Method and apparatus for treating dermal melasma

Abstract

Exemplary methods and devices can be provided for improving the appearance of dermal melasma. This can be done, e.g., focusing electromagnetic radiation having a wavelength between about 600 nm and 850 nm into a region of the pigmented dermal tissue at a depth between about 150 and 400 microns, using a lens arrangement having a large numerical aperture between about 0.5 and 0.9. The exemplary local dwell time of the focused radiation can be less than a few milliseconds, and a local fluence provided in the focal region can be between about 50 and 500 J/cm 2 . The focal region can be scanned through the dermal tissue at speeds on the order of a few cm/s. Such parameters can provide sufficient energy absorption by pigmented cells in the dermis to disrupt them while avoiding damage to the overlying tissue and unpigmented dermal tissue.

1 - 32 . (canceled) 
     
     
         33 . An apparatus for selectively affecting a pigmented region in a layer of a skin tissue, comprising:
 a radiation arrangement including at least one laser configured to emit at least one electromagnetic radiation (EMR) beam;   an optical arrangement including at least one lens configured to direct and focus the at least one EMR beam as a convergent beam into at least one focal region having a width less than 100 μm within a dermis layer of the skin tissue containing pigmented and unpigmented regions;   a sensor configured to detect a speed of a translation of the apparatus over the surface of the skin tissue, and provide signals which are based on the detected speed to affect at least one property of the at least one EMR beam; and   a controller configured to receive the signals from the first sensor and to control:
 a power output of the radiation arrangement so as to provide a fluence of the at least one EMR beam between 10 and 1000 J/cm 2  in the at least one focal region when the signals indicate that the apparatus is in motion over the surface of the skin tissue, and 
 at least one of the radiation arrangement or the optical arrangement so as to scan the at least one EMR beam over an entirety of a treatment area of the skin tissue within the dermis layer, 
   wherein a dwell time of the at least one EMR beam at the at least one focal region is 2 ms or less, and   wherein, in operation, the at least one EMR beam (i) provides selective energy absorption by the pigmented regions of the skin tissue within the treatment area, and (ii) damages the pigmented regions while preventing damage to the unpigmented regions of the skin tissue within the treatment area and within an epidermal layer of the skin tissue overlying the at least one focal region.   
     
     
         34 . The apparatus of  claim 33 , wherein a wavelength of the at least one EMR beam is between 500 and 850 nm. 
     
     
         35 . The apparatus of  claim 33 , wherein the controller is configured to turn off the radiation arrangement when the apparatus is stationary relative to the surface of the skin tissue. 
     
     
         36 . The apparatus of  claim 33 , wherein a scan speed of the at least one EMR beam is between 5 mm/s to 5 cm/s. 
     
     
         37 . The apparatus of  claim 33 , wherein the optical arrangement comprises a plurality of lenses. 
     
     
         38 . The apparatus of  claim 37 , wherein a width of each one of the plurality of lenses is between 1 mm and 3 mm. 
     
     
         39 . The apparatus of  claim 38 , wherein at least two of the plurality of lenses have different focal lengths. 
     
     
         40 . The apparatus of  claim 33 , wherein the optical arrangement comprises a plate having a lower surface configured contact the surface of the skin tissue. 
     
     
         41 . The apparatus of  claim 33 , further comprising an additional sensor configured to (i) detect contact of the apparatus with the skin surface, and (ii) provide additional signals to affect at least one property of the at least one EMR beam based on the detected contact. 
     
     
         42 . The apparatus of  claim 41 , wherein the controller is configured to(i) receive the additional signals, and (ii) turn on the radiation arrangement when the apparatus contacts the skin surface. 
     
     
         43 . The apparatus of  claim 33 , wherein the optical arrangement has a numerical aperture that is between 0.5 and 0.9.