Breaking down the science of laser treatments with a doctor

Breaking down the science of laser treatments with a doctor

Laser beams

Text: Rachel Ho

Dr Rachel Ho of La Clinic gives us an education on the ins and outs of laser treatments in Singapore, and what you need to know before you begin any programme

Many people get quite confused when it comes to deciphering laser treatments on offer for skin rejuvenation, hair or tattoo removal. With so many places in Singapore, from doctor’s clinics to beauty spas offering laser treatments or Intense Pulsed Light (IPL) hair removal, it can get baffling trying to figure out why these treatments differ so greatly in the price, the number of sessions required and even safety standards. How is it that some ‘lasers’ can be used by beauty therapists while others require the care and attention of a trained doctor? And are we unwittingly putting our skin at risk when we unknowingly try out certain treatments and machines? 

Let’s start by defining what a laser treatment is. It is a medical therapy that uses a high intensity of focused light. This light energy is focused into powerful beams; which then allows the laser to treat various dermatological conditions like pigmentation, tattoos that you wish to remove, acne scars and visible pores.

The word laser is itself an acronym that stands for Light Amplified by Stimulated Emission of Radiation. Each type of laser is derived from light of a certain wavelength; which then gives this laser its specific properties. It is these properties (and wavelength) that determines whether a laser is best used to treat a specific condition.

Why are there so many types of lasers?
To answer this question, we must first understand where the light energy that makes up laser comes from. The light energy is derived from a medium (for example carbon dioxide, neodymium: yttrium-aluminium-garnet (known as the Nd:Yag). The molecules of this medium release light energy and this light energy is then focused into a small area of high intensity of light. The medium will confer the laser energy its specific wavelength and properties. This explains why there are so many different types of lasers with different wavelengths.

How do lasers work?
Different things in our skin preferentially absorb laser energy of different wavelengths. This is the principle of selective photothermolysis and the basis that laser works on. This is why doctors use a certain laser to treat say, pigmentation, and another laser (of a different wavelength) to treat a different condition like visible blood vessels. These substances that absorb specific wavelengths of laser are called chromophores. Examples are of chromophores are melanin (which makes pigmentation look dark), hemoglobin and water.

Once these chromophores in the skin absorb laser energy, the light energy that makes up the laser gets converted to heat energy that produces changes in the chromophore, such as breaking up pigmentation or stimulating collagen growth. 

The principle of selective photothermolysis allows doctors to precisely target a specific dermatological problem at a specific depth of the skin without affecting surrounding normal tissue.

What are the differences between the various types of lasers?
For lasers like the Q-switch Nd:Yag lasers and fractional lasers, these are derived from different mediums and therefore have their own wavelengths and properties. What makes it more confusing to patients is the variety of laser machines with different names from different companies although the laser used is the same. To simplify matters I will discuss the properties and users of the type of laser used rather than specific laser machines. 

Most lasers in aesthetic dermatology are broadly classified into pigmentation lasers, fractional resurfacing lasers, rejuvenation lasers and ablative lasers. 

Pigmentation lasers
Pigment lasers are selectively absorbed by pigments (i.e. chromophores) and the heat energy from the laser breaks up the pigmentation into smaller fragments for the body to naturally clear these fragments by the lymphatic systems.

Melanin absorbs light at a wide spectrum of wavelengths from 250nm to 1200nm and this implies that lasers of wavelengths that fall within this range can be used to treat pigmentation. The most common laser used to treat pigmentation in Singapore is the Nd:Yag laser which has a wavelength of 1064nm and can target dermal (deep) pigmentation. Most Nd:Yag laser machines consist of a KTP crystal that halves the wavelength of the Nd:Yag laser to 532nm and this allows the laser to target superficial epidermal pigmentation. The longer the wavelength the deeper the laser penetrates through the skin. Some pigmentation types are superficial – like solar lentigos — and some pigmentation types are deeper like Hori’s Naevus, and so the diagnosis of your pigmentation type is the most important factor in determining your treatment outcomes and recommendations. 

For pigmentation and tattoos, the melanin or tattoo pigments are contained within the cells of the skin. These particles are sub-micrometre in size and for these tiny particles within the cells to absorb the laser energy, the laser energy has to be delivered in nanoseconds. For the Nd:Yag laser, this is achieved through a method called quick switching (also called Q-switch) which creates these ultra short bursts of laser energy to allow penetration of the laser energy into the cells. This is why the Nd:Yag laser is also called the Q-switch Nd: Yag laser. Some examples of Q-switch Nd:Yag devices are the Medlite and Tri-beam lasers. 

Similarly, redness from blood vessels in the cases of telangiectasias and blood vessel malformations are treated with the lasers that target hemoglobin, the red protein in red blood cells flowing through these blood vessels. The gold standard for treating these blood vessels is with the pulsed-dye laser. An example of pulsed dye laser is the v-Beam.

Fractional resurfacing lasers
As the name suggests, fractional resurfacing lasers resurface the skin so they are used to treat conditions such as depressed scars, (like acne and chickenpox scars) and sun-damaged skin. One commonly used fractional resurfacing laser is the fractional CO2 laser.

In the 1990s, ablative full resurfacing lasers were the only option for resurfacing the skin. Ablative full resurfacing lasers were very effective but the long downtime and high risk of complications of ablative resurfacing lasers led to these lasers falling out of favour. 

The advent of fractional resurfacing lasers allows the resurfacing benefits of laser while keeping downtime and risk of complications to a minimum. In fractional resurfacing lasers, the laser is delivered in micro beams with islands of sparing of the skin. This creates pockets of surrounding columns where the micro beams of laser have been delivered, known as fractional photothermolysis. These microbeams of laser penetrate the epidermis and dermis and this initiates a natural healing in the skin and collagen formation that accelerates the formation of new healthy tissue for skin regeneration and rejuvenation. Fractional laser allows faster healing as the untreated 'normal' or healthy islands of skin helps to quickly fill in the areas where the microbeams of laser have passed, with new cells.

An example of fractional resurfacing laser is the fractional CO2 laser, which is regarded as the gold standard for treating depressed scars. The chromophore for fractional CO2 laser is water, which is abundant in the epidermis and dermis, allowing the fractional CO2 laser to cause resurfacing of the skin and stimulate collagen growth in depressed acne scars.

Skin rejuvenation by non-ablative resurfacing lasers
Lasers can also achieve all round facial rejuvenation with reduction of signs of ageing such as fine lines and wrinkles, saggy and laxity by targeting the deeper layer of the ski). The hallmark of non-ablative resurfacing lasers is sparing of the epidermis, so there is no injury to the surface layer of the skin, while targeting the dermis to induce collagen formation. The long-pulse lasers like the long-pulse (miliseconds). An example would the long pulse Nd:Yag laser. Usually multiple sessions of non-ablative resurfacing lasers are required to achieve appreciable results compared to fractional lasers for resurfacing of the skin. However, non-ablative resurfacing lasers are a good option for patients who cannot tolerate downtime and more aggressive treatments. 

Full ablative lasers
As mentioned above, full ablative lasers for resurfacing the skin have fallen out of favour because of the long downtime and high risk of complications.

What about Thermage and Ulthera?
Thermage and Ulthera are not lasers. Thermage utilises radiofrequency waves and Ulthera utilises High Intensity Focused Ultrasound (HIFU) to stimulate collagen growth and remodelling for tighter skin, to sharpen face contours and to smoothen fine lines and wrinkles.

Both radiofrequency and HIFU do not treat conditions such as pigmentation, pores, blood vessels and scars. The skin tightening from radiofrequency and HIFU are significantly better than long-pulsed lasers and can be combined with the Q-switch laser as an effective anti-ageing aesthetic treatment.

Why are some lasers painful and incur downtime?
The lasers that incur downtime are typically the resurfacing lasers. This is because these lasers are absorbed by chromophores and the epidermis and dermis (e.g. the chromophore for CO2 laser is water) and this results in photothermolysis in both the epidermis and dermis in order to allow regeneration of new skin and formation of collagen and elastin in order to resurface scars and rejuvenate aged skin. It is this removal of the epidermis and dermis that is considered a form of controlled skin injury that leads to downtime; and this initiates normal wound healing for the resurfacing results.

Compare this to lasers that are less painful and do not incur downtime like the Q-switched Nd:Yag laser, which targets breaks up melanin. There is considerably less 'injury' caused and only the pigments are targeted, without removal of the epidermis and/or the dermis.

What is downtime? Is there anything that I need to avoid during downtime?
Downtime is period of time when the skin is healing from fractional resurfacing lasers. The skin looks redder and swollen and can feel itchy and tender. There may also be scabbing and transient darkening of the skin. These changes are related to increased blood flow and collagen remodelling.

Sun avoidance and the use of appropriate skincare are advised during downtime to avoid complications like hyperpigmentation, acne and milia.

What is the difference between lasers performed by doctors in a clinic versus lasers done in a beauty salon/spa?
In Singapore, lasers are divided into 5 classes (1, 2a, 2b, 3 and 4) in increasing order of their laser hazard. The hazard classifications are defined by the parameters of the laser, which include the power output and emission radiation of the laser.

Class 1 to 3a are considered low power with low risk of complications and are akin to a torch light shining on your skin with no benefits. Class 3b and 4 are considered medium to high power devices with risk of burns and injuries to the eyes. Class 4 laser devices for treatment of skin conditions can only be used by doctors in clinics, and  not by beauty therapists in salons or spas. In other words, medical grade laser devices can only and should only be used by doctors in clinic for safety reasons. Class 3b and 4 laser devices also require a licence from the National Environmental Agency before purchasing and owning these devices. 

Laser beam

Diagnosis and treatment
The treatment of skin conditions is not a one size fits all laser treatment. Determining the diagnosis, such as the type of pigmentation you have, and instituting the right treatment plan with the appropriate skincare and medications will determine the outcome. This is where the doctor's training and experience are very important. A therapist or beautician is likely not going to be able to achieve a diagnosis and proper treatment plan for you.

Laser protocols and efficacy
Skin conditions vary from person from person even though the diagnosis (e.g. acne scars) appears the same. Therefore, tailoring a laser plan for the patient is important and this a complex affair that involves selecting parameter values such as wavelength, fluence, spot size, number of pulses, pulse duration, pulse delay and repetition rate. The person best able to do this properly for you is a skilled and experienced doctor.

Considering the abovementioned considerations — medical grade devices backed by studies, proper medical diagnosis and treatment, the efficacy for lasers performed by trained and experienced doctors compared to a therapist or beautician is very likely to be more effective and not to mention, safer. 

Why do different people get different results? Why is it that my friend had faster clearance of her pigmentation than I did?
Even for the same condition such as pigmentation; there are different types —  for example, sunspotsare superficial versus melasma which involves the deeper part of the skin and has a hormonal component. There are also lifestyle factors such as sun exposure behaviour, use of appropriate skincare and whether other modalities of treatment are also used that will affect the results and how fast results are seen.

Is the stronger or the more frequent the laser treatment the better it is for me?
No and this is a common misconception held by patients. Lasers are performed till the clinical endpoint is reached; this is a reaction that happens to the skin during treatment and indicates therapeutic response. When this therapeutic endpoint is crossed, a risk of complications such as burns, bleeding and hyperpigmentation can arise.

Secondly, lasers treatments performed inappropriately and more frequently than required can cause complications such as hypopigmentation and hyperpigmentation.  

What are the differences between laser and IPL?
Intense pulsed light or IPL for short mimics laser to a certain extent. Lasers consist of a single concentrated beam of light of one wavelength; IPL consists of a broad spectrum of light (i.e. different wavelengths of light make up IPL). When various wavelengths of light are used, different chromophores are targeted. This means that IPL tends to be less selective than lasers and carry a higher risk of complications.

Lasers can also be controlled to focus onto a small spot size to selectively target a small area without affecting surrounding tissue. IPL on the other hand, is less controlled and tends to spread out over a large area like light normally would. Lasers can also travel deeper into the skin to target chromophores in the dermis, but IPL is unable to reach this depth.

IPL is commonly offered in spas and beauty salons because unlike lasers, IPL does not require a license for its use. However, IPL still carries a higher risk of complications and should not be administered by an untrained and inexperienced practitioner.

Do lasers make my skin more sensitive?
In general, lasers do not make the skin more sensitive. For some lasers such as the fractional CO2 laser for resurfacing the skin and acne scars may cause transient skin sensitivity during the recovery period. This resolves within a week. During this period when the skin is recovering, it is important that you use appropriate skincare as discussed with your doctor to prevent inflammation of the skin. 

Do lasers make my skin thinner?
Unlike chemical peels, lasers do not think the skin. In fact, lasers stimulate collagen and elastin growth of the skin to increase skin firmness and thickness!

Find out more about La Clinic here. Read Dr Rachel Ho's blog here