United States Patent [19]

Anderson et al.

,••• 11111111110 1.1 11.111 IIIIIIIU 1111II11US005735844A

Patent Number:Date of Patent:

[11]

[45]

5,735,844Apr. 7, 1998

[54] HAIR REMOVAL USING OPTICAL PULSES

[75] Inventors: R. Rox Anderson, Lexington; MelanieGrossman, Boston; William Farinelli,Danvers, all of Mass.

[73] Assignee: The General Hospital Corporation,Boston, Mass.

[21] Appl. No.: 593,565

[22] Filed: Jan. 30, 1996

Related U.S. Application Data

[63] Continuation-in-part of Ser. No. 382,122, Feb. 1, 1995, Pat.No. 5,595,568.

[51] Int. CI.6 •••••••••••••••••••••••••••••••••••••••••••••••••••••••A61N 5/06[52] U.S. CI. 60619[58] Field of Search 606/8, 9, 10, 11,

606/12, 13, 15,16, 17,36,43,44

[56]

3,538,9193,693,6233,834,3913,900,0344,388,9244,461,2944,608,9784,617,9264,819,6695,000,7525,057,1045,059,1925,182,8575,226,9075,282,7975,344,4185,425,728

References Cited

U.S. PATENI' DOCUMENTS

1111970 Meyer 128/3989/1972 Harte et aI ..9/1974 Block.8/1975 Katz et aI. 128/3956/1983 Weissman et aI ..7/1984 Baron.9/1986 Rohr.

10/1986 Sutton.4/1989 Politzer flJ6/9 X3/1991 Hoskin et aI. flJ6/9

10/1991 Chess flJ6/910/1991 Zaias flJ6I92/1993 Simon flJ6l9 X7/1993 Tankovich flJ6I1332/1994 Chess .;........................................ flJ9/9911994 Ghaffari ••......••••••••••••••••..............flJ9/9611995 Tankovich flJ6/9

FOREIGN PATENr DOCUMENTS

2 59 902 611987 France.WO 0142

671 9/1984 WIPO.

WO 86/02783 9/1986 WIPO.9515725 611995 WlPO A61B 17141

OTHER PUBliCATIONS

Anderson, R. R. and J. A. Parrish, M.D., "Selective Photo-thermolysis: Precise Microsurgery by Selective Absorptionof Pulsed Radiation," Science, 220:524-527, 1983.Anderson, R. R. and J. A. Parrish, M.D., 'The Optics ofHuman Skin." The JourtUll of Investigative Dermatology,77(1):13-19, 1981.Dover J. S., et al., "Pigmented Guinea Pig Skin IrradiatedWith Q-Switched Ruby Laser Pulses." Arch Dermatol,125:43-49, 1989.Goldman, L., Biomedical Aspects of the Laser. New York,Springer-Verlag, 1967, pp. ill-H, 220-232.Goldman, L., "Dermatologic Manifestation of Laser Radia-tion." FedAm Soc ExpBiology, Suppl. 14:S-92-8-93, 1965.Goldman, L., "Effects of New Laser Systems on the Skin."Arch Dermatol, 108:385-390, 1973.

(List continued on next page.)

Primary EXaminer-Jennifer BahrAssistant Examiner-Sonya Harris-OguguaAttorney, Agent, or Firm-Wolf, Greenfield & Sacks, P.e.

[57] ABSTRACT

A method and apparatus for simultaneously effecting theremoval of multiple hairs from a skin region by using lightenergy to destroy hair follicles in the region. Light energy isapplied to the region through an applicator which convergesthe light energy to enhance destruction of desired portions ofthe follicles, is preferably pressed against the skin region todeform the upper layers of the skin reducing the distancefrom the skin surface to portions of hair follicles which areto be destroyed, including the bulge and papilla of thefollicles, and which applicator is preferably cooled to mini-mize or eliminate thermal damage to the epidermis in theregion being irradiated. Parameters for the irradiation,including pulse duration, are selected to effect completedamage of desired portions of the hair follicles in the regionwith minimal damage to surrounding tissue and to thepatient's epidermis.

32 Claims, 8 Drawing Sheets

56

58

\.20

5,735,844Page 2

OTHER PUBLIC~ONS

Goldman, L., "Laser Surgery for Skin Cancer." NY State JMed, 77:1897-1900, 1977.Goldman, L., "Surgery by Laser for Malignant Melanoma."J. Dennatol. Surg. Oncol., 5(2):141-144, 1979.Goldman, L., 'The Skin." Arch Environ Health,18:434-326, 1969.Goldman, L. and D. F. Richfield, 'The Effect of RepeatedExposures to Laser Beams." Acta Denn.-Veneoral,44:264-268, 1964.Goldman, L. and J. Rockwell, "Laser Action at the CellularLevel." JAMA, 198:641-M4, 1%6.Goldman, L. and R. G. Wilson, ''Treatment of Basal CellF,pithelioma by Laser Radiation." JAMA, 189:773-775,1964.Goldman, L., et al., ''Biomedical Aspects of Lasers." JAMA,188:302-306, 1964.Goldman, L., et al., ''Effect of the Laser Beam on the Skin."The Journal of Investigative Dennatology, 40:121-122,1%3.Goldman, L., et al., ''Effect of the Laser Beam on the Skin.m. Exposure of Cytological Preparations." The Journal ofInvestigative Dennatology, 42:247-251, 1964.Goldman, L., et aI., ''Impact of the Laser on Nevi andMelanomas." Arch Dermatol, 90:71-75, 1964.Goldman, L., et al., "Laser Treatment of Tattoos." JAMA,210:163-166, 1967.Goldman, L., et al., "Long-Term Laser Exposure of a SenileFreckle." Arch Environ Health, 22:401-403, 1971.Goldman, L., et al., "Pathology of the Effect of the LaserBeam on the Skin." Nature, 197:912-914, 1963.Goldman, L., et al., "Preliminary Investigation of fat Emb0-lization from Pulsed Ruby Laser Impacts of Bone." Nature,221:361-363, 1969.Goldman, L., et al., "Radiation from a Q-Switched RubyLaser. Effect of Repeated Impacts of Power Output of 10Megawatts on a Tattoo of Man." The Journal of Investiga-tive Dermatology, 44:69-71, 1965.Goldman, L., et al., "Replica Microscopy and ScanningElectron Microscopy of Laser Impacts on the Skin." TheJournal of Investigative Dermatology, 52:18-24, 1969.Grossman, M. C., et al., "Damage to Hair Follicles byNormal-mode Ruby Laser Pulses." Journal of the AmericanAcademy of Dermatology, 35(6):889-894, 1996.Grossman, M. C., et al., "Laser Targeted Hair Follicles."Lasers Med Surg., Suppl. 7:221, 1995.Margolis, R. J., et aI., ''Visible Action Spectrum for Mela-nin-Specific Selective Photothermolysis." Lasers in Surgeryand Medicine, 9:389-397, 1989.

Parrish, J. A., M.D., et al., "Selective Thermal Effects withPulsed Irradiation from Lasers: From Organ to Organelle."The Journal of Investigative Dennatology, 80:75s-80s,1983.Polla, L. L., et al., "Melanosomes Are a Primary Target ofQ-Switched Ruby Laser Irradiation in Guinea Pig Skin."The Journal of Investigative Dennatology, 89:281-286,1987.Riggle, G., et al., "Laser Effects on Normal and TumorTissue." Laser Applications in Medicine and Biology,1:35--63, 1971.Shimbashi, T. and T. Kojima,''Ruby Laser Treatment ofPigmented Skin Lesions." Aesthetic Plastic Surgery,19:225-229, 1995.Taylor, C. R., et aI., ''Treatment of Tattoos by Q-SwitchedRuby Laser." Arch Dennatol, 126:893-899, 1990.Watanabe, S., et aI., "Comparative Studies of Femtosecondto Microsecond Laser Pulses on Selective Pigmented CellInjury in Skin." Photochemistry and Photobiology,53:757-762, 1991.Watanabe, S., et al., 'The Effect of Pulse Duration nonSelective Pigmented Cell Injury by Dye Lasers." The Jour-nal of Investigative Dennatology, 88:523, 1987.Welch, A. J., et al., "Evaluation of Cooling Techniques forthe Protection of the Epidermis during ND-YAG LaserIrradiation of the Skin." Neodymium--YAG Laser in Medi-cine and Surgery. New York, Elsevier, 1983, pp. 196-204.Yules, R. B., et al., 'The Effect of Q-Switched Ruby LaserRadiation on Dermal Tattoo Pigment in Man." Arch Surg,95:179-180, 1967.Zeitler, E. and M. L. Wolbarsht, ''Laser Characteristics thatMight be Useful in Biology." Laser Applications in Medi-cine and Biology, 1:1-16, 1971.Bartley et al., "An Experimental Study to Compare Methodsof Eyelash Ablation," Ophthalmology 94:1286-1289 1987.Finkelstein et al., "Epilation of Hair-Bearing Urethral GraftsUsing the Neodymium:YAG Surgical Laser" J. Of Urology,146:840-842, 1991.Gossman et al., ''Prospective Evaluation of the Argon Laserin the Treatment of Trichiasis", Opthalmic Surgery,23:183-187,1992.Gossman et al., Experimental Comparison of Laser andCryoSurgical Cilia Destruction:, Ophthalmic Surgery Sur-gery, 23:179-182, 1992.

KurilofI et al., "Pharyngoesophageal Hair Growth: The Roleof Laser Epilation", Case Reports, 98:342-345 1988.

u.s. Patent Apr. 7, 1998 Sheet 1 of 8 5,735,844

19

30

FIG. I

u.s. Patent Apr. 7, 1998 Sheet 2 of 8

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u.s. Patent Apr. 7, 1998 Sheet 5 of 8 5,735,844

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u.s. Patent Apr. 7, 1998 Sheet 8 of 8 5,735,844

46

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112

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FIG. lOB

5,735,8441

HAIR REMOVAL USING OPTICAL PULSES

This is a continuation-in-part of application Ser. No.08/382,122, filed Feb. 1, 1995 now U.S. Pat. No. 5,595,568.

This invention was made with Government support 5

under Contract NOOOI4-91-C-0084awarded by the Depart-ment of the Navy. The Government has certain rights in theinvention.

BACKGROUND

This invention relates to methods and apparatus for hair-removal using optical radiation.

Excess hair (hypertrichosis) and/or unwanted hair arecommon dermatological and cosmetic problems, and can be

15caused by heredity, malignancy, or endocrinologic diseases,for example hirsutism (i.e., excess hair due to hormonessuch as androgens). Hair can be temporarily removed usinga number of techniques including wax epilation, depilatorycreams, and, of course, shaving. Alternatively, hair can bemore permanently removed using electrolysis; this process 20involves insertion of a current-carrying needle into each hairfollicle, and is often painful, inefficient, and time consum-ing.

Optical-based methods, such as the use of laser light, have 25

also been used for hair removal. U.S. Pat. No. 4,388,924, forexample, describes irradiation of individual hair folliclesusing a laser; in this method, heating of the hair's rootsection causes coagulation in local blood vessels, resultingin destruction of the follicle and thus in removal of the hair. 30Related techniques, such as those described in U.S. Pat No.5,226,907, involve destruction of the follicle by first apply-ing a light-absorbing substance to the region of interest, thelight-absorbing substance migrating at least part-way intothe follicle, removing the excess light-absorbing substance, 35and then irradiating the region to heat the substance and thusthe follicle to cause destruction of the follicle.

The above prior art techniques suffer from a number oflimitations. First, techniques for irradiating an individualhair follicle are time consuming and therefore are generally 40not practical for removing hairs other than from a very smallregion or from a region having few hairs situated therein.The procedure can also be painful, particularly if a needle-like element is inserted into the hair follicle to facilitate lightenergy reaching the bulge and the root or papilla, parts of the 45hair follicle which must be destroyed in order to preventregrowth of the hair. Where the irradiation source is not .inserted into the follicle, it is difficult to get sufficient energyto the required portions of the follicle to result in destructionthereof without also causing significant damage to the 50

surrounding tissue and thus causing pain and injury to thepatient

While the technique of the latter patent is advantageous inthat it permits a number of hairs in a given region to besimultaneously removed, it is difficult with this technique to 55get the light-absorbing substance or chromophore deepenough into the follicle to effect destruction of the papillaFurther, this technique results in substantial energy beingapplied to and absorbed by the epidermis and other skinlayers in the region being treated, with significantly reduced 60

energy reaching the root or papilla of the follicle. Totaldestruction of the follicle, and therefore permanent, or atleast long term, hairtemoval is therefore difficult to achieve,particularly without risking damage to the epidermis andother layers of skin within the region.

A need therefore exists for an improved technique forperforming hair removal which facilitates optical energy

2reaching the bulge and base, or root of hair follicles in aregion while minimizing damage to the epidermis in theregion, thereby minimizing patient discomfort and potentialadverse side effects from the treatment

SUMMARY OF THE INVENTIONIn accordance with the above, this invention provides a

method and apparatus for the simultaneous removal of aplurality of hairs from a skin region, each of which hairs isin a follicle extending into the skin from the skin surface.

10 The technique involves placing an applicator in contact withthe skin surface in the skin region and applying opticalradiation of a selected wavelength and of a selected fluxthrough the applicator to the skin region for a predeterminedtime interval. The applicator is preferably pressed againstthe skin surface, thereby reducing the distance from theapplicator to the papilla of the hair follicles and facilitatingdestruction thereof. Further, the invention also involvescooling the skin surface in the skin region to a selected depthduring the applying of optical radiation to the skin regionand/or prior thereto. This allows the papilla of the hairfollicles to be significantly heated without damage to theskin surface in the skin region up to the selected depth.

For preferred embodiments, the applicator is utilized tocool the skin surface in the skin region to the selected depthand the selected depth is preferably at least equal to thedepth of the epidermis layer of the skin (i.e. the layer of theskin closest to the skin surface). The cooling by the appli-cator may for example be accomplished by cooling at leastthe surface of the applicator in contact with the skin surface,such cooling preferably being accomplished both before andduring the irradiation of the skin. For preferredembodiments, the cooling of the applicator is accomplishedby passing a cooling fluid through the applicator. Further, itis also preferred that irradiation of the skin surface not beperformed until the skin region has been cooled to substan-tially the selected depth. For the most preferredembodiment, cooling is performed both before and duringirradiation, and the selected flux and predetermined expo-sure time (i.e., time interval for irradiation) are selected suchthat there is at most minimal heating of skin in the skinregion to the selected depth, while there is sufficient heatingof hairs and follicles below the selected depth to at leastdamage the hairs and follicles without causing significantdamage to tissue surrounding the follicles. A preferred timeinterval for irradiation is 2 to 100 ms. The applicator is alsopreferably designed to converge optical radiation applied tothe skin region, thereby further facilitating irradiation of thefollicle papillas. For preferred embodiments, the applicatoralso has a convex surface in contact with the skin surface,applying substantially uniform pressure thereto to deformthe underlying skin surface. For alternative embodiments,the applicator is designed to form a fold of the skin in theskin region and to apply optical radiation to two substan-tially opposite sides of the fold. For example, the applicatormay have a slot formed in the surface thereof in contact withthe skin surface, with at least a portion of the skin regionbeing drawn up into the slot and optical radiation beingapplied to the skin region from at least two opposite sides ofthe slot.

It is also desirable that a substantial refractive indexmatch be maintained between the applicator and the skinsurface in said skin region. Such refractive index match maybe provided by a layer of refractive index matching sub-stance between the applicator and the skin surface in a skinregion and/or by forming the applicator of a material which

65 at least for the surface in contact with the skin region has arefractive index which substantially matches that of the skinsurface.

3To facilitate hair removal, hairs in the skin region may be

shaved prior to irradiation. However, it may be preferable toepilate the hairs in the skin region before irradiation. Whenhairs are epilated, destruction of the follicles can be facili-tated by filling the follicles from which the hairs have been 5epilated with a substance which preferentially absorbs opti-cal radiation at the selected wavelength being used forirradiation (i.e. a chromophore). Further, where only tem-porary hair removal is desired, this may be accomplished fora period of up to several weeks, relatively painlessly, by 10applying the chromophore to the area, which has beenpreferably pre-shaved, which chromophore migrates into thehair follicles to a depth of a few millimeters, roughly to thedepth of the sebaceous gland. Low level irradiation appliedthrough the applicator to the skin region will then result in 15

the destruction of the hair without destroying the follicle.An applicator suitable for use in practicing hair removal

in accordance with the above may include an inlet throughwhich optical radiation is applied to the applicator, a surfaceshaped to contact the skin surface in the skin region, an 20

optical path from the inlet to the surface, which path issubstantially transparent to optical radiation at the selectedwavelength, an element in the optical path for convergingthe optical radiation as it leaves the applicator through thesurface and some means for cooling the surface to a tem- 25

perature below that of the skin region. As indicatedpreviously, the surface is preferably formed of a materialhaving a refractive index which substantially matches, butwhich is not less than, the refractive index of the skin surfacein the skin region. For preferred embodiments, the element 30for converging the optical radiation is a lens and the meansfor cooling is a channel near the surface through whichcooling water is passed. For one embodiment, the surface ofthe applicator in contact with the skin has a convex shapewhile for an alternative embodiment the surface has a slot 35

formed therein, with the optical path leading to at least twoopposite sides of the slot, and the applicator includes ameans for drawing at least a portion of the skin region intothe slot, this means for drawing preferably includes avacuum applying element.

The foregoing and other objects, features and advantagesof the invention will be apparent from the following moreparticular description of preferred embodiments of theinvention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a perspective view of a laser-based hair-removal

device according to the invention;FIGS. 2A and 2B are cross-sectional views of an irradi-

ating unit or applicator suitable for use with a hair-removaldevice of this invention, the applicator receiving,respectively, light from a fiber optic or fiber optic bundle,and from a mirror assembly;

FIGS. 3A, 3B, and 3C are, respectively, an expanded,cross-sectional view of the contact device of the irradiatingunit in direct contact with a hair-containing skin region, across-sectional, cut-out view showing the back-scatteredoptical fields at the contact device/epidermis interfacialregion, and a cross-sectional cut-out view showing thermaltransport at the interfacial region;

FIG. 4 is a plot showing the optical absOJ:ptionspectra ofmelanin. hemoglobin, oxygenated hemoglobin, and water;

FIGS. SA and 5B show, respectively, the time and spatialprofiles and the preferred optical field used during thehair-removal process;

FIG. 6 is a plot of the computer-generated optical inten-sity as a function of skin depth for different optical fields;

5,735,8444

FIG. 7 is a photograph showing skin regions of a patientthree months after being treated according to the hairremoval method of the invention;

FIGS 8A, 8B and 8C are oscilloscope traces showing,following irradiation, the time-dependent temperatureresponses of, respectively, dry black hair, wet black hair, andlive skin surrounding the black hair sample;

FIG. 9 is a plot showing the temperature rise as a functionof laser pulse energy for dry hair (DH), wet hair (WH), andskin (S) samples of eight different patients;

FIG. 10Ais a partial cross-sectional view of the applicatorof the invention being used to practice an alternativeembodiment of the invention wherein epilation and filling ofempty follicles with a chromophore performed before irra-diation; and

FIG. lOB is a cross-sectional view of an applicator for analternative embodiment being used for hair removal.

DErAILED DESCRIPITONReferring to FIG. 1, an exemplary laser-based hair-

removal system 10 includes a light source 12, which may,for example, include one or more lasers for generating theirradiating field. The light source 12 may be opticallycoupled to a series of beam-manipulating optics 14 which,in turn, may be coupled via a fiber optic cable 16 (or otherfiber optic device) to the irradiating unit or applicator 18.During the hair-removal therapy, the light source is poweredby a voltage and current supply 19, and delivers a beam oflight through the optics 14 and fiber optics 16 to theirradiating unit or applicator 18. The field is then deliveredto a region 20 of a patient 22 (positioned, for example, on atable 25, a chair, or other suitable positioning elementdepending on the location of the region 20 on the patient'sbody) resulting in hair removal from the region 20. Once thedesired region is treated, the irradiating unit can be easilymoved along the patient 22, as indicated by arrows Z7, andused to treat subsequent regions.

The spatial and temporal properties of the optical field40 determine the efficacy of the hair-removal process, and some

of these properties may, if desired, be adjusted using a seriesof controls 24, 26, 28 located on various components of thehair-removal system 10. For example, using controls 24located on the power supply, the optical intensity and pulse

45 repetition rate of the irradiating field can be controlled byadjusting parameters such as the voltage, current, andswitching rate for the laser's power supply. Other propertiesof the field, such as the wavelength and pulse duration, maybe varied by controls 26 which adjust components (e.g.,

50 gratings, mirror or filter positions, shutters, or pulse-formingmeans) of the light source 12; however, for preferredembodiments wavelength would not be adjusted. Similarly,controls 28 can be used to adjust the modulating optics 14,resulting in control of properties such as mode quality, beam

55 diameter, and coupling of the irradiating field into the fiberoptics 16. All controls may be adjusted by hand; and thesystem may also be operated (Le. the laser turned on) byhand or, alternatively, by using a foot pedal 30 connected tothe system 10.

In alternate embodiments, the light source, couplingoptics, and irradiation unit may be encompassed in a single,hand-held device. In this case, the light source is preferablyan array of diode lasers coupled directly to the irradiatingunit, and is powered by a small external power supply. The

65 compact nature of this type of optical system allows for amore controllable, maneuverable device, and additionallyobviates the need for fiber optic delivery systems.

60

5,735,844

cooling means are used, the temperature of the surface layeror epidermis of the skin is reduced to between 4°_15° C. Inaddition, in this case, it is preferred that a short time period(e.g., about 1 second) be allowed to elapse before irradiation

5 in order to ensure that the epidermis is adequately cooled.An external casing 39, as indicated in FIG. 2B by the dashedline, or a fiber-coupling housing 37, as shown in FIG. 2A,may be used to connect the light-delivering means to thehousing 48.

10 With reference now to FIG. 3A, the contact device 46 ispreferably formed into a lens shaped in order to converge theirradiating field, preferably near the base of the hair follicles40. In order to converge light, the contact device must beoptically transparent at the irradiating wavelength, and pref-

15 erably has a biconvex or plano-convex lens shape, prefer-ably with an f number less than or equal to fll.O, and a focallength of between about 0.5 and 2 em. Control over thesurface shape of the contact device allows the convergedlight field 38' to simultaneously irradiate various target

20 portions of the hair follicle, resulting in efficient destruction.Typically, each irradiated hair shaft has a diameter of about

With reference now to FIGS. 2A and 2B, the applicator or 75 microns, with the entire follicle having a diameter ofirradiating unit 18 of the hair-removal system allows deliv- about 200 microns. After passing through the contact deviceery of the irradiating field 38 to hair follicles 40 located in 46, the light field 38' is preferably converged through thethe region 20. As shown in FIG. 2A, the field 38 may be 25 epidermis 56 of the skin layer (having a thickness, e.g., ofdelivered to the irradiating unit 18 using a fiber optic cable about 0.1 rom) and is condensed in the dermis 58 near the16 (or other fiber optic device) containing one or more fibers papillae 54 of the follicles 40. Because dermal thicknessor fiber optic bundles. In this case, after exiting the varies greatly over the body, the papillae may be superficialwaveguide, the field 38 is typically spatially dispersed, and (as in, e.g., the eyelids and scrotum), but for most areas ofis preferably collected and roughly collimated using apiano- 30 interest (e.g., the face, axillae, and legs) the papillae areconvex lens 42. Alternatively, as shown in FIG. 2B, the field located at depths of approximately 4 to 7 rom beneath themay be delivered to the irradiating unit using, for example, epidermal surface. Located a few tenths of a millimeterone or more reflecting mirrors 44. This allows the field 38 to below the papillae are neurovascular bundles 60 which servebe roughly collimated prior to impinging on the lens 42. the metabolic and other needs of a hair matrix, the region ofDepending on the focal length of the lens 42 and the mode 35 rapidly growing keratinizing cells, located in the papilla,quality of the irradiating field, the field is preferably con- which produce the hair shaft 55. The matrix, papilla, and thedensed using, e.g., a plano-convex lens as shown in the corresponding vascular bundle, as well as the bulge near thefigure. After passing through this optic, the beam then center of the follicle, represent the follicular targets to beimpinges on a lens or contact device 46 which is placed in irradiated/destroyed. Preferably, during irradiation of thesecontact with the skin region 20. The optical and mechanical 40 regions, the field is pulsed, the pulse duration of the irra-properties of the contact device 46 are chosen to allow diation being kept short enough so that damage is localizedefficient coupling of the optical radiation into the skin region to a small region of dermis (typically within about 0.2 rom)(resulting in a delivered field 38) and the thermal properties surrounding each follicle in accordance with the principlesof the contact device are chosen to allow efficient coupling of selective photothermolysis. The extent of damage isof heat from the skin region. Once delivered, the field is used 45 preferably much less than half the distance between neigh-to irradiate, heat, and then destroy the hair follicles 40. The boring follicles (typically between 1 and 4 rom); if it iscontact device 46, in addition, is used to couple light and significantly greater than this, the light-induced injury mayheat out of the superficial skin layer (i.e., epidermis) of the result in a third-degree burn.irradiated region. This allows the light-absorbing pigment In addition to providing a light converging function, a(i.e., melanin) contained within the deep part of the hair 50 contact device 46 having a convex-shaped surface 62 allowsfollicles to be irradiated and selectively heated, permitting efficient compression of the skin during contact. Compres-pennanent destruction of the follicle, while potentially del- sion of the dermis 58 located near the surface 62 of theeterious optical and thermal energy are simultaneously con- contact device decreases the distance between this regionducted out of the overlying skin layers. Thus, multiple hair and the papillae; depending on the force applied, the dis-follicles can be destroyed, permanently removing hair from 55 tance may be decreased by up to several millimeters.the skin region without causing substantial pain or injury to Because the radiation field 38' is scattered. and correspond-the patient. The destroyed follicles are ultimately removed ingly attenuated during propagation through the dermis,by the body. compression of the skin results in bringing more light to the

Both the lens 42 and contact device 46 are preferably deep portions of the hair follicles for more efficient light-disposed in a housing 48 containing both entrance 50 and 60 induced heating of the papilla. In addition, compression ofexit 52 ports for fluids such as cooling water and pure gas the dermis by the contact device using a pressure greater(i.e., nitrogen to prevent condensation on the lens) to flow than the patient's blood pressure forces light-absorbinginto and out of; fluids may be used, for example, to cool the blood out of the irradiated region (indicated during treatmentcontact device 46, which, in ram, cools the skin surface. by a whitening of the skin in the pressurized region). ThisAlternatively, the housing 48 may include an electrically 65 reduces absorption of the optical field, resulting in morecontrolled cooler in order to provide accurate control over efficient delivery of light to the follicular target regions.the temperature of the contact device 46. Preferably, when Pressure applied using a contact device having a convex

5In order to effectively destroy the irradiated hair follicles

without causing damage to the surrounding skin, the lightfield supplied by the system 10 and the irradiating unit 18 isdesigned to maximize the amount of light-induced heatdeposited in the hair follicles, while reducing the degree ofinjury to the surrounding skin. It is preferred, for example,to deliver sufficientoptical energy to several "target" regionson the hair follicle; radiation delivered to these regionsresults in complete and localized destruction of the follicles.

Prior to treatment, the region to be treated may be shavedin order to facilitate irradiation of the follicles. Alternatively,as will be discussed later, hairs in the region may be epilatedand a chromophore may be applied to region 20, whichchromophore migrates into the empty follicles. Excess chro-mophore may then be removed from the skin surface priorto irradiation. Prior to treatment, an anesthetic may also beinjected locally or applied to the skin surface and followingtreatment, patients may be treated with topical antibioticointments.

6

MECHANICAL SlRUCfURE

5,735,8447 8

swface results in a relatively uniform displacement of bloodfrom the skin region. A contact device having this shape istherefore preferred to a flat device, which tends to produceregions having center portions which are not entirely blood-free.

In alternate embodiments, the contact device may bemounted in the housing in a spring-loaded fashion so that itmay be forced against the skin swface with an adjustablepressure. In addition, in this embodiment, the spring mecha-nism may be attached to a sensor and readout device so thatthe exact pressure applied to the skin swface can be accu-rately monitored and/or controlled.

When forced against the skin, the contact device 46allows optical radiation to be coupled into and out of theepidermis. With reference now to FIG. 3B, the refractive 15

index (neD) of the contact device 46 should be approxi-mately matched to that (nEP) of the epidermis 56, which isapproximately 1.55. Because light travelling from onerefracting media (i.e., the contact device) to another (theepidermis) is reflected at the interface 57 separating the two 20

regions by an amount related to the square of the refractiveindex difference, nearly index-matching allows efficientcoupling of the irradiating field into the skin. Thus, a contactdevice composed of a material having a refractive index near1.5 or somewhat greater allows the incident irradiating field 25

to undergo minimal reflections (indicated in the figure by thearrow 64) at the epidermislcontact device interface 57.Similarly, as indicated in the figure by the arrows 66, opticalfields within the dermis are back-scattered towards theepidermis due to diffuse reflectance. These back-scattered 30fields contribute to unwanted epidermal heating, and areeasily coupled out of the skin using the index-matchedcontact device 46. This allows minimization of the light-induced damage to the epidermis 56, while allowing effec-tive irradiation of the follicle target silos within the dermis. 35

Inpreferred embodiments, in order to be substantially index-matched, the contact device is preferably formed of ahigh-density material such as sapphire (ncv=1.7), fusedsilica (nev=1.5), or similar optically transparent glasses orplastics. In order to provide a convergent field entering the 40

skin and to have the convex shape of the contact device asshown, it is advantageous to use sapphire, the slightly higherindex of which facilitates the desired field convergence.

With reference now to FIG. 3C, in order to conduct heataway from the epidermis, it is additionally preferred that the 45contact device 46 be composed of a material having a highthermal conductivity (keD) which is similar to that of theskin. This allows efficient transfer of heat (indicated in thefigure by the arrows 68) from the epidermis 56, across thecontact device/epidermis interface 57, and into the contact 50device 4(i. A high thermal conductivity, in addition, isnecessary to minimize local heating effects that may occurat the interface 57, thereby reducing the chance of thermallyinduced damage or injury to the irradiated epidermis. As willbe discussed later, this is particularly important when the 55contact device is cooled. Ideally, the thermal properties ofthe contact device and the time the contact device is appliedto the skin before irradiation begins allow minimization ofheating near the epidermis, but have little effect on heatdeposited near the papillae of the hair follicle (shown in the 60figure as region 70). Materials having high thermal conduc-tivities include sapphire (Keu=O.083 cal sec-l cm-20C.em-l along the C axis at 30° C.), fused silica (KeD= 0.026cal sec-l cm-2 ·C. em-l along the C axis at 30° C.), as wellas other high-density glasses and plastics.

In addition, in order to improve both optical (i.e., trans-mission of back-scattered light) and thermal (i.e., heat

conduction) properties at the contact device/epidermis inter-face 57, it is desirable to apply to the skin a topical liquid oremollient, such as a lotion, water, alcohol, or oil, having arefractive index which is similar to that of the contact device

5 46 and epidermis. For example, application of an oil havinga refractive index between that of the epidermis (n=1.55)and sapphire (n=1.7) minimizes optical reflection effects atthe interface, thereby allowing more efficient transfer oflight into the skin region from the contact device and of

10 back-scattered radiation from the skin region. Also, a liquidallows for more efficient transfer of heat by conduction fromthe skin into the sapphire, thereby reducing the degree ofdamage or injury to the epidermis.

OPTICAL PROPERI'IES

The temporal and spatial distribution of intensity for theirradiating optical field inside the skin ultimately determinethe amount of heat deposited into the target regions of thehair follicle; these properties therefore can be selectedand/or adjusted to optimize the hair-removal process. Inparticular, properties which affect the hair-removal processinclude the pulse energy, pulse duration, repetition rate (i.e.,the time duration between subsequent pulses), wavelength,energy, exposure spot size, beam convergence as it enters theskin, and mode geometry (i.e., spatial extent and uniformity)of the optical pulse. These characteristics may be selectedaccording to the pigment present in the hair and skin to beirradiated; preferably, each parameter is adjusted so that thetemperature at each target site, immediately followingirradiation, is elevated to between about 80° and 120° C.Heating the follicle to this temperature leads to permanentdamage and subsequent removal.

Referring now to FIG. 4, the wavelength of the irradiatingfield is chosen to be resonant with the natural pigment (Le.,melanin) present in the target sites (i.e., the hair shaft, bulge,matrix, and papilla). The absorption spectra of melanin,water, hemoglobin, and oxyhemoglobin shown in the figureindicate the ability of these compounds to absorb opticalradiation at different wavelengths; low absorption indicatesthat light at the particular wavelength will penetrate deeperin the absorbing media. In general, in order to selectivelyheat the target regions, the wavelength of the irradiating fieldis chosen to match the absorption spectrum of melanin,which basically absorbs light from about 200 to 1200 nm;conversely, the wavelength is mismatched to the absorptionspectra of compounds contained in the skin, such as waterand hemoglobin. Light having wavelengths between 680and 1200 run, a range indicated by the arrow 70 in the figure,is effectively absorbed by melanin while being relativelytransmitted by both hemoglobin and water, and therefore canbe used for selective heating of pigmented hair surroundedby white or lightly tanned skin. In particular, light in therange of 680 to 900 om or 1000 to 1200 nm is preferred, asthis radiation is strongly absorbed by melanin, and will notbe absorbed by the bands present in water and in oxyhemo-globin near 950 run. For patients with less melanin presentin the hair follicles (e.g. with auburn or light brown hair), theshorter wavelengths in this region are preferable because ofthe higher absorption coefficient of melanin. In addition,other light-attenuating effects besides absorption, e.g., scat-tering of radiation, are also wavelength-dependent, andshould be considered during selection of the optical field'swavelength. For example, in human skin, the penetration oflight is partially determined by the transport scattering

65 coefficient (11.), which decreases at longer wavelengths dueto scattering in the dermis. For radiation at 1000 nm, 11. isabout 10 em-l; light propagating into the skin from a

5,735,8449 10

generally index-matched medium at this wavelength will instance, intra-cavity modulation of the light field usingtherefore reach a maximum intensity at about 1 mm below electro or acousto-optic Q-switching devices allows genera-the skin surface. tion of pulses having temporal profiles which are typically

Sources generating visible or near-infrared light in the Gaussian in shape. Pulses made using these methods arepreferred range of 680-1200 nminclude diode (Ar<800-1000 5 typically too short, however, having durations in the sub-nm), Nd:YAG and Nd:YLF (A.=1064and 1053 nm), Ti:Sap- microsecond range. Normal-mode pulses produced byphire and infra-red dye (Ar<700-1000nm), ruby (A.=694nm) fIashlamp excitation of ruby, alexandrite, Ti:sapphire, orand alexandrite (A.=700-&50nm) lasers. Ruby, Nd:YAG and Nd:YAG lasers are preferred because these typically arediode lasers (particular arrays of diode lasers) are preferred high-energy pulses in the 0.1-10 ms pulse duration region.as these sources are commercially available, well- 10 Alternatively, a continuous (Le., time-independent) opticalcategorized, and can be manufactured on a small scale. Ught field emitted by a laser can be externally modulated using,sources of this type can be incorporated into compact for example, a mechanical shutter or electro-optic gate.hair-removal devices which, in turn, can be easily manipu- Modulation using external methods allows the pulse widthlated by the operator during hair-removal procedures. to be easily varied from a few hundred microseconds to

The duration of the optical pulse can also be controlled in 15 several hundred milliseconds. Pulses generated using exter-order to vary the heating of the hair follicle. Referring now nal modulation may also have "square wave" temporalto FIG. SA, the optical pulses, indicated by the waveforms profiles (as shown in FIG. SA) which allow a more uniform74,74', preferably have durations 76,76' which allow the optical field to be applied to the region of interest However,follicle to be heated for short periods of time. The pulse external modulation is not used for currently preferredwidth is controlled to vary the heat conduction during the embodiments.optical pulse, and thus the damage of the follicle and its 20immediate surrounding dermis; too little damage results in When a contact device is used to deliver the optical pulse,hair re-occurrence, while extensive damage may produce a time delay preferably exists between the time at which thescarring in the irradiated region. Preferably, the pulse dura- contact device contacts the skin surface and the arrival of thetion 76, 76' is between about 2 ms and 100 ms. pulse. This allows the entire epidermal layer 56 to be cooled

The exact pulse duration is dictated by the diffusion of 25 significantly prior to irradiation, thereby increasing its dam-heat in the skin, a process which roughly follows the heat age threshold. Pain and damage to the epidermis are thusdiffusion equation relating the diffusion- time t, diffusion reduced and are further minimized by continuing to cooldistance d, and thermal diffusivity k, as discussed by in contact device 46 during irradiation so that heat continues toWelch, A. J. 'The thermal response of lasef~iiiac:liated be removed from the epidermis. However, heating at lowertissue", lEEE J. Quant. Electron. QE-21 (12), 1471-1481 30 levels where destruction of the follicles, and in particular the(1984):t=d?14k (kfor the human dermis is roughly 13xlO-3 bulge and papillae thereof, is desired is not affected by thecrn2/sec). The time needed for extraction of heat from the _c()olin,gperformed either before and/or during irradiation.epidermis during a laser pulse is approximately 2 ms, and In addition, the time duration between optical pulsesthe thermal relaxation time for a typical 200 micrometer hair (indicated in FIG. SA by the arrow 78) may be adjusted infollicle is approximately 40 ms. For light exposures longer 35 order to control the total amount and rate on average of heatthan a few hundred milliseconds, too much thermal diffusion deposited into the irradiated region. If repetitive illuminationmay occur during the exposure period, resulting in either is required for destruction of the follicle, this time period isinefficient destruction of the target regions of the hair preferably constant and lies between several seconds and afollicle, excessive dermal damage, or both. Further, since few hundred milliseconds. Alternatively, for "single shot"most of the melanin (roughly two thirds) in the epidermis is 40 illumination, this time period is selectively controlled by thein the lower portion of the epidermis, heating of the epider- operator. In this case, a single laser shot is delivered to themis occurs primarily in the deeper portions thereof, and region of interest, and then the region is inspected by thesome time is required for this heat to reach the surface in operator for damage. If more radiation is required, additionalorder to be removed by the contact device 46. Therefore, laser shots can then be delivered to the region. Otherwise,since this timeis at least 2 ms, this is the minimum suggested 45 the irradiation unit is translated and used to treat a separatepulse duration, with a longer time, preferably at least 5 ms, region.being suggested to minimize epidermal damage. Further, The spatial extent of the optical field is chosen to allowdepending on the laser utilized, each pulse could be in the multiple hair follicles to be irradiated with a single laserform of a single continuous pulse as shown in FIG. SA or in shot. In addition, larger spot sizes are preferred becausethe form of a train of closely spaced pulses of shorter 50 attenuation along the beam axis within skin due to scatteringduration, the space between such closely-spaced pulses decreases as the beam radius, R, increases. Thus, wide-areabeing much shorter than 5 ms. beams allow more efficient delivery of optical radiation to

For a given fIuence, the intensity of the optical field is the deep target sites. Referring now to FIG. SB, the width 80inversely related to the pulse duration; thus, when the pulse of the spatial profile 82 of the irradiating beam at the surfaceduration is below about 10 ~, large optical intensities may 55 of the skin is preferably on the order of, and preferably muchresult in undesirable modes of damage to surrounding skin greater than, the depth of the target to be irradiated. Mostregions. In addition, short pulses may result in localized preferably, the beam diameter is at least 8 mm. The area ofheat-induced "explosions" in the follicle which cause the irradiating field is preferably between about 0.5 and 2mechanical damage to the skin. In particularly preferred cm2, and is most preferably between 0.75 and 1 c~.embodiments, the pulse has a duration or pulse-width of 60 Because the beam is preferably converged, the spatial profileabout 2-100 ms. During this time period, thermal diffusion will be condensed as a function of depth before reaching atakes place over a distance of about 0.05 to 0.3 mm; damage waist at a depth defined by optical scattering in the dermis.confined to about this distance results primarily in destruc- Preferably, as shown in FIG. SB, the intensity across thetion of the irradiated hair follicles, with little or no damage beam diameter is roughly constant in order to provide ato the surrounding skin. 65 substantially uniform irradiating field.

Optical pulses having well-defined and adjustable dura- Referring now to FIG. 6, following illumination, thetions may be generated using known techniques. For intensity distribution of optical radiation (Le., the y axis in

5,735,84411

the figure) as a function of skin depth (i.e., the x axis) iscalculated using Monte Carlo-based computer simulations.The distribution is a function of the beam's spatial profile,the optical properties of the medium in contact with the skin.Although the plotted data is based on a computer simulation, 5and is thus only an approximate, the x axis units areestimated to be about 500 microns per tick mark. The firstcurve 90 shows the skin depth-dependent properties of anoptical field originating from a small, collimated spot of 800om light in air. In this case, the majority of the optical 10

intensity is distributed near the surface of the skin (indicatedby the "0" point along the x axis), with the intensitydropping off rapidly at larger depths. A larger, collimatedspot originating from air (curve 92) has a more evenlydistributed skin depth-dependent intensity, although the 15

majority of the light is still concentrated near the skinsurface. Delivering a large, collimated radiation spot from amaterial having a refractive index of 1.5 (curve 94) resultsin a relatively uniform optical intensity in the first millimeteror so of the skin; at larger depths, this intensity starts to tail 20off with a relatively slow time constant. Finally, in thepreferred embodiment, a large, spatially converging opticalfield from the n=1.5 refracting material has an intensity atthe skin surface which increases to a maximum after propa-gating about a rnillirneter into the skin. The intensity then 25

attenuates as a function of skin depth with a time constantslower than that exhibited by the curve 94. Thus, a field ofthis type can be used to effectively heatthe target sites of thefollicle, with reduced heating of the skin at the surface, thusreducing heat injury to the skin.

In the case where the illuminating laser generates a beamhaving a diameter less than the preferred values, it may benecessary to expand the beam prior to delivery to theirradiating unit. This may be done with conventional tele-scoping optics, e.g., two-lens systems configured to first 35expand and then collimate the emitted beam. Alternatively,as shown in FIG. 2A, the irradiating field may be coupledinto an optical fiber and then delivered to the irradiating unit.In this case, the emerging field is naturally dispersed due tothe waveguide nature of the fiber, and is then collected by a 40collimating lens. Displacement of the lens from the fiber tipallows the irradiating beam's profile to be increased to thedesired amount.

The fiuence of the optical field will be varied according tothe degree of pigmentation in the patient, and is preferably 45between about 10 and 200 J/cm2 for each pulse; patientswith darker hair will require lower fiuence than patients withlighter hair. Most preferably, the pulse fiuence of the irra-diating field for pulses of about 1 ms duration is between 30and 50 J/crn2• As described herein, in all cases, the fiuence 50

is adjusted in order to heat the target regions to the desiredtemperature of approximately 80° to 120° C. Moreover, thelevel of fiuence may be increased as the pulse duration isincreased in order to compensate for less efficient heating offollicles due to heat conduction during long pulses. It may 55be necessary to increase or decrease the optical fiuence inorder to heat the hair follicle to the desired temperature if thewavelength of the irradiating light field does not lie in thepreferred spectral regions (i.e., 680-900 om or 1000-1200om). In addition, in cases where the laser output is below the 60desired optical fiuence, it may be necessary to amplify theindividual pulses prior to irradiating the skin. Opticalamplifiers, such as external optical cavities, may be used forthis purpose.

Table 1, shown below, lists the preferred parameters of the 65optical fields used for hair removal. The value of eachparameter depends on the amount of hair in the region of

12interest, the degree of pigmentation of the hairs, and thepigmentation of the surrounding skin of the patient.

TABLE 1

Preferred Optical Field Parameters

Parameter Range Preferred Values

Wavelength 680-1200 run 680--900,1000-1200 run

2-100 IDS0.75-1.0 em2

3O-S0 J/em2

n = I.S to 1.7f# 0.5-2

Pulse DurationBeam AreaPulse EnergyOptical CouplingBeam Convergence,At Skin Surface

SO~-200 IDS>O.S cm2

10--200 J/cm2

external n ;:; 1.4collimated or

convergent

The inventions will now be further described with refer-ence to the following examples.

EXAMPLESIn order to demonstrate the efficacy of the hair-removal

device according to the invention, in vitro black-haired dogskin was exposed to light from the normal mode of a rubylaser at A.=694 om With a pulse duration of 270l1s and opticalfiuences of 40 J/cm2, 71 J/cm2, and 160 J/cm2

• The spatialextent of the beam (8 rom diameter at the skin surface)allowed irradiation of approximately 100 hairs with a singlelaser shot. Following irradiation, each skin region wasexamined histologically. Examination revealed that at the

30 highest fiuences, dermal damage consistent with scarring ofthe skin was evident, indicating that at the highest fiuences,light-induced thermal damage was not selective to the hairs.In contrast, at the lower fiuences, and particularly at 40J/cm2, localized follicular damage was observed. with nonoticeable damage occmring in the neighboring skin regionsor dermis between hair follicles.

In a separate set of experiments, in order to show that thetemperature increase within the irradiated hair is dependenton the degree of pigmentation, fresh human hair and skinsamples having different colors were exposed using thehair-removal method described herein. The light source forall experiments was the ruby laser described above. :Emittedlight was first coupled into an enclosed beam-steering devicecontaining several mirrors coated to have high refiectivitiesat 694 om, and then delivered to an irradiating unit similarto that shown in FIG. 2B. The unit included a 5-cm plano-convex glass lens positioned at the proximal end of awater-cooled plexiglass housing. A sapphire contact deviceshaped as a l-cm focal length lens was disposed at the distalend of the contact device, with the convex side touching theskin to allow compression during exposure as describedabove. Human skin was irradiated with an 8 rom diameterbeam by pressing the cooled (4° C.) contact device againstthe skin region of the patients, and then delivering a singlelaser shot. Each shot typically resulted in the simultaneousexposure of about 10 hairs.

The skin and hair of six adult patients having hair colorranging from red to black was irradiated and then observed.In each patient, eight treatment sites, each having an area of10 cm2, were irradiated. In order to monitor destruction ofthe papilla, sites 1-4 were wax-epilated prior to exposure tolaser light, while sites S-8 were shaven prior to exposure.Each site then received an optical fiuence of either 28 J/cm2

,

42 J/cm2, or 57 J/cm2• Patients were seen in follow-upexaminations one month and three months (and for somepatients also one year) after exposure. As seen from thephotographs of the exposed regions shown in FIG. 7 (Le.,

13regions A-C), hair regrowth after three months was minimalor non-existing in all cases compared to the shaved-but-untreated region (Region D), clearly indicating permanentdamage to the hair follicle. In the figure, sites A-C were

5treated with decreasing energy from the laser. It is clearlyevident that hair removal is relatively less pronounced inregion C, treated with a fluence of 27 J/cm2• Region D, thecontrol region, was shaven at the same day regions A-Cwere treated. In addition, histological specimens obtained 10from the treated sites revealed that damage occurred exclu-sively to the hair follicle, while the surrounding dermis wasessentially spared. There was statistically significant loss ofhair for all of the subjects in the laser-treated sites comparedwith unexposed, shaven control sites. At one year later, there 15

was also significant permanent hair loss without any scar-ring.

A separate set of experiments permitting measurement ofthe time-dependent temperature characteristics of hair andskin samples were conducted using a pulsed photothermalradiometry (PPTR) apparatus. In these experiments, the rubylaser described above was used at lower fluences to provideoptical pulses having an energy allowing heating, but notdestruction, of the follicles. Output from the laser wasfocussed onto the samples of human hair and skin to providea uniform excitation field. A New England Research, Inc.black-body radiation detector containing an amplified, liquidnitrogen-cooled HgCdTe detector was used to monitor time-dependent characteristics of the sample temperature, and aGentec, Inc. laser energy meter was used to monitor theirradiating pulse. The output from both detectors was thenamplified with a compensated 0--10 Mhz dc-coupledpreamplifier, and then relayed to a digital oscilloscope forrecording and storing the data.

Eight patients having various skin types and hair coloringranging from redlblonde to black were studied. In general,the PPIR results indicated that following irradiation at 694run, black hair experienced a larger temperature rise thanlighter brown hair, and that both of these specimens expe-rienced higher temperature rises compared to redlblondehair. In addition, following irradiation, type IT skin had alower temperature rise than type m or type IV skin.

Referring now to FIGS. 8A-8C, in a particular exampleusing a patient with black hair and white skin, time-dependent traces measured using the PPTR apparatus indi-cate that 400 IDS after irradiation, both wet and dry black hairexperience, respectively, temperature rises of about 70 C.and 720 C. (FIGS. 8A and 8B) from a baseline temperatureof 23 0 c., whereas the surrounding skin (FIG. SC) under-goes a temperature rise of less than 10 C. The difference inthe temperature rise and time-dependent decay characteris-tics of the wet hair is likely due thermal effects (e.g., thehigher heat capacity of wet hair).

Referring now to FIG. 9, in all cases, the normalizedtemperature rises (i.e, the ratio of temperature rise to laserpulse energy) in the wet and dry hair follicles were signifi-cantly higher than those measured in the skin, indicatingselective heating of the follicles using the method of theinvention. Table 2, shown below, lists the hair and skin typesof each patient in the study. The patient numbers in the tablecorrespond to the patient numbers in FIG. 9.

5,735,84414

TABLE 2

Patient Hair and Skin T~s

Patient Hair Skin 1YPe

1 Red II2 Brown ill3 Brown II4 GrayJBlack ill5 GrayJBlack ill6 DaIkBrown ill7 GrayJBlack II8 Black ill

OTHER EMBODIMENTS

FIG. lOA illustrates an alternative embodiment of theinvention wherein the region 20 is epilated rather than beingmerely shaved prior to treatment in accordance with the

20 teachings of this invention. A fluid solution or suspension100 containing a chromophore may then be applied to theskin region 20, with the chromophore containing fluidmigrating into the empty follicles and filling the follicles."Capillary action" of the fluidlchromophore into the follicles

25 is desirable and may be enhanced by providing a low surfacetension between the fluid and skin, for example by usingsurfactants or solvents. The excess fluidlchromophore maythen be removed from the skin surface by washing, wipingor stripping. During irradiation, the chromophore 100 in the

30 follicle absorbs light and is heated and, along with theheating of the melanin of the follicle itself, results insignificant heating of the follicle to destroy the portionsthereof, including the bulge and the papilla, required toprevent regrowth of hair. The chromophore therefore must

35 absorb light at the wavelength or wavelengths used forirradiation. Suitable chromophores might include a carbon-particle sUspension or a dye such as methylene blue orindocyanine green. Melanin itself in liposomal form mightalso be used. Since the chromophore is only in the follicles,

40 this technique maximizes damage to the follicles whileminimizing damage to surrounding tissue, and for thisreason is a preferred way of practicing the invention, espe-cially for those with blond, red, light brown or other lightcolored hair. Except for the differences indicated above, this

45 embodiment of the invention operates in the same mannerdescribed for earlier embodiments, including the cooling ofcontact device 46, the deformation of the skin in the region20, and the preferred optical irradiation, with the exceptionthat lower frequency may be allowed when using the chro-

50 mophores.FIG. lOB illustrates another alternative embodiment of

the invention wherein the contact device or applicator 46' ismodified so as to simultaneously expose both sides of a skinfold. This further increases the relative delivery of light to

55 the deep portion of the follicles. In FIG. lOB, the contactdevice has for example an opening or slot 110 in the face ofthe applicator into which the area 20 of the skin may bedrawn by for example vacuum or suction being applied toline 112 leading into the top of slot 110, the skin in slot 110

60 being formed into a fold 113. Radiation may be appliedthrough a fiber-optic bundle 114 which divides to apply theradiation to lenses 116 on either side of slot 110. CooliIigwater may be flowed over the surfaces of lenses 116 througha line 118. Alternatively, two applicators similar to those

65 shown for example in FIG. 2A or 2B can be positioned onopposite sides of a skin fold formed by clamping the skinregion therebetween or by other suitable means.

15The advantage of folding the skin as discussed for the

above embodiments is that radiation is applied to a relativelythin section of skin from both sides. Thus, the papilla of agiven follicle may be receiving radiation not only from thelens 116 on the side of slot 110 where the follicle is located,but also some radiation from the lens 116 on the oppositesides of the slot. Thus, energy applied to the papilla of eachfollicle is increased without increasing the energy at thesurface, thus facilitating hair removal with less pain andinjury. By making the slot 110 relatively narrow, pressure isapplied to the skin on both sides of the slot, the skin beingcompressed between the walls of the slot. The advantages ofcompressing the skin, including removing blood therefromand reducing the distance from the skin surface to thepapilla, are thus also achieved by this embodiment of theinvention. Clamping to form the fold would also applypressure to the skin.

It may also be possible to utilize the teachings of thisinvention for short term hair removal, the device serving asfor example a razor which might provide a shave lasting forperhaps one to two weeks. This is achieved by applying thefiuidlchromophore to the region which is to be "shaved"which region has preferably been shaved using conventionaltechniques, but not epilated. In this case the chromophorecan only migrate a few millimeters into the follicle, to forexample the level of the sebaceous gland. Excess chro-m~ore may then be removed, and the contact device ofthis invention utilized with relatively low level radiation toheat the chromophore, and destroy the hair surroundedthereby, without substantial damage to either the skin orfollicle.

Further, while cooling water has been shown for thepreferred embodiment to cool contact device 46, this is nota limitation on the invention and other cooling techniquesmay be utilized. For example, a low temperature gas orliquid gas may be passed over the contact device for coolingpwposes or the contact device may be sufficiently cooledprior to use so that it can continue to perform the coolingfunction during irradiation without having a coolingmedium passed thereover. Other cooling techniques known 40

in the art may also be utilized.Other embodiments are within the scope of the following

claims. For example, the contact device may not be cooledor cooling of the epidermis may be performed without anapplicator (for example cryogenically). Where an applicatoris not utilized, radiation is applied directly to the region ofinterest after passing through the appropriate optics.

Thus, while the invention has been particularly shown anddescribed above with reference to preferred embodiments,the foregoing and other changes in form and detail may bemade therein by one skilled in the art without departing fromthe spirit and scope of the invention.

We claim:1.A method for the simultaneous removal of a plurality of

hairs from a skin region, each hair being in a follicle 55extending into the skin from a skin surface, the methodcomprising the steps of:

(a) placing an applicator in contact with the skin surfacein said skin region;

(b) applying optical radiation of a selected wavelengthand of a selected fiuence through said applicator to saidskin region, said applying step lasting for a predeter-mined time interval; and

(c) utilizing said applicator at least during step (b) to coolthe skin surface in said skin region to a selected depth;

said selected fiuence and said predetermined time intervalbeing selected such that there is at most minimal heating of

5,735,84416

skin in said skin region to said selected depth, while causingsufficient heating of at least one of hairs and follicles belowsaid selected depth to at least damage said hairs and follicleswithout causing significant damage to tissue surrounding

5 said follicles.2. A method as claimed in claim 1 wherein the skin has an

epidermis layer which is the layer of the skin closest to saidskin surface, and wherein said selected depth is substantiallythe depth of said epidermis layer.

10 3. A method as claimed in claim 1 wherein step (c)includes the step of (d) cooling at least the surface of saidapplicator in contact with said skin surface both during step(b) and prior to the performance thereof.

4. A method as claimed in claim 3 wherein step (d) is15 performed by passing a cooling fiuid through said applicator.

5. A method as claimed in claim 3 wherein step (b) is notperformed until the skin surface in said skin region has beencooled to substantially said selected depth.

6. A method as claimed in claim 1 wherein said selected20 fiuence and said predetermined time interval are such as to

result in the substantial destruction of said follicles.7. A method as claimed in claim 1 wherein said selected

time interval is 2 to 100 rns.8. A method as claimed in claim 1 including the step

25 performed before step (a) of shaving the hairs in said skinregion.

9. A method as claimed in claim 1 including the stepperformed before step (a) of epilating the hairs in said skinregion.

30 10. A method as claimed in claim 9 including the stepperformed after the epilating step but before step (a) offilling the follicles from which the hairs have been epilatedwith a substance which preferentially absorbs optical radia-tion at said selected wavelength.

35 11. A method for the simultaneous removal of a pluralityof hairs from a skin region, each hair being in a follicleextending into the skin from a skin surface, the methodcomprising the steps of:

(a) placing an applicator in contact with the skin surfacein said skin region; and

(b) applying optical radiation of a selected wavelengthand of a selected fiuence through said applicator to saidskin region, said applying step lasting for a predeter-mined time interval;

45 said applicator converging the optical radiation applied tosaid skin region.

12. A method for the simultaneous removal of a pluralityof hairs from a skin region, each hair being in a follicleextending into the skin from a skin surface, the method

50 comprising the steps of:(a) placing an applicator in contact with the skin surface

in said skin region; and(b) applying optical radiation of a selected wavelength

and of a selected fiuence through said applicator to saidskin region, said applying step lasting for a predeter-mined time interval;

pressure being applied to the applicator during steps (a) and(b) so as to cause the applicator to deform the skin regionthereunder.

60 13. A method as claimed in claim 12 wherein the appli-cator has a convex surface in contact with the skin surface.

14. A method as claimed in claim 12 wherein the pressureapplied to said applicator is greater than blood pressure of apatient from whom hairs are being removed, whereby at

65 least some blood is removed from said skin region.15. A method for the simultaneous removal of a plurality

of hairs from a skin region, each hair being in a follicle

5,735,84418

extending into the skin from a skin surface, the method an element in said optical path for converging the opticalcomprising the steps of: radiation as it leaves the applicator through said sur-

(a) utilizing an applicator to forma fold of the skin in said face; andskin region, said applicator being in contact with the means for cooling said surface to a temperature below thatskin surface in said skin region on two substantially 5 of the skin region.opposite sides of said fold; and 22. An applicator as claimed in claim 21 wherein at least

(b) applying optical radiation of a selected wavelength said surface is formed of a material having a refractive indexand of a selected fluence through said applicator to said which substantially matches, but which is not less than, theskin region, said applying step lasting for a predeter- refractive index of the skin surface in said skin region.mined time interval, the optical radiation being applied 10 23. An applicator as claimed in claim 21 wherein saidto said two substantially opposite sides of the fold. element is a lens.

16. A method as claimed in claim 15 wherein the appli-cator has a slot formed in the surface thereof in contact with 24. An applicator as claimed in claim 21 wherein saidthe skin surface, wherein during step (a) at least a portion of means for cooling is a channel near said surface throughthe skin region is drawn up into said slot, and wherein during which cooling water is passed.step (b) optical radiation is applied to the skin region from 15 25. An applicator suitable for use in practicing the methodat least two opposite sides of said slot. of claim 1 comprising:

17. A method for the simultaneous removal of a plurality a housing;of hairs from a skin region, each hair being in a follicle a transmitter of optical radiation into said housing;extending into the skin from a skin surface, the methodcomprising the steps of: 20 a surface disposed on the housing shaped to contact the

(a) placing an applicator in contact with the skin surface skin surface in said skin region, said surface having ain said skin region, said step including the step of slot formed therein;providing a substantial refractive index match between an optical path from said inlet to through said housingthe applicator and the skin surface in said skin region; from said transmitter of optical radiation to opticaland 25 radiation at said selected wavelength, said optical path

(b) applying optical radiation of a selected wavelength leading to at least two opposite sides of said slot, andand of a selected fluence through said applicator to said including means for positioning at least a portion ofskin region, said applying step lasting for a predeter- said skin region into said slot;mined time interval. an element in said optical path for converging the optical

18. A method as claimed in claim 17 wherein step (e) 30 radiation as it leaves the applicator through said sur-includes the step of providing a layer of a refractive index face; andmatching substance between the applicator and the skinsurface in said skin region. means for cooling said surface to a temperature below that

19. A method for the simultaneous removal of a plurality of the skin region.of hairs from a skin region, each hair being in a follicle 35 26. An applicator as claimed in claim 25 wherein saidextending into the skin from a skin surface, the method means for positioning includes means for applying vacuumcomprising the steps of: to said slot.

(a) applying optical radiation of a selected wavelength 27. Apparatus for the simultaneous removal of a pluralityand of a selected fluence to said skin region, said of hairs from a skin region containing said plurality of hairs,applying step lasting for a predetermined time interval; each hair being in a follicle extending into the skin from aand 40 skin surface, the apparatus comprising:

(b) cooling the skin surface in said skin region to a an applicator which is adapted to be in pressure contactselected depth prior to step (a) and during step (a), said with a portion of the skin surface containing a pluralityselected fluence and said predetermined time interval of hairs in said skin region;being selected such that there is at most minimal 45 a source of optical radiation of a wavelength between 680heating of skin in said skin region to said selected and 1,200 nm., a fluence between 10 and 200 Jlcm2 anddepth, while causing sufficient heating of at least one of a pulse duration between 50Jis and 200 IDS; andhairs and follicles below said selected depth to at least means for applying the optical radiation from said sourcedamage said hairs and follicles without causing signifi- to said applicator, the optical radiation being passedcant damage to tissue surrounding said follicles; 50 through the applicator to said skin region.

whereby at least one of the hairs and follicles is heated and 28. Apparatus as claimed in claim 27 wherein said appli-damaged without causing significant damage to the skin cator has a surface in contact with the skin surface, andsurface in said skin region up to said selected depth. including a mechanism which cools said surface of the

20. A method as claimed in claim 19 wherein said selected applicator below that of the skin region by an amount whichdepth is substantially the entire epidermal layer depth in said 55 is sufficient in conjunction with selected radiation to preventregion, but does not extend significantly into the dermal substantial heating of the skin region in which said appli-layer. cator is in pressure contract for a selected depth and not to

21. An applicator suitable for use in practicing the method substantially interfere with heating of the skin in said regionof claim 1 comprising: beyond said selected depth.

a housing; 60 29. Apparatus as claimed in claim 28 wherein said meansa transmitter of optical radiation into said housing; for cooling includes a channel near said surface througha surface disposed on the housing having a convex shape which cooling water is passed.

and adapted to be in pressure contact with the skin 30. Apparatus as claimed in claim 28 wherein said sourcesurface in said skin region; of optical radiation is a laser, and wherein said selected

an optical path from said inlet to through said housing 65 duration is 2 to 100 IDS.from said transmitter of optical radiation to optical 31. Apparatus as claimed in claim 27 wherein said appli-radiation at said selected wavelength; cator has a surface in contact with said skin surface, said

17

5,735,84419

surface of the applicator having a slot formed therein,wherein the means for applying the optical radiationincludes C1'ticalpaths in said applicator leading to at leasttwo opposite sides of said slot, and wherein said applicatorincludes means for positioning at least a portion of said skin 5region in said slot between said at least two opposites sides.

32. A method for the simultaneous removal of a pluralityof hairs from a skin region, each hair being in a follicleextending into the skin from a skin surface, the methodcomprising the step of:

20(a) positioning an element over said skin surface in said

skin region through which optical radiation may bepassed; and

(b) applying optical radiation of a selected wavelengthand of a selected fluence through said element to saidskin region to simultaneously remove a plurality ofhairs from said region, said applying step lasting for aduration of from 2 to 100 ms.

* * * * *

111111111111111111111111111111111111111111111111111111111111111111111111111US005735844Cl

(12) EX PARTE REEXAMINATION CERTIFICATE (7214th)United States Patent (10) Number: US 5,735,844 ClAnderson et al. (45) Certificate Issued: Dec. 8,2009

(54) HAIR REMOVAL USING OPTICAL PULSES

(75) Inventors: R. Rox Anderson, Lexington, MA (US);Melanie Grossman, Boston, MA (US);William Farinelli, Danvers, MA (US)

(73) Assignee: The General Hospital Corporation

Reexamination Request:No. 90/009,216, luI. 10,2008No. 90/009,356, Dec. 8, 2008

Reexamination Certificate for:Patent No.: 5,735,844Issued: Apr. 7, 1998Appl. No.: 08/593,565Filed: Jan. 30, 1996

Related U.S. Application Data

(63) Continuation-in-part of application No. 08/382,122, filed onFeb. 1, 1995, now Pat. No. 5,595,568.

(51) Int. Cl.A61B 18/20 (2006.01)A61B 17/22 (2006.01)A61B 17/30 (2006.01)A61B 18/00 (2006.01)A61B 18/22 (2006.01)A61B 19/00 (2006.01)A61N 5/06 (2006.01)A61B 17/00 (2006.01)U.S. Cl. 606/9Field of Classification Search . 606/9See application file for complete search history.

(52)(58)

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(Continued)

Primary Examiner-David O. Reip

(57) ABSTRACT

A method and apparatus for simultaneously effecting theremoval of multiple hairs from a skin region by using lightenergy to destroy hair follicles in the region. Light energy isapplied to the region through an applicator which convergesthe light energy to enhance destruction of desired portions ofthe follicles, is preferably pressed against the skin region todeform the upper layers of the skin reducing the distancefrom the skin surface to portions of hair follicles which areto be destroyed, including the bulge and papilla of thefollicles, and which applicator is preferably cooled to mini-mize or eliminate thermal damage to the epidermis in theregion being irradiated. Parameters for the irradiation,including pulse duration, are selected to effect completedamage of desired portions of the hair follicles in the regionwith minimal damage to surrounding tissue and to thepatient's epidermis.

56

'--<--. ,3858

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Lage, et aI., "The Pathology of Laser Irradiation of the Skinand Body Wall of the Mouse", Laser Irradiation,47(4):643-663 (1965).Landthaler, et aI., "Neodymium-YAG Laser for VascularLesions", Journal of the American Academy of Dermatol-ogy, 14(1):107-117 (1986).Lask, et aI., "Laser Skin Resurfacing with the SilkTouchFlashscanner for Facial Rhytides", Dennatol. Surg.,21(12):1021-1024 (1995) Abstract Only.Lask, et aI., "Neodymium:Yttrium-Aluminum-GarnetLaser for the Treatment of Cutaneous Lesions", Clinics inDennatology, 13:81-86 (1995).Maiman, "A Look at Things to Com: Biomedical LasersEvolve Toward Clinical Applications", Hospital Manage-ment, Apr., pp. 39-41, (1966).Matsumoto, et aI., "Ruby Laser Treatment of Melanin Pig-mented Skin Lesions using Toshiba Model LRT-301A RubyLaser", Department of Plastic Surgery School of Medicine,Hokkaido University, 10(3):451-454 (1989) English Trans-lation.McKenzie, "Physics of Thermal Processes in Laser-TissueInteraction", Phys. Med. BioI., 35(9): 1175-1209 (1990).Meloy, "The Laser's Bright Magic", National Geographic,Dec., pp. 858-881, (1966).Mester, et aI., "The Biomedical Effects of Laser Applica-tion", Lasers in Surgery and Medicine, 5:31-39 (1985).Mester, et aI., "The Effect of Laser Radiation on HairGrowth of the Mouse", Radiobiologia Radiotherapin,9(5):621-626 (1968) English Translation.Mester, et aI., "Untersuchungen uber die hemmende bzw.fordemde Wirkung der Laserstrahlen", Langenbecks Ardenfuer Chirurgie, 322: 1022-1027 (1965) English Abstract.Miyasaka, et aI., "Basic and Clinical Studies of Laser forHyperpigmented Skin Lesions", pp. 117-127 (1991).Moy, et aI., "Skin Resurfacing of Facial Rhytides and Scarswith the 90-microsecond short pulse C02 Laser. Compari-son to the 900-microsecond dwell time C02 Lasers andClinical Experience", Dermatol. Surg., 24(12):1390-1396(1998) Abstract Only.Nakaoka, et aI., "The Square and Uniform Intensity RubyLaser for the Treatment of Pigmented Skin Lesions", Eur. J.Plast. Surg., 15:23-30 (1992).Nelson, et aI., "Dynamic' Cooling of the Epidennis DuringLaser Port Wine Stain Therapy", American Society for LaserMedicine and Surgery Abstracts, No. 253, Abstract Only.Nelson, et aI., "Dynamic Epidennal Cooling During PulsedLaser Treatment of Port-Wine Stain", Arch Dermatol,131:695-700 (1995).Ohshiro, et aI, "The Ruby and Argon Lasers in the Treatmentof Naevi", Annals Academy of Medicine, 12(2):388-395(1983).Ohshiro, et aI., Laser Treatment for Naevi, John Wiley &Sons, pp. 166-191, 195-201 (1995).Ohtsuka, et aI., "Ru Laser: Histological Studies and ClinicalExperiences of Ruby Laser Treatment", 11(4):107-115(1991) English Abstract.Oliver, "Dennal-Epidermal Interactions and Hair Growth",Journal ofInvestigative Dennatology, 96:76s (1991).Ono, et aI., "Histopathological Alteration of Skin after Irra-diation of Ruby Laser", 11(4):99-105 (1991).Oshry, et aI., "Argon Green Laser Photoepilation in theTreatment of Trachomatous Trichiasis", Ophthalmic Plasticand Reconstructive Surgery, 10(4):253-255 (1994).

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US 5,735,844 CI1

EX PARTEREEXAMINATION CERTIFICATE

ISSUED UNDER 35 U.S.C. 307THE PATENT IS HEREBY AMENDED AS

INDICATED BELOW.

AS A RESULT OF REEXAMINATION, IT HASBEEN DETERMINED THAT:

10The patentability of claims 1-3, 6-8, 11, 17-20, 27, 28, 30

and 32 is confirmed.

Claims 12-14 are cancelled.

New claims 33-59 are added and determined to be patent- 15able.

Claims 4, 5, 9, 10, 15, 16, 21-26, 29 and 31 were notreexamined.

33. A method as claimed in claim 32, wherein the elementis a converging element.

34. A method as claimed in claim 33, where in the tissuesurrounding the hair follicles is not significantly damaged.

35. A method as claimed in claim 33, wherein pressure isapplied to the skin surface during the applying step.

36. A method as claimed in claim 35, wherein such pres- 25

sure is positive pressure.37. A method as claimed in claim 35, wherein such pres-

sure is negative pressure.38. A method as claimed in claim 32, 33, 43, 45, 34, 44,

48, 49, 51, 53, 56, 57, or 35, wherein the optical radiation is 30

produced by a laser.39. A method as claimed in claim 38, wherein the laser is

a Nd:YAG laser.40. A method as claimed in claim 38, wherein the laser is

an alexandrite laser.41. A method as claimed in claim 32, 33, 43, 45, 34, 44,

48, 49, 51, 53, 56, 57, or 35, wherein the optical radiation isproduced by a light source producing a wavelength or wave-lengths between 680 and 1200 nanometers.

42. A method as claimed in claim 32, 33, 43, 45, 34, 44,48,49,51,53,56,57, or 35, wherein the method of removalcauses significant permanent hair loss.

243. A method as claimed in claim 32, wherein the element

is a non-converging element.44. A method as claimed in claim 43, where in the tissue

surrounding the hair follicles is not significantly damaged.45. A method as claimed in claim 32, where in the tissue

surrounding the hair follicles is not significantly damaged.46. A method as claimed in claim 45, wherein the wave-

length is between 700-1200 nanometers.47. Method as claimed in claim 46, wherein thefluence is

between 10 and 100 J/ cm2 .

48. A method as claimed in claim 47, wherein a portion ofthe skin region is cooled before the applying step.

49. A method as claimed in claim 48, wherein a portion ofthe skin region is cooled during the applying step.

50. A method as claimed in claim 33, 43, 45, 34, 44, 47,48, or 49, wherein the element is contained within an appli-cator that is in contact with the skin surface during theapplying step.

51. A method as claimed in claim 32, wherein the element20 is contained within an applicator that is in contact with the

skin surface during the applying step.52. A method as claimed in claim 33, 43, 45, 34, 44, 47,

48, 49, or 51, wherein the optical radiation is applied fromair to the skin region.

53. A method as claimed in claim 32, wherein the opticalradiation is applied from air to the skin region.

54. A method as claimed in claim 33, 43, 45, 34, 44, 48,49, 51, or 53, wherein the element includes a transparentsurface.

55. A method as claimed in claim 54, wherein the surfaceis sapphire.

56. A method as claimed in claim 32, wherein the elementincludes a transparent surface.

57. A method as claimed in claim 56, wherein the surface35 is sapphire.

58. A method as claimed in claim 43, 45, 34, 44, 48, 49,51, 53, 56, or 57, wherein pressure is applied to the skinsurface during the applying step.

59. A method as claimed in claim 43, 45, 34, 44, 48, 49,40 51, 53, 56, or 57, wherein such pressure is negative pressure.

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