Page 39 - Chapter 3 - Fundamentals of Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
treatments. This not the case! Of course, any therapist that provides IPL/laser treatments must possess basic knowledge in dermatology and the physiological properties of the human skin but without deeper understanding of physical process they will fail to provide safe and efficient treatments. Every year there are several thousands of reported cases with severe and many times permanent side effect after IPL/laser treatments. The fundamental problem is the therapists’ lack of knowledge or understanding of the physics behind light-based skin treatments.
The objective of this book chapter is basically to provide comprehensive guideline how to accomplish safe and effective light-based skin treatments.
The Fundamental Principles of Light-based Hair Removal Treatments
The fundamental principle behind the majority of all light-based skin treatments is simply to transfer the energy confined in a light pulse into heat in specific tissue structures of the skin. We cover this in detail in Chapter 1 – please read that chapter for more information. The process that converts the light energy into heat in an object is called absorption. Light is a so-called electromagnetic wave that travels through empty space without losing any energy at all until it hits an object. When a light wave interferes with an object some or all of the wave energy is transferred over to the objects atoms which leads to a temperature increase in the absorbing object.
By heating up and coagulating (requires a peak temperature of approximately 70-75oC) the specific tissue cells that are related to certain skin structures such as hair growth, benign pigmentations and vascular lesion, it is possible to permanently eradicate these types of tissue disfigurements.
The treatment principle described above is known as "Selective Photothermolysis - SPT" in the scientific community. This procedure may sound pretty simple, but it is not! Though it is very easy to "bulk" heat the skin by exposing it to unspecific light, it is rather difficult to make the heating process selective to just the target cells, for each specific skin structure. Severe side effects such as scarring may occur if other than the specific skin structures are permanently damaged.
Side effects after IPL treatments due to improper device settings. In this case, it appears that there was insufficient skin surface cooling during, and after, the treatment, leading to excessive thermal damage in the dermis.
It is very easy to damage the skin using modern lasers and IPLs. This can be significantly reduced with proper understanding and training.
Figure 9 - A badly done IPL treatment due to incorrect
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choice of settings and lack of cooling