The two laws of laser therapy that we will discuss in this article may sound self-evident. However, very few therapists spend time to think this over.
The first law of phototherapy states that light must be absorbed for any photoreaction to occur.
In a previous article, Laser beam interaction with the skin, we’ve looked at all the different reactions that can occur when a light beam hits the skin. We also established that results can only be expected if absorption of the light occurs.
To make sure that the light actually reach the skin, the skin on the area to be treated must be clean and uncovered. Clothing and other skin dressings will greatly reduce or even totally block light from reaching the skin.
The second law of phototherapy states that whatever the condition, the absorbed energy at target has to be within the therapeutic window.
Let us first define what a therapeutic window is in aesthetic laser therapy. The conditions under which a particular therapy can be given safely and effectively. A therapist will adjust the treatment parameters like; fluence, pulse duration and skin cooling, to meet the conditions for a safe and effective treatment.
Thus, it is not enough for the light just to be absorbed, the correct amount of energy must be transferred for the correct period of time.
Under-treatment occurs when light gets absorbed, but not enough or not long enough. And over-treatment is a result of too much light being absorbed, or enough light being absorbed by a not-intended target molecule. Both these events fall outside the therapeutic window.
