Page 74 - Chapter 3 - An Introduction to Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 1st Edition
50 and 60%) of the anagen hairs are killed (in red). But, only the anagen hair follicles are affected leaving most of the follicles untouched. In addition, some of the anagen follicles have not been fully denatured – they will grow back later with finer hairs (usually due to insufficient fluence!).
A short time after the first treatment we can see that the total number of follicles has reduced. However, a few weeks later, some of those follicles have changed phase – this is important! If too short a time is left between treatment sessions, then there may not be much difference in terms of total number of anagen follicles presenting for the next treatment session.
However, some of the follicles which had been in anagen will now be in catagen or telogen. During the second treatment, some of the anagen follicles will be destroyed. A short time after the second treatment we can see the remaining follicles, in various phases...
The ‘trick’ is to treat each area when the maximum number of anagen follicles are present. This can be difficult to determine since we can never know which phase the follicles are in at any one time. However, a good method is to ask your client/patient to return for subsequent treatments when a significant amount of hair is clearly growing. That way, you can be sure of treating many anagen follicles.
Hair treatment intervals – what is the ‘best’ time to leave between sessions?
The follicle germ/stem cells promote anagen hair growth at consistently regular intervals resulting in periods of active growth, followed by inactivity. The duration of these periods depends on the which part of the body is being considered.
Using the model we created above, we wanted to determine the ‘best’ intervals between laser/IPL treatment sessions to generate the best outcomes. Our main criteria was that we wanted to retreat areas when the maximum number of follicles were back in anagen.
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Table 19 - Number of sessions required to kill almost all follicles across the body at an efficiency of 60% (which is fairly typical).
In the real world, nobody can deliver a 100% efficient treatment. So, we can never kill every anagen follicle when we treat. The most realistically achievable efficiency is somewhere between 60 and 80%, in most cases – but many do not appear to achieve this level of efficiency, for various reasons. In Table 19 we show the number of sessions required to kill virtually all follicles across the body when assuming a 60% efficiency. These numbers are very close to what many clinics around the world achieve.
________________________________________________________________________ 74 Chapter 3 Laser/IPL Hair Removal
© The Laser-IPL Guys, 2022
Interval (weeks)
No. of sessions at 60% efficiency
Upper Lip
Chin
Bikini
Legs
Pits
4
7
7
7
9
7
6
8
6
6
6
7
6