Photodynamic Therapy

The LED red light (630 nm) has been used for several years in combination with a sen­sitizer (levulinic acid) for photodynamic therapy (PDT) [28]. When exposed to light with the proper wavelength, the sensitizer produces an activated oxygen species, singlet oxygen, that oxidizes the plasma membrane of targeted cells. Due to a lower metabolic rate, there is less sensitizer in the adjacent normal tissue, thus less of reaction. One of the absorption peaks of the metabolic product of levulinic acid, protoporphyrin, absorbs strongly at 630 nm red. A red LED panel emitting at 630 nm (Omnilux PDT™, Phototherapeutics, Lake For­est, CA) has been used for this purpose in Europe and Asia [29]. We have also used the full panel 590 nm LED array for facilitating PDT. This therapy is delivered by the application of levulinic acid (Levulan™ DUSA, Wilmington, MA) for 45 min and exposure to continu­ous (nonpulsed) 590 nm/870 nm LED for 15 min for a cumulative dose of over 70 J/cm2. Our results have shown reduction of actinic damage, including improvement of skin texture and reduction of actinic keratoses [30].