Quantitative Assessment of Asymmetric Choroidal Outflow in Pachychoroid Eyes on Ultra-Widefield Indocyanine Green Angiography

Choroidal Vortex Vein Drainage System in Central Serous Chorioretinopathy Using Ultra-Widefield Optical Coherence Tomography Angiography

Purpose

To evaluate differences in the choroidal vortex vein drainage system (VV) in eyes between patients with central serous chorioretinopathy (CSC) and unaffected individuals using ultra-widefield optical coherence tomography angiography (UWF-OCTA).

Methods

In this cross-sectional observational study, 40 eyes of patients with CSC and 28 eyes of healthy volunteers were included. The analysis involved the use of UWF-OCTA to analyze the proportion of the choroidal vortex vein drainage system (VV%), choroidal thickness, choroidal vascular volume (CVV), and choroidal vascularity index (CVI) of the VV in each drainage quadrant. The location relationship between the leakage points in fluorescein angiography and the VV was also explored.

Results

A within-group analysis of VV% showed a statistically significant difference in the CSC group (P < 0.001) but not in the control group (P = 0.270). Compared to healthy eyes, CSC eyes had a significantly larger CVV and higher CVI in all regions (all P < 0.05). The superotemporal (ST) drainage system had the largest CVV and thickest choroidal layer among the four drainage quadrants (all P < 0.05) in CSC eyes. The leakage rate in the ST quadrant was significantly higher than that in the inferotemporal quadrant (P < 0.001).

Conclusions

CSC eyes have an asymmetric vortex vein drainage system, with relative hyperperfusion in all VV. Further, the preferential drainage route of the submacular choroid may be the ST drainage system in CSC eyes.

Translational Relevance

Targeting the imbalanced drainage system could be a potential therapeutic approach for CSC.

Choroidal Vein Alterations in Pachychoroid Disease With Choroidal Vascular Hyperpermeability: Evaluated by Wide-Field Indocyanine Green Angiography

Purpose

The purpose of this study was to investigate choroidal vein (ChV) morphological features in pachychoroid disease (PCD) with choroidal vascular hyperpermeability (CVH).

Methods

This retrospective study assessed subfoveal choroidal thickness (SFCT) and CVH area numbers and locations of recruited patients with PCD using multimodal images. ChV alteration patterns, including fusiform, bulbosity, sausaging, confluence, and anastomoses, as well as asymmetric ChVs, dominant ChVs, and non-dominant ChVs, were evaluated using wide-field indocyanine green angiograms.

Results

Of 68 PCD eyes from 35 patients (mean age: 46.16 ± 6.28 years, 71.4% men), 2.9% had uncomplicated pachychoroid, 32.4% had pachychoroid pigment epitheliopathy (PPE), 55.9% central serous chorioretinopathy (CSC), and 8.8% pachychoroid neovasculopathy (PNV). Mean SFCT was 468.65 ± 131.40 µm. Among 419 CVH areas, ChV fusiform, ChV bulbosity, and ChV sausaging accounted for 35.8%, 35.1%, and 29.1%, respectively; 21.2% had ChV confluence and 11.9% had ChV anastomoses. At CVH areas, 13.1% had retinal pigment epithelium (RPE) leakage. ChV fusiform is steadily declining (37.4%, 36.8%, and 22.9%, respectively), and ChV sausaging, ChV anastomoses, and ChV confluence are increased gradually in the PPE, CSC, and PNV groups (21.4%, 30.0%, and 37.1%; 11.4%, 11.1%, and 20.0%; and 19.8%, 20.9%, and 28.6%, respectively). Dominant ChVs had higher CVH area numbers than non-dominant ChVs in the PPE and CSC groups (P = 0.010, P = 0.001).

Conclusions

Different patterns of ChV alterations, including the newly identified ChV confluence, are commonly present at CVH areas in PCD. The CVH areas in PCD eyes are primarily located within the dominant ChVs. These findings provide crucial evidence for advancing our understanding of the underlying mechanisms of PCD pathogenesis.

Scleral Thickness as a Risk Factor for Central Serous Chorioretinopathy and Pachychoroid Neovasculopathy

In the pathophysiology of central serous chorioretinopathy (CSC), scleral changes inducing increased venous outflow resistance are hypothesized to be involved. This work aims to investigate anterior scleral thickness (AST) as a risk factor for pachychoroid disorders. A randomized prospective case-control study was performed at the Ludwig Maximilians University, Department of Ophthalmology. In patients with CSC or pachychoroid neovasculopathy (PNV) and in an age- and refraction-matched control group, swept source optical coherence tomography (SS-OCT) was used to measure anterior scleral thickness (AST). Subfoveal choroidal thickness (SFCT) was assessed using enhanced depth imaging OCT (EDI-OCT). In total, 46 eyes of 46 patients were included in this study, with 23 eyes in the CSC/PNV and 23 eyes in the control group. A significantly higher AST was found in the CSC/PNV compared with the control group (403.5 ± 68.6 (278 to 619) vs. 362.5 ± 62.6 (218 to 498) µm; p = 0.028). Moreover, the CSC/PNV group showed a higher SFCT (392.8 ± 92.8 (191-523) vs. 330.95 ± 116.5 (167-609) µm, p = 0.004). Compared with the age- and refraction-matched controls, patients with CSC and PNV showed a significantly thicker anterior sclera. Scleral thickness might contribute to the venous overload hypothesized to induce pachychoroid phenotypes.

Vortex vein engorgement and different shapes of venous drainage systems in polypoid choroidal vasculopathy vs. age‑related macular degeneration on indocyanine green angiography

There are differences in vortex vein engorgement and appearance in polypoid choroidal vasculopathy (PCV), age-related macular degeneration (AMD), and healthy eyes. The present study aimed to use indocyanine green angiography (ICGA) to find a simple, clinically meaningful method for evaluating the filling degree of vortex veins in various eye diseases. Participant clinical characteristics were recorded. The number of vortex veins (NVV), central vortex vein diameter (CVVD), mean root area of the vortex vein (MRAVV), mean diameter of the thickest peripheral branch (MDPTB), subfoveal choroidal thickness and percentage of vortex vein anastomosis (PVVA) were obtained by marking the vortex veins on ICGA. The proportion of subretinal haemorrhage and the numbers and types of vortex veins in each quadrant were counted separately. The CVVD and MDPTB were significantly increased in the PCV compared with those in the AMD group (P<0.05). The CVVD, MRAV, and PVVA were significantly increased in the PCV compared with those in the healthy group (P<0.05). The type IV vortex vein (complete with ampulla) proportion was the lowest while the type I (vortex vein absent) proportion was the highest in the PCV group (P<0.001). NVV in the inferior-temporal region was increased in the PCV compared with that in the AMD group (P=0.034). Subretinal haemorrhage occurred in the inferior temporal choroid in 47.62% of examined eyes in PCV group, and in the superior temporal choroid in 23.81% of the PCV group, with significant differences between the quadrants (P<0.001). Vortex vein engorgement and shape differed significantly between PCV, AMD and healthy eyes. The vortex vein branches in PCV eyes were significantly dilated in the posterior pole; moreover, the peripheral choroid and the lower proportion of type IV vortex veins may be pathognomonic for PCV.

Qualitative and quantitative evaluation of diabetic choroidopathy using ultra-widefield indocyanine green angiography

To investigate angiographic characteristic features of diabetic choroidopathy, as well as choroidal vascular density (CVD) and fractal dimension (CFD) in diabetic eyes and controls using ultra-widefield (UWF) indocyanine green angiography (ICGA). All patients underwent UWF fluorescein angiography and ICGA. Using imageJ software, CVD and CFD was analyzed. SFCT was assessed using spectral-domain optical coherence tomography. The image parameters were compared based on the DR stage and the presence of diabetic macular edema (DME). One-hundred six eyes from 63 patients (59.11 ± 16.31 years; male [%]: 23 [36.5%]) were included in the DM group, and 40 eyes from 22 subjects were included in the control group. The DM group had a mean age of 59.11 ± 16.31 years and a mean HbA1c percentage of 7.72 ± 1.28%. The most common ICGA findings of DC were choroidal hyperpermeability (57.5%), hypofluorescent spots (48.1%). Salt and pepper pattern (19.8%), inverted inflow phenomenon (3.8%), choroidal arterial tortuosity (24.5%), and late choroidal non-perfusion (6.6%) were more common in advanced DR. The CVD, CFD, and SFCT increased as the DR severity progressed. The DME group had a significantly higher CFD and SFCT than the non-DME group (P < 0.001 and P = 0.019, respectively). The qualitative and quantitative UWF ICGA image analysis revealed that choroidal blood vessels became dilated, complex, and hyperpermeable as the DR progressed. These features of diabetic choroidopathy (DC) were more severe in eyes with DME than the non-DME eyes.

Choroidal arteriovenous anastomoses: a hypothesis for the pathogenesis of central serous chorioretinopathy and other pachychoroid disease spectrum abnormalities

The pachychoroid disease spectrum (PDS) includes several chorioretinal diseases that share specific choroidal abnormalities. Although their pathophysiological basis is poorly understood, diseases that are part of the PDS have been hypothesized to be the result of venous congestion. Within the PDS, central serous chorioretinopathy is the most common condition associated with vision loss, due to an accumulation of subretinal fluid in the macula. Central serous chorioretinopathy is characterized by distinct risk factors, most notably a high prevalence in males and exposure to corticosteroids. Interestingly, sex differences and corticosteroids are also strongly associated with specific types of arteriovenous anastomoses in the human body, including dural arteriovenous fistula and surgically created arteriovenous shunts. In this manuscript, we assess the potential of such arteriovenous anastomoses in the choroid as a causal mechanism of the PDS. We propose how this may provide a novel unifying concept on the pathophysiological basis of the PDS, and present cases in which this mechanism may play a role.

Choroidal morphologic features in central serous chorioretinopathy using ultra-widefield optical coherence tomography

PURPOSE

To analyze the choroidal morphological changes in central serous chorioretinopathy (CSC) using ultra-widefield (UWF)-optical coherence tomography (OCT).

METHODS

This single-center, case-control study included 65 CSC eyes (52 males; age, 55.6 ± 13.0 years) and 65 healthy eyes (50 males; age, 57.1 ± 17.9 years). UWF-OCT (viewing angle, 200°) with real-shape correction was used to create an automated choroidal thickness (CT) map. The CT map had three sub-areas: the central (0-30°), middle (30-60°), and peripheral areas (60-100°), and was divided by vertical and horizontal lines. Differences in the CT and the CT change rate (CTCR) from the central to peripheral areas were examined between the CSC and control groups after adjusting for subjects' demographic and clinical factors. Furthermore, we assessed the vortex veins dilation patterns (VVDP) in the macula and examined the CT and the CTCR differences between CSC patients and controls for each VVDP.

RESULTS

CSC patients had greater CT than those of the controls in all sectors (CSC vs. controls, the peripheral area: supratemporal 284.4 ± 71.2 μm vs. 220.4 ± 71.2 μm, infratemporal 263.3 ± 69.2 μm vs. 195.3 ± 52.3 μm, supranasal 251.9 ± 70.3 μm vs. 189.5 ± 58.1 μm, infranasal 193.6 ± 71.2 μm vs. 146.3 ± 48.9 μm, P < 0.0001 for all sectors). The CTCR was apparently larger in CSC eyes than controls only for the upper-dominant type of VVDP (CSC patients vs. controls, supratemporal 32.1 ± 9.9% vs. 4.6 ± 23.1%, infratemporal 44.0 ± 11.2% vs. 25.6 ± 16.8%, supranasal 42.6 ± 9.8% vs. 22.2 ± 19.4%, infranasal 57.6 ± 41.2% vs. 41.2 ± 13.9%, P < 0.0001 for all sectors).

CONCLUSIONS

CSC has a thicker choroid, even in the peripheral areas, and the macular choroidal thickening was more severe in the upper-dominant type of VVDP. VVDP may affect the location of excessive fluid.

CLINICAL VARIANTS OF PRESUMED ACUTE FOVEALITIS

PURPOSE

To describe four eyes of three patients with presumed acute fovealitis to expand the clinical variants of this recently described disorder.

METHOD

The patients underwent a comprehensive ophthalmic examination, including multimodal imaging and electrophysiological tests.

RESULTS

Three female patients aged from 18 to 24 years presented sudden central visual disturbances in one or both eyes. The visual acuity ranged from 20/25 to 20/70 in the affected eyes. All of them showed a subtle yellowish lesion in the foveola. Fundus autofluorescence and fluorescein angiography were unremarkable. Optical coherence tomography disclosed focal disarrangement of the outer retinal layers restricted to the fovea and hyperreflective lesions above the external limiting membrane. Multifocal electroretinography responses were attenuated. The electrooculogram response was normal. All patients recovered normal visual acuity and the outer retinal layers.

CONCLUSION

Attenuated multifocal electroretinography foveal response and normal electrooculogram are newly described clinical findings in patients with acute fovealitis.

Wide-field OCT-angiography assessment of choroidal thickness and choriocapillaris in eyes with central serous chorioretinopathy

Purpose: To assess wide-field changes in choroidal thickness and choriocapillaris in eyes with central serous chorioretinopathy (CSC) compared with the fellow eyes and eyes from healthy individuals using wide-field swept-source (SS) OCT-Angiography (OCTA).

Methods: A cross-sectional study in which 68 eyes from 34 individual patients affected by unilateral CSC and 32 eyes of 32 age- and sex-matched healthy subjects were evaluated. All subjects underwent wide-field SS-OCTA examination to quantify choroidal thickness and vascular density of the choriocapillaris. To assess the wide-field changes, we developed five 4-by-4 mm square regions located in the posterior pole and in the four quadrants of the peripheral retina (superotemporal, inferotemporal, superonasal, and inferonasal subfields, respectively).

Results: The choroidal thickness of eyes with CSC was greater than that of the fellow eyes in the central and inferonasal subfields (p < 0.001 for the central subfield and p = 0.006 for the inferonasal subfield, respectively). Compared with the choroidal thickness of healthy eyes, that of patients with CSC were significantly greater in all the subfields (p < 0.05 for the fellow eyes and p < 0.05 for eyes with CSC, respectively). Compared with that of healthy eyes, the vascular density of choriocapillaris in eyes of patients with CSC were significantly greater in the central and superotemporal subfields (p < 0.05 for the fellow eyes and p < 0.05 for eyes with CSC, respectively). In the central region, the vascular density of choriocapillaris of the fellow eyes was greater than eyes with CSC (p = 0.023).

Conclusion: CSC appears to be a bilateral disease with asymmetric manifestations. Local factors of the diseased eyes may play an important role in the development of CSC, during which dynamic and regional changes in the choriocapillaris may have happened. Wide-field swept-source OCTA provided a useful tool to study the pathogenesis of CSC.

En face ultra-widefield optical coherence tomography of the vortex vein system in central serous chorioretinopathy

PURPOSE

To investigate whether noninvasive en face ultrawidefield (UWF) OCT can demonstrate salient features of the choroidal vasculature in eyes with central serous chorioretinopathy (CSC).

DESIGN

Retrospective observational case series.

PARTICIPANTS

Patients diagnosed with CSC who underwent UWF indocyanine green angiography (ICGA) and widefield OCT imaging were included.

METHODS

Widefield OCT imaging was performed with a horizontal 23-mm × vertical 20-mm field of view of 5 visual fixations (1 central and 4 peripheral fixations) to compose structural en face UWF OCT montage images and UWF choroidal thickness maps. Automated image alignment was performed before grading.

MAIN OUTCOME MEASURES

A comparison of choroidal vascular findings seen with UWF ICGA and en face UWF OCT images, including size and distribution of choroidal venous drainage areas and identification of dilated choroidal veins (pachyvessels) crossing the physiologic choroidal watershed zones. The spatial correlation between choroidal vascular hyperpermeability on UWF ICGA images and areas of choroidal thickening on UWF choroidal thickness maps was determined.

RESULTS

Forty-two eyes from 27 patients with CSC with a mean age of 56 ± 12 years (range, 31-77 years) were included. Quantitative measures of vortex vein drainage areas on en face UWF OCT images were significantly and positively correlated with those obtained with UWF ICGA (mean Pearson r = 0.825, P < 0.01). Identification of pachyvessels crossing the choroidal watershed zones showed an excellent correlation between UWF ICGA and en face UWF OCT images (mean Spearman ρ = 0.873, P < 0.01). In all cases, choroidal vascular hyperpermeability was observed on UWF ICGA spatially colocalized with areas of choroidal thickening on the UWF choroidal thickness map. Congestion within the entire drainage area of the dominant vortex systems was observed on UWF choroidal thickness maps.

CONCLUSIONS

In eyes with CSC, noninvasive en face UWF OCT imaging can show distinctive features of choroidal venous insufficiency previously identified with UWF ICGA. Ultrawidefield OCT choroidal thickness maps enable quantitative assessment of choroidal congestion.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Correlation of Diabetic Disease Severity to Degree of Quadrant Asymmetry in En Face OCTA Metrics

Purpose

To determine if diabetic retinopathy (DR) severity affects quadrant asymmetry (QA) of optical coherence tomography angiography (OCTA) metrics differentially.

Methods

Ninety eyes (60 patients) with no diabetes mellitus (DM) (n = 39) or varying levels of DR (n = 51) had OCTA images (3 × 3 mm, Cirrus5000) acquired five times and averaged. The vessel length density (VLD) and perfusion density (PD) of the superficial retinal layer (SRL) and deep retinal layer (DRL) were measured. QA was defined as the maximum minus minimum value among four parafoveal Early Treatment Diabetic Retinopathy quadrants, and compared with DR severity by linear regression including fixed effects for each individual and eye.

Results

The mean patient age was 55.5 years (range, 24–88 years) and 60% were male. Comparing severe nonproliferative DR or proliferative DR versus no DM/DR eyes, QA was significantly higher for SRL VLD, and PD (+0.67 ± 0.16 and +0.014 ± 0.003; P < 0.001) and DRL VLD, and PD (+1.25 ± 0.16 and +0.032 ± 0.003; P < 0.001). When comparing mild or moderate nonproliferative DR versus no DM/DR, the DRL VLD, and PD were significantly higher (+0.51 ± 0.13 and +0.015 ± 0.003; P < 0.001). For every step increase in DR severity, there was a +0.20 QA for SRL VLD, +0.004 SRL PD, +0.33 DRL VLD and +0.009 DRL PD (P < 0.001). Regression analysis comparing intraquadrant effect on DR severity demonstrated that the superior quadrant was most affected for all OCTA metrics.

Conclusions

DR severity affects VLD and PD more asymmetrically across Early Treatment Diabetic Retinopathy quadrants with a linear increase in QA for each worsening level of DR. Individual intraeye metrics such as QA can accurately quantify DR severity without concerns for intereye variabilities that could affect the reproducibility and reliability of OCTA quantification.

Choroidal vascular alterations evaluated by ultra-widefield indocyanine green angiography in central serous chorioretinopathy

PURPOSE

This study aims to evaluate choroidal vascular alterations in patients with central serous chorioretinopathy (CSC) using ultra-widefield (UWF) indocyanine green angiography (ICGA).

METHODS

This was a retrospective case-control study conducted at a single tertiary eye center. In total, 36 eyes in patients with either unilateral (24 patients) or bilateral (six patients) treatment-naïve CSC and 30 eyes in 24 age-matched controls were evaluated. The number of quadrants with vortex vein engorgement on UWF ICGA was evaluated. Dilated choroidal vessels affecting the macula were regarded as extended vortex vein engorgement. Choroidal vascular hyperpermeability (CVH) area on late-phase ICGA was quantified using stereographic projection. The parameters were compared with clinical and optical coherence tomographic findings.

RESULTS

Eyes with CSC had larger CVH area, thicker choroid, and more quadrants with vortex vein engorgement and extended vortex vein engorgement compared with control eyes (all P < 0.001). In patients with unilateral CSC, affected eyes had larger CVH area, thicker choroid, and more extended vortex vein engorgements compared with unaffected fellow eyes (all P < 0.001), but vortex vein engorgement did not significantly differ. CVH was significantly correlated with extended vortex vein engorgement (P < 0.001) and subfoveal choroidal thickness (P = 0.007).

CONCLUSIONS

The increased number and binocular symmetry of engorged vortex veins suggest an anatomical predisposition for CSC. CVH area and extended vortex vein engorgement were indicators of choroidal outflow congestion. These parameters may serve as diagnostic clues or predictors of disease development in eyes with CSC.

Ultra-Widefield Indocyanine Green Angiography Reveals Patterns of Choroidal Venous Insufficiency Influencing Pachychoroid Disease

Purpose

To compare patterns of choroidal venous drainage in eyes with pachychoroid disease to those of healthy subjects using ultra-widefield indocyanine green angiography (UWF ICGA).

Methods

Patients with pachychoroid disease and healthy controls were recruited at two referral centers. UWF ICGA images were used to evaluate the proportion of the postequatorial fundus drained by major vortex vein systems in each quadrant and to study the incidence and topography of choroidal vascular hyperpermeability (CVH) and intervortex venous anastomoses. Widefield swept-source optical coherence tomography (SS-OCT) was used to evaluate choroidal thickness at the posterior pole in eyes with pachychoroid disease.

Results

Fifty-two pachychoroid eyes and 26 healthy eyes were evaluated. Eyes with pachychoroid disease showed a significant within-subject variance in the proportion of the postequatorial fundus drained by each vortex vein system (range, 4.1%–48.1%; P < 0.0001) that was not seen in controls (range, 17.3%–31.7%; P = 0.11). CVH was present in all pachychoroid disease eyes and three of 26 controls. Intervortex venous anastomoses were present in 46 of 52 pachychoroid disease eyes and nine of 26 control eyes. Vortex vein systems with large drainage areas showed greater density of CVH spots. SS-OCT demonstrated asymmetric choroidal drainage in the macula of 59% of pachychoroid eyes. CVH and intervortex venous anastomoses were more prominent in areas showing maximal choroidal thickness.

Conclusions

In eyes with pachychoroid disease, imbalanced choroidal venous drainage with congestion of specific vortex vein systems may contribute to a state of choroidal venous insufficiency characterized by regional choroidal thickening, CVH and remodeling of venous drainage routes.

Vortex Vein Imaging: What Can It Tell Us?

This review article summarizes the patho-anatomy of the vortex veins, the major drainage channels for the choroid, and describes the various pathways of diseases associated with vortex vein abnormalities. This report also details the technical advancements to image the vortex veins, such as ultra-widefield indocyanine green angiography, which are critical to elucidate the importance of the vortices in various retino-choroidal disorders. Future applications of these advanced imaging systems to better understand the role of the vortex veins in health and disease are also discussed.

Pachychoroid Spectrum Disease: Underlying Pathology, Classification, and Phenotypes

PURPOSE

Pachychoroid spectrum disease encompasses a set of macular disorders secondary to an abnormally thick choroid. However, the pathological process underlying pachychoroid spectrum disease and its overlap with age-related macular degeneration (AMD) remain unclear. This review aimed to understand the underlying pathology, classification, and phenotypes of pachychoroid spectrum disease.

METHODS

This comprehensive literature review was performed based on a search of peer-reviewed published papers relevant to the current knowledge of pachychoroid disease spectrum.

RESULTS

Pachychoroid is primarily a bilateral phenomenon; the main pathological lesions include choriocapillaris attenuation and abnormally dilated pachyvessels. Chronic central serous chorioretinopathy (CSC) and pachychoroid neovasculopathy (PNV) show similar morphological changes and angiogenic cytokine levels. The subretinal fluid in PNV may not accurately indicate PNV activity. Besides, types 1 and 2 of choroidal neovascularization (CNV) may be involved in primary pachychoroidal disease. Both choroidal arteriosclerosis and higher hydrostatic pressure contribute to hyalinized choroidal arteries and aneurysmal dilatations, resulting in PNV progression to polypoidal choroidal vasculopathy (PCV). Thus, pachychoroid-related type 2 CNV and chronic CSC could be considered as PNV (IIIc) and as a precursor of PNV (IIIa), respectively. Tangled PCV on optical coherence tomography angiography that fails to develop aneurysms should be classified as a subtype of PNV or a forme fruste of PCV.

CONCLUSIONS

Multiple disorders of the pachychoroid spectrum are considered as a continuous disease process, ultimately stimulated by choroidal malfunction. PCV overlaps both AMD and pachychoroid disease, especially for thin-choroid and bilateral types. The terminology and classification of pachychoroid spectrum disease should be used cautiously.

Framework for quantitative three-dimensional choroidal vasculature analysis using optical coherence tomography

Choroidal vasculature plays an important role in the pathogenesis of retinal diseases, such as myopic maculopathy, age-related macular degeneration, diabetic retinopathy, central serous chorioretinopathy, and ocular inflammatory diseases. Current optical coherence tomography (OCT) technology provides three-dimensional visualization of the choroidal angioarchitecture; however, quantitative measures remain challenging. Here, we propose and validate a framework to segment and quantify the choroidal vasculature from a prototype swept-source OCT (PLEX Elite 9000, Carl Zeiss Meditec, USA) using a 3×3 mm scan protocol centered on the macula. Enface images referenced from the retinal pigment epithelium were reconstructed from the volumetric data. The boundaries of the choroidal volume were automatically identified by tracking the choroidal vessel feature structure over the depth, and a selective sliding window was applied for segmenting the vessels adaptively from attenuation-corrected enface images. We achieved a segmentation accuracy of 96% ± 1% as compared with manual annotation, and a dice coefficient of 0.83 ± 0.04 for repeatability. Using this framework on both control (0.00 D to -2.00 D) and highly myopic (-8.00 D to -11.00 D) eyes, we report a decrease in choroidal vessel volume (p<0.001) in eyes with high myopia.

Multimodal Imaging in Pachychoroid Spectrum

Diagnostic investigation on pachychoroid spectrum disease (PSD) has been growing along with the rapid advancement of imaging technology. In optical coherence tomography (OCT)-based studies, choroidal thickness profile, luminal and stromal choroidal ratio, and abnormalities in the neurosensory retina have demonstrated various patterns in different clinical entities related to PSD. The emerging role of OCT angiography (OCTA) has been expanded to involve the quantitative analysis of the OCTA parameters in different clinical entities of PSD and to evaluate the choriocapillaris signal void and vessel density as indicators of choriocapillaris ischemia. OCTA has broadened our knowledge in characterization and assessment of both active and quiescent choroidal neovascularization and its association with treatment response. Recent studies using indocyanine green angiography (ICG) have focused on the evaluation of choroidal vascular hyperpermeability and its relationship with other pachychoroid related features. Ultrawidefield ICG enables observation and characterization of peripheral choroidal pathologies and their associations with macular abnormalities. Multicolor imaging is an emerging modality with the capability to demonstrate early abnormalities in PSD. We summarize all investigations reflecting the new insights into the application of multimodal imaging for PSD and focuses on novel findings observed in different clinical entities with each imaging modality.

Quantitative analysis of choroidal vasculature in polypoidal choroidal vasculopathy using ultra-widefield indocyanine green angiography

Polypoidal choroidal vasculopathy (PCV) is a common choroidal vascular disease particularly in Asians. However, the underlying pathogenesis of PCV is still yet to be fully elucidated, and the correlation between choroidal vasculature and treatment response of PCV are poorly understood. Accordingly, we sought to find clues to understand the pathogenesis and prognosis of PCV by quantitatively evaluating choroidal vasculature from the entire fundus using ultra-widefield (UWF) indocyanine green angiography (ICGA). In this study, 32 eyes from 29 patients with treatment naïve PCV and 30 eyes from 30 healthy control participants were enrolled. Choroidal vascular density (CVD) of PCV eyes was higher than normal eyes in majority regions including the periphery. CVD was positively correlated with choroidal thickness and choroidal hyperpermeability, supporting that the pathogenesis of PCV may include choroidal congestion and dilatation. Thicker choroid and higher CVD were also correlated with poor treatment response after anti-VEGF injections. The CVD, quantified from UWF ICGA can also be used as an effective image biomarker to predict the treatment response in PCV.