Presidential Greeting - American Society for Laser Medicine and ...

educe central TM endothelial cell damage. The greater number of
surviving cells could be stimulated to secrete certain cytokines
that increase trabecular meshwork fluid permeability, resulting
in greater intraocular pressure reduction.
#12
OPTIMAL WAVELENGTH SELECTION FOR LASH
TREATMENT OF SKIN PHOTOTYPES I TO VI
Alain Cornil, Sylvain Giraud, Sonia Saai,
Cécile Philandrianos, Guy Magalon
Ekkyo Aix-en-Provence, France; APHM, Hopital Nord, Marseille,
France
Background: Previous studies have demonstrated the efficacy of
laser assisted skin healing (LASH) treatment using a 810 nm
diode laser for improving scars following surgical intervention.
However this new modality was limited to phototypes I to IV, due
to high absorption of melanin at this wavelength. Another
limitation is linked to the relatively high absorption of hemoglobin
at 810 nm, which may pose problem when treating surgical
incisions. This in vitro study aimed at finding the optimal
wavelength for LASH, in particular with regards to phototype
compatibility and minimum absorption by blood.
Study: Eight human skin explants of phototypes I to VI,
harvested from abdominoplasties, as well as sheep blood plates
were irradiated using 810, 980, 1,064, 1,210, and 1,320 diode
lasers. Handpieces were designed to shape the beam profiles into
rectangular top hat to ensure optimum heating of the full skin
thickness. Surface temperature was monitored using an IR
camera. Micro-thermocouples were placed at 2 and 4 mm depth in
the explants. Temperatures were recorded at baseline and during
the irradiation. Irradiance was 4 W/cm 2 . Maximum temperature
and speed of heating were plotted and irradiance needed to
achieve 508C at 2 mm depth was extrapolated from these data.
Results: Among the four wavelengths tested, 1,210 nm is the
optimum compromise between efficacy of heating and minimum
variance due to phototype and blood. Contrary to other
wavelengths, no difference in heating patterns was observed at
1,210 and 1,320 nm when skin explants were soaked in blood or
not. Less than 18C gradient between surface and 2mm
temperature was observed at 1,210 nm compared with 48C for
1,320 nm.
Conclusion: This in vitro study demonstrate the optimal
characteristic of 1,210 nm wavelength for heating homogeneously
skin of all phototypes even in the presence of blood.
#13
American Society for Laser Medicine and Surgery Abstracts 5
TISSUE EFFECTS INDUCED BY Er;Cr:YSGG
LASER PULSES DELIVERED THROUGH A
RADIAL EMITTING FIBER STUDIED WITH HIGH
SPEED OPTICAL THERMOGRAPHY
Rudolf Verdaasdonk, Vladimir Lemberg, Albert
Veen van der, Stefan Been, Dmitri Boutoussov,
Werner Landgraf
VU University Medical Center, Amsterdam, Netherlands;
Optomix, Santa Clara, CA; University Medical Center Utrecht,
Utrecht, Netherlands; Biolase, Irvine, CA; Biolase Floss, Germany
Background: The Waterlase MD Er;Cr:YSGG laser system has
been successfully used for cutting, removing, shaping and
contouring of hard and soft tissues including endodontic and
periodontal therapies. To increase the efficiency of laser treatment
within the periodontal pockets, a radial emitting perio fiber tip
(RFPT) was developed.
Study: The optical, mechanical and thermal effects in tissue of
Er;Cr:YSGG laser pulses delivered through a radial emitting fiber
tip were studied using high speed optical thermography. High
speed color Schlieren techniques were used to visualize the extent
of heating and thermal relaxation after the laser exposure at
recording frame rate of 500 f/second (millisecond range). The
ablation process was observed with back-light illumination with
frame rates of speed imaging setup up to 8,000 f/second
(microsecond range). Pulses were delivered to the surface of a
polyacrylamide gel that acted as a transparent model tissue to
observe effect below the surface.
Results: The radial tip created a straight primary beam and a
secondary conical beam that ablated the tissue in the center
surrounded by ring of thermal effect at a short distance from the
surface. In contact with tissue, a small channel was created with
thermal ‘lobes’ to the side. The energy distributions correlated
well with ray-trace modeling of the radial tip design.
Conclusion: The special design radial emitting tip provides a tool
for effective cutting in combination with moderate thermal effects
to induce haemostasis during cutting in soft tissue and
decontamination in cavities like periodontal pockets. The tip
might also have potentials for precise surgical applications.
#14
IS IT POSSIBLE TO PERFORM LASER
RESHAPING WITHOUT DRAMATIC EFFECT ON
CHONDROCYTES?
Emil Sobol, Natalia Vorobieva, Olga Baum, Anatoly
Shekhter, Anna Guller
Institute on Laser and Information Technologies, Troitsk, Russia;
Medical Academy of Moscow, Moscow, Russia
Background: Laser reshaping of cartilage is a new, effective
technique which began to be used in otolaryngology and cosmetics
for correction of cartilage shape of the nose, ear and throat. The
main objective of the paper is to study the effect of various laser
settings on morphological alterations in chondrocytes during laser
reshaping of nasal septum.
Study: The nasal septums of the pigs have been treated using an
Erbium glass fiber laser of 1.56 mm in wavelength (Arcuo Medical,
Inc.) with an opto-thermo-mechanical contactor providing
mechanical pressing of the mucosa and delivering 1.56 mm laser
radiation to the spot of 3 mm in diameter. Two series of
experiments have been performed: (1) to determine the energy
threshold for stable laser reshaping and (2) to study the effect of
mechanical loading and irradiation of the fresh pig septum using
the threshold laser setting and different levels of exceeding
regimes. Histological analysis of the cartilage samples have been
performed to study the zones of altered chondrocytes, including
the sizes and positions of the necrotic zones.
Results: (1) Stable reshaping of pig nasal septum cartilage has
been achieved at laser power of 0.8 W, pulse length 0.5 seconds,
pulse spacing 0.2 seconds, exposure time of 3 seconds. (2) No
significant changes in chondrocyte shape and structure have been
observed for above laser setting. (3) Increase of laser power and
exposure time enhanced dramatically structural alterations in
chondrocytes.
Conclusion: The threshold laser settings allow to obtain stable
reshaping without significant alterations to chondrocytes.
Exceeding regimes of laser radiation lead to substantial
alterations (up to necrosis) of the cells. Since cell damage may