Photodynamic therapy.

Photodynamic therapy (PDT) involves the use of a class of molecules that are activated by light, and which accumulate in, and are retained by, certain abnormal tissues. When these molecules (known as photosensitizers) are activated by light, they cause the formation of active forms of oxygen, which result in the killing of cells in which the photosensitizers are present. Thus, PDT can be used to destroy diseased areas of tissue selectively, while sparing the normal surrounding tissue. PDT has been extensively studied in the treatment of cancer, but the technology has potential as a treatment in a number of other disease conditions.