| FACIAL AESTHETICS | PEER-REVIEW
Figure 6 Skin resurfacing to the lower eyelids in a male patient
requisite for successful, scorch-free skin resurfacing. The CO2
laser achieves the desired results by removing the
outermost layer of the epidermis and some portion of the superficial dermis, and then re-establishing this layer through normal wound healing. Healthy epidermis migrates from adjacent tissue and adnexal structures, and new collagen and elastic tissue are deposited by activated fibroblasts9
. To respond to these requirements and achieve
well-controlled tissue ablation without the risk of scarring or dyspigmentation, it is important to confine ablation to a thin layer (20–50 m m) and deliver enough energy to vaporise the tissue (5 J/cm2
) in a time shorter than the thermal relaxation
time of the skin (1 ms). Two different types of CO2
5–7 J/cm2 laser are promoted for the
purpose of skin resurfacing. The first is a high-power, pulsed CO2
laser that can deliver a treatment fluency of with each sub-millisecond pulse. The second
uses an optomechanical flash scanner connected to a conventional continuous-wave CO2
laser. Later, CO2
resurfacing lasers with short pulse durations (60 microseconds) emerged, which ablate less tissue per pass and leave a narrower zone of thermal necrosis than the original CO2
resurfacing lasers. These systems allow ganglion and travel superiorly in the neck as a plexus
with the internal carotid artery. The fibres take an intracranial course to the cavernous sinus, where they travel through the superior orbital fissure into the orbit via CN branches. The internal and external carotid arteries
contribute to lid arterial supply. The internal carotid arterial supply is from the terminal branches of the ophthalmic artery medially, and the lacrimal artery laterally.
Carbon dioxide lasers The mainstay for skin resurfacing for the past few decades has been the CO2
laser, which has
largely replaced deep phenol peels and mechanical abrasion7
. CO2 lasers emit light at a wavelength of
10 600 nm that is strongly absorbed by water (the primary chromophore for CO2
The CO2 light abundant in the skin).
Conversion of radiant energy to heat at the point of absorption instantly raises the temperature of tissue water to more than 100 C, so that the tissue water evaporates7, 8 laser accurately evaporates the epidermis and
.
dermis, resulting in the reorganisation and strengthening of collagen bundles in addition to epidermal regeneration to rejuvenate the skin. The first CO2
epidermal vaporisation with minimal thermal damage to the papillary dermis. The newer super-pulsed lasers have pulse energies
5–7-times higher than conventional The mainstay for skin
which has largely replaced deep phenol peels and mechanical abrasion.
resurfacing for the past few decades has been the CO2
super-pulsed lasers to maximise tissue vaporisation. This results in pure steam vaporisation with minimal thermal injury diffusing to adjacent tissue. As with other resurfacing modalities such as lasers
chemical peels and dermabrasion, CO2 laser,
completely remove the epidermis and part of the dermis, resulting in wound remodelling with the subsequent formation of new collagen and elastin fibre formation, creating firmer and tighter skin. Studies have shown that the depths of ablation are 20–30 m m and 30–50 m m after one
pass using pulsed and scanning laser technology, respectively10, 11
per pass, which does not increase to more than 150 m m . The residual thermal damage is 20–40 m m
lasers developed used a continuous wave;
however, this technique was not adopted widely owing to thermal damage and the high risk of scarring. The advent of short-pulsed high-energy and scanned CO2
lasers that limit
skin heating revolutionised the resurfacing industry. These are capable of removing layers of photodamaged skin in a precise fashion, leaving only a narrow zone of thermal necrosis. The first laser pass significantly ablates more tissue than subsequent passes, and an ablation plateau is reached at three to four passes, limiting depth to approximately 250 m m. The ability to control the epidermal vaporisation depth with minimal damage to the papillary dermis is a pre-
Figure 7 Periorbital
rejuvenation in a female patient
prime-journal.com | January/February 2013 ❚
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