INTRODUCTION
Chronic sun damage results in most of the changes we
associate with an aged appearance.1-4 This can easily be
shown by comparing sun-protected to sun-damaged
skin in the same individual. The five key features of photoaging
are fine lines and wrinkles, enlarged pores, sagging skin,
telangiectasias, and pigmentary alterations. Lasers have been
instrumental for improving photodamaged skin. Numerous
wavelengths have been used to treat the myriad symptoms
of cutaneous photodamage. Lasers that target hemoglobin
have been used to remove sun-induced erythema, while also
stimulating dermal remodeling to improve fine lines and wrinkles
and enlarged pores.5-9 In addition, lasers, and other light
sources that target pigment have been used to remove pigmentary
alterations, while also improving the overall appearance
of treated skin.10-13 To specifically target skin without relying
on melanin pigment or hemoglobin as a target, wavelengths
predominantly absorbed by water have been used. The goldstandard
lasers for improving cutaneous photodamage are the
ultrapulsed carbon dioxide lasers.14-15 These lasers remove the
epidermis and superficial dermis resulting in an open wound
that heals over 1-2 weeks following treatment. Side effects,
including permanent hypo-pigmentation and prolonged erythema
post-treatment lasting three months or more, have limited
the use of these lasers in recent years despite the dramatic
improvement seen following treatment.14-15
In an attempt to derive results similar to laser resurfacing with a
reduced side-effect profile, fractionated lasers were developed
that make tiny wounds in the skin, removing and/or damaging
only a fraction of the photodamaged skin at any one treatment
session, with normal, intact skin in between the zones of damage.
It was theorized that fractionated lasers which treat only a portion
of the skin in a given treatment area would produce similar
results to laser resurfacing utilizing multiple partial treatments to
completely target the skin in a given area. While five 20% treatments
might equate to one 100% treatment when treating an
inanimate object like wood, skin is a living tissue and responds
very differently when healing an open wound versus multiple
small wounds surrounded by zones of normal tissue. Although
fractionated treatments are capable of producing excellent results,
the healing is qualitatively different than that which occurs
following ablative carbon dioxide or Er:YAG laser resurfacing.
Still, the trade off of no or less downtime with more moderate
results is ideal for most patients. In this study, we investigate a
multiplexed 1,440/1,320 nm fractionated laser as it is currently
