Ablative lasers briefly direct an intense burst of laser energy onto the surface of the skin. This energy heats water within the surface layers of the skin, causing both the water and the tissue of the skin to turn to vapour.
Every time the laser passes over the skin, some of the outermost layers of the skin are removed in a precise and controlled way to the appropriate depth.
The skin then heals over a period of time, as new layers of collagen are produced. The skin can literally resurface itself, causing an improvement in the appearance of sun damaged or acne scarred skin. After the treatment, the skin looks much healthier than it did previously.
This intensive treatment can significantly reduce the appearance of lines, wrinkles, and pigment (or skin colour) changes on the face, neck, and other parts of the body.
Ablative Lasers can be used in sensitive areas, such as lines around the lips, eyes and even eyelids, or over the whole of the face. Acne and other types of scars and certain stretch marks can also be improved.
Treatments with Ablative lasers usually require downtime as the laser targets the surface of the skin and not the dermal layer like non-ablative lasers.
Types of Ablative lasers:
CO2 (Carbon Dioxide Laser) – Operating at a wavelength of 10,600 nm, it is absorbed by tissue water causing temperature of the water to rise above 100 degrees C. The laser penetrates approx. 30um within the skin. Thermal injury is prevented when the laser pulsewidth is less that the thermal relaxation time of the tissue (the time required for 50% of the heat to diffuse). The critical pulsewidth is less that 1 millisecond.
With each pass of the laser, thermal necrosis increases slightly so it is important that the the thermal necrosis does not exceed a depth of 100um.
Fluence (energy density) rather that peak power is more clinically relevant to tissue ablation because it measures the energy (in J) delivered to the treatment area (cm2) based on the spot size. Increasing the fluence therefore increases the depth of ablation. The skin vaporisation threshold is approx. 5J/cm2. A fluence of 5-7J/cm2 provides clean and efficient tissue ablation.
The CO2 laser is suited to the treatment of perioral vertical furrows, crow’s feet and mild dermatochalasis, actinic damage, facial elastosis, shallow scars and epidermal lesions.
Er:Yag Laser – Er:Yag lasers operate at a wavelength of 2940nm. This wavelength corresponds to the main peak of water absorption. When compared with the CO2 laser, the Er:YAG laser is more efficiently absorbed by water-containing tissues and offers more precise tissue ablation with minimal thermal damage. This wavelength corresponds to the main peak of water absorption. When compared with the CO2 laser, the Er:YAG laser is more efficiently absorbed by water-containing tissues.
Pulses of 200 to 350 microseconds result in thermal necrosis lf less that 10um in depth. Unlike CO2 lasers, Er:Yag lasers injury depth remains stable. The vaporisation threshold of the Er:Yag laser is between 0.5 and 1.7J/cm2. The fluence and depth of tissue ablation are directly related therefore, for every J/cm2, 2 to 4 um of tissue depth is ablated.
Unlike the CO2 laser, Er:Yag appears safe for use on the neck, chest and hands. Er:Yag is well suited for the treatment of actinic damage, dyschromias, mild photodamaged skin, superficial rhytides.
Ablative lasers should not be used to treat active acne, deep acne pits or picks.