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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_103_библиотеки_им_акад_М_И_Перельмана
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10 Smartphone-Based Ophthalmic Imaging
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a
117
b
Fig. 10.4 The schematic diagram of the optical design of
the hardware (a) and a photograph of the Vistaro handheld device (b) [16]. Detailed optical design and description available at reference patent: EP3379994A4).
Notations: 100—retinal imaging apparatus, E—subject’s
eye, 105—illumination axis, 110—imaging axis, 115,
120—light sources arranged on the illumination axis,
160—objective lens, 165—porosity mirror, 170—porosity tube, 175—a collimating lens, 180—a converging
lens, 181—an imaging module placed along the imaging
axis (110), 125, 130—two ring-shaped shields, 135—a
diffuser, 140—rst condenser lens, 145—second con-
denser lens, 150—one projection lens, 155—a transparent
plate placed along the illumination axis (105). The rst
shield (125) has a central opaque portion on which an
observation light source (120) is mounted and an outer
pair of coaxial annular transparent regions. The diffuser
(135) is placed before the observation light source (120).
The second shield (130) has a central opening portion and
is mounted on the diffuser (135), which is adapted to
receive the illumination light beam emitted from the
observation light source (light-emitting diode [LED];
120) mounted on the rst shield (125)
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a
b
Fig. 10.5 Smartphone-based camera fundus photograph.
Left top: central retinal vein occlusion on FOP NM 10;
Left bottom: retinal hemorrhage on FOP NM 10. Right
top: a two-eld montage; Right bottom: a three-eld mon-
Clinical Applications: State-of-the-art
smartphone- based imaging devices like the
FOP and the Vistaro™ offer multiple benets
[16, 18–20, 23], such as reection artifacts-free
retinal images (Fig.10.5), wireless connectivity, secure cloud storage, and articial intelligence. The limitations include the need for
mydriasis (in those with small pupils for FOP)
and the non- availability of essential in-clinic
features such as autouorescence and uorescein angiography [7].
tage captured on the Vistaro™. (All images have been
reproduced under the Creative Commons Non-commercial
License)
10.4 Anterior Segment Imaging
The early possibility of imaging the anterior segment using smartphones was demonstrated by
Barsam etal. [24]. They used the iPhone 3G with
a standard Haag-Streit BM 900 slit lamp (Koniz,
Switzerland) under different diffuse illumination
settings [25]. It required holding the iPhone with
the one hand vertically and aligning the camera
lens closely with one of the viewing eyepieces
from the slit lamp biomicroscope while viewing
ab
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Fig. 10.6 (a) A prototype showing the use of a macro
lens with smartphones to view the anterior segment [26].
(b) A prototype to show ICL measurement using macro
the image on the iPhone [24]. Although this was
tedious for the operator, it paved the way for
many possibilities in imaging different parts of
the anterior segment using different attachments
to the smartphone like a macro lens, gonio lens,
etc. [25] (Fig.10.6). This advancement enabled
various clinical applications, including but not
limited to measuring the Implantable Collamer
Lens (ICL) vault, imaging the iridocorneal angle,
positioning toric intraocular lens (IOL) with a
protractor, and quantifying corneal endothelial
cells [24–28].
Using smartphones with adapters or lenses
requires patients to remain seated to obtain wellfocused images, which can be particularly challenging when dealing with elderly patients.
lenses clipped to a smartphone [27]. (All images have
been reproduced under the Creative Commons Noncommercial License)
magnication drum optics of slit lamps with
3-step or higher magnication. It is designed to
t snugly into the smartphone sensor at its lowest
magnication, requiring no additional adjustments between the eyepiece and the slit lamp
(Fig. 10.7) [29]. The depth of focus can be
adjusted to visualize different anterior structures
of the eye and adnexa. The plane of focus on the
phone can be adjusted according to the structure
imaged (Figs.10.7 and 10.8). When adjusting the
slice of focus toward the desired structure, a shallow focus effect is created in front of and behind
the focal point, resulting in a layered appearance.
By ensuring that the autofocus of the smartphone
app is disabled, the optical assembly ensures that
the position of the joystick of the slit lamp determines the focus (Fig.10.8) [29].
Clinical Applications: The smartphone-
10.4.1 Digitizing Analog Slit Lamps
based design ensures instant photo documentation. This process helps avoid errors associated
10.4.1.1 Anterior Imaging Module
(AIM)
The AIM (Remidio, Bangalore, India) digitizes a
slit lamp.
Technology: AIM uses high-quality antireection (AR) coated binocular optics combined
with a 70/30 beam splitter design, to match the
with manual documentation and reduces the time
required for diagnosis (Figs. 10.9 and 10.10).
Additionally, the photographer can click an
image while still seeing through the eyepiece, as
the design ensures that what the photographer
sees through the eyepiece gets documented, following the equivalence of foci in the design.
120
BEAM SPLI
Zoom lens drum
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MIRROR
AIM
IMAGING LENS
(20*80)
TTER
AIM
Ta rget Eye
Objective lens
CAMERA
LENS
EYEPIECE
(EWF 15X MG/20)
Mirror
Recording /
Capturing device
Focusing lens
Converging lens
Fig. 10.7 Optical design of the anterior imaging module. (Image reproduced under the Creative Commons Noncommercial License)
10.4.2 Portable Slit Lamps Based
onSmartphones
Smartphones can make slit lamps portable and
accessible for larger audiences, especially in
remote, resource-constrained settings. Several
adapter-based systems that utilize 3D printed
technology have been primarily used and validated for detecting and grading lens pathologies
[30]. Stand-alone systems with separate, standardized light sources have also been developed.
We describe one such device here: the PSL D20
Slit lamp Eyepiece
Beam splitter
[31]. Another hand-held slit lamp device is briey
described in Chap. 35.
10.4.2.1 PSL D20
The PSL D20 (Remidio, Bangalore, India) is a
novel, smartphone-based, portable digital slit
lamp with separate paths for illumination and
imaging to obtain high-quality, artifact-free anterior segment images (Fig.10.11) [31].
Technology: Light from the LED source
passes through the condenser lens as a single convergent beam and then through the illumination
lens. It is then reected via an anti- reection-
a
c
b
10 Smartphone-Based Ophthalmic Imaging
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Fig. 10.8 (a) Hardware
design of the anterior
imaging module (AIM).
(b) The AIM mounted
on a conventional slit
lamp. (c) Anterior
segment imaging on
AIM [29]. (All images
have been reproduced
under the Creative
Commons Noncommercial License)
121
Fig. 10.9 (a) An anterior segment image shows the
iris plane and lens in focus. (b) An anterior segment
image showing the plane of the cornea in focus. (All
images have been reproduced under the Creative
Commons Non- commercial License)
a
b
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cd
ef
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Fig. 10.10 Quality of images and range of pathologies
covered by the AIM. (a) Diffuse illumination showing a
congenital inferonasal coloboma (25×). (b) Optical section showing a clear lens (25×). (c) Diffuse illumination
depicting a hyper mature cataract with iris pigments on
the anterior lens surface (25×). (d) Retro illumination
shows a well-centered capsulorhexis with a single-piece
posterior chamber IOL in the capsular bag (16×). (e)
Gonioscopy showing an open inferior angle up to the ciliary body band with possible neovascularization of the
angle (25×). (f) Slit lamp biomicroscopy with a 90D volk
lens showing a healthy optic disc (25×). (All images have
been reproduced under the Creative Commons Noncommercial License)
Hyman Eye Illumination
t Phone
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coated right-angled prism to illuminate the eye.
Depending on the physician's requirement, the
entire illumination set-up is mounted on a slit
swiveling system that can be rotated to 45° on
both sides. The reected ray then passes along the
imaging plane, crossing two sets of imaging
lenses, that the smartphone captures after an optical magnication. The slit width can be controlled
between 0 and 12mm. The length of the slit is
xed at 12mm (Fig.10.11) [31].
The device features an adjustable headrest for
convenient manual focusing, ensuring that the
object of focus is visible on the phone screen.
This stability enables easy image capture by simply looking at the phone screen. The PSL D20
can be efciently operated using four controls: a
button to toggle between background illumination
lights (blue, green, and white LEDs) and, one to
capture the image, a knob to adjust the slit beam
intensity, all easily accessible within the grasp of
the thumb. The knob to adjust the variable slit
width is located on the swiveling optomechanical
unit underneath the prism. The controls offer user
convenience in adjusting to ambient light conditions while imaging a patient’s eye. To maintain
consistent angles during an examination, the
optomechanical illumination unit is supported by
a pair of ball spring plungers, providing the necessary friction (Fig.10.12) [31].
Clinical Applications: A pilot study demonstrated the PSL D20’s performance in photo
documentation and its feasibility in teleophthalmology practice [31]. Optical sections across the
lens (Fig.10.13a, e, and f) and retro illumination
(Fig.10.13h) allow for objective cataract grading (as per the Lens Opacities Classication
System (LOCS) III scale). The optic disc evaluation (Fig.10.13i) was done using a 90D lens, and
the green lter enhances the delineation of conjunctival blood vessels (Fig.10.13d). Fluorescent
dye with a blue lter can evaluate the tear lm
break- up time (TBUT). Additionally, the PSLD20 has been validated for asynchronous and
synchronous teleconsultation [31].
Fig. 10.11 The optical
design of the PSL D20
(Image has been
reproduced under the
Creative Commons
Non-commercial
License)
Prism
Smar
Condenser lens
Light Source
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Fig. 10.12 The PSL
D20 hardware along a
swiveling
optomechanical unit (All
images have been
reproduced under the
Creative Commons
Non-commercial
License)
A. Sivaraman et al.
While we await large-scale, real-world studies to further validate the clinical impact of
smartphone- based anterior segment devices like
the AIM and PSL D20, they hold promise with
their unique set of advantages (portability,
unique design, connectivity, dedicated patientmanagement software, HIPAA-compliant stor-
age servers), [29, 31] and shortcomings
(concomitant use of gonioscope lenses and
applanation tonometry is not possible, difcult
retroillumination, limited smartphone sensor
resolution, and limitations in magnication for
viewing corneal endothelium and for estimating
anterior chamber are).
10 Smartphone-Based Ophthalmic Imaging
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abc
def
ghi
125
Fig. 10.13 The quality of images captured by the PSL
D20 [31]. (a) A narrow slit beam is projected at an angle
of 45°. It cuts an optical section through the clear lens
obtained at a magnication equivalent to 16× on standard
slit lamp. (b) Diffuse illumination provides evenly balanced lighting. This image shows a dense arcus senilis in
a pseudophakic eye captured at a magnication equivalent
of 10× on standard slit lamp. (c) Diffuse illumination
showing diffuse conjunctival hyperemia captured at a
magnication equivalent of 10× on standard slit lamps.
(d) Conjunctival vessels are better visualized in green lters (captured at a magnication equivalent of 10× on
standard slit lamps). (e) A narrow slit beam cuts an optical
section through the lens with a nuclear cataract (LOCS III
grade NO 4 and NC 4; captured at a magnication equiva-
10.5 Articial Intelligence
inSmartphone-Based
Ophthalmic Imaging Devices
Articial intelligence (AI) is a cutting-edge technology capable of handling and analyzing large
amounts of data. Since smartphones are extensively used to capture image-based data; integrating AI can aid in analyzing and processing this
lent of 16× on standard slit lamps). (f) A narrow slit beam
cuts an optical section through the lens with a nuclear
cataract (LOCS III grade NO 3 and NC 3; captured at a
magnication equivalent of 10× on standard slit lamps).
(g) Retroillumination technique showing a good fundal
glow with no peripheral cortical or posterior subcapsular
opacities (captured at a magnication equivalent of 10×
on standard slit lamps). (h) Retroillumination imaging
showing posterior subcapsular cataract (LOCS grade P5;
captured at a magnication equivalent to 10×). (i) PSL
biomicroscopy with a 90D lens shows clear media with a
normal optic disc in a view captured at a magnication
equivalent of 10× on standard slit lamps. (All images have
been reproduced under the Creative Commons Noncommercial License)
data to generate point-of-care diagnostic support
output. In ophthalmology, AI has shown promising results over the past decade in detecting various conditions like DR, age-related macular
degeneration (AMD), retinopathy of prematurity
(ROP), glaucoma, cataracts, and other anterior
segment diseases [32].
Most AI algorithms used for ophthalmic diag-
nosis have been cloud-based (for example, Google
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AI, EyeArt, IDx-DR), requiring a working internet connection, which can be challenging in
remote areas with limited internet access [33]. To
address this, integrating AI algorithms into smartphone-based devices can make ophthalmic diagnosis more accessible to a larger population.
Initially intended for screening and triaging
patients for specialist referrals, AI algorithms on
smartphones can also facilitate autonomous decisions in the absence of ophthalmic professionals,
improving eyecare equity [34, 35]. This requires
robust development with diverse datasets, no
inherent bias, and real-world testing in the popu-
lation for which it is intended to be used. Several
AI algorithms have been validated on smartphonebased devices (either with adapters or on a standalone basis) for screening DR and glaucoma;
these have demonstrated high diagnostic accuracies and have the potential to bridge gaps in eyecare access for a broader population [32–41].
An ofine AI algorithm can overcome the
limitation of the availability of an internet connection. The Medios AI algorithm is one such
innovation implemented after real-world studies
to detect referable DR and glaucoma (Fig.10.14)
[20, 33, 34, 36, 37].
Fig. 10.14 The user Interface of Medios AI, an ofine AI algorithm that can generate a report within seconds of
image capture highlighting the lesions (left) for referable DR and for referable glaucoma (right)
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