March 2009
248
Volume 8 • Issue 3
copyrIght © 2009
original articlEs
Journal of Drugs In Dermatology
Full-face treatments With the 2790-nm
Erbium:Ysgg laser system
E.Victor Ross MD, Michael Swann MD, Seaver Soon MD,
Arash Izadpanah MD, David Barnette MD, Scott Davenport BA
Dermatology Division, Scripps Clinic, San Diego, CA
AbstrAct
Background: Traditional full-face resurfacing has been limited to erbium-doped yttrium aluminium garnet (Er:YAG) and carbon dioxide
(CO2) lasers. These devices offer wavelength-specific advantages and disadvantages.
Methods: Nine patients were enrolled in a pilot study of a resurfacing system using a 2790-nm erbium:yttrium-scandium-galliumgarnet (Er:YSGG) laser system. Two treatments were carried out 1 month apart over the entire face. Test spots were performed
prior to the full-face sessions to determine the optimal fluence for 1-pass laser resurfacing. Biopsies were performed at the time
of treatment and at the final follow-up visit one month after the second treatment. Clinical endpoints included changes in pigment
dyschromias, wrinkles, and skin tone. All outcomes were graded by blinded observers.
Results: Eight patients completed the 2 treatments. Biopsies showed thermal damage extending as deep as 80 µm below the stratum corneum. Reepithelialization was complete within 4 days. No scarring, post inflammatory hyperpigmentation (PIH), or infections
were observed.
Conclusion: A 2790-nm laser can be used for skin rejuvenation with a 4 day recovery window.
IntroductIon
i
n the mid 1990s, carbon dioxide (CO2) laser resurfacing was
typically performed with 1 to 3 passes, and residual thermal
damage (RTD) of 20 µm to 80 µm in the dermis was associated with predictable wrinkle reduction; however, patient
downtime was 10 days to 14 days and, if complicated by infection or hyperpigmentation, could last much longer.1-4 Some patients developed delayed hypopigmentation, particularly those
patients with sun-damaged Fitzpatrick type 2 and 3 skin.
By decreasing the radiant exposures with both CO2 and Er:YAG lasers, mini laser peels evolved where only partial epidermal injury
was achieved, and healing times ranged from 1 to 6 days. These
superficial injuries are associated with low rates of infection, erythema, and most importantly, pigmentation alterations. Recently,
fractional devices have gained popularity.The associated pixilated
injury severity depends on the density of microspots, wavelength,
microbeam radiant exposure, microbeam diameter, and the ratio
of ablation to coagulation for the microcraters. As these procedures treat only a fraction of the skin’s surface (normally in the
range of 10% to 50% surface coverage per treatment session), serial treatments optimize cosmetic improvement.10-15 Compared to
their nonablative counterparts, ablative fractional, devices, particularly with deeper craters and higher densities, tend to achieve
better 1-time cosmetic enhancement, but recovery times can approach traditional deep ablative interventions.
Later, the erbium-doped yttrium aluminium garnet (Er:YAG)
laser became popular as an alternative ablative device. Studies comparing CO2 lasers and Er:YAG lasers showed that for
equivalent results, the Er:YAG laser required similar recovery
times as the CO2 laser.5,6 The Er:YAG laser, when deployed with
pulse widths ranging from 100 µs to 500 µs, shows an ablation
threshold of about 0.5 J/cm2. At radiant exposures above this
threshold, little thermal damage has been observed (usually
The erbium:yttrium-scandium-gallium-garnet (Er:YSGG) laser
less than 20 µm). The lack of thermal damage with the short
has a tissue absorption coefficient roughly 5 times that of CO2
laser and 1/3 that of the Er:YAG laser (Figure 1).16 The erbium
pulsed Er:YAG laser allows for a high rate of water loss from
7-9
YSGG laser, when deployed with a pulse width of 200 µs to 800
the skin surface. This lack of a barrier is associated with immediate oozing and postoperative discomfort. On the other hand,
µs, shows an ablation threshold of about 3 J/cm2. Representing
a hybrid between CO2 and Er:YAG lasers, the authors treated
this same absence of thermal damage permits rapid healing.
patients in this study with 1 pass of the erbium YSGG laser in
With 1 pass, the CO2 laser, at fluence ranges of 4 to 10 J/cm2
and a pulse width of about 1 ms, achieves 50 µm to 80 µm
a protocol designed to achieve wrinkle and dyschromias reducof thermal damage and little true tissue ablation (vaporization).
tion with no more than a 4-day interval for complete reepitheWith multiple passes, the damage extends about 100 µm into
lialization. This paper reports the results of a pilot evaluation of
the dermis, and the wounds heal in about 8 to 14 days (time for
the safety, efficacy and histological effects with this new device.
reepithelialization).
© 2009-Journal of Drugs in Dermatology. All Rights Reserved.
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Journal of Drugs In Dermatology
marCh 2009 • Volume 8 • Issue 3
E. Ross, M. Swann, S. Soon, et al.
Figure 1. Graph showing range
of wavelength-specific absorption
coefficients for water.
Water Absorption by Wavelength
12000
12,500
2940nm Er:YAG
5,000
2790nm YSGG
Absorption (1/cm)
10000
8000
6000
4000
2000
10,600nm CO2
1,000
0
500
2500
4500
6500
8500
10500
Wavelength (nm)
methods
The institutional review board of Scripps Clinic approved the
pilot study. Nine subjects were enrolled, only 8 completed the
study, with skin types 1 through 3, aged 32 to 77 years, with
mild to moderate photodamage. Six of the subjects were females and 2 were males. Informed consent was obtained
from each subject. Patients received 2 full-face treatments, 3
weeks apart, with a 2 790 nm Er:YSGG laser system (Cutera;
Brisbane, Calif). Prior to the full-face sessions, 3 preauricular
test areas (1 X 1 cm2) were irradiated over a range of settings.
The test spots were observed 3 days after treatment and were
used to assess depths of ablation and coagulation as well as
to evaluate the short-term response to treatment. Control and
test area biopsies were taken from each subject immediately
after the test area laser pulses. Although a range of fluences
was applied for the test spots (1.5-3.5 J/cm2) in every patient,
only 1 spot was biopsied per patient immediately after irradiation, where the fluence for the biopsy site was randomly assigned among 8 patients completing the study. Among the
patients’ test spot biopsies, 3 patients were irradiated at 3.5 J/
cm2, 3 patients were irradiated at 2.5 J/cm2, and the remaining 2 patients were irradiated at 1.5 J/cm2. Biopsies were also
performed at the final follow-up visit using the same fluence
as the immediate posttreatment test area for a particular patient. Standardized photographs were taken at each visit with a
Nikon D80 SLR digital camera (Nikon, Tokyo, Japan) equipped
with a flash unit (Twinflash®, Canfield Scientific, Fairfield, NJ).
All photographs were taken in aperture priority mode (f29)
with the same subject to lens distance throughout the study.
Full face treatments were performed at least 30 minutes after
application of a topical lidocaine 5% anesthetic cream. After removal of the topical anesthetic with gauze, an acetone wipe
was performed to ensure that any remaining anesthetic was
removed. Each subject was treated with a single pass extending from the hairline to the jawline. The fluence was chosen
based on the response at the test sites. The highest fluence that
showed reepithelialization after 3 days was used for the fullface treatments. Pulses were applied contiguously using scan
patterns consisting of 6-mm diameter individual laser pulses
with an overlap of 20% (overlap between spots within the scan)
to avoid any untreated areas. The pulse duration was 400 µs.
No wiping was performed after treatment.
Outcome measures included wrinkle reduction, reduction in
pigment inhomogeneities, and improvement in tone and texture. Assessments were carried out by review of photographs
(pretreatment and posttreatment) presented in random order
to a group 3 observers blinded to the order of the photographs.
The raters were asked to make an assessment of which photographs showed the best cosmesis, after which the graders were
asked to score the changes based on percentage of improvement in each category. If the raters chose the pretreatment and
posttreatment photographs in reverse order, then any changes
were reported as negative values. The results were tallied as
means and standard error of mean (SEM) and standard deviation (SD). A paired t test was used for each category to assess
statistical significance. Patients completed a diary during and
after treatment. Also, pain scores were recorded on a visual
analog scale (VAS) during treatment.
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Journal of Drugs In Dermatology
marCh 2009 • Volume 8 • Issue 3
Figure 2. Microscopic appearance
of wounds just after
treatment: a) 1.5 J/
cm2, b) 3.5 J/cm2.
a.
E. Ross, M. Swann, S. Soon, et al.
[median=3]; second treatment: mean=4.6 [median 5]). There
was no relationship between pain and fluence. Postoperatively,
patients reported (from a wound diary) progressive daily healing. By day 1 posttreatment, the mean pain decreased to 1.5. In
patients where less moisture was applied, parchment paper-like
slough was observed between days 2 to 4. With more aggressive application of moisturizer, the daily changes were more
a.
b.
b.
Figure 3. The shortterm response and
long-term results for
a 50-year-old female
who received 2
treatments, 3 weeks
apart, each with
a single pass at a
fluence of 2.1 J/cm2
and pulse duration of
0.4 ms: a) Pretreatment, b) 1 day after
treatment, c) 4 days
after 1st treatment, d)
28 days after second
and final treatment.
results
Eight patients completed the study. One patient dropped out
after the test spots due to unexpected family commitments. Test
spots evaluated 3 days after treatment showed a trend toward
longer reepithelialization times with increasing fluences; however, even with the highest settings, there was almost complete
reepithelialization after 4 days. Biopsies taken from the test area
immediately after irradiation demonstrated a zone of vacuolated and coagulated epidermis. The total depth of these 2 zones
ranged from approximately half of the epidermal thickness at a
fluence of 1.5 J/cm2 to the full-epidermal thickness at 3.5 J/cm2
(Figure 2). Additional histological analysis demonstrated that 3
passes (1 over the other without wiping with at least a 5 second
delay between pulses) at 3.5 J/cm2 resulted in complete epidermal coagulation and residual thermal damage extending 10 microns into the dermis. Based on the test spot results, the mean
fluence for the full face treatments was 2.2 J/cm2.
During treatment, the skin showed an immediate whitening
response with a tendency toward slight browning (char) only
within the overlapping crescent regions within the scan pattern.
This coagulated tissue remained on the skin after treatment.
The treatment time for a full face ranged from 10 to 15 minutes.
Once the petrolatum product was applied, the skin showed a
sunburn–like red appearance. Subjects were instructed to keep
the treated area covered with petrolatum or a similar ointment
until reepithelialization was complete.
c.
d.
Pain was mild during the full-face treatment for most patients
and VAS (1-10) ranged from 2 to 8 (first treatment: mean=3.4
© 2009-Journal of Drugs in Dermatology. All Rights Reserved.
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E. Ross, M. Swann, S. Soon, et al.
Summary data for clinical outcomes
60%
50%
40%
30%
20%
10%
Mean
Mean±SD
0%
pigment
wrinkle
tone
Figure 4. Graph depicting clinical scoring 28 days after final Er:YSGG treatment.
subtle, and sloughing was less obvious. For most subjects,
complete reepithelialization occurred on the third or fourth day
after treatment. All subjects were followed at 1 day, 4 days, and
7 days after the first treatment. All subjects experienced mild to
moderate erythema. Some subjects experienced mild to moderate edema and 1 subject developed contact dermatitis, which
resolved after 3 days of topical corticosteroid use.
Eight patients completed the follow-up visit at 1 month after
the second treatment. All of the subjects rated the discomfort
during treatment as either mild or moderate. Except for 1 subject that developed contact dermatitis, all subjects indicated
that discomfort had resolved by the first or second day after
treatment and that they were comfortable returning to work
between 1 day and 4 days after treatment. All 8 of the subjects
reported improvement in overall skin tone and texture and as
well as an improvement in brown spots (Figure 3 shows a series of photographs in a representative patient). Five subjects
reported improvement in fine lines.
dIscussIon
The water absorption coefficient for the Er:YSGG laser is greater than that of a CO2 laser but less than that of an Er:YAG laser. We speculated that this absorption coefficient would allow
for a) less discomfort and b) finer control of the damage depth
compared to a CO2 laser, while providing greater residual thermal damage than an Er:YAG laser. The histology supports this
contention, as the ratio of the depth of coagulation to ablation
always exceeded unity. In fact true ablation (tissue removal)
at these fluences was not observed, but rather was observed
vacuolization of the upper portions of the epidermis. The stratum corneum was observed in all specimens, indicating that no
gross tissue removal occurred.
With the Er:YSGG laser at these settings, the coagulated layer
acts as a natural dressing and provides patient comfort and
protection in the early healing period.9 The histology demonstrates that this device can evenly coagulate the epidermis using low-fluence settings. Thermal damage can reach the dermis
if high-fluence passes are used. With the present fluence-spot
size configuration, rapid confluent full-face treatments were
optimized. Improvement in brown spots, skin tone and texture,
and fine lines was reported with limited downtime.
The objective clinical results are reported in Figure 4. All
categories showed significant improvement compared to
their pretreatment values (P< .05). Biopsies from the final
follow visits showed thickening of the epidermis (pretreatAlthough the investigators in this study did not directly compare
ment epidermal thickness mean = 42 µm ± 12 µm and postexisting “traditional” Er:YAG and CO2 macrowounding technolotreatment mean = 55 µm ± 15 µm). No changes in number
gies (wounds greater than 1 mm in diameter, to differentiate from
of fibroblasts or vessels per high power field were noted.
© 2009-Journal of Drugs in Dermatology. All Rights Reserved.
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Journal of Drugs In Dermatology
marCh 2009 • Volume 8 • Issue 3
E. Ross, M. Swann, S. Soon, et al.
microwounding fractional techniques), our decade-long laser
resurfacing experience permits the following comments: Compared to CO2 laser, our clinical outcome and microscopic results
are similar to those achieved with lower fluence ranges (ie, 1-2 J/
cm2) at 10 600 nm. Although the very low fluence CO2 laser shows
similar wound healing, intraoperative pain is increased versus
Er:YSGG and Er:YAG counterparts. With similar Er:YAG lasers,
fluences of 2 to 4 J/cm2 typically result in pure ablation of 3 µm/J/
cm2, so that a purely ablative wound approximately 15 µm deep
would be observed with about 15 µm of RTD. Although the total
depths of injury between this type laser and the Er:YSGG are similar, the ratio of coagulation to ablation with the Er:YSGG laser is
associated with less immediate postoperative pain and oozing.
11.
In sum, the advantage of the Er:YSGG laser in this parameter
configuration (2-3.5 J/cm2, 1 pass) is optimizing cosmetic enhancement within the context of inoperative postoperative
pain management, as well as delaying desquamation so that
reepithelialization occurs in concert with sloughing for seamless healing.
15.
dIsclosure
E. Victor Ross is a speaker for Cutera Inc. Dr. Ross has also received an honorarium, research support, and equipment support from Cutera Inc.
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Address for correspondence
E. Victor Ross MD
Scripps Clinic Carmel Valley
3811 Valley Centre Drive, Suite 4B
San Diego, CA 92130
e-mail ............................................ [email protected]
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