No, and they are not alternatives to each other. The CO2 laser removes and rebuilds tissue to change the shape and texture of a scar. The KTP laser is absorbed by blood and changes the colour. A scar that is both red and depressed often needs both, in sequence rather than on the same day.
Overview
Redness is the part of a scar that can be reached early
A new scar is red because of the vessels inside it. That is the one component of a scar that responds to light, and it responds best while the scar is still young.
The Derma V is a solid-state laser workstation from Cynosure Lutronic that carries two wavelengths: 532 nm, the green KTP-type wavelength this page is about, and 1064 nm for deeper and darker targets. It has contact cooling and variable sequential pulsing, which allows the pulse to be broken up and matched to vessels of different calibre rather than delivered as one fixed burst.
What makes 532 nm useful on a fresh scar is where it sits on the absorption curve. Oxyhaemoglobin takes up green light far more strongly than it takes up the 595 nm of a pulsed dye laser, so a smaller amount of energy is needed to heat and close the vessel. The trade-off is depth: green light does not travel far into the dermis, which makes it an instrument for superficial redness rather than for deep vasculature.
It is worth being clear about what this does not do. A laser aimed at haemoglobin does not lift a depressed scar, release a tether or rebuild a torn dermis. It takes the colour out. On a scar that is red and depressed, colour and contour are two separate problems with two separate answers, and we would rather sequence them properly than treat one and let you assume we have treated both.
At a glance
- Treatment timeMinutes for a single scar; longer for a field of striae
- AnaestheticNone usually required; contact cooling during the pass
- DowntimeRedness for a few hours; occasional transient purpura
- SessionsPublished protocols use 3, about 6 weeks apart
- ResultsColour settles over weeks; assessed about 12 weeks after the last session
- Combines withFractional CO2 laser, subcision, RF microneedling
How it works
Green light, haemoglobin, and a window that closes
The principle is selective photothermolysis. A wavelength is chosen that the target absorbs much more strongly than the surrounding skin does, and a pulse duration is chosen that is short enough to keep the heat inside the target. At 532 nm the target is the oxyhaemoglobin in the small vessels of the papillary dermis. The blood heats, the vessel wall coagulates, and the body clears what is left.
In an immature scar those vessels are not incidental. New scar tissue is richly vascularised, and that neovascularisation is both what makes the scar red and part of what keeps it metabolically active. Closing it changes the colour directly, and the controlled injury itself provokes a modest remodelling response in the surrounding collagen.
Two limits follow from the physics rather than from the device. First, depth: green light is absorbed so efficiently near the surface that little of it reaches deep vessels, which is where the 1064 nm wavelength on the same platform takes over. Second, melanin also absorbs green light. In darker or tanned skin the pigment competes with the blood for the same energy, which raises the risk of a pigmentary reaction and is why this wavelength is used conservatively, at lower fluence and with a test patch, outside Fitzpatrick I–III.
And there is a window. A scar that has turned pale has no vascular target left. The published work on vascular lasers for scars treats them while they are still red, and a patient who waits two years for a scar to “settle down” before asking about treatment has usually waited past the point where this particular instrument has anything to offer.
Indications
Suited to
- Fresh surgical and traumatic scars, while still in the red, immature phase
- Post-inflammatory erythema after acne, or after a resurfacing treatment
- Red stretch marks (striae rubrae), for the colour component
- Hypertrophic scars where redness and thickness have arrived together
- Telangiectasia and background facial redness in the same field
- The scar or stretch mark has already turned white — there is no longer a target for this wavelength
- Fitzpatrick IV and above, or recently tanned skin, without a test patch and a conversation about pigment first
- Contour is the main complaint — the colour can improve while the depression stays exactly as it was
- Skin that cannot be kept out of the sun before and after a course
- Active infection or a cold sore in the field
- An expectation that the scar will disappear rather than fade
In the clinic
Step by step
Assessment and photography
The scar is assessed for how much of its appearance is colour and how much is contour, and photographed against a standardised background so that the comparison later is a real one.
Test patch
In anything but pale, untanned skin a small test area is treated first and reviewed before a full session is booked. Green light and melanin compete, and this is how that is managed rather than guessed.
The pass
Protective eyewear on, cooling applied, and the handpiece passed over the scar. You feel a brief snap with each pulse. A single linear scar takes minutes.
Immediately after
The area looks pink and may swell slightly. Where settings were higher there may be fine purpuric spots. Cool compresses and sunscreen before you leave.
Between sessions
Roughly six weeks, which is the interval used in the published work and long enough for the colour to declare where it has actually settled.
The review
About twelve weeks after the final session, on photographs taken in the same light and position as the first set. That is when the result is judged, not at the end of the last treatment.
Recovery
What the days after look like
This is the gentlest of the scar treatments on this site. Most patients go back to work the same day, and the main thing we ask of you afterwards is to stay out of the sun.
The treated area is pink and slightly swollen for a few hours, sometimes into the next day. Where higher settings have been used, small bruise-like purpuric spots can appear and take a few days to clear; that is a recognised effect of a vascular laser rather than a complication, but it is worth knowing before a social engagement. Make-up can be applied as soon as the skin is intact and comfortable.
Sun protection is the whole of the aftercare. Green light and melanin compete for the same energy, so treated skin that is then exposed to sun is the main route to a pigmentary reaction. Daily SPF 30+ and genuine shade for a fortnight either side of each session is not a suggestion, it is the condition on which the safety of the treatment rests.
Risks
What can go wrong
Expected
A brief stinging during the pass, then redness and mild swelling of the treated area for a few hours to a day.
Uncommon
Transient purpura — small bruise-like marks where a vessel has been closed at higher energy — clearing over several days. Mild crusting. Post-inflammatory hyperpigmentation, which is the risk that governs this wavelength and relates to phototype, recent sun exposure and settings rather than to the scar itself.
Rare but serious
Blistering, and the hypopigmentation or textural scarring that can follow it if the surface is damaged. These are the reason a test patch is used in anything but the palest untanned skin, and the reason settings are raised gradually across a course rather than at the first session.
In the randomised comparison against the pulsed dye laser, side effects on the KTP side were limited to mild discomfort during treatment and transient redness and purpura afterwards; no blistering, infection or scarring occurred. That was twenty patients, which is a reassuring signal rather than a safety guarantee.
Evidence
What the evidence shows
Good for colour, modest overall, thin for stretch marksThe one head-to-head study is small but directly on the point. Twenty patients with matched or split erythematous surgical scars were randomised to three sessions, six weeks apart, of either a 532 nm KTP laser or a 595 nm pulsed dye laser at equivalent settings, and assessed twelve weeks after the last treatment by blinded photographic review. Both improved. Neither was significantly better than the other on the blinded assessment, on investigator or patient satisfaction, on symptoms or on pain — the KTP arm came out ahead on one measure only, the vascularity component of the Vancouver Scar Scale. Read plainly: the green laser is a legitimate alternative to the long-established pulsed dye laser for red scars, not an upgrade on it.
The largest trial of early laser on scars points the same way about size of effect. The ELABS trial randomised 153 patients across seven UK centres to three pulsed dye laser treatments plus standard care, or standard care alone, for hypertrophic burn scars. At six months, patients rated their own scars as better (p = 0.041) and said they had noticed a change (p = 0.01) — but there was no significant difference in quality of life, in the observer-rated score, or in objective colour measurement, and the treatment was not cost-effective at that point. It was safe. The authors are explicit that two years of follow-up would be needed before drawing conclusions.
For stretch marks the evidence is weaker still, and we would rather say so here than in the consultation room. The 2025 systematic review of treatments for striae is blunt that the literature is limited, the samples small and the results highly variable. Red striae do respond better than white ones, and a laser aimed at haemoglobin is the logical choice for the red phase. But the three interventions that come out of that review with the best evidence are fractional CO2 laser, topical tretinoin and microneedling radiofrequency — none of them vascular lasers. In the pulsed dye laser work, red striae improved modestly and white striae not at all, and in the light-based studies the gains drifted back towards the untreated group over six months of follow-up. Treating the colour of a stretch mark is a reasonable thing to do. Treating the stretch mark is a longer project.
One regulatory note, because it is the honest thing to put in writing: the 532 nm wavelength on this platform is indicated by its manufacturer for vascular, pigmented and cutaneous lesions. Stretch marks are not among the named indications, and treating them is a reasoned off-label use of the device rather than a cleared one.
If you are travelling
Of all the treatments on this site, this is the easiest one to fit around a journey. There is no wound, no dressing and no reason not to fly the same day.
What needs planning is the course rather than the session. Published protocols run three treatments at roughly six-week intervals, so a full course spans about four months — which for an international patient usually means combining it with something else on each visit rather than travelling for this alone.
If purpura would be awkward, say so before we choose settings. There are gentler parameters that trade a little efficacy for no visible marks, and that is a reasonable trade to make before a wedding.
And the Marbella point again, because it matters more for this wavelength than for most: melanin competes with blood for green light. Treated skin that then catches the sun is the main route to a pigmentary problem. There are months on this coast when we would rather treat you in Denmark.
Questions
Good to know
If your question is not here, ask it in the enquiry form — Dr. Henningsen answers these personally.
Ask a question- Is this the same as a CO2 laser?
- Will it work on an old, white scar?
No. The treatment works by heating the blood inside the vessels that make a scar look red. Once a scar has turned pale there is no longer a target for this wavelength, and the energy has nothing useful to do. Mature scars are a question of contour and texture, which is a different set of instruments.
- Will it get rid of my stretch marks?
It can reduce the redness of stretch marks while they are still red, and that is a real improvement — but it does not rebuild the torn framework underneath, so the furrow stays. If what bothers you most is the colour, this is the right instrument. If it is the texture, it is not, and we will say so at the consultation rather than sell you a course.
- How soon after surgery can a scar be treated?
Once the wound is closed and the sutures are out, and provided there is no infection. The published trials treated scars during the immature, red phase rather than waiting for them to settle, because that is the window in which the colour is still driven by vessels. Dr. Henningsen will look at the wound before setting a date.
- Does it hurt?
Most people describe a brief snap, like a rubber band, with the cooling taking most of the sting out. In the head-to-head trial against the pulsed dye laser there was no significant difference in pain scores between the two. Anaesthetic is not usually needed.
Consultation
Ready to talk about your skin?
Consultations with Dr. Henningsen are arranged individually. Tell us what you would like to change and we will come back to you with the options, the honest downtime and the realistic result.