Pulsed dye laser

The pulsed dye laser produces light of a narrowly defined wavelength of about 585 to 595 nanometres – an absorption maximum of oxyhaemoglobin, the oxygen-laden red blood pigment. The laser light is therefore preferentially absorbed in the blood of the dilated capillaries and far less in the surrounding tissue. This principle is called selective photothermolysis: if the energy is delivered in a sufficiently short pulse – matched to the thermal relaxation time of the target vessel – it heats the vessel so strongly that it coagulates and closes, before any appreciable heat is transferred to the surroundings.

At higher energies, the targeted bursting of the tiniest vessels may occur – visible as pinpoint, blue-red bruising (purpura), a known, often desired indication that the vessels have been sufficiently reached; the body breaks down the closed vessels over days to weeks. Modern devices cool the skin surface immediately before the light pulse, protecting the epidermis. The treating physician individually adjusts energy (fluence), pulse duration, spot size and cooling to the findings – these settings are decisive for efficacy and safety.

It is important to understand that the dye laser tackles the visible vessels, but does not eliminate the underlying predisposition. In rosacea or a constitutional couperose, the treatment can reduce the visible redness, but the tendency towards vascular dilation persists – accompanying measures such as consistent sun protection and avoiding individual triggers therefore play an important role.

The pulsed dye laser is among the longest- and best-studied laser systems for superficial vascular skin changes. Controlled studies and systematic reviews show that port-wine stains (naevi flammei), vascular redness and dilated capillaries can in many cases be visibly lightened; for port-wine stains the procedure is professionally regarded as an established standard, whereby the success depends on location, colour, depth and prior treatment, and not every change disappears completely. For rosacea and couperose, too, a reduction of redness and visible capillaries is documented – the realistic expectation is an improvement in the appearance of the skin, not a cure of the underlying condition. For reddened or overshooting scars, the data are more heterogeneous.

When classifying the evidence, honesty is important: the studies differ in devices, settings, skin types and assessment methods, in part with small numbers of cases and short follow-up. Results vary from person to person and cannot be guaranteed. Orientation is offered by the guidelines listed in the AWMF register as well as recommendations of dermatological specialist societies such as the German Dermatological Society (DDG), on the basis of which we assess your findings.