Page 107 - Blog Posts v1

hair grows for much longer times than our eyebrow hair, for example. Otherwise our eyebrows would reach our feet!
How does laser/IPL hair removal work?
Laser/IPL hair removal is based on the theory of ‘selective photothermolysis’ where light is preferentially absorbed by a target (in this case, melanin). By doing this we can effectively concentrate the light energy into the target rather than the surrounding tissues. If we choose an appropriate time in which to deliver this light energy, we can significantly limit the thermal damage to the collagen around the follicles too.
So, we must choose both the wavelength (colour) of our light and its pulsewidth (cooking time) carefully to ensure maximum effectiveness.
However, the melanin in the hair shaft is NOT the real target!! It is merely a conduit. The real targets are the germ, or stem, cells which are found in a region near to the insertion of the arrector pili muscle, which is quite high up the follicle. At this point we should consider the growth phases of hair.
It is known that there are essentially three growth phases of hair:
Anagen
This is the actively growing phase, when the local melanocytes are transferring melanin granules to the follicle – both the hair shaft and the follicle epithelium. During this phase the hair/follicle structure is at its ‘darkest’ with melanin, with the full length of the hair shaft being pigmented. This is very important when considering any light-based treatment.
This phase can last from a few weeks to years (in the scalp).
Mike’s Blog Posts 107