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The use of lasers for dermatological conditions
What's new in ... The use of lasers for dermatological conditions Sajjad Rajpar and Sean Lanigan
There have been significant advances in the use of lasers for skin disorders. New generation pulsed dye lasers and dual wavelength lasers have optimized the treatment of vascular lesions such as port wine stains. The improved safety of lasers for hair removal has enabled children with pathologically excessive hair to be treated safely, and for treatment to be carried out on dark-skinned individuals. Exogenous melanin and radiofrequency devices have made epilation of light-coloured hair possible. The pulsed dye laser and intense pulsed light devices may improve active inflammatory acne, and can be used as optical sources for photodynamic therapy in the treatment of cutaneous dysplasias including actinic keratoses. Fractional resurfacing technology has bridged the gap between ablative resurfacing lasers and non-ablative lasers. Pneumatic suction devices may improve comfort and efficacy of treatment and are available as an attachment for existing lasers or integrated into handpieces. Keywords acne; dual wavelength lasers; fractional resurfacing; hair removal; intense pulsed light; lasers; melanin; optical clearing agents; photodynamic therapy; pneumatic suction devices; port wine stains; vascular lesions
Lasers have been used for the treatment of cutaneous disorders for over 30 years. Technological advances have led to the availability of a wide range of devices that are powerful, versatile and costeffective, enabling an increasing range of conditions to be treated safely and effectively. Lasers emit high intensity light of a single (monochromatic) wavelength, which is absorbed by target structures in the skin and converted to heat energy. This key principle underlies the interaction between light and biological tissues
and is known as the theory of selective photothermolysis (Figure 1).1 The main targets (chromophores) in the skin are oxyhaemoglobin, contained in blood, and melanin, contained in hair follicles and pigmented lesions. Other targets include tissue water and tattoo pigments. Selective heating of target structures produces clinically appreciable effects, while heating of non-target structure leads to unwanted side effects. Intense pulsed light (IPL) devices are, like lasers, sources of high-energy light.
However, IPLs are polychromatic and emit multiple wavelengths with each pulse. Filters with different cut off values tailor the wavelength range that is emitted to the cutaneous target of interest. The efficacy of IPLs can be explained by the fact that chromophores absorb light over a wide range of wavelengths, and so monochromacity is not a prerequisite for selective targeting. IPLs can, therefore, be used in some conditions that are responsive to lasers.
Advances in the treatment of existing indications Sajjad Rajpar MBChB (Hons) MRCP is a final year Specialist Registrar in Dermatology at the Birmingham Skin Centre, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, UK. His main interests are in dermatologic lasers and cutaneous oncology. Competing interests: none declared. Sean Lanigan MD FRCP DCH is a Consultant Dermatologist at City Hospital, Birmingham, UK. He is a recognized national leader in cutaneous laser therapy and has authored over 140 medical publications and the only European textbook in this field. Competing interests: Dr Lanigan is salaried Medical Director of Sk:n limited a nationwide provider of aesthetic cutaneous and laser treatments. He has received research grants, honoraria or equipment loans from the following laser manufacturers: Candela, Alma, Cynosure, Omnilux, Laserscope, Reliant, Lynton and Palomar.
MEDICINE 35:8
473
Vascular lesions The pulsed dye laser (PDL) revolutionized the treatment of port wine stains (PWS) when it was introduced 20 years ago. PWS are vascular malformations composed of ectatic dermal vessels, and affect 1 in 200 individuals. Lesions located in the area supplied by the ophthalmic division of the trigeminal nerve may be associated with leptomeningeal angiomas (Sturge-Weber syndrome). PWS can be disfiguring, cause glaucoma
© 2007 Elsevier Ltd. All rights reserved.
WHAT'S NEW
Absorption coefficient
Absorption spectra of melanin and oxyhaemoglobin, the two main target structures (chromophores) in the skin
Oxyhaemoglobin
Melanin
400
500
600
700
800
Wavelength (mm) Figure 1
and become thick and hypertrophic in adulthood. The current trend is to treat lesions during the pre-school period in order to minimize these complications. Thermal damage to blood vessels during laser treatment leads to a reduction in the number and size of blood vessels producing an observable lightening of lesions. First-generation PDLs operated at wavelengths of 577 or 585 nm, and produced significant lightening in 40% of patients. A major development has been the modification of first-generation PDLs to include longer wavelengths (595−600 nm), more power and better skin cooling. This has led to more effective clearance of PWS, including those that have been resistant to first-generation PDLs. Despite this, at least 20% of PWS fail to respond, and one-third re-darken in the 10 years after treatment.2 Strategies under investigation that may overcome these inadequacies include the use of suction devices (discussed below) and dual wavelength lasers.3 An example of the latter is the Cynergy PL (Cynosure, MA, USA), which emits a pulse at 585 nm followed by a pulse at 1064 nm. The initial pulse targets superficial vessels converting oxyhaemoglobin to methaemoglobin. The second pulse has a longer wavelength and penetrates deeper into the skin. It targets deeper blood vessels, but is also better absorbed by the recently formed methaemoglobin in superficial vessels. In combination, the dual pulses allow the delivery of more energy to vessels of varying depths,
MEDICINE 35:8
which may translate to better rates of clearance of PWS. Hair removal The leading use of lasers in the commercial sector is for hair removal. A prospective analysis of 3143 laser treatments in 373 patients conducted at our unit has demonstrated that laser-assisted hair removal with the ruby, alexandrite and Nd:YAG lasers is safe with a very low incidence of persisting side effects.4 Individuals with fair skin and darkly pigmented hair are considered the best candidates and, after a course of 6 treatments, can obtain a 60−70% reduction in hair counts at 2 years. Energy is absorbed by melanin in hair shafts and diffuses out to damage surrounding follicular structures. It is still unclear whether the cellular target is the hair follicular epithelium, stem cells in the bulge region or the dermal papillae. The development of long pulse (1064 nm) lasers has enabled the treatment of dark skinned individuals, who are prone to epidermal side effects such as blistering and dyspigmentation with traditional hair removal lasers (such as the 694 nm ruby laser). Longer wavelengths penetrate deeper into the skin, and are less likely to be competitively absorbed by melanin in the epidermis, which is abundant in darkly pigmented individuals. Improvements in cooling technologies that protect the epidermis by lowering its temperature have also facilitated safer hair removal in darker individuals. The long pulsed 474
Nd:YAG is therefore the laser of choice for hair removal in darker skin types, and also useful for pseudofolliculitis barbae which can otherwise be quite resistant to conventional treatment. In this condi tion, which predominates in AfricanCaribbean males, hair may grow back into follicles and cause inflammatory papules which frequently scar. In one study of 26 patients with dark skin types, there was a 61% reduction in papule count after one treatment with the long pulsed Nd:YAG.5 A single case report has also shown efficacy of this laser in recalcitrant folliculitis decalvans, another follicular inflammatory disorder.6 Children may suffer from localized hypertrichosis, generalized hypertrichosis and hirsutism. These conditions can lead to significant psychosocial distress. A recent retrospective case series demonstrated that laser hair removal was safe and well tolerated in children under the age of 16.7 Conventional lasers cannot treat white, grey and blond hair as the lack of melanin prevents localization of laser energy to the hair shaft. Exogenous melanin in the form of a phosphatidylcholine-based liposome solution (Meladine: Creative Technologies, USA) can be applied before laser treatment to temporarily increase follicular melanin. This permits laser removal of light coloured hairs though at a significantly greater expense. A combined radiofrequency and IPL device (Aurora SR: Syneron, Toronot, Canada) has also been shown to be effective for lightly pigmented hair, as the delivery of radiofrequency energy to hair follicles is claimed to be independent of hair colour.8
New devices and indications Fractional resurfacing The C02 and Er:YAG lasers are used for resurfacing. They target tissue water and non-specifically ablate layers of skin to varying depths. Significant improvements can be obtained with these lasers for scars (including those from acne vulgaris), birthmarks (such as congenital melanocytic naevi) and cutaneous growths (such as adenoma sebaceum of tuberous sclerosis). However, recovery can be protracted and several side effects are recognized, including dyspigmentation, scarring and prolonged
© 2007 Elsevier Ltd. All rights reserved.
WHAT'S NEW
Fractional resurfacing a
b
a There is contiguous tissue damage with conventional resurfacing lases. b There are small columns of laser injury with fractional resurfacing devices, with sparing of intervening skin. This permits a more rapid recovery.
Figure 2
erythema. A new laser technology, fractional photothermolysis, has recently been introduced to specifically overcome the drawbacks of conventional resurfacing.9 Instead of producing one beam that causes even thermal damage to tissue in its path (as with conventional resurfacing lasers), the output from fractional resurfacing devices consists of thousands of microscopic columns, which each produce thermal damage to a small volume of tissue (Figure 2).
As ablation is non-confluent, the risk of scarring is reduced and recovery is rapid, with epidermal healing taking only 24 hours by means of keratinocyte migration. Side effects last 24 to 48 hours, and consist mainly of erythema and oedema. The procedure can be performed under topical anaesthesia with slight discomfort. Although promising, this technology is still in its infancy and optimum treatment frequency and parameters remain to be defined.
Photodynamic therapy Photodynamic is used in dermatology for various disorders, including actinic keratoses and Bowen's disease (forms of in situ squamous cell carcinoma). 5-aminolaevulinate cream is applied to lesions under occlusion for 4 hours. Dysplastic cells preferentially take up the 5-aminolaevulinate where it saturates the haem biosynthesis pathway leading to an excess of intracellular protoporphyrin IX (PpIX: an endogenous photosensitizer). Conventionally, light, at a wavelength capable of activating PpIX (usually in the red spectrum), is then applied for 10 to 60 minutes. Photoactivated PpIX produces highly reactive free radicals and singlet oxygen intermediates that lead to cell death. It has recently been shown that the PDL and IPL are an effective light source for photodynamic therapy,10 with the advantage of a shorter treatment time, less pain, less post treatment erythema, faster recover and the ability to treat multiple widespread lesions at one sitting. Lesions that have been shown to improve with PDL or IPL photodynamic therapy (PDT) include actinic keratoses,11,12 viral warts, inflammatory acne, sebaceous gland hyperplasia and lichen sclerosus.
Acne vulgaris Acne vulgaris is among the commonest human dermatoses, affecting 90% of teenagers at some stage. Conventional treatment options are limited due to being
Improvement of acne vulgaris with the pulsed dye laser. Occasionally, individuals may have a good response to pulsed dye laser monotherapy for acne vulgaris, though this is unusual in our experience. Figure 3
MEDICINE 35:8
475
© 2007 Elsevier Ltd. All rights reserved.
WHAT'S NEW
ineffective, intolerable or having high non-compliance levels. There are also concerns about bacterial resistance with long-term antibiotic use. A recent study showed a significant reduction in the severity of acne after a single treatment with the PDL,13 though a subsequent splitface randomized controlled trial failed to show any effect (Figure 3).14 Lasers in the mid-infrared range, that cause dermal heating and thermal injury to sebaceous glands, have also been reported to improve active acne. This includes the 1320 nm Nd:YAG laser, the 1450 nm diode laser and the 1540 nm Erbium glass laser. Lasers are increasingly used in an adjuvant role to conventional acne treatments, although several controlled trials are underway which will help clarify their role further.
Adaptations that increase the efficacy of devices Pneumatic suction devices Pneumatic suction devices are a recent enhancement to existing lasers and IPLs. A negative pressure is applied to the skin before the pulse is delivered. This gently pulls and stretches the skin so as to thin the epidermis, reduce the density of epidermal melanin, bring the dermis closer to the light source and activate sensory fibres, thereby reducing the transmission of pain. As a result, lower energies are required, there is theoretically a lower propensity for side effects, and treatment is more comfortable. Negative pressure may also increase the volume of dermal vessels.15 Expanded vessels concentrate laser energy better as they contain more blood. Pneumatic suction devices may be integrated into the laser or IPL handpiece (e.g. Aesthera PPx, Pleasanton, CA, USA) or a separate attachment that can be
MEDICINE 35:8
used with existing systems (e.g. Inolase, Candela Corp, Boston, USA). Optical clearing agents A significant proportion of the light emitted by lasers is scattered by the epidermis.16 Non-human and laboratory data have shown that hyperosmotic chemicals such as glycerol and propylene glycol enhance penetration of light to dermal targets by reducing scattering in the epidermis. This has the potential of improving the efficacy of lasers and reducing unwanted epidermal injury. Optical clearing agents are currently impractical to use in the clinical context, and refinements in the epidermal delivery mechanism of these agents are awaited. ◆
References 1 Anderson RR, Parish JA. Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation. Science 1983; 220: 524–27. 2 Huikeshoven M, Koster PH, de Borgie CA, et al. Redarkening of port-wine stains 10 years after pulsed-dye-laser treatment. N Engl J Med 2007; 356: 1235–40. 3 Ahcan U, Zorman P, Recek D, et al. Port wine stain treatment with a dualwavelength Nd:Yag laser and cryogen spray cooling: a pilot study. Lasers Surg Med 2004; 34: 164–67. 4 Lanigan SW. Incidence of side effects after laser hair removal. J Am Acad Dermatol 2003; 49: 882–86. 5 Ross EV, Cooke LM, Overstreet KA, et al. Treatment of pseudofolliculitis barbae in very dark skin with a long pulse Nd:YAG laser. J Natl Med Assoc 2002; 94: 888–93. 6 Parlette EC, Kroeger N, Ross EV. Nd:YAG laser treatment of recalcitrant folliculitis
476
decalavans. Dermatol Surg 2004; 30: 1152–54. 7 Rajpar SF, Hague J, Abdullah A. Laser hair removal is safe and well tolerated in children. Br J Dermatol 2006; 155(suppl 1). 8 Sadick NS, Shaoul J. Hair removal using a combination of conducted radiofrequency and optical energies – an 18 month follow up. J Cosmet Laser Ther 2004; 6: 21–26. 9 Manstein D, Herron GS, Sink RK, Tanner H, Anderson RR. Fractional photothermolysis: A new concept for cutaneous remodeling using microscopic patterns of thermal injury. Lasers Surg Med 2004; 34: 426–38. 10 Brancaleon L, Moseley H. Laser and non-laser light sources for photodynamic therapy. Lasers Med Sci 2002; 17: 173–86. 11 Alexiades-Armenakas MR, Geronemus RG. Laser-mediated photodynamic therapy of actinic cheilitis. J Drugs Dermatol 2004; 3: 548–51. 12 Kim HS, Yoo JY, Cho KH, Kwon OS, Moos SE. Topical photodynamic therapy using intense pulsed light for treatment of actinic keratosis: clinical and histopathologic evaluation. Dermatol Surg 2005; 31: 33–37. 13 Seaton ED, Charakida A, Mouser PE, Grace I, Clement RM, Chu AC. Pulsed-dye laser treatment for inflammatory acne vulgaris: randomised controlled trial. Lancet 2003; 362: 1347–52. 14 Orringer JS, Kang S, Hamilton T, et al. Treatment of acne vulgaris with a pulsed dye laser. JAMA 2004; 291: 2834–39. 15 Childers MA, Franco W, Nelson JS, et al. Laser surgery of port wine stains using local vacuum pressure: changes in skin morphology and optical properties (Part I). Lasers Surg Med 2007; 39: 108–17. 16 Millon SR, Roldan-Perez KM, Riching KM, et al. Effect of optical clearing agents on the in vivo optical properties of squamous epithelial tissue. Lasers Surg Med 2006; 38: 920–27.
© 2007 Elsevier Ltd. All rights reserved.
There have been significant advances in the use of lasers for skin disorders. New generation pulsed dye lasers and dual wavelength lasers have optimized the treatment of vascular lesions such as port wine stains. The improved safety of lasers for hair removal has enabled children with pathologically excessive hair to be treated safely, and for treatment to be carried out on dark-skinned individuals. Exogenous melanin and radiofrequency devices have made epilation of light-coloured hair possible. The pulsed dye laser and intense pulsed light devices may improve active inflammatory acne, and can be used as optical sources for photodynamic therapy in the treatment of cutaneous dysplasias including actinic keratoses. Fractional resurfacing technology has bridged the gap between ablative resurfacing lasers and non-ablative lasers. Pneumatic suction devices may improve comfort and efficacy of treatment and are available as an attachment for existing lasers or integrated into handpieces. Keywords acne; dual wavelength lasers; fractional resurfacing; hair removal; intense pulsed light; lasers; melanin; optical clearing agents; photodynamic therapy; pneumatic suction devices; port wine stains; vascular lesions
Lasers have been used for the treatment of cutaneous disorders for over 30 years. Technological advances have led to the availability of a wide range of devices that are powerful, versatile and costeffective, enabling an increasing range of conditions to be treated safely and effectively. Lasers emit high intensity light of a single (monochromatic) wavelength, which is absorbed by target structures in the skin and converted to heat energy. This key principle underlies the interaction between light and biological tissues
and is known as the theory of selective photothermolysis (Figure 1).1 The main targets (chromophores) in the skin are oxyhaemoglobin, contained in blood, and melanin, contained in hair follicles and pigmented lesions. Other targets include tissue water and tattoo pigments. Selective heating of target structures produces clinically appreciable effects, while heating of non-target structure leads to unwanted side effects. Intense pulsed light (IPL) devices are, like lasers, sources of high-energy light.
However, IPLs are polychromatic and emit multiple wavelengths with each pulse. Filters with different cut off values tailor the wavelength range that is emitted to the cutaneous target of interest. The efficacy of IPLs can be explained by the fact that chromophores absorb light over a wide range of wavelengths, and so monochromacity is not a prerequisite for selective targeting. IPLs can, therefore, be used in some conditions that are responsive to lasers.
Advances in the treatment of existing indications Sajjad Rajpar MBChB (Hons) MRCP is a final year Specialist Registrar in Dermatology at the Birmingham Skin Centre, Sandwell and West Birmingham Hospitals NHS Trust, Birmingham, UK. His main interests are in dermatologic lasers and cutaneous oncology. Competing interests: none declared. Sean Lanigan MD FRCP DCH is a Consultant Dermatologist at City Hospital, Birmingham, UK. He is a recognized national leader in cutaneous laser therapy and has authored over 140 medical publications and the only European textbook in this field. Competing interests: Dr Lanigan is salaried Medical Director of Sk:n limited a nationwide provider of aesthetic cutaneous and laser treatments. He has received research grants, honoraria or equipment loans from the following laser manufacturers: Candela, Alma, Cynosure, Omnilux, Laserscope, Reliant, Lynton and Palomar.
MEDICINE 35:8
473
Vascular lesions The pulsed dye laser (PDL) revolutionized the treatment of port wine stains (PWS) when it was introduced 20 years ago. PWS are vascular malformations composed of ectatic dermal vessels, and affect 1 in 200 individuals. Lesions located in the area supplied by the ophthalmic division of the trigeminal nerve may be associated with leptomeningeal angiomas (Sturge-Weber syndrome). PWS can be disfiguring, cause glaucoma
© 2007 Elsevier Ltd. All rights reserved.
WHAT'S NEW
Absorption coefficient
Absorption spectra of melanin and oxyhaemoglobin, the two main target structures (chromophores) in the skin
Oxyhaemoglobin
Melanin
400
500
600
700
800
Wavelength (mm) Figure 1
and become thick and hypertrophic in adulthood. The current trend is to treat lesions during the pre-school period in order to minimize these complications. Thermal damage to blood vessels during laser treatment leads to a reduction in the number and size of blood vessels producing an observable lightening of lesions. First-generation PDLs operated at wavelengths of 577 or 585 nm, and produced significant lightening in 40% of patients. A major development has been the modification of first-generation PDLs to include longer wavelengths (595−600 nm), more power and better skin cooling. This has led to more effective clearance of PWS, including those that have been resistant to first-generation PDLs. Despite this, at least 20% of PWS fail to respond, and one-third re-darken in the 10 years after treatment.2 Strategies under investigation that may overcome these inadequacies include the use of suction devices (discussed below) and dual wavelength lasers.3 An example of the latter is the Cynergy PL (Cynosure, MA, USA), which emits a pulse at 585 nm followed by a pulse at 1064 nm. The initial pulse targets superficial vessels converting oxyhaemoglobin to methaemoglobin. The second pulse has a longer wavelength and penetrates deeper into the skin. It targets deeper blood vessels, but is also better absorbed by the recently formed methaemoglobin in superficial vessels. In combination, the dual pulses allow the delivery of more energy to vessels of varying depths,
MEDICINE 35:8
which may translate to better rates of clearance of PWS. Hair removal The leading use of lasers in the commercial sector is for hair removal. A prospective analysis of 3143 laser treatments in 373 patients conducted at our unit has demonstrated that laser-assisted hair removal with the ruby, alexandrite and Nd:YAG lasers is safe with a very low incidence of persisting side effects.4 Individuals with fair skin and darkly pigmented hair are considered the best candidates and, after a course of 6 treatments, can obtain a 60−70% reduction in hair counts at 2 years. Energy is absorbed by melanin in hair shafts and diffuses out to damage surrounding follicular structures. It is still unclear whether the cellular target is the hair follicular epithelium, stem cells in the bulge region or the dermal papillae. The development of long pulse (1064 nm) lasers has enabled the treatment of dark skinned individuals, who are prone to epidermal side effects such as blistering and dyspigmentation with traditional hair removal lasers (such as the 694 nm ruby laser). Longer wavelengths penetrate deeper into the skin, and are less likely to be competitively absorbed by melanin in the epidermis, which is abundant in darkly pigmented individuals. Improvements in cooling technologies that protect the epidermis by lowering its temperature have also facilitated safer hair removal in darker individuals. The long pulsed 474
Nd:YAG is therefore the laser of choice for hair removal in darker skin types, and also useful for pseudofolliculitis barbae which can otherwise be quite resistant to conventional treatment. In this condi tion, which predominates in AfricanCaribbean males, hair may grow back into follicles and cause inflammatory papules which frequently scar. In one study of 26 patients with dark skin types, there was a 61% reduction in papule count after one treatment with the long pulsed Nd:YAG.5 A single case report has also shown efficacy of this laser in recalcitrant folliculitis decalvans, another follicular inflammatory disorder.6 Children may suffer from localized hypertrichosis, generalized hypertrichosis and hirsutism. These conditions can lead to significant psychosocial distress. A recent retrospective case series demonstrated that laser hair removal was safe and well tolerated in children under the age of 16.7 Conventional lasers cannot treat white, grey and blond hair as the lack of melanin prevents localization of laser energy to the hair shaft. Exogenous melanin in the form of a phosphatidylcholine-based liposome solution (Meladine: Creative Technologies, USA) can be applied before laser treatment to temporarily increase follicular melanin. This permits laser removal of light coloured hairs though at a significantly greater expense. A combined radiofrequency and IPL device (Aurora SR: Syneron, Toronot, Canada) has also been shown to be effective for lightly pigmented hair, as the delivery of radiofrequency energy to hair follicles is claimed to be independent of hair colour.8
New devices and indications Fractional resurfacing The C02 and Er:YAG lasers are used for resurfacing. They target tissue water and non-specifically ablate layers of skin to varying depths. Significant improvements can be obtained with these lasers for scars (including those from acne vulgaris), birthmarks (such as congenital melanocytic naevi) and cutaneous growths (such as adenoma sebaceum of tuberous sclerosis). However, recovery can be protracted and several side effects are recognized, including dyspigmentation, scarring and prolonged
© 2007 Elsevier Ltd. All rights reserved.
WHAT'S NEW
Fractional resurfacing a
b
a There is contiguous tissue damage with conventional resurfacing lases. b There are small columns of laser injury with fractional resurfacing devices, with sparing of intervening skin. This permits a more rapid recovery.
Figure 2
erythema. A new laser technology, fractional photothermolysis, has recently been introduced to specifically overcome the drawbacks of conventional resurfacing.9 Instead of producing one beam that causes even thermal damage to tissue in its path (as with conventional resurfacing lasers), the output from fractional resurfacing devices consists of thousands of microscopic columns, which each produce thermal damage to a small volume of tissue (Figure 2).
As ablation is non-confluent, the risk of scarring is reduced and recovery is rapid, with epidermal healing taking only 24 hours by means of keratinocyte migration. Side effects last 24 to 48 hours, and consist mainly of erythema and oedema. The procedure can be performed under topical anaesthesia with slight discomfort. Although promising, this technology is still in its infancy and optimum treatment frequency and parameters remain to be defined.
Photodynamic therapy Photodynamic is used in dermatology for various disorders, including actinic keratoses and Bowen's disease (forms of in situ squamous cell carcinoma). 5-aminolaevulinate cream is applied to lesions under occlusion for 4 hours. Dysplastic cells preferentially take up the 5-aminolaevulinate where it saturates the haem biosynthesis pathway leading to an excess of intracellular protoporphyrin IX (PpIX: an endogenous photosensitizer). Conventionally, light, at a wavelength capable of activating PpIX (usually in the red spectrum), is then applied for 10 to 60 minutes. Photoactivated PpIX produces highly reactive free radicals and singlet oxygen intermediates that lead to cell death. It has recently been shown that the PDL and IPL are an effective light source for photodynamic therapy,10 with the advantage of a shorter treatment time, less pain, less post treatment erythema, faster recover and the ability to treat multiple widespread lesions at one sitting. Lesions that have been shown to improve with PDL or IPL photodynamic therapy (PDT) include actinic keratoses,11,12 viral warts, inflammatory acne, sebaceous gland hyperplasia and lichen sclerosus.
Acne vulgaris Acne vulgaris is among the commonest human dermatoses, affecting 90% of teenagers at some stage. Conventional treatment options are limited due to being
Improvement of acne vulgaris with the pulsed dye laser. Occasionally, individuals may have a good response to pulsed dye laser monotherapy for acne vulgaris, though this is unusual in our experience. Figure 3
MEDICINE 35:8
475
© 2007 Elsevier Ltd. All rights reserved.
WHAT'S NEW
ineffective, intolerable or having high non-compliance levels. There are also concerns about bacterial resistance with long-term antibiotic use. A recent study showed a significant reduction in the severity of acne after a single treatment with the PDL,13 though a subsequent splitface randomized controlled trial failed to show any effect (Figure 3).14 Lasers in the mid-infrared range, that cause dermal heating and thermal injury to sebaceous glands, have also been reported to improve active acne. This includes the 1320 nm Nd:YAG laser, the 1450 nm diode laser and the 1540 nm Erbium glass laser. Lasers are increasingly used in an adjuvant role to conventional acne treatments, although several controlled trials are underway which will help clarify their role further.
Adaptations that increase the efficacy of devices Pneumatic suction devices Pneumatic suction devices are a recent enhancement to existing lasers and IPLs. A negative pressure is applied to the skin before the pulse is delivered. This gently pulls and stretches the skin so as to thin the epidermis, reduce the density of epidermal melanin, bring the dermis closer to the light source and activate sensory fibres, thereby reducing the transmission of pain. As a result, lower energies are required, there is theoretically a lower propensity for side effects, and treatment is more comfortable. Negative pressure may also increase the volume of dermal vessels.15 Expanded vessels concentrate laser energy better as they contain more blood. Pneumatic suction devices may be integrated into the laser or IPL handpiece (e.g. Aesthera PPx, Pleasanton, CA, USA) or a separate attachment that can be
MEDICINE 35:8
used with existing systems (e.g. Inolase, Candela Corp, Boston, USA). Optical clearing agents A significant proportion of the light emitted by lasers is scattered by the epidermis.16 Non-human and laboratory data have shown that hyperosmotic chemicals such as glycerol and propylene glycol enhance penetration of light to dermal targets by reducing scattering in the epidermis. This has the potential of improving the efficacy of lasers and reducing unwanted epidermal injury. Optical clearing agents are currently impractical to use in the clinical context, and refinements in the epidermal delivery mechanism of these agents are awaited. ◆
References 1 Anderson RR, Parish JA. Selective photothermolysis: precise microsurgery by selective absorption of pulsed radiation. Science 1983; 220: 524–27. 2 Huikeshoven M, Koster PH, de Borgie CA, et al. Redarkening of port-wine stains 10 years after pulsed-dye-laser treatment. N Engl J Med 2007; 356: 1235–40. 3 Ahcan U, Zorman P, Recek D, et al. Port wine stain treatment with a dualwavelength Nd:Yag laser and cryogen spray cooling: a pilot study. Lasers Surg Med 2004; 34: 164–67. 4 Lanigan SW. Incidence of side effects after laser hair removal. J Am Acad Dermatol 2003; 49: 882–86. 5 Ross EV, Cooke LM, Overstreet KA, et al. Treatment of pseudofolliculitis barbae in very dark skin with a long pulse Nd:YAG laser. J Natl Med Assoc 2002; 94: 888–93. 6 Parlette EC, Kroeger N, Ross EV. Nd:YAG laser treatment of recalcitrant folliculitis
476
decalavans. Dermatol Surg 2004; 30: 1152–54. 7 Rajpar SF, Hague J, Abdullah A. Laser hair removal is safe and well tolerated in children. Br J Dermatol 2006; 155(suppl 1). 8 Sadick NS, Shaoul J. Hair removal using a combination of conducted radiofrequency and optical energies – an 18 month follow up. J Cosmet Laser Ther 2004; 6: 21–26. 9 Manstein D, Herron GS, Sink RK, Tanner H, Anderson RR. Fractional photothermolysis: A new concept for cutaneous remodeling using microscopic patterns of thermal injury. Lasers Surg Med 2004; 34: 426–38. 10 Brancaleon L, Moseley H. Laser and non-laser light sources for photodynamic therapy. Lasers Med Sci 2002; 17: 173–86. 11 Alexiades-Armenakas MR, Geronemus RG. Laser-mediated photodynamic therapy of actinic cheilitis. J Drugs Dermatol 2004; 3: 548–51. 12 Kim HS, Yoo JY, Cho KH, Kwon OS, Moos SE. Topical photodynamic therapy using intense pulsed light for treatment of actinic keratosis: clinical and histopathologic evaluation. Dermatol Surg 2005; 31: 33–37. 13 Seaton ED, Charakida A, Mouser PE, Grace I, Clement RM, Chu AC. Pulsed-dye laser treatment for inflammatory acne vulgaris: randomised controlled trial. Lancet 2003; 362: 1347–52. 14 Orringer JS, Kang S, Hamilton T, et al. Treatment of acne vulgaris with a pulsed dye laser. JAMA 2004; 291: 2834–39. 15 Childers MA, Franco W, Nelson JS, et al. Laser surgery of port wine stains using local vacuum pressure: changes in skin morphology and optical properties (Part I). Lasers Surg Med 2007; 39: 108–17. 16 Millon SR, Roldan-Perez KM, Riching KM, et al. Effect of optical clearing agents on the in vivo optical properties of squamous epithelial tissue. Lasers Surg Med 2006; 38: 920–27.
© 2007 Elsevier Ltd. All rights reserved.