Discussion of target tissue in laser hair removal treatment

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Home >> Aspects of Laser treatment >> Target tissue and laser hair removal
Target tissue and laser hair removal
Why laser hair removal is preferred
Laser is used in various medical procedures. Laser treatment is preferred because it is a long-lasting method of hair removal, unlike shaving or threading. Laser treatment is used to remove facial hair and age spots. The principle is simple: laser energy is transformed into heat, which disables the hair follicles leaving the surrounding skin unchanged. This instantly arrests hair growth.

The use of laser in removing unwanted hair is nothing new. Laser was first used for hair removal on an experimental basis some 20 years ago and became commercially available in the mid 1990s. In addition to laser, some epilators use a xenon flash lamp which emits full-spectrum intense pulse light (IPL).

How it works
Laser works by focusing on certain areas just below the skin, without heating the rest of it. Energy emitted by laser is absorbed by dark objects - the chromophores - that can be either natural or artificial.

The patient undergoing hair removal laser surgery wears a safety eyegear to protect the eyes. The laser beam is flashed from a small hand-held piece. The discomfort experienced is generally quite endurable, though it varies according to the patient's constitution and. Indeed some might even need to be administered local anesthesia.

Laser wavelength required to achieve results
The laser wavelengths used in hair removal laser surgery include visible light to near-infrared radiation. Laser wavelengths are determined by the lasing medium that is used to create them and are measured in nanometers (nm).

Below are some of the wavelengths that are employed in hair removal laser surgery:
  • Argon: 488 or 514.5 nm
  • Ruby: 694 nm
  • Alexandrite: 755 nm
  • Pulsed diode array: 810 nm
  • Nd:YAG: 1064 nm
Pulsewidths are crucial in laser treatment. It has been observed that longer pulsewidths are the safest for dark skins.

It is also known that the spot size, or the width of the laser beam, can make all the difference. Lasers generally have a round spot about the size of a little finger. The width of an ideal beam should be about four times as wide as the target is deep.

Energy level, also known as fluence, is another important aspect of hair removal laser surgery. It is measured in joules per square centimeter (J/cm2).

Besides these, repetition time is also taken into account. If two or more pulses are shot at the same target with a certain delay between the pulses it helps in heating up the problem area.

How laser works on target tissue
Hair removal laser surgery works by causing localized damage by heating dark target matter (the area that causes hair growth) while leaving the rest of the skin untouched. It works on the principle of selective photothermolysis: it is that light is naturally absorbed by dark materials. The skin's dark target area (the chromophore) is of three kinds - carbon, hemoglobin and melanin, and the laser beam targets one of these.

Carbon is introduced in the hair follicle by rubbing a carbon-based lotion into the skin. This causes a shock wave which is capable of mechanically damaging nearby cells when irradiated by a Q-switched Nd:YAG laser. This method has been abandoned because it is incapable of achieving permanent hair removal.

Hemoglobin occurs naturally in blood and is responsible for tis red color. It is not a primary target for laser hair remova and gets wavelengths from argons, rubies, alexandrites and diodes.

Melanin occurs naturally in the skin and gives the skin and hair their colors. It is the main chromophore used in all laser hair removal treatment.

Number of sessions needed
How many sessions of hair removal laser surgery a patient needs depends on several factors. Localization of the area treated and gender are important, as also the fact that certain areas of the body require longer treatment than others. Generally, though, three to six laser surgery sessions are considered good enough.

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