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1.  Choroidal Thickness in Retinal Pigment Epithelial Tear as Measured by Spectral Domain Optical Coherence Tomography 
Retina (Philadelphia, Pa.)  2014;34(1):63-68.
Purpose
To evaluate choroidal thickness with spectral domain optical coherence tomography (SDOCT) in subjects with retinal pigment epithelial (RPE) tear as compared with the choroidal thickness of their fellow eye.
Methods
For this cross sectional investigation, 7 eyes of 7 patients with neovascular age-related macular degeneration and RPE tear in one eye imaged with SDOCT were identified. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500-μm intervals up to 2500 μm temporal and nasal to the fovea in both the eye with the RPE tear and the eye with intact RPE. All measurements were performed by 2 independent observers and averaged for the purpose of analysis. Measurements were compared using paired t-test.
Results
The average age of patients was 79 years (range 66-88). All subjects had dome-shaped pigment epithelial detachments (PED) prior to RPE tear and no dome-shaped PED in the unaffected eye. Average subfoveal choroidal thickness in the eye with the RPE tear was 154.9µm ± 10.1µm. Average subfoveal choroidal thickness in the eye with intact RPE was 212.9µm ± 10.6µm (p=0.035).
Conclusion
There is a significant decrease in subfoveal choroidal thickness in subjects with RPE tear as compared with their fellow eye with intact RPE. It is unclear if this thinning is a consequence of or precedes the RPE tear. Further studies are necessary to prospectively follow choroidal thickness in subjects with dome-shaped PED.
doi:10.1097/IAE.0b013e318297a061
PMCID: PMC4058963  PMID: 23764968
choroidal thickness; retinal pigment epithelial tear; spectral domain optical coherence tomography
2.  Retinal Neovascularization Secondary to Proliferative Diabetic Retinopathy Characterized by Spectral Domain Optical Coherence Tomography 
Retina (Philadelphia, Pa.)  2013;33(3):542-547.
Purpose
To characterize diabetic retinal neovascularization and accompanying retinal and vitreal morphological changes using high-resolution spectral domain optical coherence tomography (SD-OCT).
Methods
A cross-sectional retrospective analysis was performed on 16 eyes of 14 nonconsecutive subjects with proliferative diabetic retinopathy that were seen between August 2011 and December 2011 at the New England Eye Center, Boston, Massachusetts. Patients who had neovascularization of the disc (NVD), neovascularization elsewhere (NVE) and intraretinal microvascular abnormalities (IRMAs) were scanned using OCT scans directly over the region of the abnormal vessels.
Results
Characteristic changes of the retinal vasculature, retina and vitreous were seen in the 16 eyes with neovascularization. This study describes OCT characteristics of: 1) NVD; 2) NVE; 3) IRMA; 4) NV causing traction without retinal detachment; 5) NV causing traction with retinal detachment. The morphologic appearance of vitreous traction was found to be consistent with previous histological reports.
Conclusions
It is possible to image diabetic NV using SD-OCT and to visualize the spectrum of retinal, retinal vascular and vitreal changes seen through these areas of abnormal retinal vasculature.
doi:10.1097/IAE.0b013e3182753b6f
PMCID: PMC4058992  PMID: 23400083
Neovascularization of the retina; neovascularization of the disc; intraretinal microvascular abnormalities; diabetes mellitus; proliferative diabetic retinopathy; optical coherence tomography
3.  Bilateral simultaneous central serous chorioretinopathy in a teenage girl with systemic arterial hypertension 
International ophthalmology  2012;33(1):79-82.
Purpose
We present a case of bilateral simultaneous central serous chorioretinopathy (CSCR) in a teenage girl with a history of systemic arterial hypertension.
Methods
A 19 year old Caucasian female, with a history of systemic arterial hypertension, presented with gradual decrease in her central vision for 1 month. She was diagnosed with bilateral simultaneous CSCR, based on the findings of spectral domain optical coherence tomography (SD-OCT), indocyanine green angiography (ICG), fundus auto-fluorescence, fluorescein angiography and color fundus photographs, which are described.
Results: Blood pressure was 134/95 mmHg at presentation
Systemic evaluation failed to reveal a cause for the high blood pressure, and included a panel of blood tests, which were all normal. Her best-corrected visual acuity was 20/30 OD and 20/25 OS. Dilated fundus examination showed normal optic discs and retinal vasculature, with no evidence of hypertensive retinopathy. However, shallow retinal fluid associated with pigmentary changes was noted in the center of both maculae. OCT and ICG findings were consistent with the diagnosis of bilateral CSCR.
Conclusion
CSCR can manifest in patients with demographics outside the range of those previously reported. This is the first report of CSCR occurring in a teenage girl, with a history of systemic arterial hypertension. It is important to consider this disease in any patient who has a clinically compatible presentation.
doi:10.1007/s10792-012-9624-3
PMCID: PMC3536924  PMID: 22983871
Bilateral central serous chorioretinopathy; retinal pigment epithelium (RPE); optical coherence tomography (OCT); indocyanine green angiography (ICG); hypertension
4.  Handheld ultrahigh speed swept source optical coherence tomography instrument using a MEMS scanning mirror 
Biomedical Optics Express  2013;5(1):293-311.
We developed an ultrahigh speed, handheld swept source optical coherence tomography (SS-OCT) ophthalmic instrument using a 2D MEMS mirror. A vertical cavity surface-emitting laser (VCSEL) operating at 1060 nm center wavelength yielded a 350 kHz axial scan rate and 10 µm axial resolution in tissue. The long coherence length of the VCSEL enabled a 3.08 mm imaging range with minimal sensitivity roll-off in tissue. Two different designs with identical optical components were tested to evaluate handheld OCT ergonomics. An iris camera aided in alignment of the OCT beam through the pupil and a manual fixation light selected the imaging region on the retina. Volumetric and high definition scans were obtained from 5 undilated normal subjects. Volumetric OCT data was acquired by scanning the 2.4 mm diameter 2D MEMS mirror sinusoidally in the fast direction and linearly in the orthogonal slow direction. A second volumetric sinusoidal scan was obtained in the orthogonal direction and the two volumes were processed with a software algorithm to generate a merged motion-corrected volume. Motion-corrected standard 6 x 6 mm2 and wide field 10 x 10 mm2 volumetric OCT data were generated using two volumetric scans, each obtained in 1.4 seconds. High definition 10 mm and 6 mm B-scans were obtained by averaging and registering 25 B-scans obtained over the same position in 0.57 seconds. One of the advantages of volumetric OCT data is the generation of en face OCT images with arbitrary cross sectional B-scans registered to fundus features. This technology should enable screening applications to identify early retinal disease, before irreversible vision impairment or loss occurs. Handheld OCT technology also promises to enable applications in a wide range of settings outside of the traditional ophthalmology or optometry clinics including pediatrics, intraoperative, primary care, developing countries, and military medicine.
doi:10.1364/BOE.5.000293
PMCID: PMC3891340  PMID: 24466495
(170.4460) Ophthalmic optics and devices; (170.5755) Retina scanning; (170.3880) Medical and biological imaging; (170.4500) Optical coherence tomography; (170.4470) Ophthalmology
5.  Choriocapillaris and Choroidal Microvasculature Imaging with Ultrahigh Speed OCT Angiography 
PLoS ONE  2013;8(12):e81499.
We demonstrate in vivo choriocapillaris and choroidal microvasculature imaging in normal human subjects using optical coherence tomography (OCT). An ultrahigh speed swept source OCT prototype at 1060 nm wavelengths with a 400 kHz A-scan rate is developed for three-dimensional ultrahigh speed imaging of the posterior eye. OCT angiography is used to image three-dimensional vascular structure without the need for exogenous fluorophores by detecting erythrocyte motion contrast between OCT intensity cross-sectional images acquired rapidly and repeatedly from the same location on the retina. En face OCT angiograms of the choriocapillaris and choroidal vasculature are visualized by acquiring cross-sectional OCT angiograms volumetrically via raster scanning and segmenting the three-dimensional angiographic data at multiple depths below the retinal pigment epithelium (RPE). Fine microvasculature of the choriocapillaris, as well as tightly packed networks of feeding arterioles and draining venules, can be visualized at different en face depths. Panoramic ultra-wide field stitched OCT angiograms of the choriocapillaris spanning ∼32 mm on the retina show distinct vascular structures at different fundus locations. Isolated smaller fields at the central fovea and ∼6 mm nasal to the fovea at the depths of the choriocapillaris and Sattler's layer show vasculature structures consistent with established architectural morphology from histological and electron micrograph corrosion casting studies. Choriocapillaris imaging was performed in eight healthy volunteers with OCT angiograms successfully acquired from all subjects. These results demonstrate the feasibility of ultrahigh speed OCT for in vivo dye-free choriocapillaris and choroidal vasculature imaging, in addition to conventional structural imaging.
doi:10.1371/journal.pone.0081499
PMCID: PMC3859478  PMID: 24349078
7.  OPTICAL COHERENCE TOMOGRAPHY–GUIDED FACEDOWN POSITIONING FOR MACULAR HOLE SURGERY 
Retina (Philadelphia, Pa.)  2013;33(2):356-362.
Purpose
To use spectral domain optical coherence tomography–guided duration of facedown positioning to study anatomical macular hole closure rates.
Methods
Retrospective review of patients with macular holes undergoing 23-gauge pars plana vitrectomy and intraocular gas tamponade. Spectral domain optical coherence tomography imaging was done on postoperative Day 1. Patients remained facedown for 2 more days if the macular hole was closed or 6 more days facedown if the macular hole was open or indeterminate.
Results
There were 8 Stage 2, 12 Stage 3, and 12 Stage 4 macular holes. On postoperative Day 1, 24 holes were closed by spectral domain optical coherence tomography and instructed to remain facedown for two more days. Twenty-three of 24 holes remained closed during the postoperative period. Eight holes were open or indeterminate on postoperative Day 1 and remained facedown for 6 more days. Six of 8 holes (75%) were closed at their last follow-up. The overall closure rate was 29/32 (90.6%). Average follow-up was 334 days.
Conclusion
Confirming early closure of macular holes with spectral domain optical coherence tomography imaging can serve as an important guide to significantly shorten the duration of prone positioning while maintaining high closure rates.
doi:10.1097/IAE.0b013e318263d0e8
PMCID: PMC3758113  PMID: 23343822
facedown positioning; macular hole surgery; optical coherence tomography; prone positioning; spectral domain optical coherence tomography; vitrectomy
8.  Optical coherence tomography – current and future applications 
Current opinion in ophthalmology  2013;24(3):213-221.
Purpose of review
Optical coherence tomography (OCT) has revolutionized the clinical practice of ophthalmology. It is a noninvasive imaging technique that provides high-resolution, cross-sectional images of the retina, retinal nerve fiber layer and the optic nerve head. This review discusses the present applications of the commercially available spectral-domain OCT (SD-OCT) systems in the diagnosis and management of retinal diseases, with particular emphasis on choroidal imaging. Future directions of OCT technology and their potential clinical uses are discussed.
Recent findings
Analysis of the choroidal thickness in healthy eyes and disease states such as age-related macular degeneration, central serous chorioretinopathy, diabetic retinopathy and inherited retinal dystrophies has been successfully achieved using SD-OCT devices with software improvements. Future OCT innovations such as longer-wavelength OCT systems including the swept-source technology, along with Doppler OCT and en-face imaging, may improve the detection of subtle microstructural changes in chorioretinal diseases by improving imaging of the choroid.
Summary
Advances in OCT technology provide for better understanding of pathogenesis, improved monitoring of progression and assistance in quantifying response to treatment modalities in diseases of the posterior segment of the eye. Further improvements in both hardware and software technologies should further advance the clinician’s ability to assess and manage chorioretinal diseases.
doi:10.1097/ICU.0b013e32835f8bf8
PMCID: PMC3758124  PMID: 23429598
applications of optical coherence tomography; chorioretinal diseases; retina; spectral-domain optical coherence tomography; swept-source optical coherence tomography
9.  EXERCISE-INDUCED ACUTE CHANGES IN SYSTOLIC BLOOD PRESSURE DO NOT ALTER CHOROIDAL THICKNESS AS MEASURED BY A PORTABLE SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY DEVICE 
Retina (Philadelphia, Pa.)  2013;33(1):160-165.
Purpose
To measure choroidal thickness in patients manifesting an acute change in systemic arterial blood pressure using a portable spectral-domain optical coherence tomography device (iVue).
Methods
Fifteen patients (15 eyes) undergoing cardiac exercise stress testing were scanned using a portable spectral-domain optical coherence tomography system (iVue). Two scan protocols were used: cross line scan for measuring choroidal thickness and the retina map scan to measure retinal thickness. Each patient was scanned before and within 3 minutes after the stress test. Blood pressure was measured at the same time as the acquisition of the scans. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid–sclera junction at 500-μm intervals up to 1,000 μm temporal and nasal to the fovea. Retinal thickness was measured by an automated software. All choroidal thickness measurements were performed by two independent observers.
Results
Fifteen patients (15 eyes) with a mean age of 60.6 (±10.4 years) were scanned. There was a significant increase in systolic but not diastolic pressure after stress testing (P < 0.05). The mean choroidal thickness measurements showed no significant difference before and after exercise stress testing (P > 0.05). In addition, there was no significant difference in retinal thickness before and after stress testing measurements (P > 0.05).
Conclusion
There was no change in choroidal thickness or retinal thickness, despite an acute change in the systemic systolic blood pressure induced by exercise.
doi:10.1097/IAE.0b013e3182618c22
PMCID: PMC3758128  PMID: 22869027
choroid; choroidal thickness; optical coherence tomography (OCT); retinal thickness; stress test; choroidal blood flow; blood pressure
10.  Phase-sensitive swept source OCT imaging of the human retina with a VCSEL light source 
Optics letters  2013;38(3):338-340.
Despite the challenges in achieving high phase stability, Doppler swept source / Fourier domain OCT has advantages of less fringe washout and faster imaging speeds compared to spectral / Fourier domain detection. This manuscript demonstrates swept source OCT with a VCSEL light source at 400kHz sweep rate for phase-sensitive Doppler imaging, measuring pulsatile total retinal blood flow with high sensitivity and phase stability. A robust, simple, and computationally efficient phase stabilization approach for phase-sensitive swept source imaging is also presented.
PMCID: PMC3721635  PMID: 23381430
11.  De-novo Appearance of a Choroidal Osteoma in an Eye with Previous Branch Retinal Vein Occlusion 
This report describes the de-novo appearance of a choroidal osteoma in an eye, following years after laser photocoagulation for previous branch retinal vein occlusion (BRVO). A 62-year old male presented with an asymptomatic yellowish-orange lesion in the macula on fundus examination of his left eye, during a regular follow up visit for bilateral BRVO associated with macular edema, which had been treated with laser photocoagulation many years ago. The lesion was observed for 1.5 years until decrease in vision occurred. Fundus photography revealed a yellow-to-orange, well-defined lesion in the macular region. Fluorescein angiography was consistent with choroidal neovascularization (CNV). OCT and B-scan ultrasonography showed features consistent with choroidal osteoma. This is the first report of the de-novo appearance of a choroidal osteoma in an eye, following years after laser photocoagulation for BRVO. CNV developed secondary to the lesion, which was treated with intravitreal Bevacizumab, leading to subjective and anatomic improvement.
doi:10.3928/23258160-20121221-17
PMCID: PMC3717569  PMID: 23410812
BRVO; choroidal osteoma; CNV; intravitreal Bevacizumab; laser photocoagulation; OCT; sub-retinal fluid
12.  Swept source / Fourier domain polarization sensitive optical coherence tomography with a passive polarization delay unit 
Optics Express  2012;20(9):10229-10241.
Polarization sensitive optical coherence tomography (PS-OCT) is a functional imaging method that provides additional contrast using the light polarizing properties of a sample. This manuscript describes PS-OCT based on ultrahigh speed swept source / Fourier domain OCT operating at 1050nm at 100kHz axial scan rates using single mode fiber optics and a multiplexing approach. Unlike previously reported PS-OCT multiplexing schemes, the method uses a passive polarization delay unit and does not require active polarization modulating devices. This advance decreases system cost and avoids complex synchronization requirements. The polarization delay unit was implemented in the sample beam path in order to simultaneously illuminate the sample with two different polarization states. The orthogonal polarization components for the depth-multiplexed signals from the two input states were detected using dual balanced detection. PS-OCT images were computed using Jones calculus. 3D PS-OCT imaging was performed in the human and rat retina. In addition to standard OCT images, PS-OCT images were generated using contrast form birefringence and depolarization. Enhanced tissue discrimination as well as quantitative measurements of sample properties was demonstrated using the additional contrast and information contained in the PS-OCT images.
doi:10.1364/OE.20.010229
PMCID: PMC3366588  PMID: 22535114
(170.4500) Optical coherence tomography; (230.5440) Polarization-selective devices; (170.4580) Optical diagnostics for medicine; (170.4470) Ophthalmology
13.  In vivo imaging of the rodent eye with swept source/Fourier domain OCT 
Biomedical Optics Express  2013;4(2):351-363.
Swept source/Fourier domain OCT is demonstrated for in vivo imaging of the rodent eye. Using commercial swept laser technology, we developed a prototype OCT imaging system for small animal ocular imaging operating in the 1050 nm wavelength range at an axial scan rate of 100 kHz with ~6 µm axial resolution. The high imaging speed enables volumetric imaging with high axial scan densities, measuring high flow velocities in vessels, and repeated volumetric imaging over time. The 1050 nm wavelength light provides increased penetration into tissue compared to standard commercial OCT systems at 850 nm. The long imaging range enables multiple operating modes for imaging the retina, posterior eye, as well as anterior eye and full eye length. A registration algorithm using orthogonally scanned OCT volumetric data sets which can correct motion on a per A-scan basis is applied to compensate motion and merge motion corrected volumetric data for enhanced OCT image quality. Ultrahigh speed swept source OCT is a promising technique for imaging the rodent eye, proving comprehensive information on the cornea, anterior segment, lens, vitreous, posterior segment, retina and choroid.
doi:10.1364/BOE.4.000351
PMCID: PMC3567721  PMID: 23412778
(170.3880) Medical and biological imaging; (170.4500) Optical coherence tomography; (170.4470) Ophthalmology
14.  Reproducibility of Choroidal Thickness Measurements Across Three Spectral Domain Optical Coherence Tomography Systems 
Ophthalmology  2011;119(1):119-123.
Purpose
To investigate the reproducibility of choroidal thickness measurements in normal subjects on three Spectral Domain Optical Coherence Tomography (SDOCT) instruments, Zeiss Cirrus HD-OCT (Carl Zeiss Meditec Inc, Dublin, California, USA), Heidelberg Spectralis (Heidelberg Engineering, Heidelberg, Germany) and Optovue RTVue (Optovue Inc., Fremont, CA).
Design
Cross-sectional non-interventional study
Participants
Images were obtained in 28 eyes of 28 healthy undilated volunteers without ocular pathology in a clinical setting.
Methods
All subjects were imaged on the fovea using Cirrus HD 1-line raster, Spectralis enhanced depth imaging and RTVue retina-cross.
Main Outcome Measures
The choroid was measured subfoveally, 750 μm temporal and 750 μm nasal to the fovea. All measurements were performed by 2 independent observers. Two way analysis of variance (ANOVA) with Bonferroni's post-test, Pearson correlation and the Bland-Altman analysis were used to compare measurements.
Results
The group of 28 subjects consisted of 7 men and 21 women, with an average age of 35.2 years (range, 23 to 64 years). A two way ANOVA with Bonferroni's post-test revealed no significant difference in the average subfoveal choroidal thickness (P >0.05) between systems for any location: subfoveally, 750μm temporal and 750 μm nasal to the fovea. The measurements of choroidal thickness from any pair of three instruments (Cirrus vs. Spectralis, Cirrus vs. RTVue, Spectralis vs. RTVue) were also strongly correlated. The Pearson correlation between all two system pairs of the three systems was greater than 0.9 p <0.0001. The 95% limits of agreement between four choroidal thickness measurements between Cirrus and RTVue were +11.21% to -13.57% (Bias -1.17), between Spectralis and RTVue +10.85% to -12.45% (Bias -0.80) and between Cirrus and Spectralis +12.81% to -13.33% (Bias -0.25).
Conclusions
In our population of young healthy adults with normal vision, there was good reproducibility between choroidal thickness measurements of images acquired with Cirrus, Spectralis and RTVue.
doi:10.1016/j.ophtha.2011.07.002
PMCID: PMC3251715  PMID: 21943786
15.  Retinal, anterior segment and full eye imaging using ultrahigh speed swept source OCT with vertical-cavity surface emitting lasers 
Biomedical Optics Express  2012;3(11):2733-2751.
We demonstrate swept source OCT utilizing vertical-cavity surface emitting laser (VCSEL) technology for in vivo high speed retinal, anterior segment and full eye imaging. The MEMS tunable VCSEL enables long coherence length, adjustable spectral sweep range and adjustable high sweeping rate (50–580 kHz axial scan rate). These features enable integration of multiple ophthalmic applications into one instrument. The operating modes of the device include: ultrahigh speed, high resolution retinal imaging (up to 580 kHz); high speed, long depth range anterior segment imaging (100 kHz) and ultralong range full eye imaging (50 kHz). High speed imaging enables wide-field retinal scanning, while increased light penetration at 1060 nm enables visualization of choroidal vasculature. Comprehensive volumetric data sets of the anterior segment from the cornea to posterior crystalline lens surface are also shown. The adjustable VCSEL sweep range and rate make it possible to achieve an extremely long imaging depth range of ~50 mm, and to demonstrate the first in vivo 3D OCT imaging spanning the entire eye for non-contact measurement of intraocular distances including axial eye length. Swept source OCT with VCSEL technology may be attractive for next generation integrated ophthalmic OCT instruments.
doi:10.1364/BOE.3.002733
PMCID: PMC3493240  PMID: 23162712
(110.4500) Optical coherence tomography; (120.4640) Optical instruments; (140.3600) Lasers, tunable; (170.4460) Ophthalmic optics and devices; (170.4470) Ophthalmology
16.  Analysis of Normal Peripapillary Choroidal Thickness via Spectral Domain Optical Coherence Tomography 
Ophthalmology  2011;118(10):2001-2007.
PURPOSE
To analyze the normal peripapillary choroidal thickness utilizing a commercial spectral domain optical coherence tomography (OCT) device and determine the inter-grader reproducibility of this method.
DESIGN
Retrospective, non-comparative, non-interventional case series.
PARTICIPANTS
Thirty-six eyes of 36 normal patients seen at the New England Eye Center between April and September 2010.
METHODS
All patients underwent high-definition scanning with the Cirrus HD-OCT. Two raster scans were obtained per eye, a horizontal and a vertical scan, both of which were centered at the optic nerve. Two independent graders individually measured the choroidal thickness. Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid-scleral junction at 500 μm intervals away from the optic nerve in the superior, inferior, nasal and temporal quadrants. Statistical analysis was conducted to compare mean choroidal thicknesses. Inter-grader reproducibility was assessed by intraclass correlation coefficient and Pearson’s correlation coefficient. Average choroidal thickness in each quadrant was compared to retinal nerve fiber layer (RNFL) thickness in their respective quadrants.
MAIN OUTCOME MEASURES
Peripapillary choroidal thickness, intraclass coefficient, Pearson’s correlation coefficient.
RESULTS
The peripapillary choroid in the inferior quadrant was significantly thinner compared to all other quadrants (p< 0.001). None of the other quadrants were significantly different from each other in terms of thickness. The inferior peripapillary choroid was significantly thinner compared to all other quadrants at all distances measured away from the optic nerve (p< 0.001). Generally, the peripapillary choroid increases in thickness the farther it was away from the optic nerve and eventually approaching a plateau. Intraclass correlation coefficient ranged from 0.62 to 0.93 and Pearson’s correlation coefficient ranged from 0.74 to 0.95 (p< 0.001). Neither RNFL thickness nor average age was significantly correlated with average choroidal thickness.
CONCLUSIONS
Manual segmentation of the peripapillary choroidal thickness is reproducible between graders suggesting that this method is accurate. The inferior peripapillary choroid was significantly thinner than all other quadrants (p< 0.001).
doi:10.1016/j.ophtha.2011.02.049
PMCID: PMC3184379  PMID: 21703691
17.  Analysis of Choroidal Thickness in Age-Related Macular Degeneration Using Spectral-Domain Optical Coherence Tomography 
American Journal of Ophthalmology  2011;152(4):663-668.
Purpose
To understand the relationship between choroidal thickness and various disease factors in patients with age-related macular degeneration (AMD) using spectral-domain optical coherence tomography.
Design
Cross-sectional, retrospective analysis.
Methods
Fifty-seven eyes of 47 patients with wet and dry AMD seen between November 2009 and January 2010 at the New England Eye Center, Boston, Massachusetts, were analyzed. Choroidal thickness was measured by 2 independent observers at 11 sites with high-definition horizontal 1-line raster scans through the foveal center. A retrospective chart review was performed to obtain data concerning duration of disease, number of intravitreal anti–vascular endothelial growth factor injections, visual acuity, lens status, and concomitant retinal pathologic features. The Pearson correlation and Student t test were used for statistical analysis for assessment of choroidal thickness changes in wet and dry AMD.
Results
The choroid in eyes with wet and dry AMD demonstrated a wide range of thicknesses above and below the normal mean (range, 77.5 to 399.5 μm; standard deviation [SD], 90.2). Nearly one third (33.3%) of the eyes with AMD measured less than 1 SD below the mean. Eyes with wet AMD demonstrated a mean subfoveal choroidal thickness of 194.6 μm (SD, 88.4; n = 40) compared with 213.4 μm (SD, 92.2; n = 17) in the dry AMD group. The choroidal thickness in eyes with dry AMD was correlated inversely with age (r = −0.703; P = .002); however, analysis of the number of intravitreal anti–vascular endothelial growth factor injections, number of years of disease, and visual acuity failed to demonstrate any significant correlations with choroidal thickness.
Conclusions
This study demonstrated that choroidal thickness can be measured by spectral-domain optical coherence tomography and that variable choroidal thickness exists among patients with the clinical diagnosis of wet and dry AMD. However, it is unclear at this time why in some eyes, choroidal thickness either increases or decreases with the disease. Further studies need to be carried out to understand the significance of choroidal thickness with respect to visual function and disease progression over time.
doi:10.1016/j.ajo.2011.03.008
PMCID: PMC3375176  PMID: 21708378
18.  CHOROIDAL THICKNESS IN PATIENTS WITH DIABETIC RETINOPATHY ANALYZED BY SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY 
Retina (Philadelphia, Pa.)  2012;32(3):563-568.
Purpose
This study was designed to examine choroidal thickness in patients with diabetes using spectral-domain optical coherence tomography.
Methods
Forty-nine patients (49 eyes) with diabetes and 24 age-matched normal subjects underwent high-definition raster scanning using spectral-domain optical coherence tomography with frame enhancement software. Patients with diabetes were classified into 3 groups: 11 patients with mild or moderate nonproliferative diabetic retinopathy and no macular edema, 18 patients with nonproliferative diabetic retinopathy and diabetic macular edema, and 20 patients with treated proliferative diabetic retinopathy and no diabetic macular edema (treated proliferative diabetic retinopathy). Choroidal thickness was measured from the posterior edge of the retinal pigment epithelium to the choroid/sclera junction at 500-μm intervals up to 2,500 μm temporal and nasal to the fovea.
Results
Reliable measurements of choroidal thickness were obtainable in 75.3% of eyes examined. Mean choroidal thickness showed a pattern of thinnest choroid nasally, thickening in the subfoveal region, and thinning again temporally in normal subjects and patients with diabetes. Mean subfoveal choroidal thickness was thinner in patients with diabetic macular edema (63.3 μm, 27.2%, P < 0.05) or treated proliferative diabetic retinopathy (69.6 μm, 30.0%, P < 0.01), compared with normal subjects. There was no difference between nonproliferative diabetic retinopathy and normal subjects.
Conclusion
Choroidal thickness is altered in diabetes and may be related to the severity of retinopathy. Presence of diabetic macular edema is associated with a significant decrease in the choroidal thickness.
doi:10.1097/IAE.0b013e31822f5678
PMCID: PMC3393081  PMID: 22374157
choroid; choroidal angiopathy; diabetes mellitus; diabetic retinopathy; optical coherence tomography
19.  Evaluation of Choroidal Thickness in Central Serous Chorioretinopathy Using Cirrus HD Optical Coherence Tomography 
Retina (Philadelphia, Pa.)  2010;30(8):1320-1322.
doi:10.1097/IAE.0b013e3181e798b1
PMCID: PMC3355199  PMID: 20827146
Central serous chorioretinopathy; Choroid; Optical coherence tomography; Spectral Fourier Domain
20.  The Role of Spectral-Domain OCT in the Diagnosis and Management of Neovascular Age-Related Macular Degeneration 
Spectral-domain optical coherence tomography (SD-OCT) has emerged as the ancillary examination of choice to assist the diagnosis and management of neovascular age-related macular degeneration (AMD). SD-OCT provides more detailed images of intraretinal, subretinal, and subretinal pigment epithelium fluid when compared to time-domain technology, leading to higher and earlier detection rates of neovascular AMD activity. Improvements in image analysis and acquisition speed make it important for decision-making in the diagnosis and treatment of this disease. However, this new technology needs to be validated for its role in the improvement of visual outcomes in the context of anti-angiogenic therapy.
doi:10.3928/15428877-20110627-05
PMCID: PMC3375172  PMID: 21790112
21.  CHOROIDAL IMAGING USING SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY 
Retina (Philadelphia, Pa.)  2012;32(5):865-876.
Background
A structurally and functionally normal choroidal vasculature is essential for retinal function. Therefore, a precise clinical understanding of choroidal morphology should be important for understanding many retinal and choroidal diseases.
Methods
PUBMED (http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed) was used for most of the literature search for this article. The criterion for inclusion of an article in the references for this review was that it included materials about both the clinical and the basic properties of choroidal imaging using spectral-domain optical coherence tomography.
Results
Recent reports show successful examination and accurate measurement of choroidal thickness in normal and pathologic states using spectral-domain optical coherence tomography systems. This review focuses on the principles of the new technology that make choroidal imaging using optical coherence tomography possible and on the changes that subsequently have been documented to occur in the choroid in various diseases. Additionally, it outlines future directions in choroidal imaging.
Conclusion
Optical coherence tomography is now proven to be an effective noninvasive tool to evaluate the choroid and to detect choroidal changes in pathologic states. Additionally, choroidal evaluation using optical coherence tomography can be used as a parameter for diagnosis and follow-up.
doi:10.1097/IAE.0b013e318251a3a8
PMCID: PMC3381654  PMID: 22487582
optical coherence tomography; choroid; age-related macular degeneration; central serous chorioretinopathy; diabetic retinopathy
22.  Swept source/Fourier domain polarization sensitive optical coherence tomography with a passive polarization delay unit 
Optics Express  2012;20(9):10229-10241.
Polarization sensitive optical coherence tomography (PS-OCT) is a functional imaging method that provides additional contrast using the light polarizing properties of a sample. This manuscript describes PS-OCT based on ultrahigh speed swept source / Fourier domain OCT operating at 1050nm at 100kHz axial scan rates using single mode fiber optics and a multiplexing approach. Unlike previously reported PS-OCT multiplexing schemes, the method uses a passive polarization delay unit and does not require active polarization modulating devices. This advance decreases system cost and avoids complex synchronization requirements. The polarization delay unit was implemented in the sample beam path in order to simultaneously illuminate the sample with two different polarization states. The orthogonal polarization components for the depth-multiplexed signals from the two input states were detected using dual balanced detection. PS-OCT images were computed using Jones calculus. 3D PS-OCT imaging was performed in the human and rat retina. In addition to standard OCT images, PS-OCT images were generated using contrast form birefringence and depolarization. Enhanced tissue discrimination as well as quantitative measurements of sample properties was demonstrated using the additional contrast and information contained in the PS-OCT images.
PMCID: PMC3366588  PMID: 22535114
23.  Measurement of pulsatile total blood flow in the human and rat retina with ultrahigh speed spectral/Fourier domain OCT 
Biomedical Optics Express  2012;3(5):1047-1061.
We present an approach to measure pulsatile total retinal arterial blood flow in humans and rats using ultrahigh speed Doppler OCT. The axial blood velocity is measured in an en face plane by raster scanning and the flow is calculated by integrating over the vessel area, without the need to measure the Doppler angle. By measuring flow at the central retinal artery, the scan area can be very small. Combined with ultrahigh speed, this approach enables high volume acquisition rates necessary for pulsatile total flow measurement without modification in the OCT system optics. A spectral domain OCT system at 840nm with an axial scan rate of 244kHz was used for this study. At 244kHz the nominal axial velocity range that could be measured without phase wrapping was ±37.7mm/s. By repeatedly scanning a small area centered at the central retinal artery with high volume acquisition rates, pulsatile flow characteristics, such as systolic, diastolic, and mean total flow values, were measured. Real-time Doppler C-scan preview is proposed as a guidance tool to enable quick and easy alignment necessary for large scale studies. Data processing for flow calculation can be entirely automatic using this approach because of the simple and robust algorithm. Due to the rapid volume acquisition rate and the fact that the measurement is independent of Doppler angle, this approach is inherently less sensitive to involuntary eye motion. This method should be useful for investigation of small animal models of ocular diseases as well as total blood flow measurements in human patients in the clinic.
doi:10.1364/BOE.3.001047
PMCID: PMC3342181  PMID: 22567595
(170.3880) Medical and biological imaging; (170.4500) Optical coherence tomography; (280.2490) Flow diagnostics; (170.4470) Ophthalmology
24.  Documentation of Intraretinal Retinal Pigment Epithelium Migration via High Speed Ultrahigh Resolution Optical Coherence Tomography 
Ophthalmology  2010;118(4):687-693.
PURPOSE
To describe the features of intraretinal retinal pigment epithelium (RPE) migration documented on a prototype spectral domain high speed, ultrahigh resolution optical coherence tomography (OCT) device in a group of patients with early to intermediate dry age-related macular degeneration (AMD). To correlate intraretinal RPE migration on OCT to RPE pigment clumping on fundus photographs.
DESIGN
Retrospective, non-comparative, non-interventional case series.
PARTICIPANTS
Fifty-five eyes of 44 patients seen at the New England Eye Center between December 2007 and June 2008 with early to intermediate dry AMD.
METHODS
3D OCT scan sets from all patients were analyzed for presence of intraretinal RPE migration, defined as small discreet hyper-reflective and highly-backscattering lesions within the neurosensory retina. Fundus photographs were also analyzed to determine the presence of RPE pigment clumping, defined as black-colored, often spiculated areas of pigment clumping within the macula. OCT en face images were correlated with fundus photographs to demonstrate correspondence of intraretinal RPE migration on OCT and RPE clumping on fundus photo.
MAIN OUTCOME MEASURES
Drusen, Dry AMD, intraretinal RPE migration, RPE pigment clumping.
RESULTS
54.5% of eyes (61.4% of patients) demonstrated intraretinal RPE migration on OCT scans. 56.4% of the fundus photographs demonstrated RPE pigment clumping. All eyes with intraretinal RPE migration on OCT had corresponding RPE pigment clumping on fundus photographs. RPE pigment migrated most frequently into the outer nuclear layer (66.7% of eyes) and less frequently into more anterior retinal layers. Intraretinal RPE migration mainly occurred above areas of drusen (73.3% of eyes).
CONCLUSIONS
The appearance of intraretinal RPE migration on OCT is a common occurrence in early to intermediate dry AMD, occurring in 54.5% of eyes or 61.4% of patients. The area of intraretinal RPE migration on OCT always correlated to areas of pigment clumping on fundus photography. Conversely, all but one eye with RPE pigment clumping on fundus photography also had areas of intraretinal RPE migration on OCT. The high incidence of intraretinal RPE migration observed above areas of drusen suggests that drusen may play physical and catalytic roles in facilitating intraretinal RPE migration in dry AMD patients.
doi:10.1016/j.ophtha.2010.08.010
PMCID: PMC3070873  PMID: 21093923
25.  Computerized Macular Pathology Diagnosis in Spectral Domain Optical Coherence Tomography Scans Based on Multiscale Texture and Shape Features 
With recent improvements on OCT technologies, the sheer volume of the image data keeps increasing. Automated diagnosing system is needed to assist busy clinicians by facilitating timely interpretation of OCT images.
Purpose.
To develop an automated method to identify the normal macula and three macular pathologies (macular hole [MH], macular edema [ME], and age-related macular degeneration [AMD]) from the fovea-centered cross sections in three-dimensional (3D) spectral-domain optical coherence tomography (SD-OCT) images.
Methods.
A sample of SD-OCT macular scans (macular cube 200 × 200 or 512 × 128 scan protocol; Cirrus HD-OCT; Carl Zeiss Meditec, Inc., Dublin, CA) was obtained from healthy subjects and subjects with MH, ME, and/or AMD (dataset for development: 326 scans from 136 subjects [193 eyes], and dataset for testing: 131 scans from 37 subjects [58 eyes]). A fovea-centered cross-sectional slice for each of the SD-OCT images was encoded using spatially distributed multiscale texture and shape features. Three ophthalmologists labeled each fovea-centered slice independently, and the majority opinion for each pathology was used as the ground truth. Machine learning algorithms were used to identify the discriminative features automatically. Two-class support vector machine classifiers were trained to identify the presence of normal macula and each of the three pathologies separately. The area under the receiver operating characteristic curve (AUC) was calculated to assess the performance.
Results.
The cross-validation AUC result on the development dataset was 0.976, 0.931, 0939, and 0.938, and the AUC result on the holdout testing set was 0.978, 0.969, 0.941, and 0.975, for identifying normal macula, MH, ME, and AMD, respectively.
Conclusions.
The proposed automated data-driven method successfully identified various macular pathologies (all AUC > 0.94). This method may effectively identify the discriminative features without relying on a potentially error-prone segmentation module.
doi:10.1167/iovs.10-7012
PMCID: PMC3208114  PMID: 21911579

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