A White Paper – Laser Hair Removal: An Application Whose Time has Come
This White Paper was prepared under a clients’ sponsorship, but was prepared on an independent basis by the author. The portion presented here, a part of the complete report, provides the early history of laser-based hair removal. The study was prepared and presented to the client (and sent out to others) in October 1996
Irving J. Arons
Managing Director
Spectrum Consulting
Introduction
Elective cosmetic laser surgery has "exploded" onto the dermatology scene over the past two years, with laser skin resurfacing leading the way. Now that laser ablation of wrinkles by the CO2 laser has been accepted by the dermatological community, the use of lasers to remove unwanted hair will be the next innovation.
In order to help physicians and the laser and financial communities understand this area of laser technology and keep everyone up-to-date, I have looked into the story-behind-the-story in order to put the facts into your hands. In this "white paper", I intend to discuss the market potential for both hair laser manufacturers and service providers; the science and technology of laser hair removal; where the various corporate players stand in their quest to enter or enlarge the market; what the latest clinical results show; and the current patent situation.
This "white paper" was prepared after a comprehensive review of the literature pertaining to the science and technology of hair removal and the companies involved; interviews with key personnel in the industry; and a review of the issued patents. As noted in the disclaimer, all of the companies mentioned were given the opportunity to review and comment on the materials written about them.
It is the author's intention, to provide an unbiased and objective portrait of this evolving application.
The U.S. Market for Hair Removal
Potential Market for Lasers
There are two ways of looking at the potential market for unwanted hair removal: treatment at a salon, the way it is done at present through waxing and electrolysis; or treatment by a physician, where the laser treatment will be performed either by a dermatologist or a cosmetologist working under the physician's direction. I expect the market will be a mixture of both. According to my research, there are currently 24,000 to 26,000 beauty care salons that specialize in either skin care (about 19,000 to 20,000 self-standing units) and 11,000 to 15,000 electrologists, operating either on their own or as part of a beauty/skin care salon. If 15% to 25% of these operations were to get involved in laser hair removal, it would create a market for about 5000 to 9000 laser systems. However, if the market progresses via the professional/physician route, you could expect that 20% to 35% of the U.S.-based 13,000 dermatologist/plastic surgeons might purchase 2600 to 4600 laser systems. But, if both entities get involved, the total potential market could be 7500 to 14,000 systems (or some fraction of that total!). This projects to a market for hair removal laser systems of $600 million to over $1 billion (at an average laser selling price of about $80,000).
Potential Provider Market
According to my research more than 70% of women use depilatories, epilators, shaving or waxing kits on a regular basis to remove unwanted facial and body hair. This market is estimated at $500 to $600 million annually for the 80 million women using these products. In addition, another 1 million women use professional electrologists or have waxing done in a personal care salon. The cost for removal of upper lip facial hairs, for example, can involve multiple half-hour visits over several months and cost in excess of $1000. "Electrolysis is a laborious, painful process that works by heating and coagulating tiny blood vessels in the hair follicles, one at a time. Removing the 1000 to 2000 hairs in a typical moustache can take 30 to 50 visits to an electrolysis center, costing a total of about $1000", according to the director of corporate development of ThermoLase. It is estimated that women (and some men) spend upwards of $1 billion for removal of unwanted hair via the professional salon route.
If the results with the laser are relatively long-lasting (at least six months -- or more), are less painful and quicker than electrolysis, I expect that at least 5 million laser procedures would be done annually, once sufficient laser systems are in place, and would progress to some 20 million annual procedures over time. With the treatment for facial hair costing $750 initially (full backs or legs, for example, would cost considerably more) and dropping to $350 with time and competition, laser hair removal could result in a professional service market of at least $3.75 to $7.0 billion.
Science and Technology
Although, it is not known precisely which portion of the hair growing process needs to be destroyed to provide permanent hair removal, it is believed that the hair follicle, the hair shaft, the hair bulb from which the hair grows, and the hair bulge (located 1 mm below the skin) which controls the growth stage or cycling of the hair, must be effected. The secret for success is to do this without damaging the surrounding dermal tissue and/or the epidermis.
Hair growth proceeds through three cyclic stages, as shown in Figures 2a-d. During the rapid growth or anagen stage, the cells making up the hair shaft proliferate for a fixed duration, growing both outward and inward, which determines the maximum hair length. During the transitional, or catagen stage, the hair matrix cells regress and retract, moving the hair bulb upward toward the hair bulge. Finally, during the resting/dormant or telogen stage, the hair bulb dies and their is no active hair growth until onset of anagen, again, when the old hair shaft is moved upward and out of the skin (hair loss). The hair bulge then prevails to induce new cells to form a new hair bulb and start the process over again, or a renewed anagen stage. Depending upon the location of the hair on the body, the lengths of the anagen (growth) stage of hair cycling may vary. For fast growing areas such as the scalp, beard, and mustache, from 65% to 85% of the hairs may be in the anagen stage; while for slower growing areas such as the legs and thighs or pubic areas, 70% to 80% of the hairs are in the telogen stage. (The catagen stage represents only a short period of a few weeks for all hairs.) The anagen stage can last for months to years, while the telogen stage is measured in weeks to months.
It is not clear yet, which growth stage is most amenable to laser treatment. Although the hair bulb is at its deepest position below the skin during anagen, it is probably most susceptible to death during this proliferation stage. However, because only a percentage of hairs are in the anagen stage at any given time, it will probably take multiple laser treatments to permanently remove all the hair in a given body area. A single treatment will only remove those hairs that are in anagen, while a second treatment, several months later may be necessary to affect the new hairs that are then beginning or are progressing through their anagen growth stage. Multiple treatments consistent with the follicular cycling are probably needed for permanent hair removal.
There are several different approaches on how to accomplish laser hair removal, and the clinical data to support the various methodologies used is still being developed. Let me first describe the several approaches.
Laser-Based Approaches
ThermoLase, the first company to gain FDA marketing approval for their approach (in April 1995), uses the concept of delivering carbon black particles ("India ink") as the laser energy absorber, from a surface applied cream or lotion, into the hair follicles (following epilation or waxing to remove the hair shafts to allow the diffusion of the particles into the follicles). The company then uses a Q-switched pulsed Nd:YAG laser, similar to the pulsed YAG laser used to remove tattoos, to selectively heat the target particles, imparting that heat to the hair follicles (and hopefully to the hair bulb). In reality, the follicle destruction is probably accomplished by micro-explosions/fracture of the carbon particles, again, similar to the removal of black tattoos, causing shock waves and cavitation to create local damage, rather than through transfer of the small amount of heat energy absorbed by the carbon particles, which would quickly dissipate into surrounding tissue structures.
In use, the process is quite time consuming, as waxing or epilation of the area to be treated must first be done, followed by application of the carbon-containing lotion, massaging the lotion into the skin (and hair follicles), and removal of the topical coating. This is followed by passing the laser over the treatment zone, using a 5-6 mm spot. After treatment, the skin is cleaned, moisturized, and again massaged. A topical anesthetic/cooling lotion is applied for pain control. Depending on the size of the area treated and because of the small diameter laser spot, the hair removal process can take an hour or more.
Both Palomar Medical Technologies and Laser Industries/Sharplan (as well as Mehl/Biophile), rely on "selective photothermolysis" for effectively removing the unwanted hair. This phenomenon, invented by Drs. John Parrish and Rox Anderson of the Wellman Laboratories of Photomedicine at Massachusetts General Hospital, uses the principle of delivering pulsed laser energy to a selected chromophore within the target tissue, without damaging surrounding tissue. In the case of hair removal, the chromophore is melanin, found both within the hair shaft and in its surrounding covering (the follicle). The use of a ruby laser, operating at 694 nm, allows both penetration of the laser energy into the dermal tissue, as well as selective absorption by the melanin chromophore, with little absorption by other chromophores in the tissue (namely hemoglobin). One problem, however, is that melanin is also present at the base of the epidermis, at its interface with the dermis, which could conceivably block the laser energy from reaching deep within the hair follicle. Both Palomar and Laser Industries have found a way around this dilemma. By carefully selecting the pulse width of the laser beam, researchers for both companies have found that the laser energy can be delivered to the melanin within the hair follicle, while minimizing enery deposition into the melanin contained in the epidermal tissue. Also, by using cooling devices, the surface tissue can be selectively cooled, reducing potential surface skin damage as the heat absorbed by the melanin at the base of the epidermis is quickly and selectively removed.
As put by Dr. Melanie Grossman and the Wellman team in a soon to be published clinical report on the effects of long-pulse ruby energy on hair removal, "In theory, the optimal pulse duration for selective photothermolysis is less than or about equal to the thermal relaxation time of the target structure." According to the theory, the thermal relaxation time, in seconds, is about equal to the square of the target dimension, in millimeters. For a hair follicle about 200-300 microns in diameter, the thermal relaxation time would be in the range of 40-100 ms, and the ideal pulse duration should fall within that range. Further, since the epidermis thickness is about 100 microns, its critical pulse width would be in the range of 3-10 ms. With a pulsewidth setting of about 30-50 ms, the epidermis should not be harmed while heat is concentrated in the target melanin in the hair follicle and shaft as desired. (It should be noted that the researchers performed the clinical work reported in this Wellman Laboratory study at 270 us, well below the estimated thermal relaxation time/pulse widths that are considered as ideal.)
The idea is to choose a long pulsewidth (3-10 ms) to minimize laser energy absorption in the thin layer of melanin within the epidermis, and thus spare damage to this layer of skin. But, according to the Wellman Lab researchers, this approach is safe and effective at 3 ms, although it would be even better if a longer pulsewidth could be used, especially with darker skinned individuals. The problem is the technical difficulty of achieving pulse widths longer than about 3 ms with normal-running ruby lasers. This is technically difficult and expensive to do.
Both Palomar and Laser Industries/Sharplan (and Mehl/Biophile) use long-pulse ruby lasers, with Mehl/Biophile using 0.5 ms pulsewidths; Sharplan 0.8 ms; while Palomar's laser is set to operate at 3 ms pulses.
Another critical laser parameter is the ability to deliver the laser energy deep into the dermis to destroy the hair bulb, which typically lies 3-4 mm below the skin surface. (The depth of the hair bulb can be anywhere from 1 mm to 7 mm below the skin surface, depending on the body area.) Because of optical scattering and reflectance caused by the tissue, only a fraction of the laser energy applied to the skin surface is delivered to the target. In the case of the MGH/Wellman/Palomar approach, an actively cooled glass sapphire prism/lens is used to deliver a convergent beam (20 mm focal length) to the skin surface. Also, by pressing the lens against the skin surface, conduction of heat from the epidermis is accomplished both before, during, and after each laser pulse. The forceful compression of the skin both eliminates blood from the area and reduces the distance between the surface and the target.
Laser Industries/Sharplan also uses a cooling device and a transparent gel to optimize the laser beam coupling into the skin and minimize reflectance and scattering. The cooling device ensures deep cooling of the dermis and epidermis to avoid skin temperature elevation and acts to contract blood vessels in the vicinity.
Another variable is laser spot size. Both Laser Industries/Sharplan and Mehl/Biophile use about a 5 mm laser spot, while Palomar, with a higher energy, dedicated laser, uses a 10-12 mm spot. The larger spot means that more hairs can be treated with a single pulse. The larger spot also increases the depth of penetration of laser energy by more closely approximating a planar diffusion geometry. The 2½ times larger spot size enables their laser to treat 5 times more hairs per unit area. Depending on the location of the body being treated, the number of hair follicles per square centimeter vary from about 60-70 hairs (arms, legs and thighs, trunk and pubic area) to 350-800 hairs (scalp, cheeks, beard, moustache/upper lip).
And then finally there is laser fluence. In order to obtain temperatures in the range of 70-100°C deep into the hair shaft and bulb, as well as to the hair bulge, for effective destruction of these bodies, a fluence level of about 30-40 J/cm2 at the skin surface is required to overcome optical scattering and reflectance. There is also a dependency on a minimum spot size of at least 2 mm to get depth penetration of the laser energy. With a small spot of 2-3 mm, a lower powered laser can be used, still achieving the desired fluence, but only one, or two hairs at most, are removed per treatment pulse. Conversely, a larger delivered spot size of 5-12 mm would remove more hairs per single treatment, but requires a higher-powered laser.
Both Palomar and Sharplan shave the area to be treated to allow the laser energy to reach down into the hair follicles. This is followed by application of the clear gel and the cooling device, in Sharplan's case, prior to use of the laser. Single pulses of laser energy are applied to each area of skin to be treated. For the Palomar method, the cooling of the epidermis is accomplished via the laser handpiece which contains an active cooling system attached to the sapphire lens applied directly to the skin. In both cases, post-treatment includes use of a moisturizer lotion and/or an anti-bacterial/anti-inflammatory cream if needed.
Non-Laser Based Approaches
In addition to the various laser-based approaches noted above, there are at least two companies using non-laser based light energy approaches to hair removal.
ESC Medical Systems has adapted its intense, pulsed, flashlamp light energy delivery system, used primarily for the treatment of vascular lesions, for the selective heating of hair follicles, similar to the approach taken with lasers mentioned above. Since a broad beam of filtered light can be delivered by the ESC system, supposedly a large area of skin can be epilated with a single pulse. It remains to be seen if the safety and efficacy of this broad beam energy system can be proven for effective hair removal without damaging the epidermal tissue. (Company officials have assured me, however, that their technique is safe and efficacious.) It is believed that a cooling gel is applied to the skin's surface to reduce possible damage. The major advantages of this non-laser approach appear to be the larger spot size that enables removal of large amounts of hair with a single treatment and the ability to adjust the wavelength and pulse width in accordance with skin and hair color.
DUSA Pharmaceuticals has adapted its photodynamic therapy approach, used for treating skin abnormalities and cancers, to the selective removal of unwanted hair. By applying a lotion or cream containing its lead drug, aminolevulinic acid (ALA), to the skin surface, it is believed that the active drug penetrates into the hair follicle where it stimulates the synthesis of protoporphyrin, a photosensitizer, which upon activation with a red light source (laser or non-laser) forms singlet oxygen which destroys the host cells.
In use, the body area to be treated is waxed to remove the hair, followed by application of the lotion containing the ALA drug. A few hours wait is required to allow accumulation of the protoporphyrin in the target hair follicles, after which the treatment area is exposed to a red light source for a few minutes. The advantages of the system are its low cost and the ability to treat large areas of the body in a single treatment. The DUSA approach is independent of hair or skin color. The only drawback of the system in pilot studies to date has been the need to apply the ALA lotion hours ahead of the light treatment.
This technology is still in an early developmental stage and much experimentation with appropriate drug dose and light energy levels remains to be done.
Irving J. Arons
Managing Director
Spectrum Consulting
Introduction
Elective cosmetic laser surgery has "exploded" onto the dermatology scene over the past two years, with laser skin resurfacing leading the way. Now that laser ablation of wrinkles by the CO2 laser has been accepted by the dermatological community, the use of lasers to remove unwanted hair will be the next innovation.
In order to help physicians and the laser and financial communities understand this area of laser technology and keep everyone up-to-date, I have looked into the story-behind-the-story in order to put the facts into your hands. In this "white paper", I intend to discuss the market potential for both hair laser manufacturers and service providers; the science and technology of laser hair removal; where the various corporate players stand in their quest to enter or enlarge the market; what the latest clinical results show; and the current patent situation.
This "white paper" was prepared after a comprehensive review of the literature pertaining to the science and technology of hair removal and the companies involved; interviews with key personnel in the industry; and a review of the issued patents. As noted in the disclaimer, all of the companies mentioned were given the opportunity to review and comment on the materials written about them.
It is the author's intention, to provide an unbiased and objective portrait of this evolving application.
The U.S. Market for Hair Removal
Potential Market for Lasers
There are two ways of looking at the potential market for unwanted hair removal: treatment at a salon, the way it is done at present through waxing and electrolysis; or treatment by a physician, where the laser treatment will be performed either by a dermatologist or a cosmetologist working under the physician's direction. I expect the market will be a mixture of both. According to my research, there are currently 24,000 to 26,000 beauty care salons that specialize in either skin care (about 19,000 to 20,000 self-standing units) and 11,000 to 15,000 electrologists, operating either on their own or as part of a beauty/skin care salon. If 15% to 25% of these operations were to get involved in laser hair removal, it would create a market for about 5000 to 9000 laser systems. However, if the market progresses via the professional/physician route, you could expect that 20% to 35% of the U.S.-based 13,000 dermatologist/plastic surgeons might purchase 2600 to 4600 laser systems. But, if both entities get involved, the total potential market could be 7500 to 14,000 systems (or some fraction of that total!). This projects to a market for hair removal laser systems of $600 million to over $1 billion (at an average laser selling price of about $80,000).
Potential Provider Market
According to my research more than 70% of women use depilatories, epilators, shaving or waxing kits on a regular basis to remove unwanted facial and body hair. This market is estimated at $500 to $600 million annually for the 80 million women using these products. In addition, another 1 million women use professional electrologists or have waxing done in a personal care salon. The cost for removal of upper lip facial hairs, for example, can involve multiple half-hour visits over several months and cost in excess of $1000. "Electrolysis is a laborious, painful process that works by heating and coagulating tiny blood vessels in the hair follicles, one at a time. Removing the 1000 to 2000 hairs in a typical moustache can take 30 to 50 visits to an electrolysis center, costing a total of about $1000", according to the director of corporate development of ThermoLase. It is estimated that women (and some men) spend upwards of $1 billion for removal of unwanted hair via the professional salon route.
If the results with the laser are relatively long-lasting (at least six months -- or more), are less painful and quicker than electrolysis, I expect that at least 5 million laser procedures would be done annually, once sufficient laser systems are in place, and would progress to some 20 million annual procedures over time. With the treatment for facial hair costing $750 initially (full backs or legs, for example, would cost considerably more) and dropping to $350 with time and competition, laser hair removal could result in a professional service market of at least $3.75 to $7.0 billion.
Science and Technology
Although, it is not known precisely which portion of the hair growing process needs to be destroyed to provide permanent hair removal, it is believed that the hair follicle, the hair shaft, the hair bulb from which the hair grows, and the hair bulge (located 1 mm below the skin) which controls the growth stage or cycling of the hair, must be effected. The secret for success is to do this without damaging the surrounding dermal tissue and/or the epidermis.
Hair growth proceeds through three cyclic stages, as shown in Figures 2a-d. During the rapid growth or anagen stage, the cells making up the hair shaft proliferate for a fixed duration, growing both outward and inward, which determines the maximum hair length. During the transitional, or catagen stage, the hair matrix cells regress and retract, moving the hair bulb upward toward the hair bulge. Finally, during the resting/dormant or telogen stage, the hair bulb dies and their is no active hair growth until onset of anagen, again, when the old hair shaft is moved upward and out of the skin (hair loss). The hair bulge then prevails to induce new cells to form a new hair bulb and start the process over again, or a renewed anagen stage. Depending upon the location of the hair on the body, the lengths of the anagen (growth) stage of hair cycling may vary. For fast growing areas such as the scalp, beard, and mustache, from 65% to 85% of the hairs may be in the anagen stage; while for slower growing areas such as the legs and thighs or pubic areas, 70% to 80% of the hairs are in the telogen stage. (The catagen stage represents only a short period of a few weeks for all hairs.) The anagen stage can last for months to years, while the telogen stage is measured in weeks to months.
It is not clear yet, which growth stage is most amenable to laser treatment. Although the hair bulb is at its deepest position below the skin during anagen, it is probably most susceptible to death during this proliferation stage. However, because only a percentage of hairs are in the anagen stage at any given time, it will probably take multiple laser treatments to permanently remove all the hair in a given body area. A single treatment will only remove those hairs that are in anagen, while a second treatment, several months later may be necessary to affect the new hairs that are then beginning or are progressing through their anagen growth stage. Multiple treatments consistent with the follicular cycling are probably needed for permanent hair removal.
There are several different approaches on how to accomplish laser hair removal, and the clinical data to support the various methodologies used is still being developed. Let me first describe the several approaches.
Laser-Based Approaches
ThermoLase, the first company to gain FDA marketing approval for their approach (in April 1995), uses the concept of delivering carbon black particles ("India ink") as the laser energy absorber, from a surface applied cream or lotion, into the hair follicles (following epilation or waxing to remove the hair shafts to allow the diffusion of the particles into the follicles). The company then uses a Q-switched pulsed Nd:YAG laser, similar to the pulsed YAG laser used to remove tattoos, to selectively heat the target particles, imparting that heat to the hair follicles (and hopefully to the hair bulb). In reality, the follicle destruction is probably accomplished by micro-explosions/fracture of the carbon particles, again, similar to the removal of black tattoos, causing shock waves and cavitation to create local damage, rather than through transfer of the small amount of heat energy absorbed by the carbon particles, which would quickly dissipate into surrounding tissue structures.
In use, the process is quite time consuming, as waxing or epilation of the area to be treated must first be done, followed by application of the carbon-containing lotion, massaging the lotion into the skin (and hair follicles), and removal of the topical coating. This is followed by passing the laser over the treatment zone, using a 5-6 mm spot. After treatment, the skin is cleaned, moisturized, and again massaged. A topical anesthetic/cooling lotion is applied for pain control. Depending on the size of the area treated and because of the small diameter laser spot, the hair removal process can take an hour or more.
Both Palomar Medical Technologies and Laser Industries/Sharplan (as well as Mehl/Biophile), rely on "selective photothermolysis" for effectively removing the unwanted hair. This phenomenon, invented by Drs. John Parrish and Rox Anderson of the Wellman Laboratories of Photomedicine at Massachusetts General Hospital, uses the principle of delivering pulsed laser energy to a selected chromophore within the target tissue, without damaging surrounding tissue. In the case of hair removal, the chromophore is melanin, found both within the hair shaft and in its surrounding covering (the follicle). The use of a ruby laser, operating at 694 nm, allows both penetration of the laser energy into the dermal tissue, as well as selective absorption by the melanin chromophore, with little absorption by other chromophores in the tissue (namely hemoglobin). One problem, however, is that melanin is also present at the base of the epidermis, at its interface with the dermis, which could conceivably block the laser energy from reaching deep within the hair follicle. Both Palomar and Laser Industries have found a way around this dilemma. By carefully selecting the pulse width of the laser beam, researchers for both companies have found that the laser energy can be delivered to the melanin within the hair follicle, while minimizing enery deposition into the melanin contained in the epidermal tissue. Also, by using cooling devices, the surface tissue can be selectively cooled, reducing potential surface skin damage as the heat absorbed by the melanin at the base of the epidermis is quickly and selectively removed.
As put by Dr. Melanie Grossman and the Wellman team in a soon to be published clinical report on the effects of long-pulse ruby energy on hair removal, "In theory, the optimal pulse duration for selective photothermolysis is less than or about equal to the thermal relaxation time of the target structure." According to the theory, the thermal relaxation time, in seconds, is about equal to the square of the target dimension, in millimeters. For a hair follicle about 200-300 microns in diameter, the thermal relaxation time would be in the range of 40-100 ms, and the ideal pulse duration should fall within that range. Further, since the epidermis thickness is about 100 microns, its critical pulse width would be in the range of 3-10 ms. With a pulsewidth setting of about 30-50 ms, the epidermis should not be harmed while heat is concentrated in the target melanin in the hair follicle and shaft as desired. (It should be noted that the researchers performed the clinical work reported in this Wellman Laboratory study at 270 us, well below the estimated thermal relaxation time/pulse widths that are considered as ideal.)
The idea is to choose a long pulsewidth (3-10 ms) to minimize laser energy absorption in the thin layer of melanin within the epidermis, and thus spare damage to this layer of skin. But, according to the Wellman Lab researchers, this approach is safe and effective at 3 ms, although it would be even better if a longer pulsewidth could be used, especially with darker skinned individuals. The problem is the technical difficulty of achieving pulse widths longer than about 3 ms with normal-running ruby lasers. This is technically difficult and expensive to do.
Both Palomar and Laser Industries/Sharplan (and Mehl/Biophile) use long-pulse ruby lasers, with Mehl/Biophile using 0.5 ms pulsewidths; Sharplan 0.8 ms; while Palomar's laser is set to operate at 3 ms pulses.
Another critical laser parameter is the ability to deliver the laser energy deep into the dermis to destroy the hair bulb, which typically lies 3-4 mm below the skin surface. (The depth of the hair bulb can be anywhere from 1 mm to 7 mm below the skin surface, depending on the body area.) Because of optical scattering and reflectance caused by the tissue, only a fraction of the laser energy applied to the skin surface is delivered to the target. In the case of the MGH/Wellman/Palomar approach, an actively cooled glass sapphire prism/lens is used to deliver a convergent beam (20 mm focal length) to the skin surface. Also, by pressing the lens against the skin surface, conduction of heat from the epidermis is accomplished both before, during, and after each laser pulse. The forceful compression of the skin both eliminates blood from the area and reduces the distance between the surface and the target.
Laser Industries/Sharplan also uses a cooling device and a transparent gel to optimize the laser beam coupling into the skin and minimize reflectance and scattering. The cooling device ensures deep cooling of the dermis and epidermis to avoid skin temperature elevation and acts to contract blood vessels in the vicinity.
Another variable is laser spot size. Both Laser Industries/Sharplan and Mehl/Biophile use about a 5 mm laser spot, while Palomar, with a higher energy, dedicated laser, uses a 10-12 mm spot. The larger spot means that more hairs can be treated with a single pulse. The larger spot also increases the depth of penetration of laser energy by more closely approximating a planar diffusion geometry. The 2½ times larger spot size enables their laser to treat 5 times more hairs per unit area. Depending on the location of the body being treated, the number of hair follicles per square centimeter vary from about 60-70 hairs (arms, legs and thighs, trunk and pubic area) to 350-800 hairs (scalp, cheeks, beard, moustache/upper lip).
And then finally there is laser fluence. In order to obtain temperatures in the range of 70-100°C deep into the hair shaft and bulb, as well as to the hair bulge, for effective destruction of these bodies, a fluence level of about 30-40 J/cm2 at the skin surface is required to overcome optical scattering and reflectance. There is also a dependency on a minimum spot size of at least 2 mm to get depth penetration of the laser energy. With a small spot of 2-3 mm, a lower powered laser can be used, still achieving the desired fluence, but only one, or two hairs at most, are removed per treatment pulse. Conversely, a larger delivered spot size of 5-12 mm would remove more hairs per single treatment, but requires a higher-powered laser.
Both Palomar and Sharplan shave the area to be treated to allow the laser energy to reach down into the hair follicles. This is followed by application of the clear gel and the cooling device, in Sharplan's case, prior to use of the laser. Single pulses of laser energy are applied to each area of skin to be treated. For the Palomar method, the cooling of the epidermis is accomplished via the laser handpiece which contains an active cooling system attached to the sapphire lens applied directly to the skin. In both cases, post-treatment includes use of a moisturizer lotion and/or an anti-bacterial/anti-inflammatory cream if needed.
Non-Laser Based Approaches
In addition to the various laser-based approaches noted above, there are at least two companies using non-laser based light energy approaches to hair removal.
ESC Medical Systems has adapted its intense, pulsed, flashlamp light energy delivery system, used primarily for the treatment of vascular lesions, for the selective heating of hair follicles, similar to the approach taken with lasers mentioned above. Since a broad beam of filtered light can be delivered by the ESC system, supposedly a large area of skin can be epilated with a single pulse. It remains to be seen if the safety and efficacy of this broad beam energy system can be proven for effective hair removal without damaging the epidermal tissue. (Company officials have assured me, however, that their technique is safe and efficacious.) It is believed that a cooling gel is applied to the skin's surface to reduce possible damage. The major advantages of this non-laser approach appear to be the larger spot size that enables removal of large amounts of hair with a single treatment and the ability to adjust the wavelength and pulse width in accordance with skin and hair color.
DUSA Pharmaceuticals has adapted its photodynamic therapy approach, used for treating skin abnormalities and cancers, to the selective removal of unwanted hair. By applying a lotion or cream containing its lead drug, aminolevulinic acid (ALA), to the skin surface, it is believed that the active drug penetrates into the hair follicle where it stimulates the synthesis of protoporphyrin, a photosensitizer, which upon activation with a red light source (laser or non-laser) forms singlet oxygen which destroys the host cells.
In use, the body area to be treated is waxed to remove the hair, followed by application of the lotion containing the ALA drug. A few hours wait is required to allow accumulation of the protoporphyrin in the target hair follicles, after which the treatment area is exposed to a red light source for a few minutes. The advantages of the system are its low cost and the ability to treat large areas of the body in a single treatment. The DUSA approach is independent of hair or skin color. The only drawback of the system in pilot studies to date has been the need to apply the ALA lotion hours ahead of the light treatment.
This technology is still in an early developmental stage and much experimentation with appropriate drug dose and light energy levels remains to be done.
posted by Irv Arons @ 6:03 PM
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