Download Spectral Domain Optical Coherence Tomography Imaging of Retinal

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B R I E F
Spectral Domain Optical
Coherence Tomography
Imaging of Retinal Diseases in
Singapore
Mandeep Singh, MRCSEd
Caroline K. L. Chee, FRCSEd
ABSTRACT
In this retrospective case series, the authors reviewed
cases of patients with macular disorders whose eyes had
been imaged using spectral domain optical coherence
tomography (SD-OCT) (Cirrus HD-OCT; Carl Zeiss
Meditec, Inc., Dublin, CA). SD-OCT images were obtained from patients with a variety of ocular conditions
attending a tertiary retinal clinic in Singapore from August 2007 to December 2007, according to standardized protocols. Images of 428 eyes from 301 patients
were reviewed. Ocular diagnoses included diabetic
macular edema, exudative age-related macular degeneration, central serous chorioretinopathy, cystoid macular edema, retinal vein and artery occlusions, infective
chorioretinitis, and others. The authors present four
cases of particular interest to illustrate how SD-OCT
was useful in complementing the clinician’s assessment
of macular disease. [Ophthalmic Surg Lasers Imaging 2008;39:S120-S125.]
INTRODUCTION
Optical coherence tomography (OCT) is a noninvasive imaging modality that provides high-resolution,
cross-sectional images of the retina. Its principles have
been described elsewhere.1,2 It enables clinicians to
diagnose and monitor a number of retinal diseases.2-6
From the Department of Ophthalmology National University Hospital,
Singapore (MS, CKLC), and the Department of Ophthalmology, Yong Loo
Lin School of Medicine, National University of Singapore (CKLC).
Accepted for publication March 14, 2008.
The authors have no grant support to acknowledge or financial interest
to disclose.
Address correspondence to Caroline K. L. Chee, FRCSEd, Department
of Ophthalmology, National University Hospital, 5 Lower Kent Ridge
Road, Singapore 119074.
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R E P O R T
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Conventional time domain OCT (TD-OCT) is limited
by suboptimal image resolution, slow data acquisition,
and poor image registration. The recent introduction
of spectral domain OCT (SD-OCT) has enabled imaging with greater resolution, higher scan speed, wider
sampling area, and improved image registration.7,8
Here, we reviewed cases of patients with retinal disease
whose eyes had been imaged using SD-OCT (Cirrus
HD-OCT; Carl Zeiss Meditec, Inc., Dublin, CA) to
determine the clinical utility of this imaging device in
the assessment of patients with retinal disorders.
DESIGN AND METHODS
In this retrospective case series, we reviewed the records of all patients who had undergone SD-OCT imaging of the retina from August 2007 to December 2007
at a tertiary retinal clinic in Singapore. Most eyes were
also concurrently imaged using TD-OCT (Stratus OCT;
Carl Zeiss Meditec, Inc.); in these cases, we compared
the quality and clinical utility of data obtained using
each method. In all cases, imaging was performed using standardized protocols: the Fast Macular Thickness
Map protocol was used for Stratus OCT (scan length,
6.0 mm; axial resolution, 10 µm) and the 512 × 128
Macular Cube protocol for Cirrus HD-OCT (scan area,
6.0 × 6.0 mm2; axial resolution, 5 µm). Fundal fluorescein angiography (FA) and indocyanine green angiography (ICGA) were performed at the clinician’s discretion.
To facilitate image review, SD-OCT images were color-,
brightness-, and contrast-adjusted until optimal clarity
of detail was obtained. TD-OCT and SD-OCT images
were reviewed and correlated with data from clinical examination and investigations. Here, we discuss four cases
of particular interest to illustrate how SD-OCT imaging
contributed significantly to the clinician’s understanding of the disease. Institutional review board approval
was not obtained because this study was retrospective,
involved the use of devices (Cirrus HD-OCT and Stratus OCT) that were in routine clinical use, and did not
involve randomization of patients.
FINDINGS
SD-OCT images of 428 eyes from 301 patients
with various ocular conditions were reviewed. Diagnoses
OPHTHALMIC SURGERY, LASERS & IMAGING · JULY/AUGUST 2008 · VOL 39, NO 4 (SUPPLEMENT)
A
B
C
D
E
F
G
Figure 1. A, Submacular hemorrhage, OD, in a 68-year-old woman with VA CF at 1 m, OD. The white line denotes the location of TD-OCT
and SD-OCT images shown in C, D, F, and G. B, ICGA showed polypoidal choroidal vasculopathy, OD. The white line denotes the location
of the SD-OCT image shown in E. C, TD-OCT showing macular RPE and retinal detachment with intraretinal edema 3 days after intravitreal
injection of perfluoropropane (C3F8) gas and tissue plasminogen activator. D, SD-OCT showed the location and extent of the RPE detachment in greater detail. Subfoveal fluid is also better seen with SD-OCT. E, The polyps were not visualized on SD-OCT images at the location
suggested by ICGA (white arrow). Only irregularity and thickening of the outer retinal hyperreflective layers corresponding to RPE were seen
at this site. F, One month after direct argon laser photocoagulation of polyps, TD-OCT showed widening of the hyperreflective layers in the
outer retina, RPE detachment, and mild retinal thickening. G, SD-OCT of the same eye in Fig. 2A clearly showing RPE detachment and a
hyperreflective subfoveal area above the RPE (white arrow) not visualized on TD-OCT.
included diabetic macular edema, exudative age-related
macular degeneration, central serous chorioretinopathy,
cystoid macular edema, retinal vein and artery occlusions, infective chorioretinitis, and others. SD-OCT images had greater resolution than TD-OCT and imaged
a greater area of retina in each scan. Topographic retinal
thickness and retinal pigment epithelial (RPE) maps
in the SD-OCT yielded more information than similar depictions on TD-OCT. The localization capability
of the crosshairs of SD-OCT was useful in locating lesions across an area of imaged retina and could be used
in conjunction with angiographic findings. There was
improved patient cooperation with SD-OCT owing to
BRIEF REPORT
fast data acquisition. Optimal resolution of outer retinal
layers was found when SD-OCT images were modulated to a grayscale output and contrast and brightness
were adjusted for each image. In this manner, the layers
of the retina, especially the outer retinal hyperreflective
layers near the RPE and photoreceptor inner segment/
outer segment junctions, appeared maximally distinct
and separate. We discuss four interesting cases in detail
below to illustrate these differences.
Polypoidal Choroidal Vasculopathy
A 68-year-old, nonsmoking woman presented
with poor vision in the left eye for 10 days. Visual acu-
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C
A
B
Figure 2. A, A 16-year-old Indonesian boy with Toxoplasma
chorioretinitis had a pale retinal lesion OD at the fovea and
overlying vitritis with a “headlight-in-the-fog” appearance and a
chorioretinal scar on the inferior macula. The white line denotes
the location of scans shown in C–E. The black line denotes the
location of the scan shown in F. B, FA showed ring-shaped foveal leakage and staining corresponding to the inferior macular
scar. C, TD-OCT showed retinal thickening, loss of normal foveal contour, and shadowing of the subfoveal RPE layer. Central
macular thickness (CMT) was 400 µm. D, Two months after beginning oral anti-Toxoplasma therapy, TD-OCT showed reduced
retinal thickening with a CMT of 276 µm. E, SD-OCT showed
features not seen on TD-OCT such as intraretinal cysts, loss of
normal intraretinal striations in the fovea, thickened posterior
hyaloid with foveal vitreomacular traction, epiretinal membrane,
and attenuation of the hyperreflective layer corresponding to
subfoveal RPE. F, In the same macular cube SD-OCT image,
thinning of the retina, loss of the hyperreflective layers of the
outer retina, and increased light transmission to the choroid
through this atrophic area were seen.
D
E
F
ity (VA) was counting fingers (CF) 1 m in the left eye
due to a large submacular hemorrhage (Fig. 1A) attributable to polypoidal choroidal vasculopathy (Fig.
1B). She received an intravitreal injection of perfluoropropane (C3F8) gas and tissue plasminogen activator. Three days later, the hemorrhage had displaced,
and VA was 20/30 in the left eye. TD-OCT showed
macular RPE detachment, subretinal fluid, and retinal
thickening (Fig. 1C). SD-OCT showed more precisely
the extent of RPE detachment underlying the foveal
detachment (Fig. 1D). The cross-hairs of the SD-OCT
scan output were placed over the polyps as guided by
ICGA. The polyps were not visualized on SD-OCT
images; irregularity and thickening of outer retinal
hyperreflective layers were seen at this site (Fig. 1E).
Direct argon laser photocoagulation of the polyps was
performed. At 1 month, VA was 20/50 in the left eye.
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TD-OCT showed widening of the hyperreflective layers in the outer retina, RPE detachment, and mild
retinal thickening (Fig. 1F). SD-OCT provided more
detailed information, showing RPE detachment and a
hyperreflective subfoveal layer above the RPE (Fig. 1G)
possibly representing altered subretinal blood or scar
that was not visualized on TD-OCT.
Toxoplasma Chorioretinitis
A 16-year-old boy from East Java, Indonesia,
presented with 8 days of visual loss in the right eye.
VA was CF 0.5 m in the right eye. There was a pale
retinal lesion at the fovea and overlying vitritis with
a “headlight-in-the-fog” appearance, and a chorioretinal scar on the inferior macula (Fig. 2A). FA is
shown in Fig. 2B. TD-OCT showed retinal thickening, loss of normal foveal contour, and shadowing of
OPHTHALMIC SURGERY, LASERS & IMAGING · JULY/AUGUST 2008 · VOL 39, NO 4 (SUPPLEMENT)
B
A
C
D
E
Figure 3. A, FA in a 70-year-old man with VA 20/40, OD, showed a vascularized RPE detachment. The black line denotes location of
scans shown in B–D. B, TD-OCT showed a large RPE detachment and minimal retinal thickening. C, SD-OCT showed RPE irregularity and thickening in the region of the choroidal neovascularization. D, After 2 months with no treatment, SD-OCT showed collapse of
the RPE detachment, corrugation of RPE and retina, and intraretinal edema. E, The topographic RPE map of the SD-OCT at 2 months
showed this morphologic change clearly.
the subfoveal RPE layer (Fig. 2C). Central macular
thickness (CMT) was 400 µm. Serology supported
the diagnosis of Toxoplasma chorioretinitis. The patient received oral clindamycin with a tapering regimen of prednisolone over 3 months. At 2 months,
there was a central foveal scar; VA was unchanged
despite complete resolution of retinitis and vitritis.
TD-OCT showed reduced retinal thickening with
a CMT of 276 µm (Fig. 2D). SD-OCT showed in
greater detail a number of features not seen on TDOCT, such as intraretinal cysts, loss of normal intraretinal striations in the fovea, thickened posterior
hyaloid with foveal vitreomacular traction, epiretinal membrane, and attenuation of the hyperreflective layer corresponding to subfoveal RPE (Fig. 2E).
The same 6 × 6-mm2 cube of the SD-OCT scan of
the foveal lesion also captured the second lesion in
BRIEF REPORT
the inferior macula, showing thinning of the retina,
loss of hyperreflective layers of the outer retina, and
increased light transmission to the choroid through
this atrophic area (Fig. 2F).
Spontaneous Collapse of RPE Detachment
A 70-year-old, nonsmoking man presented with
poor vision in the right eye of uncertain duration. VA
was 20/40 in the right eye with a large RPE detachment
centered on the fovea. FA diagnosis was that of vascularized RPE detachment (Fig. 3A). TD-OCT showed a
large RPE detachment and minimal retinal thickening
(Fig. 3B). Guided by the FA, we located the choroidal
neovascularization on SD-OCT where we found thickening and irregularity of the outer retina near the RPE
(Fig. 3C). VA remained stable over 2 months with no
treatment. SD-OCT at 2 months showed collapse of
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ing showed thickening and increased reflectivity of
the inner retina in the infarcted area. The inner retinal
layers were not seen distinctly, and demarcation between normal and infarcted inner retina was unclear
(Fig. 4A). Along the superior edge of the area of retinal infarction, SD-OCT showed areas of disruption of
only inner retinal architecture demarcated from areas
of normal inner retina (Fig. 4B). SD-OCT images
also showed increased separation between inner retinal layers that were identified distinctly. Outer retinal
morphology was relatively normal. At the completely
infarcted inferior macula, outer retinal layers retained a
normal appearance on SD-OCT despite complete inner retinal disorganization with increased reflectivity of
inner retina, loss of inner retinal striations, and inner
retinal thickening (Fig. 4C). The patient was treated
conservatively and vascular risk factors controlled.
A
B
DISCUSSION
C
Figure 4. A, In a 70-year-old man with inferior branch retinal artery
occlusion OD, TD-OCT image across the fovea showed increased
thickness and reflectivity of inner retina. The retinal layers in the
outer and inner retina were not clearly seen. B, SD-OCT showed
areas of disruption of inner retinal architecture (white arrows) interspersed with areas of normal inner retina along the superior
edge of the area of inferior retinal infarction. C, In the completely
infracted inferior macula, outer retinal layers retained a normal
appearance despite complete inner retinal disorganization with
increased reflectivity of inner retina, loss of inner retinal striations,
and inner retinal thickening.
the RPE detachment, full-thickness folds of RPE and
retina, and intraretinal edema (Fig. 3D). The topographic RPE map of SD-OCT demonstrated this morphologic change clearly (Fig. 3E); there was no such
output capability in TD-OCT. The patient was managed conservatively and maintained stable vision.
Branch Retinal Artery Occlusion
A 70-year-old man with hypertension presented
with visual loss in the right eye for 3 days. VA was
20/200 in the right eye due to inferior branch retinal
artery occlusion involving the fovea. TD-OCT imag-
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As found by other investigators, TD-OCT and
SD-OCT provided images of macular anatomy that
added data to clinical assessment.9-11 SD-OCT images
were of greater axial resolution than TD-OCT. This
enabled detection of smaller lesions and improved resolution of larger lesions, compared with TD-OCT. Each
SD-OCT macular cube scan is able to cover a greater
area than TD-OCT line scans, enabling visualization
of multiple lesions with a single scan. Patient cooperation is improved in the faster SD-OCT scans.
The current practice of having to read SD-OCT
output from the monitor attached to the device
posed a minor inconvenience to clinicians, who had
to walk to the machine to review results. We also
found the lack of normative data in the SD-OCT
unit at our center to be a disadvantage in that affected eyes could only be qualitatively compared with
healthy eyes. This may be overcome in the future
with the addition of normal retinal thickness values
obtained in our population.
SD-OCT is a useful tool in macular evaluation
and provides more detailed anatomic information to
the clinician than TD-OCT. The utility of SD-OCT
imaging in clinical management of patients with retinal diseases needs to be further assessed.
REFERENCES
1. Huang D, Swanson EA, Lin CP, et al. Optical coherence tomography. Science. 1991;254:1178-1181.
OPHTHALMIC SURGERY, LASERS & IMAGING · JULY/AUGUST 2008 · VOL 39, NO 4 (SUPPLEMENT)
2. Puliafito CA, Hee MR, Lin CP, et al. Imaging of macular diseases with optical coherence tomography. Ophthalmology. 1995;102:217-229.
3. Hee MR, Baumal CR, Puliafito CA, et al. Optical coherence tomography of age-related macular degeneration and choroidal neovascularization. Ophthalmology.
1996;103:1260-1270.
4. Hee MR, Puliafito CA, Wong C, et al. Quantitative assessment of macular edema with optical coherence tomography. Arch Ophthalmol. 1995;113:1019-1029.
5. Hee MR, Puliafito CA, Wong C, et al. Optical coherence tomography of macular holes. Ophthalmology.
1995;102:748-756.
6. Hee MR, Puliafito CA, Wong C, et al. Optical coherence tomography of central serous chorioretinopathy.
Am J Ophthalmol. 1995;120:65-74.
7. Drexler W, Morgner U, Kartner FX, et al. In vivo
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8.
9.
10.
11.
ultrahigh resolution optical coherence tomography.
Opt Lett. 1999;24:1221-1223.
Drexler W, Morgner U, Ghanta RK, et al. Ultrahighresolution ophthalmic optical coherence tomography. Nat Med. 2001;7:502-507.
Ko TH, Fujimoto JG, Duker JS, et al. Comparison of
ultrahigh- and standard-resolution optical coherence
tomography for imaging macular hole pathology and
repair. Ophthalmology. 2004;111:2033- 2043.
Swanson EA, Izatt JA, Hee MR, et al. In-vivo retinal
imaging by optical coherence tomography. Opt Lett.
1993;18:1864-1866.
Ko TH, Fujimoto JG, Schuman JS, et al. Comparison of ultrahigh and standard resolution optical coherence tomography for imaging of macular pathology. Ophthalmology. 2005;112:1922-1922.
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