Allie Anderson speaks to practitioners about the various modes and functions of light-based treatments that are routinely used for a number of aesthetic indications
Light-based technologies have, over the years, become commonplace in medical and aesthetic clinics as the treatment of choice for a range of problems, from hyperpigmentation and fine lines to acne scarring and skin cancer. Some of the most established modalities are lasers, light-emitting diode (LED) therapy, intense pulsed light (IPL) therapy and photodynamic therapy (PDT), which are discussed in turn herein.
“Every laser device can do something different,” explains Mr Taimur Shoaib, who uses 10 lasers in his clinic. “Some treatments are good for the skin’s surface, some for segments of the skin a little bit deeper, and some for even deeper skin treatments. There are so many different areas of the skin that we can treat, such as bacteria and fine lines and wrinkles at the top of the skin, hair follicles at the bottom, and sun damage in the middle. Each laser system has to be quite specialised in order to deliver the treatment to the area concerned.” The molecules in the skin contain substances called chromophores, which are responsible for the molecule’s colour and which absorb light. When a wavelength of light is applied to the skin, it selectively targets a particular chromophore, which then absorbs the light. The light is then turned into heat energy sufficient to break down the target. In other words, it damages the chromophore.2 The way a wavelength of light affects the skin is in part determined by how deep beneath the skin’s surface it penetrates. The longer the light’s wavelength, the deeper it will penetrate. Therefore, different wavelengths with a different absorption coefficient will target a particular chromophore at a particular depth.3
There are three major chromophores in human skin, which are each associated with different indications that are treatable with lasers:
|Indication||Chromophore involved||Wavelength (nanometres)|
Figure 1: wavelengths targeting three main chromophores for various indications4,6
Other types of light-based treatment use incoherent light, where the photons do not travel in a unified manner, changing phase randomly. As a result, the light spreads over a wider area rather than being concentrated. Thus, even at a high power, incoherent light is transmitted over shorter distances and doesn’t penetrate as deeply as coherent light.6 An example of an incoherent light source is LEDs. LEDs are tiny light bulbs that emit non- thermal, visible wavelengths of light. The treatment covers a larger area than a laser, but being more diffuse also means it needs to be applied to the skin for longer.6 However, LED is used successfully to treat many of the same indications, with anecdotally good results. Lisa Monaghan-Jones is a proponent of this type of treatment, which she performs at her practice – Internal Beauty Clinic in Huddersfield.
“I choose LED phototherapy because it’s clinically proven technology-wise, it has guaranteed results and it’s suitable for all skin types,” she says. “It promotes regeneration and healing on the skin, so it increases collagen, enhances the function of enzyme repair, helps the lymph system, and stimulates new capillaries and new cell growth.” LED is indicated for a range of problems, she says, including acne, eczema, psoriasis, rosacea, pigmentation and ageing skin, as well as to promote healing after radiofrequency treatment, laser treatment, peels and surgery. Dr Rekha Tailor, medical director of Health + Aesthetics in Surrey, uses the same LED treatment protocol, whereby three different coloured lights of specific wavelengths work to combat different skin concerns. “It uses red light at 633 nm to reduce lines and improve tone and texture. It stimulates the fibroblast cells, which triggers the production of collagen and elastin, increases hydration and plumps up the skin,” she explains. “Blue light, which is 415 nm, can help to treat acne by damaging porphyrins, which naturally occur in acne bacteria. It reduces active acne and helps prevent break-outs, by normalising oil production.”
An 830 nm near-infrared light has a similar effect, Dr Tailor adds, while also soothing redness and irritation, thereby accelerating skin healing. Alternatively, Dr Ahn Nguyen advocates the use of a lay-in device that is fully automated and does not require staff to be present. She explains that it uses blue light at 470 nm to target acne and blemishes; red light at 660 nm to activate cells to produce collagen and elastin, as well as to reduce inflammation and redness associated with rosacea; and, as an additional benefit, infrared light at 940 nm to relieve muscle and joint pain, as well as the pain and stiffness associated with arthritis. “The device is suitable to be used before or after any other treatment to enhance the results of that treatment or to alleviate any side effects such as inflammation,” says Dr Nguyen, adding, “It can also be used to soothe skin immediately after IPL, laser or dermabrasion treatment.” While LED therapy can be used to treat all skin types, it can trigger seizures in patients with epilepsy7,8 and has not been trialled in pregnant women. It is also contraindicated in patients with porphyria,8 a rare hereditary disease affecting the metabolism of haemoglobin, as well as with certain medications.9
An adaptation of laser phototherapy comes in the form of IPL treatment. IPL works in the same way as a laser, but instead of emitting light of one specific wavelength, as lasers do, the light IPL produces is composed of a spectrum of colours from different wavelengths – commonly 550 to 950 nm. As a result, it can select different targets for absorption, much like using a number of different lasers in a single treatment. Dr Maria Gonzalez from the Specialist Skin Clinic in Cardiff states that IPL has two main skin indications: a condition called poikiloderma of Civatte, whereby (mainly female) patients present with erythema and mottled pigmentation on the neck as a result of sun damage; and red-coloured sun damage on the chest. “These treatments tend to be suitable for patients who are very fair skinned – typically Fitzpatrick skin types I and II – so people who have fair skin and eyes and burn easily in the sun,” she comments. Conversely, she explains, IPL is not suitable for those with olive-toned, Asian or black skin, particularly type VI, who, according to Dr Gonzalez, don’t suffer from these conditions anyway. Dr Gonzalez suggests that the advantage of IPL is that one machine, in its nature, can treat all manner of indications. “With lasers, you have to use a different one for each distinctive problem, which makes it a very expensive way to set up a clinic,” she says. “On the other hand, a laser tends to be able to produce extremely good results for specific, individual problems.” IPL has also been shown to be safe and effective in treating specific concerns, including vascular and pigmented lesions, photo-ageing, and skin conditions such as acne, rosacea and non-melanoma skin cancers.12 Moreover, the results of IPL can be improved by using it in combination with other anti-ageing treatments. For example, IPL combined with botulinum toxin injections has been shown to produce better results in correcting wrinkles that appear when the face is animated or in motion, called dynamic rhytids, than using IPL alone.13
PTD is a treatment that uses a drug called a photosensitising agent, combined with a particular wavelength of light, such that when the photosensitising agent is exposed to that light wavelength, it produces a form of oxygen that kills adjacent cells. PTD is licenced for treating non-melanoma skin cancers,14 with evidence demonstrating that PTD has significantly better outcomes for actinic keratosis, superficial and nodular basal cell carcinoma, and squamous cell in situ (known as Bowen’s disease) than other standard treatments.15 Nurse prescriber and aesthetic practitioner Anna Baker performs this treatment protocol using a topical photosensitising agent methyl- aminolevulinate (MAL, known as Metvix). Baker explains how the procedure works, “Metvix is applied to the skin cancer lesion, and left under an occlusive dressing for three hours, during which time the patient can go off and do what they want to do. The drug is very selective and only binds to certain kinds of cells – dysplastic or neoplastic cells – within the lesion, in which uptake of the drug is rapid. During that three-hour timeframe, these cells become saturated with photoactive porphyrins.” When the wavelength of light is applied later and mixes with these porphyrins, a chemical response is generated, the by-product of which is a form of oxygen called singlet oxygen, which in turn breaks down the damaged cells in the lesion. Sometimes, a small amount of the photosensitising agent is taken up by healthy tissue around the dysplastic or neoplastic cells, but this is minimal. The treatment uses a red LED light with a wavelength of around 630 nm, administered after the area to which the drug has been applied has been cleansed thoroughly. “This light wavelength is typically capable of treating an area roughly around 6x16cm,” Baker adds, “but this is very much dependent on how much patients can tolerate in one session.” One advantage here is that PTD can be repeated as often as is required – particularly useful in cases of field cancerisation, in which multiple lesions cover large areas. “We treat these patients on a maintenance basis, maybe every six months or every year, often for several years.” explains Baker. In addition, there is evidence that PTD can potentially delay the development of actinic keratosis and basal cell carcinoma, with limited evidence that it can prevent invasive squamous cell carcinoma.16 Interestingly, PTD has also been indicated for skin rejuvenation, in which aesthetic results can be significantly improved when combined with pre-treatment systems such as microneedling, microdermabrasion or fractional lasers.17
|Light colour||Main indication|
Main indication: rejuvenation
Main indication: acne
Main indication: deep pigmentation
The light-based technologies discussed are routinely used in a number of treatments and are safe and effective in skilled hands. However, severe adverse events can occur when administered by untrained practitioners: Mr Shoaib recalls treating a patient who had been left with a 4cm-diameter hole burnt into their skin due to poorly performed laser tattoo removal. “When you’re performing a treatment, you need to be able to look after and manage the side effects,” he says. That being the case, light-based skin treatments not only remain an established protocol for a range of medical and aesthetic indications, but also show a great deal of promise in treating many more in the future.