RETINAL LEAKAGE INDEX DYNAMICS ON ULTRA-WIDEFIELD FLUORESCEIN ANGIOGRAPHY IN EYES TREATED WITH INTRAVITREAL AFLIBERCEPT FOR PROLIFERATIVE DIABETIC RETINOPATHY IN THE RECOVERY STUDY

Relationship between ischemic index, leakage index, and macular edema in branch retinal vein occlusion

PURPOSE

To investigate the combined association of the ischemic index and leakage index with macular edema on ultra-widefield fluorescein angiography (UWFFA) in patients with branch retinal vein occlusion (BRVO).

METHODS

Retrospective image analysis study. The leakage index and ischemic index were calculated using Fiji after aligning early and late UWFFA images. Differences in the ischemic index, leakage index, and central macular thickness (CMT) between ischemic and non-ischemic BRVO were compared. Moreover, the association between the ischemic index, leakage index, and macular edema was analyzed.

RESULTS

Eighty-three patients with BRVO were enrolled, including 53 non-ischemic BRVO and 30 ischemic BRVO patients. No significant differences were observed in leakage index and CMT between ischemic BRVO and non-ischemic BRVO (all P > 0.05). In all included patients, CMT correlated with the panretina and all subregion leakage indexes (all P < 0.01), but not with the ischemic index (all P > 0.05). In the ischemic BRVO group, CMT showed a correlation with the leakage index in several regions, but not with the ischemic index. After adjusting for the ischemic index and other clinical features, CMT remained significantly correlated with the leakage index in all regions.

CONCLUSION

The leakage index may be a more effective biomarker for monitoring BRVO-associated macular edema compared to the ischemic index. Further follow-up studies are warranted to validate these findings.

Update on the Management of Diabetic Retinopathy: Anti-VEGF Agents for the Prevention of Complications and Progression of Nonproliferative and Proliferative Retinopathy

Diabetic retinopathy (DR) is a microvascular disease caused by poorly controlled blood glucose, and it is a leading cause of vision loss in people with diabetes. In this review we discuss the current management of DR with particular focus on the use of intraocular anti-vascular endothelial growth factor (anti-VEGF) agents. Intraocular anti-VEGF agents were first studied in the 1990s, and now several of these agents are either FDA approved or used off-label as first-line treatments for DR. Recent evidence shows that anti-VEGF agents can halt the progression of markers of DR severity, reduce the risk of DR worsening, and reduce the onset of new macular edema. These significant benefits have been demonstrated in patients with proliferative DR and the milder nonproliferative DR (NPDR). A wealth of evidence from recent trials and meta-analyses has detailed the intraoperative and postoperative benefits of adjunctive anti-VEGF therapy prior to pars plana vitrectomy (PPV) for proliferative DR with vitreous hemorrhage. In this review, we also discuss literature comparing various anti-VEGF injection regimens including monthly, quarterly, as-needed, and treat and extend protocols. Combination protocols with panretinal photocoagulation (PRP) or PPV are also discussed. Current evidence suggests that anti-VEGF therapies are effective therapy for NPDR and PDR and may also provide significant benefits when used adjunctively with other DR treatment modalities such as PRP or PPV.

Essential Role of Multi-Omics Approaches in the Study of Retinal Vascular Diseases

Retinal vascular disease is a highly prevalent vision-threatening ocular disease in the global population; however, its exact mechanism remains unclear. The expansion of omics technologies has revolutionized a new medical research methodology that combines multiple omics data derived from the same patients to generate multi-dimensional and multi-evidence-supported holistic inferences, providing unprecedented opportunities to elucidate the information flow of complex multi-factorial diseases. In this review, we summarize the applications of multi-omics technology to further elucidate the pathogenesis and complex molecular mechanisms underlying retinal vascular diseases. Moreover, we proposed multi-omics-based biomarker and therapeutic strategy discovery methodologies to optimize clinical and basic medicinal research approaches to retinal vascular diseases. Finally, the opportunities, current challenges, and future prospects of multi-omics analyses in retinal vascular disease studies are discussed in detail.

Computational Imaging Biomarker Correlation with Intraocular Cytokine Expression in Diabetic Macular Edema: Radiomics Insights from the IMAGINE Study

Purpose

Various pathways and cytokines are implicated in pathogenesis of diabetic macular edema (DME). Computational imaging biomarkers (CIBs) of vessel tortuosity from ultra-widefield fluorescein angiography (UWFA) and texture patterns from OCT images have been associated with anti-vascular endothelial growth factor (VEGF) therapy treatment response in DME. This analysis was a radiogenomic assessment of the association between underlying cytokines, UWFA, and OCT-based DME CIBs.

Design

Biclustering analysis based on UWFA and OCT CIBs to identify a common imaging phenotype across patients with subsequent assessment of underlying cytokine signatures and treatment response attributes.

Participants

The IMAGINE DME study was a post hoc study of cytokine expressions that included 24 eyes with sufficient baseline aqueous humor samples and an in-depth assessment of the imaging studies obtained during the phase I/II DmeAntiVEgf study (DAVE) that measured different cytokine expressions.

Methods

A total of 151 graph or morphologic features quantifying leakage shape, size, density, interobject distance, and architecture of leakage spots and 5 vessel tortuosity features were extracted from the baseline UWFA scans, and 494 texture-based radiomics features were extracted from each of the fluid and retinal tissue compartments of OCT images. Biclustering enables simultaneous clustering of patients and features and was used to aggregate patients in terms of their commonality of phenotypes (based on similar imaging attributes) and to identify commonality in terms of cytokine expression and treatment response to anti-VEGF therapy.

Main Outcome Measures

Identification of eyes with similar imaging phenotypes to evaluate commonalities of patterns and underlying cytokine expression.

Results

Strong correlations between VEGF and 7 UWFA leakage morphologic features (Pearson correlation coefficient [PCC], 0.45-0.51; P < 0.05), 1 vascular tortuosity-based UWFA feature (PCC, 0.45; P = 0.00016), and 2 OCT-derived intraretinal fluid texture features (PCC, 0.58-0.63; P < 0.05) were identified. Strong correlation between intraretinal fluid features and other cytokines (PCC, 0.41-0.59; P < 0.05) were also observed.

Conclusions

This study identified groups of eyes with similar imaging phenotypes as defined by UWFA and OCT CIBs that demonstrated similar treatment response patterns and cytokine expression, including a strong association between VEGF with UWFA-derived leakage morphologic and vessel tortuosity features.

Monoclonal antibodies in diabetic retinopathy

INTRODUCTION

Diabetic retinopathy (DR), as one of the main complications of diabetes, is among the leading causes of blindness and visual impairment worldwide.

AREAS COVERED

Current clinical therapies include photocoagulation, vitrectomy, and anti-vascular endothelial growth factor (VEGF) therapies. Bevacizumab and ranibizumab are two monoclonal antibodies (mAbs) inhibiting angiogenesis. Intravitreal ranibizumab and bevacizumab can decrease the rate of blindness and retinal thickness, and improve visual acuity whether as monotherapy or combined with other treatments. They can increase the efficacy of other treatments and decrease their adverse events. Although administered intravitreally, they also might enter the circulation and cause systemic effects. This study is aimed to review our current knowledge about mAbs, bevacizumab and ranibizumab, in DR including superiorities, challenges, and limitations. Meanwhile, we tried to shed light on new ideas to overcome these limitations. Our latest search was done in April 2021 mainly through PubMed and Google Scholar. Relevant clinical studies were imported.

EXPERT OPINION

Future direction includes detection of more therapeutic targets considering other components of DR pathophysiology and shared pathogenesis of DR and neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, the treat-and-extend regimen, and new ways of drug delivery and other routes of ocular drug administration.

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.

The 2-Year Leakage Index and Quantitative Microaneurysm Results of the RECOVERY Study: Quantitative Ultra-Widefield Findings in Proliferative Diabetic Retinopathy Treated with Intravitreal Aflibercept

Eyes with proliferative diabetic retinopathy (PDR) have been shown to improve in the leakage index and microaneurysm (MA) count after intravitreal aflibercept (IAI) treatment. The authors investigated these changes via automatic segmentation on ultra-widefield fluorescein angiography (UWFA). Forty subjects with PDR were randomized to receive either 2 mg IAI every 4 weeks (Arm 1) or every 12 weeks (Arm 2) through Year 1. After Year 1, Arm 1 switched to quarterly IAI and Arm 2 to monthly IAI through Year 2. By Year 2, the Arm 1 leakage index decreased by 43% from Baseline (p = 0.03) but increased by 59% from Year 1 (p = 0.04). Arm 2 decreased by 61% from Baseline (p = 0.008) and by 31% from Year 1 (p = 0.12). Both cohorts exhibited a significant decline in MAs from Baseline to Year 2 (871 to 410; p < 0.001; 776 to 207; p < 0.001, respectively). Subjects with an improved leakage and MA count showed a more significant improvement in the Diabetic Retinopathy Severity Scale (DRSS) score. Moreover, central subfield thickness (CST) was positively associated with changes in the leakage index. In conclusion, the leakage index and MA counts significantly improved from Baseline following IAI treatment, and monthly injections provided a more rapid and sustained reduction in these parameters compared with quarterly injections.

Association of Subregional Quantitative Ultra-widefield Fluorescence Angiography Characteristics With the Occurrence of Diabetic Macular Edema and Proliferative Diabetic Retinopathy

Purpose: To explore the relationships of region-specific properties of ultra-widefield fluorescence angiography (UWFFA) images with two adverse outcomes, diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR), and also the severity of diabetic retinopathy (DR).

Methods: A cross-sectional observational study was performed to retrospectively analyze UWFFA images of patients with DR. All patients underwent UWFFA and optical coherence tomography examination. Leakage index and microaneurysm (MA) count were measured using Trainable Weka Segmentation, a machine learning algorithm, and ischemic index (ISI) was measured manually. The correlation between UWFFA parameters and severity of DR was analyzed, and receiver operating characteristic curves were used to estimate their diagnostic value for DME and PDR.

Results: A total of 108 eyes from 108 patients with DR (mean age of 56.04 ± 8.85 years) were analyzed. As the severity of DR increased, the ISI and leakage index of the panretina and all subregions increased. Panretinal MA count and leakage index were significantly higher in eyes with DME than those without DME (p = 0.044 and 0.001, respectively). Leakage index and ISI were significantly higher in eyes with PDR than those without PDR in both panretinal and subregion-specific measurements (all p < 0.05). Throughout the retina and specifically in the posterior area (PoA), the leakage index had a higher diagnostic value for DME than ISI or MA count (all p < 0.05). The diagnostic value of MA count for PDR was lower than that of ISI and leakage index (all p < 0.05).

Conclusion: The ISI, leakage index, and MA count in the PoA and panretina correlated with the severity of DR, especially the posterior parameter. The leakage index was more valuable than ISI and MA count in determining the occurrence of DME. ISI and leakage index were better predictors of PDR.

The Role of Ultra-Widefield Fundus Imaging and Fluorescein Angiography in Diagnosis and Treatment of Diabetic Retinopathy

PURPOSE OF REVIEW

Early detection and treatment are important for preventing vision loss from diabetic retinopathy. Historically, the gold standard for grading diabetic retinopathy has been based on 7-field 30-degree color fundus photographs that capture roughly the central third of the retina. Our aim was to review recent literature on the role of ultra-widefield (allowing capture of up to 82% of the retina in one frame) fundus imaging in screening, prognostication, and treatment of diabetic retinopathy.

RECENT FINDINGS

Ultra-widefield fundus imaging can capture peripheral retinal lesions outside the traditional 7-field photographs that may correlate with increased risk of diabetic retinopathy progression. The speed and ability to image through undilated pupils make ultra-widefield imaging attractive for tele-ophthalmology screening. Ultra-widefield fluorescein angiography may help guide targeted laser treatment in eyes with proliferative diabetic retinopathy. Ultra-widefield imaging has potential to help shape new diabetic retinopathy screening, staging, and treatment protocols.