Page 248 - Chapter 3 - Laser/IPL Hair Removal

Class III Class IV
Class V
Reduced size, dark DP. A ‘melanin condensate’ formed at the base of the hair shaft.
Coagulation around the hair shaft and bulb immediately after the treatment. Separation of the ORS from the IRS. Regression of the hair shaft indicating a ‘catagen-like’ transition.
Coagulation observed. Vacuolation (steam bubbles) in the DP. Ablation of the hair matrix. Thermal destruction in the ORS.
Chapter 3 – Fundamentals of Laser/IPL Hair Removal 2nd Edition
They applied a diode laser (810nm, 4 to 64 ms, single pulses applied bi-weekly on HFs over five sessions) to volunteers. Their results suggest that both the DP and the ORS are targets for “long lasting” hair reduction. They found 80 to 84% clearance in their volunteers, reducing to 70% four weeks after the last session.
They suggest that the ‘soft’ boundary between HUDs and professional clinic devices is around 10 J/cm2, although they noted that hair reduction was ‘potentially possible’ at all tested fluences.
Their results indicate that a fluence between 6.6 and 10 J/cm2 should induce a Class II or III damage level in most HFs, leading to hair removal on a temporary basis. Class IV and V damage induced by higher fluences would be necessary for permanent hair reduction.
Gan and Graber discuss the application of ‘low fluences’ (5 to 15 J/cm2) from a diode laser onto skin types III to V with ‘less discomfort and fewer adverse effects’ compared with the standard higher fluence protocols. They suggest that lower fluences may induce hair ‘miniaturization’ of coarse, terminal hairs. Rather than inducing the destruction of stem cells, as with higher fluences, they indicate that low fluence application may also trigger altered hair growth due to photomodulation of the stem cells, although this has not yet been proven.
Town et.al. also suggest a similar idea in the modification of the signalling pathways controlling the HF growth cycle. They suggest that, hypothetically, repeated sessions with a low fluence HUD could result in “accumulated damage in the DP or stem cell compartments, ultimately leading to long-term hair reduction”.
Roosen et.al. showed that thermal damage in the matrix and DP induced the ‘catagen-like’ transition after irradiation with an IPL at 9 J/cm2, 15 ms over a wavelength range of 600 – 1100 nm. They observed no thermal damage to the HS, the IRS or the ORS. The low fluence pulses had induced “catagen-like” changes with no observable signs of damage in the stem cell bulge. They suggest that thermal damage to the matrix and DP (due to absorption of light energy by melanin) might be sufficient to interrupt the hair growth cycle, thereby inducing temporary hair reduction.
Thaysen-Petersen et.al. reviewed seven clinical studies with home-use devices, investigating short-term hair reduction following repeated treatment sessions (up to 6 months after the final
________________________________________________________________________ 248 Chapter 3, Ed. 2.0 Laser/IPL Hair Removal
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