Key facts
- Subcision
- Subcutaneous incisionless surgery: a needle or blunt cannula divides the bands tethering a scar, leaving the surface intact
- Fractional CO2 laser
- Ablative 10,600 nm columns through the surface into the dermis; here as the S3 Resurfacing Lift on the DEKA Tetra Pro
- The stretch test
- A scar that flattens when the skin is stretched is a surface scar; one that stays pinned is tethered
- Sequence
- Release first, then resurfacing, RF microneedling or volume support where the plan calls for them
- Ice-pick scars
- Neither: narrow deep tracts are approached with TCA CROSS or point treatment
- Decided by
- Scar-by-scar examination under directed light, by Dr Sin Yong
What is the difference between subcision and laser for acne scars?
Subcision works beneath the scar; laser works on it from above. In subcision, a fine needle or blunt cannula is passed under a depressed scar, in the subcutaneous plane, and swept to divide the fibrous band that anchors the underside of the skin to deeper tissue. The surface is entered through a puncture, not cut. A fractional laser, by contrast, delivers columns of energy through the surface into the dermis, prompting the skin to heal and remodel the texture it can reach.
The two therefore answer different questions. Subcision asks whether something is pulling the scar down from inside; laser asks whether the surface and upper dermis can be remodelled into a smoother contour. Acne scar treatment starts by sorting the scars on a face into those two groups, because most faces carry both, and a single device applied to all of them improves some and leaves the rest exactly where they were.
Why can a laser not release a tethered scar?
Because the tether sits below the depth a resurfacing laser is meant to reach. A rolling scar is a broad, soft-edged dip held down by a cord of scar tissue running from the underside of the dermis into the subcutaneous fat, in the way a thread pulls an upholstery button into a cushion. Fractional CO2 energy ablates and heats columns of skin from the surface downward; it remodels collagen in the dermis, but it does not cut a fibrous band beneath it, and heating the dermis above a tether cannot make the tether let go.
That is the usual story behind a plateau: several rounds of laser, real improvement at first, then the same few depressions refusing to move. Those scars were never a surface problem. The guide to acne scar types describes the stretch test: pull the skin around the scar taut with two fingers, and a surface scar flattens while a tethered scar stays pinned. A pinned scar is a subcision question, however many passes of laser it has already had.
“You can resurface a tethered scar indefinitely. The tether keeps pulling it down.”
Dr Sin YongOn why laser alone plateaus on rolling scars
Which scar needs which: rolling, boxcar or ice-pick?
Rolling scars are tethered and need release; boxcar scars are mostly a surface and dermal problem; ice-pick scars are too narrow and deep for either and are approached with TCA CROSS or point treatment. A boxcar scar that stays pinned on stretching is the overlap: it is tethered as well as walled, and it is released before its walls are resurfaced. The four-question acne scar checker sorts the common patterns as a reading guide before the in-person stretch test.
Fractional resurfacing here is the S3 Resurfacing Lift on the DEKA Tetra Pro, which combines point shots into scar pits with fractional passes and is sequenced with subcision and TCA CROSS rather than used alone. RF microneedling is the other dermal tool for rolling and shallow boxcar scars once any tether is gone, and it is chosen over ablative laser where skin type or recovery argues for heat delivered beneath the surface. Flat red or brown marks are not textural scars and are treated as redness or pigment.
Raised scars are the one group where neither applies in the usual way: hypertrophic and keloid scars are injected or managed with silicone, and resurfacing a raised scar risks making it worse.
Subcision and laser compared by scar type| Scar type | Subcision | Fractional laser (S3 Resurfacing Lift) | Usual sequence |
|---|
| Rolling, pinned on stretching | Yes: divides the tethering band beneath the scar | Alone, cannot release the tether | Release first; resurface or RF microneedling afterwards |
| Boxcar, flattens on stretching | Not needed | Yes: remodels walls and base from above | Resurfacing or RF microneedling |
| Boxcar, stays pinned | Yes: tethered as well as walled | After release, for the walls | Release, then resurfacing |
| Ice-pick | No: too narrow and deep | Point shots into the pit, with TCA CROSS | TCA CROSS or point treatment first |
| Flat red or brown marks | No | No | Treated as redness or pigment, not as scars |
| Raised (hypertrophic or keloid) | No | No: resurfacing can worsen a raised scar | Injection or silicone, assessed separately |
In what order are subcision and laser done, and when are both used?
Release first, then resurface. Subcision frees the surface to sit level and creates a space beneath the scar in which new collagen forms; resurfacing then works on the texture that remains, and the two are spaced so that the skin has settled between them. Doing the laser first wastes the pass over a scar that is still being pulled down, and doing them in the same sitting adds surface injury to an area that is already bruised and swollen from release.
Both are used on most scarred faces, because most faces carry both scar types. Where a released scar is also volume-deficient, a small amount of filler or a collagen biostimulator may be placed into the freed space so that the band cannot re-form across it; that is a decision made at the time, not a routine add-on. Subcision in Singapore is a doctor-performed procedure under local anaesthetic, and Dr Sin Yong plans the sequence scar by scar.
Who should wait, and what are the risks of each?
Scar work is deferred while acne is still active, because new lesions keep making new scars, and with infection, a keloid tendency, isotretinoin use that has not been reviewed, a bleeding tendency and in pregnancy. A scar that is raised, changing or unusual is examined before anything is planned. Marked, widespread scarring beyond what release and resurfacing can improve is referred to a plastic surgery specialist for a surgical opinion.
Subcision brings bruising, swelling and tenderness that settle on their own, and, uncommonly, a small lump or nodule where blood collects beneath the released scar, which is reviewed. Fractional CO2 laser brings redness, crusting and a recovery that needs care, and in Fitzpatrick III to V skin the main risk is darkening afterwards, which settings, sun protection and pacing are designed to limit. The fee follows the number and type of scars, the steps planned and how they are staged; how fees are quoted explains the written quote given after assessment.
