LASER hair removal : All the facts you should know
Laser hair removal is one of the relativily recent ways for getting rid of unwanted hair and it is now used by millions of women all over the world . lots of false data have been said about laser that’s why i chosed to write this article to help you understand the truth about laser
Each of the letters laser actually stands for a word
What’s the difference between laser and visible light?
Laser light has special qualities:
• it is of a single wavelength
• the light beams travel in parallel
• the light beam waves are in phase
• it can be made very intense or not intense at all • it can be focused to a tiny spot
What are the physics of Laser?
•The light is produced within an optical cavity containing a medium, which may be a gas (e.g. argon, krypton, Co2), liquid (e.g. dye) or solid (e.g. ruby, Nd:Yag, alexandrite).
• Each medium produces a specific wavelength of light, which may be within the visible spectrum (violet 400 through to red 700nm) or infrared spectrum (more than 700 nm).
• The aim is to destroy the target cells and not to harm the surrounding tissue. Short pulses reduce the amount that the damaged cells heat up, thereby reducing thermal injury that could result in scarring.
• The absorption coefficient is a measure of the degree of absorption by the chromophores at a particular wavelength. Because the laser is monochromatic and because it has a very narrow bandwidth, it permits selective targeting of chromophores in the tissue for treatment.
• Vascular skin lesions contain oxygenated haemoglobin, which strongly absorbs visible light at 418, 542 and 577 nm, whereas pigmented skin lesions contain melanin, which has a broad range of absorption in the visible and infrared wavebands. Infrared lasers are broadly destructive because they are absorbed by water in and between skin cell. (these are composed of 70-90% water).
What are the common types of laser and their wave lengths?
• Excimer (XeCl) 308
• Alex 755
• Diode 810
• Nd:YAG 1064
• Ho:YAG 2100
• Erbium:YAG 2940
• Co2 10600
Laser hair removal was performed experimentally for about 20 years before it became commercially available in the mid 1990s. The efficacy of laser hair removal is now generally accepted in the dermatology community, and laser hair removal is widely practiced in clinics, and even in homes use devices designed and priced for consumer self-treatment.
What’s the mechanism of action?
The primary principle behind laser hair removal is selective photothermolysis , the matching of a specific wavelength of light and pulse duration to obtain optimal effect on a targeted tissue with minimal effect on surrounding tissue. Laser can cause localized damage by selectively heating of dark target matter, melanin, in the area that causes hair growth, the follicle, while not heating the rest of the skin.
Melanin is considered the primary chromophore for all hair removal lasers currently on the market. Melanin occurs naturally in the skin, and gives skin and hair their color. There are two types of melanin in hair. Eumelanin gives hair brown or black color, while pheomelanin gives hair blonde or red color. Because of the selective absorption of photons of laser light, only black or brown hair can be removed. Laser works best with dark coarse hair. Light skin and dark hair are an ideal combination, being most effective and producing the best results, but new lasers( e,g NDYAG) are now able to target dark black hair with some success in patients with dark skin.
Hair removal lasers have been in use since 1997 and have been approved for “permanent hair reduction” in the United States by the Food and Drug Administration (FDA).
Under the FDA’s definition, “permanent” hair reduction is the long-term, stable reduction in the number of hairs regrowing after a treatment regime. Many patients experience complete regrowth of hair on their treated areas in the years following their last treatment. This means that although laser treatments with these devices will permanently reduce the total number of body hairs, they will not result in a permanent removal of all hair. That’s why touch up sessions is needed.
Laser hair removal has become popular because of its speed and efficacy, although some of the efficacy is dependent upon the skill and experience of the laser operator, and the choice and availability of different laser technologies used for the procedure. Some will need touch-up treatments, especially on large areas, after the initial set of 6-8 treatments. .
Several wavelengths of laser energy have been used for hair removal, from visible light to near-infrared radiation. These lasers are characterized by their wavelength, measured in nanometers (nm))
Argon: 488 nm (Turquoise/Cyan) or 514.5 nm (Cyan) (no longer used for hair removal)
Ruby laser: 694.3 nm (Deep Red) (no longer used for hair removal; only safe for patients with very pale skin)
Alexandrite: 755 nm (Near-Infrared) (most effective on pale skin and not safe on darker skin at effective settings)
Nd:YAG laser: 1064 nm (Near-Infrared) (made for treating darker skin types, though effective on all skin types)
Longer pulse widths may be safer for darker skin, but shorter pulse widths are more effective in disabling hair follicles.
Pulse width (or duration) is an important consideration.
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. Hair removal lasers have a spot size about the size of a fingertip (8-18mm). Larger spot sizes help laser light penetrate deeper and make treatments faster and more effective
Fluence or energy level is another important consideration. Fluence is measured in joules per square centimeter (J/cm²). It’s important to get treated at high enough settings to heat up the follicles enough to disable them from producing hair.
Epidermal cooling has been determined to allow higher fluences and reduce pain and side effects, especially in darker skin.
What’s the average number of sessions?
Multiple treatments depending on the type of hair and skin color have been shown to provide long-term reduction of hair. Most patients need a minimum of seven treatments.
Current parameters differ from device to device but manufacturers and clinicians generally recommend waiting from three to eight weeks depending on the area being treated. The number of sessions depends on various parameters, including the area of the body being treated, skin color, coarseness of hair, reason for hirsutism, and gender.
Coarse dark hair on light skin is easiest to treat.
Certain areas (notably men’s faces) may require considerably more treatments to achieve desired results. Hair grows in several phases (anagen, telogen, catagen) and a laser can only affect the currently active growing hair follicles (anagen) which is around 10% of the total hair in any treatment area .
Hence, several sessions are needed to kill hair in all phases of growth. This problem is countered by spacing appointments sufficiently so that inactive follicles will start to grow again. Laser does not work well on light-colored hair, red hair, grey hair, white hair, as well as fine hair of any color, such as vellus. 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.
What should you expect from laser?
Although laser hair removal effectively slows hair growth, it doesn’t guarantee permanent hair removal. It typically takes several laser hair removal treatments to provide an extended hair-free period. Periodic maintenance treatments might be needed as well
What’s the Interval between sessions?
Usually treatments are spaced three to eight weeks apart depending on the body area and the hair cycle length for that area. The face usually requires more frequent treatments two to three weeks apart, whereas legs require less frequent treatments and patients should be advised to wait at least six weeks. Typically the shedding of the treated hairs takes about two to three weeks. These hairs should be allowed to fall out on their own and should not be manipulated by the patient
What are the possible side effects and risks?
Some normal side effects may occur after laser hair removal treatments, including itching, redness, and swelling around the treatment area. These side effects rarely last more than two days. The most common serious side effect is change in skin pigment.
Some level of pain should also be expected during treatments. Numbing creams are available at most clinics. Typically, the cream should be applied about 30 minutes before the procedure. Icing the area after the treatment helps relieve the side effects faster.
Unwanted side effects such as hypo- or hyper-pigmentation or, in extreme cases, burning of the skin call for an adjustment in laser selection or settings. Risks include the chance of burning the skin or discoloration of the skin, hypopigmentation (white spots), flare of acne, swelling around the hair follicle, scab formation, purpura, and infection.
These risks can be reduced by treatment with an appropriate laser type used at appropriate settings for the individual’s skin type and treatment area
Some patients may show side effects from an allergy to either the hair removal gel used with certain laser types or to a numbing cream.
About the author:
Dr Randa Mohamed Saad
Masters degree in Dermatology, Venereollogy and Andrology- Faculty of medicine- Alexandria University.
Fellow of Duplin University, Irland.