DOI: 10.1111/j.1468-3083.2011.04406.x JEADV REVIEW ARTICLE Guielines on the safety of light-base home-use hair removal evices from the European Society for Laser Dermatology G. Town,, * C. Ash, C. Dierickx, K. Fritz, P. Bjerring, M. Haeersal Faculty of Applie Design & Engineering, University of Wales, Swansea Metropolitan University, Swansea Cyen Institute of Light Therapy, Institute of Life Sciences, Swansea University, UK Skin an Laser Center, Boom, Belgium Dermatology an Lasercenters Lanau an Kanel, University of meicine an pharmacy Carol Davila Bukarest, Romania, universities Osnabrueck, Germany an Bern, Switzerlan Department of Dermatology, Mølholm Hospital, Vejle, an Department of Dermatology, University of Copenhagen, Bispebjerg Hospital, Copenhagen, Denmark *Corresponence: G. Town. E-mail: gofreytown@mac.com Abstract In the past 5 years since their US introuction, there has been a rapi proliferation of light-base hair removal evices intene for home-use. In the last 2 years in Europe, sales alreay run into many tens of thousans of units with well-known multi-national companies entering the market. These guielines provie a efinition of light-base home-use technology, to inform healthcare professionals about home-use light-base technology an encourage manufacturers wishing to sell in Europe to aopt best practice. The review presents the current status on stanars an regulation issues an consiers home-use safety issues, encompassing human, evice an electrical safety, given risks to the eyes an skin from optical raiation both to the consumer an persons in the vicinity. Propose technical measurement methoology is consiere with focus on recognize critical parameters for the safe use of light-base hair removal technology incluing recoring the technical performance an safety claims of a range of home-use hair removal evices. The literature review emphasizes potential averse incients an safety aspects of treating cosmetic conitions, such as unwante hair growth. Although some regulations exist, they iffer from region to region an there is a specific nee for international common principles an guielines relating to the manufacture, marketing an use of intense pulse light an laser evices, incluing manufacturing stanars for home-use proucts intene, amongst others, for cosmetic hair removal an photo-rejuvenation proceures. In these guielines, the European Society for Laser Dermatology (ESLD) provies a professional view of what best practice may imply for manufacturers an consumers alike. Receive: 3 September 2011; Accepte: 29 November 2011 Conflict of interest Gofrey Town receives consultancy fees an travel grants from CyDen Lt., SA1 8PH, Swansea, UK an Unilever HPC, Trumball, USA. Caerwyn Ash receives salary from Cyen Lt., SA1 8PH, Swansea, Wales, UK. Christine Dierickx receives consultancy fees from Procter & Gamble, Cincinnati, Ohio 45202, Unite States. Klaus Fritz is remunerate for presentations an hans-on training with other evices manufacture by one of the companies mentione but not relate to this technology. Peter Bjerring has receive consultancy fees from CyDen Lt., SA1 8PH, Swansea, Wales. Merete Haeersal receives consultancy fees from Procter & Gamble, Cincinnati, Ohio 45202, Unite States. Introuction Ever since a Frenchman, Jean-Jaques Perrett, invente the first safety razor in the late eighteenth century, the race has been unerway for companies to exploit the consumer market for safe, home-use personal hair removal evices. With recent avances in technology, evice manufacturers have been expaning evicemarketing categories to inclue treatments for acne, wrinkles, cellulite, alopecia an skin rejuvenation as well as tooth bleaching an all manner of boy an poiatry treatments. Several leaing laser an intense pulse light (IPL) manufacturers have evelope low-powere, miniaturize systems to meet the nees of the omestic consumer wishing to unertake
800 Town et al. Figure 1 Home-use hair removal evices ientifie in this stuy. From top left: Tria (Tria Beauty Inc, CA, USA), Rio Scanning Laser (Dezac Lt., UK), ipulse Personal (CyDen Lt., UK), Silk n an SensEpil (HomeSkinovations, Yokneam, Israel), i-light LumaSmooth (Remington, USA), Teny Epil Flash (GHT Innovation, France), IPL 8000 (Dezac Lt., UK), E-One (E-Swin, France), Lumea (Philips, Einhoven, Netherlans) an Viss (Vissbeauty, Korea). epilation an other cosmetic treatments in the privacy of their own home an at a price cheaper than a professional service Fig. 1. This movement from professional oversight to consumer use has meant that home-use evices must be smart to minimize averse events an has given manufacturers the challenge of focusing on specific safety measures to limit the risk of acciental injury to the eyes an skin of the consumer an those in the vicinity of the user. The lack of any specific current stanars controlling require performance parameters of light-base evices for home-use has allowe a number of such proucts to be offere for sale in some international markets without reliable evience-base ata on safety an efficacy. Although home-use evices may offer greater privacy an personal convenience to the consumer than professionally elivere hair removal treatments an a reuction in the cost of maintaining hair free skin for extene perios, eucation of the consumer in light-base treatments is more ifficult than traitional methos of consumer epilation. Comprehensive eucation materials, etaile instructions for use, DVDs an consumer care support shoul be manatory as part of the comprehensive safety plan for the sale of such evices to the general public who are otherwise unaware of potential safety issues. Other consumer eucation strategies may inclue physician-irecte use of home-use evices, in-store traine sales consultants an web-base tutorials. The consumer shoul be informe of safety issues in general an specifically about the potential implications of light-inuce post-inflammatory hyperpigmentation following treatment on sun tanne skin. 1 Although professional proviers are able to accommoate a wier range of skin types an provie faster an possibly longer-lasting treatments than are attainable with home-use systems, omestic evices may still play a significant part in removing unwante boy an facial hair, stimulating hair growth, as well as rejuvenating age an photoamage skin amongst a general public unable or unwilling to pay for professional treatments. This review article focuses on home-use evices for hair removal an intens to inform healthcare professionals about home-use light-base technology an influence manufacturers an istributors wishing to sell in Europe to aopt best practice. In particular, attention is given to human safety issues an the risks to the eyes an skin from optical raiation, both to the self-treating consumer an persons in the vicinity of the user. The publishe technical performance of a range of home-use evices is inclue with iscussion of recognize critical parameters for the safe an effective use of light-base technology in hair removal. 2 Definitions of a light-base home-use evice In these guielines, the authors efine home-use light-base evicesasprouctsintenebyesignanintentionforbeauty treatments an not meical proucts for iagnosis or treatment of any isease, isorer or injury to a person or animal. The authors will consier laser an IPL evices being sol legitimately over-the-counter to en users in Europe through epartment stores, pharmacies, internet on-line stores, mail-orer catalogues an TV shopping channels for the purpose of treating unwante hair. To ate, lasers an IPL evices are the only lightbase evices shown clinically to have sufficient energy to remove hair an appear to offer a real alternative to conventional methos
Safety of light-base home-use hair removal evices 801 Table 1 Table listing manufacturers evice ata for fluence, pulse uration an wavelength, illustrating that only three manufacturers publish claime values for these three key technical parameters. Manufacturer Device CyDen ipulse Personal IPL E-Swin E-One IPL* GHT Teny Epil-Flash IPL Home Skinovations Silk n IPL Home Skinovations SensEpil IPL Philips SatinLux Lumea IPL Claime fluence (pulse energy) J cm 2 Claime pulse uration ms 7.0 10.0 25 74 530 1100 Max 12.5 Not given 575 1100 20 24 33 600 950 Not given Not given 475 1100 Not given Not given 475 1100 2 6.5 <2 >570 Remington i-light LumaSmooth IPL Not given Not given Not given Rio Dezac Not given Not given 808 Salon Scanning Laser Rio Dezac Not given Not given Not given IPL 8000 Tria Beauty 6 24 125 600 800 TRIA Laser Vissbeauty Viss IPL (23 Joules) Not given 530 930 Claime wavelength (spectral range) nm IPL, intense pulse light. *Inepenently publishe technical ata on the E-One IPL (E-Swin, France), which is a CE-marke meical evice, but sol for home use, inicates a maximum pulse energy of 72 J an shoul therefore be consiere equivalent to other professional meical evices on the market. of epilation. A total of nine currently available IPL evices an two laser evices for hair removal proceures were ientifie in this stuy Table 1. Although unwante boy an facial hair can be cause by specific meical conitions, such as hypertrichosis (excess hair at any boy site) an hirsutism (excess hair in anrogen-epenent sites in women) it can also be seconary to enocrine isorers, malnutrition, meication an virilising tumours. 3 However, these are meical conitions requiring avice an treatment from a healthcare professional an the authors believe that home-use evices shoul be consiere purely for cosmetic conitions with no unerlying meical abnormalities an exclusively for improving cosmetic appearance. From a technical stanpoint, the maximum pulse energy available from a home-use IPL is typically in the range 7.5 30 J elivere over at least 2.5 60 ms pulse uration in the spectral range 450 1200 nm an over treatment areas (spot sizes) of 2 6 cm 2. Only the E-One IPL (E-Swin, France), which is a CE-marke meical evice, but sol for home-use, excees this range with a maximum pulse energy of 72 J an shoul probably therefore be treate as equivalent to other professional meical evices on the market. Home-use hair removal lasers consiere in this review operate at a nominal 800 808 nm wavelength an one evice, the Tria laser (Tria Beauty, Dublin, CA 94568, USA) claims to eliver up to 22 J cm 2 with pulse urations up to 600 ms an a treatment area on tissue of 0.79 cm 2. Principles of photobiology Light prouces a biological effect in skin via three mechanisms of interaction between light an tissue: photochemical, photothermal an photomechanical effects. Lasers an intense pulse light sources utilize photothermal interaction in skin to achieve hair removal, where incient light at the skin surface is either reflecte (approximately 5% of photon energy is irectly reflecte) or refracte an absorbe or scattere within the layers of the epiermis an ermis (95% of photons). If light is reflecte from the surface of the skin or transmitte completely through it without absorption, there will be no effect. In orer for light to prouce any biological effect in skin it must first be absorbe, where transformation of raiative optical energy into a ifferent form of energy (usually heat) occurs by specific interaction with tissue. There are only four main components (or chromophores ) in the skin that absorb visible an near infrare light energy: melanin, haemoglobin, porphyrin an intracellular or extra-cellular water, an their absorption spectra an absorption an scattering coefficients have been well investigate. Manufacturers of light-base equipment have taken this information an esigne technological evices that prouce light, which have the correct
802 Town et al. wavelengths to be precisely absorbe by one or more of these components of skin, while minimizing collateral thermal injury to the surrouning tissue. This mechanism, calle selective photothermolysis, employs a knowlege of the rate of heat loss from specific targets, such as the melanin in hair follicles, whereby carefully selecte wavelengths, optical energy ensity an pulse uration precisely amage an absorbing biological target without causing injury to surrouning structures. 4 In the case of a terminal hair follicle, energy is absorbe by the melanin-rich hair shaft an follicular matrix, the temperature of the chromophore increases an thermally inuce biological changes take place to amage or estroy the follicle an inuce a change in normal hair cycling e.g. telogen inuction. Going from professional to home-use employsthesamemoe of action, so it is reasonable to anticipate a similar averse event profile, although the use of consierably lower energy elivery in home-use evices woul suggest a lower quantitative sie effect response in tissue. It is also possible that the typical averse event profile of high power professional systems, which coul overwhelm some potential tissue responses, may emerge in home-use proucts with greater prevalence. The thermal events associate with the moe of action therefore still rive safety concerns with this type of technology for home-use an serve as a framework for presenting the ocular an ermal hazars in these guielines. Table 2 Table listing manufacturers evice FDA pre-marketing 510(k) clearance for hair removal an CE-Mark status. Manufacturer Device CyDen ipulse Personal IPL E-Swin E-One IPL GHT Teny Epil-Flash IPL Home Skinovations Silk n IPL Home Skinovations SensEpil IPL Philips SatinLux Lumea IPL FDA 510(k) cleare Pening No No CE-mark (meical) Remington i-light LumaSmooth IPL Not known Rio Dezac Pening Salon Scanning Laser Rio Dezac Pening IPL 8000 Tria Beauty TRIA Laser Vissbeauty Viss IPL Not known IPL, intense pulse light; FDA, Foo an Drug Aministration. Stanars & regulation It is important to acknowlege the ifference between the US an European Union (EU) countries with respect to meical vs. nonmeical classification of evices for hair removal. In the US, home-use hair removal evices are treate as meical evices for premarketing permission by the Foo an Drug Aministration (FDA) for sale over-the-counter (OTC) to consumers. In the EU, such evices are treate as cosmetic proucts. It follows that ifferent regulations control the manufacture an sale of these proucts in ifferent geographical areas. In the USA, the FDA controls OTC market licencing of lightbase home-use hair removal evices an there are alreay a number of preceents Table 2. It shoul be remembere, however, that strict Premarket Approval (PMA) requirements to market a evice for consumer use an rigorous obligations in respect of applying human usability factors to optimize safety are impose on manufacturers by the FDA 5. Which laser stanars apply in the USA? The FDA has affirme its commitment to harmonize selecte provisions of the International Electrotechnical Commission (IEC) Laser Stanars in a guiance ocument issue in June 2007. For most of the worl, the applicable laser safety stanar is the international stanar set by the IEC, an known as IEC 60825 (previously IEC 825). The USA user stanar is American National Stanars Institute (ANSI) Z136.1, whereas the manufacturer s stanar is CDRH 21 Coe of Feeral Regulations (CFR) parts 1040.10 an 1040.11. Recently, FDA s Center for Devices an Raiological Health (CDRH) has ecie to accept certain conformance stanars of IEC 60825-1 an IEC 60601-2-22 stanars in lieu of those require by 21 CFR 1040.10 an 1040.11. This FDA recognition of the IEC stanars has not yet been coifie an in the interim, so as to reuce the regulatory buren on inustry an the CDRH agency, FDA has release Laser Notice No.50 that explains which of the IEC stanars will be accepte in the USA. This inustry guiance allows some IEC stanars for lasers to be accepte within the USA. Further information on CDRH requirements can be foun at http://www.fa.gov/crh/rahealth/proucts/ lasers.html. Laser manufacturers intening to istribute OTC light-base home-use hair removal evices in USA shoul consier that the FDA will treat these as meical evices an compliance will be require with IEC 60825-1 (Safety of laser proucts Part 1: Equipment classification an requirements) an IEC 60601-1-11:2010 (Meical electrical equipment Part 1 11: General requirements for basic safety an essential performance. Collateral stanar: Requirements for meical electrical equipment an meical electrical systems use in the home healthcare environment). The requirement for compliance with this latter stanar hols irrespective of whether the evice is use by a consumer or healthcare professional. Certain coifie regulations outline in 21 CFR 1040.10 an 1040.11 remain in effect an therefore strict compliance with the IEC stanars alone is not sufficient for complying with all US laser requirements.
Safety of light-base home-use hair removal evices 803 In Europe, omestic (i.e. househol) electrical appliances are normally manufacture uner national legislation to comply with stanars issue (originally) by the International Electrotechnical Commission (IEC) an subsequently ratifie by CENELEC. The IEC is the international stanars an conformity assessment boy, for all fiels of electro-technology. CENELEC is the European Committee for Electrotechnical Stanarization, base in Brussels. Which laser stanars apply in Europe? Existing IEC laser stanars control the manufacture of lasers, an these have been ratifie by CENELEC. The recently publishe stanar IEC 60601-2-57 for intense light evices (Meical electrical equipment Part 2 57: Particular requirements for the basic safety an essential performance of non-laser light source equipment intene for therapeutic, iagnostic, monitoring an cosmetic aesthetic use) was ratifie by CENELEC in April 2011. In the opinion of the authors of this present article, until a suitable, eicate stanar for home-use laser an intense light evices is evelope, the applicable parts of the following general stanars an guielines (inasmuch as they apply to home-use evices) shoul be followe by manufacturers. Strictly speaking, these stanars carry more legal weight in Europe once they are recognize as being harmonize stanars an are liste in the Official Journal of the EU enabling the manufacturer to claim presumption of conformity with the associate European Directives, e.g. Low Voltage Directive, Meical Devices Directive, etc. In short, these stanars are aopte an manatory, an currently represent the best way forwar for manufacturers of evices intene for the home-use sector: IEC 60825-1 (Safety of laser proucts Part 1: Equipment classification an requirements) In 2000, there was a major revision of the funamental International an European laser safety stanars IEC 60825-1 an EN 60825-1 (which are wor ientical) an these versions came into effect on 1st January 2001. New laser classes were introuce an Maximum Permissible Exposure (MPE) an Accessible Emission Limit (AEL) tables were change as well as revisions to measurement aperture requirements an changes to the user section an appenices. IEC 60601-1 (Meical electrical equipment Part 1: General requirements for basic safety an essential performance) This is the General Stanar containing requirements for basic safety an essential performance that are generally applicable to meical equipment an are either supplemente or moifie as Particular Requirements stanars. Where particular stanars exist, they shoul be use in conjunction with the General Stanar. IEC 60601-2-22 (Meical electrical equipment Particular requirements for basic safety an essential performance of surgical, cosmetic, therapeutic an iagnostic laser equipment) IEC 60601-2-22 applies to the safety an essential technical performance of laser equipment for either cosmetic, surgical, therapeutic, meical iagnostic or veterinary applications, intene for itsuseonhumansoranimals,classifieasaclass3borclass4 laser prouct as efine in IEC 60825-1. This eition constitutes a technical revision an takes account of the new eitions of the General Stanar IEC 60601-1 an publication IEC 60825-1. Throughout this International Stanar, light emitting ioes (LED) are inclue whenever the wor laser is use. IEC 60601-2-57 (Meical electrical equipment Part 2-57: Particular requirements for the basic safety an essential performance of non-laser light source equipment intene for therapeutic, iagnostic, monitoring an cosmetic aesthetic use) IEC 60601-2-57:2011 an EN 60601-2-57:2011 applies to basic safety an essential performance of light source equipment consisting of a single or multiple sources of optical raiation, with or without power supply in the wavelength range 200 nm to 3000 nm, with the exception of laser raiation, an intene to create non-visual photo-biological effects in humans or animals for therapeutic, iagnostic, monitoring, cosmetic aesthetic or veterinary applications. ICNIRP Guielines on exposure to broaban incoherent optical raiation. Health Physics 1997; 73:4:539 554 These guielines from the International Commission on Non- Ionizing Raiation Protection (ICNIRP) establish the basic principles of protection against visible an infrare raiation emitte by broaban, non-laser sources, incluing LEDs. They are intene for use by experts an regulatory boies who are responsible for eveloping controls, recommenations, guielines or coes of practice to protect workers an the public from the potentially averse effects of optical raiation. Review of Threshols an Recommenations for Revise Exposure Limits for Laser an Optical Raiation for Thermally Inuce Retinal Injury. Schulmeister K, Stuck BE, Lun DJ, Sliney DH. Health Physics 2011; Volume 100, Number 2:210 220. This publication reviews an makes recommenations to upate ICNIRP Guielines on exposure limits for broaban incoherent optical raiation, which will come into effect in 2012 an be aopte into IEC 62471 (Photobiological safety of lamps an lamp systems). The changes are quite relevant since exposure limits for pulse evices will increase quite significantly. IEC 60335-1 (Househol an similar electrical appliances Safety Part 1: General requirements) IEC 60335-1 eals with the safety of electrical appliances for househol an similar purposes, their rate voltage being not more than 250 V for single-phase appliances an 480 V for other appliances. Battery-operate appliances an other.c.-supplie appliances are within the scope of this stanar. Appliances not intene for normal househol use, but which nevertheless may be a source of anger to the public, such as appliances intene to be use by laymen in shops, in light inustry an on farms, are within the scope of this stanar. The above stanars inclue CE-marking an compliance with low-voltage regulations, electro-magnetic compatibility EMC requirements an the Meical Devices Directive. 6,7
804 Town et al. Non-meical consumer proucts (incluing light-base cosmetic home-use evices) are generally governe by national General Prouct Safety (GPS) regulations, which transpose EU regulations on general prouct safety into national law. 8 In the Unite Kingom for example, as long as a evice is markete for cosmetic applications an no meical claims are mae, the regulatory authorities (MHRA* an HPA )havenointerestexceptin reporte averse events. Proucts within the meaning of the regulations can best be escribe as all goos that are (or coul be) place on the market, or supplie or mae available (incluing in the course of proviing a service) to consumers for their private use an UK Department of Trae an Inustry (DTI) has overall responsibility for safety issues concerning these proucts. 9 The DTI normally exercises enforcement control through the local authorities (Environmental Health Division Traing Stanars). There are no specific requirements for home-use light-base hair removal or other cosmetic evices. Generally in Europe, in the absence of specific prouct regulations or national stanars, the GPS regulations will normally apply. Compliance by manufacturers must show engineere solutions that prevent acciental ischarge an hiner potential misuse. For this reason, home-use lasers an IPLs are provie with skin contact switches or sensors to ensure that the evice can only be activate in full occlusion on the skin surface. This has le some manufacturers of home-use lasers to claim that their evices fall into the Class I laser category an o not require the user to wear safety glasses. As an aitional safeguar, several manufacturers state in their instructions for use that the evice shoul not be use on the face (or above the chin). A proposal is uner iscussion within the international stanars boies to introuce a new optical classification category for light-base equipment, whereby although the system or evice coul cause biological ocular amage if accientally viewe irectly, with a sequence of internal safety checks prior to ischarge, the evice is consiere a lower risk to the user. This potential solution is currently being consiere by the IEC technical committee TC76 WG1 with a view to introuce a new laser Class 1C. Concern about the ocular safety of home-use IPL evices has le the IEC technical committee TC76 WG4 to consier a similar classification scheme for IPLs using skin contact switches or sensors, as the propose Class 1C for lasers. At an IEC meeting in Bali in June 2011, it was ecie to set up an IEC TC61 Working Group with suitable experts to evelop a new Part 2 stanar uner the IEC 60335 series for the safety of Beauty Care Appliances. The new stanar will buil on work alreay one by CENELEC TC61 WG5 an the current Australian *MHRA; Meicines an Healthcare proucts Regulatory Agency; a UK Government agency with responsibility for stanars of safety, quality an performance. HPA; Health Protection Agency; an inepenent UK boy that protects the health an well-being of the population. Stanar for these kins of proucts (AS NZS 3130:1995). The goal will be to come to one global IEC stanar. Propose technical measurement methoology Knowlege of the optical osimetry characteristics of a laser or an IPL evice is essential to establish a scientific basis for applications involving light tissue interaction. Previously, publishe stuies have ientifie five key measurement parameters for laser an IPL output: energy measurement (fluence), pulse uration (exposure time on tissue), spatial istribution (homogeneity on tissue), spectral output (wavelength or ban of wavelengths), an in the case of IPL evices, time-resolve spectral output. Stanarization of measurement introuces consistency into a system, lowering the risk of averse reactions from evice malfunction an improving treatment efficacy an reliability. Practical measurement methoology suitable for use with IPL an laser light sources is require to ensure quality control an to valiate manufacturers claims an the following propose methos have been publishe. 2,10,11 Energy measurement (fluence) The optical energy ensity generate by home-use evices (also calle fluence or raiant exposure) is the amount of light energy elivere per unit area an is measure in Joules cm 2. The ieal energy ensity will raise the temperature of the chromophore to a level that causes amage to the target, but oes not prouce averse sie effects, such as burns or blisters. Excessive fluence may increase the frequency an severity of sie effects an low energy may result in uner-treatment an user issatisfaction. Previous trials showe repeatable an consistent energy measurements of IPLs from Ophir power an energy meters Ophir L50 (300) IPL Absorber Hea (Ophir Optronics Lt, Jerusalem 91450, Israel) in comparison with raiometric analysis traceable to national stanars. However, the exact moel shoul be selecte with support from the power meters an absorber hea manufacturer to encompass the evice wavelength range, pulse exposure time an its energy range. Pulse uration (exposure time on tissue) Accoring to Anerson an Parrish, the measurement of pulse uration is important because the optimum pulse uration shoul be close to the thermal relaxation time (TRT) of the target chromophore 4 Numerous stuies have confirme this, proving that higher hair clearance rates occur when the pulse uration is close to, or longer than, the thermal relaxation time of the hair follicle. However, if the pulse uration is too long the heat iffuses to surrouning tissue, increasing the risk of averse sie effects; at the same time, the sie effect risk is also increase if the pulse uration is too short an the fluence too high. The uration of the ischarge laser or IPL pulse or sub-pulses can be measure using a reverse biase fibre optic photoioe etector (BPW32, 200 2000 nm) an amplifier, acting as a light-
Safety of light-base home-use hair removal evices 805 epenent switch. The pulse uration can be capture on an oscilloscope. The pulse uration can iffer consierably between IPL an laser systems from ifferent manufacturers: some use true single pulses or utilize two or more sub-pulses to exten overall pulse uration to allow intra-pulse epiermal thermal relaxation. Ieally, the pulse urations shoul be ajustable as various chromophores have iffering thermal relaxation times (TRT) an therefore the evice shoul match such times to target the correct chromophore. Spatial istribution (homogeneity on tissue) Inhomogeneity in the spatial profile of the laser or IPL output on skin, such as a hot spot in the centre, can cause over treatment of the skin centrally an or uner treatment peripherally. This may, in part, explain sie effects, such as burning, hypopigmentation, hyperpigmentation an or patchy increase hair growth, espite theevicebeingofasuitableaverageenergy.iftheregionof treatment is not uniform, then overlapping treatments are require which, as well as increasing the time taken for the proceure, can also cause burns. Traitionally, the spatial istribution of laser an IPL outputs has been assesse by reviewing the burn pattern on black laser alignment paper. Although this metho highlights major iscrepancies in the spatial profile an gives an overview of the energy istribution, it oes not quantify the results. A recent stuy by Thomas et al. has provie a new technique for measuring spatial istribution of IPL systems an such methoology can be aapte for laser an LED evices. Using a CCD camera an a phosphorescent screen to exten the pulse uration, average time frames can be analyse using Matlab moelling software where ark reference frames are also taken to minimize noise. 12 Spectral emission measurement (IPLs) The chromophores in the skin, which are important for many light-base treatments, have iniviual absorption spectra. This means that, epening on the target chromophore, certain wavelengths will be more effective in treating certain conitions than others. Therefore, each treatment type will be best suite to a particular wavelength or range of wavelengths. However, the wavelength or range use shoul take into account the absorption spectra of all chromophores, because heating a non-target chromophorecanamagetheskin.knowlegeofthespectraloutput of IPLs also provies information of emitte wavelengths, such as ultraviolet an infrare raiation, which can present immeiate an long-term health risks. With each evice, a photo-spectrometer apparatus can be set up to prouce accurate results with minimal experimental error. Using a USB spectrometer (Ocean Optics, Dunein, FL 34698, USA) the evice optical output is irecte at the spectrometer probe from a istance to avoi saturation of the apparatus. The spectrometer probe may be hel with a retort clamp fixe to a laboratory stan to ensure no movement of the probe. The spectral output can be save igitally an presente in a MICROSOFT EXCEL GRAPH for analysis. Propose minimum safety & efficacy testing It has to be assume that manufacturers an suppliers of homeuse light-base evices in Europe will comply with statutory safety requirements liste above uner Stanars & Regulation. In aition, manufacturers shoul test evices to the latest guielines an raft international stanars awaiting national ratification as these contain ocular hazar testing requirements incluing home-use evices (e.g. IEC 60601-2-57 Meical electrical equipment Part 2-57: Particular requirements for the basic safety an essential performance of non-laser light source equipment intene for therapeutic, iagnostic, monitoring an cosmetic aesthetic use publishe 31st January 2011 has been ratifie by CENELEC (an in the UK) publishe as BS EN 60601-2-57). Moreover, manufacturers an healthcare professionals shoul not rely upon clinical ata from publishe stuies using professional laser an IPL systems as the operating parameters an user regimes are quite ifferent an may prouce issimilar outcomes in terms of efficacy an averse event responses. Human safety The overall safety of a prouct is assesse having regar to the prouct s characteristics incluing electrical safety; packaging; instructions for assembly, maintenance an isposal; effects on other proucts with which it might be use; labelling 13 an other information provie for the consumer as well as categories of consumer at risk when using the prouct e.g. chilren. The focusofthishumansafetyreviewwillbeonocularanermal hazars. Risk of ocular amage The mechanisms by which light coul prouce ocular amage inclue photochemical, photomechanical an photothermal effects. The latter is the most likely event associate with near IR (laser) an IPL emissions, but photochemical effect is also possible with IPL. This review consiers the current approach to eye safety by manufacturers of home-use evices an escribes what coul occur. Several, but not all home-use laser an IPL manufacturers supply safety eyewear, but there is of course no guarantee that the consumer will use the protective spectacles if provie. Currently, while there are stanars for manufacturers to follow in proviing suitable protective goggles or glasses for ifferent laser classes, there is no international safety eyewear stanar for IPL evices. Most professional IPL manufacturers supply optical ensity (OD) 3, 4 or 5 safety eyewear accoring to the harmonize American an European weling eyewear stanars (EN 166 EN 169 Optical Class I, Directive for Personal Protective Equipment (PPE), 89 686 EEC). However, in the absence of any internation-
806 Town et al. ally ratifie stanars for intense light safety eyewear, suppliers may elect to follow the specific British national stanar BS 8497-2 Eyewear for protection against intense light sources use on humans an animals for cosmetic an meical applications, publishe in 2008. 14 If someone is treating their face or unerarm an fires a homeuse laser or IPL close to or irectly into the eye either because of a faulty safety switch or because the safety mechanism is efeate accientally or intentionally, what are the effects to the eye? Are they permanent or reversible? Retina, cornea & lens The human eye is a critical organ with only the blink reflex to provie limite protection against excess light exposure of elicate optical tissues incluing the highly vascularise retina, cornea, lens an pigmente iris. In the case of non-cosmetic omestic laser proucts that prouce parallel light in the wavelength range 400 1400 nm (visible to near infrare), even a laser pointer with an output greater than 5 mw has the potential to prouce permanent retinal amage because of the risk of such laser energy being focuse by the cornea an the lens to a small point on the retina i.e. low-power concentrate into a small area equates to a high power ensity an probable thermal amage to the highly pigmente an vascularise retinal tissues. Retinal injury may inclue a peripheral blin spot to partial or even total blinness. Above 1400 nm, laser exposure to the eye may cause a corneal burn whereas wavelengths above 750 nm an below 400 nm can cause lens cataracts an photochemical amage to the cornea. The light from an IPL, however, is highly ivergent an therefore cannot be focuse by the lens in the eye to a small point on the retinal epithelium. The filtere IPL output shoul not inclue any ultra-violet (UV) light, which is a primary source of eye amage through prolonge exposure. UV light causes breakown of the DNA over time resulting in cataracts an permanent amage to the cornea an lens. The amount of light in the region 400 550 nm (blue green light) prouce by most home-use IPLs is minimal, only a relatively small percentage of the filtere IPL output is below 550 nm an usually none below 500 nm. Uner normal ambient conitions, this blue green region of the spectrum may be transmitte to the back of the eye an absorbe by the retinal pigments, this absorption leas to a temperature rise in the retina an has the highest probability to inuce permanent ocular amage. There is potential for blue light hazar to the retina, particularly at shorter wavelengths between 400 nm an 500 nm an longer wavelength infrare hazar to the cornea an lens in lasers an IPLs proucing wavelengths in this higher wavelength region of the spectrum. Most home-use IPLs o not inclue any water filter that woul reuce emissions from a xenon flash lamp at higher wavelengths above 900 nm so IPL manufacturers shoul measure irraiance an calculate exposure limit values (ELVs) to ensure that publishe safety threshols are not exceee. In the absence of any specific international IPL stanars, Eaie et al., teste the ipulse Personal IPL (CyDen Lt, Swansea, UK) forocularhazar, 15 in accorance with IEC TR 60825-9 an the International Committee on Non-Ionizing Raiation Protection (ICNIRP) Guielines on Limits of Exposure to Broa-ban Incoherent Optical Raiation. 16 The conclusions of this testing showe that the evice was within the prescribe international limits for ocular exposure. Data reporte in a stuy by Ash an Town measure three popular home-use IPL evices, one of which generate emissions at the two highest settings of the evice which exceee the MPE threshol for retinal thermal hazar as set own in the current ICNIRP guielines on exposure to broaban incoherent optical raiation. 17 However, it shoul be note that this hazar coul only occur in the event that the skin contact safety mechanism faile or was accientally or intentionally efeate. Iris The iris, like the retina is rich in melanin an contains small amounts of haemoglobin an absorbs incient light, which in the case of a narrow beam laser or highly ivergent IPL may cause amage to the iris sphincter muscle use to control the amount of light hitting the retina. If this muscle is partially amage then ocular hypertension, a long-term conition that can cause visual istortion (glaucoma) an migraine, may occur. The egree of thermal absorption that may occur (assuming the eye is open an unprotecte by the skin of the eyeli) is epenent upon the amount of melanin pigment (chromophore) available in the iris as the cornea an anterior chamber are essentially clear an refracte light will pass through with only a minimal loss of energy. However, the iris acts not only as an optical filter but it also acts as a very efficient iffuser of the light beam. Pigment layers in the iris ilator muscle (raial sphincter muscle) are foun primarily in the posterior layer (closest to the lens of the eye). For light to be absorbe in these layers, the light first has to pass through the thin eyeli skin, the cornea, anterior chamber of the eye an the anterior surface of the iris muscle. The natural blink reflex alone (about ¼ secon) will not shiel the unprotecte eye from an IPL flash or laser beam, as the pulse uration is shorter than the blink reflex an the spectral range an energy elivere within the flash lamp or laser pulse may be sufficient to cause an injury. Although no cases of eye injury have been reporte following home-use laser or IPL treatments, several cases of iris amage following professional IPL treatments have been recore in the literature. 18,19 In one of these few reporte cases in the reviewe literature of iris injury following professional IPL treatment, Sutter an Lanau escribe an ocular injury to the iris of a 2-year-ol patient treate for a facial port wine stain using a high-powere meical IPL system with a 550 1000 nm filter, which elivere 14 000 Watts of pulse power using a free-ischarge pulse i.e. with a very high peak
Safety of light-base home-use hair removal evices 807 of photon energy, where the IPL use elivere 70 J of pulse energy over 5 ms pulse uration. 20 As these are rare recore cases showing ocular injury an the use of IPL technology is so wiely use, it can be conclue that the incience of ocumente professional IPL ocular injury is very low. Although the home-use evices escribe in these guielines typically employ pulse power at least five times less than the high-power IPL systems in the above reports, the possibility of ocular injury in the home-use setting still remains. Even taking into consieration that the IPL is a highly ivergent light source, the risk to the pigmente iris of the eye remains in the event of a home-use IPL evice being ischarge close to the eye with the safety mechanism impaire or efeate. Unless a light-base evice manufacturer can emonstrate compliance with current stanars specifying exempt group status for ocular hazar, protective eyewear is essential to prevent ocular amage. More case reports of iris injury by lasers using high fluence an short pulse uration following professional cosmetic eyebrow hair removal treatments have been recore in the literature. 21 26 Averse events have inclue anterior uveitis, pupillary istortion, posterior synechiae, iris atrophy, nuclear cataract, visual fiel efect, macular hole an retinal scarring. Chi-Chung Lin et al. (2010) observe that Caucasians with green-blue iris colour were more prone to iris injury in the event of laser exposure owing to the increase possibility of absorbe light energy at the anterior borer layer an more prominent trabeculae than those with a brown iris. To avoi the risk of permanent amage to the retina, lens or cornea of the human eye through acciental or intentional misuse of home-use evices, manufacturers shoul test their evices to all available stanars an guielines, an implement them even where they have not been ratifie an aopte into national law. Longer-term, manufacturers shoul collaborate with IEC working groups to create a new stanar for home-use evices, which will, amongst other important parameters, efine energy output, pulse characteristics, wavelengths an the requirement for safety sensors. Risk of skin amage vs efficacy It is well establishe in the literature that sie effects, ranging from iscomfort an pain, transient erythema an hyperpigmentation to blisters, burns an scars, can occur in the professional elivery of effective laser an IPL hair reuction an other cutaneous treatments, where operators shoul have receive training an for the most part are qualifie healthcare professionals. 27 30 It is therefore to be expecte that home-use evices that eliver positive treatment results using selective photothermolysis are also inherently likely to prouce some averse incients. In respect of light-base hair reuction an extene hair regrowth elay, threshol values for efficacy have been presente by Manstein et al. 31 an several early stuies have been publishe in peer-reviewe journals reporting positively on extene hair growth elay using home-use or simulate home-use treatments. In these stuies, mean terminal hair reuction at 6 months after as few as three sequential weekly or bi-weekly treatments was >40%. 32 37 In these simulate home-use hair removal clinical trials mil to moerate transient erythema was the most consistently reporte averse effect followe by varying levels of iscomfort or pain, ranging from a feeling of warmth to slight to moerate pain. However,inonestuy,wheretheevicewasuseonasubgroup of unsuitable skin types, Wheelan reporte that the incience an severity of averse effects increase significantly. 38 As with any treatment using a evice or chemical compoun, there are sie or averse effects; the issue is the incience an severity of these effects. Given the lower energy prouce by lightbase home-use hair removal evices compare with professional high-power systems, such sie effects following correct use shoul be less severe than with professional evices although the incience of sie effects is likely to be more pronounce in arker Fitzpatrick skin types. Even if a home-use evice is use correctly, but especially if it is use on wrong settings, if it is use excessively or the user oes not follow pre- or post-treatment instructions, the following are possible an may be referre to a general meical practitioner or ermatologist: Temporary sie effects Temporary sie effects, such as soreness, eema, reness or irritation, which can be ealt with by appropriate patient avice an meication if inicate. Hyperpigmentation is usually transient, but further self-treatment shoul be eferre an the user avise to check correct evice settings for their skin type before any further home treatments. If the evice oes not offer ifferent treatment settings an there is no other obvious cause of the averse reaction (such as irect sun exposure pre- or post-use, which coul have irritate the skin) look for other causes of the reaction, such as spray tan use, concomitant use of other epilatory methos that may have irritate the skin area treate an use of photosensitive rugs or herbal remeies (e.g. St. John s Wort). The user shoul also consier returning the evice to the supplier for fault inspection. Crusting suitable healing ointments shoul be recommene if this occurs. Mil to moerate pruritus this will normally settle over 1 3 ays, but may require meication to relieve the itching. Skin pigment changes both hyperpigmentation an hypopigmentation are possible, however, this shoul be temporary, but may take weeks or months to resolve completely. Leukotrichia or vellus change temporary or long-term bleaching of melanin from hair follicles has been reporte
808 Town et al. in the literature, where previously brown or black terminal hair changes colour to yellow or white. This rare sie effect is normally associate with use of professional highenergy evices where the effect was temporary, normal hair colour returning in 1 4 months. 39,40 Herpes simplex activation suitable meication shoul be prescribe. If the user has ha any averse sie effects from self-treatment this shoul be iscusse an an assessment mae of whether this was ue to the treatment or subsequent activities. At some stage after a course of home treatments, either if there has been less improvement of the conition than expecte by the home-use evice user or because no further clearing is likely to occur with aitional treatments, leaing them to seek meical avice, the user shoul be avise accoringly an a professional treatment recommene if appropriate. Paraoxical hair growth In some patients, optical hair removal treatment has a paraoxical effect of stimulating hair growth: new terminal hair growth has been observe in areas untreate, but in close proximity to the treate ones. The incience of paraoxical hair growth, usually associate with polycystic ovarian synrome (PCOS) an ovarian hyperanrogenism, in professional treatments has been reporte to range from 0.6% to 10%. Although liste as a contrainication by several home-use evice manufacturers, it is likely that PCOS sufferers will seek relief from unwante boy an facial hair by using light-base consumer evices leaing to activation of ormant hair follicles in untreate areas close to hirsute-treate areas. 41 Such users may seek professional meical avice or further professional treatments. The most susceptible patients are female iniviuals with arker skin types (III VI) an receiving facial treatments. In most cases, this paraoxical hair growth occurs at a site that has a high vellus count an is relatively free of terminal hairs, such as ajacent to untreate facial areas or neck. All laser an light sources have the potential to cause hair inuction, as there has been no clear relationship establishe between the types of hair removal evice or the fluence use an the incience of paraoxical hair growth.possiblecausesincluetheeffectofinflammatorymeiators an sub-therapeutic thermal injury causing inuction of the hair cycle. In two case reports, hair growth has also been reporte to occur after professional IPL treatment for removal of a port wine stain an a tattoo: terminal hair, not present before treatment, evelope in treate areas of both inications. 42 47 Base on clinical experience, it is recommene in this subset of users not to start laser treatment to prevent paraoxical hair growth or in cases where it occurs, to stop further laser treatment an revert to traitional hair removal methos, such as waxing. Hair removal an pigmente skin lesions Exposure of melanin-containing skin lesions, especially congenital melanocytic nevi an ysplastic nevi to laser an IPL, shoul be avoie because of the risk of burn an potential scarring. Moreover, there has been a report of the appearance of clinically atypical nevi when nevus cells were treate in areas previously treate for hair removal. This shoul be kept in min, especially in patients with a history of ysplastic nevi or with a personal or family history of malignant melanoma. 48 It is therefore avisable to avoi treating skin for hair removal when melanocytic nevi are present in this area. Hair removal an tattoos Toay, more than 10% of the Western population has at least one tattoo. It is therefore conceivable that permanent hair removal is esire at the location of a tattoo. However, this poses a problem when the subject has no intention of removing or altering existing tattoos, but requires hair removal on the area in question. The concern is two-fol: (i) optical treatment of a tattoo might result in faing of the tattoo an (ii) absorption of the photons by tattoo ink coul reuce the efficacy of hair removal an or cause averse effects of burning, pigment changes or scarring because of the inappropriate use of laser or IPL parameters, such as insufficiently short pulse uration (millisecons). It is therefore avisable to avoi treating skin for hair removal when a tattoo is present in this area. 49 51 Hair removal an pregnancy Laser an IPL hair removal targets ark pigment in the hair an causes thermal an or mechanical amage to the hair follicle. There are no stuies that evaluate the safety of laser or IPL hair removal uring pregnancy. There is no evience or technical rationale that treatment woul have any effect on fetal evelopment or pregnancy. Hair removal an sun exposure Patients seeking avice shoul be instructe to avoi sun-exposure before their laser or IPL treatment an to use a broa-spectrum (UVA UVB) sunscreen with SPF 15 or greater after laser or IPL treatments. 52 Hair removal an compromise skin Common sense shoul apply when using laser or other light-base evices for hair removal on compromise or amage skin. However, users shoul be tol that treatment with home-use lasers or IPLs shoul be avoie till healing of the amage or compromise skin has occurre. Hair removal an rug intake The vast majority of pharmaceuticals that have the ability to evelop abnormally heightene sensitivity to sunlight of the eyes