Enhancing Diabetic Macular Edema Treatment Outcomes: Exploring the ESASO Classification and Structural OCT Biomarkers.

INTRODUCTION: This study assessed the European School of Advanced Studies in Ophthalmology (ESASO) classification's prognostic value for diabetic macular edema (DME) in predicting intravitreal therapy outcomes. METHODS: In this retrospective, multicenter study, patients aged > 50 years with type 1 or 2 diabetes and DME received intravitreal antivascular endothelial growth factor (anti-VEGF) agents (ranibizumab, bevacizumab, and aflibercept) or steroids (dexamethasone). The primary outcome was visual acuity (VA) change post-treatment, termed as functional response, measured 4-6 weeks post-third anti-VEGF or 12-16 weeks post-steroid injection, stratified by initial DME stage. RESULTS: Of the 560 eyes studied (62% male, mean age 66.7 years), 31% were classified as stage 1 (early), 50% stage 2 (advanced), 17% stage 3 (severe), and 2% stage 4 (atrophic). Visual acuity (VA; decimal) improved by 0.12-0.15 decimals in stages 1-2 but only 0.03 decimal in stage 3 (all p < 0.0001) and 0.01 in stage 4 (p = 0.38). Even in eyes with low baseline VA ≤ 0.3, improvements were significant only in stages 1 and 2 (0.12 and 0.17 decimals, respectively). Central subfield thickness (CST) improvement was greatest in stage 3 (-229 µm, 37.6%, p < 0.0001), but uncorrelated with VA gains, unlike stages 1 and 2 (respectively: -142 µm, 27.4%; - 5 µm, 12%; both p < 0.0001). Stage 4 showed no significant CST change. Baseline disorganization of retinal inner layers and focal damage of the ellipsoid zone/external limiting membrane did not influence VA improvement in stages 1 and 2. Treatment patterns varied, with 61% receiving anti-VEGF and 39% dexamethasone, influenced by DME stage, with no significant differences between therapeutic agents. CONCLUSION: The ESASO classification, which views the retina as a neurovascular unit and integrates multiple biomarkers, surpasses single biomarkers in predicting visual outcomes. Significant functional improvement occurred only in stages 1 and 2, suggesting reversible damage, whereas stages 3 and 4 likely reflect irreversible damage.

Role of microglia in retinal neurovascular unit of diabetic retinopathy / 国际眼科杂志(Guoji Yanke Zazhi)

Diabetic retinopathy(DR)represents the primary cause of blindness among the global working-age population, and the disruption of the blood-retinal barrier is a crucial factor. Research in recent years has elucidated that DR transcends the scope of a mere microvascular disorder into a complex interplay of retinal glial cells and neurodegeneration microvascular pathology. Neuronal damage may precede vascular endothelial changes in the retinal neurovascular unit(RNVU)in the early stage of DR, and glial cell activation further exacerbates vascular barrier dysfunction. Retinal microglia are immune cells that reside in the retina and are involved in chronic inflammatory responses induced by long-term exposure to high glucose levels. Microglia secrete various inflammatory factors in response to high glucose levels, which can lead to the destruction of the blood-retinal barrier structure, increased neuronal apoptosis, and altered gliosis of Muller cells, thus affecting the retina's homeostatic balance. The RNVU has received increasing attention in recent years as a unitary structural study, and the mechanism of microglia in the RNVU and the progress of the study are reviewed.

Research progress of retinal neurovascular unit injury in glaucoma / 国际眼科杂志(Guoji Yanke Zazhi)

Glaucoma is one of the leading causes of vision loss worldwide. More and more studies have suggested that glaucoma is a complicated retinal neurovascular disease. The homeostasis imbalance of retinal neurovascular unit(RNVU)composed of neurons, glial cells and microvascular cells not only induces changes in microvascular structure and glial cells, but also affects the nerve tissue of the retina, resulting in vision loss, which there is no effective treatment to reverse, currently. Exploring the cellular composition and molecular structure of RNVU and investigating the destruction mechanism of normal cellular environment and intercellular connections in glaucoma are of great significance in exploring the pathogenesis and the treatment of glaucoma. The research progress on structural changes and dysfunction of RNVU in glaucoma are reviewed, hoping to provide new ideas for the treatment of glaucoma.

Current Treatments for Diabetic Macular Edema.

Diabetic retinopathy is a major retinal disorder and a leading cause of blindness. Diabetic macular edema (DME) is an ocular complication in patients with diabetes, and it can impair vision significantly. DME is a disorder of the neurovascular system, and it causes obstructions of the retinal capillaries, damage of the blood vessels, and hyperpermeability due to the expression and action of vascular endothelial growth factor (VEGF). These changes result in hemorrhages and leakages of the serous components of blood that result in failures of the neurovascular units (NVUs). Persistent edema of the retina around the macula causes damage to the neural cells that constitute the NVUs resulting in diabetic neuropathy of the retina and a reduction in vision quality. The macular edema and NVU disorders can be monitored by optical coherence tomography (OCT). Neuronal cell death and axonal degeneration are irreversible, and their development can result in permanent visual loss. Treating the edema before these changes are detected in the OCT images is necessary for neuroprotection and maintenance of good vision. This review describes the effective treatments for the macular edema that are therefore neuroprotective.

Contribution of the hexosamine biosynthetic pathway in the hyperglycemia-dependent and -independent breakdown of the retinal neurovascular unit.

BACKGROUND: Diabetic retinopathy (DR) remains one of the most common complications of diabetes despite great efforts to uncover its underlying mechanisms. The pathogenesis of DR is characterized by the deterioration of the neurovascular unit (NVU), showing damage of vascular cells, activation of glial cells and dysfunction of neurons. Activation of the hexosamine biosynthesis pathway (HBP) and increased protein O-GlcNAcylation have been evident in the initiation of DR in patients and animal models. SCOPE OF REVIEW: The impairment of the NVU, in particular, damage of vascular pericytes and endothelial cells arises in hyperglycemia-independent conditions as well. Surprisingly, despite the lack of hyperglycemia, the breakdown of the NVU is similar to the pathology in DR, showing activated HBP, altered O-GlcNAc and subsequent cellular and molecular dysregulation. MAJOR CONCLUSIONS: This review summarizes recent research evidence highlighting the significance of the HBP in the breakdown of the NVU in hyperglycemia-dependent and -independent manners, and thus identifies joint avenues leading to vascular damage as seen in DR and thus identifying novel potential targets in such retinal diseases.

Autophagy in the retinal neurovascular unit: New perspectives into diabetic retinopathy.

Diabetic retinopathy (DR) is one of the most prevalent retinal disorders worldwide, and it is a major cause of vision impairment in individuals of productive age. Research has demonstrated the significance of autophagy in DR, which is a critical intracellular homeostasis mechanism required for the destruction and recovery of cytoplasmic components. Autophagy maintains the physiological function of senescent and impaired organelles under stress situations, thereby regulating cell fate via various signals. As the retina's functional and fundamental unit, the retinal neurovascular unit (NVU) is critical in keeping the retinal environment's stability and supporting the needs of retinal metabolism. However, autophagy is essential for the normal NVU structure and function. We discuss the strong association between DR and autophagy in this review, as well as the many kinds of autophagy and its crucial physiological activities in the retina. By evaluating the pathological changes of retinal NVU in DR and the latest advancements in the molecular mechanisms of autophagy that may be involved in the pathophysiology of DR in NVU, we seek to propose new ideas and methods for the prevention and treatment of DR.

Single-cell transcriptomics-based multidisease analysis revealing the molecular dynamics of retinal neurovascular units under inflammatory and hypoxic conditions.

The retinal neurovascular unit (NVU) is paramount to maintaining the homeostasis of the retina and determines the progression of various diseases, including diabetic retinopathy (DR), glaucoma, and retinopathy of prematurity (ROP). Although some studies have investigated these diseases, a combined analysis of disease-wide etiology in the NUV at the single-cell level is lacking. Herein, we constructed an atlas of the NVU under inflammatory and hypoxic conditions by integrating single-cell transcriptome data from retinas from wild-type, AireKO, and NdpKO mice. Based on the heterogeneity of the NVU structure and transcriptome diversity under normal and pathological conditions, we discovered two subpopulations of Müller cells: Aqp4hi and Aqp4lo cells. Specifically, Aqp4lo cells expresses phototransduction genes and represent a special type of Müller cell distinct from Aqp4hi cells, classical Müller cells. AireKO mice exhibit experimental autoimmune uveitis (EAU) with severe damage to the NVU structure, mainly degeneration of Aqp4hi cells. NdpKO mice exhibited familial exudative vitreoretinopathy (FEVR), with damage to the endothelial barrier, endothelial cell tight junction destruction and basement membrane thickening, accompanied by the reactive secretion of proangiogenic factors by Aqp4hi cells. In both EAU and FEVR, Aqp4hi cells are a key factor leading to NVU damage, and the mechanism by which they are generated is regulated by different transcription factors. By studying the pattern of immune cell infiltration in AireKO mice, we constructed a regulatory loop of "inflammatory cells/NVU - monocytes - APCs - Ifng+ T cells", providing a new target for blocking the inflammatory cascade. Our elucidation of the cell-specific molecular changes, cell-cell interactions and transcriptional mechanisms of the retinal NVU provides new insights to support the development of multipurpose drugs to block or even reverse NVU damage.

Nerve Growth Factor Promotes Retinal Neurovascular Unit Repair: A Review.

Purpose: The purpose of this paper is to investigate how the imbalance of neurogenic factor (NGF) and its precursor (pro-NGF) mediates structural and functional impairment of retinal neurovascular unit (RNVU) that plays a role in retinal degenerative diseases.Methods: A literature search of electronic databases was performed.Results: The pro-apoptotic effect of pro-NGF and the pro-growth effect of NGF are essential for the pathological and physiological activities of RNVU. Studies show that NGF-based treatment of retinal degenerative diseases, including glaucoma, age-related macular degeneration, retinitis pigmentosa, and diabetic retinopathy, has achieved remarkable efficacy.Conclusions: RNVU plays a complex and multifaceted role in retinal degenerative diseases. The exploration of the differential signaling expression of proNGF-NGF homeostasis under physiological and pathological conditions, and the corresponding pathological processes induced by its regulation, has prompted us to focus on earlier retinal neuroprotective therapeutic strategies to prevent retinal degenerative diseases.

Research progress in the prevention and treatment of diabetic retinopathy based on retinal neurovascular unit damage and its coupling imbalance / 国际眼科杂志(Guoji Yanke Zazhi)

Diabetic retinopathy(DR), one of the common complications of diabetes, is a major cause of blindness. Traditionally, DR has been considered primarily a microvascular disease, and as research has progressed, it is now believed that disruption of the neuro-glia-vascular unit(NVU)and imbalance in its coupling mechanisms(coupling)play a key role in the early onset of DR. Understanding the cellular and molecular basis of NVU and how diabetes alters normal cellular communication and disrupts the cellular environment is important for the early prevention and treatment of DR. This paper summarizes the retinal NVU and its involvement in the molecular mechanism of DR pathogenesis, DR treatment based on retinal NVU repair, and discusses the future prospects and problems of DR.

Pyroptosis in the Retinal Neurovascular Unit: New Insights Into Diabetic Retinopathy.

Diabetic retinopathy (DR) is prevalent among people with long-term diabetes mellitus (DM) and remains the leading cause of visual impairment in working-aged people. DR is related to chronic low-level inflammatory reactions. Pyroptosis is an emerging type of inflammatory cell death mediated by gasdermin D (GSDMD), NOD-like receptors and inflammatory caspases that promote interleukin-1ß (IL-1ß) and IL-18 release. In addition, the retinal neurovascular unit (NVU) is the functional basis of the retina. Recent studies have shown that pyroptosis may participate in the destruction of retinal NVU cells in simulated hyperglycemic DR environments. In this review, we will clarify the importance of pyroptosis in the retinal NVU during the development of DR.

Flicker retinal vasodilation test using a combination of conventional electroretinogram flicker luminescence and blue wavelength autofluorescence.

Currently, the only available objective measure of functioning of the retinal neuro-vascular unit (NVU) is the flicker retinal vasodilation test (FRVT). The FRVT measures change in retinal vessel diameter after exposure to flickers of light. Unfortunately, it is dependent on a technically adept machine, which is not readily available. In this hypothesis, we propose utilization of 2 commonly available retinal diagnostic tools, the electroretinogram (ERG) and the confocal scanning laser ophthalmoscopy-based fundus auto fluorescence (cSLO-FAF), for performing the FRVT. While the conventional machine based FRVT was performing the flicker luminescence and retinal imaging simultaneously, our hypothesized protocol is dependent on a rapidly performed 2 staged test, the effects of which need to be elicited in a pilot study. As neuroprotection is becoming a therapeutic reality for diseases like diabetic retinopathy, such adaptations may make research and therapy easier.

The cells involved in the pathological process of diabetic retinopathy.

Diabetic retinopathy(DR) is an expanding global health problem, the exact mechanism of which has not yet been clarified clearly, new insights into retinal physiology indicate that diabetes-induced retinal dysfunction may be viewed as an impairment of the retinal neurovascular unit, including retinal ganglion cells, glial cells, endothelial cells, pericytes, and retinal pigment epithelium. Different retinal cells have unique structure and functions, while the interactions among which are less known. Cells are the basic unit of organism structure and function, their impairment could lead to abnormal physiological functions and even organ disorder. Considering the body is multi-dimension and the complexity of DR, one point or a single type of cell can't be used to illustrate the mechanism of occurrence and development of DR. In this review, we provided a systematic and comprehensive elaboration of the cells that are involved in the process of DR. We underlined the importance of considering the neurovascular unit, not just retinal vascular and neural cells, in understanding the pathophysiology of DR. Our studies provided a better understanding of the pathological process in DR and provide a theoretical basis for further research.