Characteristics of Neovascularization in Early Stages of Proliferative Diabetic Retinopathy by Optical Coherence Tomography Angiography

Recent advances and applications of optical coherence tomography angiography in diabetic retinopathy

Introduction

Optical coherence tomography angiography (OCTA), a noninvasive imaging technique, is increasingly used in managing ophthalmic diseases like diabetic retinopathy (DR). This review examines OCTA's imaging principles, its utility in detecting DR lesions, and its diagnostic advantages over fundus fluorescein angiography (FFA).

Methods

We systematically analyzed 75 articles (2015-2024) from the Web of Science Core Collection, focusing on OCTA's technical principles, clinical applications in DR diagnosis, and its use in diabetes mellitus (DM) without DR and prediabetes. The use of artificial intelligence (AI) in OCTA image analysis for DR severity evaluation was investigated.

Results

OCTA effectively identifies DR lesions and detects early vascular abnormalities in DM and prediabetes, surpassing FFA in noninvasiveness and resolution. AI integration enhances OCTA's capability to diagnose, evaluate, and predict DR progression.

Discussion

OCTA offers significant clinical value in early DR detection and monitoring. Its synergy with AI holds promise for refining diagnostic precision and expanding predictive applications, positioning OCTA as a transformative tool in future ophthalmic practice.

Comparison of Neovascularization Detection in Proliferative Diabetic Retinopathy Using Widefield Swept-source Optical Coherence Tomography Angiography and Fluorescein Angiography Among Ophthalmology Residents at a Single Institution

BACKGROUND AND OBJECTIVE

This study compares the ability of resident ophthalmologists to identify neovascularization (NV) in patients with proliferative diabetic retinopathy (PDR) using widefield swept-source optical coherence tomography angiography (SS-OCTA) and fluorescein angiography (FA).

PATIENTS AND METHODS

Fluorescein angiography and SS-OCTA images were scrambled to create a grading set consisting of 1) early and late phase FA images, 2) B-scan videos, and 3) vitreoretinal interface (VRI) slab. Participants were asked to identify NV.

RESULTS

Twelve resident physicians participated in the study. Resident physicians correctly identified 75.6% of NV using FA, 65.3% of NV using SS-OCTA B-scans, and 90.7% of NV using the SSOCTA VRI slab. There was no statistically significant difference in participants' ability to detect NV across imaging modalities (P = 0.08).

CONCLUSION

Detection rates of NV using SS-OCTA were comparable to that of using FA. Results suggest that SS-OCTA may be an appropriate imaging modality for detection of NV in PDR patients. [Ophthalmic Surg Lasers Imaging Retina 2025;56:160-165.].

Reassessment of arterial versus venous perfusion of diabetic retinal neovascularization using ultrawide-field fluorescein angiography

PURPOSE

The purpose of this study was to assess whether diabetic NV is perfused by the arterial or the venous circulation.

METHODS

This is a retrospective, consecutive case series evaluating patients with proliferative diabetic retinopathy (PDR) imaged with ultrawide-field (UWF) fluorescein angiography (FA). Areas of neovascularization elsewhere (NVE) and neovascularization of the disc (NVD) were assessed. Perfusion was defined as arterial, arteriovenous, or venous if the area of diabetic neovascularization (NV) began to hyperfluoresce either prior, during, or after laminar venous flow, respectively.

RESULTS

A total of 180 eyes from 176 patients with 928 NV were identified (830 NVE, 98 NVD). Of those, 5.1% of NVE were classified as arterial and 58.2% of NVD were classified as arterial. The remaining NV were classified as arteriovenous except for a small subset (6.1%) which were indeterminate. None of the NV were classified as venous. Noteworthy examples demonstrated NV that nearly fully perfused prior to any detectable fluorescence within nearby veins as well as clear shunting of blood from a feeding artery to a draining vein.

CONCLUSIONS

UWF FA images suggest that some NV is perfused by retinal arteries. This may be useful in devising strategies for early detection and treatment of NV precursors.

KEY MESSAGES

What is known • Diabetic retinal neovascularization has long been thought to be perfused by the retinal venous circulation. • Vascular endothelial growth factor has been shown to play key roles in both angiogenesis and arteriogenesis. What is new • Ultrawide-field fluorescein angiography demonstrates that at least some diabetic neovascularization is perfused by the retinal arterial circulation. • This supports the hypothesis that diabetic neovascularization may arise from arterially-perfused intraretinal microvascular abnormalities in the capillary bed.

Optical coherence tomography angiography in diabetic retinopathy: A major review

Diabetic retinopathy (DR) is characterized by retinal vasculopathy and is a leading cause of visual impairment. Optical coherence tomography angiography (OCTA) is an innovative imaging technology that can detect various pathologies and quantifiable changes in retinal microvasculature. We briefly describe its functional principles and advantages over fluorescein angiography and perform a comprehensive review on its clinical applications in the screening or management of people with prediabetes, diabetes without clinical retinopathy (NDR), nonproliferative DR (NPDR), proliferative DR (PDR), and diabetic macular edema (DME). OCTA reveals early microvascular alterations in prediabetic and NDR eyes, which may coexist with sub-clinical neuroretinal dysfunction. Its applications in NPDR include measuring ischemia, detecting retinal neovascularization, and timing of early treatment through predicting the risk of retinopathy worsening or development of DME. In PDR, OCTA helps characterize the flow within neovascular complexes and evaluate their progression or regression in response to treatment. In eyes with DME, OCTA perfusion parameters may be of predictive value regarding the visual and anatomical gains associated with treatment. We further discussed the limitations of OCTA and the benefits of its incorporation into an updated DR severity scale.

Longitudinal Assessment of Intraretinal Microvascular Abnormalities in Diabetic Retinopathy Using Swept-Source Optical Coherence Tomography Angiography

Purpose

To longitudinally investigate the changes in intraretinal microvascular abnormalities (IRMAs) over time, employing swept-source optical coherence tomography angiography in eyes with diabetic retinopathy.

Methods

In this retrospective, longitudinal study, we evaluated 12 × 12-mm swept-source optical coherence tomography angiography centered on the macula at baseline and last available follow-up visit for (1) IRMA changes during follow-up, defined as (a) stable, (b) regressed, (c) obliterated, and (d) progressed; and the (2) development of new neovascularization (NV) and their origins. Competing-risk survival analysis was used to assess the factors associated with these changes.

Results

In total, 195 eyes from 131 participants with diabetic retinopathy were included. Stable, regressed, obliterated, and progressed IRMA were observed in 65.1%, 12.8%, 11.3%, and 19% of eyes with diabetic retinopathy, respectively. Anti-VEGF injections during the follow-up periods and a slower increase of foveal avascular zone were associated with IRMA regression (P < 0.001 and P = 0.039). Obliterated IRMA were correlated with previous panretinal photocoagulation (P < 0.001) and a lower deep capillary plexus vessel density at baseline (P = 0.007), as well as with follow-up anti-VEGF injections (P = 0.025). A higher baseline ischemia index (ISI) and panretinal photocoagulation during the follow-up periods were associated with IRMA progression (P = 0.049 and P < 0.001). A faster increase in ISI predicted the development of NV elsewhere (NVE) from veins (P < 0.001). No significant factors were found to be associated with NVE originating from IRMA.

Conclusions

Changes in IRMA closely correlated with the severity of retinal ischemia and treatment. Notably, our study confirmed the potential, yet relatively rare, development of NVE from IRMA in a large cohort; however, the risk factors associated with this transformation require further exploration.

Early Sign of Retinal Neovascularization Evolution in Diabetic Retinopathy: A Longitudinal OCT Angiography Study

Purpose

To assess whether the combination of en face OCT and OCT angiography (OCTA) can capture observable, but subtle, structural changes that precede clinically evident retinal neovascularization (RNV) in eyes with diabetic retinopathy (DR).

Design

Retrospective, longitudinal study.

Participants

Patients with DR that had at least 2 visits.

Methods

We obtained wide-field OCTA scans of 1 eye from each participant and generated en face OCT, en face OCTA, and cross-sectional OCTA. We identified eyes with RNV sprouts, defined as epiretinal hyperreflective materials on en face OCT with flow signals breaching the internal limiting membrane on the cross-sectional OCTA without recognizable RNV on en face OCTA and RNV fronds, defined as recognizable abnormal vascular structures on the en face OCTA. We examined the corresponding location from follow-up or previous visits for the presence or progression of the RNV.

Main Outcome Measures

The characteristics and longitudinal observation of early signs of RNV.

Results

From 71 eyes, we identified RNV in 20 eyes with the combination of OCT and OCTA, of which 13 (65%) were photographically graded as proliferative DR, 6 (30%) severe nonproliferative DR, and 1 (5%) moderate nonproliferative diabetic retinopathy. From these eyes, we identified 38 RNV sprouts and 26 RNV fronds at the baseline. Thirty-four RNVs (53%) originated from veins, 24 (38%) were from intraretinal microabnormalities, and 6 (9%) were from a nondilated capillary bed. At the final visit, 53 RNV sprouts and 30 RNV fronds were detected. Ten eyes (50%) showed progression, defined as having a new RNV lesion or the development of an RNV frond from an RNV sprout. Four (11%) RNV sprouts developed into RNV fronds with a mean interval of 7.0 months. Nineteen new RNV sprouts developed during the follow-up, whereas no new RNV frond was observed outside an identified RNV sprout. The eyes with progression were of younger age (P = 0.014) and tended to be treatment naive (P = 0.07) compared with eyes without progression.

Conclusions

Longitudinal observation demonstrated that a combination of en face OCT and cross-sectional OCTA can identify an earlier form of RNV before it can be recognized on en face OCTA.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Comparison of Widefield OCT Angiography Features Between Severe Non-Proliferative and Proliferative Diabetic Retinopathy

INTRODUCTION

There is a high and ever-increasing global prevalence of diabetic retinopathy (DR) and invasive imaging techniques are often required to confirm the presence of proliferative disease. The aim of this study was to explore the images of a rapid and non-invasive technique, widefield optical coherence tomography angiography (OCT-A), to study differences between patients with severe non-proliferative and proliferative DR (PDR).

METHODS

We conducted an observational longitudinal study from November 2022 to March 2023. We recruited 75 patients who were classified into a proliferative group (28 patients) and severe non-proliferative group (47 patients). Classification was done by specialist clinicians who had full access to any multimodal imaging they required to be confident of their diagnosis, including fluorescein angiography. For all patients, we performed single-shot 4 × 4 and 10 × 10 mm (widefield) OCT-A imaging and when possible, the multiple images required for mosaic 17.5 × 17.5 mm (ultra widefield) OCT-A imaging. We assessed the frequency with which proliferative disease was identifiable solely from these OCT-A images and used custom-built MATLAB software to analyze the images and determine computerized metrics such as density and intensity of vessels, foveal avascular zone, and ischemic areas.

RESULTS

On clinically assessing the OCT-A 10 × 10 fields, we were only able to detect new vessels in 25% of known proliferative images. Using ultra-widefield mosaic images, however, we were able to detect new vessels in 100% of PDR patients. The image analysis metrics of 4 × 4 and 10 × 10 mm images did not show any significant differences between the two clinical groups. For mosaics, however, there were significant differences in the capillary density in patients with PDR compared to severe non-PDR (9.1% ± 1.9 in the PDR group versus 11.0% ± 1.9 for severe group). We also found with mosaics a significant difference in the metrics of ischemic areas; average area of ischemic zones (253,930.1 ± 108,636 for the proliferative group versus 149,104.2 ± 55,101.8 for the severe group.

CONCLUSIONS

Our study showed a high sensitivity for detecting PDR using only ultra-widefield mosaic OCT-A imaging, compared to multimodal including fluorescein angiography imaging. It also suggests that image analysis of aspects such as ischemia levels may be useful in identifying higher risk groups as a warning sign for future conversion to neovascularization.

Optical Coherence Tomography Angiography as a Diagnostic Tool for Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus, leading to visual impairment if left untreated. This review discusses the use of optical coherence tomography angiography (OCTA) as a diagnostic tool for the early detection and management of DR. OCTA is a fast, non-invasive, non-contact test that enables the detailed visualisation of the macular microvasculature in different plexuses. OCTA offers several advantages over fundus fluorescein angiography (FFA), notably offering quantitative data. OCTA is not without limitations, including the requirement for careful interpretation of artefacts and the limited region of interest that can be captured currently. We explore how OCTA has been instrumental in detecting early microvascular changes that precede clinical signs of DR. We also discuss the application of OCTA in the diagnosis and management of various stages of DR, including non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR), diabetic macular oedema (DMO), diabetic macular ischaemia (DMI), and pre-diabetes. Finally, we discuss the future role of OCTA and how it may be used to enhance the clinical outcomes of DR.

A pilot optical coherence tomography angiography classification of retinal neovascularization in retinopathy of prematurity

Extraretinal neovascularization is a hallmark of treatment-requiring retinopathy of prematurity (ROP). Optical coherence tomography angiography (OCTA) offers vascular flow and depth information not available from indirect ophthalmoscopy and structural OCT, but OCTA is only commercially available as a tabletop device. In this study, we used an investigational handheld OCTA device to study the vascular flow in and around retinal neovascularization in seven preterm infants with treatment-requiring ROP and contrasted them to images of vascular flow in six infants of similar age without neovascular ROP. We showed stages of retinal neovascularization visible in preterm infants from 32 to 47 weeks postmenstrual age: Intraretinal neovascularization did not break through the internal limiting membrane; Subclinical neovascular buds arose from retinal vasculature with active flow through the internal limiting membrane; Flat neovascularization in aggressive ROP assumed a low-lying configuration compared to elevated extraretinal neovascular plaques; Regressed neovascularization following treatment exhibited decreased vascular flow within the preretinal tissue, but flow persisted in segments of retinal vessels elevated from their original intraretinal location. These findings enable a pilot classification of retinal neovascularization in eyes with ROP using OCTA, and may be helpful in detailed monitoring of disease progression, treatment response and predicting reactivation.

A Complete Review of Automatic Detection, Segmentation, and Quantification of Neovascularization in Optical Coherence Tomography Angiography Images

Optical coherence tomography (OCT) is revolutionizing the way we assess eye complications such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). With its ability to provide layer-by-layer information on the retina, OCT enables the early detection of abnormalities emerging underneath the retinal surface. The latest advancement in this field, OCT angiography (OCTA), takes this to the next level by providing detailed vascular information without requiring dye injections. One of the most significant indicators of DR and AMD is neovascularization, the abnormal growth of unhealthy vessels. In this work, the techniques and algorithms used for the automatic detection, classification, and segmentation of neovascularization in OCTA images are explored. From image processing to machine learning and deep learning, works related to automated image analysis of neovascularization are summarized from different points of view. The problems and future work of each method are also discussed.

Comparison of widefield swept-source optical coherence tomographic angiography and fluorescein fundus angiography for detection of retinal neovascularization with diabetic retinopathy

BACKGROUND

To compare vitreous angiomosaic images (VAMIs), obtained by widefield swept-source optical coherence tomographic angiography (wfSS-OCTA) and the image of fluorescein fundus angiography (FFA) in the identification of retinal neovascularization (NV) in patients with diabetic retinopathy (DR).

METHODS

In this prospective observational study, severe non-proliferative diabetic retinopathy (NPDR) or proliferative DR (PDR) patients were included. All patients underwent FFA and wfSS-OCTA. The number of NVs identified by wfSS-OCTA VAMIs using five fixations 12 × 12 mm montage scans and the resembling FFA images were compared.

RESULTS

Fifty-three eyes of 29 patients were enrolled. NVs were detected in 25 eyes by using FFA, including 9 NVs of the disc (NVDs) and 72 NVs elsewhere (NVEs), and in 29 eyes by OCTA, including 11 NVDs and 90 NVEs. The detection rate of NV and NVD of OCTA was comparable to that of FFA (p > 0.05), and the level of agreement was excellent (κ = 0.850, κ = 0.754). Using FFA as the gold standard, the sensitivity for detection of NV by OCTA was 100.0%, specificity was 85.7%, the positive-predictive value was 86.2%, and the negative-predictive value was 100.0%. Compared with FFA, OCTA was superior in terms of the number of NVEs identified (p = 0.024). When we excluded images of patients treated with anti-vascular endothelial growth factor (VEGF) intravitreal therapy for < 3 months, OCTA was comparable to FFA in terms of the number of NVEs discovered (p = 0.203), with excellent agreement (intraclass correlation coefficient = 0.941).

CONCLUSIONS

WfSS-OCTA is an independent non-invasive alternative to FFA for NV discovery, NVD detection, and individual NVE identification, particularly in patients with PDR who have a history of prior treatment with anti-VEGF.

Inter-Rater Reliability of Proliferative Diabetic Retinopathy Assessment on Wide-Field OCT-Angiography and Fluorescein Angiography

Purpose

To assess inter-rater reliability in the detection of proliferative diabetic retinopathy (PDR) changes using wide-field optical coherence tomography angiography (WF-OCTA) versus fluorescein angiography (FA).

Methods

This retrospective, cross-sectional study included patients with severe nonproliferative and PDR. Images were acquired with 12 × 12 mm WF-OCTA and FA with a 55° lens. Images were cropped to represent the exact same field of view. Qualitative (detection of neovascularization at the disc [NVD] and elsewhere [NVE], enlarged foveal avascular zone [FAZ], vitreous hemorrhage [VH]) and quantitative analyses (FAZ area, horizontal, vertical, and maximum FAZ diameter) were performed by 2 masked graders using ImageJ. Inter-rater reliability was calculated using unweighted Cohen's kappa coefficient (κ) for qualitative analyses and intraclass correlation coefficients (ICC) for quantitative analyses.

Results

Twenty-three eyes of 17 patients were included. Inter-rater reliability was higher for FA than for WF-OCTA in qualitative analyses: κ values were 0.65 and 0.78 for detection of extended FAZ, 0.83 and 1.0 for NVD, 0.78 and 1.0 for NVE, and 0.19 and 1 for VH for WF-OCTA and FA, respectively. In contrast, inter-rater reliability was higher for WF-OCTA than for FA in the quantitative analyses: ICC values were 0.94 and 0.76 for FAZ size, 0.92 and 0.79 for horizontal FAZ diameter, 0.82 and 0.72 for vertical FAZ diameter, and 0.88 and 0.82 for maximum FAZ diameter on WF-OCTA and FA, respectively.

Conclusions

Inter-rater reliability of FA is superior to WF-OCTA for qualitative analyses whereas inter-rater reliability of WF-OCTA is superior to FA for quantitative analyses.

Translational Relevance

The study highlights the specific merits of both imaging modalities in terms of reliability. FA should be preferred for qualitative parameters, whereas WF-OCTA should be preferred for quantitative parameters.

Optical coherence tomography angiography: a review of the current literature

This narrative review presents a comprehensive examination of optical coherence tomography angiography (OCTA), a non-invasive retinal vascular imaging technology, as reported in the existing literature. Building on the coherence tomography principles of standard OCT, OCTA further delineates the retinal vascular system, thus offering an advanced alternative to conventional dye-based imaging. OCTA provides high-resolution visualisation of both the superficial and deep capillary networks, an achievement previously unattainable. However, image quality may be compromised by factors such as motion artefacts or media opacities, potentially limiting the utility of OCTA in certain patient cohorts. Despite these limitations, OCTA has various potential clinical applications in managing retinal and choroidal vascular diseases. Still, given its considerable cost implications relative to current modalities, further research is warranted to justify its broader application in clinical practice.

Optical Coherence Tomography Angiography in Retinal Vascular Disorders

Traditionally, abnormalities of the retinal vasculature and perfusion in retinal vascular disorders, such as diabetic retinopathy and retinal vascular occlusions, have been visualized with dye-based fluorescein angiography (FA). Optical coherence tomography angiography (OCTA) is a newer, alternative modality for imaging the retinal vasculature, which has some advantages over FA, such as its dye-free, non-invasive nature, and depth resolution. The depth resolution of OCTA allows for characterization of the retinal microvasculature in distinct anatomic layers, and commercial OCTA platforms also provide automated quantitative vascular and perfusion metrics. Quantitative and qualitative OCTA analysis in various retinal vascular disorders has facilitated the detection of pre-clinical vascular changes, greater understanding of known clinical signs, and the development of imaging biomarkers to prognosticate and guide treatment. With further technological improvements, such as a greater field of view and better image quality processing algorithms, it is likely that OCTA will play an integral role in the study and management of retinal vascular disorders. Artificial intelligence methods-in particular, deep learning-show promise in refining the insights to be gained from the use of OCTA in retinal vascular disorders. This review aims to summarize the current literature on this imaging modality in relation to common retinal vascular disorders.

Optical Coherence Tomography Angiography of Volumetric Arteriovenous Relationships in the Healthy Macula and Their Derangement in Disease

Purpose

To characterize relative arteriovenous connectivity of the healthy macula imaged by optical coherence tomography angiography (OCTA) using a new volumetric tool.

Methods

OCTA volumes were obtained for 20 healthy controls (20 eyes). Two graders identified superficial arterioles and venules. We implemented a custom watershed algorithm to identify capillaries most closely connected to arterioles and venules by using the large vessels as seeds to flood the vascular network. We calculated ratios of arteriolar- to venular-connected capillaries (A/V ratios) and adjusted flow indices (AFIs) for superficial capillary plexuses (SCPs), middle capillary plexuses (MCPs), and deep capillary plexuses (DCPs). We also analyzed two eyes with proliferative diabetic retinopathy (PDR) and one eye with macular telangiectasia (MacTel) to evaluate the utility of this method in visualizing pathological vascular connectivity.

Results

In healthy eyes, the MCP showed a greater proportion of arteriolar-connected vessels than the SCP and DCP (all P < 0.001). In the SCP, the arteriolar-connected AFI exceeded the venular-connected AFI, but this pattern reversed in the MCP and DCP, with higher venular-connected AFI (all P < 0.001). In PDR eyes, preretinal neovascularization originated from venules, whereas intraretinal microvascular abnormalities were heterogeneous, with some originating from venules and others representing dilated MCP capillary loops. In MacTel, diving SCP venules formed the epicenter of the outer retinal anomalous vascular network.

Conclusions

Healthy eyes showed a higher MCP A/V ratio but relatively slower arteriolar vs. venular flow velocity in the MCP and DCP, which may explain deep retinal vulnerability to ischemia. In eyes with complex vascular pathology, our connectivity findings were consistent with histopathologic studies.

Deep learning-based signal-independent assessment of macular avascular area on 6×6 mm optical coherence tomography angiogram in diabetic retinopathy: a comparison to instrument-embedded software

SYNOPSIS

A deep-learning-based macular extrafoveal avascular area (EAA) on a 6×6 mm optical coherence tomography (OCT) angiogram is less dependent on the signal strength and shadow artefacts, providing better diagnostic accuracy for diabetic retinopathy (DR) severity than the commercial software measured extrafoveal vessel density (EVD).

AIMS

To compare a deep-learning-based EAA to commercial output EVD in the diagnostic accuracy of determining DR severity levels from 6×6 mm OCT angiography (OCTA) scans.

METHODS

The 6×6 mm macular OCTA scans were acquired on one eye of each participant with a spectral-domain OCTA system. After excluding the central 1 mm diameter circle, the EAA on superficial vascular complex was measured with a deep-learning-based algorithm, and the EVD was obtained with commercial software.

RESULTS

The study included 34 healthy controls and 118 diabetic patients. EAA and EVD were highly correlated with DR severity (ρ=0.812 and -0.577, respectively, both p<0.001) and visual acuity (r=-0.357 and 0.420, respectively, both p<0.001). EAA had a significantly (p<0.001) higher correlation with DR severity than EVD. With the specificity at 95%, the sensitivities of EAA for differentiating diabetes mellitus (DM), DR and severe DR from control were 80.5%, 92.0% and 100.0%, respectively, significantly higher than those of EVD 11.9% (p=0.001), 13.6% (p<0.001) and 15.8% (p<0.001), respectively. EVD was significantly correlated with signal strength index (SSI) (r=0.607, p<0.001) and shadow area (r=-0.530, p<0.001), but EAA was not (r=-0.044, p=0.805 and r=-0.046, p=0.796, respectively). Adjustment of EVD with SSI and shadow area lowered sensitivities for detection of DM, DR and severe DR.

CONCLUSION

Macular EAA on 6×6 mm OCTA measured with a deep learning-based algorithm is less dependent on the signal strength and shadow artefacts, and provides better diagnostic accuracy for DR severity than EVD measured with the instrument-embedded software.

Detection of neovascularisation in the vitreoretinal interface slab using widefield swept-source optical coherence tomography angiography in diabetic retinopathy

AIMS

To compare the efficacy of diabetic retinal neovascularisation (NV) detection using the widefield swept-source optical coherence tomography angiography (WF SS-OCTA) vitreoretinal interface (VRI) Angio slab and SS-OCT VRI Structure slab.

METHODS

A prospective, observational study was performed at Massachusetts Eye and Ear from January 2019 to June 2020. Patients with proliferative diabetic retinopathy (PDR), patients with non-proliferative diabetic retinopathy and patients with diabetes but without diabetic retinopathy were included. All patients were imaged with WF SS-OCTA using the 12×12 mm Angio scan protocol centred on the fovea and optic disc. The en-face SS-OCTA VRI Angio slab and SS-OCT VRI Structure slab were evaluated for the presence or absence of NV. SS-OCTA B-scan was used to classify NV according to cross-sectional morphology (forward, tabletop or flat). All statistical analyses were performed using SPSS V.26.0.

RESULTS

One hundred and forty-two eyes of 89 participants were included in the study. VRI Angio detected NV at higher rates compared with VRI Structure (p<0.05). Combining VRI Angio and Structure improved detection rates compared with VRI Angio alone (p<0.05). Due to segmentation errors of the internal limiting membrane, NV with flat morphological classification had lower rates of detection on VRI Angio compared with NV with forward and tabletop morphology (p<0.05).

CONCLUSIONS

WF SS-OCTA 12×12 mm VRI Angio and SS-OCT VRI Structure imaging centred on the fovea and optic disc detected NV with high sensitivity and low false positives. The VRI slab may be useful to diagnose and monitor PDR in clinical practice.

Utilisation of optical coherence tomography and optical coherence tomography angiography to assess retinal neovascularisation in diabetic retinopathy

PURPOSE

To evaluate the use of optical coherence tomography angiography (OCTA), structural OCT and fundus fluorescein angiography (FFA) to distinguish neovascularisation elsewhere (NVE) from intra retinal microvascular abnormalities (IRMA) and their use in early detection and possible risk assessment for vitreous haemorrhage.

METHODS

A cross-sectional study of a consecutive series of patients with suspected NVE and IRMA using clinical examination and FFA, were examined further with OCT and OCTA. Treated and untreated eyes were also compared.

RESULTS

Images from 33 eyes of 26 patients, showed 27 NVE and 14 IRMA lesions based on clinical examination +/- FFA. Lesions were re-classified as NVE in 22 eyes. Ten eyes had received past treatment. In all 10 treated eyes, vascular flow and vitreous connection were found but not FFA leakage. In 18/22 eyes with NVE there was a breach of the internal limiting membrane (ILM), in 4 eyes there was FFA leak, ILM outpouching but no breach. In two eyes, NVE originated from sea fan IRMA. Ten eyes images were classified as IRMA only with no FFA leak, or ILM breach. The relation of pre-retinal NVE to the vitreous can be visualised.

CONCLUSION

Lesions, considered to be NVE, after further assessment with OCT and OCTA, can be intra-retinal, with ILM disruption but no ILM breach and leakage on FFA. ILM disruption maybe one of the earliest signs of the development of neovascularisation. Visualisation of the relation to the posterior vitreous is likely to be useful in assessing risk of vitreous haemorrhage.

AN ATYPICAL CASE OF OPTIC DISK PSEUDO-DUPLICATION WITH PROLIFERATIVE DIABETIC RETINOPATHY

PURPOSE

To present a unique case of optic disk pseudo-duplication with proliferative diabetic retinopathy.

METHODS

Case report.

RESULTS

A 63-year-old white diabetic man presented with an apparent duplicated optic disk in the superonasal midperiphery of his left eye. A large flat frond of neovascularization fanned out from this structure. Optical coherence tomography scanning showed a noncolobomatous scar with a large plume of blood vessels sprouting from the choroid, thru the retina and branching out into the vitreous. Magnetic resonance imaging scanning revealed a normal left globe and orbit with a single optic nerve. The neovascularization regressed after panretinal photocoagulation and anti-vascular endothelial growth factor therapy.

CONCLUSION

We describe a unique case of proliferative diabetic retinopathy associated with pseudo-duplication of the optic disk. This case is unique in the peripheral location of the pseudo-duplication, the presence of spontaneous choroidovitreal neovascularization in proliferative diabetic retinopathy, and the appearance of neovascularization elsewhere mimicking neovascularization of the duplicated disk.

Role of Optical Coherence Tomography Angiography to differentiate Intraretinal microvascular abnormalities and retinal neovascularization in Diabetic Retinopathy

Objective

To assess proliferative diabetic retinopathy (PDR) and to describe the difference in angiographic representation of new vessels (NVs) and Intra retinal microvascular abnormalities (IRMA) on optical coherence tomography angiography (OCTA).

Methods

A cross-sectional observational study was performed at ISRA Postgraduate Institute of Ophthalmology, Karachi, from March 2018 to September 2018. Forty-two eyes of 21 patients with history of diabetes mellitus (DM) were examined. Twenty-eight eyes with a clinical diagnosis of severe non proliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR) according to early treatment diabetic retinopathy study (ETDRS) were included and evaluated using Swept source optical coherence tomography angiography (SS-OCTA). Then face wide field SS-OCTA images and co registered structural optical coherence tomography (OCT) with flow overlay were used to distinguish the features of IRMA and retinal NVs.

Results

Forty-two eyes (21 patients) were examined clinically. Fourteen eyes had moderate NPDR, 15 had severe NPDR and 13 eyes had changes consistent with PDR. After clinical diagnosis, we included 28 eyes in our study based on inclusion criteria. These 28 eyes went through SS-OCTA evaluation and we observed 15 cases with PDR and 13 with severe NPDR changes. The OCTA and clinical diagnosis were similar except in 2 eyes, which is critical but not statically significant showing the importance of this noninvasive technology.

Conclusions

Widefield OCTA can work as an alternative to fundus fluorescein angiography (FFA) in the diagnosis of diabetic retinopathy (DR). As it is a non-invasive and depth encoded technique so can be used frequently to monitor the retinal changes and their progression.

Optical Coherence Tomography Angiography in Diabetic Patients: A Systematic Review

Background: Diabetic retinopathy (DR) is the leading cause of legal blindness in the working population in developed countries. Optical coherence tomography (OCT) angiography (OCTA) has risen as an essential tool in the diagnosis and control of diabetic patients, with and without DR, allowing visualisation of the retinal and choroidal microvasculature, their qualitative and quantitative changes, the progression of vascular disease, quantification of ischaemic areas, and the detection of preclinical changes. The aim of this article is to analyse the current applications of OCTA and provide an updated overview of them in the evaluation of DR. Methods: A systematic literature search was performed in PubMed and Embase, including the keywords “OCTA” OR “OCT angiography” OR “optical coherence tomography angiography” AND “diabetes” OR “diabetes mellitus” OR “diabetic retinopathy” OR “diabetic maculopathy” OR “diabetic macular oedema” OR “diabetic macular ischaemia”. Of the 1456 studies initially identified, 107 studies were screened after duplication, and those articles that did not meet the selection criteria were removed. Finally, after looking for missing data, we included 135 studies in this review. Results: We present the common and distinctive findings in the analysed papers after the literature search including the diagnostic use of OCTA in diabetes mellitus (DM) patients. We describe previous findings in retinal vascularization, including microaneurysms, foveal avascular zone (FAZ) changes in both size and morphology, changes in vascular perfusion, the appearance of retinal microvascular abnormalities or new vessels, and diabetic macular oedema (DME) and the use of deep learning technology applied to this disease. Conclusion: OCTA findings enable the diagnosis and follow-up of DM patients, including those with no detectable lesions with other devices. The evaluation of retinal and choroidal plexuses using OCTA is a fundamental tool for the diagnosis and prognosis of DR.

Optical coherence tomography-angiography in diabetic retinopathy diagnosis and monitoring

Optical coherence tomography-angiography is a modern noninvasive method of 3D imaging and quantitative analysis of the retinal and choroidal microvasculature. It allows detecting manifestation and progression of diabetic retinopathy, planning treatment and evaluating its results.Optical coherence tomography angiography expands our understanding of microvascular changes in retinal vascular plexuses at different disease stages and deepens the understanding of its pathogenesis.

Contribution of optical coherence tomography angiography OCT-A in diabetic maculopathy

Introduction

Diabetic retinopathy (DR) increases the risk of blindness by 25 times. Advanced researchs are justified for better management, leading to the role of Optical Coherence Tomography-Angiography (OCT-A), a new non-invasive imaging technique exploring retinal vascularization.

Our purpose is to identify microvascular macular anomalies of DR on OCT-A with qualitative and quantitative evaluation of their impact on retinal vascularization.

Patients and methods

This is a descriptive cross-sectional study where 120 eyes of 66 diabetic patients were enrolled. All patients were diabetic and went through OCT-A imaging.

Results

Microanevrysms were identified in both superficial capillary plexus (SCP) and deep capillary plexus (DCP) where they were more frequently visualized. Macular edema was present in 16,7% of cases in the SCP, and in 30% in DCP. Edema spaces were more frequently present in DCP (p < 0,05). Capillary nonperfusion areas were identified in 82,5% of cases in SCP and in 60% of cases in DCP. The main peri-foveal vascular density was 18,95 ± 5,37%. The main surface of foveal avascular zone (FAZ) in the SCP was 462,52 μm² and was 555,04 ± 329,11 μm² in the DCP where it was larger.

Conclusion

OCT-A is a modern imaging tool that could be used for the diagnosis and monitoring of DR as well as the understanding of its pathophysiology.

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Retinal microvascular abnormalities on OCT-A are observed in diabetic retinopathy and are proportional to its severity.

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Deep capillary plexus was more severely affected than superficial capillary plexus.

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The assessment of macular ischemia could be based on the identification of areas of vascular rarefaction.

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Quantitative assessment of vascular density and the study of the foveal avascular zone can assess the macular ischemia

Update on Optical Coherence Tomography and Optical Coherence Tomography Angiography Imaging in Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy (PDR) is a major cause of blindness in diabetic individuals. Optical coherence tomography (OCT) and OCT-angiography (OCTA) are noninvasive imaging techniques useful for the diagnosis and assessment of PDR. We aim to review several recent developments using OCT and discuss their present and potential future applications in the clinical setting. An electronic database search was performed so as to include all studies assessing OCT and/or OCTA findings in PDR patients published from 1 January 2020 to 31 May 2021. Thirty studies were included, and the most recently published data essentially focused on the higher detection rate of neovascularization obtained with widefield-OCT and/or OCTA (WF-OCT/OCTA) and on the increasing quality of retinal imaging with quality levels non-inferior to widefield-fluorescein angiography (WF-FA). There were also significant developments in the study of retinal nonperfusion areas (NPAs) using these techniques and research on the impact of PDR treatment on NPAs and on vascular density. It is becoming increasingly clear that it is critical to use adequate imaging protocols focused on optimized segmentation and maximized imaged retinal area, with ongoing technological development through artificial intelligence and deep learning. These latest findings emphasize the growing applicability and role of noninvasive imaging in managing PDR with the added benefit of avoiding the repetition of invasive conventional FA.

Characterizing Flow and Structure of Diabetic Retinal Neovascularization after Intravitreal Anti-VEGF Using Optical Coherence Tomography Angiography: A Pilot Study

Background/Aims. This study evaluates changes of flow and structure of diabetic retinal neovascularization (NV) treated with intravitreal antivascular endothelial growth factor (VEGF) agents using optical coherence tomography angiography (OCTA). With OCTA, retinal blood vessels are visualized at high resolution to separately look at flow and structure information without the need for dye injection. We introduce a new measurement method including and combining information of flow and structure. Methods. Retrospective observational case series. Patients with proliferative diabetic retinopathy (PDR) were treated with intravitreal antiVEGF injections. Retinal NV were repeatedly imaged using swept-source OCTA (Zeiss PlexElite 9000) at baseline, after initial treatment block with 3-4 monthly injections, and during a follow-up period of up to 51 weeks. Change of size and flow density of the structural and angio area of NV was assessed. Results. Nine NV in eight eyes of five patients were analyzed with a median follow-up time of 45 weeks. After the initial treatment block, en face structural area regressed, 18.7% ± 39.0% (95% CI 44.2–6.8%, p=0.26), and en face angio area regressed, 51.9% ± 29.5% (95% CI 32.6 to 71.2%, p=0.007). Flow density within the en face structural area decreased by 33% ± 19.2% (95% CI 20.5–45.5%, p=0.0077). Flow density within the en face angio area decreased by mean 17.9% ± 25.2% (95% CI 1.4–34.4%, p=0.066). In two fellow eyes, NV recurrence could be observed before the onset of vitreous bleeding in one. Conclusion. Our study introduces a new quantitative measurement for NV in PDR, combining structure and flow measurement. The structure area remained after treatment, while its flow density and angio area regressed. We propose this measurement method as a more physiological and possibly more comparable metrics.

NOVEL THREE TYPES OF NEOVASCULARIZATION ELSEWHERE DETERMINE THE DIFFERENTIAL CLINICAL FEATURES OF PROLIFERATIVE DIABETIC RETINOPATHY

PURPOSE

To explore the pathological features and clinical significance of three types of neovascularization elsewhere (NVE) in proliferative diabetic retinopathy.

METHODS

Neovascularization elsewhere was classified based on the origins and morphologic features using fluorescein angiography and angiographic and structural optical coherence tomography. The topographical distribution, vitreoretinal interface, and responsiveness to panretinal photocoagulation were compared among three types of NVE.

RESULTS

One hundred and twenty-seven NVEs were classified into three types. Type 1 NVE was concentrated along or adjacent to vascular arcades; Type 2 was distributed more peripherally than were Types 1 and 3 NVE. The arch bridge-like vitreoretinal interface accounted for 79% of Type 1 NVE. The flat and flat-forward vitreoretinal interface accounted for 95% and 100% in Type 2 and Type 3 NVE, respectively. At 3 months after panretinal photocoagulation, the regression rates for Types 1, 2, and 3 NVE were 82%, 100%, and 80%, respectively. Type 2 NVE showed best regression rate after panretinal photocoagulation (both P < 0.01).

CONCLUSION

Three types of NVE determine the distinctly topographical distributions, vitreoretinal interface features, and differential responsiveness to panretinal photocoagulation treatment. This new concept may have important clinical implications in assessing the treatment and prognosis of proliferative diabetic retinopathy.

Analysis of Progressive Neovascularization in Diabetic Retinopathy Using Widefield OCT Angiography

PURPOSE

To document enlarged neovascularization elsewhere (NVE) quantitatively and morphologically using widefield swept-source (SS) OCT angiography (OCTA) with vitreoretinal interface (VRI) slab images.

DESIGN

Retrospective, observational imaging study.

PARTICIPANTS

The study included 46 NVE examples in 25 eyes of 21 consecutive patients who demonstrated severe proliferative diabetic retinopathy with NVE between March 2018 and June 2020 at Osaka University Hospital.

METHODS

All patients underwent ophthalmologic examination, including ultra-widefield fluorescein angiography and widefield SS OCTA scans.

MAIN OUTCOME MEASURES

We evaluated the area and the vascular density (VD) of NVE lesions detected on five 12 × 12-mm² or two 15 × 9-mm² SS OCTA panoramic VRI slab images obtained at the first and final visits.

RESULTS

At baseline, the mean NVE area on OCTA was 1.85 ± 2.81 mm², and the VD of the NVE lesions was 73.9 ± 14.6%. At the final visit, the mean NVE area on OCTA was 2.14 ± 3.14 mm², and the mean VD of the NVE lesions was 65.3 ± 17.1%. The average NVE size change (square millimeters per month) was associated significantly with the ischemic index (P = 0.009). Growth of NVE area was classified into 2 patterns: round (61.8%) and ramified (38.2%). The round group tended to have a larger ischemic index at baseline than the ramified group (P = 0.0375).

CONCLUSIONS

We quantified the size and density of NVE lesions over time. The NVE size increase was associated significantly with the severity of ischemic changes. Furthermore, the round growth pattern was correlated significantly with the ischemic index. These findings suggest that the morphologic features of NVE are associated with more severe ischemia.

Repeatability of Peripapillary Optical Coherence Tomography Angiography Parameters in Older Adults

Purpose:

This work assesses the intrasession repeatability of capillary perfusion density (CPD) and capillary flux index (CFI) measurements on peripapillary optical coherence tomography angiography (OCTA) in healthy eyes of older adults.

Methods:

In this cross-sectional study, healthy volunteers aged 50 years or older underwent 4.5 × 4.5 mm OCTA imaging centered on the optic nerve head using Zeiss Cirrus HD-5000 AngioPlex (Carl Zeiss Meditec). Two consecutive images were acquired in the same eye during a single study session. CPD and CFI were assessed using AngioPlex Software (version 11.0.0.29946) for the radial peripapillary capillary plexus (average over whole scan area) and 4 quadrants (superior, inferior, temporal, and nasal). CPD and CFI repeatability was assessed by intraclass correlation (ICC), mean interocular differences using 2-tailed t test, and association with age using generalized estimating equations.

Results:

A total of 150 images were acquired from 75 eyes of 47 patients. For CPD, ICC results ranged from 0.7160 (nasal CPD) to 0.9218 (average CPD). For CFI, ICC results ranged from 0.6167 (temporal CFI) to 0.8976 (inferior CFI). Temporal CFI was significantly different between right and left eyes of the same patient ( P = .03). CPD and CFI decreased with age in all analyses (average CPD β coefficient –0.00172, P < .001; average CFI β coefficient −0.00278, P < .001).

Conclusions:

Moderate to good repeatability was observed for most peripapillary OCTA metrics; temporal measurements were least repeatable for CPD and CFI. Peripapillary CPD and CFI decrease with age even beyond the fifth decade in healthy older adults.

Quantitative analysis of vascular changes during photoimmunotherapy using speckle variance optical coherence tomography (SV-OCT)

Near-infrared (NIR) photoimmunotherapy (NIR-PIT) is an emerging cancer therapy based on a monoclonal antibody and phthalocyanine dye conjugate. Direct tumor necrosis and immunogenic cell death occur during NIR irradiation. However, the alteration of tumor blood vessels and blood volume inside the blood vessels induced by the NIR-PIT process is still unknown. In our study, a speckle variance (SV) algorithm combined with optical coherence tomography (OCT) technology was applied to monitor the change of blood vessels and the alterations of the blood volume inside the blood vessels during and after NIR-PIT treatment. Vascular density and the measurable diameter of the lumen in the blood vessel (the diameter of the region filled with blood) were extracted for quantitively uncovering the alterations of blood vessels and blood volume induced by NIR-PIT treatment. The results indicate that both the density and the diameter of the lumen in the blood vessels decrease during the NIR-PIT process, while histological results indicated the blood vessels were dilated. The increase of permeability of blood vessels could lead to the increase of the blood pool volume within the tumor (shown in histology) and results in the decrease of free-moving red blood cells inside the blood vessels (shown in SV-OCT).

Widefield Swept-Source OCT Angiography Metrics Associated with the Development of Diabetic Vitreous Hemorrhage: A Prospective Study

PURPOSE

To investigate the association among widefield swept-source (SS) OCT angiography (OCTA) metrics and systemic parameters and vitreous hemorrhage (VH) occurrence in eyes with proliferative diabetic retinopathy (PDR).

DESIGN

Prospective, observational study.

PARTICIPANTS

Fifty-five eyes from 45 adults with PDR, with no history of VH, followed up for at least 3 months.

METHODS

All patients underwent widefield SS OCTA (Montage 15 × 15 mm and high-definition (HD)-51 line scan) imaging. Images were evaluated independently by 2 graders for quantitative and qualitative widefield SS OCTA metrics defined a priori. Systemic and ocular parameters and widefield SS OCTA metrics were screened using least absolute shrinkage and selection operator and logistic or Cox regression for variable selection. Firth's bias-reduced logistic regression models (outcome, occurrence of VH) and Cox regression models (outcome, time to occurrence of VH) were used to identify parameters associated with VH occurrence.

MAIN OUTCOME MEASURES

Occurrence of VH.

RESULTS

Over a median follow-up of 363 days (range, 28-710 days), 13 of 55 PDR eyes (24%) demonstrated VH during the follow-up period. Presence of extensive neovascularizations (odds ratio, 8.05; 95% confidence interval [CI], 1.43-58.56; P = 0.02), defined as neovascularizations with total area of more than 4 disc diameters, and forward neovascularizations (odds ratio, 5.42; 95% CI, 1.26-35.16; P = 0.02) that traversed the posterior hyaloid face into the vitreous were associated with the occurrence of VH. The presence of flat neovascularizations (odds ratio, 0.25; 95% CI, 0.04-1.01; P = 0.05) confined to the posterior hyaloid face was associated with a lower risk of VH with borderline significance. Similarly, presence of extensive neovascularizations (hazard ratio, 18.24; 95% CI, 3.51-119.47; P < 0.001) and forward neovascularizations (hazard ratio, 9.60; 95% CI, 2.07-68.08; P = 0.002) was associated significantly with time to development of VH.

CONCLUSIONS

Widefield SS OCTA is useful for evaluating neovascularizations and their relationship with the vitreous. The presence of forward and extensive neovascularizations was associated with the occurrence of VH in patients with PDR. Larger samples and longer follow-up are needed to verify the risk factors and imaging biomarkers for diabetic VH.

Analyzing Relative Flow Speeds in Diabetic Retinopathy Using Variable Interscan Time Analysis OCT Angiography

PURPOSE

Further insight into the flow characteristics of the vascular features associated with diabetic retinopathy (DR) may improve assessment and treatment of disease progression. The variable interscan time analysis (VISTA) algorithm is an extension of OCT angiography (OCTA) that detects relative blood flow speeds, which then can be depicted on a color-coded map. This study used VISTA to analyze relative blood flow speeds in the microvascular changes associated with DR.

DESIGN

Cross-sectional study.

PARTICIPANTS

Thirteen patients with varying severities of DR treated at New England Eye Center, Boston, Massachusetts.

METHODS

OCT angiography images centered at the fovea were obtained on a prototype swept-source OCT device, and the VISTA algorithm was applied to visualize relative blood flow speeds.

MAIN OUTCOME MEASURES

Descriptive flow analysis of the retinal vascular features of DR was conducted on the VISTA-generated images.

RESULTS

Twenty-six eyes were included in this study. Of these, 3 eyes had mild nonproliferative DR (NPDR), 6 eyes had moderate NPDR, 4 eyes had severe NPDR, 9 eyes had proliferative DR, and 4 eyes were normal controls. Microaneurysms, intraretinal microvascular abnormalities (IRMAs), and neovascularization appeared to originate from areas of relatively slow blood flow speeds. Microaneurysms showed relatively slower flow, IRMAs showed turbulent, intermediate to slow flow, and venous beading and looping presented with relatively high flow speeds that tapered progressively. Neovascularization of venous origin demonstrated slower flow speeds, whereas that of arterial origin showed relatively high flow speeds. Additionally, increased disease severity was associated with globally slower flow speeds, with particularly slower flow around the foveal avascular zone.

CONCLUSIONS

The VISTA algorithm seems to be a useful extension of OCTA that overcomes some of the limitations of normal gray-scale OCTA. It seems to have some potential in providing relevant insight into the pathogenesis of the microvascular changes associated with DR. These findings may assist in improving our understanding of the pathogenic changes that take place in DR.

OCT-Angiography as a reliable prognostic tool in laser-treated proliferative diabetic retinopathy: The RENOCTA Study

PURPOSE

To quantitatively assess retinal neovascularizations (RNVs) in proliferative diabetic retinopathy (PDR) before and after photocoagulative laser treatment (PLT) using Optical Coherence Tomography Angiography (OCT-A).

METHODS

Consecutive patients with PDR were examined with fluorescein angiography (FA) and OCT-A before and after PLT. Baseline and after-treatment FA images were quantitatively analyzed to assess both the RNVs area and leakage area. On OCT-A RNVs area, vascular perfusion density (VPD), vessel length density (VLD) and fractal dimension were computed. VPD of the full-retina OCT-A underneath the RNV was determined to evaluate potential laser-induced changes in vascular perfusion.

RESULTS

Fifteen eyes of 13 patients with PDR were enrolled. The mean area of the RNVs was 0.47 ± 0.50 mm² in the baseline OCT-A and 0.32 ± 0.40 mm² in the post-treatment assessment (p = 0.0002). The mean RNV VPD of RNV was 2% ± 4% in pre-treatment and 1% ± 1% for the post-treatment (p = 0.0001). The mean VLD of RNV was 7.26 ± 1.53 at baseline and 6.64 ± 1.65 in the post treatment (p = 0.0002). A significant difference in terms of mean RNVs area and VPD reduction between eyes that needed additional treatment and those that did not (~40% vs ~20%; p < 0.05), was observed. Mean VPD of full-retinal thickness OCT-angiogram was 55% ± 10% for the pre-treatment and 53% ± 8% for the post treatment scan (p = 0.02).

CONCLUSION

The quantitative OCT-A assessment of laser-induced changes of RNVs can be a useful non-invasive approach for determining treatment efficacy. A reduction of RNVs area or VPD ⩾ 40% might reveal those eyes that won't require additional treatment. Retinal perfusion impairment seemed to progress independently from the treatment.

Optical coherence tomography angiography in diabetic retinopathy: an updated review

Diabetic retinopathy (DR) is a common microvascular complication of diabetes mellitus. Optical coherence tomography angiography (OCTA) has been developed to visualize the retinal microvasculature and choriocapillaris based on the motion contrast of circulating blood cells. Depth-resolved ability and non-invasive nature of OCTA allow for repeated examinations and visualization of microvasculature at the retinal capillary plexuses and choriocapillaris. OCTA enables quantification of microvascular alterations in the retinal capillary network, in addition to the detection of classical features associated with DR, including microaneurysms, intraretinal microvascular abnormalities, and neovascularization. OCTA has a promising role as an objective tool for quantifying extent of microvascular damage and identify eyes with diabetic macular ischaemia contributed to visual loss. Furthermore, OCTA can identify preclinical microvascular abnormalities preceding the onset of clinically detectable DR. In this review, we focused on the applications of OCTA derived quantitative metrics that are relevant to early detection, staging and progression of DR. Advancement of OCTA technology in clinical research will ultimately lead to enhancement of individualised management of DR and prevention of visual impairment in patients with diabetes.

Optical Coherence Tomography Angiography Features of Neovascularization in Proliferative Diabetic Retinopathy

Purpose

To describe features of neovascularization in proliferative diabetic retinopathy (PDR) using optical coherence tomography angiography (OCTA).

Methods

A retrospective case series was performed in 23 eyes from 21 patients who underwent OCTA of neovascular complexes (NVCs) due to PDR. Eyes were imaged with the DRI Triton swept-source OCTA, Avanti RTVue XR or Cirrus HD-OCT 5000 as part of routine clinical examination. Segmentation was adjusted to include vasculature between the vitreous cavity and the internal limiting membrane (ILM). The presence of NVCs was confirmed by clinical examination and multimodal imaging such as color or red-free fundus photography, fluorescein angiography, multicolor imaging or near-infrared reflectance.

Results

Thirty-five NVCs were imaged, of which, 34% were neovascularization of the disc (NVD) and 66% were neovascularization elsewhere (NVE). On structural OCT B-scans, NVE appeared as medium to highly reflective tissue that breached the ILM, while NVD showed highly reflective tissue protruding from the disc in a sea fan configuration. Flow signal was seen on OCTA in all cases of NVE and in 67% of NVD lesions. Areas with minimal or absent retinal flow signal identified retinal nonperfusion areas and were found adjacent to 87% of NVE. Intraretinal microvascular abnormalities (IRMAs) were noted next to 70% of NVE. Absent flow signal was seen in 4 NVD cases showing posterior shadowing and were considered inactive.

Conclusion

OCTA appears useful for imaging NVCs, IRMAs, and retinal nonperfusion areas in eyes with diabetic retinopathy. This imaging modality enables noninvasive screening and monitoring of PDR and can obviate the need for additional testing in certain clinical settings.

<p>Ultra-Widefield Fluorescein Angiographic Patterns, Retinal Microvascular Anomalies and Retinal Ischemic Index in Branch Retinal Vein Occlusions with Established Retinal Neovascularization</p>

Purpose

To share the experience of using ultra-widefield fluorescein angiography (UWF-FA) in recognizing the potential signs for retinal neovascularizations (NVE) development in branch retinal vein occlusions (BRVO).

Methods

Reporting angiographic findings in 60 BRVO eyes presenting with NVE and vitreous hemorrhage using UWF-FA investigation. Angiographic retinal ischemic index (ARI) was also calculated from UWF-FA as the ratio of digitally mapped ischemic retina area against area of optic disc, termed unit of disc diameter (DD).

Results

We observed emerging angiographic features common to these patients: pattern of a localized non-perfused retina at early phase of UWF-FA remaining non-perfused at the late phase (black retinal ischemia, black-RI) (100%); presence of retinal microvascular anomalies (RMAs) at the “water-shed-border” of black-RI (100%); site of NVEs observed at either the same “water-shed-border” (42%) or from the main vessel branch within the black-RI (30%), or from both sites (28%); multiple NVEs were observed in all eyes except two with single active NVE. Median ARI size was 114 DD (SD 80 DD), range 5–354 DD.

Conclusion

We report a recurring angiographic pattern common to eyes with active BRVO-NVEs from UWF-FA, and NVEs in this clinical group can develop from varied ARI sizes. Further studies would be needed to establish the role of UWF-FA in predicting angiographic risk factors for BRVO-NVE.

New developments in angiography for the diagnosis and management of diabetic retinopathy

The most common microvascular complication of diabetes is diabetic retinopathy, the leading cause of blindness in adults of working age. Our understanding of the vascular changes in diabetic retinopathy was enhanced by the demonstration of fluorescein angiography (FA) in the human retina for the first time in 1961. It was subsequently integrated with digital fundoscopic imaging to become an invaluable technique in evaluation of the retinal vasculature. The recent development of OCT-angiography (OCT-A) has revolutionized the clinician's ability to examine the retinal vasculature without the need for injection of a contrast dye. By coupling OCT, which can provide noninvasive cross-sectional imaging of the central retina, with angiography in OCT-A, one can reveal retinal perfusion by allowing visualization of the depth-resolved retinal capillary plexus. OCT-A has allowed for more precise delineation of changes in the retinal microvasculature, specifically the alterations of retinal vasculature and loss of capillary perfusion from chronic microvascular occlusion in diabetic retinopathy.

A Proposed Classification of Intraretinal Microvascular Abnormalities in Diabetic Retinopathy Following Panretinal Photocoagulation

Purpose

To investigate the characteristics of intraretinal microvascular abnormalities (IRMAs) before and after panretinal photocoagulation (PRP) for diabetic retinopathy (DR) by using optical coherence tomography angiography (OCTA).

Methods

Forty-six eyes of 29 patients with DR were included (26 eyes with severe nonproliferative diabetic retinopathy [SNPDR] and 20 eyes with proliferative diabetic retinopathy [PDR]). En face OCTA images of IRMAs in a 6 × 6-mm area were acquired by using Cirrus 5000 with AngioPlex. The morphological changes in IRMAs were evaluated before and after PRP. The changes in the IRMAs were divided into five subtypes: unchanged; tuft regression; reperfusion; mixed (combined tuft regression/reperfusion); and worsening (new appearance of tuft).

Results

Unchanged IRMAs were identified in 15 SNPDR eyes and 2 PDR eyes; all neovascularization (NV) had regressed after PRP. Tufts were more frequently observed in the PDR eyes (15/20, 75%) than in the SNPDR eyes (8/26, 31%) (P = 0.003), and two tufts tended to exceed the inner limiting membrane, which showed progression to NV before PRP. The reperfusion phenomenon was observed in 7/26 SNPDR eyes and 4/20 PDR eyes, including the mixed type, and showed two vascular patterns: abnormal (dilated, tortuous, and twisted) and normal vessels. The worsening type was observed in 1/26 SNPDR eye and 2/20 PDR eyes.

Conclusions

OCTA enabled classification of IRMA into more detailed types. The unchanged and reperfusion types suggested that IRMAs had aspects of remodeling. However, IRMAs with tufts were observed in 75% of the PDR eyes, and the tufts had aspects of NV.

Different Scan Protocols Affect the Detection Rates of Diabetic Retinopathy Lesions by Wide-Field Swept-Source Optical Coherence Tomography Angiography

PURPOSE

To compare different scan protocols of wide-field swept-source optical coherence tomography angiography (SS-OCTA) for the detection of diabetic retinopathy (DR) lesions.

DESIGN

Comparison of diagnostic approaches.

METHODS

A prospective, observational study was conducted at Massachusetts Eye and Ear from December 2018 to July 2019. Proliferative diabetic retinopathy (PDR), nonproliferative diabetic retinopathy (NPDR), and diabetic patients without DR were included. All patients were imaged using SS-OCTA using the following scan protocol: 3- × 3-mm Angio centered on the fovea; 6- × 6-mm Angio centered on the fovea and the optic disc; 15- × 9-mm Montage; and 12- × 12-mm Angio centered on the fovea and the optic disc. Images were independently evaluated by 2 graders for the presence or absence of DR lesions including microaneurysms, intraretinal microvascular abnormalities, neovascularization, nonperfusion areas, venous looping, and hard exudates. All statistical analyses were performed using commercial software.

RESULTS

A total of 176 eyes in 119 participants were included in the study. The detection rate of neovascularization on 6- × 6-mm Angio centered on the fovea was approximately one-half that on 15- × 9-mm Montage (P < .05) imaging. Combining 6- × 6-mm Angio imaging centered on the fovea and the optic disc could increase the rate to approximately two-thirds (P < .05). The 12- × 12-mm Angio imaging centered on the combination of fovea and optic disc had detection rates comparable to those of 15- × 9-mm Montage imaging for all DR lesions (P > .05). For microaneurysms, 6- × 6-mm Angio had better performance than 15- × 9-mm Montage (P < .05).

CONCLUSIONS

Wide-field SS-OCTA images were useful in detecting DR lesions. The 12- × 12-mm Angio imaging centered on the fovea and on the optic disc may be an optimal balance between speed and efficacy for evaluation of DR in clinical practice.

Optical coherence tomography features of neovascularization in proliferative diabetic retinopathy: a systematic review

Background

Diabetic retinopathy (DR) is a leading cause of blindness due to diabetic macular edema (DME) or complications of proliferative diabetic retinopathy (PDR). Optical coherence tomography (OCT) is a noninvasive imaging technique well established for DME but less used to assess neovascularization in PDR. Developments in OCT imaging and the introduction of OCT angiography (OCTA) have shown significant potential in PDR.

Objectives

To describe the tomographic features of PDR, namely of neovascularization, both of the optic disc (NVD) and elsewhere (NVE), intraretinal microvascular abnormalities (IRMA), retinal nonperfusion areas (NPA), status of the posterior vitreous, vitreoschisis and vitreous and subhyaloid/sub-ILM hemorrhages.

Data sources

Electronic database search on PubMed and EMBASE, last run on December 19th 2019.

Study eligibility criteria, participants and interventions

Publications assessing OCT and/or OCTA findings in PDR patients. All study designs were allowed except for case-reports, conference proceedings and letters.

Study appraisal

Newcastle–Ottawa Scale for observational studies was used for purposes of risk of bias assessment.

Results

From the 1300 studies identified, 283 proceeded to full-text assessment and 60 were included in this comprehensive review. OCT was useful in detecting NVD and NVE, such as in characterizing disease activity and response to laser and/or anti-VEGF therapies. The absence of posterior vitreous detachment seemed determinant for neovascular growth, with the posterior hyaloid acting as a scaffold. OCTA allowed a more detailed characterization of the neovascular complexes, associated NPA and disease activity, allowing the quantification of neovessel area and flow index. However, changes in OCTA blood flow signal following local therapies did not necessarily correlate with structural regression. Widefield and ultra-widefield OCTA were highly sensitive in the detection of PDR, adding value to disease staging and monitoring. Compared to fluorescein angiography, OCTA was more sensitive in detecting microvascular changes indicating disease progression.

Limitations

Publication languages were restricted. Most included studies were observational and non-comparative. Risk of bias regarding case representativeness.

Conclusions

OCT-based retinal imaging technologies are advancing rapidly and the trend is to be noninvasive and wide-field. OCT has proven invaluable in diagnosing, staging and management of proliferative diabetic disease with daily application in clinical and surgical practices.

Comparison of widefield swept-source optical coherence tomography angiography with ultra-widefield colour fundus photography and fluorescein angiography for detection of lesions in diabetic retinopathy

AIMS

To compare widefield swept-source optical coherence tomography angiography (WF SS-OCTA) with ultra-widefield colour fundus photography (UWF CFP) and fluorescein angiography (UWF FA) for detecting diabetic retinopathy (DR) lesions.

METHODS

This prospective, observational study was conducted at Massachusetts Eye and Ear from December 2018 to October 2019. Proliferative DR, non-proliferative DR and diabetic patients with no DR were included. All patients were imaged with a WF SS-OCTA using a Montage 15×15 mm scan. UWF CFP and UWF FA were taken by a 200°, single capture retinal imaging system. Images were independently evaluated for the presence or absence of DR lesions including microaneurysms (MAs), intraretinal microvascular abnormalities (IRMAs), neovascularisation elsewhere (NVE), neovascularisation of the optic disc (NVD) and non-perfusion areas (NPAs). All statistical analyses were performed using SPSS V.25.0.

RESULTS

One hundred and fifty-two eyes of 101 participants were included in the study. When compared with UWF CFP, WF SS-OCTA was found to be superior in detecting IRMAs (p<0.001) and NVE/NVD (p=0.007). The detection rates of MAs, IRMAs, NVE/NVD and NPAs in WF SS-OCTA were comparable with UWF FA images (p>0.05). Furthermore, when we compared WF SS-OCTA plus UWF CFP with UWF FA, the detection rates of MAs, IRMAs, NVE/NVD and NPAs were identical (p>0.005). Agreement (κ=0.916) between OCTA and FA in classifying DR was excellent.

CONCLUSION

WF SS-OCTA is useful for identification of DR lesions. WF SS-OCTA plus UWF CFP may offer a less invasive alternative to FA for DR diagnosis.

Optical Coherence Tomography Angiography in Diabetes and Diabetic Retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes mellitus that disrupts the retinal microvasculature and is a leading cause of vision loss globally. Recently, optical coherence tomography angiography (OCTA) has been developed to image the retinal microvasculature, by generating 3-dimensional images based on the motion contrast of circulating blood cells. OCTA offers numerous benefits over traditional fluorescein angiography in visualizing the retinal vasculature in that it is non-invasive and safer; while its depth-resolved ability makes it possible to visualize the finer capillaries of the retinal capillary plexuses and choriocapillaris. High-quality OCTA images have also enabled the visualization of features associated with DR, including microaneurysms and neovascularization and the quantification of alterations in retinal capillary and choriocapillaris, thereby suggesting a promising role for OCTA as an objective technology for accurate DR classification. Of interest is the potential of OCTA to examine the effect of DR on individual retinal layers, and to detect DR even before it is clinically detectable on fundus examination. We will focus the review on the clinical applicability of OCTA derived quantitative metrics that appear to be clinically relevant to the diagnosis, classification, and management of patients with diabetes or DR. Future studies with longitudinal design of multiethnic multicenter populations, as well as the inclusion of pertinent systemic information that may affect vascular changes, will improve our understanding on the benefit of OCTA biomarkers in the detection and progression of DR.

Chorioretinal Anastomosis for Central Retinal Vein Occlusion: A Review of Its Development, Technique, Complications, and Role in Management

Treatments for central retinal vein occlusion (CRVO) have improved dramatically with the advent of intravitreal agents aimed at blocking the effects of the dominant hypoxia-induced upreglulated cytokine, which is vascular endothelial growth factor (VEGF). This cytokine breaks down the capillary endothelial barriers and is a major component of the macular edema in this condition. These treatments although impressive only address some of the sequelae of CRVO and have no effect on the underlying cause which is an obstruction to venous outflow leading to retinal blood flow stagnation and an elevation of the retinal central venous pressure (CVP). The creation of a laser-induced chorioretinal anastomosis (L-CRA) between the obstructed high pressure retinal venous circulation and the unobstructed low pressure choroidal venous circulation is a means addressing the causal pathology. The L-CRA will help lower the elevated CVP, which has been up until now an unaddressed component of the macular edema in this condition.This article reviews the preclinical and clinical development of the L-CRA and the results of the studies into its effect on the natural history of CRVO. It now can be used in combination with existing anti-VEGF treatments with the intravitreal agents addressing the component of the CRVO-induced macular edema due to the cytokine dysregulation, and the L-CRA addressing the component due to the elevated CVP and retinal venous stagnation. Improvements in laser technology have led to higher success rates in L-CRA creation and potential complications are now minimized and better controlled. The combination of L-CRA with intravitreal anti-VEGF agents offers the potential of a permanent cure with a significant reduction in the burden of therapy and improved visual outcomes in this condition.

Retinal Nonperfusion Relationship to Arteries or Veins Observed on Widefield Optical Coherence Tomography Angiography in Diabetic Retinopathy

Purpose

To evaluate whether retinal capillary nonperfusion is found predominantly adjacent to arteries or veins in eyes with diabetic retinopathy (DR).

Methods

Sixty-three eyes from 44 patients with proliferative DR (PDR) or non-PDR (NPDR) were included. Images (12 × 12-mm) foveal-centered optical coherence tomography (OCT) angiography (OCTA) images were taken using the Zeiss Plex Elite 9000. In 37 eyes, widefield montages with five fixation points were also obtained. A semiautomatic algorithm that detects nonperfusion in full-retina OCT slabs was developed, and the percentages of capillary nonperfusion within the total image area were calculated. Retinal arteries and veins were manually traced. Based on the shortest distance, nonperfusion pixels were labeled as either arterial-side or venous-side. Arterial-adjacent and venous-adjacent nonperfusion and the A/V ratio (arterial-adjacent nonperfusion divided by venous-adjacent nonperfusion) were quantified.

Results

Twenty-two eyes with moderate NPDR, 16 eyes with severe NPDR, and 25 eyes with PDR were scanned. Total nonperfusion area in PDR (median: 8.93%) was greater than in moderate NPDR (3.49%, P < 0.01). Arterial-adjacent nonperfusion was greater than venous-adjacent nonperfusion for all stages of DR (P < 0.001). The median A/V ratios were 1.93 in moderate NPDR, 1.84 in severe NPDR, and 1.78 in PDR. The A/V ratio was negatively correlated with the total nonperfusion area (r = −0.600, P < 0.0001). The results from the widefield montages showed similar patterns.

Conclusions

OCTA images with arteries and veins traced allowed us to estimate the nonperfusion distribution. In DR, smaller nonperfusion tends to be arterial-adjacent, while larger nonperfusion tends toward veins.

Optical coherence tomography angiography in diabetic retinopathy: a review of current applications

Background

Diabetic retinopathy (DR) is a leading cause of vision loss in adults. Currently, the standard imaging technique to monitor and prognosticate DR and diabetic maculopathy is dye-based angiography. With the introduction of optical coherence tomography angiography (OCTA), it may serve as a potential rapid, non-invasive imaging modality as an adjunct.

Main text

Recent studies on the role of OCTA in DR include the use of vascular parameters e.g., vessel density, intercapillary spacing, vessel diameter index, length of vessels based on skeletonised OCTA, the total length of vessels, vascular architecture and area of the foveal avascular zone. These quantitative measures may be able to detect changes with the severity and progress of DR for clinical research. OCTA may also serve as a non-invasive imaging method to detect diabetic macula ischemia, which may help predict visual prognosis. However, there are many limitations of OCTA in DR, such as difficulty in segmentation between superficial and deep capillary plexus; and its use in diabetic macula edema where the presence of cystic spaces may affect image results. Future applications of OCTA in the anterior segment include detection of anterior segment ischemia and iris neovascularisation associated with proliferative DR and risk of neovascular glaucoma.

Conclusion

OCTA may potentially serve as a useful non-invasive imaging tool in the diagnosis and monitoring of diabetic retinopathy and maculopathy in the future. Future studies may demonstrate how quantitative OCTA measures may have a role in detecting early retinal changes in patients with diabetes.

[On classification of diabetic retinopathy]

The article analyses current state of the problem of diabetic retinopathy classifications based on the data from Russian and foreign literature on pathogenesis, clinical manifestations, results of multicenter studies on treatment and prognosis of the disease. Every existing classification was found to be limited in applications; attempts had been made to unify and complement them with the aim of achieving more complete and better-detailed description of the processes of diagnostics and determination of treatment algorithms. In conclusion, none of the existing classifications can be considered consistent in both clinical and practical aspects with respect to diabetic retinopathy.