Lin, 2000  Title: Reduction of regrowing hair shaft size
and pigmentation after ruby and diode laser treatment.
Authors: Lin TY, Dierickx CC, Campos VB, Farinelli
WA, Rosenthal J, Anderson RR
Journal: Arch Dermatol Res 2000 Feb-Mar;292(2-3):60-7
PMID: 10749557 ABSTRACT
Affiliated institution: Department
of Dermatology, Massachusetts General Hospital, Harvard Medical
School, Boston 02114, USA.
Laser pulses which selectively damage pigmented hair follicles
are a useful treatment for hypertrichosis. Clinically, regrowing
hairs are often thinner and lighter after treatment. In this study,
hair shaft diameter and optical transmission (700 nm) were measured
before and after ruby (694 nm) and diode (800 nm) laser irradiation.
Hair was collected from 47 and 41 subjects treated with ruby (0.3
ms and 3 ms) and diode (10-20 ms) lasers, respectively. "Responders"
were defined as subjects with significant long-term hair loss
as determined by hair counts at 9 and/or 12 months after treatment.
In ruby laser responders (34/47), regrowing hairs were significantly
both thinner (decreased diameter) and lighter (increased transmission).
In "nonresponders" (13/47), regrowing hairs were lighter,
but not thinner. The regrowing hair shaft absorption coefficient
(as calculated assuming Beer's law) was significantly decreased
by 0.3 ms ruby laser treatment, but was not changed by 3 ms ruby
laser or diode laser treatment. After diode laser treatment, 38
of the 41 subjects were responders and regrowing hairs were both
thinner and lighter. These results show that laser treatments
can affect structural recovery (size of hair), follicular pigmentation
(hair absorption coefficient), or both. Regrowth of thinner hair
(decreased shaft diameter) occurs in conjunction with actual loss
of hair. After long pulses (3 ms ruby; diode), regrowing hair
was thinner and also lighter to an extent related to the decrease
in hair diameter. In contrast, short ruby laser pulses (0.3 ms)
appeared to be capable of inhibiting follicular pigmentation per
se, in addition to affecting the hair diameter. This may account
for the complete regrowth of lighter hair in "nonresponders"
treated with 0.3 ms pulses. Laser-induced reduction in hair diameter
and/or pigmentation are both long-term responses which confer
cosmetic benefits in addition to actual hair loss.
|
|
hair removal
facts
for consumers
