Hair, Laser Removal

Article Author:
Tanvi Vaidya
Article Editor:
Dinesh Kumar D
Updated:
10/27/2018 12:31:41 PM
PubMed Link:
Hair, Laser Removal

Introduction

The demand for safe, long-lasting, and effective hair reduction for aesthetic as well as medical indications is on the rise. A variety of options for hair removal are available, such as epilation by plucking or waxing, depilation by shaving, chemical depilatories, electrolysis, eflornithine cream, and laser and intense pulsed light (IPL) systems. A variety of lasers and IPL systems are available and are the best option for long-term hair reduction. The mechanism of action of these systems is by targeting melanin in the hair shaft, follicular epithelium, and hair matrix by emitting light with wavelengths ranging from 600 to 1200 nanometers (nm), which is selectively absorbed by melanin.

Anatomy

Selective Photothermolysis

Lasers for skin treatment work on the theory of "selective photothermolysis." This term implies a site-specific, thermally mediated injury of microscopic tissue targets by the selective absorption of pulses of radiation by the targets and the chromophores. The natural or artificial chromophores absorb monochromatic or broadband electromagnetic radiation of specific wavelengths. The chromophore employed in laser hair reduction is melanin. Melanin absorbs light in the range of 690 to 1000 nm, and lasers in this range of wavelengths can be effectively used for hair reduction.

An Extended Theory of Selective Photothermolysis

Target absorption may not always be uniform. In these cases, the weakly absorbing parts may have to be destroyed by heat diffusion from the highly absorbing parts. This is the extended theory of selective photothermolysis. This principle is applied to laser photoablation. Melanin content is much higher in melanin-bearing structures like the hair shaft and matrix cells than in the hair follicle. Thus melanin captures energy from the laser and distributes it to the surrounding follicular structures. This results in the destruction of the hair matrix and hair bulge stem cells.

Indications

  1. Hirsutism and hypertrichosis
  2. Aesthetic purposes
  3. Medical indications like Pseudofolliculitis barbae, pilonidal sinus, and acne keloidalis nucha.

Contraindications

  1. Age less than 15 years
  2. Tendency for scarring and keloid formation
  3. Infection at the local site
  4. Superficial wounds in the procedure area

Equipment

Lasers for hair reduction include the following:

  1. Ruby LaserWavelength: 694 nmRed light is delivered through synthetic Ruby crystalsMore effective for lighter skin types with dark hairSkin types I-III*
  2. Alexandrite LaserWavelength: 755 nmGreater penetranceGood for lighter hairSkin types I-III
  3. Diode LaserWavelength: 810 nmPenetrates deeper, delivers better fluence, less epidermal damage.Safer in darker skin Skin types I-V
  4. Neodymium: Yttrium-Aluminium-Garnet (Nd: YAG) LaserWavelength: 1064 nmBetter penetration, less epidermal damage, relatively less melanin absorption.Skin types I-VI
  5. Intense Pulse Light (IPL) SystemHigh-intensity pulses of polychromatic, non-coherent light are delivered by a flash-lamp. Various filters allow the narrowing of the emitted wavelength band. Wavelength: 500 to 1200 nmCan be used on darker skinLarger areas can be covered due to its larger spot sizeLess expensiveNot as effective as laser systems 

* Fitzpatrick Skin Types

  • I- Pale white skin, blue/green eyes, blond/red hair; always burns, does not tan
  • II- Fair skin, blue eyes; burns easily, tans poorly
  • III- Darker white skin; tans after the initial burn
  • IV- Light brown skin; burns minimally, tans easily
  • V- Brown skin; rarely burns, tans darkly easily
  • VI- Dark brown or black skin; never burns, always tans darkly

Preparation

  1. Detailed clinical history to rule out infections, drug intake, etc.
  2. Hormonal evaluation to assess causes of hirsutism.
  3. Counsel the patient to keep unrealistic expectations at bay. It must be stressed that the procedure provides permanent hair reduction and not removal.
  4. Evaluate skin and hair types to choose the right laser and parameters.
  5. Avoid hair epilation by plucking or waxing for 6 weeks before the procedure.
  6. Sunscreens may be prescribed 4 to 6 weeks before the procedure, especially on exposed areas.
  7. Pre-procedure photographs, with due consent, to maintain a record for evaluation of treatment response.
  8. Shave the area before the procedure.
  9. Obtain an informed consent.
  10. If need be, a topical anesthetic cream may be applied one-half to one hour before the procedure.

Technique

  1. Clean the area to remove oils from the skin
  2. Position the patient comfortably.
  3. Use eye protection for both the operator as well as the patient.
  4. Avoid reflecting surfaces or metallic objects near the laser.
  5. Individualize the parameters to each patient's skin and hair type and the type of laser being used. 
  6. Place the handpiece perpendicular to the skin. Ensure that it is pressed down gently and firmly to bring the follicles close to the surface and temporarily decrease the blood supply to the local area.
  7. Perifollicular edema and erythema is an expected side effect, and this must be explained to the patient.

Post-Procedure Care

  1. Although most machines have inbuilt cooling systems, ice packs or cooling agents may be used post-procedure to minimize pain and swelling.
  2. In case of inadvertent epidermal injury, topical antibiotics may be used.
  3. Strict sun protection and the use of sunscreens is a must.
  4. Topical steroid creams may be prescribed to minimize erythema and swelling.

The hair matrix being sensitive to laser treatment in the anagen phase necessitates multiple treatments to treat all hairs during this most sensitive phase. In the initial phase, 4 to 6 treatments spaced 4 to 6 weeks apart are a minimum to achieve adequate results. Subsequently, patients may be maintained with repeat treatments once every 6 to 12 months as small vellus hair may grow back.

Various factors may affect the outcome, such as:

  1. Hair location (axillary and pubic hair respond better than hair on the extremities and chest)
  2. Skin and hair color (light skin of Fitzpatrick skin types I-IV with dark hair being most sensitive)
  3. Hair growth stage (anagen hair being most sensitive)
  4. Laser type
  5. Hormonal status
  6. Treatment plan

Complications

Adjacent epidermal structures other than melanin within the hair bulb can compete for absorption, and may cause laser energy to be absorbed by pigment in the epidermis. This hampers the effectiveness of the treatment and causes adverse effects due to adjacent epithelial damage. 

Common adverse effects of laser or IPL-based hair removal include post-treatment erythema, pain, and burning.

More severe adverse effects include blistering, crusting, dyspigmentation, purpura, and sometimes, scarring. Ocular complications due to accidental injury may be seen. Paradoxical hypertrichosis may rarely occur, more commonly in skin types III and with the use of IPL systems.

Clinical Significance

Selecting the correct lasers with the appropriate parameters, individualized to each patient, is very important, particularly in patients with intrinsically dark skin. Most of the complications are preventable when adequate precautions are taken with adjustment of the fluence, spot size, wavelength, and the use of cooling methods. Thus, it is all the more important that trained personnel with a thorough knowledge of the mechanisms, techniques, and complications, carry out these procedures.