More is always better, right? Not always, when it comes to laser therapy. Among scientists, in journals, on the internet, and among the practitioners who use laser therapy, it is a continuous discussion whether you achieve better results when you use more powerful lasers.

Manufacturers of Class 4 lasers claim that you do while those who offer Class 3B lasers say the opposite. Let us examine some of the facts regarding the differences in the treatment with these two types of lasers.

Laser classes
Lasers for medical use are divided into different classes: 1 (up to 1 mW/cm2), 2 (up to 2 mW/cm2), 3R (up to 5 mW/cm2), 3B (up to 500 mW/cm2), and Class 4. In order to treat underlying areas (around bones and underlying muscle groups), you need a certain amount of energy, which naturally excludes Classes 1, 2, and 3R. as mentioned, Class 3B lasers deliver up to 500 mW per cm2, while everything above 500 mW is considered Class 4.

Lasers in Class 4 are meant for burning, cutting, or evaporative purposes – in the medical field, this usually means surgery, removal of tissue, eye corrections etc. Significantly large amounts of energy within a very limited area make this possible. It is the intensity that is measured in mW/cm2. High intensity for a longer period of time will result in rapid heating of the tissue and will in some cases create a risk of burning and in other cases over dosage. You will see this if you hold a Class 4 laser still for just a moment during the treatment.

If you wish to use Class 4 lasers, which are often 10-12 W, for therapeutic purposes and treat underlying areas, you can use a few different techniques:

  • Spreading the laser light over a large area
  • Adjusting the duty cycle where the effect is delivered in pulses, and the duty cycle indicates the length of time the laser is on
  • Sweeping movements over the treatment area
  • Spreading the laser light

It is possible to spread the laser light over a large area either via a focusing lens or by creating a larger distance from the laser to the treatment area so that a larger amount of the light is reflected away from the skin.

Duty cycle
If the 10-12 W is the peak output instead of the average output, the duty cycle can be adjusted, i.e. having the laser on for shorter amounts of time so that the tissue has time to cool down before the next impact.

You can treat an area with sweeping movements, i.e. not holding the laser still on the skin during the treatment. With this method, you ensure that you are not applying too much energy per cm2 per unit of time – it is similar to adjusting the duty cycle.

Instead of modified equipment and usage, you can choose to follow the recommendations by WALT (World Association for Laser Therapy) and use a Class 3B laser.

Recommendations by WALT
On their website, WALT has published the following recommendations regarding the dosage:

“Recommended treatment doses for Low Level Laser Therapy: Laser class 3 B, 780 – 860nm GaAlAs Lasers. Continuous or pulsed, mean output: 5 – 500mW. Irradiation times should range between 20 and 300 seconds”

WALT is also the source for the dosage overview in our article on over dosage of laser therapy.

In conclusion, a Class 4 laser can only be used for therapeutic purposes if it is modified or used in such a way that it in essence behaves like a Class 3B laser. Taking into account the fact that Class 4 lasers are often significantly more expensive than Class 3B lasers, it is important to consider what you wish to use your laser for before investing in one.

PowerMedic is, of course, a member of WALT and follows their official recommendations. We offer a 500 mW laser (the PowerLaser 500), a 1500 mW laser (the PowerLaser 1500), as well as an 18,000 mW laser (the GigaLaser), which are all Class 3B.

Keep in mind that the 1500 mW (1.5 W) and the 18,000 mW (18 W) lasers are also Class 3B because they consist of several Class 3B laser diodes, which distribute the energy over a large area. In other words, they deliver the same amount of energy but in a way that minimizes the risk of over dosage and burning.