Laser and Light-Based Therapies
Medical laser and light-based therapies use optical radiation to act precisely on diseased tissue or to stimulate the skin's own repair processes. At Haute-Derma, light-based treatment is more than running a device on preset settings. It means understanding how heat behaves in tissue and tailoring every parameter (wavelength, pulse duration, fluence and spot size) to the individual skin type and the lesion being treated.
Physical and Biological Principles
Selective Photothermolysis
Described by Anderson and Parrish in 1983, this principle underpins every modern laser treatment. To destroy a target (the chromophore) while sparing the healthy tissue around it, three conditions must be met:
- Wavelength (λ): must match, or lie close to, an absorption peak of the target chromophore.
- Pulse duration (τ): must be equal to or shorter than the thermal relaxation time (TRT) of the target, so that heat does not spread to surrounding healthy cells.
- Fluence (J/cm²): must be high enough to raise the target to a temperature that causes biological destruction.
Target Chromophores in the Skin
- Melanin: absorbs across 280–1200 nm, with absorption falling as wavelength increases. It is the target when treating melasma, freckles, unwanted hair and dark tattoo ink.
- Hemoglobin (oxyhemoglobin/deoxyhemoglobin): absorption peaks at 418 nm, 542 nm and 577 nm, plus a secondary band at 940–1064 nm. It is the target when treating dilated vessels, hemangiomas and red birthmarks.
- Water (H₂O): strong absorption in the far infrared (2940 nm and 10,600 nm). It is the target for ablative lasers, resurfacing and tissue debridement.
Why Spot Size Matters
At the same fluence, a large spot (8–10 mm) loses less light to scattering in the epidermis than a small spot (2–3 mm), so photons reach deeper into the dermis.
Clinical Laser and Light Technologies at Haute-Derma
| Technology / Device | Wavelength | Clinical Indications |
|---|---|---|
| Fractional CO2 laser | 10,600 nm | Atrophic scars, advanced photoaging, ablation of benign lesions |
| Er:YAG laser | 2,940 nm | Superficial rejuvenation, fine wrinkles, scar revision |
| Q-switched / picosecond Nd:YAG laser | 1064 nm / 532 nm | Melasma, nevus of Ota, tattoo removal, hypopigmentation |
| Diode / alexandrite laser | 808 nm / 755 nm | Permanent hair reduction, superficial pigmented lesions |
| Long-pulse Nd:YAG laser | 1064 nm | Leg veins, red inflamed acne, non-ablative rejuvenation |
| Intense pulsed light (IPL) | 400–1200 nm (polychromatic) | Photorejuvenation, hair removal, rosacea redness |
| LED light therapy | 415 nm / 633 nm | Antibacterial action in acne (C. acnes), reducing inflammation, wound healing |
Clinical Safety and Complication Management at Haute-Derma
Vietnamese skin (Fitzpatrick types IV–V) has a high density of epidermal melanin, which sharply raises the risk of unwanted heat absorption and post-inflammatory hyperpigmentation (PIH). Haute-Derma follows a three-layer safety protocol:
- Epidermal cooling: a cold-air cryo system (−30°C) or a continuously chilled sapphire contact tip keeps the epidermis below 10°C throughout pulse delivery.
- Pre-treatment skin conditioning: patients at high risk of PIH are prescribed tyrosinase-inhibiting agents (such as tranexamic acid, niacinamide and arbutin) for 2–4 weeks before laser treatment.
- Shifting from photothermal to photomechanical effects: for pigment, we favor picosecond lasers, whose pulses last trillionths of a second. They shatter pigment with a mechanical shock wave rather than heat, keeping burning and darkening of the skin to a minimum.
