Acne scars are a common concern for many patients, persisting long after breakouts have resolved.
Several energy-based technologies are used in aesthetic medicine to address different scar types, and the differences between them are clinically significant. Understanding which technology works at which tissue depth, and for which type of scar, is the starting point for any meaningful treatment conversation.
This article provides a factual overview of three technologies used for acne scar treatment — fractional ablative CO2 laser, Pico laser, and RF microneedling — as well as subcision, which is a procedural technique sometimes used alongside energy-based treatments. The goal is to help patients arrive at a consultation better informed about the options available and the clinical factors that guide treatment selection.
Understanding Acne Scars: Why Scar Type Matters
Acne scars are generally classified by their morphology and depth. The most clinically relevant categories on the face include:
Atrophic Scars
The most common type, resulting from a net loss of collagen during the healing process. Further subdivided into icepick scars (narrow, deep channels), boxcar scars (broad depressions with defined edges), and rolling scars (undulating surface caused in part by fibrous tethering beneath the skin).
Post-Inflammatory Hyperpigmentation (PIH)
Technically a pigmentary change rather than a structural scar, PIH appears as darkened patches following inflammation. It commonly coexists with atrophic scarring, particularly in patients with Fitzpatrick skin types III–V.
Hypertrophic or Keloid Scars
Caused by excess collagen production. Less common on the face, but present in some patients.
Because different scar types originate at different tissue depths and involve different biological processes, they respond differently to different treatment modalities. Accurate classification by a trained aesthetic doctor is therefore the necessary first step before any treatment plan is made.
How Each Technology Works
Fractional Ablative CO2 Laser
Fractional CO2 laser delivers columns of ablative laser energy in a controlled grid pattern. At each treatment point, the laser vaporises a column of skin tissue while leaving the surrounding skin intact. This approach stimulates a wound-healing response and new collagen formation at and around each treatment point, and also causes thermal stimulation of the surrounding tissue, further supporting collagen remodelling.
Because fractional CO2 laser acts at a meaningful tissue depth, it is generally considered suitable for moderate-to-severe atrophic scarring, particularly boxcar and rolling scars with significant depth. It also addresses surface texture irregularity and enlarged pores as secondary effects of the resurfacing process. The recovery period associated with fractional CO2 laser is typically longer than with non-ablative options — commonly 5–7 days of visible healing involving redness, swelling, and skin shedding, though this varies between individuals and protocols.
In Singapore's patient population, where Fitzpatrick skin types III–V are prevalent, the parameters of CO2 laser treatment must be carefully calibrated by the treating doctor to manage the risk of post-inflammatory hyperpigmentation (PIH). This is a clinically important consideration that requires experience with treating a range of skin types.
Pico Laser
Pico laser delivers energy in ultra-short pulses measured in picoseconds (trillionths of a second). When paired with a fractional microlens array (MLA), the laser creates focal points of laser-induced optical breakdown (LIOB) within the dermis, stimulating collagen and elastin production without ablating the skin surface. This non-ablative mechanism differs meaningfully from fractional CO2 laser: the skin surface remains intact, the recovery period is typically shorter (commonly 1–3 days of mild redness), and the risk of PIH is generally considered lower, making it a relevant option for a wider range of skin types.
Pico laser is commonly used for mild-to-moderate rolling and boxcar scars, post-inflammatory hyperpigmentation, uneven skin tone, and enlarged pores. Because the effect is cumulative, it is typically delivered as a series of sessions over time rather than as a single high-intensity treatment. It is also used as a refinement option following an initial course of CO2 laser resurfacing.
RF Microneedling (Morpheus8)
RF microneedling combines microneedling with fractional radiofrequency energy. Fine insulated needles penetrate the dermis and subdermal tissue at adjustable depths, delivering controlled RF energy at the target depth. The micro-injuries created by the needles trigger the skin's wound-healing response, while the RF energy stimulates collagen remodelling and new collagen formation within the dermis and subdermis.
For acne scarring, RF microneedling is particularly relevant for rolling scars — where fibrous tethering beneath the skin surface contributes to the characteristic undulating appearance — and for shallow boxcar scars. Because the RF energy is delivered subdermally rather than at the skin surface, epidermal disruption is limited and the risk of surface pigmentation changes is generally lower than with ablative laser. Downtime is typically in the range of 2–5 days. RF microneedling may also address early skin laxity and enlarged pores as secondary effects.
Subcision — A Procedural Technique, Not a Standalone Treatment
Subcision is a minor procedural technique in which a fine needle or cannula is used to mechanically disrupt the fibrous bands that tether rolling and certain boxcar scars to underlying tissue. By releasing this tethering, subcision may allow the depressed skin surface to rise, reducing shadowing and visible depth.
Subcision is typically used as a preparatory step in conjunction with energy-based treatment — for example, RF microneedling or Pico laser — rather than as a standalone procedure. Whether subcision is appropriate, and in what combination, is determined by the treating doctor on an individual basis following a clinical assessment of the patient's scar morphology.
Comparative Overview
The following table is a factual reference summary of how these treatment approaches differ in mechanism and clinical application. It is not a treatment recommendation and does not account for individual patient factors.
| Feature | CO2 Laser (Fractional Ablative) | Pico Laser (Non-Ablative Fractional) | RF Microneedling |
|---|---|---|---|
| Mechanism | Ablative columns + thermal stimulation | Photoacoustic LIOB in dermis | RF energy via insulated microneedles |
| Scar types typically addressed | Moderate–severe boxcar, rolling | Mild–moderate rolling, boxcar, PIH | Rolling, shallow boxcar |
| Addresses PIH / pigmentation | Partial; PIH risk requires management | Yes — relevant for PIH and tone | Not a primary indication |
| Skin surface disruption | Yes (ablative) | Minimal | Minimal |
| Typical downtime | 5–7 days | 1–3 days | 2–5 days |
| PIH risk in Asian skin types | Present; requires careful calibration | Generally lower | Generally low |
| Collagen stimulation | Significant (ablative + thermal) | Moderate (photoacoustic) | Significant (subdermal RF thermal) |
| Typical treatment approach | Single or spaced sessions | Series of sessions over time | Series of sessions over time |
Note: Downtime and response figures above are general references only. Individual outcomes vary based on skin type, treatment parameters, scar morphology, and individual healing response. This table is not a substitute for a clinical consultation.
Which Scar Type Is Each Approach Typically Used For?
The following is a general clinical reference. Treatment selection at Mirae is always based on a thorough in-person assessment by Dr Cherie Lau.
Fractional CO2 laser is typically considered for:
- Moderate-to-severe boxcar scars with well-defined edges
- Rolling scars of moderate depth
- Patients with significant surface texture irregularities where ablative resurfacing is clinically appropriate
- Patients with lighter Fitzpatrick skin types (I–III) where the risk-benefit profile of ablative treatment is more favourable
Pico laser is typically considered for:
- Mild-to-moderate rolling and boxcar scars
- Post-inflammatory hyperpigmentation alongside structural scarring
- Patients across a wider range of Fitzpatrick skin types where a non-ablative approach is preferred
- Patients with limited downtime availability who are suited to a series of sessions
- Refinement and maintenance following an initial course of ablative resurfacing
RF microneedling is typically considered for:
- Rolling scars with a fibrous tethering component (often combined with subcision)
- Patients with concurrent skin laxity or enlarged pores alongside acne scarring
- Cases where a subdermal remodelling approach with limited epidermal disruption is preferred
Can These Approaches Be Used Together?
In clinical practice, patients with complex scar presentations — for example, those with multiple scar types, concurrent PIH, or skin laxity alongside scarring — may be assessed for a multi-modality approach. For instance, subcision may be incorporated as a preparatory step for rolling scars with significant tethering before energy-based treatment is applied.
Whether a combination approach is appropriate, and in what sequence, is always determined by the treating doctor following individual clinical assessment. Combining treatments without proper clinical judgement carries its own risks.
Skin Type and Post-Inflammatory Hyperpigmentation in Singapore
A significant proportion of Singapore's patient population has Fitzpatrick skin types III–V. Patients with higher Fitzpatrick skin types have a greater baseline risk of post-inflammatory hyperpigmentation following any procedure that creates controlled skin injury. This does not exclude them from ablative or more intensive treatments, but it does mean that energy settings, pre-treatment preparation, and post-treatment care must be carefully managed by the treating doctor.
Pre-treatment protocols may include a course of topical agents to reduce baseline melanin activity before laser treatment is undertaken, depending on individual assessment.
Questions to Discuss During Your Consultation
A consultation with an aesthetic doctor for acne scar treatment should typically cover:
- What scar types are present and what is their severity?
- Is post-inflammatory hyperpigmentation present alongside structural scarring?
- What is your Fitzpatrick skin type, and what are the treatment implications?
- What recovery period can you realistically accommodate?
- How many sessions may be needed, and over what timeline?
- Are there any medical history considerations relevant to the proposed treatment?
All consultations are conducted by Dr Cherie Lau. The goal of the consultation is to give patients a clinically accurate and honest picture of what may be achievable for their specific skin, based on individual assessment.
Key Takeaway
Acne scar treatment is not one-size-fits-all. CO2 laser, Pico laser, and RF microneedling each address scarring through distinct mechanisms and at different tissue depths. The right approach depends on scar type, severity, skin type, and individual circumstances — all of which are assessed by Dr Cherie Lau during a thorough in-person consultation at Mirae Medical Aesthetics.
Medical Disclaimer: This article is intended for general educational purposes only. It does not constitute medical advice, a diagnosis, or a recommendation for any specific treatment. The information provided reflects general clinical knowledge and is not a substitute for an in-person consultation with a licensed aesthetic doctor. Individual suitability for any treatment can only be determined following a thorough assessment of each patient's skin concerns, medical history, and clinical presentation. Results from any aesthetic treatment vary between individuals and cannot be guaranteed. Please consult a qualified and licensed medical professional before proceeding with any aesthetic procedure.