Grossman, 1996  Title: Damage to hair follicles by normal-mode
ruby laser pulses.
Authors: Grossman MC, Dierickx C, Farinelli
W, Flotte T, Anderson RR
Journal: J Am Acad Dermatol 1996 Dec;35(6):889-94
PMID: 8959946, UI: 97119123
Affiliated institution: Wellman Laboratories
of Photomedicine, Harvard Medical School, Massachusetts General
Hospital, USA.
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BACKGROUND: Although many temporary treatments exist
for hirsutism and hypertrichosis, a practical and permanent hair
removal treatment is needed.
OBJECTIVE: Our purpose was to study the use of normal-mode
ruby laser pulses (694 nm, 270 microseconds, 6 mm beam diameter)
for hair follicle destruction by selective photothermolysis.
METHODS: Histologically assessed damage in ex vivo
black-haired dog skin after the use of different laser fluences
was used to design a human study; 13 volunteers with brown or
black hair were exposed to normal-mode ruby laser pulses at fluences
of 30 to 60 J/cm2, delivered to both shaved and wax-epilated skin
sites. An optical delivery device designed to maximize light delivery
to the reticular dermis was used. Hair regrowth was assessed at
1, 3, and 6 months after exposure by counting terminal hairs.
RESULTS: Fluence-dependent selective thermal injury
to follicles was observed histologically. There was a significant
delay in hair growth in all subjects at all laser-treated sites
compared with the unexposed shaven and epilated control sites.
At 6 months, there was significant hair loss only in the areas
shaved before treatment at the highest fluence. At 6 months, four
subjects had less than 50% regrowth, two of whom showed no change
between 3 and 6 months. Transient pigmentary changes were observed;
there was no scarring.
CONCLUSION: Selective photothermolysis of hair follicles
with the normal-mode ruby laser produces a growth delay consistent
with induction of prolonged telogen with apparently permanent
hair removal in some cases.
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