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Multidisciplinary Ophthalmic Imaging  |   August 2014
Simultaneous Investigation of Vascular and Retinal Pigment Epithelial Pathologies of Exudative Macular Diseases by Multifunctional Optical Coherence Tomography
Author Affiliations & Notes
  • Young-Joo Hong
    Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
    Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan
  • Masahiro Miura
    Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan
    Department of Ophthalmology, Ibaraki Medical Center, Tokyo Medical University, Ami, Ibaraki, Japan
  • Myeong Jin Ju
    Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada
  • Shuichi Makita
    Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
    Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan
  • Takuya Iwasaki
    Department of Ophthalmology, Ibaraki Medical Center, Tokyo Medical University, Ami, Ibaraki, Japan
  • Yoshiaki Yasuno
    Computational Optics Group, University of Tsukuba, Tsukuba, Ibaraki, Japan
    Computational Optics and Ophthalmology Group, Tsukuba, Ibaraki, Japan
Investigative Ophthalmology & Visual Science August 2014, Vol.55, 5016-5031. doi:10.1167/iovs.14-14005
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      Young-Joo Hong, Masahiro Miura, Myeong Jin Ju, Shuichi Makita, Takuya Iwasaki, Yoshiaki Yasuno; Simultaneous Investigation of Vascular and Retinal Pigment Epithelial Pathologies of Exudative Macular Diseases by Multifunctional Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2014;55(8):5016-5031. doi: 10.1167/iovs.14-14005.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose.: To investigate exudative macular disease, multifunctional optical coherence tomography (MF-OCT) using a 1-μm probe band was developed. The clinical utility of MF-OCT was examined in a descriptive case series.

Methods.: Ten eyes of nine subjects with exudative macular disease, including one eye with age-related macular degeneration (AMD), one eye with idiopathic neovascular maculopathy, and eight eyes with polypoidal choroidal vasculopathy (PCV), were investigated. Areas of 6 × 6 mm2 around the pathologic region were scanned with 512 × 1024 depth scans in 6.6 seconds. Structural OCT, Doppler optical coherence angiography (OCA), and cumulative phase retardation images were obtained with a single measurement. Each MF-OCT image visualized the structure, vasculature, and birefringence. Degree of polarization uniformity values were also obtained for selective visualization of the retinal pigment epithelium (RPE). The MF-OCT images were compared with conventional ophthalmic images.

Results.: Abnormal vasculatures were observed with Doppler OCA in all eyes, which presented high similarity to indocyanine green angiography in the midphase. The RPE and exudation in the pathologic regions were discriminated in one eye with AMD and five of eight eyes with PCV. Cumulative phase retardation visualized fibrosis scars in two of the PCV cases.

Conclusions.: Multifunctional OCT revealed depth-resolved abnormal vasculatures, the integrity of the RPE and choroid, discrimination of the RPE and exudation, and existence of fibrosis scars in exudative macular diseases. Interpretation of MF-OCT examination is well matched with conventional ophthalmic examination. These results suggest that MF-OCT can be used as a noninvasive ophthalmic examination tool prior to conventional examinations in clinical routines.

Introduction
Exudative macular diseases threaten vision ability in humans. Among these, age-related macular degeneration (AMD) is one of the leading causes of irreversible blindness in elderly people over 65 years in developed countries. 13 Age-related macular degeneration is the third-ranking cause of blindness worldwide. 4 Choroidal neovascularization (CNV) frequently appears as a result of AMD progression. Polypoidal choroidal vasculopathy (PCV) is one form of AMD and is characterized by a branching vascular network (BVN) terminating in polypoidal lesions. 5,6  
To diagnose AMD and PCV for appropriate treatment, fluorescence angiography (FA) and indocyanine green angiography (ICGA) are required. It is also known that abnormal choroidal vascularization is triggered by overexpression of vessel endothelial growth factor (VEGF) from an abnormally functioning retinal pigment epithelium (RPE) due to inflammation or hypoxia. 79  
Intravitreal injection of anti-VEGF, such as ranibizumab, bevacizumab, or aflibercept, is one of the most effective treatments for the inhibition of abnormal choroidal vessel creation. 10,11 This treatment requires repeated injections of several rounds within 1- to 3-month periods, and monthly examination is required for building an appropriate strategy for anti-VEGF therapy. However, periodic examinations with FA and ICGA have been restricted because of the possibility of severe complications, 12,13 patient discomfort, and relatively long measurement time. 
Optical coherence tomography (OCT) has been an innovative ophthalmic diagnostic modality that provides noninvasive optical biopsy imaging. 14 Cross-sectional OCT images have been used to study the structure of angiographic lesions appearing in FA or ICGA 15,16 ; however, there is a limitation because OCT imaging does not contrast vessels definitively. Doppler OCT has been demonstrated for flow imaging, 1719 and its in vivo retinal blood flow imaging was also demonstrated. 20,21 As a noninvasive angiographic modality, the first Doppler optical coherence angiography (OCA) was introduced based on 840-nm spectral-domain OCT (SD-OCT). 22 For deep vascular imaging, high-penetration Doppler OCA has also been demonstrated based on 1-μm SD-OCT and 1-μm swept-source OCT (SS-OCT). 2327 Doppler OCA is able to contrast blood flow or the vasculature by measuring the blood flow–induced Doppler shift frequency. Furthermore, the clinical utility of Doppler OCA has been demonstrated through descriptive clinical case studies. 28,29  
Degradation of the RPE plays a considerable role in the development of AMD 30 ; hence, RPE integrity imaging is important in evaluation of the pathophysiological condition of eyes with AMD. For this reason, fundus autofluorescence (FAF), which visualizes the metabolic activity of the RPE with autofluorescence of lipofuscin in the RPE, 31,32 is widely used to evaluate AMD. Polarimetry imaging is an alternative method to evaluate RPE integrity. 33 Depth-resolved polarimetry imaging has been demonstrated with polarization-sensitive OCT (PS-OCT), which is capable of measuring the birefringence of tissue. 3437 Retinal pigment epithelium–discriminable imaging has been demonstrated with the degree of polarization uniformity (DOPU) values obtained by PS-OCT, 3840 and its clinical utility has also been shown. 41,42  
The combination of Doppler OCT and PS-OCT has been demonstrated with a 1.3-μm probing wavelength for blood flow and birefringence imaging of skin. 43,44 Our group recently demonstrated multifunctional Jones matrix OCT (MF-OCT) for simultaneous Doppler and polarization-sensitive imaging, 45 as well as with an advanced version. 46 This MF-OCT provided registered cross-sectional images of structural OCT, Doppler OCA, birefringence tomography, and DOPU imaging with a single measurement. In addition, this MF-OCT uses a 1-μm probing wavelength, hence is capable of investigating the retina and choroid. 
The purpose of our study was to evaluate the clinical utility of MF-OCT as a noninvasive comprehensive ophthalmic imaging modality. Here we introduce a custom-built MF-OCT 46 to investigate the vascular and RPE pathology of exudative macular diseases. A descriptive case series of AMD, neovascular maculopathy, and PCV is presented. Through detailed discussion of the cases, the clinical utility of MF-OCT is also demonstrated. 
Subjects and Methods
Subjects
Ten eyes of nine Japanese subjects were involved in the study, as summarized in Table 1. These included one eye of one subject with idiopathic neovascular maculopathy, one eye of one subject with AMD, and eight eyes of seven subjects with PCV. The number of PCV cases was set to be larger than for other cases because the proportion of AMD patients with PCV is high in Asian countries and proper diagnosis of PCV is crucial. The mean age of the patients was 66.4 (standard deviation [SD]: 10.3) years, and the age ranged from 43 to 80 years. The mean spherical equivalent refractive error of the eyes was −1.4 (SD: 2.7) diopters (D), ranging from −5 to 1.5 D. 
Table 1
 
Summary of Subjects
Table 1
 
Summary of Subjects
Case Eye Sex Age, y Diagnosis
Subject 1 Right Male 68 AMD
Subject 2 Left Male 43 NM
Subject 3 Left Female 67 PCV
Subject 4 Right Male 73 PCV
Left PCV
Subject 5 Left Male 80 PCV
Subject 6 Left Male 58 PCV
Subject 7 Right Male 68 PCV
Subject 8 Left Male 66 PCV
Subject 9 Left Female 69 PCV
The patients were diagnosed at the Tokyo Medical University Ibaraki Medical Center. Subjects received a comprehensive ophthalmic examination; that is, FA, ICGA, and short wavelength FAF were performed using a confocal scanning laser ophthalmoscope (F-10; Nidek, Aichi, Japan). After ophthalmic examination, the subjects were transferred to an optics laboratory at the University of Tsukuba, where their eyes were scanned with a custom-built MF-OCT. The research protocol adhered to the tenets of the Declaration of Helsinki and was approved by the institutional review board of Tokyo Medical University and the University of Tsukuba. Informed consent was obtained from the subjects after an explanation of the nature and possible consequences of the research was provided. 
Multifunctional Jones Matrix Optical Coherence Tomography
The MF-OCT is a prototype device built by the Computational Optics Group at the University of Tsukuba. This MF-OCT is based on SS-OCT technology with a 1-μm probing wavelength and offers a measurement speed of 100,000 A-lines/s. 
Because our MF-OCT uses a simultaneous polarization-sensitive four-channel detection scheme, four OCT images could be obtained simultaneously, which forms Jones matrix tomography. Furthermore, in our scanning protocol, four B-scans were performed at a single location, so we obtained four Jones matrices at a single location. From these four Jones matrices, a MF-OCT image set—structural OCT, power Doppler tomography, cumulative phase retardation, and DOPU images—was obtained. In particular, structural OCT was obtained by coherent averaging of 16 elements of four Jones matrices with adaptive phase offset correction, 46 which provided structural tomography similar to conventional OCT. For power Doppler imaging, first, three Doppler phase-shift images were obtained by a phase difference between four successive B-scans where each B-scan was a coherent average of four Jones elements of the OCT system. Then the three complex OCT images with Doppler phase were further complex-averaged to improve sensitivity. Power Doppler OCT was then defined as the squared power of the phase of the complex averaged image, and it formed a Doppler OCA image. For cumulative phase retardation imaging, the birefringence of the OCT system was numerically corrected. 4447 For DOPU, Stokes parameters were numerically obtained from the measured Jones matrix of a single polarization state of the probe beam, and the DOPU value was obtained from the kernel of 8 A-lines times 3 pixels depth. Degree of polarization uniformity was calculated with all Stokes parameters in the kernel. In a DOPU image, DOPU values only at pixels with OCT intensity more than 8 dB from the noise floor are displayed. The pixels with a lower OCT signal are masked and displayed as black. More technical details of this MF-OCT are described elsewhere. 46 With a single scan of the eye, MF-OCT provides tissue structure (structural OCT), vasculature (Doppler OCA), birefringence (cumulative phase retardation), and RPE-discriminable (DOPU) cross sections. 
For the MF-OCT measurement, the 6.0- × 6.0-mm area around the pathologic region was scanned with 512 A-lines (horizontal) × 4 frames (multiple scan) × 256 B-scans (vertical) in 6.6 seconds. 
Figure 1 shows typical MF-OCT images, including en face projections of structural OCT (Fig. 1a) and Doppler OCA (Fig. 1b) and MF-OCT cross sections of structural OCT (Fig. 1c), Doppler OCA (Fig. 1d), cumulative phase retardation (Fig. 1e), and DOPU (Fig. 1f), obtained from a normal macula of a 27-year-old Chinese male. An OCT en face image (Fig. 1a) showed the retinal vasculature, and a Doppler OCA image (Fig. 1b) showed the retinal and choroidal vasculature. A set of MF-OCT cross sections was extracted, as shown in Figures 1c through 1f from near the fovea (indicated with dotted yellow lines in Figs. 1a, 1b). Red arrows indicate the retinal vessels; they appeared with hyperscattering in structural OCT (Fig. 1c), nonzero power Doppler signals (Fig. 1d), no phase retardation (Fig. 1e), and high DOPU values (Fig. 1f). The yellow arrow indicates the RPE level. Retinal pigment epithelium is the bottom-most layer among three hyperscattering layers between the retina and choroid, and it is clearly visualized in the DOPU image as shown in Figure 1f. Because of the polarization scrambling property of melanin granules in the RPE, 39,40 the RPE appears with low DOPU values, which are generally less than 0.7 38 and appear with a yellowish-green color in the DOPU image, while other retinal tissues have high DOPU 38 values (close to the red color in the DOPU image and generally larger than 0.9). Because the choroid also includes melanin, 48 some part of the choroid also shows low DOPU values. White arrows indicate the location of the chorio-scleral interface (CSI), and the birefringence of the sclera induces an increase in phase retardation. 
Figure 1
 
Left macula images of a 27-year-old man who did not have an ocular disorder investigated with MF-OCT. (a) OCT en face image, (b) Doppler OCA, and cross sections of (c) OCT, (d) Doppler, (e) cumulative phase retardation, and (f) DOPU. Dotted yellow lines in (a) and (b) indicate the location of (cf). Scale bars: 0.5 mm (a, c)
Figure 1
 
Left macula images of a 27-year-old man who did not have an ocular disorder investigated with MF-OCT. (a) OCT en face image, (b) Doppler OCA, and cross sections of (c) OCT, (d) Doppler, (e) cumulative phase retardation, and (f) DOPU. Dotted yellow lines in (a) and (b) indicate the location of (cf). Scale bars: 0.5 mm (a, c)
Because MF-OCT provides a vast amount of information, including structural OCT, Doppler, cumulative phase retardation, and DOPU volumes, we designed a MF-OCT data browser for convenience of monitoring, as shown in Figure 2. It consists of en face projection images of structural OCT and en face Doppler OCA in the left column, and cross-sectional images of structural OCT, power Doppler, cumulative phase retardation, and DOPU displayed in the middle and right columns. An operator is allowed to quickly find the point of pathology in the en face images. By pointing to the position of pathology in the en face images with a line cursor, corresponding MF-OCT cross sections are displayed in the middle and right columns. Hence the operator can utilize both the structural OCT projection and en face OCA to quickly find the pathologic region. This simultaneous usage of structural projection and en face OCA reduces the risk of overlooking pathologies in comparison to conventional OCT. The operator is also allowed to mark up one of the cross-sectional images. In marking up an image, coregistered marks simultaneously appear at the same locations in the other cross-sectional images. This function enables quick coregistration of structural, Doppler, cumulative phase retardation, and DOPU findings. By using a well-designed data browser, such as this MF-OCT browser, the operator can quickly and effectively review a large amount of information provided by MF-OCT. 
Figure 2
 
Screen shot of a custom-made MF-OCT data browser. The OCT en face image and Doppler OCA are displayed in the left column, and cross-sectional images of structural OCT, power Doppler, cumulative phase retardation, and DOPU are displayed in the middle and right columns. By pointing to the position of interest in the en face images using a red line cursor, the corresponding cross-sectional MF-OCT images are simultaneously displayed in the middle and right columns. The operator can mark up one of the cross sections, and the same mark simultaneously appears at the same position in the other cross sections.
Figure 2
 
Screen shot of a custom-made MF-OCT data browser. The OCT en face image and Doppler OCA are displayed in the left column, and cross-sectional images of structural OCT, power Doppler, cumulative phase retardation, and DOPU are displayed in the middle and right columns. By pointing to the position of interest in the en face images using a red line cursor, the corresponding cross-sectional MF-OCT images are simultaneously displayed in the middle and right columns. The operator can mark up one of the cross sections, and the same mark simultaneously appears at the same position in the other cross sections.
For volumetric visualization, three MF-OCT volumetric images of structural OCT, power Doppler, and DOPU were integrated into a single volume with different colors—gray, orange, and green, respectively—as shown later in case 4 of the Results section. The volumetric rendering of three-dimensional (3-D) MF-OCT data was performed using commercial 3-D data visualization software, AMIRA 5.4.1 (FEI Visualization Sciences Group, Burlington, MA, USA). For the sake of 3-D visualization of RPE integrity with DOPU, a threshold was applied and DOPU values that were less than 0.7 were displayed in order to visualize the normal RPE that contains melanin granules. Hence, in the integrated volume rendering of MF-OCT, a green color at the RPE level is regarded as normal RPE, and a gray color at the RPE level is regarded as abnormal RPE. 
Results
Case 1: AMD With Ranibizumab Injection
Figures 3 and 4 show a case of AMD with minimally classic CNV (subject 1). The subject was a 68-year-old man treated with three monthly intravitreal ranibizumab injections (IVR). The first MF-OCT examination was performed 2 days before the first IVR. The second MF-OCT examination was performed 68 days after the third IVR. 
Figure 3
 
Right macular images of a 68-year-old man with AMD taken 2 days before the first IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 3
 
Right macular images of a 68-year-old man with AMD taken 2 days before the first IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 4
 
Right macular images of the same patient as in Figure 3. MF-OCT was performed 68 days after the third IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase) (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 4
 
Right macular images of the same patient as in Figure 3. MF-OCT was performed 68 days after the third IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase) (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 3 summarizes the first ophthalmic and MF-OCT examinations of subject 1. Figures 3a, 3b, 3c, and 3f represent the color fundus, ICGA (midphase), FA (late phase), and FAF images, respectively, corresponding to the area of the MF-OCT examination. Choroidal neovascularization was observed in the midphase of ICGA, as indicated by an arrow in Figure 3b, and it was surrounded by a dark rim. The late phase of FA (Fig. 3c) showed leakage around the CNV location, which indicated that the CNV was in an active state. The color fundus image (Fig. 3a) showed a moderate bright appearance around the CNV location. 
An abnormal structure with RPE elevation and exudation was observed in structural OCT (Fig. 3g), as indicated by a dashed circle. Doppler signals were observed in this abnormal structure, as indicated by arrows in a Doppler cross section (Fig. 3h). It was found that these Doppler signals were connected to the choroid areas. It could be that artifacts occurred due to increased phase variance below the abnormal vessels, or the results could be real Doppler signals from abnormal choroidal vessels. In structural OCT, the RPE was not clearly delineated in the exudates because of the similar scattering properties of the RPE and exudation and an unclear boundary between them. On the other hand, the RPE was clearly and selectively visualized as a low DOPU region (yellow to green) in a DOPU cross section (Fig. 3i). Hence, this region can be interpreted as abnormal Doppler signals representing the CNV, which stretched from the choroid and penetrated into the exudation region through the RPE defect. These cross-sectional observations are well matched with the leakage in FA (Fig. 3c) around the CNV. 
This kind of RPE corruption buried in exudates was observed in seven eyes of six cases, including one AMD case before and after treatment, four eyes with PCV before treatment, and one eye with PCV after treatment. Here, discrimination of RPE and exudation was successfully achieved with DOPU cross sections for all cases, while it was not easy to discriminate them with structural OCT imaging. 
Even without structural RPE corruption, RPE damage was observed with DOPU imaging (Fig. 3i) on the right side of the cross-section images, as indicated by arrowheads in Figures 3g through 3i. Structural OCT (Fig. 3g) showed more hyperpenetration into the choroid at this region compared with the other regions in this image. At the corresponding location (arrowhead in Fig. 3f) in the FAF image, low autofluorescence was observed without blockage. These observations consistently suggested RPE damage in this region. 
Doppler OCA (Fig. 3e) shows a similar appearance to the midphase of ICGA (Fig. 3b), including the CNV. Abnormal Doppler signals were observed at the CNV location and were surrounded by hypo-Doppler signals as indicated with arrows in Figure 3e. This finding is consistent with our previous study. 29 The OCT en face image (Fig. 3d) showed a pattern similar to that of the color fundus image around the CNV location; however, the appearance was slightly different. Specifically, the OCT en face image showed low scattering intensity at the CNV location, while the color fundus image showed a bright appearance. 
Figure 4 summarizes the second ophthalmic and MF-OCT examinations of subject 1, with figure parts presented in the same order as in Figure 3. After three IVR treatments, the CNV was still observed from the midphase of the ICGA image (red arrow in Fig. 4b), but it was surrounded by a discontinuous dark rim (white arrows in Fig. 4b). Doppler OCA (Fig. 4e) showed an appearance similar to that of the midphase of ICGA including hyper-Doppler signals at the CNV region (red arrow in Fig. 4e), which was also surrounded by discontinuous hypo-Doppler signals (white arrows in Fig. 4e). 
The color fundus image showed exudation with a bright white region at the location of the CNV (red arrow in Fig. 4a). The OCT en face image (Fig. 4d) also showed hyperscattering OCT signals at the same location, and its shape was similar to that of the white region in the color fundus image. Figures 4g through 4i are MF-OCT cross sections that were created from the same dataset with Figures 4d and 4e. Retinal detachment and edema were not observed in the structural OCT image, but RPE deformation still existed. Around the deformed RPE, Doppler signals were observed at abnormal positions, that is, above the Bruch's membrane contour (dashed line in Figs. 4g, 4h) and beneath the deformed RPE layer, as indicated by red arrows in Figures 4g and 4h. 
The late phase of FA showed staining at the location of the CNV without leakage (yellow arrow in Fig. 4c). The DOPU cross section clearly discriminated RPE deformation and exudation around the CNV (white arrow in Fig. 4i), which was not clear in the structural OCT intensity cross section. 
Case 2: Idiopathic Neovascular Maculopathy
Figure 5 introduces a case of idiopathic neovascular maculopathy with predominantly classic CNV (subject 2). The subject was a 43-year-old man. Choroidal neovascularization surrounded by a dark rim was observed in the midphase of ICGA, as indicated by an arrow in Figure 5b. Leakage was observed in the late phase of FA around the CNV location, as indicated by an arrow in Figure 5c. The color fundus image (Fig. 5a) showed a moderate bright appearance around the CNV location. 
Figure 5
 
Left macular images of a 43-year-old man with neovascular maculopathy. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 5
 
Left macular images of a 43-year-old man with neovascular maculopathy. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
An OCT en face image (Fig. 5d) showed an appearance similar to that of the color fundus image around the CNV location, as indicated by a red arrow. A set of MF-OCT cross-section images (Figs. 5g–5i) was extracted at the CNV location (dotted yellow lines in Figs. 5d–5f). An RPE elevation was observed inside the retinal detachment in a structural OCT cross section (Fig. 5g) and appeared with hyperscattering, as indicated by a red circle. 
Abnormal Doppler signals were observed inside the RPE elevation, as indicated by a red circle in a power Doppler cross section (Fig. 5h). These Doppler signals were connected to the choroid areas; hence, these Doppler signals might represent an abnormal choroidal vasculature that was generated beneath the RPE. Doppler OCA (Fig. 5e) showed a vascular appearance similar to that of the midphase of ICGA, including hyper-Doppler signals (red arrow in Fig. 5e) at the CNV location and hypo-Doppler signals at a dark-rim location. 
In structural OCT cross section (Fig. 5g), the RPE still seemed well delineated; however, in DOPU cross section (Fig. 5i), the upper part of the elevated RPE showed high DOPU values. This might represent a RPE defect, and this location was well matched with hypoautofluorescence in FAF (yellow arrow in Fig. 5f). Fundus autofluorescence images represent RPE integrity by autofluorescence of lipofuscin in the RPE. In this case series, 6 of 12 eyes showed hypoautofluorescence regions, and these regions were collocated with the regions where the RPE level showed high DOPU values, as exemplified in FAF and DOPU images of case 2 and case 4. These findings showed that the high DOPU values at the RPE level represented RPE damage. 
Case 3: PCV
Figure 6 introduces a case of end-stage PCV with a disciform scar (subject 5). The subject was an 80-year-old man. The color fundus image (Fig. 6a) showed a fibrotic lesion on the macula. This fibrotic lesion appeared with hyperscattering in an OCT en face image (Fig. 6d). 
Figure 6
 
Left macular images of an 80-year-old man with PCV. (a) Color fundus photograph, (b) midphase ICGA, (c) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (f, k) cumulative phase retardation, (g, j) OCT, (h) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (fi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 6
 
Left macular images of an 80-year-old man with PCV. (a) Color fundus photograph, (b) midphase ICGA, (c) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (f, k) cumulative phase retardation, (g, j) OCT, (h) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (fi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
The midphase of ICGA (Fig. 6b) and Doppler OCA (Fig. 6e) showed similar vasculatures, and a set of MF-OCT cross sections (Figs. 6f–6i) was extracted at the location of a fibrotic lesion (dotted yellow lines in Figs. 6d, 6e). A cumulative phase retardation cross section showed a rapid retardation alteration along the depth direction, as indicated by four free curves in Figure 6f. The alteration of cumulative phase retardation is an indicator of birefringent tissue. Since scars with fibrosis are known to be birefringent and to alter cumulative phase retardation, 42,49 this appearance indicates scarring at this region. This kind of disciform scar was observed in two cases of PCV. The four indicators of free curves, which indicate the boundaries of fibrotic lesions, were coregistered in structural OCT, power Doppler, and DOPU cross sections as shown in Figures 6g through 6i, respectively. These fibrotic lesions appeared inside the exudation region. Abnormal Doppler signals were observed beneath the fibrotic lesion as indicated by dashed circles in Figures 6f through 6i. A vessel, indicated with a yellow arrow in Figures 6b and 6e, corresponded to the abnormal Doppler signals (dashed circle in Fig. 6h); hence, it can be regarded as an abnormal choroidal vessel that stretched into the fibrosis. 
In the structural OCT en face image (Fig. 6d) and color fundus photograph (Fig. 6a), some choroidal vessels were clearly detected around the pathologic regions (as indicated by dashed circles). A set of MF-OCT cross sections (Figs. 6j–6l: structural OCT, cumulative phase retardation, and DOPU) showed different penetrations in structural OCT and cumulative phase retardation among three regions labeled r1 through r3. Region r1 is a relatively normal region. In this region, the RPE appeared with low DOPU values as usual 38 due to a high concentration of melanin granules. The choroid appeared with low DOPU values. This may indicate that the choroid in this region contains some amount of melanin. In region r2, high DOPU values were observed at the position where the RPE was expected according to structural OCT, perhaps due to the loss of melanin; but the choroid showed some low DOPU values, so it still contained some amount of melanin. In region r3, high DOPU values were found at the RPE and choroid. This would indicate significant loss of melanin at the RPE and, therefore, RPE damage. The melanin in the choroid was also lost. The different melanin amounts in r1 through r3 were well matched with different penetrations and scattering intensities, as observed in Figure 6j. These kinds of localized hyperpenetrations were observed in seven eyes of six PCV cases. 
Case 4: PCV Treated With Combined IVR and PDT
Figures 7 through 10 introduce another case of PCV (subject 6). The subject was a 58-year-old man who was treated with combined IVR and photodynamic therapy (PDT). The first MF-OCT examination was performed 15 days before the combination therapy, and the second MF-OCT examination was performed 118 days after the combination therapy. 
Figure 7
 
Right macular images of a 58-year-old man with PCV taken before treatment. (a) Color fundus, (b) midphase of ICGA, (c) late phase of FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) OCT, (h, k) power Doppler, and (i, l) DOPU. Yellow and red arrow pairs in (df) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 7
 
Right macular images of a 58-year-old man with PCV taken before treatment. (a) Color fundus, (b) midphase of ICGA, (c) late phase of FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) OCT, (h, k) power Doppler, and (i, l) DOPU. Yellow and red arrow pairs in (df) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
A large crescent-shaped hemorrhage was observed in the color fundus image (Fig. 7a) on the inferior side of the pigment epithelial detachment (PED). The midphase of ICGA (Fig. 7b) showed PED with hypofluorescence, and BVN with polypoidal lesions (red arrow) was observed in the upper part of the PED. Leakage was observed at the location of the BVN in the late phase of FA (Fig. 7c), as indicated by a red arrow. The OCT en face image (Fig. 7d) showed a well-delineated boundary of the PED with hyperscattering signals. This may be due to the steeply elevated RPE at the perimeter of the PED as shown in OCT cross sections (Figs. 7g, 7j). Doppler OCA (Fig. 7e) showed abnormal Doppler signals at the location of the BVN as indicated by arrows. Two sets of cross sections (Figs. 7g–7i at the position of the yellow arrow pairs in Figs. 7d–7f; Figs. 7j–7l at the red arrow pairs) were extracted from the BVN location. In cross sections of Figures 7g through 7i, Doppler signals were observed beneath the PED (circles in Figs. 7g–7i). We interpret these Doppler signals as the vasculature of polyps based on the location in depth and the similar appearance to ICGA. This interpretation agreed well with the findings in the literature on OCT imaging of PCV. 15,16 The RPE appeared with low DOPU values over the entire region including the PED (Fig. 7i). In cross sections of Figures 7j through 7l, abnormal Doppler signals were observed beneath the PED. The expected RPE region above the abnormal Doppler signals, however, showed high DOPU values, which indicated that the RPE was damaged (circles in Figs. 7j–7l). This location was well matched with the location of RPE damage in the FAF (red arrow in Fig. 7f). 
It was found that the locations of FA leakage were well correlated with the locations where the RPE appeared with high DOPU values near the abnormal Doppler signals. This might represent the RPE damage by active abnormal choroidal vasculature. Fluorescence angiography images were taken from nine eyes of seven cases, including one eye with AMD before and after treatment, one eye with idiopathic neovascular maculopathy, five eyes with PCV before treatment, and one eye with PCV after treatment. Leakage was observed in all seven cases before treatment as exemplified in Figures 3c and 7c, and the high DOPU values at the RPE level above abnormal Doppler signals were observed at the FA leakage locations as exemplified in Figures 7k and 7l. One AMD case (Figs. 3g–3i) was an exceptional case in which RPE was penetrated by CNV as described in Results, case 1. It should be noted that MF-OCT does not visualize leakage directly. However, the lateral locations that showed abnormal Doppler signals and high DOPU values at the RPE level were found to be well correlated with the locations of FA leakage. 
Figure 8 shows a volumetric MF-OCT image set generated from the same data as in Figure 7; structural OCT, power Doppler, and DOPU volumes were rendered with gray, orange, and green colors, respectively. For DOPU volume, DOPU values less than 0.7 are displayed. Figures 8a and 8b show fly-through MF-OCT volumes sectioned at the same locations as in Figures 7g through 7i and Figures 7j through 7l, respectively. These MF-OCT volumetric images more clearly show the clinical findings observed at each type of MF-OCT cross section (Figs. 7g–7l). Doppler signals observed beneath the PED (red arrows) were abnormal, and they represented the BVN of the PCV. Hyperscattering regions (white arrowheads) between the PED and retina are abnormal structures. These regions do not show Doppler signals and low DOPU values. Similar Doppler and DOPU appearance was found in the exudates of other cases in this study. Hence, these regions would represent exudates. Some parts at the RPE level did not show low DOPU values between the two yellow bars in Figure 8b, while the bottom-most hyperscattering layer of the PED generally appeared with low DOPU values as indicated by yellow arrows in Figures 8a and 8b. This means that the RPE above the abnormal choroidal vessels was damaged. This interpretation is well matched with observations from ICGA, FA, and FAF. 
Figure 8
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 7. (a, b) Fly-through rendered volumes cross-sectioned at the locations of Figures 7g through 7i and Figures 7j through 7l, respectively. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For DOPU volume, DOPU values less than 0.7 are displayed. (cf) The whole rendered volumes; (c) combined volume of structural OCT, power Doppler, and low DOPU values, (d) combined volume without structural OCT, (e) power Doppler signal, and (f) low DOPU values.
Figure 8
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 7. (a, b) Fly-through rendered volumes cross-sectioned at the locations of Figures 7g through 7i and Figures 7j through 7l, respectively. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For DOPU volume, DOPU values less than 0.7 are displayed. (cf) The whole rendered volumes; (c) combined volume of structural OCT, power Doppler, and low DOPU values, (d) combined volume without structural OCT, (e) power Doppler signal, and (f) low DOPU values.
Figure 8c shows a combined volume of structural OCT, power Doppler, and DOPU. The structural OCT is displayed with a semitransparent gray, which makes the underlying layer visible. Figures 8d through 8f are the same rendered volumes as in Figure 8c, respectively, but without structural OCT (Fig. 8d); these show only power Doppler signals, which represent the vasculature (Fig. 8e), and only the low DOPU region, which represents the normal RPE (Fig. 8f). As indicated by dashed circles in Figures 8d through 8f, the 3-D anatomy of the BVN located beneath the PED and the damaged RPE above the BVN are clearly visualized. It should be noted that the area with missing RPE (indicated by arrowheads in Fig. 8f) is an artifact caused by strong signal attenuation due to the thick exudaion above the RPE. 
Figure 9 summarizes the MF-OCT images at 118 days after the combination therapy; figure parts are presented in the same order as in Figure 7. The crescent-shaped hemorrhage shown in Figure 7 was not observed after the treatment. However, U-shaped exudation (indicated with white arrowheads in Figs. 9a, 9f) was observed in color fundus photography (Fig. 9a) and FAF (Fig. 9f) with bright white color and hyperautofluorescence, respectively. An OCT en face image (Fig. 9d) showed a similar appearance of U-shaped exudation as in the color fundus image, and both were caused by hyperscattering. A Doppler en face image (Fig. 9e) showed a similar U-shaped appearance as in the midphase ICGA, and both were caused by blockage of choroidal vessel flow signals due to exudation. 
Figure 9
 
Right macular images from the same PCV subject as in Figures 7 and 8. Images were taken after a treatment with ranibizumab and PDT. (a) Color fundus, (b) midphase ICGA, (c) late-phase FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) structural OCT, (h, k) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 9
 
Right macular images from the same PCV subject as in Figures 7 and 8. Images were taken after a treatment with ranibizumab and PDT. (a) Color fundus, (b) midphase ICGA, (c) late-phase FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) structural OCT, (h, k) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Abnormal choroidal vessels (yellow arrow in Fig. 9b) were still observed from the midphase of ICGA, and polypoidal lesion was regressed. Doppler OCA (Fig. 9e) showed a similar vasculature pattern as in the midphase of ICGA including abnormal choroidal vessels. A set of the MF-OCT cross sections (Figs. 9g, 9i) was extracted from the location of residual abnormal choroidal vessels (yellow lines in Figs. 9d, 9e). Abnormal Doppler signals were observed beneath the PED in the power Doppler image, and partial damage of the RPE above the abnormal vessels was observed in the DOPU image (circles in Figs. 9g–9i). 
A lesion with a window defect was observed in FA (red arrow in Fig. 9c), and this lesion showed hypoautofluorescence in FAF (red arrow in Fig. 9f). A set of MF-OCT cross sections (Figs. 9j–9l) was extracted from the corresponding location (red lines in Figs. 9d, 9e). Significant abnormalities were not observed in structural OCT (circle in Fig. 9j) and power Doppler (circle in Fig. 9k) cross sections; however, a DOPU cross section showed high DOPU values at the location of the window defect (circle in Fig. 9l), which represented RPE damage. 
Figure 10 is a volumetric MF-OCT image set generated from the same data as in Figure 9, but the clinical finding was more intuitively visualized than in Figure 9. Figures 10a and 10b are fly-through cross-sectional volumes of MF-OCT, which are sectioned at the same locations as in Figures 9g through 9i and Figures 9j through 9l, respectively. Residual abnormal choroidal vessels were observed with hyper-Doppler signals beneath the PED as indicated by a red arrow in Figure 10a. By comparing the appearance of the RPE at other regions (indicated by yellow arrow), such as that indicated by the yellow arrowhead, it was found that the RPE above the abnormal choroidal vessels was damaged. Figure 10b assists with easy observation of exudation (white arrowheads) above the RPE and damaged RPE (between two yellow bars). 
Figure 10
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 9. Fly-through cross-sectioned volumes around (a) abnormal choroidal vessels, (b) exudation and RPE damage. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For the DOPU volume, DOPU values less than 0.7 are displayed. Volumetric rendering of (c) the entire volume in which structural OCT is displayed with semitransparent gray color, (d) power Doppler and low DOPU values, and (e) low DOPU values.
Figure 10
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 9. Fly-through cross-sectioned volumes around (a) abnormal choroidal vessels, (b) exudation and RPE damage. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For the DOPU volume, DOPU values less than 0.7 are displayed. Volumetric rendering of (c) the entire volume in which structural OCT is displayed with semitransparent gray color, (d) power Doppler and low DOPU values, and (e) low DOPU values.
Figure 10c is a 3-D rendering of the entire volume of Figures 10a and 10b, where structural OCT was rendered with a semitransparent gray color. The volumetric U-shaped exudation (white arrowheads) was observed under the retinal vasculature. Figure 10d shows the same rendered volume as in Figure 10c but without structural OCT. Some choroidal vessels were observed in the dashed circle region due to hyperpenetration caused by RPE damage. The RPE damaged region found in the MF-OCT volume was nearly collocated to the location of the window defect in FA images (red arrow in Fig. 9c). 
Abnormality-Detection Ability of MF-OCT
Figure 11 summarizes the comparison of MF-OCT findings and ophthalmic images of RPE damage. Figure 11 shows the color fundus image (Figs. 11a1–a3), late phase of FA (Figs. 11b1–b3), FAF (Figs. 11c1–c3), top-view image of DOPU volume (Figs. 11d1–d3), and power Doppler and DOPU registered volume (Figs. 11e1–e3) of case 2 (Figs. 11a1–e1), case 4 before treatment (Figs. 11a2–e2), and case 4 after treatment (Figs. 11a3–e3). Yellow arrows indicate low autofluorescence in FAF, and RPE damage was observed in DOPU images, as shown in Figures 11d1 through 11e3. Case 4 with PCV showed interesting changes after treatment. Before treatment, RPE damage was observed with DOPU imaging at the BVN location, as indicated by dashed circles in Figures 11b2, 11d2, and 11e2. Near the BVN, where hyperfluorescence signals were observed in the late phase of FA, RPE damage was also observed with DOPU imaging, as indicated by white circles in Figures 11b2, 11b3, and 11d2 through 11e3. The window defect lesion in FA was detected after treatment (red circles in Figs. 11d3–11e3), and RPE damage was visualized by DOPU imaging at the corresponding location. However, the damaged region of the RPE in the DOPU image was wider than that of the window defect in FA. 
Figure 11
 
Comparison of the color fundus image (a1a3), late phase of FA (b1b3), FAF (c1c3), top-view images of DOPU volume (d1d3), and power Doppler and DOPU registered volume (e1e3). From the left-side column, case 2 (a1e1), case 4 before treatment (a2e2), and case 4 after treatment (a3e3).
Figure 11
 
Comparison of the color fundus image (a1a3), late phase of FA (b1b3), FAF (c1c3), top-view images of DOPU volume (d1d3), and power Doppler and DOPU registered volume (e1e3). From the left-side column, case 2 (a1e1), case 4 before treatment (a2e2), and case 4 after treatment (a3e3).
To evaluate the abnormality-detection ability of MF-OCT, we performed a grading-based comparison between abnormalities found with MF-OCT and other standard ophthalmic images. A grader (Y-JH) identified abnormalities in each case based on the cross-sectional MF-OCT images and marked them on the OCT and Doppler en face projection images. Another grader (MM), who is an experienced ophthalmologist, identified the abnormalities in each case based on standard ophthalmic images, color fundus, ICGA, FA, FAF, and standard OCT images (3D OCT-2000; Topcon Corp., Tokyo, Japan), which were used for actual clinical diagnosis. These two grading results from MF-OCT and standard ophthalmic images are denoted as test outcomes and reference outcomes, respectively. 
The identified abnormalities were RPE damage, abnormal choroidal vasculature, hard exudates, and fibrosis. The marking criteria for reference outcomes were as follows. Retinal pigment epithelium damage was identified with low autofluorescence in FAF unless blockage was found in the color fundus image, ICGA, or FA. Abnormal choroidal vasculature was identified with FA or ICGA time series images. Hard exudates were identified with bright white signals in the color fundus image and intraretinal hyperscattering spots in standard OCT images. Fibrosis was identified with bright white signal in the color fundus image, and a hyperscattering mass around the RPE was found in standard OCT images. The marking criteria for test outcomes were as follows. Retinal pigment epithelium damage was identified when the RPE expected level appeared with high DOPU values and hyperscattering intensity in OCT images. When the RPE layer location was not clear in the OCT intensity images, it was not identified as RPE damage even though it appeared with high DOPU values. Abnormal choroidal vasculature was identified when the Doppler signals were observed between elevated RPE and Bruch's membrane contour or above the RPE and deformed retinal layer. Hard exudates were identified when the intraretinal hyperscattering spots were observed in OCT images and when they appeared with low DOPU values without significant Doppler signals. Fibrosis was identified when the localized phase retardation increase was observed in an abnormal structure. 
The agreement between abnormalities found with MF-OCT (test outcomes) and ophthalmic images (reference outcomes) was examined. The abnormality-detection sensitivity of MF-OCT was defined as the number of abnormalities identified in both the test outcomes and the reference outcomes divided by the number of abnormalities identified in reference outcomes. The ratio between the number of abnormalities found only in test outcomes over the total number of abnormalities found in the test outcomes or reference outcomes was also calculated and denoted as the “specific detection rate.” This rate was used as an alternative to a specificity that cannot be defined in this study because the number of true negatives cannot be defined. For these computations, when a single abnormality in one of the reference outcome or test outcome images corresponded to multiple abnormalities in the other image, its number of abnormalities was counted as multiple abnormalities. Table 2 summarizes the sensitivities and specific detection rates. 
Table 2
 
Abnormality-Detection Test With MF-OCT
Table 2
 
Abnormality-Detection Test With MF-OCT
RPE Damage Abnormal Choroidal Vasculature Hard Exudates Fibrosis
Sensitivity 0.92 0.95 0.56 0.50
Specific detection rate 0.73 0.13 0.18 0.33
In the case of RPE damage detection, sensitivity was high, but the specific detection rate that is an alternative to a false-positive rate was also high. However, it should be noted that this high detection rate does not necessarily indicate low specificity of MF-OCT. It can be interpreted as MF-OCT identifying RPE damage more sensitively than the standard ophthalmic images. For example, melanin loss might be a preindicator of RPE cell death, and it can be detected by DOPU imaging but cannot be detected by standard ophthalmic imaging. An extensive study to prove this superior detection power of MF-OCT is a potential for the future. 
For abnormal choroidal vasculature detection, the sensitivity was high and the specific detection rate was low. This is in good agreement with our observation that the appearances of the vasculature in Doppler en face images and midphase of ICGA are similar to each other. 
In the case of hard exudates, sensitivity was moderate and the specific detection rate was relatively low. The moderate sensitivity is mainly caused by many small-size hard exudates that were detected in standard ophthalmic images but not in MF-OCT images. Multifunctional OCT would have a limited ability to detect small exudates. 
In the case of fibrosis, both the sensitivity and specific detection rate were moderate. Since fibrosis was found only in three cases, it is difficult to come to a specific conclusion. 
According to these results, it is suggested that MF-OCT has superior detection capability for RPE damage and a capability to detect abnormal vessels comparable to that of standard ophthalmic imaging. On the other hand, the standard ophthalmic images showed a superior capability to detect hard exudates compared with MF-OCT. 
Discussion
In this study, we demonstrated vasculature and RPE-discriminable imaging of exudative macular diseases using MF-OCT. Multifunctional OCT provided four different contrast images: structural OCT, power Doppler, cumulative phase retardation, and DOPU values. The structure, vasculature, tissue birefringence, melanin concentration, and RPE integrity were visualized by these contrasts. 
The en face power Doppler OCA was found to provide similar images to the midphase of ICGA. Abnormal Doppler signals were observed in all cases as exemplified in Figures 3e, 4e, 5e, 6e, and 7e and Figure 9e. Their appearance in Doppler OCA images corresponded well with the vasculature images of midphase ICGA, as exemplified in Figures 3b and 3e through Figures 9b and 9e. 
Structural OCT en face projection images could be utilized for rapid screening of abnormalities. Localized hyperscattering was observed in OCT en face images at the region of exudation or RPE deformation because an extended hyperscattering along the depth existed at these regions. These regions were also easily recognizable in OCT cross sections because of the clear morphological abnormality. Furthermore, the hyperpenetration location appeared as localized hyperscattering in OCT en face images. In these hyperpenetration regions, high DOPU values appeared at the RPE level or choroid, as exemplified in Figures 6l and 9l. Because the high DOPU values are known to be an indicator of loss of melanin granules, 39,40 the RPE and choroid at these regions are considered to have fewer melanin granules than other regions. This reduction of melanin granules can be the cause of hyperpenetration. 
Discrimination of the RPE and exudation is available with DOPU values. Exudation was observed in eight eyes of six cases, including one AMD case before and after treatment, five eyes with PCV before treatment, and one eye with PCV after treatment. Except for one case (subject 6, before treatment), delineation of the RPE from exudation was not possible at the exudative regions in structural OCT cross sections, as shown in Figures 3g, 4g, 6g, and 9j. On the other hand, the RPE was discriminated from exudation in DOPU cross sections, because exudation normally shows high DOPU values while normal RPE shows low DOPU values, as shown in Figures 3i, 4i, 6i, and 9l. It should be noted that DOPU-based discrimination is available only when the RPE tissue is normal enough to contain melanin granules. If the RPE cells are damaged and lose their melanin granules, the RPE appears with high DOPU values. Although it has been reported that the melanin content in RPE cells decreases with aging 5052 and photodamage, 51,52 similar melanin reduction by exudative macular diseases has not been well investigated. Multifunctional OCT can be used to further investigate this kind of possible RPE degeneration. 
In this study, MF-OCT demonstrated the various features of exudative macular disease. Doppler OCA could provide 3-D vasculature images, and PS-OCT could provide useful information about the microstructure of exudative lesions that could not be provided by conventional intensity-based OCT. This multifunctional imaging would become an additional modality to complement conventional ophthalmic examinations. The observations obtained from the current study will provide good starting points for more extensive studies to validate the utility of MF-OCT. Conventional ophthalmic examinations require independent measurement protocols and thus require a relatively long time to obtain a set of investigative images. In the case of angiography, dye injection requires a complicated process and is uncomfortable for the patient. In contrast, MF-OCT provides comprehensive ophthalmic examination with reduced measurement time and effort. In addition, it is noninvasive. Interpretation of a MF-OCT examination was well matched with that for conventional ophthalmic examinations. These results suggest that MF-OCT would have the potential to provide extended information for ophthalmic diagnosis. 
Acknowledgments
Supported in part by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grants 11J01600 and 24592682. 
Disclosure: Y.-J. Hong, Topcon Corp. (F), Tomey Corp. (F), Nidek (F); M. Miura, Novartis (C), Bayer (C); M.J. Ju, None; S. Makita, Topcon Corp. (F), Tomey Corp. (F), Nidek (F), P; T. Iwasaki, None; Y. Yasuno, Topcon Corp. (F), Tomey Corp. (F), Nidek (F), P 
References
Yannuzzi LA. The Retinal Atlas . Philadelphia: Saunders/Elsevier; 2010: 544–591.
Bressler NM Bressler SB Fine SL. Age-related macular degeneration. Surv Ophthalmol . 1988; 32: 375–413. [CrossRef] [PubMed]
Age-Related Eye Disease Study Research Group. Risk factors associated with age-related macular degeneration: a case-control study in the age-related eye disease study: age-related eye disease study report number 3. Ophthalmology . 2000; 107: 2224–2232. [CrossRef] [PubMed]
Mariotti SP. Global Data on Visual Impairments 2010. Geneva: World Health Organization. Available at: http://www.who.int/blindness/GLOBALDATAFINALforweb.pdf. Accessed 2012.
Yannuzzi LA Wong DWK Sforzolini BS Polypoidal choroidal vasculopathy and neovascularized age-related macular degeneration. Arch Ophthalmol . 1999; 117: 1503–1510. [CrossRef] [PubMed]
Tsujikawa A Sasahara M Otani A Pigment epithelial detachment in polypoidal choroidal vasculopathy. Am J Ophthalmol . 2007; 143: 102–111. [CrossRef] [PubMed]
Moshfeghi DM Blumenkranz MS. Role of genetic factors and inflammation in age-related macular degeneration. Retina . 2007; 27: 269–275. [CrossRef] [PubMed]
Hata Y Nakagawa K Sueishi K Ishibashi T Inomata H Ueno H. Hypoxia-induced expression of vascular endothelial growth factor by retinal glial cells promotes in vitro angiogenesis. Virchows Arch . 1995; 426: 479–486. [CrossRef] [PubMed]
Ma W Lee SE Guo J RAGE ligand upregulation of VEGF secretion in ARPE-19 cells. Invest Ophthalmol Vis Sci . 2007; 48: 1355–1361. [CrossRef] [PubMed]
Kovach JL Schwartz SG Flynn HW Scott IU. Anti-VEGF treatment strategies for wet AMD. J Ophthalmol . 2012; 2012: 786870. [PubMed]
Papadopoulos N Martin J Ruan Q Binding and neutralization of vascular endothelial growth factor (VEGF) and related ligands by VEGF Trap, ranibizumab and bevacizumab. Angiogenesis . 2012; 15: 171–185. [CrossRef] [PubMed]
Yannuzzi LA Rohrer KT Tindel LJ Sobel R Costanza M. Fluorescein angiography complication survey. Ophthalmology . 1986; 93: 611–617. [CrossRef] [PubMed]
Hope-Ross M Yannuzzi LA Gragoudas ES Adverse reactions due to indocyanine green. Ophthalmology . 1994; 101: 529–533. [CrossRef] [PubMed]
Huang D Swanson E Lin C Optical coherence tomography. Science . 1991; 254: 1178–1181. [CrossRef] [PubMed]
Yasuno Y Miura M Kawana K Visualization of sub-retinal pigment epithelium morphologies of exudative macular diseases by high-penetration optical coherence tomography. Invest Ophthalmol Vis Sci . 2009; 50: 405–413. [CrossRef] [PubMed]
Kim JH Kang SW Kim T-H Kim SJ Ahn J. Structure of polypoidal choroidal vasculopathy studied by colocalization between tomographic and angiographic lesions. Am J Ophthalmol . 2013; 156: 974–980, e2. [CrossRef] [PubMed]
Chen Z Milner TE Dave D Nelson JS. Optical Doppler tomographic imaging of fluid flow velocity in highly scattering media. Opt Lett . 1997; 22: 64–66. [CrossRef] [PubMed]
White B Pierce M Nassif N In vivo dynamic human retinal blood flow imaging using ultra-high-speed spectral domain optical coherence tomography. Opt Express . 2003; 11: 3490–3497. [CrossRef] [PubMed]
Leitgeb RA Schmetterer L Hitzenberger CK Real-time measurement of in vitro flow by Fourier-domain color Doppler optical coherence tomography. Opt Lett . 2004; 29: 171–173. [CrossRef] [PubMed]
Leitgeb RA Schmetterer L Drexler W Fercher AF Zawadzki RJ Bajraszewski T. Real-time assessment of retinal blood flow with ultrafast acquisition by color Doppler Fourier domain optical coherence tomography. Opt Express . 2003; 11: 3116–3121. [CrossRef] [PubMed]
Baumann B Potsaid B Kraus MF Total retinal blood flow measurement with ultrahigh speed swept source/Fourier domain OCT. Biomed Opt Express . 2011; 2: 1539–1552. [CrossRef] [PubMed]
Makita S Hong Y Yamanari M Yatagai T Yasuno Y. Optical coherence angiography. Opt Express . 2006; 14: 7821–7840. [CrossRef] [PubMed]
Jaillon F Makita S Min E-J Lee BH Yasuno Y. Enhanced imaging of choroidal vasculature by high-penetration and dual-velocity optical coherence angiography. Biomed Opt Express . 2011; 2: 1147–1158. [CrossRef] [PubMed]
Hong Y-J Makita S Jaillon F High-penetration swept source Doppler optical coherence angiography by fully numerical phase stabilization. Opt Express . 2012; 20: 2740–2760. [CrossRef] [PubMed]
Miura M Makita S Iwasaki T Yasuno Y. An approach to measure blood flow in single choroidal vessel using Doppler optical coherence tomography. Invest Ophthalmol Vis Sci . 2012; 53: 7137–7141. [CrossRef] [PubMed]
Blatter C Klein T Grajciar B Ultrahigh-speed non-invasive widefield angiography. J Biomed Optics . 2012; 17: 070505-1–070505-3. [CrossRef]
Braaf B Vermeer KA Vienola KV de Boer JF. Angiography of the retina and the choroid with phase-resolved OCT using interval-optimized backstitched B-scans. Opt Express . 2012; 20: 20516–20534. [CrossRef] [PubMed]
Miura M Makita S Iwasaki T Yasuno Y. Three-dimensional visualization of ocular vascular pathology by optical coherence angiography in vivo. Invest Ophthalmol Vis Sci . 2011; 52: 2689–2695. [CrossRef] [PubMed]
Hong Y-J Miura M Makita S Noninvasive investigation of deep vascular pathologies of exudative macular diseases by high penetration optical coherence angiography. Invest Ophthalmol Vis Sci . 2013; 54: 3621–3631. [CrossRef] [PubMed]
Boulton M Różanowska M Wess T. Ageing of the retinal pigment epithelium: implications for transplantation. Graefes Arch Clin Exp Ophthalmol . 2004; 242: 76–84. [CrossRef] [PubMed]
Schmitz-Valckenberg S Fleckenstein M Scholl HPN Holz FG. Fundus autofluorescence and progression of age-related macular degeneration. Surv Ophthalmol . 2009; 54: 96–117. [CrossRef] [PubMed]
Querques L Querques G Forte R Souied EH. Microperimetric correlations of autofluorescence and optical coherence tomography imaging in dry age-related macular degeneration. Am J Ophthalmol . 2012; 153: 1110–1115. [CrossRef] [PubMed]
Elsner AE Weber A Cheney MC VanNasdale DA Miura M. Imaging polarimetry in patients with neovascular age-related macular degeneration. J Opt Soc Am A Opt Image Sci Vis . 2007; 24: 1468–1480. [CrossRef] [PubMed]
Hee MR Huang D Swanson EA Fujimoto JG. Polarization-sensitive low-coherence reflectometer for birefringence characterization and ranging. J Opt Soc Am B . 1992; 9: 903–908. [CrossRef]
De Boer JF Milner TE van Gemert MJC Nelson JS. Two-dimensional birefringence imaging in biological tissue by polarization-sensitive optical coherence tomography. Opt Lett . 1997; 22: 934–936. [CrossRef] [PubMed]
Yasuno Y Makita S Sutoh Y Itoh M Yatagai T. Birefringence imaging of human skin by polarization-sensitive spectral interferometric optical coherence tomography. Opt Lett . 2002; 27: 1803–1805. [CrossRef] [PubMed]
Yamanari M Makita S Madjarova VD Yatagai T Yasuno Y. Fiber-based polarization-sensitive Fourier domain optical coherence tomography using B-scan-oriented polarization modulation method. Opt Express . 2006; 14: 6502–6515. [CrossRef] [PubMed]
Götzinger E Pircher M Geitzenauer W Retinal pigment epithelium segmentation by polarization sensitive optical coherence tomography. Opt Express . 2008; 16: 16410–16422. [CrossRef] [PubMed]
Baumann B Baumann SO Konegger T Polarization sensitive optical coherence tomography of melanin provides tissue inherent contrast based on depolarization. In: Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIV. Vol 7554. San Francisco, California: SPIE; 2010: 75541M. Available at: https://proceedings.spiedigitallibrary.org/proceeding.aspx?doi=10.1117/12.843226. Accessed February 19, 2010.
Baumann B Baumann SO Konegger T Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization. Biomed Opt Express . 2012; 3: 1670. [CrossRef] [PubMed]
Ahlers C Götzinger E Pircher M Imaging of the retinal pigment epithelium in age-related macular degeneration using polarization-sensitive optical coherence tomography. Invest Ophthalmol Vis Sci . 2010; 51: 2149–2157. [CrossRef] [PubMed]
Michels S Pircher M Geitzenauer W Value of polarisation-sensitive optical coherence tomography in diseases affecting the retinal pigment epithelium. Br J Ophthalmol . 2008; 92: 204–209. [CrossRef] [PubMed]
Park B Pierce M Cense B de Boer J. Real-time multi-functional optical coherence tomography. Opt Express . 2003; 11: 782–793. [CrossRef] [PubMed]
Park B Pierce MC Cense B Real-time fiber-based multi-functional spectral-domain optical coherence tomography at 1.3 um. Opt Express . 2005; 13: 3931–3944. [CrossRef] [PubMed]
Lim Y Hong Y-J Duan L Yamanari M Yasuno Y. Passive component based multifunctional Jones matrix swept source optical coherence tomography for Doppler and polarization imaging. Opt Lett . 2012; 37: 1958–1960. [CrossRef] [PubMed]
Ju MJ Hong Y-J Makita S Advanced multi-contrast Jones matrix optical coherence tomography for Doppler and polarization sensitive imaging. Opt Express . 2013; 21: 19412–19436. [CrossRef] [PubMed]
Park BH Pierce MC Cense B de Boer JF. Jones matrix analysis for a polarization-sensitive optical coherence tomography system using fiber-optic components. Opt Lett . 2004; 29: 2512–2514. [CrossRef] [PubMed]
Durairaj C Chastain JE Kompella UB. Intraocular distribution of melanin in human, monkey, rabbit, minipig and dog eyes. Exp Eye Res . 2012; 98: 23–27. [CrossRef] [PubMed]
Miura M Yamanari M Iwasaki T Imaging polarimetry in age-related macular degeneration. Invest Ophthalmol Vis Sci . 2008; 49: 2661–2667. [CrossRef] [PubMed]
Feeney-Burns L Hilderbrand ES Eldridge S. Aging human RPE: morphometric analysis of macular, equatorial, and peripheral cells. Invest Ophthalmol Vis Sci . 1984; 25: 195–200. [PubMed]
Kennedy CJ Rakoczy PE Constable IJ. Lipofuscin of the retinal pigment epithelium: a review. Eye . 1995; 9: 763–771. [CrossRef] [PubMed]
Sarna T Burke JM Korytowski W Loss of melanin from human RPE with aging: possible role of melanin photooxidation. Exp Eye Res . 2003; 76: 89–98. [CrossRef] [PubMed]
Figure 1
 
Left macula images of a 27-year-old man who did not have an ocular disorder investigated with MF-OCT. (a) OCT en face image, (b) Doppler OCA, and cross sections of (c) OCT, (d) Doppler, (e) cumulative phase retardation, and (f) DOPU. Dotted yellow lines in (a) and (b) indicate the location of (cf). Scale bars: 0.5 mm (a, c)
Figure 1
 
Left macula images of a 27-year-old man who did not have an ocular disorder investigated with MF-OCT. (a) OCT en face image, (b) Doppler OCA, and cross sections of (c) OCT, (d) Doppler, (e) cumulative phase retardation, and (f) DOPU. Dotted yellow lines in (a) and (b) indicate the location of (cf). Scale bars: 0.5 mm (a, c)
Figure 2
 
Screen shot of a custom-made MF-OCT data browser. The OCT en face image and Doppler OCA are displayed in the left column, and cross-sectional images of structural OCT, power Doppler, cumulative phase retardation, and DOPU are displayed in the middle and right columns. By pointing to the position of interest in the en face images using a red line cursor, the corresponding cross-sectional MF-OCT images are simultaneously displayed in the middle and right columns. The operator can mark up one of the cross sections, and the same mark simultaneously appears at the same position in the other cross sections.
Figure 2
 
Screen shot of a custom-made MF-OCT data browser. The OCT en face image and Doppler OCA are displayed in the left column, and cross-sectional images of structural OCT, power Doppler, cumulative phase retardation, and DOPU are displayed in the middle and right columns. By pointing to the position of interest in the en face images using a red line cursor, the corresponding cross-sectional MF-OCT images are simultaneously displayed in the middle and right columns. The operator can mark up one of the cross sections, and the same mark simultaneously appears at the same position in the other cross sections.
Figure 3
 
Right macular images of a 68-year-old man with AMD taken 2 days before the first IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 3
 
Right macular images of a 68-year-old man with AMD taken 2 days before the first IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 4
 
Right macular images of the same patient as in Figure 3. MF-OCT was performed 68 days after the third IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase) (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 4
 
Right macular images of the same patient as in Figure 3. MF-OCT was performed 68 days after the third IVR. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase) (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 5
 
Left macular images of a 43-year-old man with neovascular maculopathy. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 5
 
Left macular images of a 43-year-old man with neovascular maculopathy. (a) Color fundus, (b) ICGA (midphase), (c) FA (late phase), (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (g) OCT, (h) power Doppler, and (i) DOPU. Dotted yellow lines in (df) indicate locations of (gi), respectively. Scale bars: 0.5 mm (d, g).
Figure 6
 
Left macular images of an 80-year-old man with PCV. (a) Color fundus photograph, (b) midphase ICGA, (c) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (f, k) cumulative phase retardation, (g, j) OCT, (h) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (fi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 6
 
Left macular images of an 80-year-old man with PCV. (a) Color fundus photograph, (b) midphase ICGA, (c) FAF, (d) OCT en face image, (e) Doppler OCA, and cross sections of (f, k) cumulative phase retardation, (g, j) OCT, (h) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (fi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 7
 
Right macular images of a 58-year-old man with PCV taken before treatment. (a) Color fundus, (b) midphase of ICGA, (c) late phase of FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) OCT, (h, k) power Doppler, and (i, l) DOPU. Yellow and red arrow pairs in (df) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 7
 
Right macular images of a 58-year-old man with PCV taken before treatment. (a) Color fundus, (b) midphase of ICGA, (c) late phase of FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) OCT, (h, k) power Doppler, and (i, l) DOPU. Yellow and red arrow pairs in (df) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 8
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 7. (a, b) Fly-through rendered volumes cross-sectioned at the locations of Figures 7g through 7i and Figures 7j through 7l, respectively. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For DOPU volume, DOPU values less than 0.7 are displayed. (cf) The whole rendered volumes; (c) combined volume of structural OCT, power Doppler, and low DOPU values, (d) combined volume without structural OCT, (e) power Doppler signal, and (f) low DOPU values.
Figure 8
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 7. (a, b) Fly-through rendered volumes cross-sectioned at the locations of Figures 7g through 7i and Figures 7j through 7l, respectively. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For DOPU volume, DOPU values less than 0.7 are displayed. (cf) The whole rendered volumes; (c) combined volume of structural OCT, power Doppler, and low DOPU values, (d) combined volume without structural OCT, (e) power Doppler signal, and (f) low DOPU values.
Figure 9
 
Right macular images from the same PCV subject as in Figures 7 and 8. Images were taken after a treatment with ranibizumab and PDT. (a) Color fundus, (b) midphase ICGA, (c) late-phase FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) structural OCT, (h, k) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 9
 
Right macular images from the same PCV subject as in Figures 7 and 8. Images were taken after a treatment with ranibizumab and PDT. (a) Color fundus, (b) midphase ICGA, (c) late-phase FA, (f) FAF, (d) OCT en face image, (e) Doppler OCA, and cross-sectional images of (g, j) structural OCT, (h, k) power Doppler, and (i, l) DOPU. Dotted yellow and red lines in (d) and (e) indicate locations of (gi) and (jl), respectively. Scale bars: 0.5 mm (d, g).
Figure 10
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 9. Fly-through cross-sectioned volumes around (a) abnormal choroidal vessels, (b) exudation and RPE damage. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For the DOPU volume, DOPU values less than 0.7 are displayed. Volumetric rendering of (c) the entire volume in which structural OCT is displayed with semitransparent gray color, (d) power Doppler and low DOPU values, and (e) low DOPU values.
Figure 10
 
Volumetric rendering of the 3-D MF-OCT dataset of Figure 9. Fly-through cross-sectioned volumes around (a) abnormal choroidal vessels, (b) exudation and RPE damage. Gray, orange, and green colors represent structural OCT intensity, power Doppler, and low DOPU values, respectively. For the DOPU volume, DOPU values less than 0.7 are displayed. Volumetric rendering of (c) the entire volume in which structural OCT is displayed with semitransparent gray color, (d) power Doppler and low DOPU values, and (e) low DOPU values.
Figure 11
 
Comparison of the color fundus image (a1a3), late phase of FA (b1b3), FAF (c1c3), top-view images of DOPU volume (d1d3), and power Doppler and DOPU registered volume (e1e3). From the left-side column, case 2 (a1e1), case 4 before treatment (a2e2), and case 4 after treatment (a3e3).
Figure 11
 
Comparison of the color fundus image (a1a3), late phase of FA (b1b3), FAF (c1c3), top-view images of DOPU volume (d1d3), and power Doppler and DOPU registered volume (e1e3). From the left-side column, case 2 (a1e1), case 4 before treatment (a2e2), and case 4 after treatment (a3e3).
Table 1
 
Summary of Subjects
Table 1
 
Summary of Subjects
Case Eye Sex Age, y Diagnosis
Subject 1 Right Male 68 AMD
Subject 2 Left Male 43 NM
Subject 3 Left Female 67 PCV
Subject 4 Right Male 73 PCV
Left PCV
Subject 5 Left Male 80 PCV
Subject 6 Left Male 58 PCV
Subject 7 Right Male 68 PCV
Subject 8 Left Male 66 PCV
Subject 9 Left Female 69 PCV
Table 2
 
Abnormality-Detection Test With MF-OCT
Table 2
 
Abnormality-Detection Test With MF-OCT
RPE Damage Abnormal Choroidal Vasculature Hard Exudates Fibrosis
Sensitivity 0.92 0.95 0.56 0.50
Specific detection rate 0.73 0.13 0.18 0.33
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