U.S. patent application number 09/981077 was filed with the patent office on 2002-04-18 for wrinkle reduction.
Invention is credited to Clement, Robert Marc, Kiernan, Michael.
Application Number | 20020045891 09/981077 |
Document ID | / |
Family ID | 26309944 |
Filed Date | 2002-04-18 |
United States Patent
Application |
20020045891 |
Kind Code |
A1 |
Clement, Robert Marc ; et
al. |
April 18, 2002 |
Wrinkle reduction
Abstract
Wrinkles are cosmetically removed from a superficial area of
mammalian skin tissue having an epidermal layer, a basal layer, and
a dermal layer, by irradiating the dermal layer through the basal
layer, the irradiation being selected to be absorbed by a
chromophore in the dermal layer such that collagen present in the
dermal layer is heated, while the basal layer remains intact so as
to substantially inhibit contact of the dermal layer with ambient
air.
Inventors: |
Clement, Robert Marc;
(Pontardawe, GB) ; Kiernan, Michael; (Blackpill,
GB) |
Correspondence
Address: |
RUTAN & TUCKER, LLP
P.O. BOX 1950
COSTA MESA
CA
92628-1950
US
|
Family ID: |
26309944 |
Appl. No.: |
09/981077 |
Filed: |
December 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09981077 |
Dec 27, 2001 |
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09263422 |
Mar 5, 1999 |
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09263422 |
Mar 5, 1999 |
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08919472 |
Aug 28, 1997 |
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Current U.S.
Class: |
606/9 ; 128/898;
606/2 |
Current CPC
Class: |
A61B 2017/00761
20130101; A61B 18/203 20130101; A61B 2018/00452 20130101; A61N
5/067 20210801; A61B 2018/0047 20130101 |
Class at
Publication: |
606/9 ; 606/2;
128/898 |
International
Class: |
A61B 018/18 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 29, 1996 |
GB |
9618051.8 |
Claims
1. Apparatus for cosmetic reduction of wrinkles on superficial
mammalian skin, the apparatus comprising a radiation delivery
system for delivering substantially monochromatic radiation, said
radiation being in a wavelength bandwidth of substantially 15 nm or
less and in at least one of the ranges 570 nm to 600 nm and 750 nm
to 850 nm, the delivery system including a pulsation system for
pulsing the radiation delivered according to a predetermined regime
in which the radiation delivered to the skin has an energy density
substantially in the range 0.5 J/cm.sup.2 to 5 J/cm.sup.2 per
pulse.
2. Apparatus according to claim 1, wherein the radiation delivery
system is set up to deliver the substantially monochromatic
radiation in a bandwidth of substantially 15 nm or less
substantially in at least one of the ranges 577 nm to 585 nm and
800 nm to 815 nm.
3. Apparatus according to claim 1, wherein the radiation delivery
system is set up to deliver radiation in a concentrated beam having
a cross-section with a substantially uniform energy distribution
across said beam cross section.
4. Apparatus according to claim 1, wherein the radiation delivery
system is set up to deliver radiation in a concentrated beam having
a diameter substantially in the range 1 mm to 10 mm.
5. Apparatus according to claim 1, wherein the pulsation system is
set up to provide radiation pulses each pulse having a duration
substantially in the range 10 .mu.s to 2 ms.
6. Apparatus according to claim 1, wherein the pulsation system is
set up to provide radiation pulses each pulse having a duration
substantially in the range 200 .mu.s to 1 ms.
7. Apparatus according to claim 1, wherein the radiation delivery
system comprises a laser radiation delivery system.
8. Apparatus according to claim 7, wherein the laser radiation
delivery system comprises a dye laser radiation delivery
system.
9. Apparatus according to claim 8, wherein the dye laser radiation
delivery system comprises a flashlamp pumped dye laser including a
pulse forming network arranged to pulse the laser according to the
predetermined pulse regime.
10. Apparatus according to claim 7, wherein the laser radiation
delivery system comprises a semiconductor laser radiation delivery
system.
11. Apparatus according to claim 1, wherein the radiation delivery
means includes a radiation emitting LED device.
12. Apparatus according to claim 11, wherein the radiation delivery
means includes at least one radiation filter arranged to filter
radiation to permit the substantially monochromatic radiation to be
delivered to the skin.
13. Apparatus according to claim 1, further comprising a control
system arranged to permit the energy density to be varied within
the range 0.5 J/cm.sup.2 and 5 J/cm.sup.2.
14. Apparatus according to claim 13, wherein the control means is
arranged to inhibit selection of an energy density substantially
above 5 J/cm.sup.2.
15. Apparatus for cosmetic reduction of wrinkles on a superficial
area of mammalian skin, the apparatus comprising a radiation
delivery system for delivering a radiation beam of predetermined
monochromatic wavelength or narrow wavelength bandwidth to the
skin, the radiation delivery system including a pulsation system
for pulsing the radiation delivered according to a predetermined
regime such that the total radiation energy density delivered to
the skin is substantially in the range 0.5 J/cm.sup.2 to 5
J/cm.sup.2 per pulse.
16. Apparatus according to claim 15, which includes an optical
arrangement for focussing the beam.
17. A method of cosmetically removing wrinkles from a superficial
area of mammalian skin tissue having, in the order specified, an
epidermal layer, a basal layer, and a dermal layer, which method
comprises: irradiating said dermal layer through said basal layer
by means of visible or infra-red radiation, said irradiation being
selected to be absorbed by a chromophore in said dermal layer such
that collagen present in said dermal layer is heated, while said
basal layer remains intact so as to substantially inhibit contact
of said dermal layer with ambient air.
18. A method according to claim 17, wherein the irradiation is from
a substantially monochromatic radiation source in a bandwidth of
substantially 15 nm or less.
19. A method according to claim 17, wherein said irradiation is
from a coherent radiation source.
20. A method according to claim 17, wherein the source comprises a
ruby laser arranged to target the dermis.
21. A method according to claim 17, wherein the source comprises a
dye laser of wavelength selected to target oxyhemoglobin present in
blood vessels in said dermal layer.
22. A method according to claim 17, wherein the source comprises a
dye laser, a ruby laser, or a semiconductor laser which scans said
area of mammalian skin tissue.
23. A method according to claim 22, wherein the laser comprising
said source is pulsed.
24. A method according to claim 23, wherein the pulsed laser has
pulses of duration 10 .mu.sec to 2 msec.
25. A method according to claim 17, in which said superficial area
of mammalian skin tissue is treated with an artificial chromophore
which is absorbed into the dermal layer.
26. A method according to claim 25, wherein the artificial
chromophore is applied to the epidermal layer in the form of a
liposome-containing topical formulation.
Description
[0001] This is a Continuation In Part of U.S. patent application
Ser. No. 08/919,472 Filed on Aug. 28, 1997.
BACKGROUND TO THE INVENTION
[0002] The present invention relates to a method of reducing
wrinkles from a superficial area of mammalian skin tissue, and
apparatus therefor.
[0003] The application of laser technology in healthcare is well
known, and the use of lasers in medical applications has been
studied extensively since the early 1960's. In recent years an
increasing interest has been shown in cosmetic applications. Two
such cosmetic applications are skin resurfacing and wrinkle
removal; in this field lasers can be used as an alternative to
surgical facelifts.
[0004] There is a distinct difference between wrinkle removal and
skin resurfacing. Skin resurfacing is where laser energy vaporizes
thin layers of the epidermis without breaking through the basal
layer into the dermis. This is essentially a superficial process
primarily used to give the skin a "fresher" appearance. However,
wrinkle removal as a more aggressive technique where tissue is
removed layer by layer, invading the dermis and effectively
inducing a second degree burn. Heat is deposited in the dermis
shrinking the collagen and tightening the skin.
[0005] In young skin, the collagen just beneath the surface of the
skin forms an organized lattice with good elasticity and
flexibility. During aging, the collagen changes its structure
impacting negatively on the cosmetic appearance of the skin.
Several techniques have been developed to induce a "controlled
injury" to the dermis in an attempt to generate rejuvenation of the
collagen structure returning the skin to an earlier cosmetic
appearance. During the 1990's a laser approach to wrinkle removal
has been introduced.
[0006] For known wrinkle removal techniques, the wavelength is
chosen so that the laser energy is highly absorbed in water, the
current lasers of choice being the CO.sub.2 laser at 10.6 .mu.m
wavelength and the Erbium YAG laser at 2.94 .mu.m wavelength. In
this non-selective process, pulses of laser energy are applied to
the skin surface, each pulse vaporizing a layer of tissue between
30 .mu.m to 60 .mu.m in thickness. Normally, the first pass of the
laser removes a thin layer of the epidermis without damaging the
basal layer. Successive passes over the same area penetrate into
the dermis and heat the collagen. The laser operator sees this
thermal build-up "shrink" the skin in "real time", tightening up
the skin's appearance. When the desired clinical outcome is
achieved, the operator ceases applying laser pulses. It is
therefore apparent that the quality of the cosmetic result is
highly dependent upon the experience and skill of the operator.
[0007] In the case of CO.sub.2 laser wrinkle removal,
post-treatment supervision of the patient is a necessity.
Immediately after treatment, the skin is essentially an open wound
requiring dressings in place for 2-10 days. Additionally, topically
applied lotions are required for patient comfort and prevention of
infection. Post-operative infection is common, primarily due to
removal of the natural protective barrier of the skin, with a
reported incidence of between 4.5 to 7%.
[0008] On average, with CO.sub.2 laser wrinkle removal,
post-treatment erythema is present for 4-5 months. This compares to
2-3 months following a Chemical Peel. Also, the incidence of side
effects is significant, the most common being hyperpigmentation
occurring in 30-40% of cases. Higher incidences are reported in
darker skin types. A delayed hypopigmentation, which can occur up
to a year after the procedure was performed, has recently emerged
as a complication of aggressive laser resurfacing. Many of the
eminent laser resurfacing surgeons have resorted to less aggressive
techniques.
[0009] The effect of known procedures is two fold:
[0010] (a) the laser induces denaturing of the collagen in the
dermis, and the formation of cross links, which results in a
tightening effect stretching the skin, reducing or removing the
wrinkles (it is thought that the thermal threshold for this effect
is a temperature of 70.degree. C.); and
[0011] (b) the changes to the dermis induce the generation of new
collagen which develops using the matrix created by the denatured
collagen as a foundation.
[0012] The skin-resurfacing and wrinkle removal procedure outlined
above is considered by many experts in the field as a significant
improvement over previously used surgical methods. The procedure
uses the laser's ability to deliver high energy density at the
surface of tissue and hence ablate the surface tissue in a well
controlled manner. Continuing to remove the tissue, layer by layer
is designed to damage the collagen and hence induce wrinkle
removal. This second stage of the procedure is primitive; the skin
weeps, scabs form and redness of the skin appears for many
weeks.
OBJECT OF THE INVENTION
[0013] It is therefore the primary object of the present invention
to provide a technique for removing wrinkles from a superficial
area of mammalian skin tissue without causing secondary burns and
other problems associated with traditional wrinkle removal.
SUMMARY OF THE INVENTION
[0014] The present invention provides a method of removing wrinkles
from a superficial area of mammalian skin tissue. The dermal layer
of the tissue is irradiated through the basal layer by radiation
selected to be absorbed by a chromophore in the dermal layer such
that collagen present in the dermal layer is heated, while the
basal layer remains intact so as to substantially inhibit contact
of the dermal layer with ambient air.
[0015] According to a further aspect, the invention provides
apparatus for cosmetic reduction of wrinkles on a superficial area
of mammalian skin, the apparatus comprising a radiation delivery
system for delivering a radiation beam of predetermined
monochromatic wavelength or narrow wavelength bandwidth to the
skin, the radiation delivery system including a pulsation system
for pulsing the radiation delivered according to a predetermined
regime, and an optical arrangement for focussing the beam such that
the total radiation energy density delivered to the skin is
substantially in the range 0.5 J/cm.sup.2 to 5 J/cm.sup.2 per
pulse.
[0016] The irradiation of the dermal layer in the method according
to the invention is tailored to shrink the skin tissue without
damage to the dermis (in other words, without causing second degree
burns) because the barrier provided by the basal layer remains
intact. This is achieved by selecting the required radiation
wavelength to match the characteristic absorbtion wavelength of the
chromophore whilst being absorbed to an insignificant degree in the
epidermis and basal layer. The energy delivered per pulse is also
tailored to ensure that ablation does not occur of the target
structure, but rather that energy absorbed in the target provides
sufficient heating that heat energy diffusing outwards from the
target heats the surrounding tissues to a degree sufficient to
thermally induce shrinkage of the surrounding tissue and also
stimulate the production of new tissue components such as elastin
and collagen.
[0017] If the target for the laser has an appropriate chromophore
(a substance that absorbs a specific wavelength and transmits or
scatters at other wavelengths) then the laser can be used to modify
that target selectively within an inhomogeneous volume of tissue.
Occasionally, the desired target does not have a suitable
chromophore of its own but exists in close proximity to another
material which has such a chromophore which can be selectively
targeted. Such interaction is called secondary selective
interaction.
[0018] An artificial chromophore may be introduced into the desired
area for wrinkle reduction, or a naturally occurring chromophore
may be selected. In a preferred embodiment of the technique, the
naturally occurring chromophore selected is oxyhemoglobin of the
dermal plexus which has wavelength absorbtion peaks at 585 nm and
815 nm, at which wavelengths absorbtion in surrounding tissue
components is relatively low.
[0019] According to a further aspect, the invention therefore
provides apparatus for cosmetic reduction of wrinkles on a
superficial area of mammalian skin, the apparatus comprising a
radiation delivery system for delivering substantially
monochromatic radiation in a bandwidth of substantially 15 nm or
less in at least one of the ranges 570 nm to 600 nm and 750 nm to
850 nm, the delivery system including a pulsation system for
pulsing the radiation delivered according to a predetermined regime
in which the energy density of the substantially monochromatic
radiation in the bandwidth of substantially 15 nm or less delivered
to the skin is substantially in the range 0.5 J/cm.sup.2 to 5
J/cm.sup.2 per pulse.
[0020] The method according to the invention is non-invasive and
non-ablative and can readily be performed by non-medical personnel.
The total energy delivered per pulse is sufficient to effect the
required physical change in the tissue surrounding the target
chromophore without causing ablation of the target or other skin
components through which the radiation passes.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0021] The radiation is preferably substantially monochromatic or
at least of a relatively narrow wavelength bandwidth to ensure that
it is preferentially selectively absorbed by the target
chromophore. A laser source may be used to produce the required
wavelength, or a light source, such as an LED may be used with
appropriate filtering to permit the selected wavelength (or narrow
wavelength band) to pass.
[0022] The irradiation may be by means of a source of visible or
infra-red radiation (suitably filtered to remove deleterious
ultra-violet radiation if necessary). The radiation may be coherent
(that is from a laser source). Such a laser source may be, for
example, a dye laser, a ruby laser, or a semiconductor laser. If a
dye laser is used, its wavelength is preferably such that it is
absorbed by oxyhemoglobin (as naturally occurring chromophore
present in blood vessels in the dermis). Alternatively, the
superficial area may be treated with an artificial chromophore
which is absorbed into the dermal layer. Such an artificial
chromophore may be applied to the epidermal layer in the form of a
liposome-containing topical formulation. The chromophore may then
permeate through the basal layer for delivery to the dermal
layer.
[0023] When a laser is used, it may be arranged to scan the
superficial area and/or to irradiate the dermal layer in pulses.
When the laser is in pulsed mode, the pulses typically have
duration of 10 .mu.sec to 10 msec (more preferably 200 .mu.sec to 1
msec).
[0024] It is sometimes desirable to remove part of the epidermis
prior to irradiating the dermal layer according to the invention.
Such epidermis removal (known as skin resurfacing) may be effected
mechanically (for example by abrasion), or by means of laser
radiation. When laser radiation is used for this purpose, it is
typically a scanner controlled CO.sub.2 laser source.
[0025] The energy density per pulse is preferably accurately
controlled to ensure that a maximum threshold level (substantially
of 5 J/cm.sup.2) is not exceeded.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a schematic representation of the three outermost
layers of mammalian skin tissue;
[0027] FIG. 2 is a schematic representation of partial removal of
the epidermis (skin resurfacing), which is an optional step
according to the invention;
[0028] FIG. 3 is a schematic illustration of the result of a prior
art method of wrinkle removal, which is surgical because it
involves full removal of the epidermis in a selected area and
therefore exposure of the dermis and consequent second degree
burning;
[0029] FIG. 4 is a schematic illustration of the result of the
method according to the invention, showing that the epidermis is
partially intact and the basal layer fully intact;
[0030] FIG. 5, is a schematic diagram of a first embodiment of
wrinkle reduction apparatus according to the invention;
[0031] FIG. 6 is a schematic diagram of an alternate embodiment of
wrinkle reduction apparatus according to the invention;
[0032] FIG. 7 is a schematic representation of an optical delivery
system forming part of apparatus according to the invention;
and,
[0033] FIG. 8 is a graphical representation showing the intensity
profile of the radiation delivered using apparatus according to the
invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0034] Referring to FIG. 1, the basic skin structure of mammalian
skin tissue comprises three layers, the outermost epidermis 1 which
is adjacent to the basal layer 2 and then the dermis 3.
[0035] Referring to FIG. 2, partial removal of an area 4 of
epidermis 1 by means of CO.sub.2 laser radiation is known as skin
resurfacing. This stage represents the first step of a prior art
method but is an optional step according to the invention. Both the
basal layer 2 and the dermis 3 are unaffected by the laser
radiation.
[0036] As shown in FIG. 3, prior art method of wrinkle removal
results in complete removal of an area 5 of epidermis 1 and basal
layer 2 by repeated exposure to CO.sub.2 laser radiation. Partial
removal of the dermis 3 also occurs, as represented by 6, leaving
the dermis exposed to air. This causes a second degree burn which
is slow to heal and a risk of infection.
[0037] As shown in FIG. 4, the method of wrinkle removal according
to the invention results in partial removal of the epidermis 1
(this is an optional step as described in FIG. 2 above) and the
basal layer 2 is left intact, such that the dermis 3 is not exposed
to air. Laser radiation 7 is applied to the tissue and selectively
absorbed by a chromophore in the dermis 3, heating the collagen and
shrinking the skin hence removing the appearance of wrinkles.
[0038] In a preferred embodiment, the target chromophore selected
is oxyhemoglobin in the dermis 3 which has absorbtion peaks at
approximately 585 nm and 815 nm. The apparatus shown in FIG. 5
comprises a laser radiation delivery system 101 comprising a
flashlamp excited pumped dye laser including a laser head 102, dye
reservoir 103 and pump 104. A flowmeter 105 regulates dye flow to
the laser cavity in the laser head 102 and a cooling system 106
cools the laser head 102 and dye reservoir 103. The system is
controlled by a microprocessor controller 107 which operates
voltage control of a pulse forming network 108 (including a
capacitor and inductor network) which initiates a discharge pulse
and consequently a pulsed beam laser output from laser head 102.
Voltage control and feedback is provided between the microprocessor
controller 107 and pulse forming network 108 via link 109.
Temperature monitoring feedback is provided between the cooling
system and the controller 107 via link 110.
[0039] The laser head operates to output controlled pulses of laser
radiation having wavelength in the range 577 nm to 585 nm and a
pulse duration in the range 200 .mu.s to 1 ms. To produce the
required wavelength an appropriate laser dye is selected (such as
Rhodamine 575 or Pyromethene 590), the concentration of the dye
solution is controlled.
[0040] Control of the pulse duration for the dye laser arrangement
101 is achieved by accurate control of the energy delivered to the
exciting flashlamps in the laser head 102 by tailoring the
capacitor and inductor values in the pulse forming network 108.
[0041] The energy is delivered to the skin surface via a fiberoptic
tube 112 (see FIG. 7) and a focussing optical lens arrangement 113
which is configured to focus a light spot onto the skin tissue
surface so as to have a spot diameter within the range 1 mm to 10
mm, and an intensity distribution across the spot diameter that is
substantially uniform (i.e. "a top hat" distribution), as shown in
FIG. 8. Providing optics to ensure that the uniform energy
distribution results in even heating of the tissue without the
occurrence of "hot spots" which could result in tissue
damage/oblation.
[0042] The radiation parameters are also selected to ensure that
the total radiation energy density delivered per pulse falls within
the range 0.5 J/cm.sup.2 to 5 J/cm.sup.2. It is particularly
important that the selected upper threshold value (5 J/cm.sup.2) is
not exceeded significantly as delivery of a higher energy densities
of radiation per pulse can result in unwanted effects on the skin
(such as ablation and/or other damage).
[0043] For the dye laser system 101 of FIG. 1, the energy density
of the radiation delivered to the skin is controlled by adjustment
of the flashlamp output energy (which in turn controls the laser
output energy). The laser output energy in conjunction with the
spot site determines the energy density delivered. Accurate control
is achieved by control of the dye circulation rate, the dye
temperature and the flashlamp output energy. Dye circulation rate
is important because repeated pulsing of the same volume of dye,
without circulation, reduces the output energy of the laser head
102. Increasing or decreasing the dye temperature has an affect on
the energy output of the laser head 102. The flashlamp output
energy is controlled by varying the voltage with which the
capacitors in the pulse forming network 108 are charged; feedback
of the capacitor voltage via link 109 is therefore important.
[0044] The energy density required will vary within the specified
range from person to person, depending upon skin colour.
[0045] Referring to FIG. 6, there is shown an alternative
embodiment of apparatus for performance of the invention in which
an LED or semiconductor laser device 202 may be utilised to produce
the output radiation 220. A user interface 213 enables input into a
microprocessor controller 207 which is used to control a power
supply unit 214 to ensure that the required current is supplied to
the LED or semiconductor laser device 220. A temperature sensor 215
provides temperature feedback via a link 210. Output 216 from
controller 207 sets the current supplied by the power supply unit
214 to the device 202; input 217 into the controller 207 provides
current monitoring feedback. Control of the pulse duration is
achieved by pulsing the current supply from power supply unit 214
to the LED or semiconductor laser device 202.
[0046] High intensity LED devices are capable of producing
wavelengths corresponding to the 585 nm absorption peak of
oxyhaemoglobin. The optical system (including lens 113) may include
filters arranged to narrow the band of radiation passing from the
LED to the target area of the skin. Where lasers are used, the
output may be monochromatic. Alternatively, or in the case where
LED's are used, the radiation delivered may be "effectively"
monochromatic, or of a relatively narrow band width (typically
within a band width of 15 nm or less).
[0047] Where a semiconductor laser device is used, the output may
correspond to the second (higher) absorption peak (815 nm) for
oxyhaemoglobin.
[0048] Whilst the invention has been described in relation to
delivery of effectively monochromatic radiation (or within specific
narrow band widths) at one or other of the oxyhaemoglobin
absorption peaks of 585 nm and 815 nm, it is clear that the
beneficial effect of the invention can be achieved to a certain
degree by using wavelengths relatively close to, but either side,
of the respective absorption peaks. Preferred wavelength ranges for
operation are 570 nm to 600 nm and 750 nm to 850 nm for targeting
oxyhaemoglobin.
[0049] Where an artificial chromophore is used, the wavelength (or
narrow band of wavelengths) is selected to correspond to a
characteristic absorption wavelength of the relevant chromophore.
It remains important to ensure that the total energy delivered per
pulse is below the threshold damage level (approximately 5
J/cm.sup.2).
[0050] In the embodiments described, it is important to ensure that
there is not excess energy (and therefore heat) build-up in the
target, and therefore the inter pulse duration is selected at a
level to avoid this situation occurring. It is preferred that the
pulse repetition rate is substantially in the range 3 Hz maximum or
less.
* * * * *