Unwanted/Excess Hair Removal Via the Diode Laser System

Hair Anatomy and Development
 Hair is composed of keratinous fibers that grow from epithelial follicles over the entire skin surface except in certain areas such as the palms of the hands and the soles of the feet. A person's total endowment of follicles is determined during his or her embryonic development. No new follicles are produced after birth.

Hair can be classified into two major types. Terminal hairs are thick, pigmented with melanin, and long. They are normally found on the scalp, the eyebrows, the underarms, and the genital areas as well as on the arms, chest, face, legs, and back. Vellus hairs are small in diameter, short, and non-pigmented.

The hair grows from a bulb, which consists of the dermal papilla and the hair matrix. The papilla is composed of highly vascularized connective tissue and provides nutrients for the rapidly dividing cells of the matrix. During active growth, the cells of the matrix divide every 23-72 hours, migrating upward to become keratinized, hardened, and tightly packed into layers that become the hair shaft.

Traditionally, it has been assumed that the papilla in the hair bulb directed cycling and hair regeneration, but recent experiments suggest that a "bulge" of cells in the follicular epithelium (near the attachment point of the arrector pili muscle) plays an important role as well. Consequently, the two primary targets for permanent hair destruction appear to be the regions of the bulge and the papilla. The bulge is approximately 1.5 mm below the epidermis, while the papilla is deep in the dermis (typically 3-7 mm from the surface of the skin).

Hair grows in recurring cycles. The phase of active hair growth is called anagen. During anagen the hair contains an abundance of melanin. A phase of regression is called catagen, during which cell division ceases and the lower part of the follicle starts to be reabsorbed. The final phase is a resting phase called telogen, during which the old hair falls out in preparation for development of a new hair. During telogen there is little or no melanin in the follicle.

The duration of the anagen phase is quite variable and can last up to 5-7 years in scalp follicles. The catagen phase has a relatively constant duration, generally lasting about three weeks. The telogen phase typically lasts on the order of three months.

Each follicle in human skin maintains an independent growth rhythm from the other follicles. At any given time, the majority of hair follicles (80-85%) are at some point in anagen. The remaining follicles are either in the catagen phase (2%) or the telogen phase (10-15%). The average scalp hair grows at a rate of approximately 37 mm per month while hairs at other anatomic sites generally grow more slowly.

Just as the anatomic target for laser hair removal is the bulge and papilla, the temporal target is the anagen phase. Hairs in the resting or regression phases appear to be less susceptible to the effects of laser light. However, after initial treatment with the LightSheerTM Diode System, the hairs that regrow appear to be synchronized in the early anagen phase, where they are most vulnerable to treatment with laser light. For this reason, any necessary retreatment should be performed not at a fixed interval but rather as soon as possible after the hairs begin to regrow.
Causes of Excessive Hair
 There are two major types of excessive hair disorders. Hypertrichosis is an increase in the amount of hair in regions that do not respond to male hormones (androgens) while hirsutism is an increased amount of hair in androgen-dependent areas only. Hypertrichosis may be localized to a single area or generalized over large areas of the body and it can occur in both men and women. In hirsutism, women develop male hair patterns, such as facial hair. In general, fine vellus hairs become course terminal hairs in women who have the condition.

The development of unwanted, excess hair may be genetically determined as a normal familial trait. It may also occur in association with one of several inherited disorders, or it may occur as a complication of tumors of the ovaries or adrenal glands. Finally, certain medications, especially androgens, can cause development of unwanted hair.

Table 1.

Causes of Hirsutism and Hypertrichosis

Virilizing Tumors
Adrenal Gland
Adrenal carcinoma
Adrenal virilizing adenoma
Congenital adrenal hyperplasia
Ovary
Arrhrenoblastoma
Granulosa-stromal tumor
Lipoid cell tumor
Hilus cell tumor
Syndromes
Polycystic ovary
Hereditary - normal variant
Idiopathic hirsutism
Endocrine disorders
Cushing's disease
Medications
Androgens
Birth control pills
Minoxidil
Phenytoin
Penicillamine
Diazoxide
Cyclosporine
Corticosteroids
Malnutrition
Orphyria
Anorexia nervosa
Hypothyroidism (children)
Dermatomyositis



Traditional Treatments to Remove Unwanted Hair
 A variety of techniques have been used traditionally to remove unwanted hair. The most common include:

While all of these methods are effective over the short term, they are in turn inconvenient, messy, painful, or associated with significant risks such as infection or scarring. And of all of them, only the electricity-based methods have been shown to provide permanent hair removal.

The two types of electricity-based removal of hair are called electrolysis and electrothermolysis (or thermolysis for short). In electrolysis, a weak DC current is passed into the deep portion of follicles between two electrodes. The procedure works by generating hydrogen gas and reactive hydrogen ions that chemically destroy the adjacent hair follicle. In electrothermolysis, high frequency alternating current at low voltage and low current is used to generate heat and thermally destroy hair follicles. Electrolysis is safe, less painful, and less likely to cause scarring than electrothermolysis, but the tradeoff is very slow treatment times, especially when large areas are epilated. Devices that blend both electrolysis and electrothermolysis are common.

 Theoretical Basis and Practical Application of Laser Hair Removal

 The LightSheer Laser The LightSheerTM Diode System is designed to remove unwanted hair through selective photothermolysis. The process involves local selective absorption of an intense light pulse at wavelengths that are absorbed by the desired targets (hair follicles) but not by the surrounding tissue. Like electrothermolysis, photothermolysis destroys hair follicles through thermal damage. Unlike electrothermolysis, the skin is not breached (which reduces the risk of infection), and many follicles can be treated simultaneously.

The theory of selective photothermolysis predicts that thermal injury can be confined to a given target if it is treated with the proper wavelength of light, proper pulse energy, and a pulse duration that is equal to or less than the thermal relaxation time (TRT) of the target tissue. In human skin, 800 nm laser energy is selectively absorbed by melanin. Melanin is found interspersed between the matrix cells in the hair bulb and is also transferred to the structural elements of the hair shaft during its development. The amount of melanin in the follicular epithelium and the papillae is sufficient to act as a chromophore for light absorption in the follicle. The energy is selectively absorbed by the melanin in the hair shaft as well as the surrounding follicle, causing thermal destruction of several key anatomic sites. The hair's growth is significantly impeded, or eliminated. Damage to adjacent tissues is minimized by using pulses shorter than the TRT of the follicle.

A second way to increase the penetration depth of light is by using light from a laser having a large spot size. This phenomenon is apparently the result of the greater internal reflection (scattering) that occurs with wider diameter beams of light. Compression of the skin with a contact delivery system can also increase light transmission in the dermis.

One factor limiting the specificity of the LightSheerTM Diode laser energy to hair follicles is the presence of melanin in the epidermis. Thus, delivery of laser light that targets melanin can also result in epidermal injury characterized by postoperative crusting or irregularities in pigmentation.

In the LightSheerTM Diode System, the ChillTipTM cooling lens provides thermal protection for the epidermis, allowing higher doses of laser energy to safely and effectively target unwanted hair follicles. The handpiece consists of an actively cooled sapphire lens that has three purposes. First, it cools the epidermis to help prevent thermal damage. Second, it focuses the laser light to maximize dose penetration to deep hair follicles. Finally, its convex shape allows compression of the skin during treatment which temporarily collapses the blood vessels, lies down hairs, brings the root of the hair closer to the laser energy, and increases transmission through dermal collagen by as much as 40%.

 Summary of Clinical Results Using the LightSheerTM Diode System
 The LightSheerTM Diode Laser System has been studied for epilation and treatment of leg veins at the Massachusetts General Hospital and the Laser and Skin Surgery Center of New York. Large test sites on the back or thighs of 58 consecutive patients with skin types I-V (fair to dark-skinned) and any hair color, were shaved and treated with a range of 15-40 J/cm2 fluence using the LightSheerTM Diode System. The key results were:
About 70% of patients with black, brown, auburn, or red hair had long-term hair reduction, compared to only about 10% of patients with blond hair. The degree of long-term hair reduction was determined by the energy fluence. The higher the energy delivered to the hair follicles, the greater the degree of long-term reduction.

No serious complications occurred during the study. The most common side effect (occurring in about one in six patients) was
transient hyper- or hypopigmentation that resolved between one and six months after treatment. Other side effects included pain, erythema, edema, and blistering. These side effects generally resolved within a few days of treatment. No scarring was observed during the studies.

Although comprehensive long-term results with the LightSheerTM Diode System have not yet been compiled, clinical trials are ongoing to evaluate the long-term effects of the treatment and to optimize the procedure.

The LightSheerTM Diode System has also been used for the treatment of superficial leg veins. In one clinical study of this use, twenty-four patients with superficial varicosities on the upper or lower legs were treated with a range of fluences of 15-40 J/cm2. Treatment exposures were delivered with gentle pressure to allow skin surface cooling, but not compression of the veins being treated. The primary measure of efficacy was visual grading by the investigators of vessel clearance. At a fluence of 40 J/cm2, vessel clearance continued to improve for at least three months after a single treatment. By three months, 88% exhibited some improvement in the treated leg veins, and 44% were graded with clearance. With multiple treatments, vessel clearance increased significantly. After three treatments, 83% of subjects exhibited 50% clearance; 40% had nearly completed clearance, and 12% had clinically completed clearance. Three subjects showed no improvement.

Patient Selection
 Patient selection is a key aspect of the effective use of the LightSheerTM Diode System. Hair color and skin type are the two most important factors in predicting success of treatment. Temporary hair loss almost always occurs regardless of hair color. Long-term hair loss, however, is correlated with hair color. Black or brown hair, indicating a high concentration of melanin in the follicles, is ideal. Blond, white, or grey hair is treated less effectively. Hair loss in these patients can be maintained, if desired, by retreating when hair starts to regrow (anagen phase) in the treated area, which occurs at approximately three-month intervals.

Using the Fitzpatrick classification system, skin type can be characterized using the following system based on pigmentation:

Skin Type Characteristic


In the experience of the investigators who initially tested the LightSheerTM Diode System, people with skin Types I and II are most easily treated. People with skin Types III, IV, and V may require pre treatment with sunscreen and bleaching creams to reduce the amount of melanin in the epidermis. People with skin Type VI are of high risk for skin damage with treatment and are generally not treated.

Of course, before treatment a full history should be taken to identify possible endocrine disorders (related to hirsutism), allergies, current medications, local infections in areas to be treated, previous scarring, etc.

There are no known contraindications to hair removal using the LightSheerTM Diode System. Patients who have had prior problems with laser therapy, however, should be carefully screened before treatment. Additionally, persons known to form skin keloids may be more prone to scarring after any skin trauma, including laser treatment.

Caution is advised in treating patients with any of the following conditions:

 Pretreatment Instructions
 Patients who are tanned or who have skin Types III, IV, or V are advised to avoid tanning for 2-3 months prior to therapy and use a sunscreen (SPF 15-30) on exposed areas for 4-6 weeks before treatment. In addition, some physicians recommend pretreatment with a bleaching cream; 4% hydroquinone twice daily for at least six weeks prior to treatment. The efficacy of this bleaching cream can be enhanced by combining its use with topical application of retinoic acid cream 0.025% twice daily for four weeks. Use of the hydroquinone and retinoic acid should be stopped for two weeks prior to treatment.

All patients should be advised to avoid waxing, plucking, depilatory creams, or electrolysis for at least six weeks prior to treatment. They may continue to shave for up to two weeks prior to the test treatment. For assessment and documentation photos, full hair growth is required. After the initial assessment, the patient may continue to shave throughout treatment. In fact, a clean shave before treatment may decrease the odor caused by laser destruction of hair visible above the surface of the skin and will reduce the risk of inadvertent epidermal injury caused by heat conducted from unshaved hairs.

Postoperative Care
In most cases, treatment will result in a mild sunburn-like sensation that typically disappears without treatment in 2-3 hours. Some mild redness and minor swelling may persist for 2-3 days following treatment, but dressings are usually not required. Following treatment, the treated site should be washed gently twice a day with soap and water. Any crusted areas should be treated twice daily with the application of a topical antibiotic ointment. Sunlight should always be avoided after treatment, and sunscreens should be applied daily.

  1. Avoid bathing or washing with hot water.
  2. Keep the area moisterized. (Ex: Moisturel, Lubriderm, Cortaid).
  3. Avoid the sun and use sunscreen daily.
  4. Continue to avoid irritants on face, (Ex: Retin-A, Afirm, Benzoyl Peroxide, glycolic acid, astringents) for at least 7 to 10 days.
  5. Please feel free to call the office if youi have any questions.

Retreatment
 If hair starts to regrow in the treated area, it is generally best to perform retreatments. This regrowth or early anagen growth phase typically occurs between one and six months following the initial treatment. There is no known advantage to retreatment prior to hair regrowth.

Questions and Answers About Laser Hair Removal
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