Diabetic Macular Edema: Current Understanding, Pharmacologic Treatment Options, and Developing Therapies

Identification and mechanistic analysis of neurovascular coupling related biomarkers for diabetic macular edema

Introduction

Diabetic macular edema (DME) is a major cause of vision loss in the sick with diabetic retinopathy. The occurrence of DME is closely related to the breakdown of neurovascular coupling; however, its underlying mechanism has not been fully elucidated. The aim of this study was to investigate the diagnostic biomarkers and potential molecular mechanisms associated with neurovascular coupling in DME.

Methods

The differential expression analysis, STEM, and WGCNA were performed from GSE160306 to identify hub genes. The gene expression was validated by RT-qPCR. The relevant mechanisms of action were investigated through GO, KEGG, and GSEA analyses, as well as co-expression networks. Additionally, the LASSO regression analysis and a nomogram were used to demonstrate the diagnostic effectiveness of the model. Finally, the GenDoma platform was utilized to identify drugs with potential therapeutic effects on DME.

Results

Neurotrophic factor receptor (NGFR) was identified as a hub gene related to neurovascular coupling and DME. The expression of NGFR was verified by RT-qPCR in vitro cells. GSEA analysis indicated that high expression of NGFR may affect immunity and inflammatory pathway, thereby regulating neurovascular coupling and mediating the development of DME. The NGFR co-expression network was constructed, which exhibited the correlation with the neurotrophin signaling pathway. Moreover, a diagnostic model for DME based on NGFR and PREX1 demonstrated relatively good diagnostic performance using LASSO regression analysis and the nomogram. And then the GenDoma platform identified drugs with potential therapeutic effects on DME.

Conclusion

The high expression of NGFR may lead to abnormal neurovascular coupling and participate in the occurrence of DME by regulating the immunity, inflammatory and neurotrophin signaling pathway. Detection of NGFR and related expression genes may be beneficial for monitoring the occurrence and development of DME.

Intravitreal OZURDEX vs. Intravitreal Bevacizumab for Diabetic Macular Edema: A Comprehensive Review

This comprehensive review examines the efficacy, safety, and implications of intravitreal OZURDEX and intravitreal bevacizumab in treating diabetic macular edema (DME). DME is a common complication of diabetes mellitus and a leading cause of vision loss. OZURDEX, through sustained release of dexamethasone, targets inflammation and vascular permeability, while bevacizumab inhibits vascular endothelial growth factor (VEGF), reducing angiogenesis. However, differences in safety profiles exist, with OZURDEX associated with an increased risk of intraocular pressure elevation and cataract formation and bevacizumab potentially carrying systemic risks. The choice between these treatments should be individualized, considering patient preferences, ocular and systemic comorbidities, and cost-effectiveness. Collaboration among healthcare providers is essential for the comprehensive management of DME. Future research should focus on long-term comparative studies, predictors of treatment response, and exploration of novel therapeutic targets to optimize treatment outcomes for patients with DME.

Diabetic Macular Edema Management: A Review of Anti-Vascular Endothelial Growth Factor (VEGF) Therapies

Diabetic macular edema (DME) is a major cause of vision impairment in diabetic individuals, characterized by fluid accumulation in the macula due to a breakdown of the blood-retinal barrier (BRB). This review article explores the role of anti-vascular endothelial growth factor (anti-VEGF) therapies in the management of DME. Anti-VEGF treatments, including ranibizumab, bevacizumab, and aflibercept, have revolutionized DME management by targeting VEGF, a key mediator in DME pathogenesis. We critically examined the efficacy of these therapies in reducing macular edema and improving visual acuity, assessed their safety and tolerability, and explored the variability in treatment response. The review highlights the latest advancements and future directions in anti-VEGF therapy, including novel drug delivery systems and emerging treatment paradigms. By providing a comprehensive overview of current anti-VEGF therapies, this review seeks to inform clinical practice, guide future research, and contribute to improved patient outcomes in DME management.

OCT biomarkers as predictors of visual improvement in diabetic macular edema eyes receiving dexamethasone implants

BACKGROUND

Several optical coherence tomography (OCT) biomarkers have been proposed as predictors for functional and anatomical outcomes in Diabetic Macular Edema (DME). This study aims to examine the impact of these OCT features on the visual acuity improvement of patients with DME after long-acting Dexamethasone intravitreal implants (DEX-I) injection. Furthermore, the safety and impact of DEX-I on clinical parameters, including intraocular pressure (IOP) were assessed.

METHODS

In this retrospective observational study, we reviewed the medical records of naïve and non-naïve eyes with DME who received at least one DEX-I. The primary endpoint was visual acuity improvement of ≥ 5 ETDRS letters at 1 month and 4 months after treatment. Secondary outcomes were the changes in OCT biomarkers and the impact of DEX-I on IOP at 1 and 4 months of follow-up. Linear panel regression analysis was used to test for differences in central subfield thickness (CST) over time and it was stratified according to biomarkers at baseline. Finally, a logistic regression analysis was used to identify factors predicting visual improvement at 1 and 4 months.

RESULTS

We included 33 eyes of which 63.6% were at an advanced stage of DME. Overall, CST, cube average thickness (CAT), cube volume (CV), and intraretinal cystoid spaces > 200 μm (ICS) decreased following DEX-I injection (p < 0.001). Additionally, a thicker CST at baseline was observed in eyes with better visual improvement at one month (p = 0.048). After logistic regression analysis, CST was retained as the only predictor for visual improvement at one month (p = 0.044). Furthermore, panel regression analysis identified a relation between subfoveal neuroretinal detachment (SND) at baseline and CST increase at four months. Lastly, only 15.2% of the eyes necessitated topical medication for IOP reduction, with no differences observed when stratifying between naïve and non-naïve eyes.

CONCLUSION

Our analyses suggest that a ticker baseline CST may serve as a positive predictor of early visual improvement and SND presence at baseline may be a negative prognostic factor for CST increase 4 months after DEX-I injection. Other well-known biomarkers, such as disorganization of the inner retinal layers (DRIL) and hyperreflective foci (HF), did not demonstrate prognostic value on visual outcomes, at least within the first four months following the injection.

Early-switch versus late-switch in patients with diabetic macular edema: a cost-effectiveness study

Background

To evaluate the cost-effectiveness of early- versus late-switch to the intravitreal-dexamethasone implant (DEX-i) in patients with diabetic macular edema (DME) who did not adequately respond to vascular endothelial growth factor inhibitors (anti-VEGF).

Methods

Retrospective analysis of a multicenter Clinical Data Registry. The registry included DME eyes who received 3 intravitreal anti-VEGF injections (early-switch) or > 3 intravitreal anti-VEGF injections (late-switch) before switching to DEX-i injections. The primary outcome was to estimate the incremental cost needed to obtain a best-corrected visual acuity (BCVA) improvement ≥ 0.1 or a central-retinal thickness CRT ≤ 250 μm.

Results

The analysis included 108 eyes, 32 (29.6%) and 76 (70.4%) in the early- and late-switch groups, respectively. Early-switch strategy was associated with a cost saving of €3,057.8; 95% CI: €2,406.4–3,928.4, p < 0.0001). Regarding incremental-cost-effectiveness ratio, late-switch group was associated with an incremental cost of €25,735.2 and €13,533.2 for achieving a BCVA improvement ≥ 0.1 at month 12 and at any of the time-point measured, respectively. At month 12, 38 (35.2%) eyes achieved a BCVA improvement ≥ 0.1. At month 12, 52 (48.1) eyes had achieved a CRT ≤ 250 micron. As compared to baseline, the mean (95% CI) CRT reduction was − 163.1 (− 212.5 to − 113.7) µm and − 161.6 (− 183.8 to − 139.3) µm in the early-switch and late-switch groups, respectively, p = 0.9463.

Conclusions

In DME eyes, who did not adequately respond to anti-VEGF, switching to DEX-i at early stages (after the first 3-monthly injections) was found to be more cost-effective than extending the treatment to 6-monthly injections of anti-VEGF.

Update on Viral Gene Therapy Clinical Trials for Retinal Diseases

In 2001, the first large animal was successfully treated with a gene therapy that restored its vision. Lancelot, the Briard dog that was treated, suffered from a human childhood blindness called Leber's congenital amaurosis type 2. Sixteen years later, the gene therapy was approved by the U.S. Food and Drug Administration. The success of this gene therapy in dogs led to a fast expansion of the ocular gene therapy field. By now every class of inherited retinal dystrophy has been treated in at least one animal model and many clinical trials have been initiated in humans. In this study, we review the status of viral gene therapies for the retina, with a focus on ongoing human clinical trials. It is likely that in the next decade we will see several new viral gene therapies approved.

Longitudinal Photoreceptor Phenotype Observation and Therapeutic Evaluation of a Carbonic Anhydrase Inhibitor in a X-Linked Retinoschisis Mouse Model

Purpose

To study the long-term photoreceptor changes and to evaluate the effects of topical application of a carbonic anhydrase inhibitor (CAI) in a mouse model of X-linked retinoschisis (XLRS).

Methods

Conventional electroretinograms (ERGs) and dark-adapted 10-Hz flicker ERGs were recorded in control and Rs1^−/Y mice generated with CRISPR/Cas9. ON-pathway blocker 2-amino-4-phosphobutyric acid (APB) was injected intravitreally. Morphology was evaluated with histology and optical coherence tomography (OCT). Mice were treated with a CAI inhibitor brinzolamide eye drops (10 mg/ml) three times a day for 3 months. OCT and ERG findings at 1, 4, and 10 months were analyzed.

Results

Negative ERGs and retinal cavities were evident in Rs1^−/Y mice. Both a-wave and b-wave amplitudes decreased with age when compared with age-matched controls. The APB-isolated a-wave (a′) amplitudes of Rs1^−/Y mice were reduced in all age groups. In dark-adapted 10-Hz flicker ERG, the amplitude-intensity curve of Rs1^−/Y mice shifted down. The thickness of ONL and IS/OS decreased in Rs1^−/Y mice. CAI reduced the splitting retinal cavities but didn't affect the ERG.

Conclusions

In addition to post receptoral impairments, photoreceptor cells underwent progressive dysfunction since early age in Rs1^−/Y mice. Long-term CAI treatment improved the shrinkage of the splitting retinal cavity, while no functional improvement was observed.

Current and Novel Therapeutic Approaches for Treatment of Diabetic Macular Edema

Diabetic macular edema (DME) is a major ocular complication of diabetes mellitus (DM), leading to significant visual impairment. DME's pathogenesis is multifactorial. Focal edema tends to occur when primary metabolic abnormalities lead to a persistent hyperglycemic state, causing the development of microaneurysms, often with extravascular lipoprotein in a circinate pattern around the focal leakage. On the other hand, diffusion edema is due to a generalized breakdown of the inner blood-retinal barrier, leading to profuse early leakage from the entire capillary bed of the posterior pole with the subsequent extravasation of fluid into the extracellular space. The pathogenesis of DME occurs through the interaction of multiple molecular mediators, including the overexpression of several growth factors, including vascular endothelial growth factor (VEGF), insulin-like growth factor-1, angiopoietin-1, and -2, stromal-derived factor-1, fibroblast growth factor-2, and tumor necrosis factor. Synergistically, these growth factors mediate angiogenesis, protease production, endothelial cell proliferation, and migration. Treatment for DME generally involves primary management of DM, laser photocoagulation, and pharmacotherapeutics targeting mediators, namely, the anti-VEGF pathway. The emergence of anti-VEGF therapies has resulted in significant clinical improvements compared to laser therapy alone. However, multiple factors influencing the visual outcome after anti-VEGF treatment and the presence of anti-VEGF non-responders have necessitated the development of new pharmacotherapies. In this review, we explore the pathophysiology of DME and current management strategies. In addition, we provide a comprehensive analysis of emerging therapeutic approaches to the treatment of DME.

Expression of Long Non-Coding RNA (lncRNA) SNHG5 in Patients with Refractory Diabetic Macular Edema and Its Regulatory Mechanism

BACKGROUND The aim of this study was to assess use of lncRNAs as biomarkers in serum and aqueous humor of patients with diabetic macular edema (DME). MATERIAL AND METHODS Optical coherence tomography and fundus photography were used to analyze the retinal features of the patients. RT-qPCR was used to analyze the differential expression of lncRNA snhg5 in patients who have idiopathic macular hole (MH), DME, or refractory DME. The relationship between SNHG5 and the clinical characteristics of the patients was analyzed. The effect of SNHG5 on the hyperplasia and apoptosis of human retino-microvascular endothelial cells (HRMECs) and its mechanism were analyzed in vitro. RESULTS Patients with idiopathic MH developed retinal nerve epithelium rupture and retinal fundus thickening, and patients with DME or refractory DME showed significant macular edema with hemorrhaging. The refractory DME patients improved after treatment but still showed significant macular edema and multiple laser scarring. SNHG5 expression was not only low in the atrial fluid and plasma in DME patients, but also lower in the refractory DME group compared to the idiopathic MH patients. SNHG5 expression in the aqueous humor and plasma was negatively correlated with disease duration, body mass index, and levels of fasting blood glucose, glycated hemoglobin, proteinuria, and glycosuria. In the in vitro experiments, SNHG5 expression was significantly downregulated in high glucose-induced HMECs. After SNHG5 overexpression, cell proliferation, angiogenesis, and VEGF-A protein levels were distinctly downregulated. CONCLUSIONS SNHG5 correlates with the development of DME and is a potential target for therapy.

Comparison of multicolor scanning laser ophthalmoscopy and optical coherence tomography angiography for detection of microaneurysms in diabetic retinopathy

This study aimed to evaluate the usefulness of multicolor (MC) scanning laser ophthalmoscopy (MC-SLO) in detecting microaneurysm (MA) in eyes with diabetic retinopathy (DR). This was a retrospective cross-sectional study. Eyes with DR underwent fluorescein angiography (FA), MC-SLO, optical coherence tomography angiography (OCTA), and color fundus photography (CFP) were analyzed. The foveal region was cut in an 6 × 6 mm image and the number of MA in each image was counted by retina specialists to determine the sensitivity and positive predictive value. FA results were used as the ground standard. MAs were classified as those with early, late, or no dye leakage based on FA images. Fifty-four eyes of 35 patients with an average age of 64.5 ± 1.24 years were included. The sensitivity of MA detection was 37.3%, 15.3%, and 4.12% in MC-SLO, OCTA, and CFP, respectively (P < 0.01 in each pair).The positive predictive value was 66.4%, 46.4%, and 27.6% in MC, OCTA, and CFP, respectively (P < 0.01 in each pair). Sensitivity for MAs with early leakage was 36.4% in MC-SLO, which was significantly higher than 4.02% in OCTA. MC-SLO was more useful in detecting MA in eyes with DR than OCTA.

Ocular Complications of Obstructive Sleep Apnea

Obstructive sleep apnea (OSA), the most common form of sleep-disordered breathing, is characterized by repetitive episodes of paused breathing during sleep, which in turn induces transient nocturnal hypoxia and hypercapnia. The high prevalence of OSA and its associated health consequences place a heavy burden on the healthcare system. In particular, the consequent episodic oxygenic desaturation/reoxygenation series and arousals from sleep in patients with OSA have the potential to trigger oxidative stress, elevated systemic inflammatory responses, and autonomic dysfunction with sympathetic activation. Given these adverse side-effects, OSA is highly correlated to many eye diseases that are common in everyday ophthalmic practices. Some of these ocular consequences are reversible, but they may permanently threaten a patient’s vision if not treated appropriately. Here, this article seeks to review the ocular consequences and potential pathophysiologic associations in patients with OSA. Understanding these OSA-related eye diseases may help clinicians provide comprehensive care to their patients.

Expression of microRNA-155-5p in patients with refractory diabetic macular edema and its regulatory mechanism

Diabetic macular edema (DME) is the main cause of visual impairment in diabetic patients, but its pathogenesis remains unclear. The purpose of the present study was to analyze the expression of microRNA (miR)-155-5p in patients with DME and its regulatory mechanism. A total of 72 patients diagnosed with DME and 17 with idiopathic macular hole (MH) were recruited. Among samples from patients with DME, 45 were DME and 27 were refractory DME, whereas patients with idiopathic MH served as the control group. Optical coherence tomography and fundus photograph analysis revealed that part of the retina in the fundus of patients with DME was thickened, with macular edema occurring simultaneously. In refractory patients with DME, macular edema was associated with bleeding and a dark cavity between retinal layers. Through reverse transcription-quantitative PCR analysis, miR-155-5p was highly expressed in the aqueous humor (AH) and plasma of patients with DME compared with that in patients with MH, and this was even higher in the refractory DME group. Upon analyzing patient clinical data, the difference in miR-155-5p expression in the AH and plasma was positively associated with disease course, body mass index, fasting blood-glucose, glycated hemoglobin, proteinuria and glycosuria. The expression of miR-155-5p was not significantly different based on hemoglobin, intraocular pressure and sex. The aforementioned results indicate that miR-155-5p might promote the development of DME. To further study the molecular mechanism, human retinal microvascular endothelial cells (HRMECs) were cultured and treated with high glucose in vitro. The results showed that miR-155-5p expression was significantly upregulated in HRMECs induced by high glucose. After inhibiting the expression of miR-155-5p, cell proliferation, angiogenesis and VEGF protein levels were significantly downregulated, whereas miR-155-5p mimics had the opposite effect. In summary, miR-155-5p is closely associated with DME and is a potential target for refractory DME treatment.

Rho-Kinase Inhibitors for the Treatment of Refractory Diabetic Macular Oedema

Diabetic macular oedema (DMO) is one of the leading causes of vision loss associated with diabetic retinopathy (DR). New insights in managing this condition have changed the paradigm in its treatment, with intravitreal injections of antivascular endothelial growth factor (anti-VEGF) having become the standard therapy for DMO worldwide. However, there is no single standard therapy for all patients DMO refractory to anti-VEGF treatment; thus, further investigation is still needed. The key obstacles in developing suitable therapeutics for refractory DMO lie in its complex pathophysiology; therefore, there is an opportunity for further improvements in the progress and applications of new drugs. Previous studies have indicated that Rho-associated kinase (Rho-kinase/ROCK) is an essential molecule in the pathogenesis of DMO. This is why the Rho/ROCK signalling pathway has been proposed as a possible target for new treatments. The present review focuses on the recent progress on the possible role of ROCK and its therapeutic potential in DMO. A systematic literature search was performed, covering the years 1991 to 2021, using the following keywords: "rho-Associated Kinas-es", "Diabetic Retinopathy", "Macular Edema", "Ripasudil", "Fasudil" and "Netarsudil". Better insight into the pathological role of Rho-kinase/ROCK may lead to the development of new strategies for refractory DMO treatment and prevention.

Anxiety and depression in patients who receive anti-VEGF treatment and the usability and feasibility of e-mental health support: the E-PsEYE pilot study

Purpose

E‐PsEYE is an internet‐based, guided self‐help course, following the principles of cognitive behavioural therapy, to reduce anxiety and depression in patients with retinal exudative diseases who receive anti‐vascular endothelial growth factor (anti‐VEGF) treatment. The purpose of this study was to determine the prevalence and related factors of anxiety and depression in this population and evaluate the usability and feasibility of E‐PsEYE.

Methods

Symptoms of anxiety and depression and related factors were determined in 90 patients (mean age 77 years, 58% female), based on multiple logistic regression analysis. Five patients with mild to moderate depression/anxiety tested the usability of E‐PsEYE. They were asked to think aloud while completing two modules of the intervention and freely explore system features. The feasibility of the total E‐PsEYE intervention was tested in 14 patients with mild to moderate depression/anxiety, based on a single arm pre‐post study with a follow‐up of three months: fidelity, acceptability, feasibility of study methods and potential effectiveness were explored.

Results

Fifty‐three percent of the total study population experienced at least mild anxiety and/or depression symptoms. Especially female patients (odds ratio (OR) 3.89, 95% confidence interval (CI) 1.33–11.40), those who experienced limitations in daily life activities due to vision loss (OR 9.67; 95% CI 3.18–29.45) and those who experienced loneliness (OR 3.53, 95% CI 1.14–10.95) were more likely to have anxiety/depression. The usability study raised several possibilities for improvement, based on which E‐PsEYE was improved. The feasibility study showed adequate fidelity and acceptability. Most participants were satisfied with the results (79%). There was a high response rate, no loss to follow‐up and mental health problems decreased in more than half of the patients. The Wilcoxon signed rank test indicated lower post‐test ranks compared to pre‐test ranks (depression Z −1.34, p = 0.18; anxiety Z −1.45, p = 0.15).

Conclusions

Mental health problems are prevalent in patients who receive anti‐VEGF treatment. Healthcare providers should recognise these problems and related factors in order to refer patients to appropriate care in a timely manner. Outcomes on the usability and feasibility of E‐PsEYE are promising as a prelude to performing a randomised controlled trial, which will shed more light on its (cost‐)effectiveness.

Optogenetic Modulation of Intraocular Pressure in a Glucocorticoid-Induced Ocular Hypertension Mouse Model

Purpose

Steroid-induced glaucoma is a common form of secondary open angle glaucoma characterized by ocular hypertension (elevated intraocular pressure [IOP]) in response to prolonged glucocorticoid exposure. Elevated IOP occurs with increased outflow resistance and altered trabecular meshwork (TM) function. Recently, we used an optogenetic approach in TM to regulate the 5-phosphatase, OCRL, which contributes to regulating PI(4,5)P2 levels. Here, we applied this system with the aim of reversing compromised outflow function in a steroid-induced ocular hypertension mouse model.

Methods

Elevated IOP was induced by chronic subconjunctival dexamethasone injections in wild-type C57Bl/6j mice. AAV2 viruses containing optogenetic modules of cryptochrome 2 (Cry2)-OCRL-5ptase and CIBN-GFP were injected into the anterior chamber. Four weeks after viral expression and dexamethasone exposure, IOP was measured by tonometer and outflow facility was measured by perfusion apparatus. Human TM cells were treated with dexamethasone, stimulated by light and treated with rhodamine-phalloidin to analyze actin structure.

Results

Dexamethasone treatment elevated IOP and decreased outflow facility in wild-type mice. Optogenetic constructs were expressed in the TM of mouse eyes. Light stimulation caused CRY2-OCRL-5ptase to translocate to plasma membrane (CIBN-CAAX-GFP) and cilia (CIBN-SSTR3-GFP) in TM cells, which rescued the IOP and outflow facility. In addition, aberrant actin structures formed by dexamethasone treatment were reduced by optogenetic stimulation in human TM cells in culture.

Conclusions

Subcellular targeting of inositol phosphatases to remove PIP2 represents a promising strategy to reverse defective TM function in steroid-induced ocular hypertension.

Translational Relevance

Targeted modulation of OCRL may be used to decrease steroid-induced elevated IOP.

Reduction in Retinal Thickness Fluctuations After Treatment With Fluocinolone Acetonide Implant for DME: A Post-Hoc Analysis of the USER Study

BACKGROUND AND OBJECTIVE

Assess fluocinolone acetonide implant (FAc) effects on diabetic macular edema (DME) retinal thickness fluctuations.

PATIENTS AND METHODS

A post-hoc chart review of the real-world USER study analyzed patients receiving 0.2 μg/day FAc implant. The percentage of eyes with central subfield thickness (CST) of 300 µm or less were compared pre- and post-FAc implant; mean retinal thickness amplitude (RTA), retinal thickness standard deviation (RTSD), and two case studies were analyzed.

RESULTS

One hundred thirty patients (mean age: 69.6 years) presented; CST was available for 120 of 160 treated eyes. Mean RTA decreased significantly post-FAc implant (P < .001) regardless of baseline visual acuity (VA). Correlations with last-observed VA (R²) were: RTA, 0.1197; retinal thickness standard deviation (RTSD), 0.1526; and area under the CST-time curve (AUC CST), 0.0981. After FAc implant, the percentage of eyes with CST of 300 μm or less was significantly greater versus baseline (P < .05).

CONCLUSIONS

Retinal thickness fluctuations significantly declined after FAc and correlated with improvement in VA. Both RTSD and RTA measures correlated more closely to last observed VA than AUC CST itself. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:298-306.].

The role of vascular endothelial protein tyrosine phosphatase on nitric oxide synthase function in diabetes: from molecular biology to the clinic

Endothelial nitric oxide synthase (eNOS) and receptor-type vascular endothelial protein tyrosine phosphatase (VE-PTP) are one of the majors signaling pathways related to endothelial health in diabetes. Several reports have shown that the inhibition of VE-PTP can lead the nitric oxide production, although repeated studies showed that VE-PTP regulated the eNOS exclusive at Ser1177 in indirect-manner. A recent, exciting paper (Siragusa et al. in Cardiovasc Res, 2020. https://doi.org/10.1093/cvr/cvaa213 ), showing that VE-PTP regulates eNOS in a direct-manner, dephosphorylating eNOS at Tyr81 and indirect at Ser1177 and the effects of a VE-PTP inhibitor, AKB-9778, in the blood pressure from diabetic patients.

Visual Acuity Gain Profiles and Anatomical Prognosis Factors in Patients with Drug-Naive Diabetic Macular Edema Treated with Dexamethasone Implant: The NAVEDEX Study

Brief Summary Statement

NAVEDEX (NAive diabetic macular Edema treated by DEXamethasone implant) study is a real-life multi-center study on drug-naive diabetic macular edema treated by Dexamethasone-implant. Two different visual acuity gain (VA) profiles were identified, based on baseline visual acuity (VA). Baseline disorganization of retinal inner layers or ellipsoid zone alterations (EZAs) negatively influence final VA but has no impact on VA gain.

Abstract

The purpose of this study is to evaluate the visual acuity (VA) gain profiles between patients with drug-naive diabetic macular edema (DME) treated by dexamethasone implant (DEX-implant) and assess the baseline anatomical and functional factors that could influence the response to the treatment in real-life conditions. A retrospective, multi-center observational study included 129 eyes with drug-naive DME treated by DEX-implant. The Median follow-up was 13 months. Two groups of VA gain trajectories were identified—Group A, with 71% (n = 96) of patients whose average VA gain was less than five letters and Group B, with 29% (n = 33) of patients with an average gain of 20 letters. The probability of belonging to Group B was significantly higher in patients with baseline VA < 37 letters (p = 0.001). Ellipsoid zone alterations (EZAs) or disorganization of retinal inner layers (DRILs) were associated with a lower final VA (53.0 letters versus 66.4, p = 0.002) but without a significant difference in VA gain (4.9 letters versus 6.8, p = 0.582). Despite a low baseline VA, this subgroup of patients tends to have greater visual gain, encouraging treatment with DEX-implant in such advanced-stage disease. However, some baseline anatomic parameters, such as the presence of EZAs or DRILs, negatively influenced final vision.

The Tie2 signaling pathway in retinal vascular diseases: a novel therapeutic target in the eye

Background

Retinal vascular diseases such as neovascular age-related macular degeneration, diabetic retinopathy and/or diabetic macular edema, and retinal vein occlusion with macular edema—share several key pathophysiologic aspects including neovascularization, vascular permeability, and inflammation. The role of vascular endothelial growth factor (VEGF) in these processes, and the therapeutic benefits of VEGF inhibition, have been well characterized. Anti-VEGF therapy is highly effective for many patients but is not uniformly effective in all patients and imposes a significant treatment burden. More recently, the role of the Tie2 signaling pathway in the pathophysiology of retinal vascular diseases has been investigated, and the Tie2 pathway represents a novel therapeutic target for these conditions.

Areas covered

The index review describes the Tie2 pathway and its complementary role to the VEGF pathway in the angiogenesis cascade and will summarize studies of molecules in development to therapeutically modulate the Tie2 pathway in retinal vascular diseases.

Conclusions

Activation of the Tie2 pathway leads to downstream signaling that promotes vascular health and stability and decreases vascular permeability and inflammation. AXT107 is a collagen IV–derived synthetic peptide with a dual mechanism of action that involves suppression of VEGF signaling and activation of the Tie2 pathway; these actions are accomplished by AXT107 binding to and disrupting different integrin, leading to blockade of the VEGF receptor and rearrangement of cellular Tie2 rendering it susceptible to Ang2 agonism. Other Tie2 agonist compounds are also in development, including faricimab and razuprotafib. Tie2 activation only modestly impacts angiogenesis on its own but significantly potentiates VEGF suppression. Co-regulation of the VEGF and Tie2 signaling pathways has the potential to improve functional and structural outcomes in eyes with retinal vascular diseases.

In Vitro and Ex Vivo Evaluation of Nepafenac-Based Cyclodextrin Microparticles for Treatment of Eye Inflammation

The aim of this study was to design and evaluate novel cyclodextrin (CD)-based aggregate formulations to efficiently deliver nepafenac topically to the eye structure, to treat inflammation and increase nepafenac levels in the posterior segment, thus attenuating the response of inflammatory mediators. The physicochemical properties of nine aggregate formulations containing nepafenac/γ-CD/hydroxypropyl-β (HPβ)-CD complexes as well as their rheological properties, mucoadhesion, ocular irritancy, corneal and scleral permeability, and anti-inflammatory activity were investigated in detail. The results were compared with a commercially available nepafenac suspension, Nevanac^® 3 mg/mL. All formulations showed microparticles, neutral pH, and negative zeta potential (–6 to –27 mV). They were non-irritating and nontoxic and showed high permeation through bovine sclera. Formulations containing carboxymethyl cellulose (CMC) showed greater anti-inflammatory activity, even higher than the commercial formulation, Nevanac^® 0.3%. The optimized formulations represent an opportunity for topical instillation of drugs to the posterior segment of the eye.

Anti-VEGF Treatment of Diabetic Macular Edema: Two-Year Visual Outcomes in Routine Clinical Practice

Purpose

The purpose of this study was to evaluate 2-year visual outcomes in patients with diabetic macular edema (DME) treated with anti-VEGF agents in a routine clinical setting.

Methods

The medical records of patients treated with ranibizumab or aflibercept due to DME at the Eye Hospital, University Medical Centre Ljubljana, Slovenia, between January 2016 and March 2019 were retrospectively reviewed. After applying inclusion and exclusion criteria, 123 patients (123 eyes) were included in the study.

Results

Baseline visual acuity (VA) was 60.9 ± 15.2 letters (median 63; range 7-85). Baseline central retinal subfield thickness (CRT) was 440.7 ± 132.5 μm (median 430; range 114-1000). No significant change in VA over 2 years was found (mean change +2.1 ± 16.8 letters (median 2; range -53-52)). However, there was a significant change in VA in the subgroup with baseline VA <70 letters (mean change +5.7 ± 17.9 letters (median 5; range -52-52)). VA gains of ≥15 letters were achieved in 25 eyes (20.3%). Changes in CRT were significant over 2 years. Patients received 4.5 ± 2.1 (median 5, range 1-9) and 2.6 ± 2.3 (median 2, range 0-8) injections in the first and second years, respectively.

Conclusions

The two-year visual outcomes in this retrospective analysis appear to be comparable to previously reported outcomes in routine clinical practice. Our analysis provides some information about the effectiveness of anti-VEGF treatment in routine clinical practice in Slovenia. More intensive treatment should be implemented in the management of patients in order to achieve better visual outcomes.

Combination of Intravitreal Bevacizumab and Topical Dorzolamide versus Intravitreal Bevacizumab Alone for Diabetic Macular Edema: A Randomized Contralateral Clinical Trial

Purpose

To evaluate the efficacy of three intravitreal bevacizumab (IVB) injections versus the same combined with 2% of topical dorzolamide in the treatment of diabetic macular edema (DME).

Methods

In this randomized double-masked clinical trial, 32 eyes of 16 treatment-naive patients with bilateral DME were enrolled. The eyes were randomly assigned to receive three monthly injections of IVB (1.25 mg) plus topical dorzolamide 2% twice daily or IVB (1.25 mg) plus topical artificial tear twice daily. Best-corrected visual acuity (BCVA) was the primary outcome of the study followed by the central macular thickness (CMT) and central macular volume (CMV) as the secondary outcomes.

Results

Mean BCVA changes were insignificant in both groups. It changed from 0.21 ± 0.08 logMAR at baseline to 0.23 ± 0.09 (P=0.24) in the combination group and from 0.18 ± 0.09 logMAR to 0.21 ± 0.09 (P=0.11) in the IVB alone group, at 3 months, respectively. Changes in mean CMT and CMV were significant in both groups. However, the difference between the groups was not significant at all the visits. In the study, no major ocular complication or systemic side effects were noted regarding IVB or topical dorzolamide.

Conclusion

This randomized contralateral clinical trial demonstrated that adjuvant topical dorzolamide with IVB injection had no additional effects on IVB in the treatment of DME over a three-month course. This trial is registered with the Iranian Registry of Clinical Trials under the registration code IRCT20131229015975N5.

Methylglyoxal, a Highly Reactive Dicarbonyl Compound, in Diabetes, Its Vascular Complications, and Other Age-Related Diseases

The formation and accumulation of methylglyoxal (MGO), a highly reactive dicarbonyl compound, has been implicated in the pathogenesis of type 2 diabetes, vascular complications of diabetes, and several other age-related chronic inflammatory diseases such as cardiovascular disease, cancer, and disorders of the central nervous system. MGO is mainly formed as a byproduct of glycolysis and, under physiological circumstances, detoxified by the glyoxalase system. MGO is the major precursor of nonenzymatic glycation of proteins and DNA, subsequently leading to the formation of advanced glycation end products (AGEs). MGO and MGO-derived AGEs can impact on organs and tissues affecting their functions and structure. In this review we summarize the formation of MGO, the detoxification of MGO by the glyoxalase system, and the biochemical pathways through which MGO is linked to the development of diabetes, vascular complications of diabetes, and other age-related diseases. Although interventions to treat MGO-associated complications are not yet available in the clinical setting, several strategies to lower MGO have been developed over the years. We will summarize several new directions to target MGO stress including glyoxalase inducers and MGO scavengers. Targeting MGO burden may provide new therapeutic applications to mitigate diseases in which MGO plays a crucial role.

Comparison of aflibercept and ranibizumab in diabetic macular edema associated with subretinal detachment

PURPOSE

To compare the efficacy of ranibizumab and aflibercept in the treatment of diabetic macular edema associated with subfoveal retinal detachment.

METHODS

This is a retrospective, comparative study. The treatment-naïve diabetic macular edema patients who had diabetic macular edema associated with subfoveal retinal detachment and underwent intravitreal aflibercept or intravitreal ranibizumab treatment were included. The patients were treated on a pro re nata treatment regimen after a loading dose of 3-monthly injections and the follow-up time was 12 months. The primary outcome measure of this study was the presence of subfoveal retinal detachment after treatment at different time points. The secondary outcome measures were the change in best corrected visual acuity and central retinal thickness.

RESULTS

A total of 46 eyes of 46 patients were included. The aflibercept group consisted of 20 and the ranibizumab group consisted of 26 eyes. During the follow-up period of 12 months, subfoveal retinal detachment was completely resolved in 75% versus 57.7% of the eyes at month 3 (p = 0.2), 90% versus 76.9% at month 6 (p = 0.2), 90% versus 65.4% at month 9 (p = 0.05), and 100% versus 80.8% at month 12 (p = 0.03) in the intravitreal aflibercept versus intravitreal ranibizumab groups. The change in best corrected visual acuity was not statistically different between the groups at months 3, 6, 9, and 12, respectively (p > 0.05 for all).

CONCLUSION

Both intravitreal aflibercept and intravitreal ranibizumab were effective in regards to anatomical and functional outcomes of diabetic macular edema patients associated with subfoveal retinal detachment. Interestingly, intravitreal aflibercept seemed more effective than intravitreal ranibizumab in the resolution of subfoveal retinal detachment at month 12.

Interleukin-6 and Diabetic Retinopathy: A Systematic Review and Meta-Analysis

BACKGROUND

Interleukin-6 (IL-6) is produced by a variety of cells involved in inflammation and acts as local intensification signals in pathological processes associated with chronic eye inflammation. This meta-analysis was performed to provide a better understanding of the relationship between IL-6 and diabetic retinopathy.

METHODS

The study was started with systematic search for literatures by using the PubMed, Web of Science and Embase online databases. The standard mean difference (SMD) and its 95% confidence intervals (CIs) were was included and then pooled with a random effects model.

RESULTS

Thirty-one articles, containing1099 DR patients and 1010 controls, were included in this meta-analysis. The level of IL-6 in the DR group was found to be higher than that in the control group (SMD: 2.12, 95% CI: 1.53-2.70, p < 0.00001).Obvious heterogeneity existed between the studies (p < 0.00001, I² = 96%). So a subgroup analysis and sensitivity analysis were performed. Removing the sensitivity studies, the stability of the overall treatment effect was good. Subgroup analysis showed that the levels of IL-6 in case group were observed to be higher than those in the control group; and the IL-6 levels in the proliferative diabetic retinopathy (PDR) group were also higher than those in the non-proliferative diabetic retinopathy (NPDR) group. (SMD: 0.78, 95% CI: 0.26-1.31, p=  0.003) Conclusion: The results from this current meta-analysis indicated that increased level of IL-6 generally exist in DR patients. And it may associated with the severity of DR. However, large-scale and high-quality studies in future are required to confirm the present findings.

In vivo measurement of trabecular meshwork stiffness in a corticosteroid-induced ocular hypertensive mouse model

Ocular corticosteroids are commonly used clinically. Unfortunately, their administration frequently leads to ocular hypertension, i.e., elevated intraocular pressure (IOP), which, in turn, can progress to a form of glaucoma known as steroid-induced glaucoma. The pathophysiology of this condition is poorly understood yet shares similarities with the most common form of glaucoma. Using nanotechnology, we created a mouse model of corticosteroid-induced ocular hypertension. This model functionally and morphologically resembles human ocular hypertension, having titratable, robust, and sustained IOPs caused by increased resistance to aqueous humor outflow. Using this model, we then interrogated the biomechanical properties of the trabecular meshwork (TM), including the inner wall of Schlemm's canal (SC), tissues known to strongly influence IOP and to be altered in other forms of glaucoma. Specifically, using spectral domain optical coherence tomography, we observed that SC in corticosteroid-treated mice was more resistant to collapse at elevated IOPs, reflecting increased TM stiffness determined by inverse finite element modeling. Our noninvasive approach to monitoring TM stiffness in vivo is applicable to other forms of glaucoma and has significant potential to monitor TM function and thus positively affect the clinical care of glaucoma, the leading cause of irreversible blindness worldwide.

Anti-angiogenic therapy for diabetic macular edema

Diabetic retinopathy remains one of the greatest challenges for healthcare system worldwide despite the fact that the incidence of visual acuity impairment in diabetic population has decreased due to examination quality improvement and dynamic observation of patients. Visual acuity impairment in diabetic patients is often related to diabetic macular edema. Until recently, laser photocoagulation of the retina was regarded as gold standard for diabetic macular edema treatment. Laser photocoagulation of the retina provides visual acuity stabilization rather than improvement. Since early 2000s, pharmacological approach to this severe disease has been established. As vascular endothelial growth factor (VEGF) is one of the crucial factors involved in the pathogenesis of diabetic retinal disorders, VEGF inhibitors are now recognized as a treatment of choice for diabetic macular edema. This article considers results of different clinical trials investigating anti-VEGF therapy efficacy in DME treatment.

Tumor necrosis factor-α and diabetic retinopathy: Review and meta-analysis

BACKGROUND

Tumor necrosis factor-alpha (TNF-α) is produced by multinuclear giant cells and acts as local intensification signals in pathological processes associated with chronic eye inflammation. This meta-analysis was performed to provide a better understanding of the relationship between TNF-α and diabetic retinopathy (DR).

METHOD

Online electric databases were searched to retrieve all relevant articles published before October 2017. The standard mean difference (SMD) and their 95% confidence intervals (CI) were included and then pooled with a random effects model.

RESULTS

A total of 16 articles with 1286 participants were included in this meta-analysis. No difference in the level of TNF-α was found between DR patients and healthy controls (SMD = 0.39, 95% CI = -0.09 to 0.68, P = 0.01). Subgroup analysis showed that with respect to the level of TNF-α, the association was significant for studies conducted in Europe (SMD: 0.57, 95% CI: 0.11-1.02, P = 0.01), patients with type 1 DM (SMD: 1.06, 95% CI: 0.09-2.04, P = 0.03), studies based on serum samples (SMD: 0.57, 95% CI: 0.12-1.02, P = 0.01) and studies with a sample size >50 (SMD: 0.39, 95% CI: 0.03-0.75, P = 0.04).

CONCLUSION

The results this meta-analysis indicated that the level of TNF-α in DR patients was significantly different from that in the healthy controls, so TNF-α represents a candidate biomarker for DR.