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

Analyzing Formation and Absorption of Avascular Subretinal Hyperreflective Material in nAMD From OCTA-Based Insights

PURPOSE

To investigate the formation and absorption of avascular subretinal hyperreflective material (avSHRM) in neovascular age-related macular degeneration (nAMD) based on optical coherence tomography angiography (OCTA) characteristics.

DESIGN

Prospective cohort study.

METHODS

This study included patients with treatment-naive nAMD who were followed up for 3 months. Subjects were classified into an avSHRM group and a non-avSHRM group based on the presence of avSHRM at baseline. Quantitative OCTA characteristics including explant area, perimeter, vessel area, density, length, junctions, endpoints, lacunarity, maximum vessel caliber, vessel dispersion, and fractal dimension were assessed, and 3-dimensional volume and optical density ratio (ODR) of avSHRM were measured. Comparison analyses, correlation coefficients, and regression models were applied to explore factors associated with avSHRM formation and absorption.

RESULTS

A total of 88 eyes from 88 patients (39 female) were enrolled. Compared to the non-avSHRM group, the avSHRM group exhibited a more intricate vasculature, characterized by higher values of macular neovascularization (MNV) perimeter, vessel area, total vessel length, total number of junctions, and total number of endpoints (all P < .05), as well as the maximum vessel caliber (P < .001). In the multivariate model, which was adjusted for age, sex, and types of medications, avSHRM absorption was correlated with baseline average vessel length, maximum vessel caliber, and avSHRM ODR (standardized β = 0.274, -0.367, and -0.334; P = .049, .010, and .018, respectively), with an adjusted R² of 0.453.

CONCLUSIONS

Quantitative OCTA measurements can be used for assessing the dynamics of avSHRM in nAMD. Patients with more complex vasculature are at higher risk for avSHRM formation. Average vessel length, maximum vessel diameter, and avSHRM ODR play a role in its absorption.

MORPHOLOGICAL BIOMARKERS PREDICTING EXUDATIVE CONVERSION IN TYPE 1 NONEXUDATIVE MACULAR NEOVASCULARIZATION USING OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To investigate the incidence and morphological biomarkers to predict the exudative conversion in eyes with type 1 nonexudative macular neovascularization using swept-source optical coherence tomography angiography.

METHODS

Macular neovascularizations were detected using the retinal pigment epithelium-to-retinal pigment epithelium-fit slab of swept-source optical coherence tomography angiography scan. Depending on whether exudation developed within a year, the eyes were divided into two groups: active and silent. Qualitative and quantitative optical coherence tomography angiography parameters of the two groups were evaluated to discriminate the biomarkers associated with exudative conversion.

RESULTS

Of the 40 eyes, nine developed exudation within 1 year (incidence rate 22.5%). The active group exhibited a significantly higher "anastomosis and loops" pattern, greater "vessel density," increased "junction density," fewer "number of end points," and lower "lacunarity" compared with the silent group. "Anastomosis and loops" and higher "vessel density" were correlated with the active group in multivariate analyses. A predictive model combining these biomarkers achieved 95% accuracy in predicting exudative conversion.

CONCLUSION

At 12 months, the risk of exudation was 22.5%, and "anastomosis and loops" and "vessel density" were useful optical coherence tomography angiography biomarkers for predicting exudative conversion in eyes with type 1 nonexudative macular neovascularization. For eyes with a high risk of exudative conversion, more frequent follow-up is recommended.

Volume-rendering three-dimensional image analysis of macular neovascularization in age-related macular degeneration

BACKGROUND

To visualize and investigate the three-dimensional (3D) images of macular neovascularization (MNV) in eyes with neovascular age-related macular degeneration using optical coherence tomography angiography (OCTA) according to the treatment response to intravitreal aflibercept injection (IVI).

METHODS

OCTA images at baseline and 12 weeks (after three loading IVIs) were retrospectively reconstructed as 3D images for patients with type 1 and 2 MNV treated with the "pro-re-nata" regimen. The fluid-free and persistent fluid groups were divided according to the presence of subretinal and intraretinal fluid at 12 weeks after treatment. Using reconstructed 3D images of MNV, the volume, average volume per slice, and z-axis of the volumetric structure were evaluated.

RESULTS

Twenty-three and nine were classified into the fluid-free and persistent fluid groups, respectively. The MNV volume decreased significantly from baseline to 12 weeks in the fluid-free group (p = 0.005), not in the persistent fluid group (p = 0.250). The average volume of MNV per slice at 12 weeks correlated with the persistent fluid group in both the univariate and multivariate analyses (p = 0.034, p = 0.039, Exp [B] = 14.005).

CONCLUSIONS

This study may provide a perspective on vascular volumetric changes of MNV according to treatment response.

Non-invasive quantification of corneal vascularization using anterior segment optical coherence tomography angiography

The presence of corneal vascularization (CV) interferes with the angiogenic and immune privilege of the cornea, risking rejection in eyes following keratoplasty. Pre-operative (lymph)-angioregression is a promising therapeutic approach, but objective monitoring by non-invasive CV imaging is needed. The purpose of this study was to investigate anterior-segment optical coherence tomography angiography (AS-OCTA) for CV visualization and quantification, and to show its superiority over slit-lamp photography in high-risk eyes scheduled for keratoplasty. This institutional pilot study included 29 eyes of 26 patients (51 ± 16 years, 8 female) with significant CV scheduled for keratoplasty that were imaged by slit-lamp photography (Zeiss SL 800) and AS-OCTA (Zeiss Plex Elite 9000). After manual corneal layer segmentation correction, CV maximum/relative depth was measured with the inbuilt software. Slit-lamp photographs and AS-OCTA images were compared for visualization of vascular details. Angiotool software allowed a semi-automated determination of CV-related parameters in the vascular complex of AS-OCTA images. The predominant causes of CV were the herpes simplex virus keratitis (n = 7) and chemical burn (n = 4). Visualization of vascular morphology in AS-OCTA was superior to slit-lamp photography in all except one eye. Vascular metrics including total vessel length, number of junctions/endpoints, junction density, lacunarity, and vessel area/density were defined using Angiotool, with CV depth localization despite scarring and opacification. AS-OCTA proved effective for angioregressive treatment monitoring. AS-OCTA enables non-invasive and objective three-dimensional visualization of corneal vascularization superior to slit-lamp photography, and could be a precious tool for monitoring angioregressive preconditioning prior to keratoplasty.

Pachychoroid neovasculopathy versus macular neovascularization in age-related macular degeneration with and without shallow irregular pigment epithelial detachment

To compare the choroidal neovascular features of individuals with pachychoroid neovasculopathy (PNV) and neovascular age-related macular degeneration (nAMD) with and without shallow irregular pigment epithelial detachment (SIPED). Using optical coherence tomography angiography, the choroidal neovascular complexes of 27 patients with PNV, 34 patients with nAMD and SIPED, and 15 patients with nAMD without SIPED were analyzed with FIJI and AngioTool software. PNV compared to nAMD with SIPED had a greater vessel percentage area (P = 0.034), junction density (P = 0.045), average vessel length (P < 0.001), and fractal dimension (P < 0.001). PNV, compared to nAMD without SIPED, had a greater total vessel length (P = 0.002), total number of junctions (P < 0.001), junction density (P = 0.034), and fractal dimension (P = 0.005). nAMD with SIPED, compared to nAMD without SIPED, had greater vessel area, total number of junctions, total vessel length, and average vessel length (all P values < 0.001). Patients with nAMD plus SIPED and individuals with nAMD without SIPED have similar fractal dimension values (P = 0.703). Biomarkers of choroidal neovascular complexity, such as fractal dimension, can be used to differentiate PNV from nAMD with or without SIPED.

PREDICTIVE ROLES OF QUANTITATIVE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FEATURES IN PROGNOSIS OF MYOPIC CHOROIDAL NEOVASCULARIZATION

PURPOSE

To explore the predictive roles of the morphologic features of neovascularization in the prognosis of myopic choroidal neovascularization.

METHODS

In this retrospective case series study, quantitative morphologic features of neovascularization were obtained from the optical coherence tomography angiography images. According to the number of anti-vascular endothelial growth factor injections administered within 1 year, the eyes were classified into a stable group (≤2 injections) or an unstable group (>2 injections). Best-corrected visual acuity was recorded before the treatment and at the 1-year follow-up.

RESULTS

Overall, 50 eyes with treatment-naive myopic choroidal neovascularization were included; 26 in the stable group and 24 in the unstable group. Multivariate analysis showed that the eyes in the unstable group were associated with a larger lesion area (odds ratio = 2.596, P = 0.012), higher junction density (odds ratio = 1.611, P = 0.014), and higher end point density (odds ratio = 1.435, P = 0.023).The area under the receiver operating characteristic curve of the multivariate model was 0.865, with 91.7% sensitivity and 65.4% specificity. The final best-corrected visual acuity was significantly correlated with the lesion area (β = 0.152, P = 0.032) after adjusted for age, sex, and baseline best-corrected visual acuity.

CONCLUSION

Lesions with larger areas and higher end point and junction densities tended to have more frequent anti-vascular endothelial growth factor injections and worse visual outcomes in eyes with myopic choroidal neovascularization.

Growth of nonexudative macular neovascularization in age-related macular degeneration: an indicator of biological lesion activity

PURPOSE

To investigate the growth of nonexudative macular neovascularization (MNV) in age-related macular degeneration (AMD) using swept-source optical coherence tomography angiography (SS-OCTA).

METHODS

Patients with treatment-naïve nonexudative AMD in one eye and exudative AMD in the fellow eye who underwent SS-OCTA imaging for at least 12 months were retrospectively reviewed. The MNV area measurement was quantified in eyes with treatment-naïve nonexudative MNV using ImageJ for analysing the correlation between MNV growth and the onset of exudation, as well as evaluating the consistency of the MNV growth rate during the subclinical and exudative stages. Kaplan-Meier survival analysis and logistic regression analyses were used.

RESULTS

In total, 45 eyes with treatment-naïve nonexudative AMD from 45 patients were enrolled. Treatment-naïve nonexudative MNV was identified in 21 eyes (46.67%) at baseline. The development of exudative findings was noted in eight eyes (17.78%), including six eyes with previously noted nonexudative MNV. Eyes with growing MNV (increase in area ≥50% within 12 months) had an increased risk of exudation and developed exudation earlier than eyes with stable MNV (13.60 [6.43-20.77] months versus 31.11 [26.61-35.62] months, P < 0.0001, Log-rank test). Consistent growth pattern of MNV lesions was further identified in eyes with growing MNV during anti-VEGF treatment.

CONCLUSION

SS-OCTA allows to qualitatively and quantitatively evaluate nonexudative MNV in AMD patients. Growing MNV involved higher probabilities and a faster onset of exudation compared to stable MNV. Identifying the growth of MNV on OCTA might be helpful for establishing treatment strategies and follow-up planning.

QUANTIFIED ANASTOMOTIC AREAS OF NEOVASCULARIZATION AS FACTORS ASSOCIATED WITH FREQUENT RECURRENCE IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

To investigate the quantitative characteristics of anastomoses of macular neovascularization (MNV) in neovascular age-related macular degeneration using optical coherence tomography angiography according to the frequency of intravitreal injections.

METHODS

Eighty-six eyes of 86 patients treated for neovascular age-related macular degeneration were classified into two groups based on the number of intravitreal injections administered over 12 months: stable (<3) and unstable (≥3). Anastomotic areas were defined as areas surrounded by neighboring vessels in the MNV; their total number, mean area, maximal and minimal diameters (i.e., maximal and minimum Feret diameters), and ratio (Feret aspect ratio) were analyzed in the inner and outer areas of the MNV.

RESULTS

Forty-four and 42 eyes were classified into the stable and unstable groups, respectively. The eyes in the unstable group had larger anastomotic areas with longer minimum Feret diameters and longer perimeters in the outer MNV. In the logistic regression analysis, instability was associated with a larger anastomotic area and a longer minimum Feret diameter in the outer MNV. Multivariate analysis revealed that a longer minimum Feret diameter in the outer MNV was the most significant factor ( P = 0.03).

CONCLUSION

The quantitative characteristics of the anastomotic areas in the MNV might indicate the need for intravitreal injections in patients with neovascular age-related macular degeneration.

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.

Morphology of en face Haller vessel and macular neovascularization at baseline and 3 months as predictive factors in age-related macular degeneration

The clinical implication of en face imaging of Haller vessels and macular neovascularization (MNV) in neovascular age-related macular degeneration (nAMD) is not well established. The purpose of this study is to investigate whether the early-phase morphology of en face Haller vessel and MNV is related to the injection frequency and visual outcome in treatment-naïve nAMD. En face images of Haller vessel and MNV were acquired from 52 eyes at baseline, after three loading doses and at 12 months later using optical coherence tomography (OCT) and OCT angiography. Vessel area, diameter, length, intersection number, fractal dimension, and lacunarity were calculated. Patients were classified according to the injection frequency (< 5 as the infrequent group) and visual gain (≥ 0.3 logMAR) over 12 months. The infrequent group was associated with a longer Haller vessel length after loading doses (OR 3.05, P = 0.01), while visual gain was associated with a smaller maximal MNV diameter after loading doses (OR 0.22, P = 0.03). A predictive model for frequent injection based on the Haller vessel length demonstrated an AUC of 0.71. In conclusion, the en face Haller vessel and MNV morphology after loading doses can be used as biomarkers for the injection frequency and visual gain during the first year in treatment-naïve nAMD patients.

Predicting lesion shrinkage in eyes with myopic choroidal neovascularization from features on optical coherence tomography angiography

PURPOSE

To identify baseline morphological predictors of lesion shrinkage in eyes with myopic choroidal neovascularization (mCNV) treated with anti-vascular endothelial growth factor (VEGF).

METHODS

This retrospective study included 46 eyes (41 consecutive patients) with active mCNV receiving anti-VEGF treatment. Optical coherence tomography angiography (OCTA) was performed at baseline and 1 year after treatment. Quantitative features were obtained from OCTA images using AngioTool software. Eyes were classified as "high-shrinkage" or "low-shrinkage" according to the median relative change in lesion area. Baseline quantitative morphological features associated with mCNV shrinkage were identified in univariate and multivariate analyses.

RESULTS

The mCNV area was significantly smaller after 1 year (P=0.013), with a median relative change of -16.5%. The relative change in mCNV area was -48.3% in high-shrinkage eyes (n=23) and -5.2% in low-shrinkage eyes (n=23). High-shrinkage eyes had a smaller mCNV area (P=0.013), shorter total vessel length (P=0.023), and higher endpoint density (P<0.001). Multivariate analysis showed significant associations of high shrinkage with endpoint density (β=-0.037, P=0.043) and previous anti-VEGF treatment (β=0.216, P=0.029).

CONCLUSION

Morphological features of neovascularization detected by OCTA can predict lesion shrinkage in eyes with mCNV receiving anti-VEGF therapy. Higher endpoint density contributed to shrinkage, particularly of treatment-naive lesions.

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.

Baseline predictors for subretinal fibrosis in neovascular age-related macular degeneration

To find baseline predictors for subretinal fibrosis (SF) in neovascular age-related macular degeneration (nAMD). Forty-five eyes of 45 participants with treatment-naïve nAMD were consecutively enrolled and treated according to a standardized treat-and-extend protocol. Spectral-domain optical coherence tomography (OCT), color fundus photography and fluorescein angiography as well as novel imaging modalities polarization-sensitive OCT and OCT angiography (OCTA) were performed to detect SF after 1 year and find baseline predictors for SF development. Baseline OCTA scans were evaluated for quantitative features such as lesion area, vessel area, vessel junctions, vessel length, vessel endpoints and mean lacunarity. Additionally, the type of macular neovascularization, the presence of subretinal fluid, intraretinal fluid (IRF), subretinal hyperreflective material (SHRM), retinal hemorrhage as well as best-corrected visual acuity (BCVA) were evaluated. After 12 months 8 eyes (18%) developed SF. Eyes with SF had worse baseline BCVA (p = .001) and a higher prevalence of IRF (p = .014) and SHRM at baseline (p = .017). There was no significant difference in any of the evaluated quantitative OCTA parameters (p > .05) between eyes with and without SF. There were no quantitative baseline microvascular predictors for SF in our study. Low baseline BCVA, the presence of IRF and SHRM, however, are easily identifiable baseline parameters indicating increased risk.

Morphologic and Microvascular Differences Between Macular Neovascularization With and Without Subretinal Fibrosis

Purpose

To evaluate morphologic and microvascular differences between eyes with and without subretinal fibrosis (SF) caused by neovascular age-related macular degeneration (nAMD).

Methods

Patients with nAMD with a minimum history of 12 months of anti-VEGF treatment were prospectively included in this cross-sectional study. Patients were imaged using standard imaging, swept-source optical coherence tomography angiography for quantitative microvascular analysis and polarization-sensitive OCT as an ancillary method for automated SF segmentation. The presence of reticular pseudodrusen, hyperreflective foci (HRF), and outer retinal tubulation (ORT) were also evaluated.

Results

Sixty eyes of 60 participants (37 female) with nAMD and a mean 3.1 (±2.7)-year history of anti-VEGF treatment were included, 20 (33%) of which were diagnosed with SF. Eyes with SF had a higher prevalence of ORT (P < 0.001) and a lower prevalence of HRF (P = 0.004) than eyes without SF. Fifty eyes were analyzed quantitatively for microvascular biomarkers. Eyes with SF had a larger greatest vascular caliber (P = 0.001) and greatest linear diameter (P = 0.042), a larger microvascular neovascularization (MNV) area (P = 0.026), larger vessel area (P = 0.037), higher number of vessel junctions (P = 0.025), longer total vessel length (P = 0.027), higher number of vessel endpoints (P = 0.007), and higher endpoint density (P = 0.047).

Conclusions

This multimodal imaging approach demonstrated in vivo microvascular and morphological differences in eyes with and without SF. Eyes with SF tend to have larger MNV lesions with thicker vessels and are often associated with the presence of ORT.

Translational Relevance

This study points out imaging biomarkers in patients with SF, which may help identifying high-risk patients.

Five-Year Reactivation After Ranibizumab or Aflibercept Treatment for Neovascular Age-Related Macular Degeneration and Polypoidal Choroidal Vasculopathy

Purpose: To evaluate 5-year reactivation after ranibizumab or aflibercept treatment for neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV). Methods: This retrospective study included 192 patients (192 eyes) who had been diagnosed with neovascular AMD or PCV and treated with ranibizumab or aflibercept. The incidence and timing of lesion reactivation during the 5-year follow-up period were evaluated, and the factors associated with reactivation were also investigated. Results: During the follow-up period, lesion reactivation was noted in 156 patients (81.3%) at a mean of 9.5 ± 10.5 months after the third antivascular endothelial growth factor injection. The incidence of reactivation was 59.9% during the first 12 months, 33.7% during ≥12 and <24 months, 11.8% during >24 and ≤36 months, 15.5% during >36 and ≤48 months, and 5.3% during >48 and ≤60 months. There was a significant difference in the incidence among the 5 periods (P < 0.001). The proportion of PCV was significantly higher in patients experiencing reactivation (51.9%) than in those who did not (30.6%) (P = 0.021). Conclusions: During the 5-year follow-up, lesion reactivation was noted in approximately four-fifths of the patients. The incidence of lesion reactivation was highest during the first 12 months and decreased thereafter. The incidence was higher in patients with PCV than in those with neovascular AMD, especially after 12 months.

Nonexudative morphologic changes of neovascularization on optical coherence tomography angiography as predictive factors for exudative recurrence in age-related macular degeneration

PURPOSE

To evaluate morphologic changes of choroidal neovascularization (CNV) on optical coherence tomography angiography (OCTA) during the nonexudative period and to correlate the features and timing of recurrence in neovascular age-related macular degeneration. (AMD).

METHODS

Two hundred thirty-eight eyes with type 1 CNV were retrospectively reviewed. For cases with exudative recurrence, OCTA images were tracked for analysis between the recurrences. Qualitative parameters of morphologic changes of CNV on OCTA, including tiny branching vessels, anastomotic loops, peripheral vascular arcade, and perilesional halo, were correlated with the features of exudative recurrence.

RESULTS

Exudative recurrence was identified in 163 cases, and among them, nonexudative morphological changes in CNV were identified using OCTA in 45 cases. For the cases with nonexudative changes on OCTA, exudative recurrence eventually developed within 0.5-3.5 months (mean, 2.3 ± 2.0 months) after identifying morphologic changes OCTA. The following changes in CNV were revealed on OCTA: tiny branching vessels in 53.3% (24/45) of cases, anastomotic loops in 40.0% (18/45), peripheral vascular arcades in 44.4% (20/45), and perilesional halo in 35.6% (16/45). Among the morphologic parameters, development of tiny branching vessels was significantly associated with early exudative recurrence (1.5 ± 1.2 months, p = 0.019), higher incidence of intraretinal fluid (IRF) (p = 0.016), and subretinal or subretinal pigment epithelial hemorrhage (p = 0.023) at recurrence, compared with other morphologic changes.

CONCLUSION

Development of tiny branching vessels of CNV on OCTA during the nonexudative period was associated with early exudative recurrence, including IRF or hemorrhage. Identifying the nonexudative changes of CNV on OCTA might predict exudative recurrence and provide additional parameters for monitoring neovascular AMD.

Choroidal Neovascularization and Haller Vessel Morphology Associated with Vision and Treatment Number after 1 year in Age-related Macular Degeneration

Purpose

The present study aimed to quantify various factors of vessel morphology, including vessel diameter, length, and complexity (fractal dimension and lacunarity) of both choroidal neovascularization (CNV) and en face Haller vessels using optical coherence tomography angiography (OCTA) and en face structural optical coherence tomography in typical neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV) and to identify factors associated with visual acuity (VA) loss and number of injections within a year after the day of OCTA.

Methods

We retrospectively analyzed 43 eyes of nAMD patients and 33 eyes of PCV patients whose OCTA was performed at least 12 months after an initial anti-vascular endothelial growth factor treatment. Quantitative parameters, including vessel area, vessel diameter, vessel length, fractal dimension, and lacunarity were analyzed from en face images of CNV and Haller vessels. Clinical information, including logarithm of the minimum angle of resolution visual acuity and injection number of anti-vascular endothelial growth factor were acquired after 12 months from OCTA date. Using logistic regression analyses, parameters associated with logarithm of the minimum angle of resolution VA loss of 0.2 or more (VA loss group) and a number of injections of four or more (unstable group) after 12 months were analyzed.

Results

In typical nAMD, the VA loss group was associated with a smaller number of intersections of Haller vessels. The unstable group was associated with an increased lacunarity of CNV in typical nAMD. In PCV, both VA loss and unstable groups were associated with a higher maximal diameter of Haller vessels.

Conclusions

VA loss and injection number of nAMD and PCV 12 months after OCTA imaging were associated with different morphological parameters of CNV and Haller vessels. Therefore, quantitative analyses of both CNV and Haller vessels from OCTA and en face optical coherence tomography might provide prognostic information about visual outcome and injection frequency within 12 months after OCTA imaging.

Different effects of anti-VEGF drugs (Ranibizumab, Aflibercept, Conbercept) on autophagy and its effect on neovascularization in RF/6A cells

INTRODUCTION

Choroidal neovascularization (CNV) is the main pathological change of wet age-related macular degeneration. Anti-VEGF drugs are the most commonly used treatment for CNV. The biggest drawback of anti-VEGF drugs is the recurrence of CNV, which requires repeated therapy several times. Autophagy activation may be involved in reducing the therapeutic effect of anti-VEGF drugs. So, this study aims to elucidate the effect and mechanism of anti-VEGF drugs on endothelial autophagy and neovascularization in vitro.

METHODS

RF/6A cells were randomly divided into five groups: The control group, hypoxia group (1% O₂, 5% CO₂, 94% N₂), anti-VEGF group (group1: Ranibizumab 100 μg/ml; group2: Aflibercept, 400 μg/ml; group3: Conbercept, 100 μg/ml). Autophagy-related proteins were examined by Western blot. RFP-GFP-LC3 was used to detect autophagy and autophagic flow. Subsequently, we used autophagy inhibitors (3-MA or CQ) to inhibit Conbercept induced autophagy and to observe its effect on angiogenesis in vitro. Proliferation, migration, and tube formation of endothelial cells can be used to study neovascularization in vitro. In this research, the CCK-8 assay was used to detect cell proliferation. Cell migration and tube formation were assessed by wound assay and matrix method, respectively. Flow cytometry and Tunel were used to detect cell apoptosis. Finally, the mechanism of Conbercept activated autophagy was studied. Western blot was used to detect the expression of p53 and DRAM (damage-regulated autophagy modulator), upstream activators of autophagy.

RESULTS

The protein levels of Beclin-1 and LC3-2/1 in Ranibizumab and Conbercept groups were significantly higher than in the hypoxia group(P < 0.05). While the expression of P62 was decreased (P < 0.05). The autophagic flux was showed the same results. However, Aflibercept showed the opposite effect on autophagy. Compared with the Conbercept group, autophagy inhibitor 3-MA or CQ can further inhibit cell proliferation and promotes cell apoptosis (P < 0.05). Conbercept significantly inhibited cell migration compared with the hypoxia group (633.08 ± 72.52 vs. 546.33 ± 24.61), while the autophagy inhibitor group (3-MA or CQ) had a more obvious inhibition effect (309.75 ± 86.36 and 263.33 ± 68.67) (P < 0.05). For tube formation, the number of tube formation was decreased significantly in the Conbercept group (32.00 ± 2.00) compared to the hypoxia group (39.00 ± 1.53) and even further reduced in 3-MA or CQ group (24.00 ± 3.61, 20.00 ± 2.65). The length of master segments in the hypoxia group was 15,668.00 ± 894.11. It was decreased in Conbercept (13,885.34 ± 730.03). In 3-MA or CQ group, the length of master segments dropped further (11,997.00 ± 433.66, 10,617.67 ± 543.21). Compare with the hypoxia group, the expression P53 and DRAM were increased in the Conbercept group (P < 0.05). Autophagy-related proteins LC-3, Beclin-1, and DRAM were inhibited by P53 inhibitor Pifithrin-α (PFTα) (P < 0.05).

CONCLUSION

Ranibizumab and Conbercept can trigger the autophagy of vascular endothelial cells while Aflibercept can inhibit it. The combination of Conbercept and autophagy inhibitor can significantly inhibit the formation of angiogenesis in vitro. The mechanism of autophagy activation is related to the activation of the p53/DRAM pathway.

Optical Coherence Tomography Angiography-Based Quantitative Assessment of Morphologic Changes in Active Myopic Choroidal Neovascularization During Anti-vascular Endothelial Growth Factor Therapy

Purpose: To establish quantitative profile of the morphologic changes among patients with active myopic choroidal neovascularization (mCNV) before and after anti-vascular endothelial growth factor (VEGF) therapy using optical coherence tomography angiography (OCTA) to assess the therapeutic response.

Methods: Patients with active mCNV who received anti-VEGF injections between February 2017 to October 2020 and fit the study criteria were retrospectively reviewed. Quantitative analysis of their OCTA images were carried out to evaluate the morphologic features and vascular changes of mCNV lesions in response to anti-VEGF therapy. For further quantitative profiling, mCNV area, fractal dimension, vessel area, vessel density, vessel diameter, vessel length, vessel junction, junction density, and vessel tortuosity were obtained by means of advanced skeletonization postprocessing analyses.

Results: Thirty-one eyes of 29 consecutive patients with OCTA-positive mCNV lesions (mean spherical equivalent: −12.55 ± 3.24 diopters) were included. The 31 cases were divided into two phenotypes at baseline: organized interlacing pattern (83.87%) and disorganized vascular loops pattern (16.13%). The values of mCNV area, fractal dimension, vessel area, vessel length, vessel junction, and junction density decreased remarkably 1 month after the initial anti-VEGF injection (p < 0.001). Although, vessel density, vessel diameter, and vessel tortuosity increased meanwhile, only vessel diameter displayed statistical significance (p = 0.027). Of note, relative ratio analysis showed that vessel junction was the most sensitive biomarker in response to anti-VEGF therapy, reflecting a mean decrease of 50.36%. Sensitivity lowered successively in biomarkers of vessel length, vessel area, junction density, mCNV area, and fractal dimension. In addition, percent change of mCNV area (r = 0.552, p = 0.002), fractal dimension (r = 0.446, p = 0.017), vessel area (r = 0.518, p = 0.005), and vessel length (r = 0.440, p = 0.019) were moderately associated with that of central retinal thickness.

Conclusions: The study showed morphological as well as quantitative changes on OCTA responding to anti-VEGF treatment in mCNV patients, among which vessel junctions might be the most predictive biomarker. OCTA-based analysis, providing intuitive images and a large spectrum of quantitative data at the same time, could promote new insights into the therapeutic response assessment in mCNV patients.

A proof of concept study to evaluate the treatment response of aflibercept in wARMD using OCT-A (Canada study)

PURPOSE

To Utilize OCT-A to measure the change in size (mm²) and density (flow index) of choroidal neovascular membranes (CNVMs) from baseline to week 52 of treatment-naïve wet age-related macular degeneration (wARMD) patients receiving intravitreal aflibercept injections (IAI).

METHODS

Patients were treated with IAI at baseline, month 1 and month 2 and then every other month for a total of 12 months. Along with clinical examination and best corrected visual acuity (BCVA), OCT-A 6- and 3-mm scans were acquired at every visit between May 2017 and January 2019. Data from baseline, week 12 and week 52 were analyzed prospectively and included in the final analysis.

RESULTS

Twenty-five eyes from 23 patients were included in the study. The mean BCVA at baseline and week 52 increased from 20/125 to 20/80, respectively (p < 0.001). The mean CST at baseline and week 52 decreased from 330.48 to 222.40 μm, respectively (p < 0.001). 1Seventeen patients (18 eyes) completed all protocol-based 6 × 6 mm and 3 × 3 mm OCT-A scans. In this subgroup, 6-mm OCT-A scans revealed that the mean size of the CNVM before and after IAI was 1.21 mm² and 0.56 mm², respectively (p < 0.001), while the 3-mm OCT-A scans at baseline and week 52 demonstrated a decrease in mean size of the CNVM from 0.89 to 0.37 mm², respectively (p < 0.001). The 6-mm perfusion density map revealed no difference at either time points.

CONCLUSIONS

OCT-A provides a useful approach for monitoring and evaluating the treatment of intravitreal aflibercept for CNVMs. Mean size of CNVMs can be identified by 3- or 6-mm scans, but without machine learning, it requires extensive segmentation. While reproducibility and clear delineation of CNVMs in wARMD using OCT-A is challenging, OCT-A does offer the ability to monitor CNVM size changes during treatment and may offer another biomarker to assist in assessing treatment response.

A quantitative comparison of four optical coherence tomography angiography devices in healthy eyes

PURPOSE

Optical coherence tomography angiography (OCT-A) is a novel imaging modality for the diagnosis of chorioretinal diseases. A number of FDA-approved OCT-A devices are currently commercially available, each with unique algorithms and scanning protocols. Although several published studies have compared different combinations of OCT-A machines, there is a lack of agreement on the consistency of measurements across OCT-A devices. Therefore, we conducted a prospective quantitative comparison of four available OCT-A platforms.

METHODS

Subjects were scanned on four devices: Optovue RTVue-XR, Heidelberg Spectralis OCT2 module, Zeiss Plex Elite 9000 Swept-Source OCT, and Topcon DRI-OCT Triton Swept-Source OCT. 3 mm × 3 mm images were utilized for analysis. Foveal avascular zone (FAZ) area was separately and independently measured by two investigators. Fractal dimension (FD), superficial capillary plexus (SCP), and deep capillary plexus (DCP) vessel densities (VD) were calculated from binarized images using the Fiji image processing software. SCP and DCP VD were further calculated after images were skeletonized. Repeated measures ANOVA, post hoc tests, and interclass correlation coefficient (ICC) were performed for statistical analysis.

RESULTS

Sixteen healthy eyes from sixteen patients were scanned on the four devices. Images of five eyes from the Triton device were excluded due to poor image quality; thus, the authors performed two sets comparisons, one with and one without the Triton machine. FAZ area showed no significant difference across devices with an ICC of > 95%. However, there were statistically significant differences for SCP and DCP VD both before and after skeletonization (p < 0.05). Fractal analysis revealed no significant difference of FD at the SCP; however, a statistically significant difference was found for FD at the DCP layer (p < 0.05).

CONCLUSIONS

The results showed that FAZ measurements were consistent across all four devices, while significant differences in VD and FD measurements existed. Therefore, we suggest that for both clinical follow-up and research studies, FAZ area is a useful parameter for OCT-A image analysis when measurements are made on different machines, while VD and FD show significant variability when measured across devices.