Final Outcomes from the Randomized RECOVERY Trial of Aflibercept for Retinal Nonperfusion in Proliferative Diabetic Retinopathy

Significance of Macrophage-Mediated Inflammatory Response in Ocular Inflammatory Complications

Immune cells such as macrophages play a significant role in ocular inflammation by activating or inhibiting several cellular pathways. Systemic infections and autoimmune diseases could activate macrophages by releasing various pro-inflammatory cytokines, chemokines, and growth factors, which reach the eyes through the blood-retina barrier and cause immune and inflammatory responses. In addition, environmental pollutants, allergens, and eye injuries could also activate macrophages and cause an inflammatory response. Further, the inflammatory response generated by the macrophages could recruit additional immune cells and enhance the inflammatory response. The inflammatory response leads to ocular tissue damage and dysfunction and affects vision. Macrophages are generally implicated in the clearance of pathogens and debris, generate reactive oxygen species, and initiate immune response. However, uncontrolled immune and inflammatory responses could damage the ocular tissues, leading to various ocular inflammatory complications such as uveitis, scleritis, diabetic retinopathy, and retinitis. Recent studies describe the role of individual cytokines in the mediation of specific ocular inflammatory diseases. In this article, we discussed the potential impact of macrophages and their mediated inflammatory response on the development of various ocular inflammatory diseases and possible treatment strategies.

Assessment of Baseline Ultrawidefield Fluorescein Angiographic Quantitative Leakage Parameters with Ultrawidefield Fundus Features and Clinical Parameters in Diabetic Retinopathy in Protocol AA

PURPOSE

Evaluate quantitative leakage parameters on ultrawidefield fluorescein angiography (UWF-FA) images and explore their association with Diabetic Retinopathy Severity Scale (DRSS), predominantly peripheral lesions (PPLs), visual acuity, and clinical characteristics.

DESIGN

A post hoc analysis of baseline UWF-FA images in the DRCR Retina Network observational study Protocol AA.

PARTICIPANTS

A total of 575 eyes from 384 adults across 38 sites in the United States and Canada with gradable UWF-FA.

METHODS

A machine learning-enhanced feature extraction platform provided initial leakage segmentation of UWF-FA images sequentially reviewed and corrected by 2 certified readers for segmentation accuracy. Ultrawidefield fluorescein angiography leakage was measured in 5 retinal zones: panretinal (entire retina), central macular (3-disc diameter fovea-centered circle), posterior pole (6-disc diameter fovea-centered circle), peripheral (outside 6-disc diameter circle), and widefield far peripheral (outside 9-disc diameter circle); associations with clinical factors were evaluated with marginal beta regression models.

MAIN OUTCOME MEASURES

Ultrawidefield fluorescein angiography leakage index, calculated as the area with leakage divided by the analyzable retinal area.

RESULTS

The mean quantitative leakage index was 3.5% for panretinal, 6.6% for macular, 4.8% for posterior pole, 3.3% for peripheral, and 2.8% for widefield far peripheral retinal zones. Panretinal leakage was associated with DRSS (mean 2.2% for no to mild nonproliferative diabetic retinopathy [NPDR], 3.4% for moderate NPDR, 4.2% for moderately severe NPDR, 4.8% for severe NPDR, and 5.1% for proliferative diabetic retinopathy; P < 0.001), hemoglobin A1C (HbA1c) (3.2% for HbA1c < 8% vs. 3.8% for HbA1c ≥ 8%; P = 0.01 for continuous HbA1c), visual acuity (3.3% for 20/25 or better vs. 4.7% for 20/32 or worse; continuous P < 0.001), and UWF-FA-PPL types of intraretinal microvascular abnormality (4.3% vs. 3.3%; P = 0.005) or new vessels elsewhere (5.7% vs. 3.4%; P = 0.003). Diabetic retinopathy severity was also statistically significant for leakage within all retinal zones (P < 0.001); eyes with noncentral diabetic macular edema (DME) versus no DME had higher mean leakage in the central macular (11.2% vs. 5.9%; P = 0.005) and posterior pole regions (9.2% vs. 4.2%; P = 0.002).

CONCLUSIONS

Quantitative UWF-FA leakage analysis identified associations between leakage and DRSS, visual acuity, and presence of DME. In the future, quantitative UWF-FA leakage parameters may be explored as potential biomarkers for disease progression risk.

FINANCIAL DISCLOSURE(S)

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

Wide field imaging biomarkers: A different perspective

Wide field retinal imaging has emerged as a transformative technology over the last few decades, revolutionizing our ability to visualize the intricate landscape of the retina. By capturing expansive retinal areas, these techniques offer a panoramic view going beyond traditional imaging methods. In this review, we explore the significance of retinal imaging-based biomarkers to help diagnose ocular and systemic conditions. We discuss quantitative biomarkers, including ischemic index, nonperfusion area and more, and their application in diabetic retinopathy, central retinal vein occlusion, neurodegenerative diseases, and more. In addition, we outline qualitative biomarkers such as choroidal venous hyperpermeability and intervortex anastomoses. The role of wide field fundus autofluorescence in assessing hereditary retinal diseases is also emphasized. Standardized imaging procedures, professional collaboration, and validation across a range of clinical circumstances are necessary for the effective use of these biomarkers. They have the potential to transform disease identification, risk assessment, and customize therapy.

Heterotypic macrophages/microglia differentially contribute to retinal ischaemia and neovascularisation

AIMS/HYPOTHESIS

Diabetic retinopathy is characterised by neuroinflammation that drives neuronal and vascular degenerative pathology, which in many individuals can lead to retinal ischaemia and neovascularisation. Infiltrating macrophages and activated retina-resident microglia have been implicated in the progression of diabetic retinopathy, although the distinct roles of these immune cells remain ill-defined. Our aim was to clarify the distinct roles of macrophages/microglia in the pathogenesis of proliferative ischaemic retinopathies.

METHODS

Murine oxygen-induced retinopathy is commonly used as a model of ischaemia-induced proliferative diabetic retinopathy (PDR). We evaluated the phenotype macrophages/microglia by immunostaining, quantitative real-time RT-PCR (qRT-PCR), flow cytometry and scRNA-seq analysis. In clinical imaging studies of diabetic retinopathy, we used optical coherence tomography (OCT) and OCT angiography.

RESULTS

Immunostaining, qRT-PCR and flow cytometry showed expression levels of M1-like macrophages/microglia markers (CD80, CD68 and nitric oxide synthase 2) and M2-like macrophages/microglia markers (CD206, CD163 and macrophage scavenger receptor 1) were upregulated in areas of retinal ischaemia and around neo-vessels, respectively. scRNA-seq analysis of the ischaemic retina revealed distinct ischaemia-related clusters of macrophages/microglia that express M1 markers as well as C-C chemokine receptor 2. Inhibition of Rho-kinase (ROCK) suppressed CCL2 expression and reduced CCR2-positive M1-like macrophages/microglia in areas of ischaemia. Furthermore, the area of retinal ischaemia was reduced by suppressing blood macrophage infiltration not only by ROCK inhibitor and monocyte chemoattractant protein-1 antibody but also by GdCl3. Clinical imaging studies of diabetic retinopathy using OCT indicated potential involvement of macrophages/microglia represented by hyperreflective foci in areas of reduced perfusion.

CONCLUSIONS/INTERPRETATION

These results collectively indicated that heterotypic macrophages/microglia differentially contribute to retinal ischaemia and neovascularisation in retinal vascular diseases including diabetic retinopathy. This adds important new information that could provide a basis for a more targeted, cell-specific therapeutic approach to prevent progression to sight-threatening PDR.

Reperfusion of retinal nonperfusion by neovascular-vascular anastomosis in proliferative diabetic retinopathy

BACKGROUND

Retinal nonperfusion is a significant cause of vision loss in patients with proliferative diabetic retinopathy (PDR). Therefore, reperfusion of a nonperfusion has been a matter of strong interest, but few previous studies have demonstrated the potential benefits of reperfusion.

CASE REPORTS

Here, we report longitudinal optical coherence tomography angiographic analysis of two cases of PDR, in which the retinal neovascularization (RNV) that developed in response to retinal ischemia formed anastomoses with pre-existing physiological retinal vessels, resulting in both superficial and deep capillary reperfusion within the nonperfusion. We named this interesting finding "neovascular-vascular anastomosis." Retinal reperfusion due to neovascular-vascular anastomosis differed from recanalization, defined as reperfusion of once-occluded blood vessels, and has not been reported previously.

CONCLUSION

Our observation highlights the potential of RNV to rescue retinal ischemia by the formation of neovascular-vascular anastomoses.

A Literary Pediatric Retina Fellowship With Michael T. Trese, MD

Michael T. Trese, MD (1946-2022), a vitreoretinal surgeon, made significant contributions to the field of retina. Although most known for his work in pediatric retina surgery, he was a pioneer in areas such as medical retina, translational research, and telemedicine. This article reviews his major contributions to spread his knowledge more widely to vitreoretinal trainees and specialists. We discuss six areas where Trese made a lasting impact: lens-sparing vitrectomy, familial exudative vitreoretinopathy, congenital X-linked retinoschisis, autologous plasmin enzyme, regenerative medicine, and telemedicine. [Ophthalmic Surg Lasers Imaging Retina 2023;54:701-712.].

Secretogranin III Selectively Promotes Vascular Leakage in the Deep Vascular Plexus of Diabetic Retinopathy

Diabetic retinopathy (DR), a leading cause of vision loss in working-age adults, induces mosaic patterns of vasculopathy that may be associated with spatial heterogeneity of intraretinal endothelial cells. We recently reported that secretogranin III (Scg3), a neuron-derived angiogenic and vascular leakage factor, selectively binds retinal vessels of diabetic but not healthy mice. Here, we investigated endothelial heterogeneity of three retinal vascular plexuses in DR pathogenesis and the therapeutic implications. Our unique in vivo ligand binding assay detected a 22.7-fold increase in Scg3 binding to retinal vessels of diabetic mice relative to healthy mice. Functional immunohistochemistry revealed that Scg3 predominantly binds to the DR-stressed CD31- deep retinal vascular plexus but not to the relatively healthy CD31+ superficial and intermediate plexuses within the same diabetic retina. In contrast, VEGF bound to healthy and diabetic retinal vessels indiscriminately with low activity. FITC-dextran assays indicated that selectively increased retinal vascular leakage coincides with Scg3 binding in diabetic mice that was independent of VEGF, whereas VEGF-induced leakage did not distinguish between diabetic and healthy mice. Dose-response curves showed that the anti-Scg3 humanized antibody (hAb) and anti-VEGF aflibercept alleviated DR leakage with equivalent efficacies, and that the combination acted synergistically. These findings suggest: (i) the deep plexus is highly sensitive to DR; (ii) Scg3 binding to the DR deep plexus coincides with the loss of CD31 and compromised endothelial junctions; (iii) anti-Scg3 hAb alleviates vascular leakage by selectively targeting the DR-stressed deep plexus within the same diabetic retina; (iv) combined anti-Scg3 and anti-VEGF treatments synergistically ameliorate DR through distinct mechanisms.

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.

Anti-vascular endothelial growth factor for proliferative diabetic retinopathy

BACKGROUND

Proliferative diabetic retinopathy (PDR) is an advanced complication of diabetic retinopathy that can cause blindness. It consists of the presence of new vessels in the retina and vitreous haemorrhage. Although panretinal photocoagulation (PRP) is the treatment of choice for PDR, it has secondary effects that can affect vision. Anti-vascular endothelial growth factor (anti-VEGF), which produces an inhibition of vascular proliferation, could improve the vision of people with PDR.

OBJECTIVES

To assess the effectiveness and safety of anti-VEGFs for PDR and summarise any relevant economic evaluations of their use.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register; 2022, Issue 6); Ovid MEDLINE; Ovid Embase; the ISRCTN registry; ClinicalTrials.gov, and the WHO ICTRP. We did not use any date or language restrictions. We last searched the electronic databases on 1 June 2022.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing anti-VEGFs to another active treatment, sham treatment, or no treatment for people with PDR. We also included studies that assessed the combination of anti-VEGFs with other treatments. We excluded studies that used anti-VEGFs in people undergoing vitrectomy.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies for inclusion, extracted data, and assessed the risk of bias (RoB) for all included trials. We calculated the risk ratio (RR) or the mean difference (MD), and 95% confidence intervals (CI). We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included 15 new studies in this update, bringing the total to 23 RCTs with 1755 participants (2334 eyes). Forty-five per cent of participants were women and 55% were men, with a mean age of 56 years (range 48 to 77 years). The mean glycosylated haemoglobin (Hb1Ac) was 8.45% for the PRP group and 8.25% for people receiving anti-VEGFs alone or in combination. Twelve studies included people with PDR, and participants in 11 studies had high-risk PDR (HRPDR). Twelve studies were of bevacizumab, seven of ranibizumab, one of conbercept, two of pegaptanib, and one of aflibercept. The mean number of participants per RCT was 76 (ranging from 15 to 305). Most studies had an unclear or high RoB, mainly in the blinding of interventions and outcome assessors. A few studies had selective reporting and attrition bias. No study reported loss or gain of 3 or more lines of visual acuity (VA) at 12 months. Anti-VEGFs ± PRP probably increase VA compared with PRP alone (mean difference (MD) -0.08 logMAR, 95% CI -0.12 to -0.04; I2 = 28%; 10 RCTS, 1172 eyes; moderate-certainty evidence). Anti-VEGFs ± PRP may increase regression of new vessels (MD -4.14 mm2, 95% CI -6.84 to -1.43; I2 = 75%; 4 RCTS, 189 eyes; low-certainty evidence) and probably increase a complete regression of new vessels (RR 1.63, 95% CI 1.19 to 2.24; I2 = 46%; 5 RCTS, 405 eyes; moderate-certainty evidence). Anti-VEGFs ± PRP probably reduce vitreous haemorrhage (RR 0.72, 95% CI 0.57 to 0.90; I2 = 0%; 6 RCTS, 1008 eyes; moderate-certainty evidence). Anti-VEGFs ± PRP may reduce the need for vitrectomy compared with eyes that received PRP alone (RR 0.67, 95% CI 0.49 to 0.93; I2 = 43%; 8 RCTs, 1248 eyes; low-certainty evidence). Anti-VEGFs ± PRP may result in little to no difference in the quality of life compared with PRP alone (MD 0.62, 95% CI -3.99 to 5.23; I2 = 0%; 2 RCTs, 382 participants; low-certainty evidence). We do not know if anti-VEGFs ± PRP compared with PRP alone had an impact on adverse events (very low-certainty evidence). We did not find differences in visual acuity in subgroup analyses comparing the type of anti-VEGFs, the severity of the disease (PDR versus HRPDR), time to follow-up (< 12 months versus 12 or more months), and treatment with anti-VEGFs + PRP versus anti-VEGFs alone. The main reasons for downgrading the certainty of evidence included a high RoB, imprecision, and inconsistency of effect estimates.

AUTHORS' CONCLUSIONS

Anti-VEGFs ± PRP compared with PRP alone probably increase visual acuity, but the degree of improvement is not clinically meaningful. Regarding secondary outcomes, anti-VEGFs ± PRP produce a regression of new vessels, reduce vitreous haemorrhage, and may reduce the need for vitrectomy compared with eyes that received PRP alone. We do not know if anti-VEGFs ± PRP have an impact on the incidence of adverse events and they may have little or no effect on patients' quality of life. Carefully designed and conducted clinical trials are required, assessing the optimal schedule of anti-VEGFs alone compared with PRP, and with a longer follow-up.