Biomedical Engineering Reference
In-Depth Information
perifollicular fi brosis up to 3 weeks after irradiation. Signifi -
cant improvement in infl ammatory acne was observed for
10 weeks after a single treatment and for at least 20 weeks after
four treatments. Both sebum excretion and bacterial porphy-
rin fl uorescence were decreased with sustained reduction of
sebum output for at least 20 weeks of follow-up.
Another study conducted by Itoh and colleagues (212) using
lower fl uence red light (600-700 nm, 17 mW/cm
2
, total dose of
13 J/cm
2
) and 20% topical ALA under occlusion for 4 hours
reported improvement of acne lesions in 13/13 patients treated
with one session. Recurrence of lesions started after 3-6 months,
suggesting that one session might not be enough for sustained
results.
Since then, several open studies report a clinical benefi t of
ALA-PDT in facial acne with application times varying from
0.25 to 4 hours and a variety of light sources, including blue
light, IPL, and PDL. Unfortunately, reports of these studies are
diffi cult to compare because of protocol variations with small
number of patients, short follow-up periods, and variable light
dosimetry. Table 10.6 provides a summary of peer-reviewed
articles on the use of ALA- and MAL-PDT in acne treatment.
sessions of ALA-PDT, 2 weeks apart, using a pulsed light source
(420-950 nm) and a short incubation of 15-30 minutes with
20% ALA. The total reductions of infl ammatory and nonin-
fl ammatory lesion counts were 54.5% and 37.5%, respectively,
after 11 weeks.
Rojanamatin and Choawawanich (218) performed a split-
face study in Thai patients, using IPL (550-700 nm) and 20%
ALA. Fourteen patients received three sessions of IPL on one
side and a combination of short contact (30 minutes incuba-
tion) ALA and IPL on the other side. There were very few adverse
events and they observed a statistically signifi cant improvement
(87.7% vs. 66.8%) in lesion counts 3 months after the last treat-
ment for ALA-PDT and IPL only, respectively. In another split-
face study conducted by Santos and colleagues (219), 20% ALA
was incubated for 3 hours on half of the face, followed by IPL
(560-1200 nm) irradiation to the whole face. Thirteen patients
were treated with two sessions at 2-week interval. At 8 weeks
after initial treatment, 10/13 patients presented greater improve-
ment in the ALA-PDT side compared with the side treated with
IPL alone, however, results were evaluated by a subjective grad-
ing system and lesion counts were not reported.
Taub (220) compared the effi cacies of IPL (680-850 nm),
combination radiofrequency and IPL (580-980 nm), and blue
light (417 nm) for activating ALA-induced PpIX for the treat-
ment of acne vulgaris. All three groups used 30-minute incu-
bation with 20% ALA and received three treatments at 2-week
intervals. They found that IPL-PDT group was superior to
blue light group, although the differences did not reach a sta-
tistical signifi cance. The author attributed these results to IPL's
deeper penetration in the dermis compared with blue light.
Surprisingly, Yeung and colleagues (221) found that MAL-
PDT using IPL and MAL in Asians did not lead to signifi cant
improvement of moderate infl ammatory acne compared with
the control group. It should be noted that a short incubation
time (30 minutes) of 16% MAL cream was used and a relatively
small sample size (23 Chinese patients) was evaluated. They
received four treatment sessions at 3 week intervals in a random-
ized half-facial treatment study with IPL (530-750 nm) alone,
IPL with PDT or as controls. The mean reduction of the infl am-
matory lesion count was 65% in the PDT group, 23% in the IPL
group, and 88% in control group at 12 weeks after last treatment.
Signifi cant reductions of noninfl ammatory lesions were
observed in the MAL-PDT group (38%) and IPL group (43%)
compared with 15% increase in the control group though.
In 2009, a randomized half-facial treatment study by Oh
and colleagues (222) compared two different incubation
times (30 minutes and 3 hours) in 20 Korean patients with
moderate-to-severe acne. Three sessions at 1-month intervals
were performed, with short incubation of 20% ALA plus IPL
(590 nm cutoff fi lter) or long incubation with ALA plus IPL on
one side of the face and IPL alone on the other side. At 12 weeks
after the third session, the reduction of infl ammatory acne
lesions was greater in the long incubation time group than the
short incubation time group or the IPL-alone group, but this
difference was statistically signifi cant only between the long
incubation group and the IPL-only group. The authors believe
that those results could be due to the small subject size or
different number of infl ammatory lesions in each group before
treatment. Moreover, the mean reduction of infl ammatory
acne lesions in the short incubation time was not statistically
PDT with Blue Light
The blue light-PDT studies for acne treatment demonstrated a
range of 25-75% decrease in infl ammatory lesions (213-215)
compared with the lower response (25% reduction) in patients
treated with blue light alone (214). A pilot study conducted by
Taub (213) treated 18 patients with two to four treatments
using short-contact ALA 20% (15-30 minutes) followed by
illumination with blue light or electro-optical synergy or both.
Eleven of these patients had at least 50% improvement and
acne lesions have not recurred in fi ve patients for at least
6 months of follow-up.
Goldman and Boyce (214) compared blue light with and
without 20% ALA in 22 patients with mild-to-moderate acne.
Patients were treated twice with short-contact ALA-PDT/blue
light (15 minutes incubation) at 2 week intervals, whereas
patients in the blue light alone treatment group received two
treatments at 1-week interval. Reductions in papule count from
baseline were 68% in patients treated with ALA-PDT/blue light
versus 40% in the blue light alone group.
A split-face study by Akaraphanth et al. (215) compared
1-hour incubation with 10% ALA blue light PDT versus blue
light treatment alone. Twenty patients received four sessions at
1-week intervals. At 16 weeks after fi rst treatment, the mean
percent reduction of infl ammatory lesions tended to be higher
in the ALA-PDT group: 71.1% versus 56.7% in the blue light
treatment alone; however, it did not reach statistical signifi -
cance. It is possible that the lower concentration of ALA used
in the study and the short incubation time contributed to
those results.
Photodynamic Therapy with Intense Pulsed Light
In 2004, Gold and colleagues (216) treated 15 patients with
moderate to severe infl ammatory acne with 1 hour of 20%
ALA incubation followed by IPL (430-1100 nm at 39 J/cm
2
)
for four treatments per week. The authors reported clinical
improvement in 12/15 patients, with a 71.8% reduction in
infl ammatory lesions after 12 weeks. Subsequently, Gold
and colleagues (217) evaluated 15 patients treated with four
