Translational Vision Science & Technology,
Год журнала:
2024,
Номер
13(12), С. 36 - 36
Опубликована: Дек. 30, 2024
Purpose:
To
assess
the
safety
of
acoustic
radiation
force
optical
coherence
elastography
in
crystalline
lens
situ.
Methods:
Acoustic
(ARF)
produced
by
an
immersion
single-element
ultrasound
transducer
(nominal
frequency
=
3.5
MHz)
was
characterized
using
a
needle
hydrophone
and
used
for
(OCE)
lens.
Preamplified
signals
at
50,
100,
250,
500,
750,
1000,
1250
mV
peak
amplitude
were
tested
on
ex
vivo
porcine
eyes
(n
21).
Three-dimensional
tomography
(OCT)
confocal
microscopy
images
acquired
before
after
ARF
exposure
to
each
signal
determine
damage.
Results:
The
intensity
100-mV
preamplified
input
demonstrated
signal-to-noise
ratio
high
enough
tracking
elastic
wave
propagation
spatial-peak
pulse-average
(SPPA)
24.1
W/cm²
mechanical
index
(MI)
0.46.
SPPA
lower
than
U.S.
Food
Drug
Administration
(FDA)
limit
(28
W/cm2),
but
MI
twice
(0.23).
OCT
structural
showed
damage
only
levels
exceeding
1150
W/cm2
3.2
MI,
respectively.
Conclusions:
that,
even
when
exceeded
FDA
recommendations
(>100
mV),
no
noticeable
observed.
Although
further
reduction
is
necessary
meet
limits,
ARF-based
shows
promise
safe
clinical
translation
quantitatively
characterizing
lenticular
biomechanical
properties.
Translational
Relevance:
This
work
assessed
standards
be
human
according
limits.
Bioengineering,
Год журнала:
2023,
Номер
10(7), С. 754 - 754
Опубликована: Июнь 24, 2023
Assessing
corneal
biomechanics
in
vivo
has
long
been
a
challenge
the
field
of
ophthalmology.
Despite
recent
advances
optical
coherence
tomography
(OCT)-based
elastography
(OCE)
methods,
controversy
remains
regarding
effect
intraocular
pressure
(IOP)
on
mechanical
wave
propagation
speed
cornea.
This
could
be
attributed
to
complexity
and
difficulties
associated
with
conducting
shear-wave
OCE
measurements.
We
constructed
simplified
artificial
eye
model
silicone
cornea
controllable
IOPs
performed
surface
measurements
radial
directions
(54-324°)
at
different
IOP
levels
(10-40
mmHg).
The
results
demonstrated
increases
speeds
(mean
±
STD)
from
6.55
0.09
m/s
(10
mmHg)
9.82
0.19
(40
mmHg),
leading
an
estimate
Young's
modulus,
which
increased
145.23
4.43
kPa
326.44
13.30
kPa.
Our
implementation
highlighted
that
impact
modulus
(ΔE
=
165.59
kPa,
IOP:
10-40
was
more
significant
than
stretching
15.79
relative
elongation:
0.98-6.49%).
study
sheds
light
potential
advantages
using
represent
response
human
during
measurement
provides
valuable
insights
into
wave-based
for
future
studies.
Optics,
Год журнала:
2023,
Номер
4(4), С. 584 - 594
Опубликована: Ноя. 17, 2023
The
cornea
is
the
optical
window
to
brain.
Its
and
structural
properties
are
responsible
for
transparency
vision.
shape,
elasticity,
rigidity,
or
stiffness
due
its
biomechanical
properties,
whose
stability
results
in
ocular
integrity
intraocular
pressure
dynamics.
Here,
we
report
vivo
observations
of
shape
changes
alterations
human
induced
by
acoustic
wave
within
frequency
range
50–350
Hz
sound
level
90
dB.
central
corneal
thickness
(CCT)
eccentricity
(e2)
were
measured
using
Scheimpflug
imaging
[corneal
hysteresis
(CH)
(IOP)]
assessed
with
air-puff
tonometry
six
young,
healthy
volunteers.
At
specific
150
frequency,
variations
e2
CCT
0.058
7.33
µm,
respectively.
Biomechanical
also
observed
both
IOP
(a
decrease
3.60
mmHg)
CH
(an
increase
0.40
mmHg).
Assessing
corneal
biomechanics
in
vivo
has
long
been
a
challenge
the
field
of
ophthalmology.
Although
recent
wave-based
optical
coherence
elastography
(OCE)
methods
have
shown
promise
this
area,
effect
intraocular
pressure
(IOP)
on
mechanical
wave
propagation
cornea
remains
unclear.
To
address
this,
we
constructed
an
artificial
eye
model
and
performed
surface
OCE
measurements
radial
directions
(54–324°)
silicone
at
varying
IOP
levels
(10–40
mmHg).
The
results
demonstrated
increases
speeds
(mean
±
STD)
from
6.55
0.09
m/s
(10
mmHg)
to
9.82
0.19
(40
mmHg),
leading
estimate
Young’s
modulus,
which
increased
exponentially
145.23
4.43
kPa
326.44
13.30
kPa.
Our
implementation
highlighted
that
impact
modulus
(ΔE
=
165.59
kPa,
IOP:
10–40
was
more
significant
than
stretching
15.79
relative
elongation:
0.98%–6.49%).
study
sheds
light
potential
using
research
for
biomechanics.
Furthermore,
it
is
critical
consider
measurement
when
utilizing
clinical
settings
enhanced
assessment
Photonics,
Год журнала:
2024,
Номер
11(6), С. 524 - 524
Опубликована: Май 31, 2024
Corneal
biomechanics
is
a
hot
topic
in
ophthalmology.
The
biomechanical
properties
(BMPs)
of
the
cornea
have
important
implications
management
and
diagnosis
corneal
diseases
such
as
ectasia
keratoconus.
In
addition,
characterization
BMPs
crucial
to
model
predictability
surgery
intervention,
outcomes
refractive
or
follow-up
diseases.
behavior
governed
by
viscoelastic
that
allow,
among
other
structural
implications,
damping
excess
intraocular
pressure
reduction
damage
optic
nerve.
Currently,
most
versatile
complete
methods
measure
viscoelasticity
are
based
on
air-puff
applanation.
However,
these
lack
ability
directly
viscosity.
aim
this
work
propose
new
methodology
analysis
measurements
through
standard
linear
solid
(SLSM)
provide
analytical
expressions
separately
calculate
elastic
time-dependent
(corneal
retardation
time
viscosity)
properties.
results
show
mean
values
elasticity
(E),
viscosity
(Ƞ)
(τ)
sample
200
young
healthy
subjects.
influence
viscoelasticity,
high-order
aberrations
optical
transparency
investigated.
Finally,
SLSM
fed
back
from
experimental
E
Ƞ
employed
compare
creep
relaxation
response
between
normal,
an
ocular
hypertension
patient
Ortho-K
user.
strongly
affected
(IOP);
however,
hysteresis
(CH)
not
enough
be
risk
factor
glaucoma
progression.
Low
CH
can
accompanied
high
low
depending
IOP
threshold
which
trends
reversed.
PLoS ONE,
Год журнала:
2024,
Номер
19(11), С. e0311849 - e0311849
Опубликована: Ноя. 12, 2024
Image
segmentation
of
the
corneal
endothelium
with
deep
convolutional
neural
networks
(CNN)
is
challenging
due
to
scarcity
expert-annotated
data.
This
work
proposes
a
data
augmentation
technique
via
warping
enhance
performance
semi-supervised
training
CNNs
for
accurate
segmentation.
We
use
unique
process
images
and
masks
involving
keypoint
extraction,
Delaunay
triangulation,
local
affine
transformations,
mask
refinement.
approach
accurately
captures
natural
variability
endothelium,
enriching
dataset
realistic
diverse
images.
The
proposed
method
achieved
an
increase
in
mean
intersection
over
union
(mIoU)
Dice
coefficient
(DC)
metrics
17.2%
4.8%
respectively,
task
endothelial
on
multiple
CNN
architectures.
Our
strategy
successfully
models
images,
thereby
enhancing
generalization
capabilities
medical
image
cell
tasks.
Translational Vision Science & Technology,
Год журнала:
2024,
Номер
13(12), С. 36 - 36
Опубликована: Дек. 30, 2024
Purpose:
To
assess
the
safety
of
acoustic
radiation
force
optical
coherence
elastography
in
crystalline
lens
situ.
Methods:
Acoustic
(ARF)
produced
by
an
immersion
single-element
ultrasound
transducer
(nominal
frequency
=
3.5
MHz)
was
characterized
using
a
needle
hydrophone
and
used
for
(OCE)
lens.
Preamplified
signals
at
50,
100,
250,
500,
750,
1000,
1250
mV
peak
amplitude
were
tested
on
ex
vivo
porcine
eyes
(n
21).
Three-dimensional
tomography
(OCT)
confocal
microscopy
images
acquired
before
after
ARF
exposure
to
each
signal
determine
damage.
Results:
The
intensity
100-mV
preamplified
input
demonstrated
signal-to-noise
ratio
high
enough
tracking
elastic
wave
propagation
spatial-peak
pulse-average
(SPPA)
24.1
W/cm²
mechanical
index
(MI)
0.46.
SPPA
lower
than
U.S.
Food
Drug
Administration
(FDA)
limit
(28
W/cm2),
but
MI
twice
(0.23).
OCT
structural
showed
damage
only
levels
exceeding
1150
W/cm2
3.2
MI,
respectively.
Conclusions:
that,
even
when
exceeded
FDA
recommendations
(>100
mV),
no
noticeable
observed.
Although
further
reduction
is
necessary
meet
limits,
ARF-based
shows
promise
safe
clinical
translation
quantitatively
characterizing
lenticular
biomechanical
properties.
Translational
Relevance:
This
work
assessed
standards
be
human
according
limits.
