Content uploaded by Helena Prior Filipe
Author content
All content in this area was uploaded by Helena Prior Filipe on Aug 24, 2016
Content may be subject to copyright.
Filipe HP et al. UBM and AS-OCT in the diagnosis of glaucoma.
VISION PAN-AMERICAN – THE PAN-AMERICAN JOURNAL OF OPHTHALMOLOGY
Ultrasound biomicroscopy and
anterior segment optical coherence
tomography in the diagnosis and
management of glaucoma
Abstract
We aimed to summarize the applications,
strengths and weaknesses of two anterior segment
imaging modalities: the ultrasound biomicroscopy
(UBM) and the anterior segment optical coherence
tomography (AS-OCT) in the diagnosis and surgical
management of glaucoma.
This narrative review was based on our clinical
experience with these technologies supported
on scientific literature review through Medline
via PubMed®. The syntax used in the search was
“Glaucoma AND Anterior Chamber Angle AND
Ultrasound Biomicroscopy OR UBM AND Anterior
Segment Optical Coherence Tomography OR AS-
OCT”. Publications were selected based on relevance
and no redundancy, and authorship from 2007-2014.
Additionally, UBM and AS-OCT images were
selected from two of the authors’ personal archives
to illustrate prevalent glaucoma findings and post-
operatory using both technologies.
AS-OC T and UBM share overlapping characteristics
and are both useful in glaucoma diagnosis and post-
operative assessment. However, particular technical
features of each will direct the best application to
clarify specific glaucoma etiologies, to guide in the
most effective management and to explain glaucoma
surgical outcomes.
Key Words: Glaucoma, Anterior Chamber Angle;
Ultrasound Biomicroscopy; UBM; Anterior Segment
Optical Coherence Tomography; AS-OCT
Introduction
Detailed evaluation of anterior segment
structures is an integral part of ophthalmic
examination, particularly in patients with glaucoma.
Optical biomicroscopy and gonioscopy have been
classically used to assess anterior segment and
anterior chamber angle structures, and how they
relate to one another.
The innovative development of anterior segment
imaging has allowed physicians to visualize anterior
segment, angle structures, and aspects relevant to
diagnosis and management of glaucoma, which
could not be assessed by conventional techniques.
We aimed to summarize the applications,
strengths and weaknesses of two anterior segment-
imaging modalities: ultrasound biomicroscopy
(UBM) and anterior segment optical coherence
tomography (AS-OCT). This narrative review
was based on our clinical experience with these
technologies supported on scientific literature
review through Medline via PubMed® to support
our findings in practice setting. The syntax used in
the search was “Glaucoma AND Anterior Chamber
Angle AND Ultrasound Biomicroscopy OR UBM AND
Anterior Segment Optical Coherence Tomography
OR AS-OCT”. Publications were selected based on
relevance and no redundancy, and authorship from
2007-2014.
UBM and AS-OCT images were obtained from an
image library from the priv ate practice of the first and
second authors (HPF and MC) to illustrate prevalent
glaucoma findings and post-operatory features with
both technologies. All images were re-identified
prior to being considered for this publication.
Additionally, images were enhanced (brightness,
contrast, resolution, and orientation) to improve its
didactic purposes using Adobe Photoshop™ version
CS 5.1 software.
Helena Prior Filipe1, 2, 3, Manuela Carvalho3, Maria da Luz Freitas 4,
Zélia Maria Corrêa5
1. Hospital of the Armed Forces. Department of Ophthalmology. Lisbon Portugal
2. ALM, Medical and Surgical Ophthalmology Clinic Lisbon, Portugal
3. Hospital of SAMS. Department of Ophthalmology. Lisbon, Portugal
4. Hospital of Arrábida, Department of Ophthalmology. Porto, Portugal
5. Department of Ophthalmology, University of Cincinnati College of Medi-
cine, Cincinnati, OH, USA
Corresponding author: Helena P Filipe, MD
Rua Sargento José Paulo dos Santos nº 8 1800-331 Lisboa, Portugal, UE
E-mail: hpriorfilipe@gmail.com
Phone: +351967061457
Funding: None
Proprietary/financial interes: None
Date of submission: 13/01/2016 Date of Approval: 21/04/2016
38
Vis. Pan-Am. 2016; 15(2): 37-42.
frequencies. Ultrasound waves travel well through
the iris and ciliary body pigment epithelia allowing
the acquisition of high-resolution images of
structures behind the iris and the ciliary body. The
same does not apply to light beams, which are
highly bsorbed by the pigmented posterior layer
of the iris preventing a good visualization of the
retroiridian structures , sometimes essential for an
accurate diagnosis.1-5
The first commercialized UBM machine
(Paradigm Medical Industries, Salt Lake Cit y, UT) with
a 50 MHz probe, offered anterior segment quadrant
images of 25 μm (axial) x 50 μm (transversal)
resolution. Presently, machines as OTI (Ophthalmic
Technologies, Toronto, Canada), VuMax II (Sonomed,
Inc., Lake Success, NY, USA) and New Reflex™
(Reichert® Ultrasound Biomicroscope, Reichert
Technologies, USA) allow the acquisition of a 180º
image in a single frame permitting a comprehensive
qualitative and quantitative appreciation of the
anterior chamber. More recently, ultrasound devices
using a 80-MHz probe (Iscience, Mountain View,
CA) can image the Schlemm’s canal and trabecular
meshwork. However, the higher frequencies used,
the less tissue penetration we obtain, the best
quality eye wall images and the worse for posterior
to the iris. The ultrasound transducer needs to be
immersed in a coupling medium, either by using an
eyecup or a disposable water-filled small cap fixed
to the hand piece allowing the examination in the
sitting position. The ultrasound beam reaches the
anterior segment structures with minimal obstacle
and the reflected echoes generate a bi-dimensional
image. Topical anesthesia and patient cooperation
are essential during examination.5-7
AS-OCT is based on low-coherence
interferometry, that consists on the emission
of one infrared laser light beam by a super
luminescent diode. This is then split in two sub-
beams: one is directed towards the biological sample
and the other one to a mirror on the reference arm
that must be mechanically scanned to get range
information. Analysis of the reflection delay from the
sub-beams as they travel through these structures
is called time-domain technology or TD-OCT.
The Visante OCT (Carl Zeiss Meditec, Inc, Dublin,
California) works through this technology with a
light source of approximately 1310 nm.
In spectral domain OCT (spectral Fourier-
domain or SD/FD-OCT), the combined light beams
are passed through a grating that breaks it into a
spectrum, which is recorded by the line camera.
Fourier analysis is applied to the spectrum to return
it to the spatial domain and form the OCT image.
Spectralis OCT (Heidelberg Engineering GmbH,
Heidelberg, Germany) is based on this technology
and works with a wavelength of 840 nm.
The swept-source OCT or SS-OCT was developed
from SD-OCT and allows a full 360º assessment of the
anterior chamber angle. It works with a frequenc y swept
light source of 1050 nm and a high speed detector to
capture the interference signal as a function of time,
instead of a spectrometer and camera as in spectral-
domain technology. The higher speed imaging avoids
shadowing artifac ts, enables a better tissue penetration
and consequently a better visualization of the anterior
chamber angle through the sclera. Through the use
of Fourier transformation, swept-source and spectral
domain-OCT work faster than TD-OCT because no
mechanical scanning is involved.1-4
AS-OCT provides a resolution, of 18 μm (axial)
x 60 μm (transversal) for time domain AS-OCT
Visante (TD OCT) and as high as 5 μm (axial) x 7 μm
(transversal) for spectral/Fourier domain devices
(SD/FD systems).2,8
The claimed advantage of AS-OCT is its non-
contact scanning method performed in the sitting
position, whereas UBM requires eye contact through
a coupling medium, many times requiring supine
position, topical anesthesia and significantly more
patient cooperation.1
I. Characterization of Anterior Segment
A. Angle Closure Glaucoma
Primary angle closure glaucoma is a
heterogeneous group of eye diseases caused by
a variety of mechanisms. It can be categorized
according to the mainly involved anterior segment
structure showing abnormalities related to size
or position or as a result of abnormal forces in the
posterior segment (Table 1).7,9
This mechanism customarily leads to iris
apposition to the trabecular meshwork and
subsequent increase in intraocular pressure.
High resolution images provided by AS-OCT and
especially UBM can unveil the structure involved in
the underlying mechanism and guide to the most
effective management approach.7,9
A.1. Primary Pupil Block
It is known that aqueous humor flow resistance
at the irido-lenticular contact increases the
We discuss the importance
of anterior segment imaging
in characterizing anterior
segment morphology in angle
closure glaucoma and trauma,
in understanding the effect
of lighting conditions and age
on anterior segment angle
and in secondary open angle
glaucoma. We summarize
aspects related to quantitative
imaging in glaucoma and
discuss the relevance of anterior
segment imaging in glaucoma
surgical outcomes assessment.
Technology and Technique
Since its development,
ultrasound biomicroscopy
(UBM) has played a dominant
role in objective imaging of
the anterior chamber angle
until anterior segment optical
coherence tomography (AS-
OCT) was introduced in 2003.1
Ultrasound biomicroscopy
(UBM) is based on the emission
of a high-frequency ultrasound
beam (35-80 MHz) enabling high-
resolution cross sectional images
of anterior segment. Ultrasounds
at 50 to 80 MHz have axial
resolutions of approximately 50
to 20 µm, whereas a frequency
of 10 MHz has a resolution of
approximately 150 µm. The
higher the frequency, the lower
the penetration depth, which
is about 4-3mm for higher
Figure 1. UBM composite showing occludable angle related to primary pupillary block. (Top left); plateau iris, the angled iris root
pushed forward against the trabecular meshwork by an anteriorly rotated ciliary body (Top right); a thickened lens and a flattened
iris displaying a Mount Vesuvius configuration associated with phacomorphic glaucoma. (Center left); AS-OCT illustrating a plateau
iris, imaging of the ciliary body and its influence on the anterior chamber angle are not seen in so much detail with AS-OCT (Center
right); UBM reveals conjunctival oedema, the uveal effusion (thickened ciliary body and anterior choroid) pushes forward the anterior
segment structures and determines angle closure (Bottom left); AS-OCT reveals supra-ciliary and supra-choroidal effusion pushing
forward the lens equator to flatten the irido-ciliary sulcus and the posterior chamber and cause angle closure. Note the difference
in range and resolution between the two technologies (Bottom center); AS-OCT shows extreme forward positioning of the anterior
segment structures, flat anterior chamber (athalamia), iris and lens contact with the corneal endothelium (Bottom right).
Filipe HP et al. UBM and AS-OCT in the diagnosis of glaucoma.
VISION PAN-AMERICAN – THE PAN-AMERICAN JOURNAL OF OPHTHALMOLOGY
pressure in the posterior chamber, widens
its area and produces an anterior iris bowing
leading to angle closure (Figure 1. Top left).7
UBM and AS-OCT confirm diagnosis and
document pressure balance restoration between
both anterior and posterior chambers after laser
peripheral iridotomy (LPI). Anterior segment
imaging can also explain the reasons whereby
this procedure is unsuccessful in some angle
closure situations such as incomplete LPI,
goniosynechiae and plateau iris syndrome.
Iris-trabecular apposition disclosed by
gonioscopy, UBM or AS-OCT does not necessarily
imply an intraocular pressure increase. Iris-
trabecular meshwork contact may be intermittent
or relatively short (less than 360o and or not
reaching the Schwalbe’s line) and the uveoscleral
route may represent approximately 10% of
drainage. Usually, mydriasis is associated with an
iris root aqueous volume decrease. In eyes prone
to angle-closure glaucoma, this phenomenon
can be compromised and even be a precipitating
factor.10-13 Considering the latter two aspects,
it is possible to infer the relevance of assessing
iris thickness and standardizing test lighting
conditions when using UBM or AS-OCT for
quantitative assessments.
A.2. Plateau Iris
UBM and AS-OCT typically show a thick, flat or
slightly anterior bowed iris, which abruptly ascends
after its insertion on the ciliary body’s anterior
surface assuming a “square root” appearance.
Indentation gonioscopy or UBM may reveal the
double-hump sign. The most peripheral hump
drapes over the rigid, anteriorly positioned ciliary
body, and the central rests over a long extension
on the anterior lens surface. A modified dynamic
gonioscopy procedure using AS-OCT allowed
the conclusion that anterior chamber angle
(ACA) amplitude was significantly higher after
indentation and that indirect signs were reliable to
suggest a plateau iris. Anterior rotation of the ciliary
body, best observed with UBM, is associated with
anterior positioning of the iris dilator’s anchorage
point and determines: iridociliary sulcus narrowing,
iris apposition to the trabecular meshwork and
angle closure. The farther away the iris dilator “joint”
from the scleral spur, the lower the probability of
angle closure. The central depth of the anterior
chamber is usually normal (Figure 1. Top right and
center right). 11, 14, 15
UBM and AS-OCT images can also be useful
to assess the effect of argon laser peripheral
iridoplasty on the ACA allowing objective anterior
segment measurements.
A.3. Phacomorphic Glaucoma
UBM and AS-OCT can confirm the presence
of an intumescent lens pushing forward the
iris, which can assume a “Mount Vesuvius
configuration”, and the ciliary body determining
iris/trabecular meshwork apposition. An increased
lens vault elevates the probability of progression
to angle-closure glaucoma, regardless of lens
thickness and location (Figure 1. Center left).16
A.4. Uveal Effusion/Malignant Glaucoma
Very small eyes, especially nanophthalmos, are prone to angle
closure due to their dimensions, unsuccessful regulation mechanisms,
and vitreous resistance to fluid flow. All these concur to create expansion
of choroidal volume and consequently high posterior lenticular pressure
promotes extreme forward positioning of anterior segment structures.
This mechanism leads to maximal resistance to aqueous humor flow
and intraocular pressure rise. UBM and AS-OCT document lens, iris and
vitreous anteriorly positioned, absence of posterior chamber, markedly
reduced anterior chamber depth until athalamia, and uveal effusion
(Figure 1. Bottom left, center and right). 11,16
A5. Other Causes of Angle Closure
Primary or secondary cystic or solid lesions of the iris and/or
ciliary body, goniosynechia, cyclitic membrane, vitreous hernia, or
post-vitreoretinal surgery using vitreous tamponade (silicone oil or
gas) may trigger partial or intermittent angle closure that can be
documented by UBM and AS-OCT (Figure 2).
A6. Other structural aspects
A6.1.Trauma
When evaluating an eye with a history of trauma, UBM is particularly
important if optical media are not transparent (hyphema or hypopyon)
and can reveal angle recession or cyclodialysis, potentially explaining
respectively intraocular pressure increase or decrease after the injury
Site of aqueous
humor obstruction Angle closure glaucoma
Iris Primary Pupil Block
Ciliary Body Plateau Iris
Lens Phacomorphic Glaucoma
Suprachoroidal Fluid Uveal Effusion / Aqueous Misdirection
Table 1. Classification of angle closure glaucoma according to Ritch. The four anatomic sites where aqueous flow obstruction may occur.
Figure 2. Left UBM images reveal secondary angle closure due to the presence of a single or multiple retro iridian cysts. Note the pseudo
plateau configuration in the down left image. Top right UBM image illustrates an iris tumor. Down right UBM image shows a gonio-
synechia (black arrow)
40
Vis. Pan-Am. 2016; 15(2): 37-42.
(Figure 3). UBM might be problematic to
use in recent perforating trauma or early
post-operative period. As a noncontact
technology, AS-OCT is potentially a better
option to avoid potential complications
related to wound healing or intraocular
infection.10
A6.2. Effect of Lighting Conditions
and Age
Lighting conditions may cause relevant
variation in the anterior segment topography.
Additionally, anterior movement of the lens
has been estimated to be approximately 20
μm/year with increasing age. This is associated
with a progressively increasing intumescence
of the lens, reduced anterior chamber
depth and ACA narrowing. The mechanism
is clinically more significant in eyes with
anatomical predisposition to angle closure,
such as in hyperopia, nanophthalmos, plateau
iris, and others.16, 17
B. Secondary Open-Angle Glaucoma
The diagnostic triad of pigmentary
glaucoma consisting of Krukenberg spindle,
radial transillumination defects and trabecular
meshwork pigment is caused by pigment
dispersion due to mechanical friction bet ween
posterior iris surface and zonule. Both UBM
and AS-OCT may reveal a back bowing iris
touching zonular filaments, creating a “reverse
pupillary block ”. In these cases, laser peripheral
iridotomy, flattens the iris, confirming
balanced pressure gradient between anterior
and posterior chambers (Figure 4).18
II. Quantitative Imaging
in Glaucoma
Anterior segment measurements have attained
increased objectivity, accuracy and reproducibility
since Pavlin’s first biometric descriptors were
published. The concept rapidly extended to AS-
OCT. The scleral spur is the landmark from which
many measurement parameters are estimated. After
its manual localization and application with a semi-
automated software system, the anterior chamber
angle can be quantitatively characterized in a fast
and reproducible manner. However, identifying
the scleral spur in angle closure cases may be
challenging, especially in the upper and lower
quadrants. UBM can be a better option in such
cases, due to the ultrasound waves ability to travel
through pigment bearing tissue and better reveal
retro-iridial structures. Research is under way to
find one or a set of effective biometric descriptors
to accurately diagnose angle occlusion and predict
angle closure glaucoma probability.1,6, 7,12,19,20
III. Assessment of Glaucoma
Surgery Outcomes
UBM and AS-OC T substantially complement
slit lamp biomicroscopy in assessing filtering blebs’
features. Yamamoto has proposed a classification
system correlating filtering bleb ultrasound
characteristics and bleb function. The internal
echographic structure of the filtering bleb and the
presence of an intra-scleral route have shown good
correlation with intraocular pressure control (type
L bleb). Based on AS-OCT, Labbé et al. defined four
types of filtering blebs according to its morphology
and internal reflectivity: diffuse, microcystic, flattened
and encapsulated. Good intraocular pressure control
has been shown on diffuse and microcystic filtering
blebs similar to the findings illustrated in Figure 5.21-24
Correlation between in vivo confocal microscopy
findings and filtering bleb reflectivity (AS-OCT)
with filtering glaucoma surgery outcomes, has
suggested that heterogeneous, lower reflective
supra-scleral tissues match with loose connective
tissue, where gaps and high fluid content abound
thus documenting a functional bleb.25
UBM and AS-OCT can also assess several other
glaucoma surgery-related aspects such as the
patency of the glaucoma filtering surgery internal
ostium; the effect of LPI on anterior chamber
morphology; the trabeculo-Descemet window
integrity and thickness; the presence of intra-scleral
route; the intra- and supra-scleral “lake” dimension;
the fluid in supra-choroidal space; the patency,
route and relation of aqueous drainage devices
with neighboring structures and the cause for
non-functioning glaucoma filtering surgery (Figure
5).26 More recently, very high frequency probes (80
MHz) enabled the identification of Schlemm’s canal,
Figure 3. UBM image illustrates post-traumatic anterior chamber angle recession without complete separa-
tion of the iris and ciliary body (cyclodyalisis) but associated with supra-ciliary oedema.
Filipe HP et al. UBM and AS-OCT in the diagnosis of glaucoma.
VISION PAN-AMERICAN – THE PAN-AMERICAN JOURNAL OF OPHTHALMOLOGY
confirming it’s opening after surgical viscocanaloplasty.
IV. Ultrasound Cyclocoagulation
High Intensity Focused Ultrasound (HIFU) is already
being used to treat refractory glaucoma. Ultrasound waves
are transmitted through a circular microdevice with six
piezoelectric transducers that focus ultrasound emission
on the ciliary body, promoting precise cyclocoagulation.
Evidence shows the efficacy of this therapy in achieving
intraocular pressure control and improved tolerability
when compared to other cyclodestructive techniques.
Morphological alterations produced by circular ultrasound
cyclocoagulation can be evaluated using UBM.27
UBM or AS-OCT enable anterior chamber width (ACW)
measurements to select the best ring diameter for direct use
on the ciliary body.28
Concluding Comments
Our clinical experience shows that AS-OCT and UBM
share overlapping features and both are useful in glaucoma
diagnosis and surgical assessment. This is in accordance to
the literature reviewed. However, specific technical features
of each technology such as axial and transversal resolution,
visualization of retro-iridial structures, detailed appreciation of
tissue microstructure and an easy faster non contact imaging
acquisition tend to determine the choice of technology used
according to the information the examiner is specifically
looking for (Table 2). Examiner and patient biases should also
be recognized and considered when selecting the imaging
method to be employed. User biases include examiner
experience, degree of comfort using a certain technology and
availability of that technology. Patient biases include comfort,
cooperation and other occupational circumstances.
Both technologies provide real time high resolution cross
sectional images of the anterior segment including the ACA
upon which biometric descriptors can be used for quantitative
characterization, diagnosis, and surgical management of
glaucoma. Best advantage of AS-OCT over UBM is that it is a
friendly user, reproducible and swift noncontact technology.
UBM classically requires a supine position, immersion, time,
patient collaboration and a skilled operator. On the other hand,
UBM’s major advantage lies on the ultrasound beam’s ability
Figure 4. AS-OCT shows a back bowing iris that causes zonular fibers friction and a reverse pupil block associated with pigmentary glaucoma (Left). AS-OCT image illustrates
the iris flattening after laser periphery iridotomy and reverse pupil block resolution (Right).
Figure 5. Post-operative findings after non-penetrating deep sclerectomy (NPDS) evaluated by UBM
(Left column) and AS-OCT (Right column). Polycystic blebs feature low reflective supra-scleral tissues
with multiple coalescent low reflective spaces (First row). Diffuse filtering blebs present low reflective
supra-scleral tissues, intra-scleral lake and a trabeculo-Descemet window (Second row). Flattened
filtering blebs feature high reflective supra-scleral tissues, intra-scleral lake and route and a thin
trabeculo-Descemet window (Third row). Encapsulated filtering blebs present high reflective supra-
scleral tissue and a contained lake (Forth row).
42
Vis. Pan-Am. 2016; 15(2): 37-42.
to travel through iris pigment epithelium
allowing a good view of retro-iridial structures
as the ciliary body, posterior chamber, zonule,
anterior vitreous and lens posterior capsule.
UBM can also provide high resolution imaging
through opaque media.
Despite these high-resolution techniques
with digital capabilities that enhance our ability
to evaluate and share acquired dynamic images
of anterior segment, we can still wonder about
the prevailing technology in glaucoma imaging.
Based on our experience and literature review, we
are certain that both complement each other.
References
1. Ursea R, Silverman RH. Anterior Segment Imaging
for assessment of Glaucoma. Expert Rev Ophthalmol.
2010;5(1):59-74.
2. Schuman JS. Spectral Domain Optical Coeherence
Tomography for Glaucoma (An AOS thesis) Trans Am
Ophthalmol Soc. 2008;106:426-58.
3. Huang D, Swanson EA, Lin CP, Schuman JS, Stinson
WG, Chang W, Hee MR, Flotte T, Gregory K,
Puliafito CA et al. Optical coherence tomography. Sci-
ence.1991:254(5035):1178-81.
4. Sharma R, Sharma A, Arora T, Sharma S, Sobti A,
Jha B, Chaturvedi N, Dada T. Diagnostic and surgical
techniques Application of anterior segment optical
coherence tomography in glaucoma. Surv Ophthalmol.
2014;59(3):311-27.
5. Quek DT, Nongpiur ME, Perera SA, Aung T. Angle
imaging: Advances and challenges. Indian J Ophthalmol.
2011; 59(Suppl): S69–75.
6. Pavlin CJ, Harasiewicz K, Sherar MD, Foster FS. Clinical
use of ultrasound biomicroscopy. Ophthalmology. 1991;
98: 287–95.
7. Ishikawa H, Schuman J. Anterior Segment Imaging:
ultrasound biomicroscopy. Ophthalmol Clin North Am.
2004; 17(1): 7-20.
8. Salim S. The Role of Anterior Segment Optical
Coherence Tomography in Glaucoma. J Ophthalmol.
2012;2012:476801.
9. Ritch R, Liebmann J, Tello C. A construct for
understanding angle-closure glaucoma: the role of
UBM and AS-OCT UBM AS- OCT
Performance Advantages
Both technologies
- Provide evidence
of contributing
mechanisms and
principal structures
causing angle-
closure glaucoma
to decide the best
effective treatment
- Characterize
quantitatively
anterior segment
using measurement
parameters as
valuable screening,
diagnostic
and treatment
assessment tools
- Illustrate how the
complex ciliary
body/ iris– ACA
changes with age,
accommodative and
light stimuli
- Assess glaucoma
ltering surgery
outcomes
- Provides high-resolution
cross sectional images of
anterior segment and ACA
including structures behind
the iris such as the ciliary
body, zonule, pars plana,
anterior lens face, lens
equator and anterior vitreous
- Enables visualization
of morphology and
topography changes of
ACA structures associated
with lighting conditions,
drugs, indentation
gonioscopy and age
- Provides high-
resolution cross
sectional images of
anterior segment
to the iris-lens
diaphragm
- Is easy to operate
-Does not require
much collaboration
-Offers fast
acquisition
-Allows exact
knowledge of image
location
-Can be used in
early post-operative
period and ocular
trauma
Disadvantages
- Requires immersion
technique, although a
saline lled eye cap can be
adapted to the probe;
- May cause
Discomfort
Abrasion and infection
Potential anterior segment
deformation
Inadvertent indentation
- Is time-consuming
- Requires
Trained operator
Classically a more supine
position
Collaborative patient
-Does not provide
much detail of
structures posterior
to the iris
Table 2. Advantages and disadvantages of Ultrasound Biomicroscopy (UBM) and Anterior Segment OCT (AS-OCT).
ultrasound biomicroscopy. Ophthalmol Clin North Am.
1995;8(2): 281–93.
10. Liebmann JM, Ritch R, Esaki K. Ultrasound Biomicroscopy,
Ophthalmol Clin North Am.1998;11(3):421-33.
11. Quigley H. Angle closure glaucoma- simple answers to
complex mechanisms: LXVI Edward Jackson Memorial
Lecture. Am J Ophthalmol. 2009;148(5):657-69.
12. Friedman DS, He M. Anterior chamber angle assessment
techniques. Surv Ophthalmol. 2008; 53(3):250-73.
13. Wang BS, Narayanaswamy A, Amerasinghe N, Zheng C, He
M, Chan YH, Nongpiur ME, Friedman DS, Aung T. Increased
Iris thickness and association with primary angle closure
glaucoma. Br. J. Ophthalmol. 2011;95(1):46-50.
14. Matonti F, Chazalon E, Trichet E, Khaled el S, Denis D,
Hoffart L. Dynamic Gonioscopy Using Optical Coherence
Tomography. Ophthalmic Surg Lasers Imaging. 2012;43(6
Suppl):S90-6.
15. Cronemberger S. Diniz Filho A, Calixto N. La importancia
de la biomicroscopía ultrasónica en el diagnóstico de la con-
figuración del iris en meseta. Vis Pan-Am: 2014:13(4):101-5.
16. Nongpiur ME, Ku JY, Aung T. Angle closure glaucoma: a
mechanistic review. Curr Opin Ophthalmol. 2011;22(2):96-101.
17. Baikoff G. Safety Criteria for phakic intraocular lens
implantation based on anterior segment optical coherence
tomography biometry, in Steinert. RF, Huang D. Anterior
Segment Optical Coherence Tomography. Chap 11. Slack inc.
Thorofare NJ 2008.
18. Mora P, Sangermani C, Ghirardini S, Carta A, Ungaro
N, Gandolfi SA. Ultrasound biomicroscopy and iris pig-
ment dispersion: a case-control study. Br J Ophthalmol.
2010;94(4):428-32.
19. Li H, Leung CK, Cheung CY, Wong L, Pang CP, Weinreb
RN, Lam DS. Repeatability and reproducibility of anterior
chamber angle measurement with anterior segment optical
coherence tomography. Br J Ophthalmol. 2007;91(11):1490-2.
20. Friedman DS, Foster PJ, Aung T, He M. Angle closure and
angle-closure glaucoma: what we are doing now and what
we will be doing in the future. Clin Experiment Ophthalmol.
2012;40(4):381-7.
21. Yamamoto T, Sakuma T, Kitazawa Y. An ultrasound
biomicroscopic study of filtering blebs after mitomycin C
trabeculectomy. Ophthalmology. 1995;102(12):1770-6.
22. Marcon IM, Mello PAA, Corrêa ZMS, Marcon AS. Cor-
relação entre os achados à biomicroscopia ultrassônica de
bolhas filtrantes, com ou sem mitomicina C, e a pressão
intra-ocular. Arq Bras Oftalmol. 2000; 63: 65-70.
23. Labbé A, Hamard P, Iordanidou V, Dupont-Monod S,
Baudouin C. Utility of the Visante OCT in the follow-up of
glaucoma surgery. J Fr Ophtalmol. 2007;30(3):225-31.
24. Baudouin C, Labbe A, El Maftouhi A, Hamard P. Application
of anterior segment OCT to the study of glaucoma. J Fr
Ophtalmol. 2008, 31(6 Pt 2):2S5-9.
25. Messmer EM, Zapp, DM, Mackert MJ, Thiel M, Kampik A. In
vivo confocal microscopy of filtering blebs after trabeculec-
tomy. Arch Ophthalmol. 2006;124:1095-103.
26. Ng WT, Morgan W. Mechanisms and treatment of primary
angle closure: a review. Clin Exp Ophthalmol. 2012; 40:
e218–28.
27. Aptel F, Charrel T, Lafon C, Romano F, Chapelon JY,
Blumen-Ohana E, Nordmann JP, Denis P. Miniaturized
High-Intensity Focused Ultrasound Device in Patients with
Glaucoma: A Clinical Pilot Study. Invest Ophthalmol Vis Sci.
2011;52(12):8747–53.
28. Smith SD, Singh K, Lin SC, Chen PP, Chen TC, Francis BA,
Jampel HD. Evaluation of the Anterior Chamber Angle in
Glaucoma. Ophthalmology. 2013;120(10):1985-97.
