Laser and light-based technologies have fast become go-to treatments for skin rejuvenation and cosmetic enhancement – including fractional, ablative and non-ablative treatment options.
The healing power of light has been recognised and used for thousands of years, dating back to the Ancient Greeks and Romans. Over the millennia, our understanding and use of light-based therapies have continually evolved to optimise results, reduce downtime and treat a wide range of skin conditions and ageing concerns. For cosmetic indications – from treating wrinkles, pigmentation and stretch marks to scars, tattoo removal and hair reduction – light-based treatments can be broadly categorised as laser, IPL, LED and photodynamic therapy.
What is a laser?
In 1917 Albert Einstein theorised on the stimulated emission of radiation, or what we commonly refer to as lasers. Today lasers are used in a multitude of products and systems – from CD players to barcode scanners. Laser is an acronym for Light Amplification for the Stimulated Emission of Radiation and is used in the cosmetic enhancement and beauty industries for an array of treatments, ranging from the correction of skin irregularities, pigmentation and wrinkles to hair reduction and tattoo removal.
Lasers work by selecting a wavelength that is readily absorbed by the target tissue. The target tissue is heated to a temperature high enough to destroy it without damaging the adjacent normal tissue. The laser emits a single frequency of light with all the lightwaves going in the same direction, allowing the target tissue to absorb the maximum amount of heat. The target tissue is all-important when treating skin problems with a laser: for pigmentation it is melanin; for spider veins it is blood; and for wrinkles it is water. Each of these target tissues absorbs a different wavelength of light, meaning a different laser is needed for each specific problem.
So why does absorbing light treat a problem? The light energy is transformed into heat energy. This energy heats the chromophore and causes damage. In the case of hair removal, it heats up the hair follicle to a critical temperature that causes irreversible damage to the hair follicle and only the hair follicle. Surrounding structures will be heated but not to a level where they are irreversibly damaged, otherwise blistering will appear.
For blood vessels, the haemoglobin is targeted by green or yellow light as these wavelengths are predominantly absorbed by blood. The heat causes clotting, coagulation and the closing down of small vessels. For resurfacing the skin, the target tissue is water. The laser delivers enough energy to heat the water in skin, vaporising it and in turn vaporising skin tissue. Similarly, with each treatment the heat causes damage of the target tissue, creating the desired result.
However, without energy (measured in watts) to deliver the wavelength nothing will happen. More energy increases the heat and damage, so there is a trade-off.
One of the special qualities of laser light is its ability to be pulsed. Often the beam can target the chromophore for long enough to heat it, stopping before surrounding tissues absorb too much of the light, then this process is repeated. The duration of pulse is proportionate to the size of the target.
The main differences between lasers have to do with the wavelength of the light emitted by the device. What you need to know is that different laser wavelengths – which equate to different colours of light – can target different concerns.
Many different materials may be used as the laser medium, and the laser type, is commonly known by the particular medium used. For example, lasers used in cosmetic procedures frequently include carbon dioxide (gas), dye (liquid) or Neodymium:YAG (solid).
Each medium produces light of a particular wavelength or, in terms of visible light, colour. The entire range of potential colours, from ultraviolet to radio waves, is known as the electromagnetic spectrum.
It is important to note that the ‘YAG’ in many laser types describes not the lasing medium, but the matrix of Yttrium Aluminium Garnet in which the lasing atoms are held. This is a clear, glass-like material that is transparent to visible and near-infrared wavelengths.
Most lasers operate in one of two principal modes. The first is Continuous Wave (CW), which refers to a laser beam that is present continuously throughout operation.
The second principal mode is referred to as pulsed mode, where the laser energy is not continuous but released entirely over a very short time, such as a millionth of a second. An example is the Q-switched laser. This allows for much higher levels of energy to be used than with CW.
The beam may also be turned off mechanically or electronically for brief periods (for example, on for a second, then off for half a second). This is often called pulsed CW mode.
When laser light is absorbed by the skin it is converted to heat, which can result in the burning, vaporisation or coagulation of the targeted tissue. In this respect, lasers can be further divided into two basic types: ablative and non-ablative.
Because laser treatments use heat, a mild to moderate burning sensation is experienced during treatment and slight swelling and redness afterwards. This can be covered with makeup and normally subsides in a few days, depending on the level of treatment administered.
Ablative and fractionated laser treatments can be administered only by qualified cosmetic doctors.
Always ask how new the laser is, when it was purchased and when it was last checked by the manufacturer. Recent models are far superior to earlier ones in terms of achieving predictable and precise results with less downtime.
Ablative lasers
Ablative lasers, notably carbon dioxide (CO2) and Erbium:YAG, use a process where the upper layers of aged or damaged skin are vaporised by a deep, single wavelength of energy to remove and resurface the skin, either superficially or through to the deeper layers.
It is this damage that stimulates the healing and restructuring of the skin, resulting in a more even complexion and a significant reduction in lines and wrinkles.
These lasers are often used to remove deep lines or scars as well as to improve overall skin tone and texture and typically require only one session. They do need anaesthetic, or some form of pain management and incur downtime during which the skin will crust over, shed the scabs and fully heal.
The oldest type of ablative laser is the CO2 laser, which is still considered by many practitioners as the gold standard for dramatic cosmetic improvement. These carbon dioxide lasers can dramatically reduce wrinkles, but downtime and side effects such as redness and peeling are extended, usually taking many weeks to heal. Erbium lasers have a great accuracy with fewer side effects but cannot treat deep wrinkles as successfully.
Non-ablative lasers
Non-ablative lasers use wavelengths which do not burn away skin and are suitable for the treatment of melasma, scarring, fine lines and wrinkles and typically do not require any downtime. This type of laser does not damage the skin, which can be considered an advantage, but may be less effective and require multiple sessions.
Non-ablative lasers are commonly used to correct certain skin concerns, remove tattoos and reduce hair by targeting the dark pigments.
Fractionated laser technology
The advent of fractionated laser, where microscopic columns of skin are treated while surrounding skin is left intact, has made it possible to achieve results comparable to traditional CO2 laser resurfacing with fewer side effects and profoundly less downtime.
Fractional skin resurfacing can utilise both non-ablative and ablative laser systems – the breakthrough difference of this technology is the fractionated delivery system of light. All fractional resurfacing follows the same premise: the laser beam is broken up, or fractionated, into many small microbeams. When these beams strike the skin’s surface, only small areas of the skin are damaged, leaving the surrounding skin intact. These small areas of undamaged skin promote much more rapid re-epithelialisation, recovery and healing, which promotes new collagen production and facial skin rejuvenation.
The applications for fractional laser technology include overall facial rejuvenation, improving evenness of skin tone and texture, reducing pore size, improving the appearance of lines and wrinkles and helping to reverse the effects of sun damage. A more mild treatment may take several sessions, while one procedure is usually sufficient for a more aggressive treatment.
