The wavelengths produced by the A.P.T.D.L. include a yellow-band at 585 nanometers 1 which is selectively absorbed by oxyhemoglobin, the principal chromophore in oxygenated blood. This feature permits targeted treatment for vascular lesions like telangiectases or port-wine stains. The argon pumped tunable dye laser can also produce blue-green bands at 480 to 532 nanometers. Selective absorption of these wavelengths by melanin permits the directed treatment of benign melanotic lesions like lentigines. Thus, the principal clinical application of the A.P.T. dye laser is to treat cutaneous vascular disorders and pigmented lesions with minimal or no danger to the epidermis.
Organic compounds dissolved in solvents are the active molecules in all dye lasers.
These dyes absorb strongly in various portions of the visible spectrum to produce colored light. Other indications are shown in Table 1. The A.P.T.D.L. is not very effective for telangiectasias of the extremities, thick boggy hemangiomas or hemangiomas in children. Overlying skin and melanocytes are relatively impervious to laser light at this wavelength. Therefore, selective injury to the blood vessels, but not adjacent tissue, occurs.