SELECTIVE SKIN TREATMENTS UTILIZING LASER-EQUIVALENT INTENSE PULSED LIGHT DEVICES

Abstract

A cosmetic method of providing light treatment to skin tissue includes: providing an intense pulsed light (IPL) source; interposing a band pass filter between the IPL source and the skin tissue; the band pass filter passes light in a selected range of wavelengths with an average absorption coefficient equivalent to that of a selected laser light source; the method includes activating the IPL source and applying it to the skin tissue, wherein the filtered light impinging on the skin tissue provides equivalent treatment to that of the selected laser light source.

Claims

1. A device for the cosmetic treatment of vascular lesions on skin tissue, wherein the device is an equivalent of a laser having an operating wavelength of one of: 532 nm, 595 nm or 755 nm, the device comprising: an intense pulsed light (IPL) source, the IPL source being activatable; further comprising a band pass filter which blocks substantially all but one range of wavelengths of light emanating from the IPL source when activated; wherein the band pass filter permits transmission of light from the IPL source when activated in the range of one of: about 525 nm to about 585 nm about 560 nm to about 690 nm, or about 700 nm to about 800 nm; and, wherein the IPL with the band pass filter provides equivalent cosmetic treatment as a laser with an operating wavelength of 532 nm, 595 nm or 755 nm respectively.

2. A method of providing cosmetic treatment equivalent to one of: a 532 nm laser, a 595 nm laser or a 755 nm laser on a body vascular region comprising: providing an intense pulsed light (IPL) source; interposing a band pass filter between the IPL source and the body vascular region; wherein the band pass filter is of a type that substantially passes light in the range of one of: about 525 nm to about 585 nm, about 525 nm to about 585 nm about 560 nm to about 690 nm, or about 700 nm to about 800 nm; activating the IPL source; wherein the filtered light impinging on the vascular body portion provides cosmetic treatment equivalent to that of the 532 nm laser, 595 nm or 755 nm respectively.

3. A cosmetic method of providing light treatment to skin tissue, the method comprising: providing an intense pulsed light (IPL) source; interposing a band pass filter between the IPL source and the skin tissue; wherein the band pass filter passes light in a selected range of wavelengths with one of: an average absorption coefficient equivalent to that of a selected laser light source or the average depth of penetration of the selected band pass filter in the skin tissue; activating the IPL source and applying it to the skin tissue, wherein the filtered light impinging on the skin tissue provides equivalent treatment to that of the selected laser light source.

4. The device of claim 3, wherein the IPL source further comprises a body portion which includes the IPL source and an opening in the body portion to accept one or more band pass filters and wherein the one or more band pass filters are filters which pass different ranges of light from the IPL source to the skin tissue.

5. A method of selecting an IPL light source having a band pass filter equivalent to a specified wavelength laser light source for providing cosmetic treatment of skin tissue, the steps comprising: selecting a laser light source of a specified wavelength; activating the laser light source; directing the laser light source at a target; measuring one of: the average absorption coefficient of the selected laser in the target or the average depth of penetration of the selected laser in the target; storing one of: the measured coefficient or the measured depth of penetration; selecting a band pass filter; activating the IPL light source; measuring one of: the average absorption coefficient of the selected band pass filter in the target or the average depth of penetration of the selected band pass filter in the target; comparing the measured coefficient or the depth of penetration of the band pass filter with the stored measured coefficient or the stored measured depth of penetration of the selected laser light source; and, if the measured coefficients or the measured average depths of penetration substantially match, determining that the selected laser light source and the IPL light source with the selected band pass filter are equivalent.

6. The method of claim 1, wherein the target is skin tissue.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIG. 1 graphically illustrates absorption of blood by light of various wavelengths.

[0025] FIG. 2 illustrates by a table the absorbent coefficients shown in FIG. 1

[0026] FIG. 3 graphically illustrates absorption of melanin by light in various wavelengths.

[0027] FIG. 4 illustrates in a table the absorbent coefficients shown in FIG. 3.

[0028] FIG. 5 illustrates graphically the ratio of the absorption coefficient of light in melanin over blood as a function of wavelength.

[0029] FIG. 6 illustrates graphically penetration depths of light into tissue at various wavelengths.

[0030] FIG. 7 illustrates graphically at different wavelengths the relative efficiency of IPL light sources.

[0031] FIGS. 8 and 9 illustrate in tabular form typical numerical values of optical absorption at different wavelengths for different chromophores.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0032] The absorption coefficient of light in tissue or chromophore is a function of wavelength. Referring now to FIG. 1, shown is a graph of light absorption values in whole blood as a function of wavelength for a 532 laser filter in solid lines and a Dye laser filter in dashed lines. In this non-limiting example, the blood is assumed to consist of about 70% oxyhemoglobin and 30% deoxyhemoglobin on the average. It can be seen that the absorption level varies with the wavelength.

[0033] FIG. 2 shows a table containing selected numerical values derived from the graph of FIG. 1. Alternatively, FIG. 3 shows a graph of the absorption values of light in melanin as a function of wavelength while FIG. 4 provides selected numerical values derived from the graph of FIG. 3. FIGS. 8 and 9 list typical numerical values of optical absorption at different wavelengths for different chromophores. Average absorption calculations which will be given as examples below are based on these numerical values.

[0034] As can be seen, for example, from FIG. 2, the absorption coefficient of blood at a wavelength of 532 nm is about 232 l/cm. Therefore, according to this aspect of the invention, a band pass filter for an IPL system may be provided in the range of 525 to 585 nm, as indicated in FIG. 1 as 532 laser filter for vascular lesion treatment and as indicated in FIG. 9 which shows an example of a range of wavelengths which can be chosen to provide an equivalent averaged absorption coefficient as provided by the laser. The average absorption coefficient referring to all wavelengths in this range in blood, is equal to the 232 l/cm which characterizes the 532 KTP laser absorbance in blood. Therefore, an IPL system having such a band pass filter would be expected to have a similar tissue interaction on skin as would the 532 nm laser and may be as effective in the treatment of vascular lesions as a 532 nm laser.

[0035] As another example illustrated in FIG. 2, a dye laser which has a wavelength of about 595 nm has an absorption coefficient in the blood of about 60 l/cm. The average absorption coefficient value of the band pass filter between 560 nm and 690 nm will have the same average absorption coefficient in blood as a dye laser and therefore, according to this aspect of the invention, an IPL system with a band pass filter of 560 nm to 690 nm, dye laser filter as may be seen marked in FIG. 2 as such, may be provided for the treatment of vascular lesions.

[0036] As another example, and referring now to FIG. 3, an alexandrine laser (755 nm) has an absorption coefficient of about 172 l/cm in melanin, as may be seen in FIG. 3. A band pass filter from, for example, 700 nm to 800 nm passes a light spectrum which has, on the average, an absorption coefficient in melanin of 173 l/cm and therefore, according to this aspect of the present invention, an IPL system having a band pass filter between 700 nm to 800 nm is provided as an equivalent to an Alexandrite laser and called herein an Alexandrite laser filter. A band pass filter which passes a light spectrum from 675 nm to 900 nm may provide similar results.

[0037] FIG. 8 is a table with examples of ranges of wavelengths which can be chosen to provide, in an IPL device, an equivalent averaged absorption coefficient as the laser Alexandrite. Such an IPL system may be deemed to be characterized with the same or very similar clinical effects as an Alexandrite laser for the treatment of pigmented lesions.

[0038] According to another aspect of the present invention, an IPL system may be provided having an IPL handpiece which has a permanent embedded filter which is configured to hold a band pass filter which delivers a spectrum of light which has an average absorption coefficient which is about similar to the absorption coefficient of one of the known laser wavelengths, such as for example KTP, 532 nm, pulsed dye laser (PDL) 585 nm-595 nm, Alexandrite 755 nm, diode laser 800-810 nm and Nd:YAG 532, Ruby 694 nm or 1,064 nm and more.

[0039] According to yet another aspect of the present invention, an IPL system with an IPL handpiece may be configured to accept different filters, each in accordance with the present invention, so that a single handpiece may interchangeably deliver light spectrums which have average absorption coefficients on a target tissue or chromophore similar to those of equivalent known lasers. A device manufactured and sold by the assignee of the present invention, Lumenis LTD of Israel, named the M22 Universal IPL, is an example of such a device that accepts different filters.

[0040] The average calculation of a series of absorption values associated with a certain light spectrum which is passed through a band pass filter as described above, can be made in different ways. In the above examples, the calculation of the average was a basic arithmetic average calculation in which the weight of each wavelength is similar. However, as can be seen in FIG. 6, the penetration depth of light into a tissue, such as skin, varies and is also a function of wavelength. Therefore, according to another aspect of the invention, the average absorption coefficient of a spectrum of light passed through a band pass filter in accordance with the present invention may be calculated based on a weighted average calculation.

[0041] Moreover, due to the dependency of the depth of penetration on the wavelength, spots in different depths in the skin will experience different effective wavelength intensity distribution. In general, there is a shift towards red and mid-infrared of the spectrum as depth increases. Therefore, according to this aspect of the present invention, an IPL system is provided having an IPL band pass filter which is configured to deliver a spectrum of light which has an average absorption coefficient of a target tissue or chromophore which is similar to the absorption coefficient of a known laser at a predefined depth in the skin.

[0042] For example, on the skin surface, an Alexandrite laser of 755 nm has an absorption value of an about 172 l/cm in melanin, as can be seen in FIG. 4. As can be seen in FIG. 3, a spectrum of light which on the average will have a similar absorption in melanin as the Alexandrite laser may be a band pass filter of 700 nm to 800 nm. It should be mentioned that different band pass filters may also, on the average, produce a spectrum with an averaged absorption coefficient similar to an Alexandrite laser, for example, a band pass filter of 725 nm to 775 nm.

[0043] As mentioned above, a critical energy threshold also preferably is reached in order to achieve a required clinical effect. Therefore, a band pass filter should be chosen, based on the lamp performances and intensity, to not only deliver a spectrum having an average light absorption in a target tissue or chromophore similar to that of a known laser but also to deliver at least the threshold energy to achieve a clinical effect. Turning attention now back to the example concerning the depth of a target tissue in the skin, an Alexandrite laser filter for pigmented lesion, which aims to target melanin deeper in the skin due to the shift toward mid-infrared, may need to deliver a slightly different light spectrum shifted toward blue, in order to keep the average absorption value of the delivered spectrum around the 172 l/cm+ at this deeper location.

[0044] According to another aspect of the present invention, as can be seen in FIG. 7, the energy emitted from a lamp is also a function of wavelength. At different wavelengths, the efficiency of the lamp is different and therefore a different amount of energy is irradiated and delivered Therefore, as mentioned above, a weighted average calculation may be performed in order to compensate for uneven energy distribution of the lamp. An IPL system and an appropriate band pass filter which is configured to deliver a light spectrum which on a weighted average basis has an absorption coefficient value in the skin or anywhere inside the skin which is similar to the absorption coefficient value of a known laser in a target tissue or chromophore is also an aspect of the present invention.

[0045] FIG. 5 shows the ratio of the absorption coefficient of light in melanin over blood as a function of the wavelength. As can be seen, in a wavelength range of 600 nm to 900 nm, the ratio is higher than 10. Therefore, according to this aspect of the present invention, the band pass filter of the present invention may be configured to pass a spectrum of wavelengths in which the ratio of the absorption of light in melanin over the absorption of light in blood is at least above 10 l/cm. A ratio higher than 10 l/cm will be expected to produce good selectivity for the treatment of pigmented lesion. According to another embodiment, an IPL system may be configured to deliver a light spectrum having a ratio larger than 20 l/cm, larger than 30 l/cm, larger than 40 l/cm or larger than 50 l/cm to further enhance selectivity. According to this aspect of the invention, and to other aspects of the present invention, a lamp having a high degree of brightness is configured to deliver high energy fluences and therefore, even with the use of a relatively narrow band pass filters, a threshold energy sufficient to produce a clinical effect will be achieved.

[0046] One example of a suitable flash lamp for practicing the present invention may be that flashlamp structure as described in U.S. Provisional Application Ser. No. 62/465,210, filed Mar. 1, 2017.