Page 199 - Chapter 3 - Laser/IPL Hair Removal

Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
Catagen and telogen follicles
When treating any body area some of the follicles are bound to
be in either catagen or telogen phase. These will not be adversely affected by photothermal treatments. These follicles will most likely grow between sessions.
Dormant follicles missed completely
We all have dormant follicles in our skin. They will stay dormant until something triggers them into activity. These cannot be damaged by photothermal treatments.
Deeper follicles missed – insufficient fluence
Fluence drops rapidly with depth so deeper follicles need
higher incident fluences to ensure proper cooking. This applies, particularly, to regions such as the under arms and pubic areas where follicles can be as deep as 5 mm.
Insufficient skin surface cooling
This will make the process much more painful and possibly lead to long term skin damage, including scarring, blistering, skin colour changes etc.
Using a good level of cooling will make a big difference. Remember, it’s actually quite difficult to ‘over cool’ the skin’ (unless you are using a very cold method which takes the temperature to well below zero!)
Light-coloured hair
If the hair is too light-coloured it will not have enough melanin in it for a sufficient absorption of light energy. A light-coloured hair is equivalent to a thin hair – both have low quantities of melanin, which is the main light absorber.
Darker skin tones
Darker tones contain more melanin than lighter ones. This melanin steals fluence and induces higher epidermal temperatures, leading to more pain and damage. These tones must be pre-cooled more than lighter tones. However, there is a point where we simply cannot pre-cool sufficiently well. This is a matter of judgement – if you think that you cannot pre-cool enough, then don’t treat them.
Nd:YAG lasers can be used on all skin tones.
Alexandrite lasers deliver a 755nm wavelength which is absorbed three times more readily than the 1064nm from the Nd:YAG laser. This, therefore, generate much more heat in the epidermis, leading to more pain. This laser should not be used on ‘black’ skin tones – it’s just too risky!
________________________________________________________________________ 199 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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