CHOROIDAL VASCULARITY INDEX: A Novel Optical Coherence Tomography Based Parameter in Patients With Exudative Age-Related Macular Degeneration

Techniques for imaging the choroid and choroidal blood flow in vivo

The choroid, which is a highly vascularized layer between the retina and sclera, is essential for supplying oxygen and nutrients to the outer retina. Choroidal vascular dysfunction has been implicated in numerous ocular diseases, including age-related macular degeneration, central serous chorioretinopathy, polypoidal choroidal vasculopathy, and myopia. Traditionally, the in vivo assessment of choroidal blood flow relies on techniques such as laser Doppler flowmetry, laser speckle flowgraphy, pneumotonometry, laser interferometry, and ultrasonic color Doppler imaging. While the aforementioned methods have provided valuable insights into choroidal blood flow regulation, their clinical applications have been limited. Recent advancements in optical coherence tomography and optical coherence tomography angiography have expanded our understanding of the choroid, allowing detailed visualization of the larger choroidal vessels and choriocapillaris, respectively. This review provides an overview of the available techniques that can investigate the choroid and its blood flow in vivo. Future research should combine these techniques to comprehensively image the entire choroidal microcirculation and develop robust methods to quantify choroidal blood flow. The potential findings will provide a better picture of choroidal hemodynamics and its effect on ocular health and disease.

Association of choroidal thickness and blood flow features with asymmetric axial lengths in children with unilateral myopic anisometropia

BACKGROUND

Considering that changes in the choroidal thickness are closely related to ocular growth, we studied the choroidal thickness (CT) and the blood flow features in children with unilateral myopic anisometropia (UMA) as well as investigating the relationship between choroidal changes and myopia.

METHODS

Subjective refractive, axial length (AL), and biometric parameters were measured in 98 UMA children (age: 8-15 years). CT and choroidal blood-flow features, including the choroidal vessel volume (CVV), choroidal vascularity index (CVI), and choriocapillaris perfusion area (CCPA), were measured through swept-source optical coherence tomography angiography. The macular region was categorized into four concentric circles of diameters 0-1 mm (central fovea), 1-3 mm (parafovea), 3-6 mm (perifovea), and 6-9 mm (extended), and further categorized into superior (S), inferior (I), temporal (T), and nasal (N) quadrants.

RESULTS

The aforementioned four regions of myopic eyes displayed significantly lower CT, CVV, and CVI than those of non-myopic eyes. CCPA changes differed across different regions of both the eyes (parts of N and T quadrants). There was an inverse association between CT and the interocular AL difference (central and other regions S, T quadrant). No correlation was noted between CVV and CVI with interocular AL difference. CT and CVV were positively correlated in the 0-6-mm macular region of myopic eyes (Spearman correlation coefficient = 0.763, P < 0.001).

CONCLUSIONS

In UMA children, CCT and blood flow may be related to myopia progression. A robust correlation between CT and CVV in the 0-6-mm macular region and reduced CT and diminished blood flow indicated an association with myopia.

Choroidal vascularity index in patients with computer vision syndrome combined with accommodative lead

BACKGROUND

This study aimed to investigate the choroidal vascularity index (CVI) in patients with computer vision syndrome (CVS) combined with accommodative lead.

METHODS

This retrospective case-control study enrolled patients diagnosed with CVS and accommodative lead at University-Town Hospital of Chongqing Medical University between July 2022 and May 2023. The control group included individuals without any ocular diseases. Ophthalmic assessments included basic visual acuity, refraction, ocular biometric parameters, and CVI.

RESULTS

A total of 85 participants were included in the study, with 45 in the CVS group and 40 in the control group. The central corneal thickness of CVS group was found to be significantly thinner compared to the control group in both the right eye (532.40±30.93 vs. 545.78±19.99 µm, P = 0.019) and left eye (533.96±29.57 vs. 547.56±20.39, P = 0.014). In comparison to the control group, the CVS group exhibited lower CVI in the superior (0.40±0.08 vs. 0.43±0.09, P = 0.001), temporal (0.40±0.08 vs. 0.44±0.10, P < 0.001), inferior (0.41±0.08 vs. 0.46±0.08, P < 0.001), and nasal (0.41±0.08 vs. 0.44±0.08, P = 0.001) quadrants. Similar differences were observed in all four quadrants within the 1-3 mm radius, and in the temporal (P = 0.004) and inferior (P = 0.002) quadrants within the 1-6 mm and 3-6 mm radii (all P < 0.05).

CONCLUSION

Compared to individuals without ocular issues, patients with CVS and accommodative lead were found to have thinner corneal central thickness and lower CVI.

Choroidal vascularity features of fundus tessellation in adults with high myopia

BACKGROUND

To investigate alterations in choroidal vascularity index among highly myopic adults with fundus tessellation, utilizing optical coherence tomography.

METHODS

Total of 143 highly myopic adults (234 eyes) with fundus tessellation were collected in this cross-sectional study, which was stratified into different lesion groups based on the novel tessellated fundus classification. Subfoveal choroidal thickness (SFCT), choroidal luminal area (LA), stromal area (SA), total choroidal area (TCA), and choroidal vascularity index (CVI) were analyzed utilizing optical coherence tomography (OCT) with enhanced depth imaging (EDI) mode, enabling precise quantification of these parameters.

RESULTS

Comparison analysis demonstrated notable distinctions in spherical equivalent (SE), axial length (AL), and SFCT across the four tessellation grades (p < 0.001). Analysis of the choroidal vascularity parameters, including LA, TCA, and CVI, demonstrated notable disparities across the four groups (p < 0.001), while no significant variations were observed in SA when comparing Grade 1 versus Grade 2, as well as Grade 2 versus Grade 3 (p > 0.05). Logistic regression analyses illustrated that the higher grade of tessellated exhibited a positive association with AL (OR = 1.701, p = 0.027), while negatively associated with SFCT (OR = 0.416, p = 0.007), LA (OR = 0.438, p = 0.010) and CVI (OR = 0.529, p = 0.004). Multiple regression analyses demonstrated a significant negative association between CVI and both SE and AL after adjusting for age, while positively associated with SFCT (p < 0.05).

CONCLUSION

Subtle choroidal vascularity changes may have a meaningful contribution to the development and progression of fundus tessellation. CVI and LA dramatically decreased during the early stages of tessellation development and maintained a relatively stable status when in the severe tessellated grades.

COMPARISON OF THE CHOROIDAL VASCULARITY INDEX MEASUREMENTS OF IMAGES ACQUIRED WITH DIFFERENT OPTICAL COHERENCE TOMOGRAPHY SCAN SCALE TYPES

PURPOSE

To evaluate the differences in choroidal vascularity index (CVI) measurements between images acquired at the 1:1 pixel scale and at the 1:1 µ m scale of the Heidelberg optical coherence tomography device.

METHODS

Forty-five healthy eyes of 45 healthy subjects were included for this study. Fovea-centered scans were obtained with an enhanced-depth imaging mode with a high-speed protocol scan. Each scan was exported in 3 different types: 1) 1:1 pixel scale type; 2) 1:1 µ m scale type (MST); and 3) 4×-magnified MST (4×MST; 400%-magnified 1:1 µ m images exported via screenshot). A comparison between CVI measurements based on the different scale types of optical coherence tomography images was conducted using the Bland-Altman analysis and intraclass correlation coefficient.

RESULTS

The image with the worst clarity was acquired via the MST, and the CVI was found to be higher in MST images (69.05 ± 3.21) compared with the other groups. The intraclass correlation coefficient between the CVI values of the 4×MST and pixel scale type images was 0.92, between those of the 4×MST and MST images was 0.33, and between those of the pixel scale type and MST images was 0.44.

CONCLUSION

The optical coherence tomography scale and export method type significantly influence the image resolution, CVI, and choroidal area measurements.

Comparison of choroidal thickness and choroidal vascular index in normotensive dippers and nondippers

OBJECTIVE

The aim of this study was to evaluate the choroidal thickness and choroidal vascular index in normotensive individuals with dipping and nondipping patterns.

METHODS

Patients who applied to the cardiology clinic for routine checkups and underwent 24-h blood pressure monitoring were included in our study. They were divided into two groups based on their dipper status. The patients in whom systolic blood pressure decreased during the nocturnal time by 10% or more of the daily blood pressure were defined as dippers. On the contrary, patients whose nocturnal systolic blood pressure decreased by less than 10% were defined as nondippers. Choroidal thickness and choroidal vascular index were measured by spectral-domain optical coherence tomography. Central macular thickness, retinal nerve fiber layer, and ganglion cell layer (GCL) analyses were also recorded.

RESULTS

In total, 35 patients with dipper pattern and 34 patients with nondipper pattern were recruited. The mean subfoveal choroidal thickness was 349.72±90 μm in the dipper group and 358.54±132.5 μm in the nondipper group. The groups had no significant difference in choroidal thickness, central macular thickness, retinal nerve fiber layer, and ganglion cell layer analyses. However, the choroidal vascular index was statistically significantly lower in the nondipper group when compared to the dipper group (0.61±0.02 vs. 0.64±0.02; p<0.001). Also, the choroidal vascular index was negatively correlated with subfoveal choroidal thickness in the nondipper group (Spearman; r=-0.419; p=0.033).

CONCLUSION

Our study showed that the choroidal vascular index was significantly lower in nondippers than in dippers. Nondipper individuals may be affected by vascular dysregulation, leading to alterations in the choroidal circulation.

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.

CHOROIDAL VASCULARITY AND VISUAL OUTCOMES IN MACULA-OFF RHEGMATOGENOUS RETINAL DETACHMENT

PURPOSE

To investigate the association between visual outcomes and choroidal changes in patients with macula-off rhegmatogenous retinal detachment.

METHODS

This study retrospectively reviewed 63 eyes of patients with macula-off rhegmatogenous retinal detachment who underwent vitrectomy. Their fellow eyes were analyzed as a control group. The choroidal vascularity index (CVI), ellipsoid zone/external limiting membrane integrity, central foveal thickness, and subfoveal choroidal thickness were documented and analyzed. Linear regression analyses were performed to identify factors affecting the final best-corrected visual acuity.

RESULTS

Eyes with rhegmatogenous retinal detachment showed increased CVI (68.8 ± 4.1) compared with the control group (66.1 ± 8.8, P = 0.028). Multivariate linear regression analysis revealed that patients with a poor final best-corrected visual acuity had a longer detachment duration ( P = 0.002), worse baseline best-corrected visual acuity ( P = 0.034), thinner central foveal thickness ( P = 0.005), and greater CVI ( P = 0.001) and were more likely to be tamponated with silicone oil ( P = 0.001). Choroidal vascularity index was particularly increased in eyes with poor ellipsoid zone/external limiting membrane integrity, prolonged detachment duration, thin central foveal thickness, and worse best-corrected visual acuity.

CONCLUSION

Increased CVI could indicate poor visual outcomes in patients with macula-off rhegmatogenous retinal detachment. Choroidal remodeling could be associated with the disruption of the ellipsoid zone/external limiting membrane integrity.

Influence of Genetic Polymorphisms on the Short-Term Response to Ranibizumab in Patients With Neovascular Age-Related Macular Degeneration

Purpose

To determine whether genetic risk single nucleotide polymorphisms (SNPs) for age-related macular degeneration (AMD) influence short-term response to intravitreal ranibizumab treatment.

Methods

Forty-four treatment-naive AMD patients were included in a prospective observational study. They underwent three monthly injections of intravitreal ranibizumab for neovascular AMD. After an initial clinical examination (baseline measurement), a follow-up visit was performed to determine treatment response one month after the third injection (treatment evaluation). Patients were evaluated based on ophthalmoscopy, fluorescein angiography, optical coherence tomography (OCT), and OCT angiography. Peripheral venous blood was collected for DNA analysis at baseline visit. Patients were genotyped for single-nucleotide polymorphisms within AMD-relevant genes and classified on good or poor responders based on visual acuity, central retinal thickness, intraretinal fluid, and subretinal fluid.

Results

One hundred ten AMD-associated SNPs have been analyzed. Six were found to be relevant when associated to ranibizumab treatment response. The genetic variants rs890293 (CYP2J2), rs11200638 (HTRA1), rs405509 (APOE), rs9513070 (FLT1), and rs8135665 (SLC16A8) predisposed patients to a good response, whereas rs3093077 (CRP) was associated with a poor response. FTL1, SLC16A8, and APOE were the SNPs that showed significance (P < 0.05) but did not pass Bonferroni correction.

Conclusions

This is the first study that links novel polymorphisms in genes such as CRP, SCL16A8, or CYP2J2 to treatment response to ranibizumab therapy. On the other hand, HTRA1, FLT1, and APOE are linked to a good ranibizumab response. These SNPs may be good candidates for short-term treatment response biomarkers in AMD patients. However, further studies will be necessary to confirm our findings.

The effect of Nd:YAG Laser applied in the posterior capsule opacification on retinal and choroidal structures

PURPOSE

To assess the effect of neodymium:yttrium-aluminum-garnet (Nd-YAG) laser procedure on the choroid and retina in patients who developed posterior capsular opacification (PCO) after cataract surgery.

METHODS

In this study, 32 eyes of 30 patients who underwent Nd:YAG laser treatment for PCO were evaluated. Visual acuity (VA), intraocular pressure (IOP), central macular thickness (CMT) with optical coherence tomography device (OCT), ganglion cell layer (GCL), inner plexiform layer (IPL), retinal nerve fiber layer (RNFL) and subfoveal choroidal thickness (SCT) were measured. Choroidal vascular index (CVI) was calculated from HD line images obtained by spectral domain OCT with the software Image J.

RESULTS

The mean age of the patients participating in the study was 60.1 ± 8.9 years. There was no significant difference in IOP, CMT, RNFL, GCL, IPL and SCT values ​​in all comparisons before and after laser (p>0.05 for all values). While Nd:YAG laser pretreatment CVI was 63.2 ± 3.2%, it was 66.8 ± 2.9% at 1 week and 67.1 ± 2.6% at 1 month after laser treatment. A significant difference was detected in the comparison of pre-laser CVI and post-laser 1 week and 1 month CVI (p<0.05 for all values).

DISCUSSION

CVI was found to be significantly higher in the post-laser period in patients who underwent Nd:YAG laser. As far as the author knows, this study is the first research in the literature to evaluate this relationship. CVI can be used to evaluate choroidal vascular changes after Nd:YAG laser.

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.

Investigation of changes in retinal vascular parameters and choroidal vascular index values during the early recovery period of COVID-19: The COVID-OCTA study

BACKGROUND

COVID-19 effects microvasculature in many tissues. This study investigated whether the choroidal structure is also affected.

METHODS

This cross-sectional study included 80 patients with COVID-19 and the same number of age- and gender-matched healthy individuals. All participants' right eye measurements were examined. Optical coherence tomography angiography (OCTA) was used for imaging. Otherwise, two independent researchers used the Choroidal vascular index (CVI) for choroidal parameters calculation.

RESULTS

Superior and deep flow values were lower in the COVID-19 group than in the control group, and vascular density (VD) values were lower in all regions in this group. Except for the superior mean VD, there was no statistically significant difference (p = 0.003). However, the COVID-19 group had significantly lower subfoveal choroidal thickness (SFChT) measurements than the control group (p = 0.001). In addition, no significant difference was observed between the groups in evaluating mean CVI values (p>0.05).

CONCLUSION

Noninvasive diagnostic tools such as OCTA and EDI-OCT can be used to monitor early changes in diseases affecting microvessels, such as from COVID-19.

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.

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.

Choroidal vascularity index in leptochoroid: A comparative analysis between reticular pseudodrusen and high myopia

PURPOSE

To investigate the choroidal vascularity index (CVI) in patients affected by leptochoroid.

METHODS

Three distinct age-matched cohorts were collected: patients with reticular pseudodrusen (RPD) secondary to age-related macular degeneration, patients with high-myopia, and healthy controls. CVI was calculated in the subfoveal 6000 μm diameter area.

RESULTS

54 eyes (54 patients) were included (18 eyes in each cohort). No statistical differences were disclosed in terms of age between controls, RPD patients (p = 0.062), and myopic patients (p = 0.070). Total choroidal area showed a different distribution among the 3 cohorts (p < 0.001), due to the reduction of luminal and stromal choroidal area in both RPD and myopic groups in comparison to controls (p < 0.001). Interestingly, CVI showed a different distribution between the 3 cohorts (p < 0.001). In detail, RPD group showed no changes in CVI in comparison to controls (p = 1.000), whereas the myopic group showed a higher CVI in comparison to both RPD group and controls (p < 0.001 in both analyses).

CONCLUSIONS

Different changes of the choroidal vascular and stromal components characterize the leptochoroid secondary to RPD eyes and high-myopic eyes. The relative greater impairment of the vascular area in RPD eyes in comparison to myopic eyes could be at the basis of the lower development of RPD in patients with high myopia.

Choroidal Vascular Impairment in Intermediate Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a multifactorial disease, whose complete pathogenesis is still unclear. Local hemodynamics may play a crucial role in its manifestation and progression. To evaluate choroidal and retinal vascular parameters, a total of 134 eyes were analyzed, 100 with intermediate AMD and 34 age matched healthy controls. 131 eyes of 104 patients were eligible for complete image assessment and 3 eyes were excluded for insufficient image quality: Group 1: intermediate AMD (n = 97) and Group 2: healthy controls (n = 34). Spectral domain optic coherence tomography (SD-OCT) with enhanced depth imaging (EDI) and optic coherence tomography angiography (OCT-A) were acquired using Spectralis (Heidelberg Engineering). Choroid and retinal capillary plexus were evaluated and image binarization was used to obtain quantitative data. Mean age was 77.67 years old (YO) and 67.2% were women. Total subfoveal choroidal area and luminal area were significantly reduced in Group 1 compared with Group 2 (0.88 mm2 and 0.40 mm2 vs. 1.24 mm2 and 0.55 mm2, respectively) (p < 0.05). Regarding choriocapillary flow density, AMD eyes recorded reduced values (34.83%) compared with controls (36.25%) (p < 0.05). Chorioretinal vasculature is impaired in intermediate AMD patients and vascular parameters could be attractive new prognostic biomarkers. Future therapeutic approaches may target this vascular dysfunction and delay disease progression.

CVIS: Automated OCT-scan-based software application for the measurements of choroidal vascularity index and choroidal thickness

PURPOSE

To develop an automated image recognition software for the objective quantification of choroidal vascularity index (CVI) and choroidal thickness (CT) at different choroidal locations on images obtained from enhanced depth imaging optical coherence tomography (EDI-OCT), and to validate its reliability and investigate the difference and correlation between measurements made by manual and software.

METHODS

A total of 390 EDI-OCT scans, captured from 130 eligible emmetropic or myopic subjects, were categorized into four grades in terms of their accessibility to identify the choroidal-scleral interface (CSI) and were further assessed for CT and CVI at five locations (subfoveal, nasal, temporal, superior and inferior) by the newly developed Choroidal Vascularity Index Software (CVIS) and three ophthalmologists. Choroidal parameters acquired from CVIS were evaluated for its reliability and correlation with ocular factors, in comparison to manual measurements. Distribution of difference and correlation coefficient between CVIS and manual measurements were also analysed.

RESULTS

Choroidal Vascularity Index Software (CVIS) demonstrated excellent intra-session reliability for CT (ICC: 0.992) and CVI (ICC: 0.978) measurements, compared to the relatively lower intra- and inter-observer reliability of manual measurements. Choroidal Vascularity Index Software (CVIS) and manual assessments had the highest correlation at nasal choroid (CT: r = 0.829, p < 0.001; CVI: r = 0.665, p < 0.001). Choroidal parameters identified with CVIS showed stronger correlations with axial length than manual measurements.

CONCLUSION

This automated software, CVIS, exhibited excellent reliability compared to manual measurements, which are subject to image quality and clinical experience. With its validated clinical relevance, CVIS holds promise to serve as a flexible and robust tool in future vitreoretinal and chorioretinal studies.

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.

Longitudinal Alterations of Retinal and Choroidal Structure in Patients Recovered from COVID-19

Objective

To evaluate the midterm longitudinal changes in chorioretinal structures in patients with coronavirus disease 2019 (COVID-19).

Methods

Thirty-four eyes of 17 COVID-19 patients were enrolled. The patients underwent retinal and choroidal imaging upon the recovery (baseline) after 1 and 3 months. Retinal measurements in fovea, parafovea, and perifovea were recorded. To calculate choroidal vascularity index (CVI), luminal and total choroidal areas were measured using Sonada's method. Choroidal thickness was measured at the subfovea 500 microns temporal and nasal to the fovea.

Results

Mean CVI was 0.64 ± 0.04 at baseline that significantly increased to 0.67 ± 0.05 (P = 0.012) after 1 month and again significantly decreased to 0.63 ± 0.05 after 3 months (P < 0.001). While the stromal component showed a significant decrease between the baseline and first-month values (1.16 ± 0.29 to 1.01 ± 0.27, P = 0.03), the luminal area mostly changed between months 1 and 3 (2.03 ± 0.28 to 1.91 ± 0.23, P = 0.045). The average of subfoveal choroidal thickness and retinal thickness remained unchanged.

Conclusion

CVI is increased in patients with COVID-19 1 month after recovery from COVID-19 and returns to baseline values after 3 months. Regarding the reversible nature of changes, there might be a prominent role in inflammation.

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.

Novel volumetric imaging biomarkers for assessing disease activity in eyes with PCV

The aim of this study was to evaluate influence of baseline imaging features on visual and anatomical outcomes in eyes with PCV treated with anti-VEGF monotherapy. In this prospective study we enrolled participants with treatment-naïve PCV who followed a treat-and-extend protocol using intravitreal aflibercept (IVA) monotherapy. Baseline clinical features evaluatedincluded best corrected visual acuity (BCVA), traditional features such as lesion size, fluid-related OCT parameters and novel parameters using automated software. This included quantitative and qualitative pigment epithelium detachment (PED) parameters [height, volume]; and choroidal parameters. [choroidal thickness (CT), choroidal volume (CV) and choroidal vascularity index (CVI). We evaluated the predictive value of each parameter on visual and anatomical outcome at month 12. We additionally evaluated initial treatment response after 3 monthly injections with respect to month 12 outcomes. Fifty-two eyes from 52 participants were included in the study. The BCVA increased from 61.1 ± 13.2 to 69.6 ± 13.2 early treatment diabetic retinopathy study (ETDRS) letters (p < 0.01) and CRT reduced from 455.7 ± 182.4 µm to 272.7 ± 86.2 (p < 0.01) from baseline to month 12. The proportion of eyes with PED decreased significant from 100% at baseline to 80% at month 12 (p < 0.01). Reduction in the mean maximum height of PED (from 381.3 ± 236.3 µm to 206.8 vs ± 146.4 µm) and PED volume (from 1322 ± 853 nl to 686 ± 593 nl) (p < 0.01) was also noted from baseline to month12. Baseline features associated with better month 12 BCVA included baseline BCVA (β =  − 0.98, 95%CI − 3.38 to − 1.61, p = 0.02) and baseline CRT (β =  − 0.98, 95%CI − 1.56 to − 0.40, p = 0.04) while the disease activity at month12 was significantly associated with lower baseline CRT (366.0 ± 129.5 vs 612.0 ± 188.0 , p < 0.001), lower baseline PED height (242.0 ± 150.0 vs 542.0 ± 298.0 µm, p < 0.01), lower baseline PED volume (0.6 ± 0.3 mm³ vs 2.2 ± 1.3 mm³ vs, p < 0.01), lower proportion with marked CVH (17.9% vs 46.2%, p = 0.02) and lower mean CVI (61.8 ± 1.4 vs 63.0 ± 1.4, p < 0.02). Additionally, a larger decrease in CRT (per 100 nm) and larger PED volume reduction (per 100 nl) at month 3 from baseline were associated with greater BCVA gain and inactive disease. PED-related volumetric parameters have an additional predictive value to traditional biomarkers of disease activity in eyes with PCV undergoing anti-VEGF monotherapy. With increasingly precise quantification, PEDs can be a crucial biomarker in addition to traditional parameters and may aid in retreatment decisions.

Choroidal changes and associations with visual acuity in diabetic patients

Background

The variable visual function observed in diabetic retinopathy (DR) patients is not fully explained by the classic staging system. Our purpose was to evaluate choroidal changes, in standardized sectors, in DR patients and to find associations between choroidal measurements and visual function.

Methods

Cross-sectional study that included the right eye of diabetic patients (n = 265) without active edema, ischemia or neovascularization and age-matched controls (n = 73). Optical coherence tomography (OCT) imaging was performed with enhanced depth imaging protocol. Choroidal vascularity index (CVI) was calculated in a 5 mm scan centered in the fovea.

Results

CVI decreased with age (p < 0.001) but was not influenced by axial length. A multivariate analysis adjusting for age confirmed a significant difference in CVI between DR eyes that had previous treatments (intravitreal injections and/or photocoagulation) compared to control eyes (p = 0.013) and to DR eyes that never required treatment (p = 0.002). There was no significant difference between non-DR diabetic patients and normal controls. Considering the group of DR patients that had previous treatments, in eyes without optic media opacification, BCVA correlated with CVI (r = − 0.362, p < 0.001), whereas full retina thickness and individual retinal layer thickness did not (p > 0.066).

Conclusions

A reduction in CVI was observed in patients with a more advanced stage of DR. In treated DR patients with stable disease, choroidal biomarkers correlated with best-corrected visual acuity whereas retinal biomarkers did not.

Trial registration: N/A

Supplementary Information

The online version contains supplementary material available at 10.1186/s40942-021-00355-z.

Choroidal vascularity index in thyroid eye disease: comparison with controls and application in diagnosing non-inflammatory active disease

PURPOSE

To report the differences in choroidal vascularity index (CVI) in thyroid eye disease (TED) and normals and its discriminatory value for differentiating various stages of TED.

METHODS

Prospective, cross-sectional, non-interventional imaging study. Ninety-four eyes of 54 patients were included and divided into 5 groups - normal controls (C), inactive TED (I), active TED (A), non-inflammatory active TED (NIA) and systemic hyperthyroid disorder but no TED (SYS). Choroidal images were acquired using the swept-source optical coherence tomography and the choroid was binarized to calculate the CVI.

RESULTS

Ninety-four eyes were included. Mean age was 44.52 ± 10.02 years (median 46 years, range 19-65 years). Mean IOP was 16.1 ± 3.37 mm Hg (median 16 mm Hg, range 16-24 mm Hg). Mean Spherical equivalent (SE) was -0.08 ± 1.86 diopters (median 0, range -2.5 to +2.25). Intra-rater agreement was 0.84 (p < 0.001). Inter-rater agreement was noted to be 0.85 (p < 0.001) for consistency and 0.77 (p < 0.001) for absolute agreement. CVI in the A group was 70.11 ± 3.38% and in the NIA group was 69.32 ± 3.5%. Both were comparable to each other and significantly higher than the C, I and SYS groups (p < 0.001). Multiple regression showed that the Clinical Activity Score (CAS) had a positive effect and spheroequivalent had a negative effect on the CVI. At CVI of 66.83%, active TED can be diagnosed with sensitivity of 91.67% and specificity of 82.14%                 .

CONCLUSIONS

CVI is significantly higher in active TED and NIA TED compared to other groups. It has a good value in differentiating the non-inflammatory active TED eyes from the inactive eyes.

Assessment of choroidal vascularity and choriocapillaris blood perfusion in Chinese preschool-age anisometropic hyperopic amblyopia children

PURPOSE

To determine the macular and peripapillary area choroid microstructure parameters of hyperopic anisometropic amblyopia eyes and compare to fellow and age-matched control eyes. To assess the correlation between the axial length (AL), choroidal thickness (CT) and choroid microstructure parameters.

METHODS

This cross-sectional comparative, non-interventional study involved 52 hyperopic anisometropic amblyopia children and 48 age-matched heathy controls. 52 eyes with hyperopic anisometropic amblyopia and 48 age-matched control eyes were studied. The peripapillary and subfoveal CT were determined. The total choroidal area (TCA), luminal area (LA), and stromal area (SA) of the subfoveal and peripapillary choroid were measured. In addition, the correlation between the AL, CT and choroid microstructure parameters were calculated.

RESULTS

The peripapillary and subfoveal CT of the amblyopic eyes was significantly thicker than the fellow and control eyes (all P < 0.05). The subfoveal and peripapillary choroidal SA, LA and TCA of the amblyopic eyes were significantly increased than that of the fellow and control eyes (all P < 0.05). The choroidal vascularity index (CVI) values of the amblyopic eye were significantly different among the three groups (P < 0.05). There was a statistically significant negative correlation between AL and subfoveal CT (SFCT), LA and TCA levels (P < 0.001, P = 0.039, P = 0.027, respectively). Spherical equivalent (SE) was positive correlated with SFCT, LA and TCA levels (P = 0.456, 0.229 and 0.240, respectively; all P < 0.05). There was a statistically significant positive correlation between SFCT, SE, LA, SA, TCA and CVI levels (all P < 0.05).

CONCLUSION

The subfoveal and peripapillary CT of amblyopic children abnormally increased and correlated with shorter AL and higher SE. The choroidal structure of the amblyopic eyes was different from the fellow and control eyes, the hyperopic anisometropic amblyopic eyes had significantly thicker sub-foveal choroid, higher LA, SA, and TCA. AL and CT affect choroidal structure and vascular density. Choroidal blood flow may be increased in amblyopic eyes. The larger LA, SA, TCA, and lower CVI were characteristic of the amblyopic eye.

Choroidal caverns in pachychoroid neovasculopathy

Background. Choroid plays an important role in the pathogenesis of retinal pathology. Choroidal cavern, a recently identifi ed fi nding of optical coherent tomography (OCT), has been described in some degenerative and atrophic forms of retinal pathology. In the literature, there are only a few studies of choroidal cavers in pachychoroid neovasculopathy, newly described form of age related macular degeneration.The aim: to perform a detailed analysis of choroidal structure on OCT scans of patients with pachychoroid neovasculopathy and to reveal the frequency of choroidal caverns identifi cation.Material and methods. The data of 30 patients (30 eyes) aged 64.4 ± 5.6 years with pachychoroid neovascularization were retrospectively analyzed. The patients underwent spectral OCT and OCT-angiography (OCTA) using a Spectralis device (Heidelberg Engineering, Germany). The protocol was “Posterior Pole”, consisting of 61 scans. To assess the structure of the choroid, an enhanced image depth (EDI) module was used. OCT angiography was performed with a scan area of 6 × 6 mm. These methods were compared to identify choroidal caverns.Results. On OCT subretinal type 1 neovascularization was revealed as a fl at detachment of the pigment epithelium and visualization of blood flow on OCTA in the lesion as angled vessels (21 eyes) or a seafan (9 eyes). On OCT-EDI scans, there was diffuse or local choroidal thickening of choroid with an increase in the vessels of the Haller’s layer and thinning of the choriocapillaries. Choroidal caverns appeared on OCT and en-face OCT as areas with low optical density, round or irregular, located in different layers of the chorioid, without hyperrefl ective boundaries. A typical sign of choroidal cavern is the tail of hypertransmission after the cavern toward the sclera. Choroidal caverns were found in 4 of 30 eyes (13.3 %) and were located both near the choroidal neovascularization lesion and beyond this area.Conclusion. The prevalence of choroidal cavities, a new choroidal biomarker, in pachychoroid neovasculopathy was 13.3 %. Identification of these changes is possible with the use of modern diagnostic techniques (OCT-EDI, OCTA and en-face OCT) that allow visualization the state of the choroid. The prognostic signifi cance of choroidal cavities requires further study.

Choroidal vascularity index changes during the Valsalva manoeuvre in healthy volunteers

PURPOSE

To evaluate the effects of the Valsalva manoeuvre (VM) on the choroidal vascularity index (CVI) in healthy volunteers.

METHODS

This prospective, cross-sectional study included 60 eyes of 30 healthy volunteers. Enhanced depth imaging-optical coherence tomography scans of both eyes involving the fovea were taken, and a 1500 μm subfoveal choroidal area was selected for image binarization with open-access Fiji software. The binarized image was segmented into the stromal area (SA) and luminal area (LA), and CVI was calculated as the ratio (%) of LA to the total choroidal area (TCA). CVI, subfoveal choroidal thickness (SFCT), IOP, systolic and diastolic blood pressure were evaluated at rest and during the VM.

RESULTS

During the VM, a mean ± standard deviation increase in LA (0.02 ± 0.05 mm² , p < 0.001) and CVI (1.72 ± 2.83%, p < 0.001) was observed, whereas SA (-0.02 ± 0.05 mm² , p < 0.001) decreased. There was no significant change in TCA (0.00 ± 0.03 mm² , p = 0.55) or SFCT (1.05 ± 10.92 μm, p = 0.46). There was a moderate positive correlation between the spherical equivalent refractive error (SE) and SFCT both at rest and during VM (r₅₈  = 0.49, p < 0.0005 and r₅₈  = 0.49, p < 0.0005, respectively). However, there was no significant correlation between SE and CVI either at rest or during VM (p = 0.11 and 0.06, respectively). In a multiple linear regression analysis, CVI was only associated with SFCT; however, SFCT was also associated with SE, both at rest and during VM (p < 0.001).

CONCLUSION

Valsalva manoeuvre increases CVI by choroidal vascular dilation as demonstrated by an increase in LA and a decrease in SA. Researchers should be careful about unintentional VM during examinations.

Factors effecting the choroidal vascularity index in children with mild to moderate myopia

PURPOSE

To measure the choroidal structural parameters in a population of myopic children and determine the factors effecting the choroidal vascularity index (CVI).

METHODS

In total, 200 eyes of 200 children (100 females, 100 males) with a mean age of 11.5 ± 1.6 years were included in the study. Macular imaging was performed using EDI mode of spectral domain-optical coherence tomography. Binarization of the choroidal area was performed with ImageJ software. Total choroidal area, luminal area (LA), stromal area (SA), and CVI were automatically calculated.

RESULTS

The mean choroidal, stromal and luminal areas were measured as 0.952 ± 0.127 mm², 0.626 ± 0.103 mm² and 0.325 ± 0.076 mm², respectively. The mean CVI was 65.81% ± 6.56. Age and the axial length (AL) of the participants were not found to be associated with the LA and the CVI. (r=-0.078, p=0.274, r=0.017, p=0.808, and r=0,051, p=0.474 and r=-0.128, p=0.071, respectively). There was a statistically significant strong association between the LA and CVI measurements and SE of the participants (r=0.736, p=0.001, and r=-0.605; p=0.001).

CONCLUSION

Age and AL were not associated with the CVI, but SE was significantly associated with the CVI.

Recurrence and visual prognostic factors of polypoidal choroidal vasculopathy: 5-year results

This retrospective study aimed to evaluate the factors affecting recurrence and visual prognosis in patients with treatment-naïve subfoveal polypoidal choroidal vasculopathy (PCV). Patients who had received three consecutive intravitreal injections of ranibizumab or aflibercept and had reached remission were enrolled. They were divided into a group without recurrence (group 1, 26 eyes) and a group with recurrence (group 2, 121 eyes) and followed up for at least 5 years. Patients in group 2 received additional treatment for worsening. Logistic regression analysis revealed that a young age of onset (P = 0.001), high choroidal vascularity index (CVI; P = 0.019), and presence of choroidal vascular hyperpermeability (CVH; P = 0.037) were associated with a low risk of recurrence. Multiple regression analysis revealed that recurrence (P = 0.001), greatest linear dimension (P = 0.003), and polyp configuration (single or cluster; P = 0.043) were associated with final visual acuity. Patients without recurrence had a lower age of onset and higher CVI than those with recurrence, and they tended to have CVH. In addition, patients with recurrence, large lesion, and cluster polyps had worse final visual acuity than those without these factors. CVI and CVH may be used to predict recurrence of PCV.

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.

Choroidal Vascularity Index in Different Cohorts of Dry Age-Related Macular Degeneration

Purpose

The purpose of this study was to investigate the choroidal luminal and interstitial stromal alterations using choroidal vascularity index (CVI) among different cohorts of dry age-related macular degeneration (dAMD) compared to healthy subjects.

Methods

Four distinct cohorts were collected: three different cohorts of patients with dAMD (i.e. drusen, reticular pseudodrusen [RPD], and geographic atrophy [GA]) and an age-matched cohort of healthy subjects (controls). CVI (the ratio between the luminal choroidal area [LCA] and the total choroidal area [TCA]) was calculated in the subfoveal 1000 µm area.

Results

One hundred twenty eyes (from 120 patients) were included (30 eyes in each cohort). The mean age was 76.6 ± 7.1 years. No statistical differences were disclosed in terms of age, axial length, and central macular thickness among study groups. TCA showed a different distribution among the four cohorts (P = 0.003), mainly due to the LCA changes (P = 0.001). Interestingly, CVI showed a different distribution among the four cohorts (P < 0.001). RPD showed a lower CVI in comparison to controls (P = 0.040), whereas GA showed a lower CVI in comparison to drusen, RPD, and controls (P = 0.001, P = 0.046, and P < 0.001, respectively).

Conclusions

Different cohorts of dAMD are characterized by different impairments of the choroidal vascular and stromal components, reflecting different degrees of AMD severity.

Translational Relevance

CVI provides insights for better understanding the pathogenesis of AMD.

Short-term effect of angiotensin converting enzyme inhibitor on choroidal vascularity

PURPOSE

To determine the effect of angiotensin-converting enzyme (ACE) inhibitors on choroidal vascularity using the binarization method in a group of treatment-naïve hypertensive patients.

METHODS

There were 48 treatment-naive hypertensive patients who were diagnosed according to the "2013 European Society of Hypertension/European Society of Cardiology" guideline and started angiotensin-converting enzyme inhibitor perindopril (Coversyl) in the study. As a control group, 48 healthy volunteers were randomly selected among people who attended the outpatient clinic for routine ophthalmological examination. Enhanced-depth imaging optical coherence tomography (EDI-OCT) images were captured at baseline and at 1 month after treatment. Binarization of the EDI-OCT images was performed by Image-J software.  The choroidal thickness (CT), total choroidal area, luminal area, stromal area, and choroidal vascularity index (CVI) were measured.

RESULTS

There was a statistically significant increase in CT at all locations (subfoveal, nasal, and temporal) at 1 month after treatment compared with baseline (for all, p˂0.001). Choroidal structural parameters and the mean CVI were statistically significantly increased at 1 month after treatment (for all, p˂0.001). When compared, there was no statistically significant difference for the vascular parameters between the control group and the patient group at 1 month (for all, p>0.05).

CONLUSION

A statistically significant improvement was demonstrated in the choroidal vascular parameters except for the stromal area after treating with an ACE inhibitor in a group of hypertensive patients.

Choroidal vascularity index and retinal nerve fiber layer reflectivity in newly diagnosed migraine patients

PURPOSE

To evaluate the choroidal structural parameters, peripapillary retinal nerve fiber layer (RNFL) thickness, and optic density index (ODI) and their correlations in patients with migraine.

METHODS

Twenty-eight newly diagnosed migraine patients and 28 age-matched healthy controls were included in this prospective cross-sectional study. The enhanced depth-optical coherence tomography images were evaluated. The choroidal area (CA) was binarized to the luminal area (LA) and stromal area (SA) using Image J. The choroidal vascularity index (CVI), the mean peripapillary RNFL thickness, superior-inferior-nasal-temporal quadrant RNFL thicknesses, and the ODI were compared statistically.

RESULTS

The difference in the mean CVI between the patient group and controls reached a statistical significance (p=0.035). The mean RNFL thickness was significantly decreased in patients with migraine compared with the controls (p=0.040). The mean RNFL thickness in the superior, temporal, and inferior quadrants was significantly decreased in the patient group in comparison to the control subjects (p=0.030, p=0.001, and p=0.022, respectively). There were no significant differences between the migraine group and the controls for the mean ODI of RNFL (p=0.399).

CONCLUSION

The CVI and the RNFL thickness except for the nasal quadrant were significantly decreased in newly diagnosed migraine patients.

Alterations in choroidal vascular parameters following panretinal photocoagulation using enhanced-depth imaging optical coherence tomography in diabetic retinopathy

PURPOSE

To investigate the alteration of choroid in patients with very severe non-proliferative diabetic retinopathy (NPDR) or early proliferative diabetic retinopathy (PDR) following panretinal photocoagulation (PRP).

METHODS

Thirty-nine eyes of 21 patients with very severe non-proliferative diabetic retinopathy (NPDR) (19 eyes) and early proliferative diabetic retinopathy (PDR) (20 eyes) were recruited. Enhanced-depth imaging optical coherence tomography at baseline, 1, and 6 months after PRP was employed to measure choroidal parameters including total choroidal area (TCA) and choroidal vascular index (CVI).

RESULTS

In eyes with very severe NPDR, subfoveal TCA decreased non-significantly at month 1, which increased significantly at month 6 (539 ± 131µm², 502 ± 134µm², and 598 ± 168µm² at baseline and months 1 and 6, respectively; P = 0.003). Subfoveal CVI increased at month 1 and then decreased at month 6 (68.25 ± 3.05, 69.74 ± 3.62, and 67.84 ± 1.77 at baseline and months 1 and 6, respectively; P < 0.001). A reverse pattern occurred in eyes with early PDR, a non-significant increase in TCA at month 1 followed by a decrease at month 6 (497 ± 95µm², 514 ± 133µm², and 425 ± 95µm² at baseline and months 1 and 6, respectively; P = 0.011). CVI decreased at month 1 and remained relatively stable at month 6 (69.34 ± 3.11, 68.33 ± 3.41, and 68.50 ± 5.04 at baseline, and months 1 and 6, respectively; P = 0.023). Alteration of choroidal thickness was not statistically significant in both groups.

CONCLUSION

Eyes with very severe NPDR and early PDR exhibit a reverse pattern regarding choroidal indices after PRP.

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.

REPEATABILITY OF CHOROIDAL VASCULARITY INDEX MEASUREMENTS USING DIRECTIONAL OPTICAL COHERENCE TOMOGRAPHY IMAGES

PURPOSE

To investigate the repeatability of choroidal vascularity index (CVI) measurements in centered and decentered (regarding pupil entry position of the beam) directional subfoveal optical coherence tomography (OCT) scans with (CVI1) and without (CVI2) brightness adjustment.

METHODS

Thirty-two eyes of 32 healthy volunteers were included in this prospective study. First, the fovea was evaluated by a single horizontal enhanced depth imaging OCT scan in a centered direction. Then, the same subfoveal horizontal line was scanned in a decentered direction. The agreement between CVIs obtained from these centered and decentered directional OCT scans was investigated using Bland-Altman analysis and intraclass correlation coefficient.

RESULTS

Intraclass correlation coefficient between centered and decentered CVI1 was 0.71 (95% CI: 0.48-0.85, P value < 0.001). Intraclass correlation coefficient between centered and decentered CVI2 was 0.73 (95% CI: 0.5-0.86, P value < 0.001). The mean difference between centered and decentered directional measurements for CVI1 and CVI2 were 0.5 and 0.8, respectively.

CONCLUSION

There is moderate agreement between CVIs obtained from centered and decentered directional single OCT scans of the same subfoveal area. Studies investigating choroidal vascularity should be standardized by using the same OCT beam direction in all scans.

OCT Biomarkers in Neovascular Age-Related Macular Degeneration: A Narrative Review

Age-related macular degeneration (AMD) is the leading cause of legal blindness in elderly people. Neovascular AMD (nAMD) is responsible for the majority of cases of severe visual loss in eyes with AMD. Optical coherence tomography (OCT) is the most widely used technology for the diagnosis and follow-up of nAMD patients, which is widely used to study and guide the clinical approach, as well as to predict and evaluate treatment response. The aim of this review is to describe and analyze various structural OCT-based biomarkers, which have practical value during both initial assessment and treatment follow-up of nAMD patients. While central retinal thickness has been the most common and one of the first OCT identified biomarkers, today, other qualitative and quantitative biomarkers provide novel insight into disease activity and offer superior prognostic value and better guidance for tailored therapeutic management. The key importance of retinal fluid compartmentalization (intraretinal fluid, subretinal fluid, and subretinal pigment epithelium (RPE) fluid) will be discussed firstly. In the second part, the structural alterations of different retinal layers in various stages of the disease (photoreceptors layer integrity, hyperreflective dots, outer retinal tubulations, subretinal hyperreflective material, and retinal pigment epithelial tears) will be analyzed in detail. The last part of the review will focus on how alterations of the vitreoretinal interface (vitreomacular adhesion and traction) and of the choroid (sub-RPE hyperreflective columns, prechoroidal clefts, choroidal caverns, choroidal thickness and choroidal volume, and choroidal vascular index) interact with nAMD progression. OCT technology is evolving very quickly, and new retinal biomarkers are continuously described. This up-to-date review article provides a comprehensive description on how structural OCT-based biomarkers provide a valuable tool to monitor the progression of the disease and the treatment response in nAMD patients. Thus, in this perspective, clinicians will be able to allocate hospital resources in the best possible way and tailor treatment to the individual patient's needs.

Multicentre, randomised clinical trial comparing intravitreal aflibercept monotherapy versus aflibercept combined with reduced-fluence photodynamic therapy (RF-PDT) for the treatment of polypoidal choroidal vasculopathy

PURPOSE

To compare the efficacy and safety of intravitreal aflibercept (IVA) monotherapy versus aflibercept combined with reduced-fluence photodynamic therapy (RF-PDT) (IVA+RF-PDT) for the treatment of polypoidal choroidal vasculopathy (PCV).

METHODS AND ANALYSIS

Multicentred, double-masked, randomised controlled trial to compare the two treatment modalities. The primary outcome of the study is to compare the 52-week visual outcome of IVA versus IVA+RF PDT. One hundred and sixty treatment-naïve patients with macular PCV confirmed on indocyanine green angiography will be recruited from three centres in Singapore. Eligible patients will be randomised (1:1 ratio) into one of the following groups: IVA monotherapy group-aflibercept monotherapy with sham photodynamic therapy (n=80); combination group-aflibercept with RF-PDT (n=80). Following baseline visit, all patients will be monitored at 4 weekly intervals during which disease activity will be assessed based on best-corrected visual acuity (BCVA), ophthalmic examination findings, optical coherence tomography (OCT) and angiography where indicated. Eyes that meet protocol-specified retreatment criteria will receive IVA and sham/RF-PDT according to their randomisation group. Primary endpoint will be assessed as change in BCVA at week 52 from baseline. Secondary endpoints will include anatomical changes based on OCT and dye angiography as well as safety assessment. Additionally, we will be collecting optical coherence tomography angiography data prospectively for exploratory analysis.

ETHICS AND DISSEMINATION

This study will be conducted in accordance with the ethical principles that have their origin in the Declaration of Helsinki and that are consistent with the ICH E6 guidelines of Good Clinical Practice and the applicable regulatory requirements. Approval from the SingHealth Centralised Institutional Review Board has been sought prior to commencement of the study.

TRIAL REGISTRATION NUMBER

NCT03941587.

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.

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.

CHOROIDAL VASCULARITY INDEX IN YOUNG CHOROIDEREMIA PATIENTS

PURPOSE

To evaluate choroidal features in young patients affected by choroideremia (CHM).

METHODS

Young CHM patients and control subjects were recruited at the Eye Clinic in Florence. High-resolution choroidal imaging was obtained using swept-source optical coherence tomography with long optical coherence tomography scans (12 × 9 mm optical coherence tomography scans). We considered the subfoveal choroidal area within 9 mm of the optic disk in the horizontal plane and the subfoveal choroidal area within a 3-mm diameter centered over the fovea. The subfoveal choroidal thickness, total choroidal area, luminal area, stromal area, and choroidal vascularity index were assessed using the "ImageJ" software in both groups.

RESULTS

Eight patients (16 eyes; mean age, 19.3 ± 5.2 years) and seven control subjects (14 eyes; mean age, 19.0 ± 5.0 years) were included in this study. Best-corrected visual acuity was 20/20 in both eyes of seven CHM patients and in all control subjects and 20/25 in both eyes in one CHM patient. Mean subfoveal choroidal thickness did not differ between CHM patients and control subjects. Luminal area9mm, stromal area9mm, and total choroidal area9mm were reduced in patients compared with the control group. Luminal area3mm, stromal area3mm, and total choroidal area3mm did not differ between patients and control subjects. Choroidal vascularity index9mm and choroidal vascularity index3mm were not different between patients and control subjects.

CONCLUSION

There are no differences in the choroidal vascularity index between young CHM patients and control subjects; this result suggests a simultaneous, proportional impairment of both the stromal and vascular components of the choroid in the early stages of the disease.

Choroidal vascularity index in thyroid-associated ophthalmopathy: a cross-sectional study

Background

Hemodynamic changes have been observed in patients with Graves’ disease. The aim of our study was to evaluate choroidal vascular change using the choroidal vascularity index (CVI) in patients with thyroid-associated ophthalmopathy (TAO).

Methods

In this cross-sectional observational study, 40 patients affected by TAO were recruited. Forty healthy individuals, matched for age and sex, served as controls. Foveal enhanced-depth imaging optical coherence tomography scans were obtained from all participants. Images were binarized using the ImageJ software and luminal area (LA) and total choroidal area (TCA) were measured. CVI was calculated as the proportion of LA to TCA. The relation between CVI or subfoveal choroidal thickness (SFCT) and clinical activity score, exophthalmometric value, diplopia status, gender, and age was evaluated.

Results

CVI was significantly higher in patients with TAO (P = 0.004). No significant difference was observed in SFCT (P = 0.200) and TCA (P = 0.153) comparing TAO patients and healthy controls. LA was significantly higher in TAO group (P = 0.045). On multiple regression analysis, CVI was associated with TCA (P = 0.043). No association was found between SFCT or CVI and TCA, clinical activity score, exophthalmometric value, Inami value, diplopia status, gender or age (P > 0.05).

Conclusions

This is the first study that has demonstrated an increase in CVI in eyes with TAO compared with healthy controls and has assessed its association with clinical features.

Choroidal and Retinal Changes After Systemic Adrenaline and Photodynamic Therapy in Non-Human Primates

Purpose

To determine the tomographic, angiographic, and histologic changes in the choroid and retina of cynomolgus monkeys after systemic adrenaline and verteporfin photodynamic therapy (vPDT).

Methods

Six cynomolgus monkeys (12 eyes) were treated with vPDT only (n = 2), adrenaline only for eight weeks (n = 2), adrenaline for eight weeks with vPDT at week 4 (n = 4), and adrenaline for 12 weeks and vPDT at week 8 (n = 4). Spectral-domain optical coherence tomography, angiography, and autofluorescence were performed at baseline and every 14 days thereafter until 28 days after adrenaline therapy or vPDT. Choroid parameters included choroidal thickness (CT) changes and structural changes using semiautomated image binarization. Histology with light and electron microscopy was performed.

Results

Adrenaline resulted in subfoveal CT increase at week 4 compared with baseline (3.4%, P = 0.010), with further increase at week 8 (3.9%, P = 0.007). This correlated with choroidal luminal area increase (16.0% at week 8 compared with baseline, P = 0.030). Outer retinal changes included subretinal fluid, ellipsoid zone (EZ) disruption, photoreceptor elongation, and sub/intraretinal bright dots. Hypocyanescent spots surrounded by leakage was observed. Histology showed dilated choroidal vessels, intracytoplasmic vacuoles, and retinal pigment epithelium (RPE) enlarged basal infoldings. The vPDT decreased subfoveal CT at four weeks after vPDT (−7.5%, P = 0.007). This correlated with choroidal stromal area decrease (−18.0%, P < 0.010). Within the treatment spot, there was outer retinal atrophy, EZ disruption, irregular RPE thickening, intense hypoautofluorescence, hyperfluorescence, and hypocyanescence. On histology, there were outer retina, RPE, and choroid changes.

Conclusions

Adrenaline induces choroidal vessel dilation and CT increase. The vPDT decreases CT because of a reduction in choroidal stromal component.

Choroidal Structural Analysis in Alzheimer Disease, Mild Cognitive Impairment, and Cognitively Healthy Controls

PURPOSE

To assess choroidal structural parameters in symptomatic Alzheimer disease (AD), mild cognitive impairment (MCI), and cognitively healthy control subjects.

DESIGN

Prospective cross-sectional study.

METHODS

This study took place in an outpatient neurological disorders clinic. Participants included 67 patients (112 eyes) with AD, 74 patients (143 eyes) with MCI, and 137 (248 eyes) control subjects. Subjects with diabetes, glaucoma, or retinal pathology were excluded. High-definition enhanced depth imaging foveal scans were obtained using Zeiss Cirrus HD-5000 AngioPlex. Subfoveal choroidal thickness (SFCT) was measured by 2 masked graders with a third adjudicator. Total choroidal area (TCA), luminal area (LA), and the choroidal vascularity index (CVI) were calculated after image binarization. Association of choroidal parameters with AD, MCI, or control subjects was assessed using multivariable generalized estimating equations, adjusted for age, sex, and visual acuity.

RESULTS

After adjustment for age, sex, and visual acuity, TCA was significantly greater in patients with AD (ß = 2.73; p = .001) and MCI (ß = 4.38; p < .001) compared with control subjects. LA was significantly greater in patients with AD (ß = 1.68; p = .001) and MCI (ß = 2.69; p < .001) compared with control subjects, and CVI was significantly lower in patients with MCI (ß = -0.58; p = .002) compared with control subjects. SFCT was similar among patients with AD and MCI and control subjects on multivariable analysis (p > .05).

CONCLUSIONS

TCA, LA, and CVI may differ between patients with AD, MCI, and healthy cognition, whereas SFCT may not differ among these groups. TCA, LA, and CVI deserve further study in subjects on the Alzheimer continuum.

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.

Correlation between the Angiographic Choriocapillaris and the Structural Inner Choroid

Purpose: To assess the correlation between the choriocapillaris (CC) on optical coherence tomography (OCT) angiography and the inner choroid (IC) on structural OCT.Methods: In this prospective, cross-sectional, observational, pilot study, consecutive healthy subjects were imaged with a 6x6mm macular scan using OCTA PlexElite. Angiographic images of the CC were isolated using 10 μm-thick slab starting 21 μm posterior to the automatically segmented retinal pigment epithelium (RPE) band centerline. The structural en face OCT images of the IC were isolated using five 10 μm-thick slabs starting 11 to 51 μm posterior to the automatically segmented RPE band centerline. Retinal vessels masking was obtained by two methods: automated OCTA superficial vessel slab and automated structural OCT outer retina to CC (ORCC) slab. The en face OCT images were binarized for computation of the stromal index (SI). The flow deficits (FD) of the angiographic CC were correlated with the SI of the structural en face OCTs of the IC.Results: Twenty eyes of 20 subjects were enrolled. The strongest correlation was observed between the CC FD and the inner choroid SI of the 31-41 slab (IC SI_31-41) using the ORCC mask (R = 0.603, p = .005). Similar results were observed when the analysis was repeated when using IC SI_31-41 values obtained with the superficial vessels mask (R = 0.561, p = .01).Conclusions: The angiographic CC FD was significantly correlated with the structural inner choroidal stromal index. These findings suggest that there may be an opportunity to use structural OCT data to analyze the CC, which may allow longitudinal assessment from historical structural OCT datasets.