Treatment of pigmented tissues using optical energy

Abstract

A method and apparatus for selectively photobleaching or killing pigmented tissues by photochemically converting pigments in the tissues using light and specifically two-photon excitation. Phototoxic products thereby produced then kill pigmented cells. Hyperthermia or an exogenous agent can also be added to augment efficacy. The present invention is also directed to selective thermal destruction of pigmented tissues using related optical means.

1 . A method for the treatment of a particular volume of tissue, said volume of tissue containing an endogenous pigment, the method comprising the steps of: 
 non-invasively treating the particular volume of tissue by scanning with a beam of light to promote thermal overload of pigmented cells in the particular volume of tissue, wherein said thermal overload kills said pigmented cells, wherein said light is produced by a single light source, and wherein said light is applied to said volume of tissue continuously for a duration of at least 10 microseconds.    
   
   
       2 . The method of  claim 1  wherein the light to promote said thermal overload is a laser light produced by a laser.  
   
   
       3 . The method of  claim 2  wherein the laser light comprises a train of one or more pulses.  
   
   
       4 . The method of  claim 2  including operating the laser to produce light at a wavelength between approximately 450 nm to 800 nm.  
   
   
       5 . The method of  claim 4  wherein said wavelength of light is between approximately 600 nm and 800 nm.  
   
   
       6 . The method of  claim 4  wherein said particular volume of tissue is located substantially at the tissue surface.  
   
   
       7 . The method of  claim 4  wherein said particular volume of tissue is located approximately 2 mm or less below the tissue surface.  
   
   
       8 . The method of  claim 2  including operating the laser to produce light at a wavelength between approximately 800 nm to 1400 nm.  
   
   
       9 . The method of  claim 8  wherein said particular volume of tissue is located approximately 2 mm or greater below the tissue surface.  
   
   
       10 . The method of  claim 1  wherein the light to promote said thermal overload is a focused beam of light.  
   
   
       11 . The method of  claim 10  wherein the focused beam of light is focused laser light.  
   
   
       12 . The method of  claim 1  wherein the light to promote said thermal overload is a non-focused beam of light.  
   
   
       13 . The method of  claim 1  wherein said endogenous pigment is selected from the group comprising melanin, melanin precursors, carotenes, porphyrins, and various tattoo dyes.  
   
   
       14 . The method of  claim 13  wherein said melanin precursors are selected from the group comprising 5-S-cysteinyldopa (5-SCD) and 5,6-dihidroxyindole (DHI), dopa, dopa semiquinone, leucodopachrome, dopachrome, eumalanins, pheomelanins, sepia melanins, and 5,6-dihydroxyindole-2-carboxylic acid.  
   
   
       15 . The method of  claim 13  wherein said porphyrins include hemoglobin.