My name is Stuart Mohr and I am Cutera's Technical Marketing Manager.  I hold degrees in Biomedical Engineering and Electrical Engineering as well as an MBA.  In addition to scholastic credentials, I designed aesthetic laser systems and other laser based technology devices for 10 years prior to going into marketing.

In this blog, I intend to describe technical and biologic descriptions behind many of our products from Pearl to Laser Genesis to laser hair removal and everything in-between.  I also hope to serve as a resource for anyone that has questions regarding Cutera products or aesthetic systems in general.

Now on to the fun stuff...

The goal during any Laser Genesis procedure is to methodically move the laser across a region of the face (typically ¼ to 1/8th of the face at a time) creating a localized zone of heated tissue with vasodilation.  This is visible as blushing or reddening in the area and should be maintained for a period of time.  Additionally, the patient will notice the increase in tissue temperature and the greater efficacy of each pulse.  By the end of treating any region, the patient should definitely feel the treatment.  The procedure does not require any topical anesthetic or other numbing agents meaning that it is not a painful procedure, but if the patient does not experience some discomfort toward the end of treating a region, the results may less than desired.  Once the treated region is sufficient treated (treat to erythema and vasodilation - typically ~2000 pulses), move to the next region.

To achieve proper fluence delivery, the handpiece should remain within about 1cm of the surface of the skin (about the width of your index finger).  Further away leads to beam degradation and can affect treatment.

Laser Genesis is a very deliberate procedure and should be administered in a methodical manner to achieve optimum results on wrinkles, texture, pore size, and diffuse vascular redness (blush or rosacea).  The treatment depends on both the fluence / pulse duration settings and bulk heating, which can only be obtained by focusing on regions of the face delivering uniform energy across the entire area. 

Treatments are extremely safe on all skin types, but to ensure optimal safety, always move the handpiece to prevent delivery of multiple sequential pulses to the same location.  Allow at least 1-2 seconds after delivering a pulse in any location before hitting that same location again.

Laser Genesis works through two parallel actions to stimulate collagen, improve texture and pore size, reduce wrinkles, and improve redness and fine facial veins—direct absorption and bulk heating.  The first part (direct absorption) requires the use of 0.3ms (or 300 us) pulses.  As described in my blog about pulse duration, short pulses target small objects. 

The target for Laser Genesis procedures is the microvasculature in the papillary dermis.  The laser’s 0.3 ms pulse durations enable Laser Genesis to target these vessels while completely sparing the epidermis.  This enables extremely safe treatments at high rep-rates on all skin types.  Each individual pulse specifically heats up this vasculature closing the larger microvasculature that leads to the appearance of blush.  These treated vessels are then cleared away by the body and evoke a healing response with collagen stimulation.

The second mechanism of action occurs through repetitive pulsing.  The laser operates using a 5 mm spot size pulsing at 10 Hz.  This creates bulk heating in each treatment area leading vasodilation and an influx of blood and healing factors.  Vasodilation also increases the amount of target (blood) in the vessels improving the efficacy of each individual pulse.  In addition to the healing mechanism stimulated by treating the microvasculature, extended bulk tissue elevation also leads to collagen stimulation. 

Achieving optimal results with Laser Genesis is easy, and the device is exceptionally safe on all skin types.  Focusing on the mechanism of action, and treating to achieve these biologic responses will optimize results. 

Any devices that claim to have the ability to “mimic” Laser Genesis, must meet all the requirements of wavelength, pulse duration, fluence, spot size and rep-rate.  If pulse duration or fluence is compromised, the laser does not have sufficient energy to treat the microvasculature.  Smaller spot sizes mean less area is treated per pulse, so less heat is applied to the skin per unit time meaning that bulk heating is compromised.  A change from a 5mm spot size to a 3mm spot size reduces bulk heating by almost 3X even when using the same rep-rates.  If the rep-rate is reduced, the laser does not fire as many pulses per unit of time, therefore reducing the heat delivered to the skin compromising the effect created by bulk heating.

Pulse duration is one of the most significant laser parameters to understand. Proper pulse duration is key to a safe, consistent and effective laser hair removal or vascular treatment. For this reason, it is typically the first parameter set by practitioners. Vein treatments include facial veins, leg veins and an occasional varicose vein treatment--although varicose veins are part of a larger medical condition not treated by a non-invasive aesthetic laser system.

Pulse duration determines the volume of tissue treated by the laser. Long pulse durations treat large volumes, short pulse durations treat small volumes. As an analogy, imagine a hot iron. A person can tap the surface of a hot iron that is several hundred degrees and not feel pain or get a blister. The reason is only the most superficial cells heated up during the time their finger contacted the iron. The heat did not have time to spread deeper into the finger. Conversely, it's extremely difficult to hold a hot cup of coffee even though it's far less hot than the iron. The difference is contact time. The cup is in contact for a long time so heat has time to conduct into the finger. Another analogy that compares to laser treatments is a pot full of hot soup. The soup stays hot in the pot for a long time, but if it's poured into 10 separate bowls, the bowls of soup cool down rapidly. This is because small objects give away heat to their surroundings more rapidly than large objects.

These same concepts are used when performing a laser vein treatment or laser hair removal treatment with an aesthetic laser system. The goal of every treatment is to heat the target you want to treat, but do as little collateral damage to surrounding tissue as possible. Large vessels (like leg veins) are like a pot of soup. They heat up slowly, and also don't give away their heat to their surroundings as well as small veins. This means long pulse durations will heat the vein, but still not heat surrounding tissue. In contrast, small veins, like facial veins, are very small and give away heat to their surrounding tissue quickly. This means energy must be applied in a short time--faster than they can give away their heat. If the pulse duration is too long, some of the energy (heat) ideally meant to treat the vein is lost into surrounding tissue heating the surrounding tissue, but not the vein. So, if the pulse duration is too long, more fluence (power) is required to achieve a clinical endpoint, but some power was wasted in surrounding tissue increasing the risk of complications. If the pulse duration is too long, it becomes impossible to treat the target regardless of the amount of fluence.

Using the correct pulse duration results in the most consistent outcomes with the lowest risk of complication. This allows the lowest amount of fluence to have the greatest impact on the target with the greatest degree of protection to the epidermis. In a nutshell, every treatment wants to use a pulse duration shorter than the time it takes for the target (hair or vein) to give away heat (thermal relaxation time) and longer than the time required for the epidermis to give away heat. Pulse durations longer than 5-10 ms provide epidermal safety by the same principal that prevents a long pulse duration from efficiently treating a small vein. The longer the pulse duration, the safer it is to the epidermis, but if it's too long, it will cease to be effective on the target.

So, in summary, how does someone select the correct pulse duration? Small targets require short pulse durations, large targets respond to long pulse durations. Longer pulse durations maximize epidermal safety. The following are approximate times to help select the correct pulse duration. If the duration is within about 5-10 ms of the ideal pulse duration, the treatment will achieve maximum efficacy and safety with minimum fluence. Remember, cooling is also a critical factor effecting epidermal protection and is also required for safe treatments.

Hair Treatment:

• Fine = 5-20 ms
• Medium = 15-30 ms
• Coarse = 25-50 ms
• Very coarse = 40-80 ms

Vein Treatment (size of vein is measured diameter):

• Typical pulse durations range from 10ms to 100ms for small high pressure telangiectasias to large low flow leg veins.

How does Pearl provide immediate results in one treatment while a Fraxel Laser Treatment typically requires 3 treatments to start seeing results and 5+ treatments to complete? The answer is in the method of delivery. Fractional laser devices only treat a small fraction of the skin with each treatment.  This means even after 3 treatments, only 50% of the skin is actually treated.  Pearl safely and consistently treats both the entire thickness and surface area of the epidermis in one treatment.  Treating the entire epidermis removes pigmented lesions, improves texture, and reduces fine lines and wrinkles - the primary signs of mild to moderate photo aging.

Pearl's wavelength (2790 nm YSGG) is the key that enables it to safely treat the entire epidermis.  This wavelength enables the laser to penetrate through the entire epidermis in a single treatment with the right balance of thermal stimulation.  During delivery, the top 1/3 of the epidermis is immediately removed and the remaining 2/3 is coagulated - meaning 100% of the epidermis is treated.  The controlled depth of heating and coagulation provided by the wavelength provides two additional benefits.  First, it provides a natural protective layer on the skin preventing any bleeding or oozing post treatment. Second, it stimulates collagen growth in the papillary dermis beneath the D/E junction. The coagulated tissue peels off after 3-4 days, unveiling a new completely re-epithelialized epidermis void of many of the signs of mild to moderate photo aging. 

This fresh epidermis is new from the D/E junction up.  This means pigmented lesions stemming from the basal cells at the bottom of the epidermis are replaced with new normal cells.  Pearl's treatment of the entire epidermis, in both coverage and thickness, provides better results on pigment in just one session than multiple IPL treatments.  Further, the body's natural response to laser treatments to the D/E junction is to stimulate new fibroblast growth.  New fibroblast activity results in collagen stimulation helping to eliminate fine lines and wrinkles.  This process occurs more gradually meaning results from a single Pearl treatment continue to improve for as much as 6 to 9 months.

Pearl's depth and three mechanisms of action (immediate ablation, immediate coagulation, and stimulation in the upper dermis) are misunderstood by many people.  Pearl provides immediate visible results in mild to moderate photo damage in just 1 treatment by utilizing these three mechanisms of action while treating the entire surface area of the face.  Further, because of the laser's controlled water absorption, treatments are safe, reproducible and consistent from person to person, removing the guess work.