Fractional resurfacing C02 and Er:YAG lasers have traditionally been used in ablative resurfacing procedures. They target tissue water and non-specifically ablate layers of skin to varying depths. Significant improvements can be obtained with these lasers in the treatment of scars (including those from acne vulgaris), cutaneous growths and photodamaged skin. However, recovery can be protracted and several side effects are recognized, including dyspigmentation, scarring and prolonged erythema. A new laser technology, fractional photothermolysis, has recently been introduced to specifically overcome the drawbacks of conventional resurfacing. Instead of producing one beam that causes uniform thermal damage to tissue in its path (as with conventional resurfacing lasers), the output from fractional resurfacing devices consists of thousands of microscopic columns, which each produce thermal damage to a small volume of tissue).
As ablation is non-confluent, the risk of scarring is reduced and recovery is rapid, with epidermal healing taking only 24 hours by means of keratinocyte migration.
Side effects last 24 to 48 hours, and consist mainly of erythema and oedema. The procedure can be performed under topical anaesthesia with slight discomfort.
Although promising, this technology is still in its infancy and optimum treatment frequency and parameters remain to be defined. The original fractionated laser Fraxel (Reliant Technologies, Mountain View, CA, USA) was a non ablative technique, interest is increasing in the delivery of ablative wavelengths in this way with fractionated Er:YAG and CO2 laser sources.
Pneumatic suction devices
Pneumatic suction devices are a recent enhancement to existing lasers and IPLs. A negative pressure is applied to the skin before the light pulse is delivered. This gently pulls and stretches the skin so as to thin the epidermis, reduce the density of epidermal melanin and bring the dermis closer to the light source. As a result, lower energies are required, and there is theoretically a lower propensity for side effects. The vacuum also activates sensory fibres, thereby reducing the transmission of pain and treatment becomes more comfortable. Negative pressure may also increase the volume of dermal vessels.
Expanded vessels concentrate laser energy better as they contain more blood this may be of assistance in treating therapy resistant lesions such as PWS. Pneumatic suction devices may be integrated into the laser or IPL handpiece (e.g. Aesthera PPx, Pleasanton, CA, USA) or as a separate attachment that can be used with existing systems (e.g. Inolase, Candela Corp, Boston, USA). Investigative clinical uses include hair removal, acne and analgesia in various procedures.
Optical clearing agents
A significant proportion of the light emitted by lasers is scattered by the epidermis.
Non-human and laboratory data have shown that hyperosmotic chemicals such as glycerol and propylene glycol enhance penetration of light to dermal targets by reducing scattering in the epidermis. This has the potential of improving the efficacy of lasers and reducing unwanted epidermal injury. Optical clearing agents are currently impractical to use in the clinical context, and refinements in the epidermal delivery mechanism of these agents are awaited.
