumps”). For darker skin patients with black hair, the long-pulsed Nd:YAG laser with a cooling tip can be safe and effective when used by an experienced practitioner.

They have recently been reported as helpful treatment for pilonidal cysts, since they eliminate the ingrown hairs that produce the troublesome foreign body reactions in this congenital malady.

See also

External links

Article created for T-Vox by Jennifer Kirk, based on a variety of sources.