Optimal clinical outcomes rely on precisely matching laser physics to tissue resistance. Because keloids are physically denser and more fibrous than hypertrophic scars, they require significantly higher energy output (typically around 20W) and longer dwell times to penetrate the tissue. Conversely, treating hypertrophic scars requires a moderated approach (around 12W) to stimulate remodeling without causing excessive thermal damage.
Core Takeaway: The necessity for parameter adjustment stems from the disparate fibrotic density of the two scar types. Keloids require aggressive energy levels to penetrate hard tissue and disrupt vascular supply, while hypertrophic scars require lower energy to ensure safety and prevent adverse reactions.
The Physics of Tissue Resistance
Analyzing Fibrosis Levels
The primary differentiator between these scar types is the density of the fibrous tissue.
Keloids exhibit high levels of fibrosis and greater volume, resulting in a physically harder mass. This density acts as a barrier, resisting laser penetration.
Hypertrophic scars, while elevated, generally possess a softer consistency and lower volume than keloids. They offer less physical resistance to thermal energy.
The Role of Tissue Thickness
The thickness of the scar tissue dictates the required therapeutic depth.
To be effective, the laser energy must reach the base of the scar tissue. In thick keloids, superficial treatment is ineffective; the energy must be calibrated to "drill" deeper into the dermis.
Calibrating Energy and Duration
Adjusting Power Output (Watts)
High-precision equipment allows for the fine-tuning of energy output to overcome tissue hardness.
For dense keloid tissue, a higher energy setting, such as 20W, is typically necessary. This power level ensures the beam creates sufficiently deep channels for remodeling.
For hypertrophic scars, energy is typically dialed back to approximately 12W. This lower setting preserves clinical efficacy while respecting the tissue's lower heat tolerance.
Modifying Dwell Time
Dwell time (measured in microseconds) refers to how long the laser beam remains on a specific point.
Keloids require longer dwell times. By maintaining the beam on a specific spot longer, the system delivers more total energy to penetrate the dense fibrous mass.
Hypertrophic scars require shorter dwell times to prevent heat from spreading laterally and damaging healthy surrounding tissue.
Strategic Goals by Scar Type
Mechanisms of Action for Keloids
The goal in treating keloids is often destruction and vascular disruption.
By increasing energy density (to levels such as 8-10 J/cm²) and reducing spot size (e.g., to 7 mm), the laser can penetrate deep microvascular nodes.
This aggressive approach is designed to cut off the nutrient supply, inhibiting the continuous proliferation of fibroblasts typical in keloids.
Mechanisms of Action for Hypertrophic Scars
The goal for hypertrophic scars is controlled remodeling.
The lower energy settings aim to initiate collagen reorganization without triggering an aggressive inflammatory response.
This approach improves texture and pliability while minimizing the risk of worsening the scar.
Understanding the Trade-offs
The Risk of Over-treatment
Using keloid-specific settings on a hypertrophic scar is a critical error.
Applying high wattage (20W) and long dwell times to softer hypertrophic tissue can lead to adverse reactions, including burns and abnormal pigmentation.
This is particularly risky in patients with darker skin tones, where excessive energy absorption can cause permanent damage.
The Risk of Under-treatment
Conversely, using conservative settings on a keloid will likely result in treatment failure.
Low energy (12W) may not penetrate the fibrotic "shield" of a keloid.
This results in a superficial injury that fails to reach the deep vascular network, rendering the treatment ineffective at stopping scar growth.
Making the Right Choice for Your Goal
To ensure safety and efficacy, clinicians must assess the physical properties of the scar before touching the control panel.
- If your primary focus is treating Keloids: Prioritize high energy density (20W) and longer dwell times to penetrate dense fibrosis and disrupt the vascular nutrient supply.
- If your primary focus is treating Hypertrophic Scars: Prioritize moderate energy (12W) and shorter dwell times to stimulate remodeling while actively protecting against thermal burns.
Success in laser scar revision is not defined by the power of the machine, but by the precision with which that power is matched to the density of the tissue.
Summary Table:
| Feature | Keloid Treatment (Dense Fibrosis) | Hypertrophic Scar (Moderate Fibrosis) |
|---|---|---|
| Recommended Power | High Energy (~20W) | Moderate Energy (~12W) |
| Dwell Time | Longer (Deep Penetration) | Shorter (Thermal Protection) |
| Primary Goal | Vascular Disruption & Destruction | Controlled Collagen Remodeling |
| Risk Factor | Under-treatment (No Penetration) | Over-treatment (Burns/Pigmentation) |
| Spot Size | Reduced (7 mm for Density) | Standard for Surface Area |
Precision is the key to clinical excellence in scar revision. BELIS specializes in professional-grade medical aesthetic equipment designed exclusively for clinics and premium salons. Our advanced laser systems, including CO2 Fractional, Nd:YAG, and Pico lasers, provide the fine-tuned control needed to switch seamlessly between aggressive keloid protocols and gentle hypertrophic remodeling. Whether you are expanding your services with HIFU, Microneedle RF, or body sculpting solutions like EMSlim, BELIS delivers the technology and training to ensure your patients achieve superior results safely. Contact us today to equip your clinic with the industry's most precise laser and skincare technology.
References
- Hanan Hassan Sabry, Eman Ahmed Ibrahim. Comparative Study between Intralesional and Topical Botulinum Toxin A Combined with Fractional Carbon Dioxide Laser in Treatment of Hypertrophic Scars and Keloids (Comparative study). DOI: 10.21608/bjas.2020.135964
This article is also based on technical information from Belislaser Knowledge Base .
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