Choroidal vascular changes in age-related macular degeneration

Quantifying ocular microcirculation in hypertension patients with carotid artery stenosis

Background

Carotid artery stenosis (CAS) is one of the most common macrovascular complications of hypertension. The ophthalmic artery springs from the internal carotid artery; however, the effect of CAS on ocular microcirculation has not been quantified in hypertension patients. This study aimed to quantify ocular microcirculation metrics in hypertension with CAS (HCAS) patients and to explore the relationship between micro- and macroangiopathy in hypertension.

Methods

All participants (community-based) underwent detailed assessments, including carotid ultrasonography, optical coherence tomography angiography (OCTA), and enhanced depth imaging (EDI)-OCT. CAS was diagnosed using carotid ultrasonography. Retinal microcirculation metrics, including vessel density (VD), skeleton density (SD), fractal dimension (FD), and foveal avascular zone (FAZ), were quantified using OCTA and ImageJ software. Choroidal microcirculation metrics, including subfoveal choroidal thickness (SFCT), luminal area (LA), and choroidal vascularity index (CVI), were quantified using EDI-OCT and ImageJ. Retinal vessel caliber metrics, including central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and artery/vein ratio (AVR), were calculated using revised formulas. The above metrics were compared among the HCAS group, hypertension with no CAS (HNCAS) group, and healthy control group. The mutual effects between ocular metrics and CAS were evaluated using regression analyses.

Results

In a comparison of the HCAS vs. HNCAS groups, retinal metrics including VD, SD, FD, and choroidal metrics including CVI and LA were significantly decreased in the HCAS group (all p < 0.05); however, FAZ, SFCT, and retinal vessel caliber metrics including CRAE, CRVE, and AVR were comparable between groups (all p > 0.05). In a comparison of HNCAS and the healthy control group, VD, SD, and CRAE showed that AVR was significantly decreased in the HNCAS group (all p < 0.05); meanwhile, choroidal metrics were comparable between groups (all p > 0.05). Linear regression analyses showed that intima-media thickness (IMT) (p = 0.01) and peak systolic velocity (PSV) (p = 0.002) were negatively related to retinal VD in hypertension patients. Logistic regression analyses disclosed that older age (p < 0.001), smoking history (p = 0.002), lower VD (p = 0.04), SD (p = 0.02), and CVI (p < 0.001) were related to the presence of CAS in hypertension patients.

Conclusion

CAS in hypertension-induced hypoperfusion in retinal and choroidal microcirculation and the decreased retinal VD and choroidal CVI were significantly associated with the presence of CAS in patients with hypertension, suggesting that hypertension macro- and microangiopathy were mutually affected and share the common pathophysiology. Furthermore, OCT could be a useful tool to assess hypertension patient's CAS risk profiles in a non-invasive way.

Optical coherence tomography choroidal enhancement using generative deep learning

Spectral-domain optical coherence tomography (SDOCT) is the gold standard of imaging the eye in clinics. Penetration depth with such devices is, however, limited and visualization of the choroid, which is essential for diagnosing chorioretinal disease, remains limited. Whereas swept-source OCT (SSOCT) devices allow for visualization of the choroid these instruments are expensive and availability in praxis is limited. We present an artificial intelligence (AI)-based solution to enhance the visualization of the choroid in OCT scans and allow for quantitative measurements of choroidal metrics using generative deep learning (DL). Synthetically enhanced SDOCT B-scans with improved choroidal visibility were generated, leveraging matching images to learn deep anatomical features during the training. Using a single-center tertiary eye care institution cohort comprising a total of 362 SDOCT-SSOCT paired subjects, we trained our model with 150,784 images from 410 healthy, 192 glaucoma, and 133 diabetic retinopathy eyes. An independent external test dataset of 37,376 images from 146 eyes was deployed to assess the authenticity and quality of the synthetically enhanced SDOCT images. Experts' ability to differentiate real versus synthetic images was poor (47.5% accuracy). Measurements of choroidal thickness, area, volume, and vascularity index, from the reference SSOCT and synthetically enhanced SDOCT, showed high Pearson's correlations of 0.97 [95% CI: 0.96-0.98], 0.97 [0.95-0.98], 0.95 [0.92-0.98], and 0.87 [0.83-0.91], with intra-class correlation values of 0.99 [0.98-0.99], 0.98 [0.98-0.99], and 0.95 [0.96-0.98], 0.93 [0.91-0.95], respectively. Thus, our DL generative model successfully generated realistic enhanced SDOCT data that is indistinguishable from SSOCT images providing improved visualization of the choroid. This technology enabled accurate measurements of choroidal metrics previously limited by the imaging depth constraints of SDOCT. The findings open new possibilities for utilizing affordable SDOCT devices in studying the choroid in both healthy and pathological conditions.

Retinal neurodegeneration in age-related macular degeneration

Age-related macular degeneration (AMD) is a complex and multifactorial disease characterized by the damage of the unit comprised of the photoreceptors, retinal pigment epithelium (RPE), Bruch's membrane, and choriocapillaris. Although the outer retina appears to be mainly affected in this disorder, several evidences exhibit that also the inner retina may be impaired. In this review we will provide a description of the prominent histologic and imaging findings suggesting an inner retinal loss in these eyes. In details, structural optical coherence tomography (OCT) technology proved either the inner and outer retina is impacted by AMD and that these two impairments are associated. Therefore, the purpose of this review is to provide a description of the role of neurodegeneration in AMD in order to better understand the relationship between neuronal loss and the outer retinal damage in this disease.

Vascular changes of the choroid and their correlations with visual acuity in diabetic retinopathy

Objective

To investigate changes in the choroidal vasculature and their correlations with visual acuity in diabetic retinopathy (DR).

Methods

The cohort was composed of 225 eyes from 225 subjects, including 60 eyes from 60 subjects with healthy control, 55 eyes from 55 subjects without DR, 46 eyes from 46 subjects with nonproliferative diabetic retinopathy (NPDR), 21 eyes from 21 subjects with proliferative diabetic retinopathy (PDR), and 43 eyes from 43 subjects with clinically significant macular edema (CSME). Swept-source optical coherence tomography (SS-OCT) was used to image the eyes with a 12-mm radial line scan protocol. The parameters for 6-mm diameters of region centered on the macular fovea were analyzed. Initially, a custom deep learning algorithm based on a modified residual U-Net architecture was utilized for choroidal boundary segmentation. Subsequently, the SS-OCT image was binarized and the Niblack-based automatic local threshold algorithm was employed to calibrate subfoveal choroidal thickness (SFCT), luminal area (LA), and stromal area (SA) by determining the distance between the two boundaries. Finally, the ratio of LA and total choroidal area (SA + LA) was defined as the choroidal vascularity index (CVI). The choroidal parameters in five groups were compared, and correlations of the choroidal parameters with age, gender, duration of diabetes mellitus (DM), glycated hemoglobin (HbA1c), fasting blood sugar, SFCT and best-corrected visual acuity (BCVA) were analyzed.

Results

The CVI, SFCT, LA, and SA values of patients with DR were found to be significantly lower compared to both healthy patients and patients without DR (P < 0.05). The SFCT was significantly higher in NPDR group compared to the No DR group (P < 0.001). Additionally, the SFCT was lower in the PDR group compared to the NPDR group (P = 0.014). Furthermore, there was a gradual decrease in CVI with progression of diabetic retinopathy, reaching its lowest value in the PDR group. However, the CVI of the CSME group exhibited a marginally closer proximity to that of the NPDR group. The multivariate regression analysis revealed a positive correlation between CVI and the duration of DM as well as LA (P < 0.05). The results of both univariate and multivariate regression analyses demonstrated a significant positive correlation between CVI and BCVA (P = 0.003).

Conclusion

Choroidal vascular alterations, especially decreased CVI, occurred in patients with DR. The CVI decreased with duration of DM and was correlated with visual impairment, indicating that the CVI might be a reliable imaging biomarker to monitor the progression of DR.

Macular and peripapillary Choroidal Vascularity Index in children with different refractive status

OBJECTIVES

To characterize choroidal vascular changes in children with different refractive status.

METHODS

A study including 5864 children aged 6-9 years was performed to investigate the choroidal vascular index (CVI) in myopic, emmetropic and hyperopic eyes. Each participant had a comprehensive ocular examination with cycloplegic autorefraction performed, axial length (AL) measured and Swept Source-Optical Coherence Tomography (SS-OCT) scans acquired. Choroidal thickness (ChT) was measured by built-in software, and CVI was calculated using a previously validated self-developed algorithm.

RESULTS

The mean ChT and CVI were 275.88 ± 53.34 μm and 34.91 ± 3.83 in the macula region, and 191.96 ± 46.28 μm and 32.35 ± 4.21 in the peripapillary region. CVI was significantly lowest for myopes, followed by emmetropes and hyperopes (P < 0.001). CVI varied between different sectors separated by the Early Treatment of Diabetic Retinopathy Study (ETDRS) grid (P < 0.001). Macular CVI decreased horizontally from nasal to temporal quadrant with lowest in center fovea, and vertically from superior to inferior quadrants. Peripapillary CVI was highest in the nasal and lowest in the inferior sector. Multiple regression showed that spherical equivalent (SE), AL, intraocular pressure (IOP), ChT, age, and gender were significantly related to CVI (P < 0.05).

CONCLUSIONS

In children, the distribution of CVI in the posterior pole is not uniform. A decreased CVI was observed from hyperopia to myopia and was associated with decreased SE, elongated AL, and choroidal thinning. Further study of changes in CVI during myopia onset and progression is required to better understand the role of the choroidal vasculature in myopia development.

Insights into the pattern of choroidal vascularity index changes in idiopathic macular hole

This retrospective study aimed to investigate the changes in choroidal vascularity index (CVI) before and after surgery for idiopathic macular hole (MH). Enhanced depth imaging optical coherence tomography (EDI-OCT) images were analyzed at baseline and at 1-week, 1-month, and 3-month postoperative visits. A total of 97 patients (97 eyes) were included in the study. At baseline, overall CVI and macular CVI showed negative correlation with axial length (AL) and positive correlation with central corneal thickness (CCT). There were no significant differences in macular CVI or overall CVI between affected and healthy eyes, as well as in subgroup analysis of different stages of macular CVI. Following surgery, there was a significant decrease in CVI at 1 week postoperatively, followed by a gradual recovery to baseline levels over time. The observed changes in CVI may be attributed to factors such as air tamponade, pressure changes, and photoreceptor metabolism. This study provides insights into the pattern of CVI changes associated with MH surgery. The findings suggest that stage 4 MH is associated with decreased macular CVI in affected eyes. These results contribute to a better understanding of the effects of surgery on choroidal blood flow in MH patients.

Visualization of choroidal vasculature in pigmented mouse eyes from experimental models of AMD

A variety of techniques exist to investigate retinal and choroidal vascular changes in experimental mouse models of human ocular diseases. While all have specific advantages, a method for evaluating the choroidal vasculature in pigmented mouse eyes has been more challenging especially for whole mount visualization and morphometric analysis. Here we report a simple, reliable technique involving bleaching pigment prior to immunostaining the vasculature in whole mounts of pigmented mouse choroids. Eyes from healthy adult pigmented C57BL/6J mice were used to establish the methodology. The retina and anterior segment were separated from the choroid. The choroid with retinal pigment epithelial cells (RPE) and sclera was soaked in 1% ethylenediaminetetraacetic acid (EDTA) to remove the RPE. Tissues were fixed in 2% paraformaldehyde (PFA) in phosphate-buffered saline (PBS). Choroids were subjected to melanin bleaching with 10% hydrogen peroxide (H2O2) at 55 °C for 90 min, washed in PBS and then immunostained with anti-podocalyxin antibody to label vascular endothelium followed by Cy3-AffiniPure donkey anti-goat IgG at 4 °C overnight. Images of immunostained bleached choroids were captured using a Zeiss 710 confocal microscope. In addition to control eyes, this method was used to analyze the choroids from subretinal sodium iodate (NaIO3) RPE atrophy and laser-induced choroidal neovascularization (CNV) mouse models. The H2O2 pretreatment effectively bleached the melanin, resulting in a transparent choroid. Immunolabeling with podocalyxin antibody following bleaching provided excellent visualization of choroidal vasculature in the flat perspective. In control choroids, the choriocapillaris (CC) displayed different anatomical patterns in peripapillary (PP), mid peripheral (MP) and far peripheral (FP) choroid. Morphometric analysis of the vascular area (VA) revealed that the CC was most dense in the PP region (87.4 ± 4.3% VA) and least dense in FP (79.9 ± 6.7% VA). CC diameters also varied depending on location from 11.4 ± 1.97 mm in PP to 15.1 ± 3.15 mm in FP. In the NaIO3-injected eyes, CC density was significantly reduced in the RPE atrophic regions (50.7 ± 5.8% VA in PP and 45.8 ± 6.17% VA in MP) compared to the far peripheral non-atrophic regions (82.8 ± 3.8% VA). CC diameters were significantly reduced in atrophic regions (6.35 ± 1.02 mm in PP and 6.5 ± 1.2 mm in MP) compared to non-atrophic regions (14.16 ± 2.12 mm). In the laser-induced CNV model, CNV area was 0.26 ± 0.09 mm2 and luminal diameters of CNV vessels were 4.7 ± 0.9 mm. Immunostaining on bleached choroids with anti-podocalyxin antibody provides a simple and reliable tool for visualizing normal and pathologic choroidal vasculature in pigmented mouse eyes for quantitative morphometric analysis. This method will be beneficial for examining and evaluating the effects of various treatment modalities on the choroidal vasculature in mouse models of ocular diseases such as age-related macular degeneration, and degenerative genetic diseases.

Evaluation of peripapillary choroidal vascularity index in young smokers

Purpose: This retrospective study aimed to compare the peripapillary choroidal vascularity index (CVI) between young smokers who smoked less than 5 packs/year and non-smokers.Methods: The study included 52 smokers and 67 non-smokers, and comprehensive eye examinations were performed on all participants. Axial lengths (AL) were measured, and peripapillary enhanced depth imaging optical coherence tomography (EDI-OCT) images were obtained and evaluated using the Open Source ImageJ software. The CVI, total choroidal area (TCA), luminal area (LA), stromal area (SA), and retinal nerve fibre layer (RNFL) quadrants were compared between the two groups.Results: The mean age of the smokers was 23.76 ± 1.84 years, and for non-smokers, it was 23.98 ± 2.18 years. The mean peripapillary CVI for smokers was 0.65 ± 0.08, and for non-smokers, it was 0.67 ± 0.03. No statistically significant difference in CVI was observed between the two groups. However, statistically significant differences were found in the temporal inferior (TI), temporal superior (TS), nasal inferior (NI), and nasal superior (NS) quadrants of the RNFL between the two groups (p < 0.05). There was no correlation between the number of packs/year and CVI values in the smoking group (r = 0.031, p = 0.826).Conclusion: The study revealed no significant difference in CVI among young smokers who smoked less than 5 packs/year compared to non-smokers. However, there was a statistically significant decrease in the TI, TS, NI, and NS quadrants of the RNFL in early-age smokers.

The Choroidal Vascularity Index Versus Optical Coherence Tomography Angiography in the Evaluation of the Choroid with a Focus on Age-Related Macular Degeneration

The choroid is the most vascularized structure of the eye and it is fundamental for the trophism of the outer retina. Its proper functioning and homeostasis represent key points in maintaining normal retinal physiology. Choroidal alterations may be implicated in the development and progression of numerous pathologies; therefore, in-depth studies using imaging techniques can be of crucial relevance to understanding the pathophysiology of retinal-choroidal diseases. The advent of spectral-domain optical coherence tomography (SDOCT) has enabled the non-invasive study of the choroid in vivo and the most recent development, optical coherence tomography angiography (OCTA), allows for the high-resolution visualization of the choriocapillaris and the choroid in regard to vascularization. The choroidal vascularity index (CVI) is a new parameter calculated on SDOCT scans and is defined as the ratio of the luminal area to the total choroidal area. In this review, a study of the choroid using OCTA and CVI will be evaluated in depth and the pros and cons of these two methods will be analyzed, with a particular focus on age-related macular degeneration.

Longitudinal Assessment of the Choroidal Vascularity Index in Eyes with Branch Retinal Vein Occlusion-Associated Cystoid Macular Edema

INTRODUCTION

Cystoid macular edema (CME) is the most common cause of central vision loss in eyes with branch retinal vein occlusion (BRVO eyes). In recent literature, choroidal vascularity index (CVI) has been proposed to be an enhanced depth imaging optical coherence tomography (EDI-OCT) metric that may help characterize choroidal vascular changes in the setting of retinal ischemia, and potentially prognose visual outcomes and treatment patterns for patients with BRVO-related CME. This study sought to further characterize choroidal vascular changes in BRVO by comparing the CVI, subfoveal choroidal thickness (SFCT), and central subfield thickness (CST) in BRVO eyes with CME compared to unaffected fellow eyes.

METHODS

This was a retrospective cohort study. Subjects included treatment-naïve BRVO eyes with CME diagnosed within 3 months of onset of symptoms and unaffected fellow eyes. EDI-OCT images were collected at baseline and at the 12-month follow-up visit. CVI, SFCT, and CST were measured. Demographics, treatment patterns, and best-corrected visual acuity (VA) were abstracted. Median CVI, SFCT, CST, and VA were compared between the two cohorts. Longitudinal relationships between these variables were analyzed.

RESULTS

A total of 52 treatment-naïve eyes with BRVO and CME and 48 unaffected fellow eyes were identified. Baseline CVI was lower in eyes with BRVO than in fellow eyes (64.7% vs. 66.4%, P = 0.003). At 12 months, there was no difference in CVI between BRVO eyes and fellow eyes (65.7% vs 65.8%, P = 0.536). In BRVO eyes, there was a strong correlation between reduced CST and improved VA over the 12-month study period (r = 0.671, P < 0.001).

CONCLUSION

There are differences in CVI in treatment-naïve BRVO eyes with CME at presentation compared to fellow eyes, but these differences resolve over time. Anatomic changes in macular thickness in BRVO eyes with CME may be correlated with VA outcomes.

Choroidal structure investigated by choroidal vascularity index in patients with inherited retinal diseases

PURPOSE

To evaluate the choroidal structure in patients with inherited retinal diseases (IRDs) by investigating the choroidal vascularity index (CVI).

METHODS

The present study was conducted on 113 IRD patients and 113 sex- and age-matched healthy individuals. Patients' data was extracted from the Iranian National Registry for IRDs (IRDReg®). Total choroidal area (TCA) was determined between retinal pigment epithelium and choroid-scleral junction,1500 microns on either side of the fovea. Luminal area (LA) was considered as the black area corresponding to the choroidal vascular spaces, following Niblack binarization. CVI was calculated as the ratio of the LA to the TCA. CVI and other parameters were compared among different types of IRD and the control group.

RESULTS

The IRD diagnosis included retinitis pigmentosa (n = 69), cone-rod dystrophy (n = 15), Usher syndrome (n = 15), Leber congenital amaurosis (n = 9), and Stargardt disease (n = 5). Sixty-one (54.0%) individuals of each of the study and control groups were male. The average CVI was 0.65 ± 0.06 in the IRD patients and 0.70 ± 0.06 in the control group (P < 0.001). Accordingly, the average of TCA and LA were 2.32 ± 0.63 and 1.52 ± 0.44 mm [1] in patients with IRDs, respectively. The measurements for the TCA and the LA were significantly lower in all subtypes of IRD (P-values < 0.05).

CONCLUSION

CVI is significantly lower in patients with IRD than in healthy age-matched individuals. Choroidal changes in IRDs may be related to the changes in the lumen of the choroidal vessels rather than the stromal changes.

A Deep Learning-Based Fully Automated Program for Choroidal Structure Analysis Within the Region of Interest in Myopic Children

Purpose

To develop and validate a fully automated program for choroidal structure analysis within a 1500-µm-wide region of interest centered on the fovea (deep learning-based choroidal structure assessment program [DCAP]).

Methods

A total of 2162 fovea-centered radial swept-source optical coherence tomography (SS-OCT) B-scans from 162 myopic children with cycloplegic spherical equivalent refraction ranging from -1.00 to -5.00 diopters were collected to develop the DCAP. Medical Transformer network and Small Attention U-Net were used to automatically segment the choroid boundaries and the nulla (the deepest point within the fovea). Automatic denoising based on choroidal vessel luminance and binarization were applied to isolate choroidal luminal/stromal areas. To further compare the DCAP with the traditional handcrafted method, the luminal/stromal areas and choroidal vascularity index (CVI) values for 20 OCT images were measured by three graders and the DCAP separately. Intraclass correlation coefficients (ICCs) and limits of agreement were used for agreement analysis.

Results

The mean ± SD pixel-wise distances from the predicted choroidal inner, outer boundary, and nulla to the ground truth were 1.40 ± 1.23, 5.40 ± 2.24, and 1.92 ± 1.13 pixels, respectively. The mean times required for choroidal structure analysis were 1.00, 438.00 ± 75.88, 393.25 ± 78.77, and 410.10 ± 56.03 seconds per image for the DCAP and three graders, respectively. Agreement between the automatic and manual area measurements was excellent (ICCs > 0.900) but poor for the CVI (0.627; 95% confidence interval, 0.279-0.832). Additionally, the DCAP demonstrated better intersession repeatability.

Conclusions

The DCAP is faster than manual methods. Also, it was able to reduce the intra-/intergrader and intersession variations to a small extent.

Translational Relevance

The DCAP could aid in choroidal structure assessment.

Short-term postoperative changes in the choroidal vascularity index in patients with a unilateral epiretinal membrane

BACKGROUND

To investigate short-term choroidal structural and vascular changes after epiretinal membrane (ERM) surgery.

METHODS

In this retrospective study, 65 patients with unilateral ERM underwent pars plana vitrectomy combined with cataract surgery and were examined one day before surgery and one week, one month, and three months after surgery. Choroidal thickness (CT) and choroidal vascular index (CVI) were evaluated using horizontal enhanced depth imaging optical coherence tomography (EDI-OCT) scans and were further calculated using semi-automatic algorithms using MATLAB R2017a.

RESULTS

Preoperatively, CVI was higher in eyes with ERM (61.70 ± 5.17%) than in fellow eyes (59.99 ± 5.26%). CVI increased significantly at one week after surgery (62.14 ± 5.02%) and decreased at 1 and 3 months after surgery (60.76 ± 4.97% and 60.4 ± 4.83%, respectively). The change was pronounced in the nasal region (p < 0.001) and central region (p < 0.05). CT in the temporal macula increased at 1 week (239.65 ± 72.98 μm) after surgery and decreased at 1 and 3 months after surgery (222.15 ± 71.91 μm and 222.33 ± 65.72 μm, respectively; p < 0.01).

CONCLUSIONS

Short-term postoperative variations in the choroid have been demonstrated in eyes with ERM. This may be related to the release of macular traction. CVI assessment using EDI-OCT may be a useful tool for investigating choroidal structural changes accompanying ERM and postoperative period.

Choroidal and Retinal Imaging Biomarkers in Different Types of Macular Neovascularization

BACKGROUND

The aim of this study was to investigate optical coherence tomography (OCT) and OCT angiography (OCTA) parameters in patients with neovascular age-related macular degeneration (nAMD) and macular neovascularization (MNV) type 1, type 2, and type 3.

METHODS

In this retrospective study, 105 treatment-naïve eyes of 105 patients (60 men and 45 women) with a definite diagnosis of active nAMD and MNV of different types and 105 frequency-matched age and gender healthy subjects were evaluated (61 men and 44 women). All subjects underwent a full ophthalmic examination and multimodal imaging assessment, including spectral domain (SD) OCT and OCTA. The main outcome measures were choroidal vascularity index (CVI), subfoveal choroidal thickness (SFCT), central macular thickness (CMT), and outer retina to choriocapillaris (ORCC) MNV flow area (ORCCFA).

RESULTS

Significant differences were found in terms of CVI, CMT, and ORCCFA between MNV 1 and the two other groups. CVI was significantly different between MNV 1 and healthy control patients (p < 0.001) and between MNV 1 and MNV 2 (p < 0.001). ORCCFA and CMT were significantly different between MNV1 and MNV2 (p < 0.005). The difference in subfoveal CT between the three groups was not statistically significant (p = 0.458). A significant negative correlation was found between CVI and ORCCFA. Furthermore, CVI showed a positive correlation with subfoveal CT.

Deep learning based diagnostic quality assessment of choroidal OCT features with expert-evaluated explainability

Various vision-threatening eye diseases including age-related macular degeneration (AMD) and central serous chorioretinopathy (CSCR) are caused due to the dysfunctions manifested in the highly vascular choroid layer of the posterior segment of the eye. In the current clinical practice, screening choroidal structural changes is widely based on optical coherence tomography (OCT) images. Accordingly, to assist clinicians, several automated choroidal biomarker detection methods using OCT images are developed. However, the performance of these algorithms is largely constrained by the quality of the OCT scan. Consequently, determining the quality of choroidal features in OCT scans is significant in building standardized quantification tools and hence constitutes our main objective. This study includes a dataset of 1593 good and 2581 bad quality Spectralis OCT images graded by an expert. Noting the efficacy of deep-learning (DL) in medical image analysis, we propose to train three state-of-the-art DL models: ResNet18, EfficientNet-B0 and EfficientNet-B3 to detect the quality of OCT images. The choice of these models was inspired by their ability to preserve the salient features across all the layers without information loss. To evaluate the attention of DL models on the choroid, we introduced color transparency maps (CTMs) based on GradCAM explanations. Further, we proposed two subjective grading scores: overall choroid coverage (OCC) and choroid coverage in the visible region(CCVR) based on CTMs to objectively correlate visual explanations vis-à-vis DL model attentions. We observed that the average accuracy and F-scores for the three DL models are greater than 96%. Further, the OCC and CCVR scores achieved for the three DL models under consideration substantiate that they mostly focus on the choroid layer in making the decision. In particular, of the three DL models, EfficientNet-B3 is in close agreement with the clinician's inference. The proposed DL-based framework demonstrated high detection accuracy as well as attention on the choroid layer, where EfficientNet-B3 reported superior performance. Our work assumes significance in bench-marking the automated choroid biomarker detection tools and facilitating high-throughput screening. Further, the methods proposed in this work can be adopted for evaluating the attention of DL-based approaches developed for other region-specific quality assessment tasks.

Multimodal Imaging of Choroidal Structural in Torpedo Maculopathy

Objective

To report a case of torpedo maculopathy with multimodal fundus imaging methods, and apply the choroid vascularity index to quantitatively describe the choroidal structural changes in torpedo maculopathy.

Case presentation

An asymptomatic 41-year-old Chinese woman with an incidentally found yellowish-white macular lesion in her left eye was referred to our hospital. She was unaware of any prior medical conditions. The best corrected visual acuity (BCVA) was 20/20 OD and 20/25 OS, respectively. Fundus exam of her left eye revealed a well-circumscribed torpedo-like hypopigmented lesion in the macula region, and the tapered edge directed toward the fovea. Pigment deposition could be seen in the inferotemporal portion of the torpedo lesion. Fluorescein angiography showed the corresponding window defect without leakage and fundus autofluorescence demonstrated low signal throughout the lesion. Enhanced depth imaging optical coherence tomography revealed outer retinal attenuation, subretinal cavitation, subtle inner choroidal excavation and thinning of outer nuclear layer. The diagnosis of torpedo maculopathy was clinically made. Choroidal vascularity index (CVI) and sub-foveal choroidal thickness (SFCT) were applied to display changes of choroidal structure. The results implied that both subfoveal CVI and SFCT of the affected eye seemed relatively lower when compared with the fellow eye. Optical coherence tomography angiography showed reduced density of the choriocapillaris in the temporal area of the lesion and increased capillary density in the nasal area. Functional examinations, including microperimetry, multifocal electroretinogram and static perimetry also revealed reduced retinal sensitivity, decreased stimulated amplitude and suspected scotoma in the lesion area. After 12 months of follow-up, the patient's visual acuity and the clinical appearance of the lesion were unchanged.

Conclusion

The torpedo maculopathy may be identified by abnormal appearance with multimodal imaging. Decreased choroidal vascularity in the lesion area measured quantitatively by choroid vascularity index may play a role in pathogenesis of torpedo maculopathy.

Influence of scan direction on subfoveal choroidal vascularity index using optical coherence tomography

We investigated the influence of scan direction on subfoveal choroidal vascularity index (CVI) measurements using spectral-domain optical coherence tomography (SD-OCT) in young healthy subjects. Seventy-eight eyes of 41 healthy volunteers were included. Choroidal structures were obtained using SD-OCT with enhanced depth imaging (EDI) through radial scans at the center of the macula. The subfoveal choroidal images in the horizontal (0°), 45°, vertical (90°) and − 45° directions were recorded and CVIs were analyzed according to their respective directions using image binarization. Additionally, subfoveal choroidal thickness (SFCT), and axial eye length were measured. The SFCT and subfoveal CVI showed a negative correlation but were only significant for the 45° scan (Pearson’s r = − 0.262, P = 0.021). The axial eye length and subfoveal CVI had no significant correlation in any direction (all P > 0.05). In the Bland–Altman plot, the subfoveal CVI measurement showed high agreement among the four scan directions. When the SFCT was ≥ 300 µm, there was no difference in the measured values of the subfoveal CVI among the four scan directions; however, when the SFCT was < 300 µm, there was a significant difference in subfoveal CVI among the scan directions (one-way analysis of variance, F = 4.685, P = 0.004). In subfoveal CVI measurement, it is considered that the horizontal (0°) scan can represent the vertical (90°) or oblique (45°, − 45°) scans. However, when the SFCT is thinner, the subfoveal CVI in each direction of radial scan may vary significantly. Hence, caution is required in the interpretation.

Choroidal Vascularity Index in Central and Branch Retinal Vein Occlusion

(1) Background: we aimed to evaluate choroidal vascularity change in eyes with central and branch retinal vein occlusion (RVO). (2) Methods: in this retrospective cross-sectional study, we reviewed the records of 47 patients with recent-onset, naïve, unilateral retinal vein occlusion. Enhanced-depth imaging optical coherence tomography scans were binarized using the ImageJ software; luminal area (LA) and total choroidal area (TCA) were measured. The choroidal vascularity index (CVI) was calculated as the proportion of LA to TCA. Depending on the pattern of macular oedema, eyes were classified as having no macular oedema (nME), cystoid macular oedema (CME), cystoid macular oedema with serous retinal detachment (mixed). (3) Results: CVI, TCA and LA were greater in eyes with RVO than in fellow, unaffected eyes. No difference was found between central and branch RVO except for central macular thickness (CMT). When compared with controls, eyes with CME presented a significant increase in subfoveal choroidal thickness, CMT, TCA, LA and CVI; eyes with mixed macular oedema had greater CMT and CVI than contralateral eyes; no significant differences in any of the considered parameters were observed in eyes with nME. (4) Conclusions: The results suggest that RVO alters the vascularity of the choroid that varies according to the type of macular oedema.

The status of the choroid in patients with optic disc drusen

PURPOSE

To investigate the subfoveal and peripapillary choroidal thickness (CT) and the choroidal vascularity index (CVI) in patients with optic disc drusen (ODD).

METHODS

This cross-sectional study examined the eyes of 17 patients with ODD and 18 healthy control subjects. The CT values were calculated manually from the images captured by enhanced depth imaging-optical coherence tomography (EDI-OCT). The CVI was defined as the proportion of the vascular area to the total choroidal area at the subfoveal and peripapillary areas after binarization of the EDI-OCT images.

RESULTS

It was found that the mean subfoveal CVI value in the ODD group was significantly lower than that in the control group (p = 0.006). The mean peripapillary CVI values were significantly lower in all of the quadrants in the ODD group when compared with the control group (p = 0.008 for the temporal quadrant, p = 0.014 for the nasal quadrant, p = 0.024 for the superior quadrant, and p = 0.038 for the inferior quadrant). Regarding the CT, there were no significant differences in the subfoveal and peripapillary CT values between the ODD group and the control group (p >  0.05 for all values).

CONCLUSION

The findings of this study indicate ODD to be associated with decreased subfoveal and peripapillary CVI, even though the subfoveal and peripapillary CT values were within the normal range. This result may prove important in relation to identifying a choroidal vascular network that appears to be morphologically normal but microstructurally impaired due to ODD. Further studies are required to verify the significance of CVI in the pathogenesis and complications of ODD.

Volumetric quantification of choroid and Haller's sublayer using OCT scans: An accurate and unified approach based on stratified smoothing

BACKGROUND AND OBJECTIVE

The choroid, a dense vascular structure in the posterior segment of the eye, maintains the health of the retina by supplying oxygen and nutrients, and assumes clinical significance in screening ocular diseases including age-related macular degeneration (AMD) and central serous chorioretinopathy (CSCR). As a technological assist, algorithmic estimation of choroidal biomarkers has been suggested based on sectional (B-scan) optical coherence tomography (OCT) images. However, most such 2D estimation techniques are compute-intensive, yet enjoy limited accuracy and have only been validated on OCT image datasets of healthy eyes. Not surprisingly, fine-scale analyses, including those involving Haller's sublayer, remain relatively rare and unsophisticated. Against this backdrop, we propose an efficient algorithm to quantify desired biomarkers with improved accuracy based on volume OCT scans. Specifically, we attempted an accurate, computationally light volumetric segmentation method involving stratified smoothing to detect choroid and Haller's sublayer.

METHODS

For detecting the various boundaries of the choroid and the Haller's sublayer, we propose a common volumetric method that performs suitable exponential enhancement and maintains smooth spatial continuity across 2D B-scans. Further, we achieve suitable volumetric smoothing by primarily deploying light-duty linear regression, and sparingly using compute-intensive tensor voting, and hence significantly reduce overall complexity. The proposed methodology is tested on five health and five diseased OCT volumes considering various metrics including volumetric Dice coefficient and corresponding quotient measures to facilitate comparison vis-à-vis intra-observer repeatability.

RESULTS

On five healthy and five diseased OCT volumes, respectively, the proposed method for choroid segmentation recorded volumetric Dice coefficients of 93.53 % and 93.30 %, which closely approximate the respective reference observer repeatability values of 95.60 % and 95.49 %. In terms of related quotient measures, our method achieved more than 50 % improvement over a recently reported method. In detecting Haller's sublayer as well, our algorithm records statistical performance closely matching that of reference manual method.

CONCLUSION

Advancing the state-of-the-art, the proposed volumetric segmentation, tested on both healthy and diseased datasets, demonstrated close match with the manual reference. Our method assumes significance in accurate screening of chorioretinal diseases including AMD, CSCR and pachychoroid. Further, it enables generating accurate training data for developing deep learning models for improved detection of choroid and Haller's sublayer.

Effects of long-term high-altitude exposure on retinal and choroidal microcirculation

PURPOSE

To quantify the effect of long-term high-altitude (HA) exposure on retinal and choroidal microcirculation and to relate these changes to high-altitude polycythemia (HAPC), as a proxy for etiopathogenesis of high-altitude related retinopathy (HAR).

METHODS

Fifty-one HAPC patients, 50 healthy HA residents, and 43 low altitude (LA) residents were recruited in this study. Optical coherence tomography angiography (OCTA) and enhanced depth imaging (EDI)-OCT images were analyzed. Retinal microvascular metrics included vessel density (VD), skeleton density (SD), fractal dimension (FD), and foveal avascular zone (FAZ). Choroidal microvascular metrics included subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI). All metrics were calculated by ImageJ software and compared among HAPC group, healthy HA group, and LA group.

RESULTS

In HAPC group, VD (30.62 ± 3.67%), SD (13.25 ± 1.64%), FD (1.79 ± 0.04), and the CVI (63.01 ± 1.42%) were significant lower and SFCT (403.25 ± 94.3 μm) was significant thicker than healthy HA group (all P < 0.001). FAZ area was comparable between two groups (0.42 ± 0.1 vs. 0.4 ± 0.11 mm², P = 0.411). However, these metrics were not different between healthy HA group and LA group (all P > 0.05) except for FD was lower in HA group (P < 0.001). Pearson's correlation analyses revealed HGB was negatively related with VD (r =  - 0.562, P < 0.001) and positively related with SFCT (r = 0.505, P < 0.001) in healthy HA group; however, no associations between HGB and vascular metrics in HAPC group were detected (all P > 0.05).

CONCLUSIONS

Long-term exposure to HA environment induces retinal and choroidal microcirculation disturbance in HAPC patients. However, these changes were not evident in healthy HA residents because of adaptation.

Baseline Sattler Layer-Choriocapillaris complex Thickness cutoffs associated with age-related macular degeneration progression

PURPOSE

This study aims to assess the relationship between choroidal overall and sublayer thickness and AMD stage progression.

METHODS

A prospective, observational case series was performed. 262 eyes of 262 patients with different stages of AMD were imaged by Optical Coherence Tomography (OCT). AMD stage, choroidal thickness (CT), Sattler layer-choriocapillaris complex thickness (SLCCT) and Haller layer thickness (HLT) were determined at the baseline visit, at a 1-year follow-up visit, at a 2-year follow up visit and at a final visit (performed after a mean of 5 ± 1 years from the baseline visit).

RESULTS

Baseline AMD stages were distributed as follows: early AMD (30 eyes; 12%), intermediate AMD (97 eyes; 39%) and late AMD (126 eyes; 49%). At the final follow-up, AMD stages were so distributed: early AMD (14 eyes; 6%), intermediate AMD (83 eyes; 33%) and late AMD (156 eyes; 61%). Each group showed a statistically significant decrease in CT values over the entire follow-up (p <0.001) and SLCCT reduction was associated with AMD progression (p <0.001). Moreover, SLCCT quantitative cutoffs <20.50 µm and <10.5 µm were associated with a moderate and high probability of AMD progression, respectively, and SLCCT quantitative cutoffs <18.50 µm and <8.50 µm implied a moderate and high probability of macular neovascularization (MNV) onset, respectively.

CONCLUSIONS

Progressive choroidal impairment contributes to AMD progression. Among choroidal layers, a reduced SLCCT is a promising biomarker of disease worsening and its quantitative evaluation could help to identify patients at higher risk of stage advancement.

Choroidal vascularity index change in macular telangiectasia type 2

Purpose

To analyze choroidal structure using subfoveal choroidal thickness (SFCT) and choroidal vascularity index (CVI) in Macular Telangiectasia (MacTel) type 2.

Methods

Medical records of 43 eyes with MacTel type 2 and 30 sex and age-matched healthy eyes were retrospectively reviewed. Their SFCT and CVI were measured using the SS-OCT scan passing through the central fovea and image binarization. The difference in baseline SFCT and CVI from each group and their yearly changes up to second year of follow up were analyzed. The baseline characteristics of the groups were also compared.

Results

The baseline characteristics, including CVI and SFCT, of the MacTel group and the control group were not significantly different, except for BCVA. The mean CVI of MacTel group were 64.59 ± 2.92%, 63.76 ± 2.67%, and 62.97 ± 2.74% (p < 0.001) whereas that of control group were 63.33 ± 2.45%, 63.04 ± 2.46%, and 63.43 ± 2.25% (p = 0.636) at baseline, 1 and 2 years, respectively. The mean SFCT of MacTel group were 324.65 ± 89.65μm, 326.14 ± 93.11μm, and 322.65 ± 91.77μm (p = 0.436), whereas that of control group were 304.30 ± 51.86 μm, 300.86 ± 52.64μm, and 298.55 ± 53.71μm (p = 0.275) at baseline, 1 and 2 years, respectively.

Conclusion

CVI decreases at a faster rate in MacTel type 2 in comparison with healthy subjects. This may suggest possible choroidal involvement in the progression of MacTel type 2.

Three-dimensional modelling of the choroidal angioarchitecture in a multi-ethnic Asian population

This study aimed to describe the topographic variation of the macula's choroidal angioarchitecture using three-dimensional (3D) choroidal vascularity index (CVI) of healthy eyes from an Asian population and to investigate the associations of CVI. 50 participants were recruited via stratified randomisation based on subfoveal choroidal thickness from the Singapore Epidemiology of Eye Diseases Study. Macular volume scans were acquired using spectral-domain optical coherence tomography with enhanced depth imaging. CVI was assessed based on B-scan binarisation and choroid segmentation. The 3D CVI of the whole, superior, central, and inferior macula were 62.92 ± 1.57%, 62.75 ± 1.93%, 63.35 ± 1.72%, and 62.66 ± 1.70%, respectively, pairwise comparisons P all > 0.05). 3D CVI (Whole Macula) and 2D CVI (Subfoveal) were associated only with each other and not with other ocular and systemic factors. 2D CVI (Subfoveal) had a moderate agreement with 3D CVI (Central Macula) [intraclass corelation coefficient (ICC) = 0.719], and had poorer agreement with 3D CVI of the whole macula, superior, and inferior macula (ICC = 0.591, 0.483, and 0.394, respectively). Scanning volume did not influence 3D CVI measurements. In conclusion, 3D CVI demonstrated no significant topographic variation. CVI was not correlated with demographic or ocular structural features. 2D CVI of the fovea is partially representative of 3D CVI of the macula.

Correlation of Renal Profiles with Choroidal Vascularity Index in Eyes with Diabetic Retinopathy

The vascular system is affected by systemic conditions, including diabetes, hypertension, and cardiovascular disease. The choroid is an important vascular tissue surrounding the sensory retina. However, the relationship between the choroid and systemic factors in patients with diabetes has rarely been investigated. Here, we assessed the correlation of renal profiles with choroidal vasculature in eyes with diabetic retinopathy (DR) using a retrospective study design. The study included 131 patients with diabetes who underwent swept-source optical coherence tomography and routine medical work-up within a 4-week period between 1 February 2016 and 30 October 2018. Consecutive patients with treatment-naïve DR who did not receive any subsequent treatment were included. The distribution of patients according to the DR stage was as follows: no DR, 32 patients; mild-to-moderate non-proliferative DR (NPDR), 33 patients; severe NPDR, 34 patients; and treatment-naïve proliferative DR, 32 patients. Multivariate regression analyses showed that the choroidal vascularity index (CVI) of naïve eyes with DR was negatively correlated with age (p = 0.013) and the serum levels of phosphorus (p = 0.002) and positively correlated with subfoveal choroidal thickness (p < 0.001). Taken together, our findings suggest that a lower CVI is associated with phosphorus retention in patients with chronic kidney disease.

Long-term effect of intravitreal aflibercept treatment on choroidal vascularity index in neovascular age-related macular degeneration

BACKGROUND

Our aim is to examine the effect of intravitreal aflibercept treatment on the choroidal vascularity index in eyes with neovascular age-related macular degeneration (nARMD) using the binarization method.

METHODS

Included in the study were the 38 eyes of 38 patients diagnosed with nARMD and treated with intravitreal aflibercept at our clinic. The patients' 12-month records were reviewed retrospectively. Patients' choroidal thickness (CT) was measured at baseline, 3rd month, 6th month, and 12th month on EDI-OCT images. We calculated luminal area (LA), stromal area (SA), total choroidal area (TCA), and choroid vascular index (CVI) values using binarization.

RESULTS

The mean age of the patients was 70,1 ± 8 years. The mean of injections over 12 months was 5.6 ± 2. Baseline values were CT 224 µm, LA 0,214 mm², SA 0,119mm², TCA 0,333 mm², and CVI 64% respectively. At the 3rd month, values were CT 223 µm, LA 0,212 mm², SA 0,121 mm², TCA 0,332 mm², and CVI 64%, respectively. The 6th-month values were CT 221 µm, LA 0,204 mm², SA 0,116 mm², TCA 0,320 mm², and CVI 64%, respectively, and 12-month values were CT 218 µm, LA 0,204 mm², SA 0,112 mm², TCA 0,318 mm², and CVI 64%, respectively. According to LogMAR, BCVA was 0.59 at baseline, 0.56 at 3 months, 0.52 at 6 months, and 0.51 at 12 months. At the end of month 12, we observed a statistically significant decrease in CT. No significant changes were observed in other parameters. When the number of injections was correlated with CVI, CT, and BCVA, a significant negative correlation was observed with CVI CONCLUSIONS: Aflibercept treatment reduces CT by affecting not only luminal but also stromal areas of the choroid in the long term but does not change the CVI. However, as the number of injections increases, CVI decreases.

Increased Systemic C-Reactive Protein Is Associated With Choroidal Thinning in Intermediate Age-Related Macular Degeneration

Purpose

C-reactive protein (CRP) and decreased choroidal thickness (CT) are risk factors for progression to advanced age-related macular degeneration (AMD). We examined the association between systemic levels of CRP and CT in patients with intermediate AMD (iAMD).

Methods

Patients with iAMD in the Colorado AMD Registry were included. Baseline serum samples and multimodal imaging including spectral domain–optical coherence tomography (SD-OCT), fundus photography, and autofluorescence were obtained. Medical and social histories were surveyed. CT was obtained by manual segmentation of OCT images. High-sensitivity CRP levels were quantified in serum samples. Univariate and multivariable linear regression models accounting for the intrasubject correlation of two eyes were fit using log-transformed CT as the outcome.

Results

The study included 213 eyes from 107 patients with a mean age of 76.8 years (SD, 6.8). Median CT was 200.5 µm (range, 86.5–447.0). Median CRP was 1.43 mg/L (range, 0.13–17.10). Higher CRP was associated with decreased CT in the univariate model (P = 0.01). Older age and presence of reticular pseudodrusen (RPD) were associated with decreased CT (P < 0.01), whereas gender, body mass index, and smoking were not associated with CT. Higher CRP remained significantly associated with decreased CT after adjustment for age and RPD (P = 0.01).

Conclusions

Increased CRP may damage the choroid, leading to choroidal thinning and increased risk of progression to advanced AMD. Alternatively, CRP may be a marker for inflammatory events that mediate ocular disease. The results of this study further strengthen the association between inflammation and AMD.

Translational Relevance

Increased CRP is associated with choroidal thinning, a clinical risk factor for AMD.

CHOROIDAL IMAGING BIOMARKERS TO PREDICT HIGHLY RESPONSIVE AND RESISTANT CASES TREATED WITH STANDARDIZED ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR REGIMEN IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

To determine structural predictors of treatment response in neovascular age-related macular degeneration analyzing optical coherence tomography (OCT)-related biomarkers.

METHODS

A retrospective review of patients undergoing treatment for neovascular age-related macular degeneration at a tertiary institute was performed at presentation. High-intensity regimen included eyes on long-term anti-vascular endothelial growth factor treatment with the inability to extend beyond a month without a relapse and needed double the dose of medication (n = 25). Low-intensity regimen had eyes that went into long-term remission after at least three injections and remained dry for more than a year until the last visit (n = 20). Multimodal imaging including fluorescein angiogram, OCT, and comprehensive ocular evaluation were done. Choroidal vascularity index, total choroidal area, luminal area, subfoveal choroidal thickness, choriocapillaris thickness and Haller and Sattler layer thickness were analyzed for statistical significance.

RESULTS

The groups had no significant difference at baseline in age, gender, incidence of reticular pseudodrusen, polypoidal choroidal vasculopathy feature on OCT, type of choroidal neovascular membrane, and geographic atrophy. Multinomial logistic regression revealed that thicker subfoveal choroidal thickness and larger total choroidal area were the significant predictors of poor response to anti-vascular endothelial growth factor treatment (E = 0.02; P = 0.02; E = 1.82; P = 0.0075).

CONCLUSION

Thicker subfoveal choroidal thickness and higher total choroidal area are useful variables to predict a poor treatment response.

Choroidal vascularity index and choroidal thickness changes in patients with allergic asthma

BACKGROUND

This study aimed to investigate whether the choroidal vascularity index (CVI), choroidal thickness (ChT), and retinal nerve fiber thickness (RNFL) of patients with allergic asthma change compared to the healthy control group.

METHODS

This cross-sectional, observational study comprised 59 eyes of 59 patients with allergic asthma (Group 1) and 50 eyes of 50 age and sex-matched healthy volunteers as a control group (Group 2). CVI was measured by binarization of images obtained from choroidal enhanced depth imaging (EDI) mode optic coherence tomography. CVI was defined as the ratio of the choroidal luminal area to the total circumscribed choroidal area. ChT was measured manually at 3 points, subfoveal and 1000 microns nasal and temporal to the fovea (SFCT, N1000, and T1000 respectively). RNFL measurements were subdivided as global, nasal, temporal, superonasal, superotemporal, inferonasal, and inferotemporal quadrants.

RESULTS

Subfoveal CVI and ChT were significantly lower in asthma patients (p:0,043 and p: 0.034, respectively). N1000 and T1000 ChT and RNFL thicknesses were lower in asthma patients compared to the control group, though no significant difference was found between them (p> 0.05).

CONCLUSION

Our findings suggest that asthma patients have choroidal structural changes. In the literature, there are not enough studies regarding the effects of asthma on ocular parameters.

Choroidal structural changes determined by the binarization method after intravitreal aflibercept treatment in neovascular age-related macular degeneration

AIM

To assess the choroidal structural alterations after intravitreal injection of aflibercept in neovascular age-related macular degeneration (nAMD).

METHODS

Fifty eyes with treatment-naïve nAMD were evaluated at baseline, 3^rd, and 12^th month. Fifty eyes of 50 healthy subjects were also included as controls. Choroidal thickness (CT) was measured in the subfoveal region. Total circumscribed choroidal area (CA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI) was calculated using Image J.

RESULTS

At baseline, subfoveal CT was increased in nAMD patients compared to controls (P=0.321). Eyes with nAMD had a significantly increased total circumscribed CA and SA (P=0.041, 0.005, respectively). The CVI was decreased (P=0.038). In the 3^rd month, the subfoveal CT, LA, and CVI revealed a decrease (P=0.005, P=0.039, 0.043, respectively). In the 12^th month, subfoveal CT, LA, and CVI were decreased in comparison to baseline measures (P<0.001, 0.006, 0.010, respectively).

CONCLUSION

Significant structural alterations are found after intravitreal aflibercept treatment during the 12-month follow-up, in particular at the third month, in eyes with nAMD.

The impact of vascular risk factors on the thickness and volume of the choroid in AMD patients

Disturbances in choroidal microcirculation may lead to the onset and progression of age-related macular degeneration (AMD). We aimed to assess changes in the choroidal volume and thickness in the macular region in AMD eyes and to investigate whether coexisting vascular risk factors alter choroidal status. We enrolled 354 AMD patients (175 dry, 179 wet AMD) and 121 healthy controls. All participants underwent a complete ophthalmologic examination and assessment of choroidal thickness and volume. A multivariate analysis adjusted for age, sex, and smoking status revealed that wet AMD was an independent factor associated with higher average thickness of the central ring area (ATC) and average volume of the central ring area (AVC) and lower choroidal vascularity index (CVI) compared to controls (β =  + 0.18, p = 0.0007, β =  + 0.18, p = 0.0008, respectively) and to dry AMD (β =  + 0.17, p = 0.00003 for both ATC and AVC and β =  - 0.30 p < 0.0001 for CVI). ATC, AVC and average volume (AV) were lower in AMD patients with hypertension and ischaemic heart disease (IHD). The duration of hypertension was inversely correlated with ATC, AVC and AV (Rs =  - 0.13, p < 0.05; Rs =  - 0.12; p < 0.05, Rs =  - 0.12; p < 0.05, respectively) while IHD duration negatively correlated with AV (Rs =  - 0.15, p < 0.05). No such associations were observed in the control group. Our findings show that the choroidal vascular system in eyes with AMD is much more susceptible to damage in the presence than in the absence of systemic vascular disease.

Exploring the choroidal vascular labyrinth and its molecular and structural roles in health and disease

The choroid is a key player in maintaining ocular homeostasis and plays a role in a variety of chorioretinal diseases, many of which are poorly understood. Recent advances in the field of single-cell RNA sequencing have yielded valuable insights into the properties of choroidal endothelial cells (CECs). Here, we review the role of the choroid in various physiological and pathophysiological mechanisms, focusing on the role of CECs. We also discuss new insights regarding the phenotypic properties of CECs, CEC subpopulations, and the value of measuring transcriptomics in primary CEC cultures derived from post-mortem eyes. In addition, we discuss key phenotypic, structural, and functional differences that distinguish CECs from other endothelial cells such as retinal vascular endothelial cells. Understanding the specific clinical and molecular properties of the choroid will shed new light on the pathogenesis of the broad clinical range of chorioretinal diseases such as age-related macular degeneration, central serous chorioretinopathy and other diseases within the pachychoroid spectrum, uveitis, and diabetic choroidopathy. Although our knowledge is still relatively limited with respect to the clinical features and molecular pathways that underlie these chorioretinal diseases, we summarise new approaches and discuss future directions for gaining new insights into these sight-threatening diseases and highlight new therapeutic strategies such as pluripotent stem cell‒based technologies and gene therapy.

Analysis of the Peripapillary Choroidal Vascular Characteristics in Papilledema Associated with Pseudotumor Cerebri

SIGNIFICANCE

Choroidal vascularity index measured by image binarization method from peripapillary optical coherence tomography sections has been found significantly lower in papilledema patients than healthy controls.

PURPOSE

The purpose of this study was to compare peripapillary choroidal parameters in papilledema patients with control subjects.

METHODS

Peripapillary spectral domain optical coherence tomography scans of 34 patients with papilledema and 34 healthy controls are acquired for the study. Images are binarized with the ImageJ software (National Institutes of Health, Bethesda, MD) to calculate total choroidal area, stromal area, luminal area, and choroidal vascularity index.

RESULTS

Total choroidal area, luminal area, and choroidal vascularity were significantly lower in papilledema patients compared with healthy controls on right (1.343 ± 0.286 vs. 1.694 ± 0.344, P < .001; 0.880 ± 0.209 vs. 1.167 ± 0.255, P < .001; 65.28 ± 2.99% vs. 68.68 ± 2.81%, P < .001, respectively) and left eyes (1.376 ± 0.308 vs. 1.647 ± 0.339, P < .001; 0.899 ± 0.231 vs. 1.134 ± 0.237, P < .001; 64.92 ± 3.44 vs. 68.84 ± 3.23, P < .001, respectively). No difference was found between active and remitted stages of papilledema in terms of choroidal parameters.

CONCLUSIONS

Peripapillary total choroidal area, luminal area, and choroidal vascularity index are significantly reduced in patients with papilledema. These parameters might be beneficial tools for evaluating choroidal vascularity in papilledema quantitatively and differential diagnosis for optic disc edema.

Pentosan Polysulfate Maculopathy: Prevalence, Spectrum of Disease, and Choroidal Imaging Analysis Based on Prospective Screening

PURPOSE

To describe the prevalence and spectrum of disease of pentosan polysulfate (PPS) maculopathy in a large multimodal retinal imaging study and to report the results of choroidal vascularity index (CVI) analysis.

DESIGN

Prospective cohort study Methods: Of 741 patients prescribed PPS within a large university database, 100 (13.4%) with any consumption agreed to participate in a prospective screening investigation. Multimodal retinal imaging including near-infrared reflectance (NIR), fundus autofluorescence (FAF), and spectral domain optical coherence tomography (SD-OCT) was performed in all patients. Characteristic findings of affected patients were identified, and affected and unaffected cohorts were compared. CVI, defined as stromal choroidal area (SCA) divided by the total choroidal area, was analyzed.

RESULTS

The prevalence of PPS maculopathy was 16%. NIR illustrated punctate hyperreflective lesions with early presentation. FAF illustrated a speckled macular network of hypo- and hyperautofluorescence colocalized with multifocal hyperreflective retinal pigment epithelial lesions on SD-OCT. Advanced cases demonstrated varying degrees of atrophy. The affected cohort exhibited significantly greater mean PPS therapy duration, mean daily dosage, and mean cumulative dosage (19.5±5.5 years, 433.9±137.6 mg, 3,103.1±1,402.2 g) compared with the unaffected cohort (7.1±6.6 years, 291.6±177.6 mg, 768.4±754.8 g). SCA was significantly lower and CVI was significantly greater in the affected vs the unaffected group.

CONCLUSIONS

This prospective cohort study identified a prevalence of PPS maculopathy of 15%-20% among PPS users who agreed to participate. A spectrum of findings may be observed with multimodal retinal imaging. Significant choroidal abnormalities associated with this characteristic maculopathy may provide surrogate markers of macular toxicity.

USE OF CHOROIDAL VASCULARITY INDEX FOR CHOROIDAL STRUCTURAL EVALUATION IN CENTRAL SEROUS CHORIORETINOPATHY WITH CHOROIDAL NEOVASCULARIZATION

PURPOSE

To evaluate choroidal vascular structure in eyes with central serous chorioretinopathy (CSC) by assessing the choroidal vascular index (CVI).

METHODS

We retrospectively analyzed the medical records of 117 eyes with CSC. Subjects were divided into 4 groups according to clinical characteristics: 1) acute CSC (N = 29), 2) non-neovascularized chronic CSC without flat irregular pigment epithelial detachment (N = 49), 3) non-neovascularized chronic CSC with flat irregular pigment epithelial detachment (N = 21), and 4) chronic CSC with choroidal neovascularization (N = 18). Subfoveal choroidal area (1,500 mm) of swept source optical coherence tomography scans were divided into luminal and stromal areas by the image binarization technique. The CVI was defined as the ratio of the luminal to the total subfoveal choroidal area.

RESULTS

The CVI was significantly lower in eyes of Group 4 than those of other groups (all P < 0.05). The subfoveal choroidal thickness was significantly lower in Group 4 than in Groups 1 and 2 (P < 0.05), but regression analysis showed no association with the CVI.

CONCLUSION

Decreased CVI may reflect choroidal vascular structure changes in eyes with choroidal neovascularization complicating CSC. These findings suggest that the CVI could be useful for evaluating choroidal vascular changes in eyes with CSC.

Foveal Avascular Zone and Choroidal Thickness Are Decreased in Subjects with Hard Drusen and without High Genetic Risk of Developing Alzheimer's Disease

A family history (FH+) of Alzheimer’s disease (AD) and ɛ4 allele of the ApoE gene are the main genetic risk factors for developing AD, whereas ɛ4 allele plays a protective role in age-related macular degeneration. Ocular vascular changes have been reported in both pathologies. We analyzed the choroidal thickness using optical coherence tomography (OCT) and the foveal avascular zone (FAZ) using OCT-angiography and compared the results with ApoE gene expression, AD FH+, and the presence or absence of hard drusen (HD) in 184 cognitively healthy subjects. Choroidal thickness was statistically significantly different in the (FH−, ɛ4−, HD+) group compared with (i) both the (FH−, ɛ4−, HD−) and the (FH+, ɛ4+, HD+) groups in the superior and inferior points at 1500 μm, and (ii) the (FH+, ɛ4−, HD+) group in the superior point at 1500 μm. There were statistically significant differences in the superficial FAZ between the (FH+, ɛ4−, HD+) group and (i) the (FH+, ɛ4−, HD−) group and (ii) the (FH+, ɛ4+, HD−) group. In conclusion, ocular vascular changes are not yet evident in participants with a genetic risk of developing AD.

Relationship between proteinuria and optical coherence tomographic features of the chorioretina in patients with pre-eclampsia

This retrospective study aimed to evaluate the correlation between ophthalmologic factors and proteinuria in patients with pre-eclampsia using swept-source optical coherence tomography (OCT) and OCT angiography. In total, 61 pregnant patients diagnosed with pre-eclampsia were recruited during their hospital stay. The authors investigated the relationship between urine protein–creatinine ratio (PCR) and chorioretinal measurements including choroidal thickness (CT), choroidal vascularity index (CVI), foveal avascular zone (FAZ), vascular density (VD), ganglion cell layer+ (GCL+) and GCL++. The associations between mean arterial pressure (MAP) and ophthalmologic factors were also evaluated. Central subfield CT of the right eye (p = 0.031) and paracentral CT of both eyes were related to higher PCR (≥1.35 mg/mg). A significant association with PCR after logarithm transformation was noted (r = 0.284, p = 0.026). Retinal measurements (FAZ, VD, GCL+ and GCL++) and CVI were not related with PCR. There was a positive association between MAP and PCR after logarithm transformation (r = 0.296, p = 0.021); however, chorioretinal factors were not related with MAP. In pregnant women with pre-eclampsia, CT using OCT is a novel factor that is correlated with PCR. Ocular structural alteration in patients with pre-eclampsia may be one of systemic vascular changes caused by pre-eclampsia rather than hypertension.

TOPOGRAPHIC CHANGES IN CHOROIDAL THICKNESS IN AGE-RELATED MACULAR DEGENERATION DURING THE DEVELOPMENT OF ACTIVE CHOROIDAL NEOVASCULARIZATION

PURPOSE

To evaluate topographic changes in choroidal thickness during development of choroidal neovascularization (CNV) in treatment-naive age-related macular degeneration (AMD) and to test the value of such changes as a predictive tool of CNV development.

METHODS

This retrospective cohort included 86 eyes that developed CNV from intermediate AMD, 43 eyes with intermediate AMD, and 36 eyes without AMD. Patients with intermediate AMD underwent spectral domain optical coherence tomography using enhanced depth imaging mode every 6 months until CNV was detected. Choroidal neovascularization was localized to one of the subfields of Early Treatment of Diabetic Retinopathy Study grid on fluorescein angiography. Average choroidal thickness of each subfield was calculated.

RESULTS

Choroidal thickness of the subfield where CNV developed at first clinical detection significantly increased compared with that 6 months before (P = 0.000 for central, P = 0.001 for superior parafoveal, P = 0.002 for temporal parafoveal, P = 0.002 for inferior parafoveal, and P = 0.001 for nasal parafoveal subfield). In eight patients who visited unexpectedly 3 months before CNV development in central subfield, choroidal thickness of central subfield increased significantly compared with that 6 months before CNV development (P = 0.001).

CONCLUSION

Choroidal neovascularization development accompanied choroidal thickening of the corresponding subfield. Regular measurement of choroidal thickness may assist in prediction of CNV.

Choroidal vascularity index: a step towards software as a medical device

The choroidal vascularity index (CVI) is a relatively new parameter, calculated off optical coherence tomography (OCT) images, for the quantitative evaluation of choroid vascularity. It is defined as the ratio of vascular area to the total choroidal area, presented as a percentage. The choroid is an important vascular bed, often implicated in ocular and systemic conditions. Since the introduction of CVI, multiple studies have evaluated its efficacy as a tool for disease prognostication and monitoring progression, with promising results. The CVI was born out of the need for more robust and accurate evaluations of choroidal vasculature, as prior parameters such as choroidal thickness and choroidal vessel diameter had their limitations. In this review, we summarise current literature on the CVI, explain how the CVI is derived and explore its potential integration into future research and translation into clinical care. This includes the application of CVI in various disease states, and ongoing attempts to produce an automated algorithm which can calculate CVI from OCT images.

Microfluidic organ-on-a-chip model of the outer blood-retinal barrier with clinically relevant read-outs for tissue permeability and vascular structure

The outer blood-retinal barrier (oBRB) tightly controls the transport processes between the neural tissue of the retina and the underlying blood vessel network. The barrier is formed by the retinal pigment epithelium (RPE), its basal membrane and the underlying choroidal capillary bed. Realistic three-dimensional cell culture based models of the oBRB are needed to study mechanisms and potential treatments of visual disorders such as age-related macular degeneration that result from dysfunction of the barrier tissue. Ideally, such models should also include clinically relevant read-outs to enable translation of experimental findings in the context of pathophysiology. Here, we report a microfluidic organ-on-a-chip model of the oBRB that contains a monolayer of human immortalized RPE and a microvessel of human endothelial cells, separated by a semi-permeable membrane. Confluent monolayers of both cell types were confirmed by fluorescence microscopy. The three-dimensional vascular structures within the chip were imaged by optical coherence tomography: a medical imaging technique, which is routinely applied in ophthalmology. Differences in diameters and vessel density could be readily detected. Upon inducing oxidative stress by treating with hydrogen peroxide (H₂O₂), a dose dependent increase in barrier permeability was observed by using a dynamic assay for fluorescence tracing, analogous to the clinically used fluorescence angiography. This organ-on-a-chip of the oBRB will allow future studies of complex disease mechanisms and treatments for visual disorders using clinically relevant endpoints in vitro.

Choroidal vascular changes in age-related macular degeneration: A protocol for systematic review and meta-analysis

BACKGROUND

As an increasing age-related eye disease, age-related macular degeneration (AMD) is becoming a common cause of irreversible visual loss in elder population. The mechanism of AMD remains uncertain and covers a complex risk factors. Choroidal vascularity index (CVI) is a sensitive parameter obtained by enhanced depth imaging of optical coherence tomography which allows the choroid in more detail and accurate assessment in the pathogenesis of AMD. The objective of this current study is to evaluate choroidal structural alternations measured by CVI in AMD.

METHODS

We will review 4 English databases (PubMed, Embase, Cochrane Library, and Web of Science) from their inception until present to select eligible articles. English-language and case-control studies will be accepted. The data extraction content and quantitative analysis will be performed systematically by 2 independent authors. The primary outcome is the alternation of CVI in AMD. The secondary outcomes consist of choroidal thickness (CT), luminal area (LA), stromal area (SA), and total choroidal area (TCA). Subgroup analysis, sensitivity analysis, and publication bias will be performed to check the robustness of the pooled outcome data.

RESULTS

Changes of quantitative parameters such as CVI will be obtained in patients with AMD.

CONCLUSION

This study will elucidate alternations of choroidal vascular and stromal component in AMD and provide robust evidence on the pathophysiology of AMD.

REGISTRATION NUMBER

INPLASY.

Choroidal Structural Changes Assessed with Swept-Source Optical Coherence Tomography after Cataract Surgery in Eyes with Diabetic Retinopathy

Objective

To determine the influence of phacoemulsification on choroidal vasculature in patients with diabetic retinopathy (DR) undergoing cataract surgery using swept-source optical coherence tomography (SS-OCT).

Methods

The study was conducted in 23 eyes of 23 cataract patients with mild/moderate nonproliferative diabetic retinopathy (NPDR) without diabetic macular edema (DME) and 23 age-matched controls. Choroidal thickness (CT) and choroidal vascularity index (CVI) were measured at baseline and 1 week, 1 month, and 3 months after surgery.

Results

The baseline CVI in the DR group was significantly lower than that in the control group (P=0.001). CVI in DR patients after surgery significantly increased compared with preoperative values (all P < 0.001 for 1 week, 1 month, and 3 months after surgery). Postoperative increase of CVI and CT in the DR group was more than in the control group, and the difference was significant 1 month and 3 months after surgery (all P < 0.05).

Conclusion

Patients with mild/moderate NPDR have reduced CVI compared with nondiabetic patients at baseline; diabetic cataract surgery tended to induce more increase in CVI and CT as compared with nondiabetic patients. This trial is registered with NCT04499768.

Short-term choroidal vascular changes after aflibercept therapy for neovascular age-related macular degeneration

Introduction

The purpose of this study was to evaluate choroidal vascular changes in patients with neovascular age-related macular degeneration (nAMD) treated with aflibercept injection over a 3-month period.

Methods

Enhanced depth imaging optical coherence tomography scans of 60 eyes with treatment-naïve nAMD and 60 unaffected fellow eyes were retrospectively analyzed. Data was collected at baseline and after 3 monthly intravitreal injections of aflibercept. The ImageJ software was used to binarize OCT scans and measure total choroid area (TCA), luminal area (LA), and stromal area (SA). Choroidal vascularity index (CVI) was defined as the ratio of LA to TCA.

Results

After treatment, subfoveal choroidal thickness (CT) in nAMD eyes significantly decreased from 210. 6 ± 61.6 to 194.6 ± 58.7 μm (P < 0.001), TCA from 1.620 ± 0.502 to 1.500 ± 0.451 mm² (P < 0.001), LA from 1.075 ± 0.335 to 0.985 ± 0.307 mm² (P < 0.001), SA from 0.545 ± 0.176 to 0.516 ± 0.153 mm² (P = 0.005), and CVI from 66.36 ± 2.89 to 65.46 ± 2.87% (P = 0.009). The decrease of CVI after treatment was significantly correlated with baseline CVI (Rs = 0.466, P < 0.001), but not with the change in BCVA and presence of dry macula after treatment (always P > 0.05).

Conclusion

Choroidal thickness and vascularity significantly decreased after treatment with aflibercept in nAMD eyes. Besides the pharmacologic effect on the neovascular lesion, aflibercept may induce vascular changes also on the underlying choroid.

Normal aging changes in the choroidal angioarchitecture of the macula

The choroidal vascularity index (CVI) has been shown to be sensitive in detecting changes in choroidal angioarchitecture in a range of ocular diseases. However, changes in CVI in association with normal physiological aging and spatial distribution remains to be determined. This is significant as a range of ocular conditions with choroidal degeneration are associated with aging. In this study, we assessed CVI for 106 healthy eyes from 106 individuals (range 21–78 years old, ~ 20 individuals/decade) at 15 eccentricities across the macula (0, 230 µm, 460 µm, 690 µm, 1,150 µm, 1,380 µm and 2,760 µm from the fovea in the superior and inferior direction). Total choroidal area, luminal area and stromal area were all significantly decreased with age (p < 0.001 for all parameters). CVI was also significantly decreased with age (p < 0.01) and eccentricity. Fitting of quadratic regression curves to CVI as a function of age yielded a good fit for all eccentricities (r² = 0.55–0.80) and suggested a decrease in CVI from the ages of 33–43 years at a rate of 0.7–2.7% per decade. CVI was lower in the inferior versus superior retina at matching eccentricities and a significant difference in age-related decline of CVI with eccentricity only occurred in inferior locations. These findings suggest choroidal angioarchitecture declines from the 4th decade of life with potential eccentricity differences in the inferior and superior retina. Considering the number of age-related diseases with choroidal dysfunction, these results provide foundational knowledge to understand choroidal involvement in these diseases.

Imaging the Choroid: From Indocyanine Green Angiography to Optical Coherence Tomography Angiography

The choroid is the vascular structure nourishing the retinal pigment epithelium and the outer retina and it plays a key role in the homeostasis of the eye both under physiological and pathological conditions. In the last 20 years we have moved from "guessing" what was happening beyond the retinal pigment epithelium to actually visualize structural and functional changes of the choroid in vivo noninvasively. In this review we describe the state of the art of choroidal imaging, focusing on the multiple techniques available in the clinical and research setting including indocyanine green angiography, labeled-cells angiographies, optical coherence tomography (OCT), enhanced depth imaging, swept source OCT, and OCT angiography. In the first section of the article, we describe their main applications and the basic principles to interpret the imaging results. Increasing evidence suggests that the choroid is much more involved than we used to think in many pathological conditions from uveitis to intraocular tumors, from vascular diseases to age-related macular degeneration. All clinicians should hence know which is the most appropriate imaging investigation to explore the choroid in the disease they are dealing with and how to interpret the results. For this reason the second section of this review summarizes the best imaging approach and the most common findings visible on choroidal imaging in different diseases of the eye.

Choroidal Microvasculature Dropout is Associated with Generalized Choroidal Vessel Loss within the β-Parapapillary Atrophy in Glaucoma

PURPOSE

To determine whether eyes with open-angle glaucoma (OAG) and a localized choroidal microvasculature dropout (MvD) are associated with a greater degree of generalized choroidal vascular insufficiency within the β-parapapillary atrophy (β-PPA) than OAG eyes without MvD.

DESIGN

Retrospective cross-sectional study.

METHODS

This study included 100 OAG eyes with visual field (VF) loss confined to a single hemifield (50 with and 50 without MvD, matched for age [≤10 years ols], axial length [≤1 mm], and VF severity [≤1 dB]), as well as 50 healthy eyes. Using optical coherence tomography angiography, parapapillary choroidal vessel density (pCVD) was measured on en-face images of choroidal maps within the entire β-PPA after excluding the MvD area and hemi-sectors of the β-PPA. pCVDs were compared among the 3 groups. The relationships between pCVD outcomes and various clinical variables were assessed. Logistical regression analyses were performed to determine the clinical factors associated with the presence of MvD in eyes with OAG.

RESULTS

pCVDs corresponding to the VF-intact hemi-sectors and the entire β-PPA, excluding the MvD area, were significantly lower in eyes with MvD than in matched sectors of eyes without MvD. Multivariate linear regression analysis showed that the presence of MvD and greater MvD angular extent were independently associated with lower global pCVD in OAG eyes (all P < .05). Logistic regression analyses showed that lower pCVD was the only factor significantly associated with the presence of MvD.

CONCLUSIONS

Localized MvD was a strong predictor of generalized pCVD loss within the β-PPA in OAG eyes.