Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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APARATUS AND METHOD FOR TREATMENT OF SKIN CONDITIONS USING LIGHT
The present invention relates to an apparatus and
method for the treatment of a skin condition or for
improving the cosmetic appearance of skin. In particular,
the invention relates to an apparatus and a method for the
treatment of Acne Vulgaris.
Acne Vulgaris is a skin condition which affects almost
1000 of the population at some point in their lives. 1t is
a condition of the sebaceous follicles (pores) and can lead
to lesions on the skin, primarily on the face, shoulders
and back. The symptoms of Acne Vulgaris, and of other
similar skin conditions, can be unsightly and undesirable
25 cosmetically.
Acne Vulgaris is caused by a number of factors, of
which the most significant are believed to be: excessive
hormone production (especially androgens), excessive sebum
production (sebum is an oily substance produced by the
sebaceous glands to keep the skin soft, pliable and
waterproof), excessive dead cell shedding, the presence of
bacteria (particularly Propionibacterium acnes) in the
sebaceous follicles and the bodies inflammatory response
(chemotaxis).
The process starts when dead skin cells and the oily
substance sebum combine to block the skin's sebaceous
follicles. The dead skin and sebum form a plug which traps
oil and bacteria within the sebaceous follicles. The
sebaceous follicle begins to swell as the skin continues
its normal oil production. Normal skin bacteria
Propionibacterium acnes multiply rapidly in the clogged
pore. The multiplication of the bacteria produces
substances which cause inflammation in the follicle and
surrounding skin. The body's response is to send white
blood cells to the inflamed areas.
The lesions range in severity and can be defined as
come.dones, papules, nodules, pustules and cysts. Comedones
are sebaceous follicles that have become blocked. Papules
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are small (less than 5mm) solid lesions slightly above the
surface of the skin. Nodules are larger papules (greater
than 5mm). Pustules are dome shaped fragile lesions
typically containing a mixture of white blood cells, dead
cells and bacteria. Cysts are similar to pustules but are
larger and are severely inflamed and often lead to
scarring.
Various drug treatments are known to be at least
partially effective in preventing Acne Vulgaris.
A treatment for Acne Vulgaris using light radiation is
disclosed in GB 2 368 020. In the embodiments disclosed,
radiation is provided at specific energy densities and
wavelengths in order to cause photo-chemical and photo-
thermal reactions in the skin. The photo-chemical reaction
leads to a partial disabling or eradication of a cause of
the skin condition while the photo-thermal reaction
increases collagen production, thereby helping to reduce
the risk of scarring.
The method disclosed in GB 2 368 020 requires the
provision of relatively high doses of radiation (0.5Jczri2 to
5Jcn12) in short periods of time (l0us to 100ms) in order to
produce the photo-thermal effects in the skin. Providing
these high energy levels over short periods of time
requires high power lasers. These are expensive to
manufacture and operators may be required to have
specialist training and knowledge to use them safely and
effectively.
It is an object of the invention to provide an
apparatus for improving the appearance of the skin, for
example an apparatus for the treatment of a skin condition,
that is relatively inexpensive and/or simple to operate.
It is an alternative or additional object of the invention
to provide a method for improving the appearance of the
skin or for the cosmetic treatment of a skin condition that
is relatively inexpensive andlor simple to carry out.
According to one aspect of the invention there is
provided an apparatus for the treatment of a skin condition
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comprising
an illuminating device, and
a control unit for controlling the operation of the
illuminating device, wherein
the illuminating device is so arranged and configured
that it is able in use to emit light radiation of an energy
and wavelength profile sufficient to cause a photochemical
reaction within an area of skin affected by the skin
condition, which reaction would result in agents causing
the skin condition being at least partially disabled or
destroyed, and
the control unit and illuminating device are so
arranged and configured that the control unit is able in
use to cause the illuminating device to direct light
radiation on to an area within a distance of no more than
1000mm from the illuminating device such that:
the light energy received at said area during a period
of at least 100ms is at least 0.01Jcrri2,
the light energy received at said area in any given
period of 10~,s is less than 0.5 Jcrri ~, and
the light energy so delivered in any given period of
100ms is less than 5 Jcn1 ~, whereby
the apparatus may be used to treat the skin condition.
According to another aspect of the invention there is
provided an apparatus for improving the cosmetic appearance
of the skin of a mammal, for example a human being, the
apparatus comprising
an illuminating device for emitting light radiation,
and
a control unit for controlling the operation of the
illuminating device, wherein
the control unit is so arranged and configured that it
is able in use to cause the illuminating device to direct
light radiation on to an area within a distance of no more
than 1000mm from the illuminating device such that:
the light energy received at said area during a period
of at least 100ms is at least 0.01Jcrri2,
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the light energy received at said area in any given
period of 10~,s is less than 0. 5 Jcrri 2, and
the light energy so delivered in any given period of
100ms is less than 5 Jciri 2, whereby
the apparatus may be used to improve the cosmetic
appearance of the skin. The illuminating device may be so
arranged and configured that it is able, when being used to
direct light onto the skin, to emit light radiation of an
energy and wavelength profile sufficient to cause a
photochemical reaction within an area of the skin being
targeted. The photochemical reaction may be caused in such
a way that it partially disables or destroys agents in the
skin that are causing the cosmetic appearance of the skin
to be worsened.
According to a further aspect of the invention there
is also provided an apparatus for the treatment of Acne
Vulgaris comprising one or more light emitting diodes, and
a microprocessor for controlling the operation of said one
or more light emitting diodes, wherein said microprocessor
and said one or more light emitting diodes are so arranged
and configured that said one or more light emitting diodes
are able in use to deliver a dose of light radiation onto a
surface during a period of at least 100ms, such that the
surface receives during said dose light energy of at least
O.OIJcm'~, the light so delivered including radiation
having a wavelength in the range of 350nm and 700nm,
whereby the apparatus may be used to treat a region of skin
affected by the condition Acne Vulgaris by causing a
photochemical reaction in said region that stimulates the
production of free radicals that react with, and at least
partially disable or destroy, bacteria that contribute to
the symptoms of Acne Vulgaris.
Further optional or preferred features of the
apparatus according to either of the above-mentioned
aspects of the invention are described below.
The apparatus may alternatively or additionally be
suitable for improving the cosmetic appearance of the skin
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of a mammal, for example a human being.
The illuminating device of the apparatus of the
invention may be so arranged and configured that it is
able, when being used to direct light onto the skin, to
emit light radiation of an energy wavelength profile
sufficient to cause a photochemical reaction within an area
of the skin being targeted. The photochemical reaction may
be caused in such a way that it partially disables or
destroys agents in the skin that are causing the cosmetic
appearance of the skin to be worsened.
The illuminating device preferably comprises one or
more light emitting semiconductor devices. The or each
semiconductor device may be in the form of a diode. The
illuminating device may for example comprise one or more
LEDs. LEDs are, advantageously relatively inexpensive and
simple to operate in comparison to lasers. Laser diodes
may additionally or alternatively be used. Conveniently,
the illuminating device is in the form of a device, for
example comprising at least one semiconductor device that
in use acts as the active light emitting element(s), that
has a power input requirement of less than 500W, and
preferably less than 100W, per individual semiconductor
device.
The control unit and illuminating device of the
apparatus may be so configured and arranged that the
control unit is able in use to cause the illuminating
device to deliver light energy of between 0.01 and 100 Jcrri~
to said area during a period of between 200ms and 3
seconds, or more preferably during a period of between
300ms and 2 seconds. Of course, the control unit and
illuminating device may be arranged to emit radiation
during a single treatment over a longer period of time, so
that during a single treatment more than 100 Jcm'a is
delivered over a period of greater than 3 seconds. A
single treatment might last as long as up to 10 hours.
Such a treatment might for example be provided overnight.
Preferably, the control unit and illuminating device of the
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apparatus are so configured and arranged that less than 100
Jcnl2 of light energy is delivered during any period of 3
seconds.
The control unit and illuminating device may be so
configured and arranged that the illuminating device
delivers pulsed light radiation during a single treatment.
Alternatively, the control unit and illuminating device may
be so configured and arranged that the illuminating device
delivers continuous light radiation during a single
treatment. The apparatus may be so configured to be able
to deliver either continuous or pulsed radiation at the
choice of the user.
The control unit and illuminating device of the
apparatus may be so configured and arranged that the
control unit is able in use to cause the illuminating
device to deliver light energy of between 0.5 Jcnl2 and 3
Jciri2 to said area during a period of between 100ms and 100
seconds. The control unit and illuminating device may be
so configured and arranged that the control unit is able in
use to cause the illuminating device to deliver a single
dose of light radiation to an area of skin, the single dose
being provided over a period of between 200ms and 10
seconds (or more preferably between 200ms and 3 seconds)
and the energy of the light radiation delivered during the
single dose being greater than 0.1 Jcni2 and being equal to
T1 x P1, where T1 = the length in time of the single dose
and P1 has the units of optical power density (power per
unit area) and satisfies 0.2Wcrri 2 < P1 < 20Wciri ~.
The apparatus may be in the form of a top up apparatus
allowing lower levels of light energy to be delivered. For
example, the control unit and illuminating device may be so
configured and arranged that the control unit is able in
use to cause the illuminating device to deliver a single
dose of light radiation to an area of skin, the single dose
being provided over a period of between 300ms and 10
seconds (or more preferably between 300ms and 3 seconds)
and the energy of the light radiation delivered during the
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single dose being equal to T~ x P2, where T2 = the length in
time of the single dose and P~ has the units of optical
power density (power per unit area) and satisfies 0.01Wcm ~
< Pa < lWcm'2. P2 may satisfy the condition 0. lWcm 2 < P2 <
0 . 5Wcrri ~ .
The apparatus may be so configured and arranged that
it is suitable for treatment of relatively small areas at a
time. For example, the apparatus may be so configured and
arranged that, during a single dose of light radiation, an
area of skin of between 12 and 200mm2 is treated.
The apparatus may be so configured and arranged that
it is suitable for lower power operation over longer
periods of time. For example, the control unit and
illuminating device may be so configured and arranged that
the control unit is able in use to deliver, during a single
treatment lasting between 300ms and 10 hours (more
preferably between 10 seconds and 8 hours), light radiation
to an area of skin, the energy of the light radiation
delivered during the single treatment being greater than
0.1 Jciri 2 and being equal to T3 x P3, where T3 = the length
in time of the single treatment and P3 has the units of
optical power density (power per unit area) and satisfies
0.5mV~7cni 2 < P3 < 500mWcm ~. The longer treatment may last
for at least 30 seconds, preferably lasts for at least 10
minutes and more preferably lasts for at least an hour.
The apparatus may be so configured and arranged that
it is suitable for treatment of relatively large areas at a
time. For example, the apparatus may be so configured and
arranged that, during a single treatment, an area of skin
of between 0.003m2 and 0.5m2 is treated. Such an apparatus
is preferably arranged such that the energy of the light
radiation delivered during a single treatment is equal to T3
x P3, where T3 = the length in time of the single treatment
and P3 has the units of optical power density tpower per
unit area) and satisfies 0.5mWcn1 2 < P3 < 500mWciri 2.
The illuminating device is preferably arranged to
provide light radiation including radiation having a
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wavelength of between 350nm and 1500nm. The illuminating
device is preferably arranged to emit radiation at a
wavelength between 350nm and 1000nm, more preferably
between 350nm and 700nm. The illuminating device is
preferably arranged to provide light radiation including
radiation having a wavelength between 570nm and 600nm. The
illuminating device may alternatively or additionally be
arranged to provide light radiation of a wavelength between
390nm and 420nm, and preferably includes light radiation
having a wavelength of about 405nm.
The photo-chemical reaction that may be caused by the
apparatus when used to treat the skin may take place in
Porphyrin, which is a naturally occurring substance
produced by the bacteria Propionibacterium acnes. Further
discussion is provided below in relation to a method
according to another aspect of the invention. The Porphyrin
activation spectrum has peaks at both about 585nm and
405nm. Providing light radiation including light having a
wavelength between 390nm and 420nm and including light
having a wavelength between 570nm and 600nm is considered
to be particularly advantageous as such a combination may
activate Porphyrin at different depths in the skin tissue.
Also, it is believed that red light (of a wavelength
between 630nm and 680nm) may aid in the wound healing
process.
The illuminating device is preferably arranged to
provide light radiation having a peak power level of less
than 100Wcni~. More preferably, the illuminating device is
preferably arranged to provide light radiation having a
peak power level of less than lOWcrri2. Even more
preferably, the illuminating device is preferably arranged
to provide light radiation having a peak power level of
less than 5Wcni2. Advantageously, the peak power level is
between about lWcni2 and 5Wcm ~. The peak power level may be
between about lWcm 2 and 3Wciri 2.
The apparatus may include cooling means for
controlling the temperature of the illuminating device.
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The control unit is preferably arranged to control
operation of any such cooling means. The control unit may
conveniently comprise a suitably pre-programmed
microprocessor.
In accordance with the present invention there is also
provided a use of said apparatus including illuminating a
surface within a distance of no more than 1000mm from the
illuminating device with radiation of an energy such that
an area of at least 12mm2 receives energy from the
illuminating device during a period of at least 100ms of at
least 0.01Jciri2, the radiation including radiation having a
wavelength of between 350 and 700nm (preferably including
radiation having a wavelength of between 570 nm and 600 nm
and/or of between 390nm and 420nm), the energy received
from the illuminating device at said area in any given
period of 10~,s being less than 0. 5 Jcrn 2, and the
energy received from the illuminating device in any given
period of 100ms being less than 5 Jcm'2. Said use is
advantageously, but not necessarily, performed to treat a
skin condition on the skin of a human. The use of the
apparatus may for example be in the form of performing a
method of improving the cosmetic appearance of the skin
and/or a method of cosmetic treatment of a skin condition.
The use of the apparatus may for example be in the form of
testing and/or demonstrating the apparatus on a surface
that is, for example, not in the form of the skin of a
living animal or human.
The apparatus of the invention is advantageously so
arranged that the apparatus may be used to treat the skin
of a patient without the need to pre-cool the skin before
treatment.
According to another aspect of the invention there is
provided a method for the treatment of a skin condition
comprising the steps of
providing an illuminating device, and
operating the illuminating device to direct light
radiation on to an area of skin affected by the skin
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condition, wherein
during a single treatment, lasting at least 100ms,
said area receives light energy from the illuminating
device of at least 0. OlJciri 2,
the light energy so delivered in any given period of
10~,s is less than 0.5 Jcrn ~,
the light energy so delivered in any given period of
100ms is less than 5 Jciri 2, and
the light energy so delivered causes a photochemical
reaction within the affected skin which at least partially
disables or destroys agents causing the skin condition.
There is also provided according to another aspect of
the invention a method of improving the cosmetic appearance
of a region of the skin, for example of a mammal,
comprising the steps of
providing an illuminating device, and
operating the illuminating device to direct light
radiation on to the region of skin, wherein
during a period of at least 100ms, said region
receives light energy from the illuminating device of at
least 0. OlJciri ~,
the light energy so delivered in any given period of
10~,s is less than 0.5 Jcrri 2, and
the light energy so delivered in any given period of
100ms is less than 5 Jciri 2.
There is also provided a method for the cosmetic
treatment of Acne Vulgaris comprising the steps of
providing an illuminating device, and
operating the illuminating device to direct light
radiation on to an area of skin affected by Acne Vulgaris,
wherein
during a single treatment, lasting at least 100ms,
said area receives light energy from the illuminating
device of at least 0.01Jcrri 2,
the light energy so delivered in any given period of
10~,s is less than 0.5 Jcm 2,
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the light energy so delivered in any given period of
100ms is less than 5 Jcrri 2, and
the light energy so delivered causes a photochemical
reaction within the affected skin which at least partially
disables or destroys bacteria contributing to the symptoms
of Acne Vulgaris.
The present invention further provides a method for
improving the appearance of a region of skin by means of
conducting the steps of providing an illuminating device,
and operating the illuminating device to direct light
radiation on to the region of skin, wherein during a period
of at least 100ms, said region receives light energy from
the illuminating device of at least 0.01Jcm'z, the light
energy so delivered in any given period of l0~xs is less
than 0.5Jcm'~, and the light energy so delivered in any
given period of 100ms is less than 5 Jcm'z.
According to another aspect of the invention there is
provided a method for treting the skin condition Acne
Vulgaris, the methods including the steps of providing one
or more light emitting diodes, and operating said one or
more light emitting diodes to direct light radiation on to
a region of skin affected by Acne Vulgaris, wherein during
a single dose lasting at least 100ms, said region receives
light energy from said one or more light emitting diodes of
at least 0.01Jcm-~, and the light energy causes a
photochemical reaction in said region that stimulates the
production of free radicals that react with, and at least
partially disable or destroy, bacteria that contribute to
the symptoms of Acne Vulgaris.
The light energy so delivered advantageously causes a
photochemical reaction within the skin. The method may be
non-therapeutic. In particular, the illuminating device
may be operated in such a way as to cause no therapeutic
effect on the region of skin. Conducting the method may
however result in the cosmetic appearance of the affected
area of skin being improved.
By providing direct light radiation for a longer
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period of time than prior art methods, similar photon or
energy densities can be delivered but at much lower power
densities or energy flux densities, thereby reducing the
likelihood of any adverse reactions of the skin to the
radiation, for example, causing photo-mechanical effects
(explosive expansion of the tissue) or photo-thermal
effects (rapid heating of the tissue). In addition,
providing radiation at lower power means the radiation is
less likely to induce erythema (redness of the skin).
Advantageously, the method of the invention is performed
without any active pre-cooling of the skin immediately
before treatment. Some prior art methods utilising higher
light intensities than in the present invention cause the
target area to be heated so quickly that heat cannot be
effectively dissipated by means of the vascular system,
such methods thus requiring cooling of the skin before
treatment to prevent undesirable effects associated with
the over-heating of the skin.
Preferably, during said period of at least 100ms, said
region receives light energy from the illuminating device
of less than lOkJcm-2, and more preferably less than
lkJcrri2. Preferably, during said period of at least 100ms,
no more than 100Jcrri2 of light energy is delivered over any
given period of 1 minute. The method may be so performed
that during said period of at least 100ms, no more than
100Jcn12 of light energy is delivered over any given period
of 10 minutes. The light energy so delivered in any given
period of 1ms is preferably less than lJcrri2. The light
energy so delivered in any given period of l0ms is
preferably less than lJcm 2. The light energy so delivered
in any given period of 500~.s is preferably less than lJcrri2.
Said period is preferably less than 10 hours.
The light energy so delivered in any given period of
10~,s is preferably less than 50mJcnz2, more preferably is
less than lOmJcm 2, and yet more preferably is less than
SmJcm ~. The light energy so delivered in any given period
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of 10~.s may be less than lmJciri 2.
The lower power requirements of the present invention
compared to prior art methods means that LEDs (Light
Emitting Diodes) can be used rather than lasers. At low
powers, these tend to be cheaper and less complicated than
equivalent laser systems. Also the use of laser devices is
in many countries subject to strict regulations. The
illuminating device thus advantageously includes a
plurality of LEDs, for example, including a plurality of
LEDs grouped together to form an array. A single LED may
be used. For example, the LEDs may form a 1 dimensional
line array or a 2 dimensional array suitable for
illumination of larger areas such as the face or back.
Advantageously, the LEDs could be grouped to form a face
mask under which a user (i.e. a person whose skin is
affected by a skin condition) could be positioned. Using
such a face mask system enables a substantially uniform
dose of radiation to be applied to the whole face within a
short amount of time, for example in a period as short as
30 seconds. In contrast, it can take up to 30 minutes for
an operator to treat a whole face using the single spot
applicator system. In both cases, the skin would receive a
similar dose of light radiation to induce a similar
photochemical response.
The method may be utilised in a method of therapeutic
treatment on the human body. The method may alternatively
be non-therapeutic, in that the method does not treat a
skin disease; rather, the method treats a skin condition.
The method may be in the form of a method of cosmetic
treatment.
The method is preferably for the cosmetic treatment of
Acne Vulgaris. The method may be in the form of a method
for the cosmetic treatment of Rosacea.
The "skin" referred to may be the skin of a mammalian
animal, preferably human. The method is preferably non-
surgical. For example, the illuminating device is
preferably arranged and configured so as to be unable to be
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operated at sufficiently high power to be considered a
surgical device necessitating a skilled operator, such as a
surgeon. Such features provide a key advantage in that the
illuminating device may thus be arranged to be
intrinsically more safe and less complex to operate and
manufacture than the pulsed dye laser of apparatuses of the
prior art.
Performance of the method may cause a photo-chemical
reaction in the skin that disables or destroys, wholly or
partially, the bacteria Propionibacterium acnes, which, as
described above, is one of the causes of Acne Vulgaris.
Propionibacterium acnes is anaerobic and is harmed by the
presence of oxygen. The photo-chemical reaction may be
such that the symptoms of acne are, at least temporarily,
reduced without permanently destroying the agents, for
example the bacteria, that contribute to the symptoms of a
skin condition.
The photo-chemical reaction may take place in a
substance as a result of that substance absorbing radiation
within a range of particular wavelengths (the reaction
being significantly slower or non-existent outside the
range). Preferably the wavelength of radiation used
produces a photo-chemical reaction in a substance (a
chromophore, fox example) of, on or in the skin that
results in the production of free radicals (for example in
the form of oxygen singlets) which thereafter may destroy
the bacterium. The chromophore targeted is preferably
Porphyrin. Porphyrin is a naturally occurring substance
produced by the bacteria Propionibacterium acnes.
Porphyrin produces singlet oxygen when excited by light of
a wavelength of around 5~5nm (yellow light) and also when
excited by light of a wavelength of around 405nm
(violet/near ultra-violet light). Light at other
wavelengths is also able to stimulate free-radical
production.
Thus by exciting Porphyrin in the manner outlined
above it is possible to disable or destroy the bacterium
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responsible for Acne Vulgaris in a pain-free, non-invasive
and efficient manner. The method according to the present
invention provides a means of destroying, at least
partially, the bacteria that contributes to a skin
condition but without needing to use high power lasers,
which as mentioned above have various disadvantages.
The duration of the treatment or the length of the
period during which light radiation is provided by the
illuminating device may, for example, be between 100ms and
30 minutes, is preferably between 200ms and 10 seconds, is
more preferably between 200ms and 3 seconds and is yet more
preferably between 300ms and 2 seconds. The duration or
period may alternatively or additionally be greater than
500ms. The delivery of light radiation may continuous
during a single treatment or during said period.
Alternatively, the delivery of light radiation may be
pulsed during a single treatment or during said period.
The duration of the light radiation is preferably
substantially greater than the thermal relaxation time of
the microvascular system near the area of shin affected by
the skin condition. Thus, the photo-thermal response taught
in GB2368020 is not significant in the proposed method due
to the relatively low dose of light radiation energy
supplied within the hundreds of micro-seconds timescale (of
the same order of time as that of the microvascular thermal
relaxation timescale).
The energy density of the illuminating radiation
delivered may, for example, be between 0.01 and 100 Jcrri2,
is preferably between 0.1 and 10 Jcrri2, is more preferably
between 0.5 and 3 Jcrriz and is even more preferably between
1 and 3 Jcm 2. The energy density may be less than 2 Jcnl2.
Lower energy densities are preferable at longer durations.
The dominant wavelength of the illuminating radiation
is preferably pre-determined. The radiation may, for
example, include radiation having a wavelength of between
350nm and 1500nm, or more preferably between 350nm and
1000nm. The wavelength is preferably between 350nm and
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700nm, more preferably between 570nm and 600nm and is even
more preferably between 580nm and 590nm. The illuminating
radiation may include radiation substantially concentrated
around the wavelength of yellow light (585nm). The
radiation may include radiation having a wavelength of
between 350nm and 450nm, or more preferably between 390nm
and 420nm. The illuminating radiation may include
radiation substantially concentrated around the wavelength
of violet/near ultra-violet light (405nm). Tn accordance
with the invention, especially insofar as the treatment for
Acne Vulgaris is concerned, the radiation may be chosen to
correspond to a photosensitizer such as for example
porphyrin in skin tissue. The wavelength of the light
radiation may be chosen to correspond with a wavelength
suitable for targeting the porphyrin in the skin layers at
a depth suitable to ensure that singlet oxygen is released
which affects the proprionibacterium Acnes without
significantly affecting other tissues.
It is especially advantageous to use radiation at one
or more wavelengths that correspond to one or more of the
peaks of the porphyrin absorption curve.
The illuminating radiation may be provided to an area
of the affected skin of between 12 and 200mm2, for example,
to a spot size of diameter 4-l6mm. The area may be less
than 100mm2. A greater area may be treated however. For
example an area of up to 0.1m~ or even up to 0.5m2 might be
treated simultaneously.
Preferably the illuminating radiation delivered has a
peak optical power level of less than 100Wcni2 and more
preferably less than 10W cm 2. The illuminating radiation
preferably provides a peak optical output power level of
between Z and 5Wcn12.
The light energy so delivered by the illuminating
device may cause a photochemical reaction within the
affected skin thereby stimulating the production of free-
radicals, which react with, and at least partially disable
or destroy, agents causing the skin condition.
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A low power spot or line treatment may be used to "top
up" the higher dose treatment described above. The top up
treatment may for example be provided at lower powers than
the higher dose treatment and over longer periods of time
(for example, overnight). Such a low power treatment might
be particularly well suited to use of the illuminating
device in the home.
The method is preferably performed such that the
distance between the illuminating device and the surface
onto which the radiation is delivered is less than 1000mm,
and is preferably less than 100mm. The distance of
separation may be less than 50mm. The illuminating device
and the surface may be directly adjacent to each other and
may for example touch when radiation is being delivered.
Above, mention is made of light energy causing a
photochemical reaction within the skin. In order to cause
a photochemical reaction in the skin, it is believed that
the extent/amount of the photochemical reaction depends
primarily on the amount of light (i.e. number of photons)
received per unit area and that the power of light used has
a lesser effect. According to certain embodiments of the
invention, it is preferred for the light energy to be
delivered over a relatively long period of time. According
to certain other embodiments of the invention, it is
preferred for the light energy to be delivered over a
relatively short time without exceeding a given power level
that might cause undesirable effects resulting from heating
of the skin. Thus according to some aspects of the
invention it is preferred to have as high a power output as
is reasonably possible without exceeding a maximum power
output, above which there would be a risk of causing such
undesirable effects. It is considered especially
advantageous that the present invention is able to provide
an apparatus that utilises semiconductor light emitting
devices (such as LEDs or laser diodes) that are able to
operate at such power levels.
It will be appreciated that the method of the
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invention may include use of the apparatus of the invention
and that the apparatus of the invention may be arranged and
configured to be suitable for performing the method of the
invention. Thus, features described with reference to the
method of the invention may be incorporated in the
apparatus of the invention. Also, features described with
reference to the apparatus of the invention may be
incorporated in the method of the invention.
An embodiment of the present invention will now be
described by way of example with reference to the following
schematic drawings of which:
Figure 1 shows an apparatus including a control
unit and an illuminating device being used
to treat the skin of a patient;
Figure 2 shows the control unit and illuminating
device of the apparatus shown in Figure 1~
and
Figure 3 shows in greater detail the
illuminating device of the apparatus shown
in Figure 1.
Figure 1 shows an apparatus 10 for the treatment of a
skin condition such as acne by directing light radiation 12
onto the skin 11 of a human patient. The skin to be
treated in this embodiment is an area of skin on the face
including a spot having a diameter about 6mm. The
apparatus 10, in this embodiment a hand-held battery
powered unit, includes an illuminating device 1 and a
control unit 9 linked thereto which controls the radiation
emitted by the device 1. The housing of the apparatus 10
is elongate in shape and has a proximal end via which light
is emitted from the illuminating device 1. The overall
length of the housing is about l5cm.
The apparatus 10, in use, is placed against the skin
with the illuminating device 1 being positioned so as to
direct radiation towards the affected area. Before
operation the apparatus is programmed to set the duration
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of the radiation and the power of radiation. In this
embodiment the apparatus is set to provide a single pulse
of light energy lasting 1 second that delivers 1.5 Jcni~ to
the 6mm diameter spot. The peak power output of the
illuminating device 1 is below 5W/crri2. The energy profile
over time of the radiation delivered is such that the
energy is continuously delivered during the 1 second pulse
and is such that during any period of 10~.s the light energy
delivered is less than 0.5 Jcnl2 and such that during any
period of 100ms the light energy delivered is less than 5
Jcnl2. The method of this embodiment relies solely on
photochemical effects that occur within the skin as is
explained in further detail below. In general, it is
preferable that the method of the invention is so performed
that, and/or the apparatus of the invention is so arranged
that in normal use, there is substantially no beneficial
photo-thermal reaction caused within the skin.
The radiation received by the skin 11 causes a
photochemical reaction in Porphyrin in the skin that
releases singlet oxygen (a free radical), which then
destroys at least some of the bacteria, which is one of the
causes of the symptoms of acne. The radiation received is
however well below the level at which erythema may be
induced. The radiation emitted by the illuminating device
includes light having an intensity that peaks at a
wavelength of about 585nm and includes components of light
radiation having wavelengths in the range of 570-600nm.
Such wavelengths are suitable for targeting the porphyrin
in the skin layers at a depth sufficient for causing the
released reactive oxygen to affect the Propionibacterium
acnes bacteria without significantly affecting other
tissues.
The illuminating device includes a plurality of LEDs 7
arranged in a 2-D array 2 (shown schematically in Figure 2
as LEDs arranged in a close-packed formation) connected to
a lens arrangement (not shown) that focuses the radiation
emitted by the LEDs, so that a concentrated source of light
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is provided. The device 1 is therefore suitable for "spot
treatment" of skin condition (i.e. treating small areas one
at a time). Figure 3 shows other components of the
illuminating device 1, such other components being provided
to cool the LEDs.
Referring to the Fig. 3, there is shown illuminating
device (generally designated 1) comprising, in sequence, an
LED diode array 2, a high thermal conductivity heat
spreader layer 3, a Pettier type thermoelectric cooler 4
and a heat pipe arrangement 5 (including a distal condenser
6) .
The heat spreader 3, thermoelectric cooler 4 and heat
pipe arrangement 5 are provided to keep the operating
temperature of the LEDs at a reduced level and therefore
operating most efficiently. It is well-known that the
efficiency of an LED increases with reduced operating
temperature and in the case of LEDs operating at
wavelengths between 550nm and 650nm this dependence on
temperature is very high.
Heat flowing from the LED diode array 2 is spread over
a larger area by the high conductivity spreader layer 3.
This layer is typically only a few millimetres thick and
provides rapid and highly efficient heat transfer away from
the diode array 2. Heat then flows into the cold end of
the thermoelectric Pettier cooler 4. The hot end of the
thermoelectric Pettier cooler layer 4 is in heat transfer
coupling with the heat pipe 5. The high thermal
conductivity layer 3 includes a diamond material, which is
laid down by means of a plasma/chemical vapour deposition
method.
The Pettier cooler 4 includes a separate control means
including associated drive circuitry which accurately
controls, during use, the heat transfer away from the LED
diode array 2 via the high thermal conductivity spreader
layer 3. Accurate control of the driven Pettier
thermoelectric cooler 4 (in combination with the provision
of the high thermal conductivity heat spreader layer 3 and
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the downstream heat pipe cooling arrangement 5) provides
for extremely efficient thermal management of the
apparatus, and in particular the diode array 2, which
ensures consistency of the light output.
The heat pipe arrangement 5 includes a wick to direct
fluid coolant (contained in the heat pipe arrangement 5)
away from the "hot zone" via capillary action, gravity or
diffusion. The arrangement includes a fluid return system
to return cooled fluid from the "cold zone" at the distal
end of the apparatus, which is provided with a condenser 6.
The condenser 6 is itself cooled by air cooling.
The treatment of Acne using this method has been /
will be trialled on patients suffering from facial acne.
The illuminating device used in these trials was in the
form of a small spot illuminating device (as described
above). During the trials, the radiation emitted during a
single dose was about 1.5J/cnl2 for a 6mm spot size. Trials
are also planned with the use of the illuminating device
similar to that described above but being in the form of a
larger 2-D array of such devices. Such an array of devices
would for example be suitable for illumination and
treatment of larger areas such as the face or back. The
results of the initial trials appear to demonstrate a
beneficial effect on the skin conditions treated.
An alternative apparatus for performing the above
described method is described in WO 03/081127, the subject
matter of which is incorporated herein by reference.
,It will be appreciated that various modifications may
be made to the above-described embodiments of the invention
without departing from the spirit of the invention. Fox
example, the illuminating device used may be in the form of
any illuminating device able to produce controlled doses of
radiation at appropriate energy levels and wavelengths,
without exceeding certain power levels. For example, the
illuminating device may be in the form of a line of a
plurality of the illuminating devices described above (a
"line treatment") or could be in the form of the 2-D array
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_ 22 _
of devices as proposed for use in the trials (a "wide area
treatment"). There may also be provided a lower fluence
device for spot treatment or for line treatment that can be
used to "top-up" the higher dosage spot treatment described
above. Such a low fluence device would be particularly
suitable for home-use.
In the embodiment described above, the wavelength of
radiation used is in the range 570-&OOnm. However, other
embodiments are envisaged that target other peaks in the
porphyrin absorption within the skin tissue. Thus, for
example light radiation having wavelengths in the
violet/near ultra-violet light, blue, green and red
wavelength bands could also be used, either individually,
or in various combinations. The light could be emitted
from a single apparatus (possibly from a single
illuminating device) or by separate apparatuses. The
control unit would of course control the relative levels of
light for the different colours to deliver differing
amounts of reactive light at different depths in the skin -
thereby tailoring the proposed treatment dependent on the
depth of infection by the Propionibacterium acnes bacteria.
