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ab
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A. Panigrahi et al.
tion of the iris in the left eye; the right eye
appeared normal, except for a temporally
pulled pupillary ruff (Fig.18.8a). Hence, right
eye primary open-angle glaucoma and left
eye neovascular glaucoma (NVG) were diagnosed. A detailed gonioscopic evaluation
revealed the presence of a single strand of
neovascularization at the angle in the temporal
angle corresponding to the site of the pulled
pupillary ruff, visible only at higher magnications (Fig.18.8b). The diagnosis was eventually changed to NVG for both eyes. Thus, a
detailed gonioscopic evaluation helped make
an appropriate diagnosis.
Other important uses of gonioscopy are identifying angle occludability, staging angle closure, and proper management. Labeling an
occludable angle open after a brief screening
under high illumination by a novice is a common
mistake. Misdiagnosing angle closure glaucoma
(ACG) as open-angle glaucoma (OAG) can be
catastrophic, considering the aggressive course
and potentially blinding nature of ACG. Most
iridotrabecular contact in ACG occurs during
pupil dilation when the risk of a pupillary block
is the highest and the amount of iridotrabecular
contact is maximum. This results in progressive
damage to the PTM, resulting in outow dysfunction and elevated IOP.Hence, it is valuable
to simulate this aggravating condition as closely
and safely as possible to assess the actual risk of
development and progression of glaucoma. To
assess angle closure, it is important to determine
the angle structures under the thinnest slit and
dimmest illumination possible (Fig. 18.9a and
b), which permits a proper estimation of the
occludability.
Fig. 18.8 An anterior segment photograph of the
patient’s right eye (a) shows ruff atrophy with early ectropion uvea in the temporal pupillary margin (white arrow).
a
Right (b): gonioscopic examination revealed an open
angle with the presence of a single new vessel (black
arrow), crossing the scleral spur to reach Schwalbe’s line
b
Fig. 18.9 Goniophotograph of an occludable angle. Only
Schwalbe’s line is seen on minimal illumination (a). Upon
increasing the width and brightness of the slit, pigmenta-
tion of the posterior trabecular meshwork can be seen (b),
signifying occludability with appositional closure
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18.7 Systems forAutomated
Goniophotography
Recently, systems for goniophotography have
been developed to image the anterior chamber
angle without using a conventional gonioscope,
thus reducing human variations and errors. These
systems utilize a contact lens system and coupling agent, similar to a conventional gonioscope
system. Examples of such specialized systems
include the following.
1. RetCam, NGS-1 automated gonioscope, the
GonioPEN, and axicon lens-assisted gonioscopy [6]. The RetCam (Natus Medical
Incorporated, Pleasanton, CA) is a handheld
retinal and angiographic camera primarily
developed to screen retinopathy of prematurity. It can also visualize the anterior chamber
angle using its B1200 lens with a 120° eld of
view. It has shown good sensitivity, specicity, and excellent diagnostic performance for
detecting gonioscopic angle closure, especially when using the denition of twoquadrant angle closure for diagnosis [7].
2. The NGS-1 automated gonioscope (Nidek,
Gamagori, Japan) is a recently commercialized contact-based automated goniophotography device that can capture 16 sections over a
360° angle in less than 1min [8, 9]. The main
advantage of this system is the shorter image
capture time and learning curve compared to
manual gonioscopy. However, poor resolution
of the trabecular meshwork due to defocus
remains a problem. Hence, the jury is still not
out regarding using this system in routine
clinical practice.
3. The GonioPEN combines a miniaturized
charge-coupled diode camera with a lightemitting diode, both integrated into a probe
that can be used as a slit-lamp attachment. It is
placed near the limbus to visualize structures
of the opposite iridocorneal angle [10].
4. The axicon lens-assisted gonioscopy is a
potential alternate mechanism for gonioscopic
visualization and imaging, which is currently
under development. It integrates the concept
of Bessel beam microscopy, which enables
accurate imaging of the anterior chamber
angle to a spatial resolution of 3 μm. It has
been used to visualize the anterior chamber
angle in bovine [11] and rabbit [12] eyes; further studies are needed to validate this technology for use in human eyes.
18.8 Technological Adjuncts
toGonioscopy
Ultrasound biomicroscopy (UBM) was one of
the rst devices to aid in gonioscopic diagnosis.
It employs high-frequency ultrasonic waves,
which help in the detailed imaging of the anterior
chamber and angle structures. It is instrumental
in visualizing the morphology of the ciliary body.
It is useful in detecting angle closure glaucoma,
especially differentiating between the major subgroups of primary angle closure glaucoma
(PACG). Iridotrabecular contact with a convex
iris conguration suggests a pupillary block
mechanism (Fig. 18.10a). A deep central and a
shallow peripheral anterior chamber due to an
anteriorly rotated ciliary body (Fig.18.10b), with
partial or complete obliteration of the iridociliary
sulcus, suggests a plateau iris conguration. A
ciliary body cyst may be present, causing an anterior shift in the ciliary body (Fig.18.10c). This
leads to an appearance similar to the plateau iris
conguration and is termed as pseudo plateau iris
conguration. The latter two can be gonioscopically identied based on the presence of “sine
wave iris conguration” and “lumpy, bumpy
appearance,” respectively. Differentiation
between the three groups is necessary, as the
pupillary block mechanism is amenable to laser
iridotomy, whereas the other two are refractory.
Occasionally, a ciliary body melanoma may be
noted, leading to secondary angle closure. UBM
is also used in children with hazy corneas to evaluate the angle of closure. This allows differentiation between primary congenital glaucoma and
secondary glaucoma, aiding in prognostication
and decision-making.
Recently, swept-source anterior segment optical coherence tomography (AS-OCT) has been
used in the stratication of the risk of develop-
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A. Panigrahi et al.
Fig. 18.10 Ultrasound biomicroscopy (UBM) ndings
of the three mechanisms of primary angle closure mechanism: pupillary block (a), plateau iris conguration (b),
ment of PACG. It employs a beam of longer
wavelength (1310 nm) and lower penetration
than retinal OCT, hence facilitating the detailed
imaging of the AC. Recent studies have shown
that the detection of the anatomic angle closure
by AS-OCT parameters like angle opening distance and trabecular iris space area is more
strongly correlated to the risk of progression to
glaucoma, as compared to gonioscopic angle closure [13–15]. This result is not an anomaly;
where human evaluation is tainted with variations due to illumination, pressure, eye movement, and the individuality of the examiner,
machines are highly automated with the ability to
simulate the optimal conditions for imaging. A
360° evaluation of the angle using AS-OCT to
rule out any form of iridotrabecular contact
before delaying the institution of laser iridotomy
may help prevent progression and thereby reduce
the burden of angle closure disease.
18.9 Gonioscopy andUsing
Articial Intelligence
With the latest technological advancement, articial intelligence is increasingly used for classifying medical images, often performing better than
manual grading [16, 17]. It is used in aiding
gonioscopic diagnosis of open-angle and angle
closure glaucoma. Both these diagnoses are
enabled by sequential and segmental SS-OCT
scans, which are further analyzed by various
deep learning (DL) models. The efcacy of these
DL models is assessed by the area under curve
and pseudo plateau iris conguration due to multiple ciliary body cysts (c)
(AUC) enclosed by the receiver operator characteristic curves, with a higher AUC indicating a
more accurate model.
Many DL models have been used in assessing
and further classifying angle closure disease.
Earlier models used scans obtained on UBM
[18], or a single AS-OCT [19] or SS-OCT [20]
scan obtained over either meridian, where the
vertical scans were more accurate than the horizontal scans for detecting angle closure. The latest advancements include the circumferential
assessment of angle using SS-OCT scans
obtained over 360° of the anterior chamber angle
(Casia 2, Tomey Corporation, Japan). A recent
study using a novel DL algorithm using circumferential SS-OCT scans has noted that the cut-off
of ≥35° of circumferential iridotrabecular contact was the most accurate for diagnosing gonioscopic angle closure, with high sensitivity and
specicity [21]. A lower cut-off value, although
more sensitive, has extremely low specicity for
diagnosing angle closure. Similarly, a higher
cut- off has very low sensitivity for diagnosing
angle closure, despite being extremely specic.
Interestingly, the AUC noted in this study with a
35% cut-off was similar to the performance of a
semiautomated built-in software called the “ITC
index” [22]. Calculation of this ITC index
depends on the manual marking of the scleral
spur by the operator; hence, it is prone to interobserver variability and aberrant results. On the
other hand, DL models are entirely automated
and do not require manual marking of the scleral
spur, resulting in a faster and more accurate
assessment of gonioscopic angle closure.
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DL models also can classify different morphological patterns of juvenile open-angle glaucoma
(JOAG) into various clusters. These clusters can
be divided by the iris and gonioscopic features,
age of onset, and baseline IOP. A recent study
revealed that abnormal iris morphology and a
high iris insertion correlate more closely with a
higher IOP and worse visual prognosis [23].
Such a phenotypic classication of JOAG can
help in the stratication of severity when screening such patients.
18.10 Conclusion
This chapter explored the optics and techniques
of gonioscopy and highlighted its signicance in
evaluating and managing glaucoma. The technological advances discussed can assist manual
gonioscopy for better diagnoses and management
of glaucoma but cannot replace it. Hence, mastery of this technique is essential. Gonioscopy is
an acquired art, and optimal utilization of the
procedure requires considerable personal experience. However, awareness of the sources of error
and the proper interpretation of the ndings
would result in a shorter learning phase.
Funding None.
Disclosure None.
References
1. Scheie HG.Width and pigmentation of the angle of
the anterior chamber; a system of grading by gonioscopy. AMA Arch Ophthalmol. 1957;58(4):510–2.
2. Spaeth GL. The normal development of the human
anterior chamber angle: a new system of descriptive
grading. Trans Ophthalmol Soc U K. 1971;91:709–39.
3. Spaeth GL. Gonioscopy: uses old and new. The
inheritance of occludable angles. Ophthalmology.
1978;85(3):222–32.
4. Spaeth GL, Azuara-Blanco A, Araujo SV, Augsburger
JJ. Intraobserver and interobserver agreement in
evaluating the anterior chamber angle conguration by ultrasound biomicroscopy. J Glaucoma.
1997;6(1):13–7.
5. Shaffer RN.Primary glaucomas Gonioscopy, ophthalmoscopy and perimetry. Trans Am Acad Ophthalmol
Otolaryngol Am Acad Ophthalmol Otolaryngol.
1960;64:112–27.
6. Porporato N, Bell KC, Perera SA, Aung T. Nonoptical coherence tomography modalities for
assessment of angle closure. Taiwan J Ophthalmol.
2022;12(4):409–14.
7. Perera SA, Baskaran M, Friedman DS, Tun TA, Htoon
HM, Kumar RS, etal. Use of EyeCam for imaging the
anterior chamber angle. Invest Ophthalmol Vis Sci.
2010;51(6):2993–7.
8. Matsuo M, Mizoue S, Nitta K, Takai Y, et al.
Intraobserver and interobserver agreement among
anterior chamber angle evaluations using automated
360-degree gonio-photos. Huang J, editor. PLoS One.
2021;16(5):e0251249.
9. Teixeira F, Sousa DC, Leal I, Barata A, et al.
Automated gonioscopy photography for iridocorneal
angle grading. Eur J Ophthalmol. 2020;30(1):112–8.
10. Shinoj VK, Murukeshan VM, Baskaran M, Aung
T. Integrated exible handheld probe for imaging
and evaluation of iridocorneal angle. J Biomed Opt.
2015;20(1):016014.
11. Perinchery SM, Shinde A, Fu CY, et al. High resolution iridocorneal angle imaging system by axicon lens
assisted gonioscopy. Sci Rep. 2016;6:30844.
12. Hong XJJ, Suchand Sandeep CS, etal. Noninvasive
and noncontact sequential imaging of the Iridocorneal
angle and the cornea of the eye. Transl Vis Sci
Technol. 2020;9(5):1.
13. Gupta B, Angmo D, Yadav S, etal. Quantication of
Iridotrabecular contact in primary angle-closure disease. J Glaucoma. 2020;29(8):681–8.
14. Zhang X, Guo PY, Lin C, et al. Assessment of iris
trabecular contact in eyes with Gonioscopic angleclosure. Ophthalmology. 2023;130(1):111–9.
15. Xu BY, Friedman DS, Foster PJ, etal. Ocular biometric risk factors for progression of primary angle closure disease: the Zhongshan angle closure prevention
trial. Ophthalmology. 2022;129(3):267–75.
16. Carin L, Pencina MJ.On deep learning for medical
image analysis. JAMA. 2018;320(11):1192–3.
17. Grzybowski A, Brona P, Lim G, etal. Articial intelligence for diabetic retinopathy screening: a review.
Eye Lond Engl. 2020;34(3):451–60.
18. Shi G, Jiang Z, Deng G, etal. Automatic classication
of anterior chamber angle using ultrasound biomicroscopy and deep learning. Transl Vis Sci Technol.
2019;8(4):25.
19. Fu H, Baskaran M, Xu Y, etal. A deep learning system for automated angle-closure detection in anterior
segment optical coherence tomography images. Am J
Ophthalmol. 2019;203:37–45.
20. Xu BY, Chiang M, Chaudhary S, et al. Deep learning classiers for automated detection of Gonioscopic
angle closure based on anterior segment OCT images.
Am J Ophthalmol. 2019;208:273–80.
224
https://t.me/med1917
A. Panigrahi et al.
21. Porporato N, Tun TA, Baskaran M, etal. Towards “automated gonioscopy”: a deep learning algorithm for 360°
angle assessment by swept-source optical coherence
tomography. Br J Ophthalmol. 2022;106(10):1387–92.
22. Baskaran M, Ho SW, Tun TA, et al. Assessment
of circumferential angle-closure by the iris–
trabecular contact index with swept-source optical coherence tomography. Ophthalmology.
2013;120(11):2226–31.
23. Birla S, Gupta D, Somarajan BI, etal. Classifying juvenile onset primary open angle glaucoma using cluster
analysis. Br J Ophthalmol. 2020;104(6):827–35.
Optic Disc Photography
https://t.me/med1917
K.GowriPratinya , AparnaRao , PallaviRay,
andBhoomiThakkar
19
19.1 Introduction
Ophthalmic disc photography is a valuable tool in
glaucoma care. It allows precise documentation
and analysis of the optic disc, which is crucial for
glaucoma evaluation. The history parallels the
evolution of imaging technology and contributed
signicantly to diagnosing and managing glaucoma and several other ocular conditions. Using
specialized software installed in the cameras, it
provides accurate optic disc images for objective
quantication and characterization of the disc for
enhanced patient care. This chapter explores the
historical developments, equipment, techniques,
image interpretation, clinical applications, and
future directions of optic disc photography.
19.2 History ofOphthalmic
Photography
The history of ophthalmic photography dates
back to the mid-nineteenth century when
Jackman and Webster published the rst retinal
image of a living human subject [1]. The optic
disc was faintly visible due to strong reexes
from the cornea. It was not until the twentieth
century that fundus photography became an
established technique for optic disc imaging [2].
In 1911, a large reex-free ophthalmoscope
invented by Alvar Gullstrand viewed the fundus
through the upper pupil reducing unwanted
reexes from the cornea [3]. the Zeiss-Nordenson
camera was designed and introduced in 1925
using this principle [4]. These cameras allowed
for more accurate and standardized optic disc
measurements. The advent of digital imaging in
the 1990s enabled good-quality optic disc
photography.
19.3 Optic Nerve Photography
Optic disc photography has become an important
part of glaucoma screening for objective and
quantitative measurements enabling early detection and management. It also plays a vital role in
telemedicine.
K. G. Pratinya · A. Rao (*)
Kallam Anji Reddy Campus, L V Prasad Eye
Institute, Hyderabad, India
e-mail: kolipaka.pratinya@lvpei.org; aparna@lvpei.org
P. Ray · B. Thakkar
Mithu Tulsi Chanrai Campus, L V Prasad Eye
Institute, Bhubaneswar, India
e-mail: pallavi.ray@lvpei.org;
bhoomi.Thakkar@lvpei.org
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024
T. Das, P. Satgunam (eds.), Ophthalmic Diagnostics, https://doi.org/10.1007/978-981-97-0138-4_19
19.3.1 Monoscopic Color Fundus
Photography
Monoscopic color fundus photography is a widely
used technique for capturing detailed retina and
optic disc images. Monoscopic photography pro-
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Fig. 19.1 A color fundus monoscopic photograph of the
right eye (left) showing a tilted suspicious myopic disc. A
color fundus monoscopic photograph of the right eye
duces a two-dimensional optic disc image by
employing a single-lens camera system. This
technique provides quick images for reference,
but due to the inability of the technique to capture
the three-dimensional structure of the optic disc,
at times, assessing the depth and contour of the
optic nerve head is often challenging. This is more
acutely observed in myopic disc assessment,
where the cupping can be very shallow (Fig.19.1).
19.3.2 Red-Free Photography
Red-free photography, also known as green or
blue lter photography, is an imaging technique
to visualize the retinal nerve ber layer (RNFL).
It captures images of the optic disc and retina
with a specic lter that blocks red light, allowing only green or blue light to pass. In red-free
photography, the RNFL appears as a darker shade
against the background of the retinal layers.
Since the RNFL contains melanin, a pigment that
absorbs green and blue light more than red light,
eliminating red light (which is predominantly
absorbed by the other retinal layers) can selectively accentuate the RNFL, making it easier to
detect defects; this is red-free photography.
(right) showing a glaucomatous disc with inferior excavation and inferior nerve ber layer thinning (yellow arrow)
Clinical application: Red-free photography
reduces the visibility of the blood vessels by minimizing their background contrast, allowing the
identication of the RNFL (Fig.19.2).
19.3.3 Stereoscopic Images
Stereoscopic images of the optic disc are obtained
by taking two images of the optic disc from
slightly different angles, mimicking the binocular
vision that our eyes naturally provide. In the stereoscopic camera system, either two camera
lenses or two separate cameras are positioned
slightly apart horizontally. This simultaneous
capture of the optic disc from slightly different
angles creates the necessary parallax and enables
the brain to perceive the depth. Once the two
images are captured, they can be viewed together
using a stereoscope or a specialized device that
allows the observer to merge the two images into
a single, three-dimensional perception (Fig.19.3).
The stereoscope typically contains lenses that
direct each image to the corresponding eye,
allowing the brain to fuse the images and perceive the three-dimensional structure of the optic
disc.
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Fig. 19.2 Color fundus (left) and red-free (right) monoscopic photographs of the right eye with inferior and superior
retinal nerve ber layer defects; the defects are more clearly visible in the red-free photographs (yellow arrows)
227
server agreement than monoscopic assessments.
Parkin etal. [7] and Varma etal. [5] have evaluated
the intraobserver and interobserver agreement for
evaluating the optic disc for glaucoma under monoscopic and stereoscopic conditions; the agreement
was similar under both conditions, Yang et al. [8]
have reported better performance with stereoscopic
images among general ophthalmologists.
Fig. 19.3 Examining the stereoscopic optic disc photographs with a stereoscope
Clinical application: With these stereoscopic
images, clinicians gain a better understanding of
features of cup-to-disc ratio, neuroretinal rim
abnormalities, and other structural changes for
better diagnosis and management of glaucoma.
However, stereoscopic optic disc imaging may
provide higher estimates of the cup-disc ratio and
lower estimates of the neuroretinal rim area [5].
Morgan etal. [6] compared monoscopic and stereoscopic images of the optic disc using software
for the digital stereoscopic analysis of optic disc stereo pairs and found that digital stereoscopic optic
disc assessment provides higher levels of interob-
19.4 Retinal Camera forOptic
Disc Photography
19.4.1 Non-mydriatic Fundus
Cameras
Non-mydriatic fundus cameras are designed to
capture high-resolution images of the fundus,
including the optic disc, without pupil dilation.
They combine optical elements to capture clear
and detailed images of the fundus. These optical
components typically include lenses, mirrors,
and lters. The lenses focus the light onto the
retina, and the mirrors are used to direct the light
to form the image. Filters enhance contrast and
selectively capture specic wavelengths of light.
Non-mydriatic fundus cameras employ pupil
detection and alignment systems to ensure accu-
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rate and centered imaging. Infrared light is commonly used as it causes less discomfort for the
patient and allows better visualization of fundus
structures. The camera’s software then adjusts
the focus and alignment to capture the desired
region, typically the optic disc, with high precision and clarity. By eliminating the need for pupil
dilatation, these cameras provide a more convenient and patient-friendly approach to fundus
imaging without compromising the quality of the
image [9].
K. G. Pratinya et al.
19.4.2 Handheld Fundus Cameras
Handheld fundus cameras are portable and compact imaging devices used to capture an image
of the optic disc and retina. These are lightweight, compact, and portable, allowing effortless maneuverability and use in various clinical
settings. They typically consist of a camera unit,
an imaging module, a light source, a display
screen, and controls for image capture and
adjustment. Handheld fundus cameras offer various methods for image capture. They may have
a built-in camera module or use attachments
that can be connected to smartphones or other
mobile devices. Some cameras feature a liveview display that shows real-time images as the
operator aligns the camera with the patient’s
eye. Images can be captured with a hand-operated button or by activating a foot pedal. The
image quality may be variable due to operator
variability. Additionally, the eld of view may
be narrower than larger cameras, requiring multiple images to obtain an image of the entire
fundus. However, they address the growing
demand for retinal imaging in different clinical
scenarios like those for screening children,
school screenings, and screening of bed-ridden
patients [10]. Integrating smartphone technology and miniature tabletop versions make these
cameras increasingly portable, convenient, and
accessible (Fig.19.4).
Fig. 19.4 Fundus photography in a school screening
using a handheld non-mydriatic smartphone-integrated
fundus camera (Remidio, Bangalore, India)
19.5 Technology Assessment
Bak etal. [11] compared the RNFL defect measurements obtained from red-free fundus photography and optical coherence tomography (OCT)
en face imaging vis-à-vis the functional outcomes
in terms of mean and pattern standard deviation.
They reported that the en face RNFL defect
showed a higher correlation with the severity of
visual eld loss than the red-free RNFL defect.
Watanabe et al. [12] evaluated the accuracy of
glaucoma screening using fundus photography
combined with OCT.They found that the diagnostic accuracy of glaucoma screening signicantly increased when the OCT was added to the
fundus imaging.
19.6 Deep Learning-Based
Enhanced Optic Disc
Photography
This refers to the applications of articial intelligence (AI) techniques, specically deep learning
algorithms, to improve the quality and
interpretation of optic disc photographs. These
bd
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a
c
Fig. 19.5 Color fundus photograph and articial intelligence showing the segmentation of the optic disc boundary of
the right eye (a and b) and the left eye (c and d) (original photograph)
algorithms are trained on large datasets of annotated images to learn patterns and features that
aid in image enhancement, segmentation, and
analysis. These algorithms can extract features
from images and perform complex tasks, such as
enhancing image quality, sharpness, contrast, and
clarity without relying on explicit instructions,
and identify and correct common image artifacts,
such as noise, blurriness, and uneven illumination. These can be trained to automatically segment the optic disc region and accurately
delineate the borders, enabling precise measurements (Fig.19.5).
Over the years, optic disc image analysis has
witnessed signicant advancements (Table19.1),
beginning with early studies in the early 2000s
involving regression analysis and machine learning techniques. Subsequent developments focused
on applying AI frameworks for optic disc segmentation, enabling accurate estimation of parameters
such as vertical cup-to-disc ratio (VCDR) and
RNFL analysis. More recently, deep learning
algorithms have been employed for automated
abnormality detection, enabling the identication
of glaucoma-related features and providing valuable insights for clinical decision-making.
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