Key facts
- Skin types
- Fitzpatrick III to V: more epidermal melanin competes for incoming laser energy
- Main risk
- Post-inflammatory hyperpigmentation: darkening after inflammation, often weeks after treatment
- Picosecond pulse
- Pigment is fragmented mainly by a pressure effect, with less heat reaching surrounding skin
- Settings that matter
- Wavelength, fluence, spot size, number of passes and interval between visits
- Sun
- Singapore's UV is high year-round; a recent tan or sunburn means treatment is deferred
- Melasma
- Heat is a trigger; laser is conservative and one part of a longer plan
- Test spot
- A small area treated first where the reaction is uncertain; advised or not at assessment
Why does Asian skin react differently to pico laser?
Because more melanin sits in the epidermis, competing for the energy. In Fitzpatrick III to V skin, the range that describes most patients in Singapore, melanin at the surface absorbs part of the laser energy before it reaches the target pigment. More of that energy is deposited as heat in the epidermis, and heat is what inflames skin. General references such as DermNet describe darker skin tones as more susceptible to side effects from laser treatment, which is why settings are chosen for the skin rather than copied from a default.
The usual consequence is post-inflammatory hyperpigmentation, or PIH: melanocytes respond to inflammation by making pigment, and in more reactive skin the response is brisk and can persist for months. It often appears with a delay, because skin can look cleaner straight after treatment and darken over the following weeks. The skin-of-colour literature describes PIH as affecting darker-skinned patients with greater frequency and severity, which is why it is the risk to plan around.
A picosecond pulse lasts a trillionth of a second, short enough that pigment is fragmented mainly by a pressure effect before much heat can spread. That is the mechanistic case for a picosecond laser in this population. It is a difference in how energy is delivered, not a promise about what will happen to a given face, and it does not remove the need for careful settings. The guide to what the picosecond pulse does covers the physics in more detail.
What do fluence, spot size and wavelength actually control?
Fluence is the energy delivered per unit area of skin, and it is the setting that most directly decides how much heat a pulse leaves behind. Raising it can clear a sun spot more decisively and can also inflame the surrounding skin; in melanin-rich skin the margin between the two is narrower. Which fluence is appropriate depends on the pigment, its depth, the wavelength and the skin's reactivity, so no figure is quoted here and none should be copied from one patient to another.
Spot size changes how the beam behaves in tissue. In general, a larger spot lets the beam reach deeper before it scatters, while a smaller spot concentrates energy nearer the surface and allows finer work on discrete marks. The DEKA TORO used for Dr Sin Yong's T2 Frax Radiance protocol offers spot sizes from 2 mm to 6 mm, with a beam profile designed for even distribution of energy across the spot. Wavelength sets how strongly melanin absorbs the light and how far it travels: 532 nm is absorbed strongly and stays superficial, 1064 nm travels further and is the more conservative choice in darker skin, and 785 nm sits between them.
Passes and the interval between visits belong on the same list. Pigment treatment is staged so the skin's response can be read before the next step, and laser toning is not run on an open-ended schedule, because pale spots have been reported after frequent repeated toning of the same area.
“A pico laser breaks up pigment that is already there. It does nothing about the reason your skin made it — which is why melasma comes back and a sun spot usually does not.”
Dr Sin YongOn what the technology does and does not reach
What is a test spot, and when is it used?
A test spot is a small area treated first so that the skin's reaction can be watched before a larger area is treated. It is a precaution for situations where there is real doubt about how the skin will respond, for example after a recent tan, after darkening following an earlier laser, or where the pigment is mixed or its depth is uncertain. Whether one is advised for you is decided at assessment, not assumed.
The limit of a test spot is that skin can look calm for days and darken later, so a useful test is read after the delay in which PIH appears, not the next morning. It also tests just the setting used on that spot: a different wavelength, a larger area or a fractional mode is a different exposure. A test spot lowers uncertainty; it does not remove it. The table lists the settings worth asking about.
Pico laser settings: what each controls and what to ask about it| Setting | What it controls | What to ask |
|---|
| Wavelength | How strongly melanin absorbs the light and how deep it reaches | Which wavelength suits my pigment and its depth? |
| Fluence | Energy per unit area; the main driver of heat and inflammation | How is it set for my skin type, and who adjusts it? |
| Spot size | How deep and how finely the beam works in tissue | Why this spot size for this mark or area? |
| Passes and interval | How much energy the skin receives, and how often | How will visits be paced, and how will you decide to stop? |
| Mode | Spot, toning or fractional delivery act on different targets | Which mode is this, and what is it aimed at? |
How does Singapore's sun change the plan?
Singapore sits roughly one degree north of the equator, so UV is high year-round with no seasonal low. For pigment work that has two consequences. Skin that has been tanned is more reactive, so treatment is deferred after a recent tan or sunburn. And sun exposure between visits can restore pigment faster than any laser clears it, because ultraviolet stimulates new melanin.
Daily broad-spectrum sun protection is therefore part of the treatment, not an accessory, and it begins before the first visit. For melasma, visible light and heat are triggers in their own right, which is why tinted formulations containing iron oxides are commonly used. Aggressive exfoliation and high-strength actives are set aside while the skin settles, and specific aftercare is given for the mode used.
Why is melasma treated differently from sun spots?
Melasma is a chronic condition with hormonal, vascular and ultraviolet drivers, and it is sensitive to heat. Infrared and visible light are triggers in their own right, so a hot commute, a kitchen or a heat-generating laser applied to the wrong diagnosis can all contribute. A setting that clears a sun spot decisively can leave melasma darker.
Where laser has a role in melasma it is conservative: typically low-fluence 1064 nm work, a deeper-penetrating wavelength at gentle energies that spares the melanin-rich epidermis, as one component of a plan built on photoprotection and topical therapy. The pigment can be reduced, but the mechanism producing it continues, which is why melasma tends to return while a sun spot usually does not. Telling the two apart before treatment is the first step, and the melasma treatment page sets out the full plan.
What are the risks, and who should wait?
Redness, warmth and mild swelling are expected, and over pigmented spots the mark usually darkens and may crust before it sheds. Less common effects relate to settings, interval and skin type: PIH, pale spots after frequent repeated treatment, blistering or pinpoint bleeding at higher energies or in fractional mode, and melasma rebounding darker if it is treated aggressively. Darkening after treatment usually fades with time and photoprotection, but that can take months.
Treatment is deferred or reconsidered with a recent tan, active infection or inflammation in the area, photosensitising medication, a tendency to keloid scarring, and in pregnancy. Any pigmented spot that is changing in size, shape or colour, bleeding or unlike the others is examined first and referred for dermatological assessment before laser is considered. If skin darkens after laser, the instruction is to stop adding energy, protect the skin from the sun and have the pigment reassessed; the page on pigmentation worse after laser sets out that sequence.
Contact the clinic if you see blistering, thick yellow or oozing crusts, or pain, swelling or warmth that increases instead of settling. The complication care page lists which signs need same-day attention.
What should you ask before having pico laser?
Ask what the pigment is: a sun spot, a post-inflammatory mark, melasma or a mixture, and how the doctor knows. Ask which wavelength and mode will be used and why, how the fluence and spot size are set for your skin type, and whether a test spot is advised. Ask how visits will be paced, how the doctor will decide when to stop, what the aftercare is and what happens if the skin darkens.
Ask also who performs the treatment and who adjusts the energy during it. At this practice Dr Sin Yong performs every treatment himself, pico laser is delivered as the T2 Frax Radiance protocol on the DEKA TORO, and settings are chosen for Fitzpatrick III to V skin. The fee depends on the area, what the assessment finds the pigment to be, the mode and wavelength, and how the plan is staged. It is set out at consultation, and the how we quote page explains the pattern.
