INTRODUCTION
The majority of changes we associate with aging are
the results of chronic photodamage and include five
main features: fine lines and wrinkles, enlarged pores,
sagging skin, telangiectasias and dyschromia in the form of
ephelides and solar lentigos.1-4 The pulsed-dye laser (PDL) has
been shown to improve photodamaged skin through a variety
of mechanisms and addresses most of the features of photodamage,
5-11 but not nearly to the same degree. Because the
585-595 nm wavelengths most commonly available from PDLs
are so strongly absorbed by hemoglobin, the telangiectatic and
erythematous components of photoaging are by far the most
susceptible to PDL treatment. Melanin pigment absorbs very
broadly from the ultraviolet end of the solar spectrum, through
the visible and into the infrared spectrum, generally with decreasing
absorption as the wavelength of radiation increases
beyond the ultraviolet end of the spectrum. Absorption in the
585-595 nm range is substantial, and should be quite effective
at treating unwanted pigmentation such as ephelides and solar
lentigos. However, treatment with sufficient fluences to destroy
pigmented lesions at pulse-durations similar to those used with
intense pulsed light sources (IPLs), in the 1.5-3 ms range, results in significant purpura, an unacceptable side-effect. In addition,
hemoglobin absorption of incident laser energy at these
wavelengths prevents much of the incident laser energy entering
the skin from exiting and treating the epidermal pigment a
second time on the way out of the skin (2nd-pass effect).11,12-14
Longer pulse durations of 10 ms or greater do not result in purpura
at most fluences high enough to treat dyschromia, however,
treatment-limiting edema often makes using these longer
pulse-durations to treat pigmentation on the face without
epidermal cooling unpractical. Higher fluences are generally
required to get similar effects removing pigment when using
longer pulse-durations with the PDL.
IPLs are quite effective at treating dyschromia but have some
significant limitations compared to the PDL. Because much of
the incident energy is outside of the absorption peaks of hemoglobin,
treatment of erythema with IPLs is less predictable than
with PDLs and generally less effective, since most of the 595
nm PDL laser energy goes into doing work of heating unwanted
blood vessels, while much of the energy emitted from an IPL
is not taken up significantly by blood vessels. In addition, IPLs
have the disadvantage of delivering large spot sizes and long
