|Publication number||US20050256515 A1|
|Application number||US 11/148,051|
|Publication date||Nov 17, 2005|
|Filing date||Jun 8, 2005|
|Priority date||Feb 5, 1997|
|Also published as||DE69830732D1, DE69830732T2, EP1011811A1, EP1011811B1, US5810801, US6120497, US6659999, US20040143247, US20080269733, WO1998033558A1|
|Publication number||11148051, 148051, US 2005/0256515 A1, US 2005/256515 A1, US 20050256515 A1, US 20050256515A1, US 2005256515 A1, US 2005256515A1, US-A1-20050256515, US-A1-2005256515, US2005/0256515A1, US2005/256515A1, US20050256515 A1, US20050256515A1, US2005256515 A1, US2005256515A1|
|Inventors||R. Anderson, Edward Ross, James Hsia, Kathleen McMillan|
|Original Assignee||Anderson R R, Ross Edward V Jr, Hsia James C, Mcmillan Kathleen|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (51), Referenced by (4), Classifications (15), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention relates generally to the treatment of wrinkles in human skin using radiation. In particular, the invention relates to a method for treating wrinkles in human skin using a beam of laser or incoherent radiation to cause thermal injury in the dermal region of the skin sufficient to elicit a healing response that produces substantially unwrinkled skin.
Undesired wrinkles in skin are commonly seen in dermatologic practice. Wrinkles in skin may be caused by age and by exposure to the sun's ultraviolet rays. Human skin consists mainly of two layers: the top layer of skin known as the epidermis; and the layer beneath the epidermis known as the dermis. The dermis is primarily acellular and is composed of water, the protein collagen, and glycosaminoglycans. Water constitutes approximately 70 percent of the total weight of the dermis. Collagen constitutes approximately 70 percent of the dry weight of the dermis, and glycosaminoglycans constitute between approximately 0.1 and 0.3 percent of the dry weight of the dermis. Collagen and glycosaminoglycans are constantly produced by fibroblasts, a type of connective tissue cell, and degraded by enzymes. Collagen degradation relies primarily on specific proteinases known as collagenases.
Collagen provides the dermis with the majority of its structural integrity. With aging, the amount of dermal collagen decreases and is replaced by the protein elastin. In addition, the remaining collagen tends to be chaotically oriented as compared to the more organized patterns found in youthful skin. Glycosaminoglycans are very hydrophilic, and increased amounts of these carbohydrates are. associated with the increased skin vigor found in youthful skin. One major difference between the smooth, supple skin of newborns and the drier, thinned skin of older individuals is the far greater relative amount of glycosaminoglycans found in newborn skin. The glycosarninoglycans found in newborns can bind up to 1000 times their weight in water. As the skin ages and the amount of glycosaminoglycans decreases, the skin may become less hydrated and lose some of the suppleness found in youth. Also, the remaining glycosaminoglycans in photo-aged skin are deposited on the haphazardly arranged elastin fibers which have replaced the collagen fibers. The placement of the remaining glycosaminoglycans may partially account for the weather-beaten appearance of photo-aged skin.
Existing procedures for eliminating or reducing the severity of wrinkles include chemical peels, mechanical abrasion and laser ablation. All of these methods remove the top layer of skin. A new top layer forms during healing. Cosmetic improvement is seen when the skin containing wrinkles is replaced by a new layer of horizontally oriented neocollagen in the superficial dermis. However, all of these methods disrupt and completely remove the epidermis. The resulting open wounds require daily care to optimize wound healing. Epidermal destruction and subsequent healing has several undesirable side effects. These undesirable side effects include prolonged hypopigmentation, hyperpigmentation, erythema and edema. Hyperpigmentation occurs frequently in darker skin types as a result ot an inflammatory response of the skin. Hyperpigmentation results in the treated area of the subject's skin turning darker than the surrounding untreated skin. Hyperpigmentation can be slow to clear, sometimes taking up to a year to disappear. Hypopigmentation is attributable to damage to the melanin-producing cells in the skin. While generally transient, hypopigmentation can be permanent,
The present invention addresses the foregoing problems and provides a method for inducing remodeling of the skin's extracellular matrix by partially denaturing the dermal collagen deeper in the skin, below the surface, while avoiding injury to the epidermis and upper layers of the dermis. The invention offers numerous advantages over existing dermatologic procedures and devices. The surface of the skin remains intact, thereby avoiding the need for dressing wounds; pigmentary disturbances are minimized; and any inflammatory response to the injury is mild and less visually evident.
In general, the present invention features a method for treating wrinkles in skin, without removing a layer of skin, using a beam of pulsed, scanned or gated continuous wave (CW) laser or incoherent radiation. The method comprises generating a beam of radiation having a wavelength between 1.3 and 1.8 microns, directing the beam of radiation to a targeted dermal region between 100 microns and 1.2 millimeters below a wrinkle in the skin, and thermally injuring the targeted dermal region to elicit a healing response that produces substantially less wrinkles.
More specifically, causing selective thermal injury to the dermis activates fibroblasts which deposit increased amounts of extracellular matrix constituents (i.e., collagen and glycosaminoglycans). These increases in extracellular matrix constituents are responsible for dermal skin rejuvenation and the reduced appearance of wrinkles.
In one embodiment, the beam of radiation causes partial denaturation of the collagen in the targeted dermal region. The partial denaturation of the collagen accelerates the collagen synthesis process by the fibroblasts and the deposition of new glycosaminoglycans, leading to the elimination or a reduction in the severity of the wrinkle. The method may also include cooling the surface of the skin and epidermal tissue above the targeted dermal region while irradiating the skin. The method may also include cooling the surface of the skin prior to irradiating the skin.
In a detailed embodiment, the method also includes stretching the skin along the wrinkle before directing the beam of radiation to the targeted dermal region below the wrinkle. Stretching the skin causes thermal injury to the collagen fibers across the wrinkle, while not affecting the fibers along the wrinkle.
The invention also relates to an apparatus for treating wrinkles in skin.
The apparatus includes a radiation source and a delivery system which includes a cooling system. The radiation source generates a beam of radiation having a wavelength between 1.3 and 1.8 microns. The delivery system directs the beam of radiation to a targeted dermal region between 100 microns and 1.2 millimeters below a wrinkle in the skin. The cooling system cools the epidermal tissue above the targeted dermal region to minimize injury to the surface of the skin.
The foregoing and other objects, features and advantages of the invention will become apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed on illustrating the principles of the present invention.
The present invention contemplates a system and method for removing wrinkles which includes delivering a beam of laser or incoherent radiation to cause sufficient thermal injury in the dermal region of the skin to elicit a healing response to cause the skin to remodel itself, resulting in more youthful looking (i.e., substantially unwrinkled) skin. In particular, thermal injury may be in the form of partial denaturation of the collagen fibers in the targeted dermal region of skin. In one embodiment, the radiation beam has a set of parameter ranges carefully selected to partially denature collagen in the dermis while protecting the epidermis by surface cooling. As a result, a subject treated using the method of the invention is able to have the appearance of wrinkles lessened without damage to the epidermis.
The beam of radiation is directed to a targeted dermal region of skin between 100 microns and 1.2 millimeters below the wrinkle. The parameter ranges for the beam have been specifically selected to cause thermal injury to the dermis while avoiding injury to the epidermis and upper layers of the dermis. In particular, the wavelength of the radiation beam has been chosen to maximize absorption in the targeted region of the dermis, and the fluence or power density, deperiding on the type of radiation, has been chosen to minimize erythema. The wavelength range chosen has a tissue absorption coefficient preferably in the range of about 1 to 20 cm−1. Thus, the beam preferably has a wavelength of between about 1.3 and 1.8 microns in one embodiment. Within this wavelength range, radiation energy applied through the surface of the skin is deposited predominantly in the dermal region of the skin. In one embodiment, the radiation beam has a nominal wavelength of approximately 1.5 microns. Lasers which produce radiation having wavelengths in the range of between about 1.3 and 1.8 microns include the 1.33 micron Nd:YAG laser, the 1.44 micron Nd:YAG laser and the 1.54 micron Er:Glass laser. The radiation beam may be pulsed, scanned or gated continuous wave laser radiation. In embodiments having a laser as the radiation source 12, the laser radiation generated preferably has a fluence of between about 10 and 150 joules.
In aaother embodiment, the radiation used to thermally injure the dermis is incoherent radiation. In embodiments using incoherent radiation, the incoherent radiation generated by the radiation source 12 preferably has a power density of between about 5 and 100 watts per square centimeter.
To minimize thermal injury to the epidermis and the upper layers of the dermis, in one embodiment, the delivery system 13 includes a cooling system for cooling the surface of the skin prior to and/or during application of the radiation. In this embodiment, the delivery system 13 is multi-functional and is capable of delivering radiation and cooling the surface of the skin at the same time.
In another embodiment, the delivery system 13 and the cooling system are separate systems. The cooling system may comprise a container of a cold fluid. Cooling of the surface of the skin is accomplished by briefly spraying the skin with the cold fluid which extracts heat from the skin on contact. The fluid used can also be a non-toxic substance with high vapor pressure at normal body temperature, such as a freon. These fluids extract heat from the skin by the virtue of evaporative cooling.
The skin contacting portion 20 preferably cools the area of the skin above the targeted dermal region to temperatures below approximately 50 to 70 degrees Celsius during application of the radiation, so as not to cause collateral thermal damage to the epidermis. The radiation beam, due to its wavelength, does not sufficiently penetrate into depths below the targeted dermal region to cause thermal damage deeper in the skin. In one detailed embodiment, the skin contacting portion 20 cools an area of the skin above the targeted dermal region before the radiation is applied. The relative timing of cooling the surface of the skin to applying radiation depends, in part, on the depth to which thermal injury is to be prevented. Longer periods of cooling prior to the application of radiation allow more time for heat to diffuse out of the skin and cause a thicker layer of skin to be cooled, as compared to the thickness of the layer cooled by a short period of cooling. This thicker layer of cooled tissue sustains less thermal injury when the radiation energy is subsequently applied. Continued cooling of the surface of the skin during the delivery of radiation energy extracts heat from the upper layers of the skin as heat is deposited by the radiation, thereby further protecting the upper layers from thermal injury.
The depth of thermal injury caused by the radiation depends primarily on the penetration depth of the radiation used. The penetration depth can be approximated by taking the reciprocal of the absorption coefficient of the skin at the wavelength of the radiation. The thickness of the tissue overlying the zone of injury which is spared from injury depends primarily on the cooling applied prior to and/or during the delivery of radiation energy. By suitably choosing the radiation wavelength, the timing of the surface cooling, the cooling temperature, the radiation fluence and/or the power density as described above, the depth, the thickness and the degree of thermal injury can be confined to a zone within the dermis. These parameters can be chosen to optimally induce the injury required to elicit remodeling within the dermis, while substantially or completely sparing injury to the overlying epidermis and upper layers of the dermis.
In another detailed embodiment, the region of skin including the wrinkle 30 is stretched along the wrinkle 30 before the beam of radiation is directed to the targeted dermal region below the wrinkle 30. Stretching the skin along the wrinkle before irradiating the skin causes partial denaturation of the collagen fibers across the wrinkle, while not damaging the fibers along the wrinkle. Partially denaturing the fibers across the wrinkle tightens the skin sufficiently to cause the wrinkle to disappear.
The method of the present invention for treating wrinkles in skin using radiation was applied in a series of in vivo experiments performed on pigs. A pulsed erbium glass laser producing radiation having a wavelength of approximately 1.54 microns was used as the radiation source 12. The laser energy was applied to the pig skin via the skin contacting portion 20 equipped with a cooled sapphire window 26 at the tip, as described above and shown in
The tip of the skin contacting portion 20 was placed in contact with the skin to cool the skin prior to applying the laser radiation. After a set amount of time (hereinafter “the pre-cooling time”), laser energy was applied to the skin. Various combinations of pre-cooling times, laser pulse energies, laser pulse repetition frequencies, time intervals of laser energy delivery, and total nwnber of laser pulses delivered were studied. It was found that by the appropriate choice of these parameters, varying degrees of thermal injury can be achieved at varying depths in the dermis while preserving the viability of the epidermis and upper dermis.
For example, using a pre-cooling time of 5 seconds, a laser energy in the range of between 0.2 and 0.8 joules per pulse at a pulse repetition frequency of 4 Hertz (corresponding to an average laser power in the range between 0.8 to 3.2 watts), and a total of 24 pulses, it was found that varying degrees of thermal injury could be induced in a zone centered at a depth in the range of approximately 0.5 to 1.0 millimeters beneath the surface of the skin, while avoiding injury to the epidermis and upper dennis.
Histology performed on biopsy samples taken at sites treated with the above range of parameters revealed collagen denaturation extending from about 100 microns in the dermis to about 1 mm deep. The epidermis and upper layers of the dermis were preserved as confirmed with nitrotetrazolium blue, a viability stain. In the cases in which only partial collagen denaturation was shown on histology, clinically, the treated areas showed an intact epidermis with mild edema and erythema which resolved completely within two weeks. Histologically, the treated sites showed greatly increased fibroblast activity, new collagen secretion and degradation of denatured collagen. By four weeks post treatment, the treated sites returned to normal, both clinically and histologically.
While the invention has been particularly shown and described with reference to specific embodiments, it should be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US3404350 *||Jun 2, 1964||Oct 1, 1968||Arthur M. Muncheryan||Directed-beam portable laser system|
|US3538919 *||Apr 7, 1967||Nov 10, 1970||Gregory System Inc||Depilation by means of laser energy|
|US3693623 *||Dec 25, 1970||Sep 26, 1972||Gregory System Inc||Photocoagulation means and method for depilation|
|US3834391 *||Jan 19, 1973||Sep 10, 1974||Block Carol Ltd||Method and apparatus for photoepilation|
|US3900034 *||Apr 10, 1974||Aug 19, 1975||Us Energy||Photochemical stimulation of nerves|
|US3916143 *||Oct 28, 1971||Oct 28, 1975||Research Corp||Branding living animals|
|US4388924 *||May 21, 1981||Jun 21, 1983||Weissman Howard R||Method for laser depilation|
|US4461294 *||Jan 20, 1982||Jul 24, 1984||Baron Neville A||Apparatus and process for recurving the cornea of an eye|
|US4608978 *||Sep 26, 1983||Sep 2, 1986||Carol Block Limited||Method and apparatus for photoepiltion|
|US4617926 *||Jan 30, 1984||Oct 21, 1986||Sutton A Gunilla||Depilation device and method|
|US4733660 *||Dec 10, 1986||Mar 29, 1988||Medical Laser Research And Development Corporation||Laser system for providing target specific energy deposition and damage|
|US4819669 *||Apr 1, 1986||Apr 11, 1989||Politzer Eugene J||Method and apparatus for shaving the beard|
|US4930504 *||Nov 13, 1987||Jun 5, 1990||Diamantopoulos Costas A||Device for biostimulation of tissue and method for treatment of tissue|
|US4976709 *||Jun 30, 1989||Dec 11, 1990||Sand Bruce J||Method for collagen treatment|
|US5000752 *||Jun 19, 1989||Mar 19, 1991||William J. Hoskin||Treatment apparatus and method|
|US5019034 *||Mar 30, 1989||May 28, 1991||Massachusetts Institute Of Technology||Control of transport of molecules across tissue using electroporation|
|US5059192 *||Apr 24, 1990||Oct 22, 1991||Nardo Zaias||Method of hair depilation|
|US5139495 *||Jan 12, 1990||Aug 18, 1992||S. L. T. Japan Co., Ltd.||Bent and tapered laser light emitting probe|
|US5182857 *||Oct 29, 1990||Feb 2, 1993||U.S. Philips Corp.||Shaving apparatus|
|US5226907 *||Oct 29, 1991||Jul 13, 1993||Tankovich Nikolai I||Hair removal device and method|
|US5282797 *||May 28, 1991||Feb 1, 1994||Cyrus Chess||Method for treating cutaneous vascular lesions|
|US5290273 *||May 25, 1993||Mar 1, 1994||Tan Oon T||Laser treatment method for removing pigement containing lesions from the skin of a living human|
|US5304170 *||Mar 12, 1993||Apr 19, 1994||Green Howard A||Method of laser-induced tissue necrosis in carotenoid-containing skin structures|
|US5320618 *||Apr 9, 1991||Jun 14, 1994||Morgan Gustafsson||Device for treatment of undesired skin disfigurements|
|US5336217 *||Jun 5, 1992||Aug 9, 1994||Institut National De La Sante Et De La Recherche Medicale (Insepm)||Process for treatment by irradiating an area of a body, and treatment apparatus usable in dermatology for the treatment of cutaneous angio dysplasias|
|US5344418 *||Dec 12, 1991||Sep 6, 1994||Shahriar Ghaffari||Optical system for treatment of vascular lesions|
|US5397327 *||Jul 27, 1993||Mar 14, 1995||Coherent, Inc.||Surgical laser handpiece for slit incisions|
|US5405368 *||Oct 20, 1992||Apr 11, 1995||Esc Inc.||Method and apparatus for therapeutic electromagnetic treatment|
|US5425728 *||Jan 19, 1993||Jun 20, 1995||Tankovich; Nicolai I.||Hair removal device and method|
|US5445634 *||Sep 29, 1994||Aug 29, 1995||Keller; Gregory S.||Method of laser cosmetic surgery|
|US5474549 *||Feb 18, 1993||Dec 12, 1995||Laserscope||Method and system for scanning a laser beam for controlled distribution of laser dosage|
|US5486172 *||Jan 31, 1994||Jan 23, 1996||Chess; Cyrus||Apparatus for treating cutaneous vascular lesions|
|US5522813 *||Sep 23, 1994||Jun 4, 1996||Coherent, Inc.||Method of treating veins|
|US5527350 *||Feb 24, 1993||Jun 18, 1996||Star Medical Technologies, Inc.||Pulsed infrared laser treatment of psoriasis|
|US5569242 *||Feb 16, 1995||Oct 29, 1996||Lax; Ronald G.||Method and apparatus for controlled contraction of soft tissue|
|US5606798 *||Mar 10, 1992||Mar 4, 1997||Kelman; Elliot||Hair cutting apparatus|
|US5643706 *||Nov 30, 1995||Jul 1, 1997||Xerox Corporation||Process for preparing electroconductive members|
|US5647866 *||May 14, 1996||Jul 15, 1997||Zaias; Nardo||Method of hair depilation|
|US5683380 *||Mar 29, 1995||Nov 4, 1997||Esc Medical Systems Ltd.||Method and apparatus for depilation using pulsed electromagnetic radiation|
|US5707403 *||Apr 23, 1996||Jan 13, 1998||Star Medical Technologies, Inc.||Method for the laser treatment of subsurface blood vessels|
|US5752948 *||Jun 19, 1995||May 19, 1998||Thermolase Corporation||Hair removal method|
|US5752949 *||May 13, 1996||May 19, 1998||Thermolase Corporation||Hair removal method|
|US5755753 *||May 5, 1995||May 26, 1998||Thermage, Inc.||Method for controlled contraction of collagen tissue|
|US5860967 *||Jul 21, 1993||Jan 19, 1999||Lucid, Inc.||Dermatological laser treatment system with electronic visualization of the area being treated|
|US5868732 *||Oct 9, 1996||Feb 9, 1999||Esc Medical Systems, Ltd.||Cooling apparatus for cutaneous treatment employing a laser and method for operating same|
|US5897549 *||Jul 11, 1996||Apr 27, 1999||Lumedics, Ltd.||Transformation of unwanted tissue by deep laser heating of water|
|US5925035 *||Aug 1, 1996||Jul 20, 1999||Thermolase Corporation||Hair removal method|
|US5964749 *||Sep 15, 1995||Oct 12, 1999||Esc Medical Systems Ltd.||Method and apparatus for skin rejuvenation and wrinkle smoothing|
|US6083217 *||Oct 14, 1997||Jul 4, 2000||Lumedics, Ltd.||Destruction for unwanted tissue by deep laser heating of water|
|US6267771 *||Feb 27, 1996||Jul 31, 2001||Thermotrex Corporation||Hair removal device and method|
|US6280438 *||Aug 18, 1997||Aug 28, 2001||Esc Medical Systems Ltd.||Method and apparatus for electromagnetic treatment of the skin, including hair depilation|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7891362||Dec 22, 2006||Feb 22, 2011||Candela Corporation||Methods for treating pigmentary and vascular abnormalities in a dermal region|
|US8246611||Jun 14, 2007||Aug 21, 2012||Candela Corporation||Treatment of skin by spatial modulation of thermal heating|
|US8277495||Sep 16, 2005||Oct 2, 2012||Candela Corporation||Method and apparatus for treating a diseased nail|
|US9028469||Sep 28, 2006||May 12, 2015||Candela Corporation||Method of treating cellulite|
|U.S. Classification||606/9, 607/89, 607/88|
|International Classification||A61B17/00, A61N5/067, A61B18/20, A61B18/00|
|Cooperative Classification||A61B2018/00452, A61B2018/0047, A61N2005/067, A61B2018/00023, A61B2018/00029, A61B2017/00761, A61B18/203|
|Jun 6, 2006||AS||Assignment|
Owner name: CANDELA CORPORATION, MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HSIA, JAMES C.;MCMILLAN, KATHLEEN;REEL/FRAME:017746/0923;SIGNING DATES FROM 19961231 TO 19970114
Owner name: NAVY, UNITED STATES OF AMERICA, THE, AS REPRESENTE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ROSS, JR., EDWARD V.;REEL/FRAME:017746/0932
Effective date: 19970207
Owner name: GENERAL HOSPITAL CORPORTATION, MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ANDERSON, R. ROX;REEL/FRAME:017746/0929
Effective date: 19981015
|Dec 19, 2006||AS||Assignment|
Owner name: CANDELA CORPORATION, MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY OF THE NAVY;REEL/FRAME:018645/0948
Effective date: 20061215