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FULL ARTICLE
Light emitting diode-red light for reduction of post-surgical
scarring: Results from a dose-ranging, split-face,
randomized controlled trial
Alana Kurtti
1,2
| Julie K. Nguyen
2,3
| Jeremy Weedon
4
| Andrew Mamalis
5
|
Yi Lai
2,3
| Natasha Masub
2,3
| Amaris Geisler
2,3
| Daniel M. Siegel
2,3
|
Jared R. Jagdeo
2,3
*
1
Rutgers Robert Wood Johnson Medical
School, Piscataway, New Jersey
2
Dermatology Service, VA New York
Harbor Healthcare System, Brooklyn,
New York
3
Department of Dermatology, SUNY
Downstate Medical Center, Brooklyn,
New York
4
Office of the SVP for Research, SUNY
Downstate Health Sciences University,
Brooklyn, New York
5
Department of Dermatology, The
Permanente Medical Group, Modesto,
California
*Correspondence
Jared R. Jagdeo, Department of
Dermatology, SUNY Downstate Health
Sciences University, 450 Clarkson Avenue
MSC 46, Brooklyn, NY 11203, USA.
Email: jrjagdeo@gmail.com
Funding information
National Institute of General Medical
Sciences of the National Institutes of
Health, Grant/Award Number:
K23GM117309
Abstract
Scarring has significant esthetic and functional consequences
for patients. A need exists for anti-scarring therapeutics.
Light emitting diode-red light (LED-RL) has been shown to
modulate skin fibrosis. The aim of this study is to evaluate
the safety and efficacy of LED-RL to reduce post-operative
scarring. Cutaneous Understanding of Red-light Efficacy on
Scarring was a randomized, mock-controlled, single-blind,
dose-ranging, split-face phase II clinical trial. Starting 1 week
post-surgery, patients received LED-RL irradiation and
temperature-controlled mock therapy to incision sites at
fluences of 160, 320 or 480 J/cm
2
, triweekly for 3 weeks. Efficacy was assessed
at 1, 3 and 6–12 months. The primary endpoint was difference in scar pliability
between LED-RL-treated and control sites. Secondary outcomes included
Patient and Observer Scar Assessment Scale, collagen and water concentration,
and adverse events. There were no significant differences in scar pliability
between treated and control scars. At certain fluences, treated scars showed
greater improvements in observer rating and scar pliability, reflected by greater
reductions in induration, from baseline to 6 months compared to control scars.
Treatment-site adverse events included blistering (n = 2) and swelling (n = 1),
which were mild and resolved without sequelae. LED-RL phototherapy is safe
in the early postoperative period and may reduce scarring.
Abbreviations: AE, adverse event; CURES, Cutaneous Understanding
of Red-light Efficacy on Scarring; DV, dependent variable; LED, light
emitting diode; LED-RL, light emitting diode-red light; POSAS, Patient
and Observer Scar Assessment Scale; STARS, Safety Trial Assessing
Red-light on Skin.
Received: 26 February 2021 Revised: 19 March 2021 Accepted: 29 March 2021
DOI: 10.1002/jbio.202100073
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any
medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
© 2021 The Authors. Journal of Biophotonics published by Wiley-VCH GmbH.
J. Biophotonics. 2021;e2747. www.biophotonics-journal.org 1of12
https://doi.org/10.1002/jbio.202100073
KEYWORDS
low level light therapy, phototherapy, scarring, wound healing
1|INTRODUCTION
Scar tissue formation is a natural consequence of wound
healing after injury to the skin, and outcomes can range
from faint scarring to aberrant scarring such as hypertro-
phic scars and keloids [1, 2]. Scar prevention is a key con-
sideration in postoperative wound management, as
scarring has significant esthetic and functional conse-
quences for patients [3, 4]. The understanding of the
molecular biology of wound healing is still evolving, and
many strategies exist to prevent and treat scarring [5–8].
Skin fibrosis is an abnormal wound healing response fol-
lowing tissue damage (e.g., burns, surgery, trauma), char-
acterized by excessive fibroblast proliferation and
collagen deposition in the dermis, which may manifest
clinically as scar hypertrophy [9–12]. Skin fibrosis is a sig-
nificant global health problem with an estimated inci-
dence of greater than 100 million persons affected per
year in the developed world [13, 14]. Cutaneous scars
have a profoundly negative impact on patients' quality of
life due to associated pain and pruritus, functional
impairment, cosmetic disfigurement, and psychosocial
distress [13, 15, 16].
There is great research interest and consumer
demand for therapeutic modalities that prevent, reduce,
or remove scars, as evidenced by an estimated $12 billion
annual market for scar treatment in the United States
[17]. Despite the substantial socioeconomic burden asso-
ciated with skin fibrosis, there are few effective and dura-
ble anti-scarring therapeutics available, making scar
treatment a major unmet medical need [18–20]. Further-
more, current scar management strategies may be inva-
sive, cause undesirable side effects, or lack high-level
evidence to support their use [18]. Therefore, it is impor-
tant to research and develop novel approaches to treat
and prevent skin fibrosis.
Visible light (400–700 nm) is ubiquitous in the envi-
ronment and comprises 44% of total solar energy, yet its
cutaneous biologic effects have not been fully elucidated
[21, 22]. Visible light therapy delivered by light emitting
diode (LED) devices is a therapeutic modality of increas-
ing clinical importance in dermatology, as different wave-
lengths can alter skin physiology and provide benefits
such as in wound healing and skin rejuvenation [23–25].
Due to the significant advances in LED technology in
recent years, LED phototherapy has become a valuable
and effective treatment for a wide variety of medical and
esthetic conditions [26]. In 2018, members of the
American Society for Dermatologic Surgery performed
3.49 million procedures using lasers, lights, and energy-
based devices [27]. Furthermore, LED devices are com-
mercially available and have U.S. Food and Drug Admin-
istration (FDA) clearance for various dermatologic
conditions including acne and photoaging [25, 28]. Red
light (630-700 nm) has the deepest tissue penetration
depth of the visible light colors, reaching the entirety of
the dermis where skin fibrosis occurs [24, 29, 30].
Recently published clinical observations indicate that red
light in combination with other modalities, such as pho-
tosensitizers for photodynamic therapy, can decrease skin
fibrosis [31–33].
According to our in vitro data, light emitting diode-
red light (LED-RL) at high fluences (defined as equal to
or greater than 160 J/cm
2
) can exert anti-fibrotic cutane-
ous effects by decreasing the proliferation, collagen pro-
duction, and migration speed of human skin fibroblasts
[34–37]. Prior to our studies on the anti-fibrotic proper-
ties of LED-RL, limited data existed regarding red light
photobiomodulation of dermal fibroblasts. In two
phase I, dose escalation, randomized controlled trials
(Safety Trial Assessing Red-light on Skin [STARS 1 and
STARS 2], n = 115), we evaluated the safety and tolera-
bility of LED-RL administered at fluences up to
640 J/cm
2
on normal skin [38]. Adverse events (AEs)
included treatment-site erythema, hyperpigmentation,
and blistering, all of which were mild and resolved with-
out permanent sequelae [38]. We concluded that LED-RL
is safe up to 480 J/cm
2
and may exert differential cutane-
ous effects depending on race and ethnicity, with darker
skin being more photosensitive [38].
This report describes findings from Cutaneous Under-
standing of Red-light Efficacy on Scarring, a phase II ran-
domized controlled trial designed to evaluate the safety
and efficacy of LED-RL treatment on fresh post-surgical
scars (National Clinical Trials identifier NCT03795116,
registered 20 December 2018).
2|METHODS
2.1 |Study design
This randomized, temperature-matched mock therapy-
controlled, single-blind, dose-ranging, split-face phase II
clinical trial was conducted at SUNY Downstate between
18 April 2019 and 26 October 2020. The study protocol
2of12 KURTTI ET AL.
was approved by an institutional review board and previ-
ously published [39]. The study was performed in accor-
dance with the Declaration of Helsinki and Good Clinical
Practice. All patients provided written informed consent.
Refer to Figure 1 for a schematic of the study design.
2.2 |Patients
Eligible patients were adults (age ≥18 years) who
planned to undergo elective minimal incision facelift sur-
gery with the same surgeon. Patients were screened
according to the inclusion and exclusion criteria
(Table 1). Prior to enrollment, a screening photosensitiv-
ity test was conducted; the patient was exposed to LED-
RL for 20 minutes on the non-dominant upper forearm,
and evaluated 24 hours later for evidence of photosensi-
tivity (e.g., persistent erythema, rash, pain) [40].
2.3 |Treatment
Starting 1 week after surgery (postoperative days 7 to
10), patients received LED-RL irradiation and mock
therapy to the periauricular skin (i.e., sites of the
surgical incisions). The treatment side (right face vs
left face) was randomized, with the untreated side
receiving temperature-matched mock therapy. The
fluence range was based on published reports of LED-
RL maximum recommended starting dose and the
maximum tolerated dose in our phase I studies [28,
31, 32]. Treatment sessions were administered in-
office triweekly for 3 weeks. Patients were randomly
assigned to three treatment groups via block
randomization:
1. Group 1 (Low dose): LED-RL 160 J/cm
2
and mock
phototherapy–30 minutes
2. Group 2 (Medium dose): LED-RL 320 J/cm
2
and mock
phototherapy–60 minutes
3. Group 3 (High dose): LED-RL 480 J/cm
2
and mock
phototherapy–90 minutes
The treatment devices were positioned in close contact
with the skin (within 10 mm), held in place via a custom-
designed headset (Figure 2). Patients were blinded to the
LED-RL treated side, as the treatment areas were outside
of the range of view. For the entire duration of the study,
patients were asked to avoid scar treatments (e.g., topical
medications, intralesional corticosteroids, laser therapy),
FIGURE 1 Schematic of study
design for the Cutaneous
Understanding of Red-light Efficacy
on Scarring (CURES) trial
KURTTI ET AL.3of12
excluding topical agents recommended for routine post-
operative wound care.
2.4 |Treatment devices
The LED-RL source was the Omnilux handheld LED sys-
tem (GlobalMed Technologies, Glen Ellen, CA, USA),
FDA-cleared for the treatment of periorbital rhytides [40,
41]. The LED-RL treatment device emitted visible red
light (633 ± 6 nm) at a power density of 360.2 W/m
2
at
room temperature and a distance of 10 mm from the skin
surface [40, 42]. The mock treatment device simulated
the LED-RL treatment device (i.e., had the same physical
components and thermal output) but did not emit red
light [38]. The use of mock phototherapy controlled for
environmental factors that may affect wound healing,
such as ambient light and temperature [35].
2.5 |Assessments and outcomes
2.5.1 |Efficacy
Assessments were conducted at baseline (i.e., at the first
treatment session) and at follow-up visits at approxi-
mately 1, 3 and 6–12 months post-surgery. While patients
were originally scheduled for a final 6-month follow-up
visit, due to the COVID-19 pandemic, many patients
were required to delay their final visit. The primary end-
point was the difference in quantitative scar pliability
between the LED-RL-treated and control scars. Skin
induration, which reflects scar pliability, was measured
by an indentation instrument, the SkinFibroMeter
(Delfin Technologies, Kuopio, Finland) at the midpoint
of width and length of each scar [43–45].
Secondary outcome measures included the Patient
and Observer Scar Assessment Scale (POSAS) and quan-
titative measurements of collagen and moisture. The
POSASwasperformedbyablindedreviewerinconjunc-
tion with the patient. The two subscales of the POSAS
TABLE 1 Eligibility criteria for the CURES trial
Inclusion criteria Exclusion criteria
•Provision of written
informed consent for all
study procedures
•Stated willingness to
comply with all study
procedures and
availability for the
duration of the study
•Suitable candidate for
elective mini-facelift
surgery
•Pass a screening
photosensitivity test
•Current use of any
photosensitizing
medications
•Light-sensitive conditions
•Diabetes mellitus
•Systemic lupus
erythematosus
•Current tobacco use
•History of bleeding or
coagulation disorder
•Lax skin associated with
genetic disorders
•Open wounds on the face
or neck
•Fibrotic skin disease, pre-
existing scar(s), or other
skin conditions affecting
the periauricular skin
•History of surgery or
procedure involving or
affecting the periauricular
skin within the past
6 months (e.g., prior
facelift, fillers, laser
therapy)
•Tattoos that cover the
proposed treatment sites on
the periauricular skin
•Any other medical
condition(s) that could be
compromised by exposure
to the proposed treatment
Abbreviation: CURES, Cutaneous Understanding of Red-light Efficacy on
Scarring.
FIGURE 2 Custom-designed headset containing an light
emitting diode-red light (LED-RL) treatment device and mock
phototherapy device on opposing sides
4of12 KURTTI ET AL.
each consist of six items rated from 1 to 10, where 1 is
“normal skin”and 10 is the “worst imaginable scar.”
The observer evaluated scar vascularity, pigmentation,
thickness, relief, pliability, and surface area while the
patient assessed pain, itching, color, stiffness, thickness
and irregularity. The Dermo spectroscopy probe
(Connected Physics, Orsay, France) was used to mea-
sure collagen and water concentration in the dermis.
Hydration of keratinocytes has been associated with
reductions in collagen secretion and restoration of the
barrier function of skin, helping reduce scar formation
[46, 47].
2.5.2 |Safety
Treatment sessions were monitored for the occurrence of
safety concerns and AEs, as reported by the patient or
observed by the research team. Patients recorded AEs
during the 3 week treatment period in a home diary.
Common expected post-treatment effects, including
warmth, erythema and edema, were not considered AEs
unless they were prolonged (i.e., lasting more than
24 hours) [38].
2.5.3 |Statistical analysis
This clinical trial was designed to be a preliminary study
to obtain estimates of feasibility and outcome variability.
We estimated that a difference of 15% in scar pliability
would be clinically meaningful, based on the minimum
decrease in fibroblast number in response to LED-RL
irradiation in vitro [34]. A sample size of 30 patients
(with the split-face, intra-individual comparison design)
allowed for an estimate of the variance in scar pliability
change in this population.
SAS version 9.4 statistical package (SAS Institute,
Cary, NC, USA) was used for intention-to-treat analysis
and per-protocol analysis. Each primary outcome was
used as a dependent variable (DV) in mixed linear
models. Fixed factors in each model were treatment
group, whether treated, side of face (left vs right), and
time (three follow-up assessments). Baseline score was
introduced as a scored covariate. Tests of interaction
among fixed factors were conducted, and the utility of
polynomial terms in the baseline DV investigated. DV
scores were power-transformed to remove skew of model
residuals.
3|RESULTS
3.1 |Patient demographics
A total of 30 patients were enrolled and received at least
one treatment session. All patients were female, mostly
non-Hispanic Caucasian (63.3%), and the mean age was
54.1 years (Table 2). Most patients (n = 20, [66.7%]) com-
pleted the study per-protocol (i.e., received all nine treat-
ment sessions). The most common reasons for study
discontinuation were loss to follow-up (n = 2, [6.7%])
and personal reasons (n = 4, [13.3%]).
3.2 |Safety and tolerability
During the entire study period, no serious AEs were
reported. All patients experienced warmth during treat-
ment sessions and reported bilateral post-treatment
TABLE 2 Baseline demographics of patients
Characteristic Total (n = 30)
Group 1 LED-RL
160 J/cm
2
(n = 10)
Group 2 LED-RL
320 J/cm
2
(n = 10)
Group 3 LED-RL
480 J/cm
2
(n = 10)
Age, years 54.1 (7.5) 53.7 (8.2) 52.4 (7.2) 56.3 (7.4)
Sex
Female 30 (100) 30 (100) 30 (100) 30 (100)
Male —— — —
Race and ethnicity
White non-Hispanic 19 (63.3) 5 (50) 6 (60) 8 (80)
White Hispanic 6 (20) 2 (20) 3 (30) 1 (10)
Black or African American 4 (13.3) 2 (20) 1 (0) 1 (10)
Two or more races 1 (3.3) 1 (10) ——
Note: Age is presented as mean (SD). Categorical variables are presented as n (%).
KURTTI ET AL.5of12
erythema, which resolved within 24 hours. Treatment-
site AEs occurred in three patients (10%): two incidences
of localized bulla formation on the LED-RL-treated side
and one incidence of localized facial swelling. There were
no discontinuations due to AEs.
3.3 |Efficacy
3.3.1 |Skin induration (SkinFibroMeter)
No significant differences were detected between treatment
and control in the three groups at 6 months. However, the
scars treated with a medium LED-RL dose (group 2), had
lower induration values at 6 months compared to the con-
trol, reflecting greater scar pliability on the treatment side
(0.02 vs 0.03). In addition, the scars treated with low and
medium LED-RL doses (groups 1 and 2) showed greater
improvements in scar pliability from baseline to 6 months
compared to the control scars. The low dose-treated scars
(group 1) showed a 62.5% decrease in induration from
baseline to 6 months compared to a 40.0% decrease for the
control scars (Figure 3A). The medium dose-treated scars
(group 2) showed a 77.8% decrease in induration from
baseline to 6 months compared to 50.0% decrease for the
control scars (Figure 3B). Detailed primary outcome results
are displayed in Table 3.
3.3.2 |POSAS-patient rating
At 6 months, the high dose-treated scars (group 3) had
better (lower) total PSAS scores compared to the control
scars (13.0 vs 17.0), while the low and medium dose-
treated scars (groups 1 and 2) had worse patient ratings
compared to the control scars (12 vs 10.5 and 23 vs
18, respectively). Both the treated and control scars in all
three groups showed improvement in patient ratings
from baseline to 6 months. Detailed secondary outcome
results are displayed in Table 4.
3.3.3 |POSAS-observer rating
At 6 months, the low and medium dose-treated scars
(groups 1 and 2) had more favorable (lower) total OSAS
scores on the treatment side compared to the control side
(9.0 vs 12.5 and 8.0 vs 14.0, respectively), while the high
dose-treated scars (group 3) had a slightly worse observer
rating on the treatment side compared to the control side
(13.0 vs 12.0). The low and medium dose-treated scars
(groups 1 and 2) showed greater improvements in
observer rating from baseline to 6 months compared to
the control scars. The low dose-treated scars (group 1)
showed a 45.5% improvement from baseline to 6 months
compared to 24.2% for the control scars (Figure 4A). The
medium dose-treated scars (group 2) showed a 57.9%
improvement from baseline to 6 months compared to no
improvement for the control scars (Figure 4B). Refer to
Figure 5 for comparative clinical photos.
3.3.4 |Collagen
Both the treatment and control sides of all three groups
showed increases in collagen from baseline to 6 months,
as expected in wound healing. The medium and high
dose-treated scars (groups 2 and 3) had lower collagen
compared to the control scars at 6 months (60.0 vs 61.0
and 56.7 and 59.3, respectively), a favorable outcome for
FIGURE 3 The low and medium dose-treated scars in (groups
1 and 2) showed greater improvements in scar pliability compared
to the control scars. A, In group 1 (low dose), the treated scars
showed a 62.5% decrease in induration from baseline to 6 months
compared to a 40.0% decrease for the control scars. B, In group
2 (medium dose), the treated scars showed a 77.8% decrease in
induration from baseline to 6 months compared to a 50.0% decrease
for the control scars
6of12 KURTTI ET AL.
the treatment side as excess collagen in scar tissue is asso-
ciated with worse healing.
3.3.5 |Moisture
At 6 months, there were negligible differences in water
concentration between treatment and control in all three
groups.
3.3.6 |Patient satisfaction
70.8% of patients reported they are likely or very likely to
recommend the LED-RL treatment to a friend. 62.5% of
patients reported they are likely or very likely to use this
treatment again after a procedure that may produce
a scar.
4|DISCUSSION
To our knowledge, no clinical trials have evaluated the
safety and efficacy of red light for the treatment or pre-
vention of cutaneous scarring. As in vitro data show that
LED-RL can attenuate profibrotic cellular processes that
contribute to skin fibrosis, LED-RL is a promising strat-
egy to minimize scar formation after surgery [34, 35]. In
this study, LED-RL phototherapy was initiated within
1 week post-surgery, coinciding with the early prolifera-
tion phase of wound healing, to help answer important
questions about the impact of intervention time on final
scar outcomes [48–50]. While no statistically significant
difference in primary outcome between treatment and
control were detected, LED-RL therapy demonstrated
improvements in multiple endpoints. The low and
medium dose-treated scars (groups 1 and 2) showed
greater improvements in scar pliability compared to the
control as demonstrated by the larger reductions in skin
induration over the study period. In addition, lower col-
lagen levels (groups 2 and 3) were measured on the
treated side at 6 months. Greater improvements in
observer ratings on the low and medium dose-treated
scars (groups 1 and 2) compared to the control were also
noted. Interestingly, the 6-month observer and patient
ratings favored opposite sides for each of the three treat-
ment groups. This discordance highlights that scar out-
comes are subject to interpretation and what one person
perceivestobeimproved,maynotbethesamefor
others.
A dose-ranging study design was implemented as
the safety of LED-RL phototherapy in a facelift scar
model may differ from the safety in normal skin. For
example, LED-RL fluences determined to be safe in
normal forearm skin (the treatment site in STARS
1 and STARS 2) may have different effects on the face,
as physiological properties of skin vary depending on
anatomic location [51, 52]. Thus, the maximum toler-
ated dose established in our phase I studies served as
the upper limit of treatment dose in this study. We
now demonstrated that LED-RL therapy can be safely
used on fresh surgical wounds on facial skin. No seri-
ous AEs were reported, and the few non-serious AEs
reported were temporary and resolved without sequelae.
Patients expressed high satisfaction with the treatment
as the majority reported that they are likely or very
likely to use the treatment again and recommend the
treatment to a friend.
TABLE 3 Results of primary endpoint
Treatment group
Treatment or
control side Time point Median
Percent change
([baseline–6 month]/baseline)
SkinFibroMeter (N) Group 1 Treatment Baseline 0.08 #62.5
6 month 0.03
Control Baseline 0.05 #40.0
6 month 0.03
Group 2 Treatment Baseline 0.09 #77.8
6 month 0.02
Control Baseline 0.06 #50.0
6 month 0.03
Group 3 Treatment Baseline 0.06 #50.0
6 month 0.03
Control Baseline 0.07 #71.4
6 month 0.02
KURTTI ET AL.7of12
TABLE 4 Results of secondary endpoints
Treatment
group
Treatment
or control
Time
point Median
Percent change
([baseline–6 month]/
baseline)
POSAS- Patient Rating Group 1 Treatment Baseline 36.0 #66.7
6 month 12.0
Control Baseline 37.0 #71.6
6 month 10.5
Group 2 Treatment Baseline 32.0 #28.1
6 month 23.0
Control Baseline 30.5 #41.0
6 month 18.0
Group 3 Treatment Baseline 26.5 #50.9
6 month 13.0
Control Baseline 28.5 #40.4
6 month 17.0
POSAS- Observer
Rating
Group 1 Treatment Baseline 16.5 #45.5
6 month 9.0
Control Baseline 16.5 #24.2
6 month 12.5
Group 2 Treatment Baseline 19.0 #57.9
6 month 8.0
Control Baseline 14.0 0
6 month 14.0
Group 3 Treatment Baseline 18.0 #27.8
6 month 13.0
Control Baseline 16.5 #27.3
6 month 12.0
Collagen Group 1 Treatment Baseline 48.7 "17.0
6 month 57.0
Control Baseline 52.0 "8.7
6 month 56.5
Group 2 Treatment Baseline 51.0 "17.6
6 month 60.0
Control Baseline 50.5 "20.8
6 month 61.0
Group 3 Treatment Baseline 47.7 "18.9
6 month 56.7
Control Baseline 52.5 "13.0
6 month 59.3
Moisture (%) Group 1 Treatment Baseline 63.0 #0.8
6 month 62.5
Control Baseline 65.3 #6.3
6 month 61.2
Group 2 Treatment Baseline 60.7 "4.9
8of12 KURTTI ET AL.
This study's methodology offered several advantages
compared to other clinical trials that evaluate scar man-
agement strategies. The split-face study design allowed
each patient to serve as their own control, such that com-
parisons of clinical efficacy between treated and control
scars are within-patient (i.e., intra-individual). Therefore,
any measured changes in scar characteristics can be
attributed to the treatment, eliminating the confounding
factor of inter-individual differences in wound healing. It
is important to note that in the prospective evaluation of
scar reduction therapy, it is assumed that if left
untreated, the bilateral facelift incisions would heal with
identical scars. Furthermore, the treated side of the face
was randomized to account for possible differences in
skin quality (e.g., asymmetry of sun exposure in automo-
bile drivers) [53]. Lastly, this study employed both objec-
tive and subjective outcome measures. The use of
quantitative measurements allowed detection of mechan-
ical skin properties changes not easily appreciated with
subjective assessment of skin appearance.
This study had several limitations. There was a bias in
age toward middle-aged and elderly individuals, as these
are the typical facelift patients [54, 55]. Increased age is
associated with reduced collagen turnover due to a
decrease in fibroblast collagen synthesis, which may affect
the penetration and cutaneous effects of LED-RL [56, 57].
Furthermore, since cell turnover is a major contributor to
the development of scar tissue in a healing wound, elderly
individuals tend to have better outcomes for scar cosmesis
and are less susceptible to pathologic scarring [58–61]. The
majority of observer ratings reflected very subtle scarring,
with over 70% of the scar characteristics (vascularity, pig-
mentation, etc.) rated between 1 and 3 out of 10. Because
the majority of patients had minimal scarring, it was diffi-
cult to detect differences between the treated and control
scars. A greater number of treatment sessions over
TABLE 4 (Continued)
Treatment
group
Treatment
or control
Time
point Median
Percent change
([baseline–6 month]/
baseline)
6 month 63.7
Control Baseline 62.7 "0.5
6 month 63.0
Group 3 Treatment Baseline 63.2 #1.9
6 month 62.0
Control Baseline 66.2 #3.3
6 month 64.0
FIGURE 4 The low and medium dose-treated scars in (groups
1 and 2) showed greater improvements in observer rating from
baseline to 6 months compared to the control scars. A, In Group
1 (low dose), the treated scars showed a 45.5% improvement from
baseline to 6 months compared to 24.2% for the control scar. B, In
Group 2 (medium dose), the treated scars showed a 57.9%
improvement from baseline to 6 months compared to no
improvement for the control scars
KURTTI ET AL.9of12
additional weeks to months may have also correlated with
greater differences between treated and control scars.
Additionally, the thermal output of the mock device may
have improved the appearance of the control scars. Lastly,
while patients were blinded to the treatment side, they
commonly reported greater sensation of warmth during
treatment and greater degree of post-treatment erythema
on the LED-RL-treated side.
Given the complexity of wound healing and the
many potential confounding variables, it is challenging
to devise and conduct robust clinical trials evaluating
scar therapies. Studies are often limited by small sam-
ple sizes, subjective assessment tools, and well-healing
scars that make it difficult to detect differences
between treated and control scars. For instance, sev-
eral systematic reviews have concluded that silicone
gel significantly improves scar outcomes. However, in
a randomized double-blind placebo-controlled clinical
trial including 12 patients, no statistically significant
difference between scars treated with silicone gel and
scars treated with a placebo after direct brow lift sur-
gery were detected [62]. The researchers believed that
because brow lift scars tend to heal well and not form
hypertrophic scars, it was difficult to detect differences
between the treated and control scars. Better scar out-
comes, albeit non-significantly, were observed on the
treated side and perhaps the silicone gel would have
had greater effects on hypertrophy-prone scars. Our
study faced similar challenges as the facelift scars were
subtleandinananatomiclocationnotpronetopatho-
logic scarring. Thus, the improvements observed on
the LED-RL treated side, while not statistically signifi-
cant compared to the control, should not be
overlooked.
With LED-RL therapy showing great promise, the
modality warrants further evaluation in a high-powered
study with a larger sample size. Because all doses dis-
played excellent tolerability and conferred improvements
in multiple endpoints, all three doses merit further
assessment in a phase III study. To mimic real-world
practice, home-use LED-RL devices should be evaluated.
Lastly, the effects of LED-RL therapy on hypertrophy-
prone scars should also be investigated.
5|CONCLUSION
There is a large unmet need for innovative therapeutic
strategies to prevent cutaneous scarring after surgery.
Despite the substantial healthcare burden of skin fibrosis,
there is no “gold standard”or universally effective scar
therapy, and current treatment options have limited clin-
ical efficacy and durability [8, 18, 63]. This study demon-
strates that LED-RL phototherapy can be safely used in
the early postoperative period on facial skin and may
reduce post-surgical scarring, as shown by improved scar
cosmesis of the treated sites. Future studies may extend
beyond scar prevention and investigate the use of LED-
RL to treat existing scars.
CONFLICTS OF INTEREST
Dr. Jared Jagdeo and Dr. Daniel Siegel are on the Scien-
tific Advisory Board for Global Med Tech. Dr. Jared
Jagdeo also serves as a consultant for Global Med Tech.
The other authors have no conflict of interests to declare.
AUTHOR CONTRIBUTIONS
Alana Kurtti, BS and Julie K. Nguyen, MD should be con-
sidered joint first author.
DATA AVAILABILITY STATEMENT
The data that support the findings of this study are avail-
able from the corresponding author upon reasonable
request.
ORCID
Daniel M. Siegel https://orcid.org/0000-0002-3918-9483
Jared R. Jagdeo https://orcid.org/0000-0002-7619-7650
FIGURE 5 Control scar
compared to low dose light emitting
diode-red light (LED-RL)-treated
scar (group 1) at 6-month visit
10 of 12 KURTTI ET AL.
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How to cite this article: Kurtti A, Nguyen JK,
Weedon J, et al. Light emitting diode-red light for
reduction of post-surgical scarring: Results from a
dose-ranging, split-face, randomized controlled
trial. J. Biophotonics. 2021;e2747. https://doi.org/
10.1002/jbio.202100073
12 of 12 KURTTI ET AL.