Neauvia Brochure EpilMe - Flipbook - Page 10
MELANIN ABSORPTION
SPECTRUM
Lasers
for hair reduction are
based on the theory of selective
photothermolysis, which implies a
site-specific, thermally mediated injury
of microscopic tissue targets by the
selective absorption of pulses of
radiation by the chromophores1.
The chromophore employed in laser hair reduction is melanin1. Although the absorption of melanin corresponds to
wavelengths from 400 to 1200 nm, the best lasers for hair removal have wavelengths between 600 and 1100 nm, a
range where there is more selective absorption by melanin and the light penetrates relatively deeply into the skin
without dissipation to surrounding tissues2.
PRECISE IMPACT ON HAIR GROWTH
Phases of active hair growth, or anagen, are separated by periods of quiescence, or telogen. Only anagen hairs are
particularly sensitive to physical insults3. The mechanism of action of laser hair removal is reflected in the immediate
histologic changes in the skin, as well as its effects on the hair growth cycle4.
Anagen phase
Treatment
Catagen
CLUB HAIR
Active growth phase
(3-6 years)
Laser treatment
Transition phase (1-2 weeks)
Telogen
SECONDARY
GERM CELLS
DERMAL
PAPILLA
Return to Anagen
HAIR MATRIX FORMING
NEW HAIR
Resting phase (1-2 weeks)
Microscopically
Histologically
Treated follicles display immediate changes of
Most follicles are in the telogen phase 1 month after treatment,
keratinocyte swelling, scattered apoptotic and necrotic
whereas fibrosis with a foreign body giant cell reaction
keratinocytes, and full-thickness necrosis of the follicles
replaces others4. There is a period of alopecia lasting from
depending on the amount of energy absorbed4.
several weeks to a few months until a portion of hair follicles
recover and commence another anagen cycle4.
