Vascular Assessment · Wavelength Selection · CityLink Mall
Visible red lines across the nose and cheeks are permanently dilated blood vessels sitting in the dermis. They are a vascular target, not a pigment one — which is why the lasers that clear brown marks do nothing to them, and why choosing the wavelength is the whole treatment decision.
Small dermal blood vessels are supposed to dilate and constrict continuously — that is how skin regulates temperature and responds to stimuli. A telangiectasia is a vessel that has lost that ability. It has become permanently dilated, wide enough that the column of blood inside it is visible through the overlying skin, and it no longer returns to its resting calibre when the stimulus passes. The colour depends on depth and vessel type: superficial capillaries read bright red, deeper venules read blue or violaceous.
Two things allow that to happen. The first is loss of the dermal scaffold around the vessel. Collagen and elastin form a supporting matrix that physically restrains vessel diameter, and chronic ultraviolet exposure degrades it — which is why telangiectasia appear on the nose, cheeks and ears rather than on skin that never sees the sun. The second is repeated or sustained vasodilation, which is where rosacea enters the picture: years of flushing on a photodamaged dermis produce fixed vessels from vessels that were initially only transiently dilated.
Other causes produce the same endpoint by different routes. Prolonged application of topical corticosteroid to facial skin thins the dermis and is a well-recognised cause, frequently in patients who were using it for something else entirely. Trauma, previous surgery and certain genetic conditions can all produce localised telangiectasia. Hormonal states and liver disease account for spider naevi, which have a characteristic central feeding arteriole with radiating branches and blanch centrally on pressure.
Whatever the route, the end state is the same and it does not resolve. A dilated vessel that has lost vasomotor tone stays dilated, and no topical agent reaches it or acts on it. Vitamin C, niacinamide and barrier repair may reduce the background erythema and the tendency to flush, which is genuinely useful, but they do not close a fixed vessel. Closing a fixed vessel requires depositing enough heat inside it to coagulate its wall, and that is a question of physics.
Types
Facial vessels are not one target. Calibre, depth and whether there is a feeding vessel all change which wavelength and which pulse duration will work, and they change what a realistic number of sessions looks like. Separating them at examination is what prevents the common outcome of a treatment that clears some vessels and leaves others untouched.
A pigment laser cannot close a blood vessel. It is tuned to melanin and its pulse ends before the vessel has had time to heat — the target and the timing are both wrong.
The Decision
Selective photothermolysis is the principle underlying all of this, and it has two requirements. The target has to absorb the wavelength being delivered more strongly than the surrounding tissue does, and the pulse has to last long enough to heat the target to a damaging temperature but not so long that heat spreads into the tissue around it. Haemoglobin absorbs strongly in the region of 418, 542 and 577 nanometres, which is why 532 nm KTP and 595 nm pulsed dye lasers are the vascular workhorses, and why longer 1064 nm wavelengths are chosen where vessels sit deeper and require more penetration.
Pulse duration is the half of the equation people forget, and it is where pigment devices fail this indication. A vessel of typical telangiectatic calibre has a thermal relaxation time in the millisecond range — it needs to be heated over milliseconds to coagulate the whole vessel wall. Pigment lasers deliver nanosecond or picosecond pulses deliberately, because shattering a melanin particle requires an extremely short, extremely intense burst. That pulse is over long before a blood vessel has meaningfully warmed. Toning protocols are built around the same physics and the same target, and neither is a vascular treatment however often they are offered as one.
The other half of the decision is what is underneath. Telangiectasia sitting on a rosacea background will be joined by new vessels if the rosacea is not controlled, and treating the vessels alone produces a patient who returns annually, puzzled. Telangiectasia caused by ongoing topical steroid will recur while the steroid continues. In Asian skin there is a further consideration: vascular wavelengths are also absorbed to some degree by epidermal melanin, so settings are calibrated conservatively to avoid post-inflammatory pigment change, which is a more common complication here than anywhere else.
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