Optical coherence tomography angiography characteristics of choroidal neovascularization requiring varied dosing frequencies in treat-and-extend management: An analysis of the AVATAR study

Quantitative Optical Coherence Tomography Detection of New Neovascular Branches and Association With Exudation Recurrence in Neovascular Age-Related Macular Degeneration

Purpose

The purpose of this study was to investigate the clinical role of multi-signal quantitative optical coherence tomography angiography (OCTA) perfusion sampling in neovascular age-related macular degeneration (AMD).

Methods

The study was designed as a cross-sectional case series. We collected data from already treated macular neovascularization (MNV), characterized by (I) clinically relevant recurrent exudation, (II) nonclinically relevant recurrent exudation, and (III) inactive lesion. We proposed a new OCTA metric, calculating the gap between high-resolution (HR) and high-speed (HS) OCTA samplings, hypothesizing that this gap might improve the detection of new secondary MNV branches, being also associated with exudation recurrence. Main outcome measures were the HR-HS gap-based categorization of MNV lesions and the assessment of its association with exudative, minimally exudative, and inactive lesions.

Results

Our cohort (which consisted of 32 MNV eyes; 32 patients; mean disease duration 5 years) was classified as type 1 (17; 53%), type 2 (11; 34%), or mixed type (4; 13%) MNV. Subretinal fibrosis was found in 17 out of 32 eyes (53%), whereas outer retinal atrophy involved 22 of 32 eyes (69%). HR-HS MNV gap was significantly different among MNV subgroups: 18% for the exudative subgroup, 12% for the minimally exudative subgroup, and 4% for the inactive subgroup. HR-HS gap significantly correlated with best corrected visual acuity (BCVA), disease duration, fibrosis, and outer retinal atrophy.

Conclusions

HR-HS gap is a novel quantitative metric to detect the secondary novel branches of AMD-related MNV. This parameter is clinically relevant because it is associated with fluid recurrence. The integration of HR-HS gap in artificial intelligence models might help to predict MNV reactivation and to optimize treatment strategies.

Predictive role of optical coherence tomography angiography for exudation recurrence in patients with type 1 neovascular age-related macular degeneration treated with pro-re-nata protocol

OBJECTIVES

We sought to identify the consecutive changes and predictive features for exudation recurrence in macular neovascularization (MNV) using optical coherence tomography angiography (OCTA) in type 1 neovascular age-related macular degeneration (NVAMD).

METHODS

A total of 291 OCTA images in consecutive visit of 45 patients newly diagnosed with type 1 NMV and treated with three loading intravitreal anti-vascular endothelial growth factor injections (IVIs) and a pro-re-nata (PRN) therapy regimen were analysed. Quantitative features of OCTA included the MNV area, MNV length, total number of endpoints (open-ended vessels) and junctions (internal branching) using AngioTool. Two subgroups were divided according to exudation recurrence time from the third IVI (group 1: ≤3 months vs. group 2: >3 months).

RESULTS

The area, length, number of total junctions, and endpoints decreased during three loading IVIs and increased at exudation recurrence (all p < 0.05). In a subgroup analysis of consecutive OCTA images, the number of total endpoints increased at two months prior to exudate recurrence in group 2 (the late recurrence group, p = 0.020). A higher total number of endpoints of MNV at baseline were found to be related with group 1 (early recurrence, p = 0.020 and 0.012 in univariate and multivariate regression analyses).

CONCLUSIONS

The MNV with higher open-ended vessels at the lesion periphery at baseline might be expected to show earlier recurrence of exudation after loading IVIs. By observing the number of open-ended vessels in consecutive OCTA images, exudation recurrence could be predicted.

Quantitative OCT angiography findings according to pattern classification of type 1 neovascularization exudative age-related macular degeneration

OBJECTIVES

To define neovascularization (NV) patterns and their association with exudative activity in type 1 neovascular age-related macular degeneration (NVAMD).

METHODS

In optical coherence tomography angiography (OCTA) images of type 1 NVAMD, we stratified NV patterns according to whether they contained core vessel (C+/C-) and fine branching vessels (F+/F-) or not into C - F +, C + F +, and C + F - groups. Qualitative analyses assessing the status of peripheral tiny branching, inner branching capillaries, arcade, loop, and perilesional halo and quantitative analyses considering the NV area, length, density, and numbers of junctions and endpoints (open-ended vessels) in NV were conducted according to NV patterns and the presence of exudation on structural OCT.

RESULTS

Among 96 eyes, exudation was found in the C - F + (33.3%) and C + F + (47.6%) groups, related to peripheral tiny branching in both groups (p = 0.022 and p < 0.001) and perilesional halo in the C + F + group (p < 0.001). Peripheral arcades, inner branching capillaries, and loops were observed in more than half (68.3%, 58.7%, and 69.8%) in the C + F + group but not related with exudative activity in the C + F + group. In quantitative analysis, the number of endpoints was associated with exudation in univariate and multivariate analyses (p = 0.011 and p = 0.016) in C + F + group.

CONCLUSIONS

After pattern classification, type 1 NV patterns with fine branching vessels were considered to have exudative activity compared to NV without fine branching. The quantitative analysis of type 1 NV according to patterns showed the presence of peripheral tiny branching vessels was associated with NV activity.

Appearance of Tumor Vessels in Patients With Choroidal Osteoma Using Swept-Source Optical Coherence Tomographic Angiography

Objective

To report the morphologic characteristics of tumor-related vasculatures and their association with secondary choroidal neovascularization (CNV), subretinal fluid (SRF), choroidal thickness, retinal pigment epithelium (RPE) alterations, subretinal hemorrhage, and tumor decalcification in eyes with choroidal osteoma (CO), using swept-source optical coherence tomographic angiography (SS-OCTA).

Design

Cross-sectional observational study.

Participants

We included 26 patients recruited from Beijing Tongren Hospital with a diagnosis of CO, based on the presence of yellow-orange mass deep to the RPE under indirect ophthalmoscopy and occupying the choroid with well-defined margins and bone density on ultrasonography or computed tomography and focal hyperfluorescent spots with no homogeneous pattern on fluorescein angiography/indocyanine green angiography (FA/ICGA). Data were collected from April 1, 2020, to April 1, 2021, and analyzed from April 30 through May 30, 2021.

Methods

Applying SS-OCTA systems operating at 1,050-nm wavelengths, eyes with CO were imaged.

Main Outcome and Measures

Tumor-related vasculature in eyes with CO was characterized using multimodal imaging that included fundus photography, FA/ICGA, SS-OCT, and SS-OCTA, and the images were anatomically aligned. CO thickness was manually measured as the distance between the upper boundary of the tumor and the underlying sclerochoroidal interface on the SS-OCT images. Subfoveal choroidal thickness was manually measured as the distance between the Bruch membrane and the sclerochoroidal interface on the SS-OCT images.

Results

Of the 26 Asian patients, 16 (62%) were women and 10 (38%) were men. The mean age was 26.8 years (median, 23; range, 8–45 years), and the mean best corrected visual acuity (BCVA) was 20/40. Thirty-three eyes underwent imaging and were diagnosed with CO. Indocyanine green angiography identified inhomogeneous hyperfluorescence due to tumor-related vasculature, and all corresponded to the structures that appeared as sea-fan vascular networks (SFVNs) combined with clusters of tangled vessels on SS-OCTA images. SFVNs were detected on SS-OCTA imaging in all eyes (100%), terminal tangled vascular structures in 32 of 33 eyes (97%), but not identified on ICGA. Of the 33 tangled vascular structures, 32 (97%) were located at the edge of or inside the tumor, and only 1 (3%) was associated with type 2 neovascularization. In addition, SS-OCT revealed SRF in 33 eyes (100%), 33 (100%) were located at the edge of CO, and only 1 was underlying macular. SRF with retinal edema was seen in 30 of 32 eyes (94%).

Conclusions

In eyes with CO undergoing SS-OCTA imaging, tumor-related vasculature appears as SFVNs combined with tangled vascular structures or few type 2 neovascularization. The identification of actual tumor vasculature in patients with CO as SFVNs with inner or terminal vascular tangles rather than previously described CNV may help facilitate understanding of their pathogenesis, tumor control, and response to treatment.

Redefining response in wet AMD to anti VEGF therapy based on non-OCTA versus OCTA evaluation

PURPOSE

Anti vascular endothelial growth factor (anti VEGF) has been the mainstay of treatment in wet age-related macular degeneration (AMD). Subsequent decision to continue anti VEGF therapy depends on the treatment response quantified by functional (visual acuity) and morphological (optical coherence tomography) parameters then categorized from good to poor.

METHODS

This study evaluates the agreement between OCT angiography (OCTA) and non-OCTA (logMAR VA plus OCT) to decide anti-VEGF treatment's continuity. After an anti VEGF treatment, on a follow up visit, a patient underwent non-OCTA evaluation (decision A) then OCTA evaluation (decision B) to judge the necessity of future anti VEGF application.

RESULTS

Out of 129 eyes, on 72 eyes (49%), there were agreements on both decision arms, but on 55 eyes (42%) there was disagreement. Particularly, disagreement on 47/55 eyes was important, where OCTA advised "continue anti VEGF" and non-OCTA advised "Stop anti VEGF" therapy. Cohen's Kappa for probability of agreement to continue anti VEGF was fair (0.33) and to stop anti VEGF therapy was none (0.1).

CONCLUSIONS

Based on resulting disagreements between the two modalities on deciding the continuity of anti VEGF, we conclude that OCTA must be considered in the conventional decision making algorithm in patients with wet AMD under anti VEGF therapy.

Quantitative Imaging Biomarkers in Age-Related Macular Degeneration and Diabetic Eye Disease: A Step Closer to Precision Medicine

The management of retinal diseases relies heavily on digital imaging data, including optical coherence tomography (OCT) and fluorescein angiography (FA). Targeted feature extraction and the objective quantification of features provide important opportunities in biomarker discovery, disease burden assessment, and predicting treatment response. Additional important advantages include increased objectivity in interpretation, longitudinal tracking, and ability to incorporate computational models to create automated diagnostic and clinical decision support systems. Advances in computational technology, including deep learning and radiomics, open new doors for developing an imaging phenotype that may provide in-depth personalized disease characterization and enhance opportunities in precision medicine. In this review, we summarize current quantitative and radiomic imaging biomarkers described in the literature for age-related macular degeneration and diabetic eye disease using imaging modalities such as OCT, FA, and OCT angiography (OCTA). Various approaches used to identify and extract these biomarkers that utilize artificial intelligence and deep learning are also summarized in this review. These quantifiable biomarkers and automated approaches have unleashed new frontiers of personalized medicine where treatments are tailored, based on patient-specific longitudinally trackable biomarkers, and response monitoring can be achieved with a high degree of accuracy.

Disease stability and extended dosing under anti-VEGF treatment of exudative age-related macular degeneration (AMD) - a meta-analysis

PURPOSE

To assess disease stability (absence of intra- and/or subretinal fluid) and the portion of eyes being capable to extend their treatment interval to ≥ 12 weeks in exudative age-related macular degeneration (AMD).

METHODS

A systematic literature search was performed in NCBI, PubMed, CENTRAL, and ClinicalTrials.gov to identify clinical studies reporting treatment outcomes for ranibizumab, aflibercept, and brolucizumab in exudative AMD under a treat-and-extend protocol and a follow-up of ≥ 12 months. Weighted mean differences and subgroup comparisons were used to integrate the different studies.

RESULTS

This meta-analysis refers to 29 published series, including 27 independent samples and 5629 patients. In the pooled group, disease stability was reported in 62.9% and 56.0%, respectively, after 12 and 24 months of treatment, whereas treatment intervals were extended to ≥ 12 weeks in 37.7% and 42.6%, respectively. Ranibizumab, aflibercept, and brolucizumab differed regarding their potential to achieve disease stability (56.3%, 64.5%, and 71.5% after 12, and 50.0%, 52.7% and 75.7% after 24 months; p = < 0.001) and to allow an interval extension to ≥ 12 weeks (28.6%, 34.2%, and 53.3% after 12, and 34.2%, 47.7%, and 41.7% after 24 months; p = < 0.001).

CONCLUSION

The portion of eyes achieving disease stability regressed in the second year, whereas the portion of eyes under a ≥ 12-week interval increased. This discrepancy may reflect the challenges in balancing between under-treatment and a reduced treatment burden.

Evaluation of the different thresholding strategies for quantifying choriocapillaris using optical coherence tomography angiography

BACKGROUND

In this paper, we evaluate the different thresholding strategies that have been used for the quantification of the choriocapillaris (CC) and explore their repeatability and the interchangeability of the measurements resulting from its application.

METHODS

Observational study. Eighteen eyes from nine healthy volunteers aged >18 years were imaged four consecutive times with a SD-OCTA system (Heidelberg Engineering, Germany) using a 10°×10° high-resolution protocol centered on the fovea. Projection artifacts were removed, and the CC was bracketed between 10 and 30 µm below Bruch's membrane. For the quantification of CC, we used four flow deficits (FD) parameters: FD number, mean FD size, total FD area and FD density. We performed a systematic review of literature to collect the thresholding methods that have been used for the quantification of CC. The CC quantification parameters were then evaluated after applying each of the thresholding strategies. Intraclass correlation coefficient (ICC) and Pearson's correlation analysis were used to compare the repeatability and interchangeability among the different thresholding strategies for quantifying the CC.

RESULTS

A total of 72 optical coherence tomography angiography (OCTA) examinations were considered. The systematic review allowed us to conclude that three local thresholding strategies (Phansalkar, mean and Niblack) and three global thresholding strategies (mean, default, Otsu) have been used for CC quantification. These strategies were evaluated in our observational study. We found a high agreement within the same method in the quantification of FD number, mean FD size, total FD area and FD density but a poor agreement with different strategies. Local strategies achieved a significantly superior ICC than global ones in CC quantification.

CONCLUSIONS

In conclusion, the interchangeability of the CC quantification using different thresholding strategies is low, and direct comparisons should not be performed. Local thresholding strategies are significantly superior to global ones for quantifying CC and should be preferred. There is an unmet need for a uniform strategy to quantify CC in future studies.

Analysis of the Vascular Morphology of the Fibrotic Choroidal Neovascularization in Neovascular Age-Related Macular Degeneration Using Optical Coherence Tomography Angiography

Purpose Choroidal neovascularization (CNV) in neovascular age-related macular degeneration (nAMD) undergoing anti-VEGF therapy transforms into a fibrotic lesion. This fibrovascular transformation is associated with a great variety of functional and morphological effects. The aim of this study was to investigate the vascular morphology of fibrotic CNV, to compare it with its surrounding tissue and to identify phenotypes using optical coherence tomography angiography (OCTA).

Methods In 18 eyes with fibrotic CNV in nAMD spectral domain OCT (SD-OCT) and OCTA were performed. The automated segmentation lines were manually adjusted. A slab from 60 µm beneath Bruchʼs membrane to the inner edge of the subretinal hyperreflective material was applied. Quantitative analysis of the vascular morphology was performed using skeletonized OCTA images.

Results Compared to the perilesional rim, the number of segments per area was significantly lower (234.75 ± 25.68 vs. 255.30 ± 20.34 1/mm2, p = 0.0003) within the fibrovascular lesion. Two phenotypes could be identified within the lesion. The phenotypic traits of cluster 1 were few, long and thick vascular segments; Cluster 2 was characterized by many, short and thin vascular segments (number of segments per area: 219.4 ± 18.8 vs. 258.8 ± 13.2 1/mm2, p = 0.00009, segment length: 49.6 ± 2.7 vs. 45.0 ± 1.3 µm, p = 0.0002, vascular caliber: 26.6 ± 1.2 vs. 23.5 ± 1.8 µm, p = 0.003). The clusters did not differ significantly regarding visual acuity (0.52 ± 0.44 vs. 0.54 ± 0.18 logMAR, p = 0.25), differentiability of subretinal (OR = 3.43, CI = [0.30, 39.64], p = 0.6) and intraretinal fluid (OR = 5.34, CI = [0.48, 89.85], p = 0.14). Less normalized ellipsoid zone (EZ) loss could be observed in cluster 1 (131.0 ± 161.3 vs. 892.4 ± 955.6 1/m, p = 0.006).

Conclusion In this study the vascular morphology of fibrotic CNV was analyzed using OCTA. Differences between the lesion and a perilesional rim could be detected. Two phenotypes within the fibrovascular lesion were identified. These morphological clusters could indicate different patterns of fibrovascular transformation of the CNV under long-term anti-VEGF therapy and be useful identifying possible predictive biomarkers in future studies.

OCT Angiography Features of Neovascularization as Predictive Factors for Frequent Recurrence in Age-Related Macular Degeneration

PURPOSE

To investigate the features of neovascularization (NV) in eyes with neovascular age-related macular degeneration using optical coherence tomography angiography (OCTA) according to the treatment interval of intravitreal aflibercept injection (IVI).

DESIGN

Retrospective, interventional, comparative case series.

METHODS

Patients with type 1 NV treated with the "pro re nata" regimen after 3 loading IVI were classified into 2 groups based on the numbers of treatments during 12 months, specifically a stable group who required fewer than 2 injections and an unstable group who required more than 3 injections. Quantitative features of OCTA including NV area, NV length, NV density, endpoint density (open-ended vessels per unit length), junction density (vessel junction per unit length), lacunarity, and largest vessel caliber were compared between the 2 groups.

RESULTS

Among 71 eyes, 38 and 33 eyes were classified into the stable and unstable groups, respectively. The unstable group had higher endpoint densities (stable vs unstable: 2.72 vs 3.18; P = .03) and higher levels of lacunarity (0.177 vs 0.211; P = .028). The area, density, length of NV, junction density, and largest vessel caliber were not different between the 2 groups (P = .057, P = .184, P = .062, P = .160, and P = .473, respectively). Endpoint density was correlated with the unstable group in both univariate and multivariate analyses (P = .004, P = .002, respectively). A predictive model with an endpoint index demonstrated a sensitivity of 93.75% and a negative predictive value of 89.47% for the unstable group.

CONCLUSIONS

The characteristics of NV in eyes of exudative age-related macular degeneration with type 1 NV were different according to treatment requirements. Identifying the features of NV on OCTA might be helpful for predicting clinical outcomes and optimal treatment intervals.

Quantitative optical coherence tomography angiography: A review

As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed.

Features and Diagnostic Accuracy of Optical Coherence Tomography Angiography in Neovascular Age-related Macular Degeneration

Introduction Age-related macular degeneration (AMD) is one of the important causes of visual impairment in aging population. Fundus fluorescein angiography (FFA) is gold standard for the diagnosis of neovascular AMD (nAMD) while optical coherence tomography (OCT) aids in the diagnosis of nAMD and is very useful for follow-up. OCT angiography (OCTA) is an evolving imaging technology that can be used as a valid diagnostic tool to study morphology of choroidal neovascularization (CNV) that is seen in nAMD. This study was conducted with the objective to determine diagnostic accuracy and OCTA features of occult and classic CNV in patients with nAMD. Methods In this prospective observational study, 90 eyes of 58 patients with nAMD were studied with OCT, OCTA and FFA. OCTA scans were analyzed to qualitatively describe the morphological appearance of CNV in terms of location, pattern and configuration. The OCTA sensitivity and specificity for CNV detection were calculated by comparing it with FFA. Results FFA detected CNV in 70 of the 90 eyes (77.77%) whereas OCTA identified CNV in 69 eyes (76.7%). Among 69 eyes with CNV, it was well-defined in 51 (73.9%) eyes and poorly defined in 18 (26.1%) eyes. There were four false positive and five false negative cases. The sensitivity, specificity, positive predictive value and negative predictive value of OCTA in detection of nAMD were found to be 92.85%, 80.0%, 94.2 and 76.2, respectively. Conclusion OCTA is a useful, noninvasive, reproducible imaging tool for diagnosing, classifying and localizing CNV. The technique has high sensitivity and specificity and can be used reliably in cases where FFA is contraindicated or inconclusive.