Stratus optical coherence tomography study of filtering blebs after primary trabeculectomy with a fornix-based conjunctival flap.
ABSTRACT To investigate the relationship between filtering bleb function and Stratus optical coherence tomography (OCT) images.
We studied 72 eyes of 65 consecutive patients who had a fornix-based conjunctival flap in primary trabeculectomy with mitomycin C (MMC). Filtering blebs with various types of glaucoma were examined using Stratus OCT. Success rates were defined as intraocular pressure (IOP) < or = 15 mmHg and IOP reduction > or = 25% without medication or additional surgery. Success rates among classified groups were compared using Kaplan-Meier survival curves and the log-rank test.
Blebs were classified into three different categories on the basis of the following Stratus OCT patterns: cystoid type (multiple cysts inside the bleb; 17 eyes), diffuse type (low to high reflective areas that were mixed inside the bleb; 31 eyes) and layer type (medium to high reflective layer inside the bleb; 24 eyes). Success rates in the cystoid-, diffuse- and layer-type blebs were 94%, 97% and 75% (P = 0.02), respectively.
In trabeculectomy with MMC and a fornix-based conjunctival flap, there is a significant association between the success rates and the postoperative Stratus OCT findings of filtering blebs.
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ABSTRACT: Evaluation of patients after trabeculectomy can be aided by the use of anterior segment imaging. Two commonly used forms of imaging are ultrasound biomicroscopy (UBM) and optical coherence tomography (OCT). Both modalities can be used to assess bleb morphology and how it affects treatment outcome, measure anterior chamber biometry, identify the presence of supraciliochoroidal fluid, cyclodialysis clefts and malignant glaucoma, and evaluate treatment modalities after trabeculectomy such as in laser suture lysis and needling. OCT, with its finer resolution, is able to view the bleb wall anatomy in detail and because of its non-contact nature can examine the eye sooner after trabeculectomy. UBM, on the other hand, is superior for the visualization of deeper structures such as the ciliary body and posterior chamber essential to identify malignant glaucoma.Seminars in ophthalmology 09/2012; 27(5-6):160-4. · 1.09 Impact Factor
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ABSTRACT: To provide a qualitative and quantitative analysis of filtering blebs with optical coherence tomography (OCT) in patients after primary trabeculectomy. Evaluation of diagnostic technology. We retrospectively studied 20 eyes of 20 patients who had a fornix-based flap in primary trabeculectomy: 14 with mitomycin C (MMC) and 6 without MMC. Filtering blebs were examined using 2 types of OCTs working at a wavelength of 840 and 1310 nm. In this study, we analyzed both the OCT morphologic pattern and the internal structures of blebs, including bleb wall thickness, scleral flap thickness, and the route under the scleral flap, and quantified the reflectivity of the intrableb area. Blebs were classified according to the Hirooka scheme in 3 OCT morphologic patterns: cystoid, diffuse, and layer type. The MMC was associated with the surgical success (100%). A significant association was found between good functionality and cystoid type with both devices: 840-nm OCT (p = 0.02) and 1310-nm OCT (p = 0.04). A significant difference in morphologic patterns was found using the 2 OCTs. There were no significant differences between successful and unsuccessful filtering surgery for intrableb structures. The reflectivity of filtering blebs correlated very well to the postoperative intraocular pressure (IOP; R(2) = 0.90; p < 0.001) and to the reduction of IOP (R(2) = 0.58; p = 0.001). Our method to quantify the reflectivity showed a significant degree of intergrader consensus (intraclass correlation coefficient = 0.99; p < 0.001). Although 840-nm OCT was not developed to assess the anterior segment, it may be considered a useful tool to evaluate the functionality of blebs in the postoperative period.Canadian Journal of Ophthalmology 04/2014; 49(2):210-6. · 1.30 Impact Factor
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ABSTRACT: Die internen Strukturen von Sickerkissen in verschiedenen postoperativen Phasen konnten sowohl mit dem Vorderabschnitts-OCT als auch in-vivo konfokalmikroskopisch am Patienten dargestellt und analysiert werden. Hierbei konnte bei beiden Verfahren festgestellt werden, dass bestimmte Parameter prognostische Relevanz für die Funktion des Sickerkissens haben. Eine gute Sickerkissenfunktion korrelierte in der IVKM frühpostoperativ mit einem geringen Rundzellinfiltrat und einem geringem Gefäßdurchmesser und spät-postoperativ mit einer hohen Zahl epithelialer Zysten. Bei der optischen Kohärenztomographie ließ sich frühpostoperativ ein signifikanter Zusammenhang zwischen der Anwesenheit supraskleraler Flüssigkeitsräume sowie dem Nachweis des „striping“- Phänomens und einer guten Sickerkissen-Funktion nachweisen. Eine Kombination dieser Verfahren mit dem klinischen Befund können in Zukunft dazu beitragen, die unterschiedlichen postoperativen Ergebnisse nach Trabekulektomie auf histopathologischer Ebene besser zu verstehen. Dadurch könnte das chirurgische Vorgehen sowie die adjuvante Medikamentengabe optimiert werden, das postoperative Sickerkissen-Management erleichtert werden und somit gegebenenfalls rechtzeitig interveniert werden. Somit könnte die Erfolgsrate nach filtrierenden Glaukomoperationen zukünftig gesteigert werden. The internal structures of filtering blebs in different postoperative phase could be detected and analyzed with the Visante-OCT and in vivo confocal microscopy. Both methods could show that certain parameters have prognostic relevance for the function of the blebs. A good function of the bleb correlated early postoperatively with a small roundcell infiltrate and a small vessel diameter, and late postoperatively with a high number of epithelial cysts in in-vivo microscopy. Optical coherence tomography showed a significant correlation between the presence of suprascleral fluid spaces and evidence of the "striping"-phenomenon and a good bleb function early postoperativly. A combination of these methods to the clinical findings may contribute to better postoperative results. Thus, the surgical procedure and adjuvant medication could be optimized and the postoperative bleb management could become easier. This would increase the success rate of glaucoma filtering operations.
method of choice in the surgical treat-
ment of patients with glaucoma (Cairns
depends mainly on the function of the
filtering bleb. For long-term success,
the critical factors include not only
surgical technique but also age, type of
glaucoma (Mills 1981), prior failed
filtering surgery and long-term use of
(Broadway et al. 1994). However, the
reason for unsuccessful filtration is
often unclear. Frequently, failure is
caused by conjunctival scarring and
obliteration of the bleb as opposed to
internal occlusion of the ostomy. In
order to correlate the clinical and func-
tional aspects, many authors have
investigated the morphological crite-
ria of the bleb (Vesti 1993; Cantor
et al. 2003; Wells et al. 2004). However,
in some cases, there is no correlation
between the bleb appearance or shape
Clinically, it is not easy to study the
reasons for failure related to bleb scar-
ringand the histological
within the bleb tissue. Unfortunately,
this makes it difficult to undertake
appropriate therapeutic interventions,
because therapy can only be attempted
based on identification of the cause of
Intrableb imaging is usually per-
formed by ultrasound biomicroscopy
(UBM), a technology that has been
developed specifically for the purpose
of studying the anterior segment of
the eye (Yamamoto et al. 1995; Chiou
et al. 1998; Marchini et al. 2001; Rot-
ers et al. 2002; Zhou et al. 2006).
Optical coherence tomography (OCT)
is a recently developed, non-invasive,
non-contact technique for imaging of
the layered structure of the retina
Stratus optical coherence
tomography study of filtering
blebs after primary
trabeculectomy with a
fornix-based conjunctival flap
Kazuyuki Hirooka, Mai Takagishi, Tetsuya Baba, Hirokazu
Takenaka and Fumio Shiraga
Department of Ophthalmology, Kagawa University Faculty of Medicine, Kagawa,
Purpose: To investigate the relationship between filtering bleb function and
Stratus optical coherence tomography (OCT) images.
Methods: We studied 72 eyes of 65 consecutive patients who had a fornix-
based conjunctival flap in primary trabeculectomy with mitomycin C (MMC).
Filtering blebs with various types of glaucoma were examined using Stratus
OCT. Success rates were defined as intraocular pressure (IOP) £ 15 mmHg
and IOP reduction ‡ 25% without medication or additional surgery. Success
rates among classified groups were compared using Kaplan–Meier survival
curves and the log-rank test.
Results: Blebs were classified into three different categories on the basis of the
following Stratus OCT patterns: cystoid type (multiple cysts inside the bleb;
17 eyes), diffuse type (low to high reflective areas that were mixed inside the
bleb; 31 eyes) and layer type (medium to high reflective layer inside the bleb;
24 eyes). Success rates in the cystoid-, diffuse- and layer-type blebs were
94%, 97% and 75% (P = 0.02), respectively.
Conclusion: In trabeculectomy with MMC and a fornix-based conjunctival
flap, there is a significant association between the success rates and the postop-
erative Stratus OCT findings of filtering blebs.
Key words: bleb – glaucoma – optical coherence tomography – trabeculectomy
Acta Ophthalmol. 2010: 88: 60–64
ª 2008 The Authors
Journal compilation ª 2008 Acta Ophthalmol
Acta Ophthalmologica 2010
(Huang et al. 1991; Hee et al. 1995).
Anterior segment imaging has been
reported by several investigators who
used either the prototype OCT system
(Izatt et al. 1994; Hoerauf et al. 2000;
Kalev-Landoy et al. 2007) or the reti-
nal OCT scanner (Muscat et al. 2002).
The majority of these studies focused
on corneal imaging. OCT has been
used to examine filtering blebs after
(Nozaki et al. 2002). Babighian et al.
(2006) reported Stratus OCT images
of filtering bleb after trabeculectomy.
Savini et al. (2005) reported recently
that filtering blebs could be classified
into three different categories accord-
ing to their OCT pattern. However, in
observed, no correlation was noted
between their OCT bleb pattern and
IOP (Savini et al. 2005). Anterior-seg-
ment OCT (AS-OCT) has also been
(Singh et al. 2007). In the current
study, we used Stratus OCT (OCT 3;
USA) to examine filtering blebs after
primary trabeculectomy with a fornix-
based conjunctival flap in order to
investigate the relationship between
bleb function and its Stratus OCT
Materials and Methods
We evaluated 72 filtering blebs of 65
patients who had previously under-
gone trabeculectomy between October
2003 and October 2005, and who were
followed up at the Kagawa University
Hospital, Japan. Patients ranged in
age from 32 to 86 years [mean ±
11.2 years]. There were 33 male and
32 female patients. All eligible partici-
pants received a detailed explanation
before both the trabeculectomy and
the Stratus OCT. In this study, we did
not use slit-lamp-adapted OCT (SL-
OCT). All patients signed an informed
consent form, in accordance with the
Declaration of Helsinki. Twenty-three
eyes with primary open-angle glau-
coma, 10 with normal-tension glau-
coma, four with primary angle-closure
glaucoma, 27 with secondary glau-
coma caused by uveitis and eight with
included in the study.
(SD) 67.0 ±
All patients underwent a standard
ophthalmological examination includ-
ing slit-lamp examination, Goldmann
applanation tonometry and binocular
fundus examination on day 1, weeks 1
and 2, months 1, 2, 3, 6 and 12 post-
operatively, and as necessary.
one of the two surgeons (K.H., T.B.).
lidocaine 2%, the eye was prepared
and draped. A corneal traction suture
was placed with a 6-0 silk and the
dissected. After the formation of a
one-half-thickness scleral flap (approx-
imately4 · 4 mm),
(MMC) was applied with a sponge
containing 0.4 mg⁄ml MMC solution
placed under the conjunctival flap for
removed, the area covered by the
sponge was irrigated copiously with
250 ml of physiological saline. At the
edge of the corneoscleral bed, a block
of clear cornea and trabecular mesh-
work tissue was removed and periph-
eral iridectomy was performed. The
scleral flap was sutured with six or
seven 10-0 nylon sutures. The con-
junctiva was closed using 10-0 nylon
sutures at the edges of the incision,
with one or more horizontal mattress
sutures placed centrally. The anterior
chamber was reformed with balanced
salt solution and the wound checked
for leaks. A corticosteroid⁄antibiotic
ointment was instilled, followed by a
sterile eye patch and shield. Postoper-
atively, all patients were treated with
daily) and an antibiotic for 8–12
OCT procedure and bleb examination
Stratus OCT examination was per-
formed 12 months after the surgery
and before any further glaucoma sur-
gery (including needling). The filtering
bleb was visualized on the video mon-
itor and the length of the scanning
line was between 5 mm and 7 mm
(Fig. 1). All scans were oriented hori-
zontally to the limbus and covered the
entire surface of the bleb, from the
nasal to the temporal edge. The same
examiner (M.T.) took 10 images of a
bleb. The images included five sections
horizontal to the limbus along with
five vertical sections nasal to the tem-
manually on the conjunctiva. Patients
were instructed to look downward
during the examination. Stratus OCT
images for each eye were stored on
the instrument’s hard drive. To ensure
consistency, a single researcher (K.H.)
who was masked toward the clinical
Fig. 1. The line acquisition protocol was used and the length of the scanning line was between
5 mm and 7 mm. The white line indicates the scanning line.
Acta Ophthalmologica 2010
features and IOP control analysed all
of the Stratus OCT images.
Bleb appearance was characterized
using a slit lamp. The Indiana Bleb
Appearance Grading Scale (IBAGS)
has been described previously (Cantor
et al. 2003). Three parameters are
scored: height of the bleb (H), with a
scale ranging from H0 (flat) to H4
(high); extent of the bleb (E), with a
scale ranging from E (< 1 hr) to E3
(> 4 hr); and vascularity of the bleb,
with a scale of V0 (avascular) to V4
For the purpose of this study, clinical
filtration success was defined in terms
of IOP. Surgical success was defined
as IOP £ 15 mmHg and IOP reduc-
medication. Eyes that required further
glaucoma surgery (including needling)
or glaucoma medication to lower IOP
were considered failures.
Statistical analysis was performed
using spss for Windows (SPSS Inc.,
Chicago, IL, USA). Kaplan–Meier
survival analysis and the log-rank test
were used to determine success rates.
A P-value of < 0.05 was considered
statistically significant. Data are pre-
sented as means ± SD.
Images were obtained in 72 blebs of
obtained easily in all eyes. The Stratus
OCT images of the inside of blebs
after trabeculectomy with a fornix-
based conjunctival flap could be clas-
sified into three categories. For each
patient, 10 bleb images were obtained;
the same category was found to be
present in each eye for all of the
blebs (17 eyes) showed multiple cysts
inside the bleb (Fig. 2A). Diffuse-
type blebs (31 eyes) showed low to
high reflective areas that were mixed
inside the bleb (Fig. 2B). Layer-type
blebs (24 eyes) were characterized by
a medium to high reflective layer
inside the bleb (Fig. 2C). In the cys-
toid-, diffuse- and layer-type blebs,
the success rates were 94%, 97% and
75% (P = 0.02), respectively (Fig. 3).
There were bleb failures for one eye
for both cystoid- and diffuse-type
blebs, and six bleb failures in the
Fig. 2. Bleb imaging after trabeculectomy with a fornix-based conjunctival flap. (A) Cystoid-type bleb.
Optical coherence tomography (OCT) shows the filtering bleb with multiple cysts inside the bleb. (B) Dif-
fuse-type bleb.OCTshowsthefilteringblebwith lowto highreflective areasthat were mixedinside thebleb.
(C) Layer-type bleb. OCT shows the filtering bleb with a medium to high reflective layerinside the bleb.
Probability of success
Fig. 3. Results of Kaplan–Meier survival analysis with success defined as intraocular pressure (IOP)
£ 15 mmHg and IOP reduction ‡ 25% without medication or additional surgery. Success rates in the
cystoid-, diffuse- and layer-type blebs were 94%, 97% and 75% (P = 0.02) at 12 months, respectively.
Acta Ophthalmologica 2010
layer-type bleb group. At 1, 2, 3, 6
(two eyes) or 7 months after surgery,
a total of six of these eyes required
needling. Two eyes had IOPs outside
the success criteria range at 6 and
encapsulated bleb developed in six
eyes. In five of these six encapsulated
presence of layer-type blebs.
There were no significant differences
related to glaucoma diagnosis and the
Stratus OCT images of the inside of
blebs (P = 0.15, v2test; Table 1). The
relation between bleb characteristic
and the Stratus OCT images of the
inside of blebs is shown in Table 2.
There was no significant difference
related to Stratus OCT images and
bleb height(P = 0.824,
extent (P = 0.754, v2test) or vascu-
larity (P = 0.666, v2test). Table 3
shows the relation between failure
bleb characteristic and Stratus OCT
The long-term success of trabeculec-
tomy is dependent mainly on the
development of a functioning filtering
bleb. Therefore, the formation and
maintenance of functioning blebs are
of primary importance. Because clini-
cal bleb evaluation is limited to super-
ficial tissue layers, important data
about bleb development
missed. When using UBM, the struc-
ture inside the filtering bleb can be
visualized clearly. In addition, features
of the UBM images have been shown
to have a strong association with fil-
tering bleb function when expressed as
the IOP control level (Yamamoto
et al. 1995).
AS-OCT was applied for the evalu-
ation of filtering blebs at a single
point in time within a widespread per-
iod after surgery (2 months to 16
years; Singh et al. 2007). In contrast,
all blebs except failures were imaged
at 12 months after the surgery in our
study. In a recent report by Savini
et al. (2005), OCT was used to study
filtering blebs in a limited number of
patients. The authors noted that the
blebs could be classified into three dif-
ferent categories according to their
OCT patterns. However, their OCT
those noted in the present study. In
Savini et al.’s study, data that could
have influenced the bleb appearance –
such as the site of the conjunctival
incision (fornix- or limbus-based) and
the Tenon’s capsule excision – were
not included. All of our patients
received trabeculectomy with a fornix-
based conjunctival flap, for which no
part of Tenon’s capsule was excised.
The desirable bleb morphology after a
trabeculectomy is different between
limbus-based conjunctival flaps and
another study in which paediatric and
given high doses
patients with limbus-based conjuncti-
val flaps were more likely to develop
cystic blebs (Wells et al. 2003). This
study found that 90% of patients with
limbus-based conjunctival flaps devel-
oped cystic blebs, whereas this only
happened in 29% of patients with for-
nix-based conjunctival flaps.
The precise pathogenic mechanism
after glaucoma surgery is still not
human Tenon fibroblasts from the
subconjunctival space are known to
be the centralplayer
repair and in the scarring processes
(Khaw et al. 1994). Through prolif-
eration, migration, production and
subsequent contraction of extracellu-
Tenon fibroblasts from scar tissue
could be responsible for the filtering
failures of the bleb (Khaw et al.
1994; Occleston et al. 1997). The
bleb behaves clinically as a relatively
aqueous pressure, thereby creating a
dome-shaped bleb (Scott & Quigley
1988). This is different from bleb
scarring, where flattening of the bleb
wall is evident because of myofibro-
Table 1. Relation between type of glaucoma and Stratus optical coherence tomography (OCT)
(n = 17)
(n = 31)
(n = 24)
POAG, NTG, PXS
POAG, primary open-angle glaucoma; NTG, normal-tension glaucoma; PXS, pseudoexfoliation
glaucoma; PACG, primary angle-closure glaucoma.
Table 2. Relation between bleb characteristics and Stratus optical coherence tomography
Indiana bleb appearance grading scale
H0 H1 H2H3E0E1E2E3V0V1 V2V3V4
H, height; E, extent; V, vascularity.
Table 3. Relation between failure bleb characteristics and Stratus optical coherence tomography
Indiana bleb appearance grading scale
H0H1H2H3E0E1 E2E3V0V1V2V3 V4
H, height; E, extent; V, vascularity.
Acta Ophthalmologica 2010
1978). This suggests that non-con-
tractile collagen-producing fibroblasts
play the major role in the process of
the encapsulated bleb. Similarly, con-
tractile fibroblasts are also the major
component in wound healing follow-
ing filtering surgery. We speculate
that the highly reflective walls in
blebs might be reflecting the intensity
of the intrableb fibroblasts. Because
layer-type blebs might have fibroblast
proliferation, this type of bleb was
seen in eyes with poor IOP control.
MMC is applied during filtering
surgery to reduce the risk of bleb fail-
ure (Chen 1983). By inhibiting cell
excessive healing response and scar-
ring, and thus enhances the success of
the procedure. Therefore, we speculate
that MMC might reduce the appear-
ance of layer-type blebs.
In conclusion, Stratus OCT is a
promising tool in the imaging of mor-
phological changes within the bleb tis-
sue. Without Stratus OCT, it may be
difficult to distinguish layer-type blebs
from either cystoid- or diffuse-type
blebs, because there is no relationship
between slit-lamp examinations and
Status OCT examinations. Assessment
of the morphological changes within
the bleb tissue enhances our under-
standing of the bleb function and may
regarding postoperative bleb manage-
This work was supported by Grant-
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Received on February 2nd, 2008.
Accepted on July 14th, 2008.
Department of Ophthalmology
Kagawa University Faculty of Medicine
Tel: +81 87 891 2211
Fax: +81 87 891 2212
Acta Ophthalmologica 2010