Dye laser

A dye laser uses an organic dye mixed in a solvent as the lasing medium. Some of the laser dyes include rhodamine, fluorescein, coumarin, stilbene, umbelliferone, tetracene and malachite green. Some of the solvents used include water, glycol, ethanol, methanol, hexane, cyclohexane and cyclodextrin. A high energy source of light such as a fast discharge flashlamp or an external laser (eg, ND:YAG laser) is needed to “pump” the liquid beyond its lasing threshold. The dye solution is usually circulated at high speeds, to help avoid triplet absorption and to decrease degradation of the dye. The incoming light excites the dye molecules into the state of being ready to emit stimulated radiation. Pulsed dye lasers produce pulses of visible light at a wavelength of 585 or 650nm. The selected wavelength of laser light is absorbed to a high degree by the target structure (called chromophores) compared to surrounding tissue. The pulse duration of laser energy is shorter than the target structure’s thermal relaxation time, which is the time taken for the target to cool by 50% of its peak temperature after irradiation. This ensures that the impact of thermal energy is limited to the target structure and does not affect the surrounding tissue.

Application

Cutaneous vascular lesions: treatment of port wine stains (vascular malformation), superficial haemangiomas and a variety of acquired cutaneous vascular lesions, including telangiectasis, cherry angiomas and poikiloderma of Civatte.
Non-vascular skin conditions: widely used to treat several nonvascular conditions including plane warts, angiofibroma (tuberous sclerosis) and pyogenic granulomas.
Burn and hypertrophic scars
Melasma
Nail psoriasis/plaque psoriasis