Diabetic macular edema: new concepts in patho-physiology and treatment

What have we learned from a decade treating patients with diabetic macular oedema with 0.19 mg fluocinolone acetonide intravitreal implant?

Diabetic macular oedema [DMO] is a prevalent and sight-threatening condition among diabetic patients, which can cause irreversible blindness. Since angiogenesis and inflammation are two key elements in the etiopathogenesis of DMO, intravitreal injections of vascular endothelial growth factor inhibitors [anti-VEGF] and sustained released intravitreal corticosteroid implants are currently considered as treatments of choice. The introduction, 10 years ago, of the 0.19 mg fluocinolone acetonide [FAc] implant for treating eyes with vision impairment associated with recurrent and persistent DMO represented an important advance. Since then, two randomized-control trials and many real-world studies have shown its good efficacy/safety profile and the replicability of its treatment regimen. The FAc implant is, in general terms well tolerated, although it is associated with intraocular pressure-[IOP] and cataract-related adverse events [AEs]. Most IOP-related AEs are effectively controlled with ocular-hypotensive therapies. The objective of this paper is to review the role of FAc implant in the treatment of DMO over the 10 years since its launch, as well as its impact on clinical practice outcomes.

Efficacy of ranibizumab and aflibercept on reducing maximum diameter of largest cyst in diabetic cystoid macular edema: MARMASIA study group

PurposeThis study aimed to compare the effect of intravitreal aflibercept (IVA) and ranibizumab (IVR) on the maximal diameter of the largest intraretinal cyst (mdIRC), indicating chronicity in patients with diabetic cystoid macular edema (CME).MethodsThis retrospective, comparative study included a subgroup of patients from the MARMASIA Study with treatment-naïve diabetic CME who had IVA (IVA group) or IVR (IVR group) on a pro re nata regimen after a loading dose of 3-monthly injections and followed-up for 24 months. Best-corrected visual acuity (logMAR), central macular thickness (CMT, µm), and mdIRC (µm) and their changes during the study period in the IVA and IVR groups were compared.ResultsA total of 175 eyes (65 [37.1%] in IVA and 110 [62.9%] in IVR group) of 113 patients were included in the study analysis. Both groups had statistically significant improvements in BCVA and CMT during the follow-up (p < 0.05 for all), which were comparable between the groups at each time point. However, the mean reduction in mdIRCs was consistently and significantly higher in the IVA group compared to the IVR group at each follow-up examination (F[1, 3.52] = 6.93, p = 0.009).ConclusionIVA seems to have a greater impact in reducing cyst sizes than IVR in diabetic CME.

Systematic Inflammation and Oxidative Stress Elevation in Diabetic Retinopathy and Diabetic Patients with Macular Edema

This study investigates the association between diabetic retinopathy (DR) and its complication, diabetic macular edema (DME), and compared it with biomarkers of oxidative stress. This study aimed to compare the main indicators of the development of diabetic retinopathy measured as parameters of oxidative stress and compared to lipid oxidation, DNA damage, and cytokine levels and to monitor their quantitative manifestation in DME. This study evaluated 134 patients (62 males and 72 females; aged 62.10 ± 11.22 years) and divided them into two groups: type 2 diabetes mellitus with DR and type 2 diabetes mellitus with DME. All results were compared with healthy volunteers (n = 94) and showed that patients with DME had significantly higher levels of ROS, cytokine production, lipid oxidation, and DNA damage. In addition, patients with DME had decreased levels of nitric oxide (NO) and an impaired NO synthase (NOS) system (p < 0.05). These findings suggest that patients with DR and DME are unable to compensate for high levels of oxidative stress. Reduced NO levels in patients with DME may be due to impaired NO availability. This study highlights compromised oxidative status as a contributing factor to DME in patients with decompensated type 2 diabetes mellitus. An assessment of oxidative stress levels and inflammatory biomarkers may aid in the early detection and prediction of diabetic complications.

The Combination of Retinal Neurovascular Unit Changes With Carotid Artery Stenosis Enhances the Prediction of Ischemic Stroke

Purpose

We aimed to analyze retinal neurovascular unit (RNVU) alterations and function via optical coherence tomography angiography (OCTA) and full-field electroretinography (ERG) in patients with ischemic stroke (IS).

Methods

OCTA was used to measure RNVU changes in 229 participants (101 with IS and 128 healthy controls). The RETeval device was used to record full-field electroretinograms (FERGs) in 40 participants (14 with IS and 26 healthy controls). Logistic regression models for IS were constructed. Receiver operating characteristic (ROS) curves were constructed to assess the predictive value of various models for IS.

Results

Patients with ipsilateral internal carotid artery stenosis (ICAS) had a greater occurrence of IS. A decrease in the vascular density (VD) of the parafovea, FD-300, and nasal optic disc; a decrease in the thickness of the retinal nerve fiber layer (RNFL) around the nasal optic disc; and an increase in the acircularity index (AI) were observed in patients with IS (P < 0.05). An increase in the AI was identified as a risk factor for IS, whereas the other factors were found to be protective factors. The IS group presented a delayed a-wave implicit time and decreased b-wave amplitudes at the scotopic point. By incorporating traditional risk factors, the degree of ipsilateral ICAS, and OCTA parameters, a high predictive value for IS was achieved (area under the curve [AUC] = 0.933).

Conclusions

Patients with IS without visible fundus lesions presented changes in the RNVU, characterized by reductions in retinal VD and RNFL thickness, alongside dysfunction of photoreceptor cells and bipolar cells. The combination of RNVU changes with traditional risk factors can enhance the prediction of IS, which provides valuable guidance for monitoring this disease.

Translational Relevance

This study demonstrated that the combination of OCTA parameters, the degree of ipsilateral ICAS, and traditional risk factors could can enhance the prediction of IS. These findings provide valuable guidance for monitoring IS by assessing RNVUs.

Comparison of Renal Adverse Events Between Intravitreal Anti-Vascular Endothelial Growth Factor Agents: A Meta-Analysis

PURPOSE

To compare the risk of renal adverse events, particularly acute kidney injury (AKI), between intravitreal anti-vascular endothelial growth factor (anti-VEGF) agents.

DESIGN

Meta-analysis.

METHODS

A systematic literature search was conducted on Ovid Medline, Embase, and the Cochrane Library for randomized controlled trials (RCTs) published from January 2005 to February 2024 involving adult patients receiving anti-VEGF intravitreal injections for age-related macular degeneration, diabetic macular edema, and macular edema secondary to retinal vein occlusion. The primary outcome was the comparative risk of AKI between anti-VEGF agents and sham injections. Secondary outcomes involved other renal adverse events. Subgroup analyses were conducted by specific disease indications. A random-effects model was used for meta-analysis to estimate risk ratios (RRs) and their 95% confidence intervals, with a P value of <.05 representing statistical significance. Risk of bias was assessed using the Cochrane Risk of Bias 2 (ROB2) tool, and the certainty of evidence was evaluated through the Cochrane Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework.

RESULTS

A total of 10,031 eyes from 11 RCTs were included. No significant differences were found in the risk of acute or chronic renal conditions, obstructive uropathies, neoplasia, or infectious processes between anti-VEGF agents and sham therapy. AKI was reported in 5.4% (n = 10/185) of patients treated with bevacizumab, 1.3% (n = 6/456) with sham, 1.0% (n = 48/4724) with aflibercept, 0.8% (n = 15/1929) with faricimab, 0.5% (n = 5/1098) with brolucizumab, and 0.3% (n = 5/1639) with ranibizumab. No significant differences in AKI risk were observed between any of the anti-VEGF agents and sham (P > .05 for all comparisons). However, there was an increased risk of patient-reported symptoms with 1.25 mg bevacizumab compared to 2 mg aflibercept (RR = 3.26, 95% CI = 1.07-9.93, P = .04), driven primarily by reports of hematuria: 4.3% (bevacizumab), 0.7% (sham), 0.2% (aflibercept), 0.1% (faricimab), and 0.1% (ranibizumab).

CONCLUSIONS

US Food and Drug Administration (FDA)-approved intravitreal anti-VEGF agents do not significantly increase the risk of AKI compared to sham injections. Nevertheless, variations in patient-reported renal symptoms were observed across different anti-VEGF drugs. These variations were influenced primarily by differences in hematuria events, which may be a result of differential systemic absorption by these agents. These results underscore the importance of continuous monitoring and pharmacovigilance.

Diabetic retinopathy features in lund MetS rats

The Lund MetS rat (BBDR.cg-Leprdb/db.cp/LundRj) is a novel animal model that has a congenic leptin receptor deficiency (LepR-/-) and males exhibit a variety of metabolic abnormalities mimicking the human metabolic syndrome, including hyperglycemia, dyslipidemia, severe obesity, and a type 2 diabetes-like condition from 14 weeks of age. However, whether Lund MetS rats (LM rats) develop diabetic retinopathy is still unknown. The purpose is to investigate the features of diabetic retinopathy in this model. In this study, male LM rats aged 15 and 30 weeks were analyzed for pathological retinal changes, including vasculopathy, inflammation, reactive gliosis, oxidative stress, and neurodegeneration features on the retinas by histological, immunohistochemical, and gene and protein expression analysis. Compared with the non-diabetic LM rats, diabetic LM rats, mainly at 30 weeks of age, had a decrease in retinal thickness and loss of retinal ganglion cells and photoreceptors, indicating retinal neurodegeneration. They also presented an increase in VEGF-A expression, Endra, Icam-1, Vcam-1, and Endrb vascular genes, and albumin suggesting neurovascular unit dysfunction. Furthermore, retinas presented reactive gliosis and infiltration of microglia, TNF-α-positive vessels and expressed elevated levels of inflammatory genes Tnf-α, IL-18 and IL-6, and oxidative stress markers Sod2 and 8-hydroxy-2-deoxyguanosine (8-OHdG). Our results suggest that diabetic LM rats reproduce the early neurodegenerative and altered neuro-vascular features that also occur in the human diabetic eye.

Predictors of Peripheral Retinal Non-Perfusion in Clinically Significant Diabetic Macular Edema

Background/Objectives: Diabetic macular edema (DME) is a significant cause of vision loss. The development of peripheral non-perfusion (PNP) might be associated with the natural course, severity, and treatment of DME. The present study seeks to understand the predictive power of central macular changes and clinico-demographic features for PNP in patients with clinically significant DME. Methods: A prospective study using contemporaneous multi-modal retinal imaging was performed. In total, 48 eyes with DME from 33 patients were enrolled. Demographic, clinical history, laboratory measures, ultrawide field photography, fluorescein angiography, optical coherence tomography (OCT), and OCT angiography results were acquired. Anatomic and vascular features of the central macula and peripheral retina were quantified from retinal images. Separate (generalized) linear mixed models were used to assess differences between PNP present and absent groups. Mixed effects logistic regression was used to assess which features have predictive power for PNP. Results: Variables with significant differences between eyes with and without PNP were insulin use (p = 0.0001), PRP treatment (p = 0.0003), and diffuse fluorescein leakage (p = 0.013). Importantly, there were no significant differences for any of the macular vascular metrics including vessel density (p = 0.15) and foveal avascular zone (FAZ) area (p = 0.58 and capillary tortuosity (p = 0.55). Features with significant predictive power (all p < 0.001) were subretinal fluid, FAZ eccentricity, ellipsoid zone disruption, past anti-VEGF therapy, insulin use, and no ischemic heart disease. Conclusions: In the setting of DME, macular vascular changes did not predict the presence of PNP. Therefore, in order to detect peripheral non-perfusion in DME, our results implicate the importance of peripheral retinal vascular imaging.

Resolution of Angiographic Macular Leakage with Faricimab versus Aflibercept in Patients with Diabetic Macular Edema in YOSEMITE/RHINE

PURPOSE

To evaluate if dual angiopoietin-2 (Ang-2)/VEGF-A inhibition with faricimab resulted in greater macular leakage resolution versus aflibercept in patients with diabetic macular edema (DME).

DESIGN

Post hoc analysis of macular leakage assessments prespecified in the YOSEMITE/RHINE (NCT03622580/NCT03622593) phase III trials.

PARTICIPANTS

Adults with visual acuity loss due to center-involving DME.

METHODS

Patients were randomized 1:1:1 to faricimab 6.0 mg every 8 weeks (Q8W), faricimab 6.0 mg according to a personalized treat-and-extend (T&E)-based regimen, or aflibercept 2.0 mg Q8W. This analysis included the first 16 weeks (head-to-head dosing period) when all patients received assigned study drug every 4 weeks (Q4W); patients were assessed 4 weeks after receiving 4 doses of assigned study drug Q4W.

MAIN OUTCOME MEASURES

Macular leakage area on fluorescein angiography assessed by a reading center; proportion of patients with resolution of macular leakage (defined as macular leakage area 0-1 mm2) and high macular leakage (defined as macular leakage area ≥10 mm2) at baseline and week 16; and the proportion of faricimab T&E patients receiving Q16W dosing at week 52 among those with resolution of and high macular leakage at week 16.

RESULTS

Among patients with macular leakage data available at baseline, there were 1216 patients in the pooled faricimab (Q8W + T&E) arms and 593 patients in the aflibercept arm. Baseline median macular leakage area was similar between the faricimab (24.6 mm2) and aflibercept arms (25.6 mm2). At week 16, median macular leakage area was 3.6 mm2 with faricimab versus 7.6 mm2 with aflibercept (nominal P < 0.0001). More faricimab-treated patients (28%) achieved resolution of macular leakage versus aflibercept at week 16 (15%; nominal P < 0.0001). In the faricimab T&E arm, 63% of patients with resolution of macular leakage and 45% of patients with high macular leakage at week 16 achieved Q16W dosing at week 52 (nominal P < 0.01).

CONCLUSIONS

Faricimab demonstrated greater macular leakage resolution versus aflibercept during head-to-head dosing. These findings suggest that dual Ang-2/VEGF-A inhibition promotes vascular stability beyond VEGF inhibition alone, supporting faricimab's potential to offer greater disease control and extend durability for patients with DME.

FINANCIAL DISCLOSURE(S)

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

Management of treatment-naïve diabetic macular edema patients: Review of real-world clinical data

The high prevalence of Diabetic macular edema (DME) is a real global health problem. Its complex pathophysiology involves different pathways. Over the last decade, the introduction of intravitreal treatments has dramatically changed the management and prognosis of DME. Among the different treatment options, inhibitors of vascular endothelial growth factor (anti-VEGF) and intravitreal steroids implants represent the first-line therapy of DME. We conducted a review of electronic databases to compile the available evidence about the clinical management of DME in a clinical setting, with a special focus on treatment-naïve patients. Anti-VEGF therapies represent a valuable option for treating DME patients. However, many patients do not respond properly to this treatment and, due to its administration regimen, many patients receive suboptimal treatment in real life. Current evidence demonstrated that in patients with DME, DEX-i improved significantly both anatomic and visual outcomes. Besides eyes with insufficient anti-VEGF respond or recalcitrant DME cases, DEX-i can be effectively and safely used in treatment-naïve DME patients as first line therapy. DEX-i may be considered first line therapy in different clinical scenarios, such as DME eyes with a greater inflammatory component, patients with cardiovascular events, vitrectomized eyes, or those requiring cataract surgery. In conclusion, there are still many points for improvement pending in the clinical management of the patient with DME. Since DME treatment must follow a patient-tailored approach, selecting the best therapeutic approach for each patient requires a good understanding of the pathophysiology of DME.

Association of Various Optical Coherence Tomographic Patterns of Diabetic Macular Edema With Central Subfield Thickness and Visual Acuity: A Cross-Sectional Observational Study

Introduction Diabetic macular edema (DME) is the most common and vision-threatening complication in diabetic patients with diabetic retinopathy (DR), especially in those with Type 2 diabetes mellitus. Optical coherence tomography (OCT) is a reliable tool most commonly used for assessing macular morphology and provides quantitative information on the macula. OCT also examines the outer retinal layers, which can predict visual outcomes. Thus, our study aims to identify the association of various OCT-detected DME morphological patterns with central subfield thickness (CST) and visual acuity. Materials and methods This is a cross-sectional observational study of 50 patients with DME detected on OCT who visited the Ophthalmology Department of Saveetha Medical College and Hospitals for a period of six months, from November 2023 to April 2024. A complete ocular examination, including best corrected visual acuity, scored with the logMAR scale, anterior segment examination, and fundus biomicroscopy using 90D and 78D lenses, was performed. Early Treatment of Diabetic Retinopathy Study (ETDRS) grading of DR into mild to very severe non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR) was noted. Spectral-domain OCT was used to diagnose DME. The CST was measured, and DME was classified into four patterns: sponge-like retinal swelling (SLRS), cystoid macular edema (CME), subretinal fluid (SRF), and posterior hyaloid traction (PHT). Results In the present study, males represented 60%, and females represented 40%. The mean age of the patients was 58.07 ± 6.80 years, with a mean duration of diabetes of 11.91 ± 5.14 years. Of the 50 patients with 100 eyes, only 60 eyes showed DME on OCT. CME was the most common morphological pattern (37%), while the least common pattern was PHT (10%). No significant association was found between a specific morphological pattern and control of diabetes. The most common pattern observed was SLRS in moderate NPDR, CME in severe NPDR, SRF in very severe NPDR, and PHT in PDR. Very severe NPDR patients showed all patterns of DME, and the PHT pattern was observed only in very severe NPDR and PDR. The highest mean CST was observed in the very severe NPDR stage, and the least was in the moderate NPDR stage. The mean CST was highest in SRF patterns and lowest in SLRS patterns. The best mean visual acuity was observed in the SLRS pattern, while the worst mean visual acuity was observed in the SRF pattern, followed by the PHT pattern. Conclusion Our study highlights the importance of OCT in patients with diabetes, as OCT patterns of DME are critical for predicting visual outcomes in DR. Severe grades of DR are usually associated with SRF and PHT patterns. Since patients with SRF and PHT patterns have the worst visual outcomes, these patients, upon identification, need to be counseled about their poor visual prognosis. Those with less severe DR should be closely monitored and advised on effective diabetes control to prevent progression and protect their vision.

A Glucose-Responsive Hydrogel Inhibits Primary and Secondary BRB Injury for Retinal Microenvironment Remodeling in Diabetic Retinopathy

Current diabetic retinopathy (DR) treatment involves blood glucose regulation combined with laser photocoagulation or intravitreal injection of vascular endothelial growth factor (VEGF) antibodies. However, due to the complex pathogenesis and cross-interference of multiple biochemical pathways, these interventions cannot block disease progression. Recognizing the critical role of the retinal microenvironment (RME) in DR, it is hypothesized that reshaping the RME by simultaneously inhibiting primary and secondary blood-retinal barrier (BRB) injury can attenuate DR. For this, a glucose-responsive hydrogel named Cu-PEI/siMyD88@GEMA-Con A (CSGC) is developed that effectively delivers Cu-PEI/siMyD88 nanoparticles (NPs) to the retinal pigment epithelium (RPE). The Cu-PEI NPs act as antioxidant enzymes, scavenging ROS and inhibiting RPE pyroptosis, ultimately blocking primary BRB injury by reducing microglial activation and Th1 differentiation. Simultaneously, MyD88 expression silence in combination with the Cu-PEI NPs decreases IL-18 production, synergistically reduces VEGF levels, and enhances tight junction proteins expression, thus blocking secondary BRB injury. In summary, via remodeling the RME, the CSGC hydrogel has the potential to disrupt the detrimental cycle of cross-interference between primary and secondary BRB injury, providing a promising therapeutic strategy for DR.

Comparing the efficacy of dexamethasone implant and anti-VEGF for the treatment of macular edema: A systematic review and meta-analysis

OBJECTIVES

To evaluate the clinical efficacy of dexamethasone (DEX) implant, for the treatment of macular edema (ME) caused by retinal vein occlusion (RVO) and diabetic retinopathy (DR) through a systematic review and meta-analysis.

METHODS

The PubMed, Embase and Cochrane Library databases were comprehensively searched from inception to November 21, 2022, for studies evaluating the clinical efficacy of DEX implant for patients with retinal vein occlusion macular edema (RVO-ME) or diabetic macular edema (DME). Randomized controlled trials (RCTs) published in English were considered eligible. The Cochrane Collaboration tool was applied to assess the risk of bias in each study. Effect estimates with 95% confidence intervals (CIs) were pooled using the random effects model. We also conducted subgroup analyses to explore the sources of heterogeneity and the stability of the results.

RESULTS

This meta-analysis included 8 RCTs (RVO-ME [n = 2] and DME [n = 6]) assessing a total of 336 eyes. Compared with anti-VEGF therapy, DEX implant treatment achieved superior outcomes in terms of best corrected visual acuity (BCVA) (mean difference [MD] = -3.68 ([95% CI, -6.11 to -1.25], P = 0.003), and no heterogeneity was observed (P = 0.43, I2 = 0%). DEX implant treatment also significantly reduced central macular thickness (CMT) compared with anti-VEGF treatment (MD = -31.32 [95% CI, -57.92 to -4.72], P = 0.02), and there was a high level of heterogeneity between trials (P = 0.04, I2 = 54%). In terms of severe adverse events, DEX implant treatment had a higher risk of elevated intraocular pressure than anti-VEGF therapy (RR = 6.98; 95% CI: 2.16 to 22.50; P = 0.001), and there was no significant difference in cataract progression between the two groups (RR = 1.83; 95% CI: 0.63 to 5.27, P = 0.31).

CONCLUSIONS

Compared with anti-VEGF therapy, DEX implant treatment is more effective in improving BCVA and reducing ME. Additionally, DEX implant treatment has a higher risk of elevated intraocular pressure. Due to the small number of studies and the short follow-up period, the results should be interpreted with caution. The long-term effects of the two treatments need to be further determined.

TRIAL REGISTRATION

Prospero Registration Number CRD42021243185.

Exploring the role of Müller cells-derived exosomes in diabetic retinopathy

Exosomes are nanosized vesicles that have been reported as cargo-delivering vehicles between cells. Müller cells play a crucial role in the pathogenesis of diabetic retinopathy (DR). Activated Müller cells in the diabetic retina mediate disruption of barrier integrity and neovascularization. Endothelial cells constitute the inner blood-retinal barrier (BRB). Herein, we aim to evaluate the effect of Müller cell-derived exosomes on endothelial cell viability and barrier function under normal and hyperglycemic conditions. Müller cell-derived exosomes were isolated and characterized using Western blotting, nanoparticle tracking, and electron microscopy. The uptake of Müller cells-derived exosomes by the human retinal endothelial cells (HRECs) was monitored by labeling exosomes with PKH67. Endothelial cell vitality after treatment by exosomes under normo- and hypoglycemic conditions was checked by MTT assay and Western blot for apoptotic proteins. The barrier function of HRECs was evaluated by analysis of ZO-1 and transcellular electrical resistance (TER) using ECIS. Additionally, intracellular Ca+2 in HRECs was assessed by spectrofluorimetry. Analysis of the isolated exosomes showed a non-significant change in the number of exosomes isolated from both normal and hyperglycemic condition media, however, the average size of exosomes isolated from the hyperglycemic group showed a significant rise when compared to that of the normoglycemic group. Müller cells derived exosomes from hyperglycemic condition media markedly reduced HRECs cell count, increased caspase-3 and Annexin V, decreased ZO-1 levels and TER, and increased intracellular Ca+ when compared to other groups. However, treatment of HRECs under hyperglycemia with normo-glycemic Müller cells-derived exosomes significantly decreased cell death, preserved cellular integrity and barrier function, and reduced intracellular Ca+2. Collectively, Müller cell-derived exosomes play a remarkable role in the pathological changes associated with hyperglycemia-induced inner barrier dysfunction in DR. Further in vivo research will help in understanding the role of exosomes as therapeutic targets and/or delivery systems for DR.

Retinal vascular morphological characteristics in diabetic retinopathy: an artificial intelligence study using a transfer learning system to analyze ultra-wide field images

AIM

To investigate the morphological characteristics of retinal vessels in patients with different severity of diabetic retinopathy (DR) and in patients with or without diabetic macular edema (DME).

METHODS

The 239 eyes of DR patients and 100 eyes of healthy individuals were recruited for the study. The severity of DR patients was graded as mild, moderate and severe non-proliferative diabetic retinopathy (NPDR) according to the international clinical diabetic retinopathy (ICDR) disease severity scale classification, and retinal vascular morphology was quantitatively analyzed in ultra-wide field images using RU-net and transfer learning methods. The presence of DME was determined by optical coherence tomography (OCT), and differences in vascular morphological characteristics were compared between patients with and without DME.

RESULTS

Retinal vessel segmentation using RU-net and transfer learning system had an accuracy of 99% and a Dice metric of 0.76. Compared with the healthy group, the DR group had smaller vessel angles (33.68±3.01 vs 37.78±1.60), smaller fractal dimension (Df) values (1.33±0.05 vs 1.41±0.03), less vessel density (1.12±0.44 vs 2.09±0.36) and fewer vascular branches (206.1±88.8 vs 396.5±91.3), all P<0.001. As the severity of DR increased, Df values decreased, P=0.031. No significant difference between the DME and non-DME groups were observed in vascular morphological characteristics.

CONCLUSION

In this study, an artificial intelligence retinal vessel segmentation system is used with 99% accuracy, thus providing with relatively satisfactory performance in the evaluation of quantitative vascular morphology. DR patients have a tendency of vascular occlusion and dropout. The presence of DME does not compromise the integral retinal vascular pattern.

Switching to an Intravitreal Dexamethasone Implant after Intravitreal Anti-VEGF Therapy for Diabetic Macular Edema: A Review

Among working-age people, diabetic retinopathy and diabetic macular edema are currently considered the main causes of blindness. Nowadays, intravitreal injections are widely acknowledged as a significant milestone in ophthalmology, especially for the treatment of several retinal diseases, including diabetic macular edema. In particular, anti-vascular endothelial growth factor (VEGF) agents are typically the first line of treatment; however, monthly injections are required, at least, during the loading dosage. Notably, an intravitreal 0.7 mg dexamethasone (DEX) implant (Ozurdex®, AbbVie Inc., North Chicago, IL, USA) is considered a legitimate substitute treatment for diabetic eyes that have not responded to anti-VEGF treatment. In fact, clinical trials and real-life studies have demonstrated the effectiveness and safety of an intravitreal DEX implant in treating such conditions over a period of three to six months. For this reason, wisely selecting diabetic patients might be crucial to decreasing the load of injections in clinics and hospitals. The purpose of this review is to analyze the available scientific literature to highlight the benefits, efficacy, and clinical criteria for choosing whether to switch from intravitreal anti-VEGF therapy to an intravitreal DEX implant in diabetic macular edema.

Aflibercept Off-Target Effects in Diabetic Macular Edema: An In Silico Modeling Approach

Intravitreal aflibercept injection (IAI) is a treatment for diabetic macular edema (DME), but its mechanism of action (MoA) has not been completely elucidated. Here, we aimed to explore IAI's MoA and its multi-target nature in DME pathophysiology with an in silico (computer simulation) disease model. We used the Therapeutic Performance Mapping System (Anaxomics Biotech property) to generate mathematical models based on the available scientific knowledge at the time of the study, describing the relationship between the modulation of vascular endothelial growth factor receptors (VEGFRs) by IAI and DME pathophysiological processes. We also undertook an enrichment analysis to explore the processes modulated by IAI, visualized the effectors' predicted protein activity, and specifically evaluated the role of VEGFR1 pathway inhibition on DME treatment. The models simulated the potential pathophysiology of DME and the likely IAI's MoA by inhibiting VEGFR1 and VEGFR2 signaling. The action of IAI through both signaling pathways modulated the identified pathophysiological processes associated with DME, with the strongest effects in angiogenesis, blood-retinal barrier alteration and permeability, and inflammation. VEGFR1 inhibition was essential to modulate inflammatory protein effectors. Given the role of VEGFR1 signaling on the modulation of inflammatory-related pathways, IAI may offer therapeutic advantages for DME through sustained VEGFR1 pathway inhibition.

Efficacy and safety of intravitreal injections of conbercept for the treatment of idiopathic choroidal neovascularization

BACKGROUND

To determine the efficacy and safety of intravitreally injected conbercept, a vascular endothelial growth factor receptor fusion protein, for the treatment of idiopathic choroidal neovascularization (ICNV).

METHODS

This retrospective study analyzed outcomes in 40 patients (40 eyes) with ICNV who received intravitreal injections of conbercept 0.5 mg (0.05 ml) and were followed up for at least 12 months. All patients underwent full ophthalmic examinations, including best-corrected vision acuity (BCVA), intraocular pressure (IOP), slit-lamp examination, color fundus photography, optical coherence tomography angiography, multifocal electroretinogram, and fundus fluorescence angiography, if necessary, at baseline and after 1, 3, 6, and 12 months. BCVA, macular central retinal thickness (CRT), IOP, CNV blood flow area, thickness of the CNV-pigment epithelial detachment complex, thickness of the retinal nerve fiber layer (RNFL), and the first positive peak (P1) amplitude density in ring 1 before and after treatment were compared.

RESULTS

Mean baseline BCVA (logMAR), CRT, CNV blood flow area, and CNV-pigment epithelial detachment complex thickness were significantly lower 1, 3, 6, and 12 months after than before conbercept treatment (P < 0.05 each). IOP and baseline RNFL thickness were unaffected by conbercept treatment. P1 amplitude density was significantly higher 1, 3, 6, and 12 months after than before conbercept treatment (P < 0.05 each). None of the 40 eyes showed obvious ocular adverse reactions, such as endophthalmitis, glaucoma, cataract progression, and retinal detachment, and none of the patients experienced systemic adverse events, such as cardiovascular and cerebrovascular accidents.

CONCLUSIONS

Intravitreal injection of conbercept is beneficial to eyes with ICNV, inducing the recovery of macular structure and function and improving BCVA, while not damaging the neuroretina. Intravitreal conbercept is safe and effective for the treatment of ICNV.

Innovations in Diabetic Macular Edema Management: A Comprehensive Review of Automated Quantification and Anti-vascular Endothelial Growth Factor Intervention

Diabetic macular edema (DME) poses a significant threat to the vision and quality of life of individuals with diabetes. This comprehensive review explores recent advancements in DME management, focusing on integrating automated quantification techniques and anti-vascular endothelial growth factor (anti-VEGF) interventions. The review begins with an overview of DME, emphasizing its prevalence, impact on diabetic patients, and current challenges in management. It then delves into the potential of automated quantification, leveraging machine learning and artificial intelligence to improve early detection and monitoring. Concurrently, the role of anti-VEGF therapies in addressing the underlying vascular abnormalities in DME is scrutinized. The review synthesizes vital findings, highlighting the implications for the future of DME management. Promising outcomes from recent clinical trials and case studies are discussed, providing insights into the evolving landscape of personalized medicine approaches. The conclusion underscores the transformative potential of these innovations, calling for continued research, collaboration, and integration of these advancements into clinical practice. This review aims to serve as a roadmap for researchers, clinicians, and industry stakeholders, fostering a collective effort to enhance the precision and efficacy of DME management.

A Review on Diabetic Retinopathy

Diabetic retinopathy is a well-recognised microvascular complication of diabetes and is among the leading cause of blindness all over the world. Over the last decade, there have been advances in the diagnosis of diabetic retinopathy and diabetic macular edema. At the same time, newer therapies for the management of diabetic retinopathy have evolved. As a result of these advances, a decline in severe vision loss due to diabetes has been witnessed in some developing countries. However, there is a steady increase in the number of people affected with diabetes, and is expected to rise further in the coming years. Therefore, it is prudent to identify diabetic retinopathy, and timely intervention is needed to decrease the burden of severe vision loss. An effort has been made to review all the existing knowledge regarding diabetic retinopathy in this article and summarize the present treatment options for diabetic retinopathy.

Acute Kidney Injury from Intravitreal Anti-vascular Endothelial Growth Factor Drugs: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Several observational studies have reported acute kidney injury from intravitreal anti-vascular endothelial growth factor (anti-VEGF) drugs for retinal diseases. However, systematic reviews and meta-analyses of randomized controlled trials on this critical topic are scant.

OBJECTIVE

To evaluate acute kidney injury risk associated with intravitreal anti-VEGF drugs in patients with retinal diseases.

METHODS

We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials on 12 July, 2023, and included randomized controlled trials reporting acute kidney injury between anti-VEGF drugs (e.g., aflibercept, bevacizumab, brolucizumab, and ranibizumab) and controls for retinal diseases (e.g., age-related macular degeneration, polypoidal choroidal vasculopathy, diabetic retinopathy/diabetic macular edema, retinal vein occlusion, and myopic choroidal neovascularization). Data were synthesized by a fixed-effects model for pooling odds ratios (ORs) using the Peto method.

RESULTS

We included 13 randomized controlled trials (four and nine trials for aflibercept and ranibizumab, respectively) with a total of 4282 participants. The meta-analysis indicated intravitreal anti-VEGF drugs did not increase the acute kidney injury risk, compared with controls (odds ratio [OR]: 1.00, 95% confidence interval [CI] 0.49-2.04, I2: 0%), and no differences in the acute kidney injury risk were observed between different anti-VEGF drugs (OR: 1.10, 95% CI 0.27-4.43, I2: 0% for aflibercept; OR: 0.97, 95% CI 0.42-2.22, I2: 0% for ranibizumab) and between different retinal diseases (OR: 4.61, 95% CI 0.07-284.13, I2: not applicable for age-related macular degeneration; OR: 0.90, 95% CI 0.42-1.93, I2: 0% for diabetic retinopathy/diabetic macular edema; OR: 1.57, 95% CI 0.16-15.88, I2: 0% for retinal vein occlusion).

CONCLUSIONS

Intravitreal anti-VEGF drugs were not associated with an acute kidney injury risk, regardless of which anti-VEGF drugs (aflibercept or ranibizumab) or retinal diseases (age-related macular degeneration, diabetic retinopathy/diabetic macular edema, or retinal vein occlusion) were involved.

SYSTEMATIC REVIEW PROTOCOL REGISTRATION

PROSPERO CRD42021267854.

Fluocinolone Acetonide Implant Injected 1 Month after Dexamethasone Implant for Diabetic Macular Oedema: the ILUVI1MOIS Study

INTRODUCTION

The aim of this study was to assess the efficacy and safety of fluocinolone acetonide implant (FAci) injected 1 month after the last dexamethasone intravitreal implant (DEXi) in chronic diabetic macular oedema (DME) patients.

METHODS

Retrospective multicentric study conducted in pseudophakic patients with chronic DME frequently treated with dexamethasone intravitreal implant (DEXi; time to DME recurrence ≤ 6 months), receiving FAci 1 month after the last DEXi, with at least a 6-month follow-up. Best-corrected visual acuity (BCVA), central macular thickness (CMT) on optical coherence tomography, intraocular pressure (IOP) and additional treatments were assessed on the day of FAci injection (M0), 1 (M1) and 3 months (M3) later and then every 3 months.

RESULTS

A total of 41 eyes from 34 patients were included. At M0, patients' mean age was 68.7 ± 9.8 years, the mean DME duration was 63.9 ± 22.9 months, the mean interval between two DEXi was 14.2 ± 3.3 weeks. M12 data were available for 71% of patients. At baseline, the mean BCVA, CMT and IOP were 63.2 ± 16.6 letters, 299.4 ± 103.3 µm, and 16.2 ± 4.5 mmHg, respectively, and remained stable during the follow-up. At M12, 14% of patients required additional intravitreal treatments.

CONCLUSION

In pseudophakic patients with chronic DME showing good response to DEXi but requiring repeated injections every < 6 months, switching to FAci 1 month after the last DEXi was effective and safe. Further prospective randomized controlled studies are needed to confirm these findings, and to determine the best interval between the last DEXi and the first FAci.

Comparative analysis of co-culture and monoculture models in simulating diabetic neurovascular dysfunction: insights into diabetic retinopathy

Background

Interaction between retinal vascular endothelial cells and neurons plays a critical role in the pathogenesis of diabetic retinopathy (DR). This study aims to compare an in vitro model over a monoculture model to simulate the neurovascular coupling under the hyperglycemic microenvironment of diabetes.

Methods

Rat retinal vascular endothelial cells (RRMECs) and ganglion cells (RGCs) were seeded mono- or co-cultured in a normal (NG, 5.5 mM) and high (HG, 75 mM) glucose concentrations culture medium. Cell viability was detected by the cell counting kit-8 (CCK-8) assay. The ability of migration and lumen formation of RRMECs were determined by scratch wound, transwell migration, and lumen formation assays. The apoptosis index of cells was calculated and detected by propidium iodide (PI)/Hoechst staining. Quantitative and morphological analysis of RGCs was performed through the labeling of RGCs by brain-specific homeobox/POU domain protein 3A (BRN3A) and anti-beta-III tubulin (TUJ1). The gene and protein expression levels of occludin (OCLN) and zonula occludens-1 (ZO-1) were evaluated by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay.

Results

The viability, migration, and lumen formation abilities of RRMECs in the HG group significantly increased (P<0.05) in both mono- and co-culture models. Migration and lumen formation abilities of RRMECs in the co-culture with HG were lower than that in the monoculture group (P<0.05). The viability of RGCs cells with HG significantly decreased in both mono- and co-culture models (Pmono<0.001, Pco<0.001), the apoptosis index of RGCs in the co-culture with HG was higher than that in the monoculture (P=0.010). The protein and gene expression of OCLN, and ZO-1 in RRMECs significantly decreased with HG culture medium in both culture models (P<0.05). In the HG group, the protein and gene expression level of the ZO-1 and OCLN of RRMECs significantly decreased in the co-culture model than that in the monoculture model (P<0.05).

Conclusion

Compared with mono cell culture, the established co-culture in vitro system for diabetic neurovascular dysfunction can better stimulate the micro-environment of the retinal neurovascular unit.

Time to fellow eye involvement in patients with unilateral diabetic macular oedema

OBJECTIVE

To examine the time to onset of disease in the fellow eye of patients with unilateral DMO in routine clinical practice and to identify risk factors for development of bilateral DMO.

DESIGN

Retrospective cohort study.

PARTICIPANTS

One hundred forty treatment-naive patients 18 years or older with unilateral DMO presenting to Cole Eye Institute between January 2012 and July 2021.

METHODS

Records of patients with unilateral DMO were reviewed for development of DMO in the fellow eye. Demographic, diabetic, ocular, and systemic characteristics were collected at initial DMO diagnosis date. Bivariate and multivariate analyses were performed and significant factors were modelled using Kaplan-Meier curves.

RESULTS

Fifty patients with conversion to bilateral DMO and 90 patients without conversion were identified. Average time to bilateral DMO was 15.0 ± 15.7 months. 64% of patients converted within 1 year and 90% converted within 3 years. HbA1c (p = 0.003), diabetic retinopathy duration (p = 0.029), and diabetic foot disease (DFD) (p = 0.002) were identified as significant risk factors for conversion. Patients with better visual acuity at time of initial diagnosis and history of panretinal photocoagulation (PRP) (p = 0.044) or focal laser (p = 0.035) in the primary eye were also more likely to convert.

CONCLUSIONS

Participants were most likely to develop fellow eye DMO within the first year after initial DMO diagnosis. In routine clinical practice, poor glycaemic control and DFD were risk factors associated with bilateral eye involvement. Clinicians may consider screening the fellow eye of high-risk individuals at each appointment within the first year of diagnosis.

Longitudinal Quantitative Ultrawide-field Fluorescein Angiography Dynamics in the RUBY Diabetic Macular Edema Study

OBJECTIVE

The purpose of this study was to evaluate the longitudinal change in quantitative ultrawide-field angiographic (UWFA) parameters and correlate them with functional outcomes and spectral domain-OCT metrics.

DESIGN

This study is a post hoc analysis of the phase II RUBY study: a prospective, randomized trial of patients with diabetic macular edema (DME) treated with either intravitreal aflibercept injection (IAI) or combined IAI/nesvacumab (antiangiopoietin 2 mAb).

SUBJECTS

Subjects with DME that underwent UWFA across all treatment groups (n = 44).

METHODS

A machine learning-enabled feature extraction system generated panretinal quantitative UWFA metrics, including leakage, ischemia, and microaneurysm (MA) burden. Zonal assessments were performed corresponding to the macula, midperiphery, and far periphery.

MAIN OUTCOME MEASURES

Changes in ischemic area and index (proportion of nonperfusion in analyzable retina), leakage area and index (proportion of leakage in analyzable retina), and MA count at baseline, week 12, week 24, and week 36 were analyzed. Spectral-domain-OCT quantitative metrics, such as central subfield thickness, ellipsoid zone (EZ) integrity parameters, intraretinal fluid (IRF) volume, and subretinal fluid (SRF) volume were extracted via a machine learning-enhanced OCT feature extraction platform and analyzed. Additionally, the effect of these changes on best-corrected visual acuity (BCVA) was evaluated.

RESULTS

Mean panretinal leakage index, zonal leakage area, and panretinal MA count improved significantly between baseline and week 36. Panretinal ischemic index decreased between baseline and week 36, with some aspects showing significant improvement. Mean BCVA significantly improved from baseline to week 36. There was a significant inverse correlation between change in BCVA and change in macular leakage area. A direct correlation was observed between both baseline macular leakage area and panretinal leakage index with IRF volume, SRF volume, and EZ disruption on OCT.

CONCLUSIONS

Assessment of UWFA parameters demonstrates a significant improvement in panretinal leakage index, leakage area, and MA burden in eyes treated with IAI with or without nesvacumab. A numeric reduction in panretinal ischemic index and area was noted. The analysis also shows the critical association of leakage with visual and OCT features. This highlights the potential role of UWFA in disease burden assessment, with leakage parameters serving as a primary end point.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Oxidative Stress, Inflammatory, Angiogenic, and Apoptotic molecules in Proliferative Diabetic Retinopathy and Diabetic Macular Edema Patients

The aim of this study is to evaluate molecules involved in oxidative stress (OS), inflammation, angiogenesis, and apoptosis, and discern which of these are more likely to be implicated in proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME) by investigating the correlation between them in the plasma (PLS) and vitreous body (VIT), as well as examining data obtained from ophthalmological examinations. Type 2 diabetic (T2DM) patients with PDR/DME (PDRG/DMEG; n = 112) and non-DM subjects as the surrogate controls (SCG n = 48) were selected according to the inclusion/exclusion criteria and programming for vitrectomy, either due to having PDR/DME or macular hole (MH)/epiretinal membrane (ERM)/rhegmatogenous retinal detachment. Blood samples were collected and processed to determine the glycemic profile, total cholesterol, and C reactive protein, as well as the malondialdehyde (MDA), 4-hydroxynonenal (4HNE), superoxide dismutase (SOD), and catalase (CAT) levels and total antioxidant capacity (TAC). In addition, interleukin 6 (IL6), vascular endothelial growth factor (VEGF), and caspase 3 (CAS3) were assayed. The VITs were collected and processed to measure the expression levels of all the abovementioned molecules. Statistical analyses were conducted using the R Core Team (2022) program, including group comparisons and correlation analyses. Compared with the SCG, our findings support the presence of molecules involved in OS, inflammation, angiogenesis, and apoptosis in the PLS and VIT samples from T2DM. In PLS from PDRG, there was a decrease in the antioxidant load (p < 0.001) and an increase in pro-angiogenic molecules (p < 0.001), but an increase in pro-oxidants (p < 0.001) and a decline in antioxidants (p < 0.001) intravitreally. In PLS from DMEG, pro-oxidants and pro-inflammatory molecules were augmented (p < 0.001) and the antioxidant capacity diminished (p < 0.001), but the pro-oxidants increased (p < 0.001) and antioxidants decreased (p < 0.001) intravitreally. Furthermore, we found a positive correlation between the PLS-CAT and the VIT-SOD levels (rho = 0.5; p < 0.01) in PDRG, and a negative correlation between the PSD-4HNE and the VIT-TAC levels (rho = 0.5; p < 0.01) in DMEG. Integrative data of retinal imaging variables showed a positive correlation between the central subfield foveal thickness (CSFT) and the VIT-SOD levels (rho = 0.5; p < 0.01), and a negative correlation between the CSFT and the VIT-4HNE levels (rho = 0.4; p < 0.01) in PDRG. In DMEG, the CSFT displayed a negative correlation with the VIT-CAT (rho = 0.5; p < 0.01). Exploring the relationship of the abovementioned potential biomarkers between PLS and VIT may help detecting early molecular changes in PDR/DME, which can be used to identify patients at high risk of progression, as well as to monitor therapeutic outcomes in the diabetic retina.

Spontaneous Resolution of Tractional Retinal Detachment in a Type II Diabetic Patient

A 43 years old male with diabetes type II was under treatment for diabetic retinopathy with extramacular tractional retinal detachment (TRD) in the left eye OS. During the follow-up visit, the patient had a drop in vision from 20/25 to 20/60. The TRD was found to have progressed to involve the macula and was threatening the fovea; therefore, vitrectomy was thought to be inevitable. Meanwhile, the patient adopted exercise and tight glycemic control, and during the preoperative evaluation of three months duration, we observed resolution of traction and return of visual acuity to baseline (20/20). In conclusion, spontaneous resolution of TRD is extremely rare. If it occurs, the patient may be spared from undergoing a vitrectomy.

Ferritin But Not Iron Increases in Retina Upon Systemic Iron Overload in Diabetic and Iron-Dextran Injected Mice

Purpose

Iron overload causes oxidative damage in the retina, and it has been involved in the pathogeny of diabetic retinopathy, which is one of the leading causes of blindness in the adult population worldwide. However, how systemic iron enters the retina during diabetes and the role of blood retinal barrier (BRB) in this process remains unclear.

Methods

The db/db mouse, a well-known model of type 2 diabetes, and a model of systemic iron overload induced by iron dextran intraperitoneal injection, were used. Perls staining and mass spectrophotometry were used to study iron content. Western blot and immunohistochemistry of iron handling proteins were performed to study systemic and retinal iron metabolism. BRB function was assessed by analyzing vascular leakage in fundus angiographies, whole retinas, and retinal sections and by studying the status of tight junctions using transmission electron microscopy and Western blot analysis.

Results

Twenty-week-old db/db mice with systemic iron overload presented ferritin overexpression without iron increase in the retina and did not show any sign of BRB breakdown. These findings were also observed in iron dextran-injected mice. In those animals, after BRB breakdown induced by cryopexy, iron entered massively in the retina.

Conclusions

Our results suggested that BRB protects the retina from excessive iron entry in early stages of diabetic retinopathy. Furthermore, ferritin overexpression before iron increase may prepare the retina for a potential BRB breakdown and iron entry from the systemic circulation.

Inflammation and retinal degenerative diseases

Vision is an ability that depends on the precise structure and functioning of the retina. Any kind of stress or injury can disrupt the retinal architecture and leads to vision impairment, vision loss, and blindness. Immune system and immune response function maintain homeostasis in the microenvironment. Several genetic, metabolic, and environmental factors may alter retinal homeostasis, and these events may initiate various inflammatory cascades. The prolonged inflammatory state may contribute to the initiation and development of retinal disorders such as glaucoma, age-related macular degeneration, diabetic retinopathy, and retinitis pigmentosa, which pose a threat to vision. In the current review, we attempted to provide sufficient evidence on the role of inflammation in these retinal disorders. Moreover, this review paves the way to focus on therapeutic targets of the disease, which are found to be promising.

Factors affecting central macular thickness of diabetic macular oedema patients after an induction treatment of intravitreal ranibizumab

OBJECTIVE

Intravitreal ranibizumab is one of the anti-vascular endothelial growth factors used for the treatment of diabetic macular oedema, not always successfully. We aimed to identify the factors affecting the changes of central macular thickness after induction treatment with intravitreal ranibizumab, to predict the treatment effect and facilitate early treatment decisions.

METHODS

Cross-sectional study involving a retrospective record review of diabetic macular oedema patients who received an induction treatment of three monthly 0.5 mg intravitreal ranibizumab injections between 2016 and 2019. Central macular thickness was measured at baseline and 3 months post-treatment. Linear regression was applied to identify the factors associated with the changes of central macular thickness.

RESULTS

A total of 153 diabetic macular oedema patients were involved in this study. Their mean age was 57.5 ± 7.7 years, 54.9% were female. The mean change of central macular thickness from baseline to 3 months after completed induction treatment of intravitreal ranibizumab was 155.5 ± 137.8 μm. Factors significantly associated with changes of central macular thickness were baseline central macular thickness [b = 0.73; 95% (CI): 0.63, 0.84; p = <0.001] and presence of subretinal fluid [b = 35.43; 95% CI: 3.70, 67.16; p = 0.029].

CONCLUSION

Thicker baseline central macular thickness and presence of subretinal fluid were the factors significantly associated with greater changes of central macular thickness in diabetic macular oedema patients after receiving three injections of intravitreal ranibizumab.

Long-Term Outcomes of High-Dose Conbercept Treatment for Myopic Choroidal Neovascularization and Idiopathic Choroidal Neovascularization

INTRODUCTION

The aim of the study was to report 2-year outcomes of intravitreal injection of high-dose conbercept (1 mg 2 + PRN scheme) for subjects with myopic choroidal neovascularization (mCNV) and idiopathic choroidal neovascularization (iCNV) by optical coherence tomography angiography follow-up.

METHODS

A total of 38 subjects (38 eyes) were enrolled in this retrospective study, which were divided into group A (mCNV, 20 subjects, 20 eyes) and group B (iCNV, 18 subjects, 18 eyes). All subjects received 1.0 mg of conbercept intravitreally at diagnosis and again 35 days later. Additional conbercept injection was administered upon findings of decreased best-corrected visual acuity (BCVA); metamorphosis aggravation, macular hemorrhage, or edema; increased central retinal thickness (CRT); or leakage observed by fluorescein angiography. The BCVA, CRT, and CNV areas of the two groups were evaluated at baseline and at 1, 2, 4, 6, 12, and 24 months after surgery.

RESULTS

The BCVA of group A improved from 0.31 ± 0.16 logMAR at baseline to 0.12 ± 0.03 logMAR at the final follow-up (p < 0.001), while in group B the corresponding improvement was from 0.33 ± 0.16 logMAR at baseline to 0.12 ± 0.03 logMAR at the final follow-up (p < 0.001). Visual acuity improved in 17 subjects in group A and 15 in group B, while it remained stable in 3 subjects in each of groups A and B. CRT decreased from 311.83 ± 30.95 μm in group A and 351.17 ± 37.09 μm in group B preoperation to 229.56 ± 5.75 μm and 227.67 ± 4.98 μm at 24-month follow-up, respectively (p < 0.001 in groups A and B). Metamorphopsia was improved in subjects in groups A and B. CNV had disappeared in the two groups at the last postoperative visit. The BCVA, CRT, and CNV areas showed no statistical differences between the two groups at 6-, 12-, and 24-month follow-up (p > 0.05).

CONCLUSION

Intravitreal injection of conbercept (1 mg 2 + PRN scheme) is effective for treating patients with mCNV or iCNV, which can improve and stabilize vision as well as dramatically alleviate metamorphopsia.

Diabetic retinopathy in the pediatric population: Pathophysiology, screening, current and future treatments

Diabetic retinopathy (DR) is a sight threatening complication of diabetes mellitus (DM). The incidence of DR in the pediatric population has increased in the last two decades and it is expected to further rise in the future, following the increase in DM prevalence and obesity in youth. As early stages of the retinal disease are asymptomatic, screening programs are of extreme importance to guarantee a prompt diagnosis and avoid progression to more advanced, sight threatening stages. The management of DR comprises a wide range of actions starting from glycemic control, continuing with systemic and local medical treatments, up to para-surgical and surgical approaches to deal with the more aggressive complications. In this review we will describe the pathophysiology of DR trying to understand all the possible targets for currently available or future treatments. We will briefly consider the impact of screening techniques, screening strategies and their social and economic impact. Finally a large part of the review will be dedicated to medical and surgical treatments for DR including both currently available and under development therapies. Most of the available data in the literature on DR are focused on the adult population. The aim of our work is to provide clinicians and researchers with a comprehensive overview of the state of the art regarding DR in the pediatric population, considering the increasing numbers of this diseases in youth and the inevitable consequences that such a chronic disease could have if poorly managed in children.

Genome-wide association study of the response of patients with diabetic macular edema to intravitreal Anti-VEGF injection

Diabetic macular edema (DME), a complication of diabetes mellitus, is a leading cause of adult-onset blindness worldwide. Recently, intravitreal anti-VEGF injection has been used as a first-line treatment. This study analyzed the association between the genetic profile of patients with DME and their response to treatment. Intravitreal anti-VEGF injections were administered monthly for three months to Korean patients diagnosed with DME, who were classified into two groups depending on whether they responded to anti-VEGF therapy or showed recurrence within six months. Peripheral blood samples were used for genetic analyses. Genome-wide association analysis results sowed that the genes DIRC3 on chromosome 2 (rs16857280, p = 1.2 × 10^-6), SLCO3A1 on chromosome 15 (rs12899055, p = 2.5 × 10^-6), and RAB2A on chromosome 8 (rs2272620, p = 4.6 × 10^-6) were associated with treatment response to intravitreal anti-VEGF injection. SLC35F1, TMEM132D, KIAA0368, HPCAL1, IGF2BP3, SPN2S, COL23A1, and CREB5 were also related to treatment response (p < 5.0 × 10^-5). Using the KEGG pathway analysis, RAB2A and CREB5 were found to be associated with AMPK signaling related to VEGF (p = 0.018). The identified genetic biomarkers can elucidate the factors affecting patient response to intravitreal anti-VEGF injection and help select appropriate therapeutic strategy.

Evaluation of microaneurysms as predictors of therapeutic response to anti-VEGF therapy in patients with DME

Administration of intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapy is the first-line therapy for diabetic macular oedema (DME). However, some patients show no or insufficient response to repeated anti-VEGF injections. Therefore, it is necessary to identify factors that can predict this resistance against anti-VEGF treatment. Presence of microaneurysms (MAs) is a predictor of the development and progression of DME, but its relationship with the treatment response to the anti-VEGF agents is not well known. Therefore, we aimed to elucidate the relationship between the distribution of MAs and the response to anti-VEGF therapy in patients with DME. The number of MAs was measured before anti-VEGF therapy in each region using fluorescein angiography, indocyanine green angiography (IA), and optical coherence tomography angiography. Patients with DME were divided into the responder and non-responder groups after three loading phases. Differences in the distribution of MAs between the groups were investigated. Pre-treatment IA revealed more MAs in the nasal area in the non-responder group than in the responder group (10.7 ± 10.7 and 5.7 ± 5.7, respectively, in the nasal macula) (1.4 ± 2.1 and 0.4 ± 0.7, respectively, in the nasal fovea). Whereas, pre-treatment FA and OCTA could not reveal significantly difference between the groups. Detection of MAs in the nasal macula using pre-treatment IA may indicate resistance to anti-VEGF therapy. We recommend the clinicians confirm the presence of MAs in the nasal macula, as shown by IA, as a predictor of therapeutic response to anti-VEGF therapy in patients with treatment naive DME.

Management of Patients with Diabetic Macular Edema Switched from Dexamethasone Intravitreal Implant to Fluocinolone Acetonide Intravitreal Implant

To assess anatomical and functional outcomes after switching from dexamethasone implant (DEXi) to fluocinolone acetonide implant (FAci) in 113 diabetic macular edema eyes, a multicentric retrospective observational study was conducted. Seventy-five eyes (73.5%) were switched 1−8 weeks after their last DEXi. The mean best-corrected visual acuity improved to 59.8 letters at month 4 and remained stable during the follow-up. The mean central macular thickness (CMT) significantly decreased during the follow-up, with a minimum of 320.9 μm at month 3. The baseline CMT was higher in eyes that received the last DEXi >8 weeks versus <8 weeks before the first FAci (p < 0.021). After FAci injection, additional treatments were needed in 37 (32.7%) eyes. A longer diabetes duration (p = 0.009), a longer time between the last DEXi and the first FAci (p = 0.035), and a high baseline CMT (p = 0.003) were risk factors for additional treatments. The mean intraocular pressure was <19 mmHg at all timepoints, with no difference between eyes receiving the last DEXi ≤8 weeks or >8 weeks before the switch. Switching from DEXi to FAci in DME is effective and safe. A short time between the last DEXi and the first FAci reduced CMT fluctuations and the need for early additional treatments.

Diabetes mellitus associated neurovascular lesions in the retina and brain: A review

Diabetes mellitus (DM) is now recognized as a system-wide, autoimmune, inflammatory, microvascular disorder, which, in the retina and brain results in severe multifocal injury now recognized as a leading cause, world-wide, of progressive vision loss and dementia. To address this problem, resulting primarily from variations in glycemia in the prediabetic and overt diabetic states, it must be realized that, although some of the injury processes associated with diabetes may be system wide, there are varying responses, effector, and repair mechanisms that differ from organ to organ or within varying cell structures. Specifically, within the retina, and similarly within the brain cortex, lesions occur of the "neurovascular unit", comprised of focal microvascular occlusions, inflammatory endothelial and pericyte injury, with small vessel leakage resulting in injury to astrocytes, Müller cells, and microglia, all of which occur with progressive neuronal apoptosis. Such lesions are now recognized to occur before the first microaneurysms are visible to imaging by fundus cameras or before they result in detectable symptoms or signs recognizable to the patient or clinician. Treatments, therefore, which currently are not initiated within the retina until edema develops or there is progression of vascular lesions that define the current staging of retinopathy, and in the brain only after severe signs of cognitive failure. Treatments, therefore are applied relatively late with some reduction in progressive cellular injury but with resultant minimal vision or cognitive improvement. This review article will summarize the multiple inflammatory and remediation processes currently understood to occur in patients with diabetes as well as pre-diabetes and summarize as well the current limitations of methods for assessing the structural and functional alterations within the retina and brain. The goal is to attempt to define future screening, monitoring, and treatment directions that hopefully will prevent progressive injury as well as enable improved repair and attendant function.

Retinal and Choroidal Neovascularization Antivascular Endothelial Growth Factor Treatments: The Role of Gene Therapy

Neovascularization in ocular vessels causes a major disease burden. The most common causes of choroidal neovascularization (CNV) are age-related macular degeneration and diabetic retinopathy, which are the leading causes of irreversible vision loss in the adult population. Vascular endothelial growth factor (VEGF) is critical for the formation of new vessels and is the main regulator in ocular angiogenesis and vascular permeability through its receptors. Laser therapy and antiangiogenic factors have been used for CNV treatment. Bevacizumab, ranibizumab, and aflibercept are commonly used anti-VEGF agents; however, high costs and the need for frequent intraocular injections are major drawbacks of anti-VEGF drugs. Gene therapy, given the potency of one-time treatment and no need for frequent injections offers the real possibility of such a lasting treatment, with fewer adverse effects and higher patient quality of life. Herein, we reviewed the role of gene therapy in the CNV treatment. In addition, we discuss the advantages and challenges of current treatments compared with gene therapy.

Progress and Challenges of Anti-VEGF Agents and Their Sustained-Release Strategies for Retinal Angiogenesis

Currently, the treatment for ocular neovascular diseases, including diabetic macular edema (DME) and age-related macular degeneration (AMD), mainly involves repeated intravitreal injection of anti-vascular endothelial growth factor (VEGF) drugs. Although it can preserve vision, repeated injections are an invasive treatment modality, leading to serious complications and reducing patient adherence to treatment. To reduce the frequency of administration, prolong the time of drug action, and avoid repeated intravitreal injections, the combination of sustained-release materials with anti-VEGF drug therapy has become an emphasis in ophthalmology. In this review, we highlight the current state of anti-VEGF technology, its challenges, and the sustained-release strategies under investigation or being used in clinical practice. Both continuous release and considerable therapeutic effects can be achieved by encapsulating anti-VEGF drugs in sustained-release materials to minimize the number of intravitreal injections. At present, two sustained-release materials are being tested in clinical research, and although basic research shows the strong therapeutic application prospects of extended-release drugs, its challenges mainly involve the discrepancy between the release rates in vitro and the efficiency of the drugs in vivo. Briefly, sustained release of anti-VEGF agents is an advantageous strategy for treating retinal angiogenesis.

Effects of Lycium barbarum L. Polysaccharides on Vascular Retinopathy: An Insight Review

Vascular retinopathy is a pathological change in the retina caused by ocular or systemic vascular diseases that can lead to blurred vision and the risk of blindness. Lycium barbarum polysaccharides (LBPs) are extracted from the fruit of traditional Chinese medicine, L. barbarum. They have strong biological activities, including immune regulation, antioxidation, and neuroprotection, and have been shown to improve vision in numerous studies. At present, there is no systematic literature review of LBPs on vascular retinal prevention and treatment. We review the structural characterization and extraction methods of LBPs, focus on the mechanism and pharmacokinetics of LBPs in improving vascular retinopathy, and discuss the future clinical application and lack of work. LBPs are involved in the regulation of VEGF, Rho/ROCK, PI3K/Akt/mTOR, Nrf2/HO-1, AGEs/RAGE signaling pathways, which can alleviate the occurrence and development of vascular retinal diseases in an inflammatory response, oxidative stress, apoptosis, autophagy, and neuroprotection. LBPs are mainly absorbed by the small intestine and stomach and excreted through urine and feces. Their low bioavailability in vivo has led to the development of novel dosage forms, including multicompartment delivery systems and scaffolds. Data from the literature confirm the medicinal potential of LBPs as a new direction for the prevention and complementary treatment of vascular retinopathy.

Untargeted metabolomic analysis of aqueous humor in diabetic macular edema

BACKGROUND

The mechanism of diabetic macular edema (DME) was explored by comparing the intraocular metabolite profiles of the aqueous humor of patients with DME to those of diabetic patients without DME using untargeted metabolomic analysis.

METHODS

Aqueous samples from 18 type 2 diabetic patients with DME and 18 type 2 diabetic patients without DME used as controls were analyzed using liquid chromatography-mass spectrometry (LCMS). The two groups of patients were age and gender matched and had no systemic diseases other than diabetes mellitus (DM). The metabolites were analyzed using orthogonal partial least square discriminant analysis.

RESULTS

The metabolite profiles in DME patients differed from those in DM controls. This indicates the following metabolic derangements in DME: (a) a higher amount of oxidized fatty acids but a lower amount of endogenous antioxidants (oxidative stress); (b) higher levels of β-glucose and homocysteine but a lower level of sorbitol (hyperglycemia); (c) a higher amount of prostaglandin metabolites (inflammation); (d) higher amounts of acylcarnitines, odd-numbered fatty acids, and 7,8-diaminononanoate (respiration deterioration); (e) a higher amount of neurotransmitter metabolites and homovanillic acid (neuronal damage); (f) a lower amount of extracellular matrix (ECM) constituents (ECM deterioration); and (g) a higher amount of di-amino peptides (microvascular damage).

CONCLUSIONS

The change in the metabolic profiles in the aqueous humor of DME patients compared to DM controls without DME indicates that DME patients may have less capability to resist various stresses or damaging pathological conditions, such as oxidative stress, mitochondrial insufficiency, inflammation, and ECM deterioration.

Caffeine and Its Neuroprotective Role in Ischemic Events: A Mechanism Dependent on Adenosine Receptors

Ischemia is characterized by a transient, insufficient, or permanent interruption of blood flow to a tissue, which leads to an inadequate glucose and oxygen supply. The nervous tissue is highly active, and it closely depends on glucose and oxygen to satisfy its metabolic demand. Therefore, ischemic conditions promote cell death and lead to a secondary wave of cell damage that progressively spreads to the neighborhood areas, called penumbra. Brain ischemia is one of the main causes of deaths and summed with retinal ischemia comprises one of the principal reasons of disability. Although several studies have been performed to investigate the mechanisms of damage to find protective/preventive interventions, an effective treatment does not exist yet. Adenosine is a well-described neuromodulator in the central nervous system (CNS), and acts through four subtypes of G-protein-coupled receptors. Adenosine receptors, especially A1 and A2A receptors, are the main targets of caffeine in daily consumption doses. Accordingly, caffeine has been greatly studied in the context of CNS pathologies. In fact, adenosine system, as well as caffeine, is involved in neuroprotection effects in different pathological situations. Therefore, the present review focuses on the role of adenosine/caffeine in CNS, brain and retina, ischemic events.

The Narrative Medicine Approach in the Treatment of Diabetic Macular Edema: An Italian Experience

The study retraces the healthcare pathway of patients affected by diabetic macular edema (DME) through the direct voice of patients and caregivers by using a “patient journey” and narrative method approach. The mapping of the patient’s journey was developed by a multidisciplinary board of health professionals and involved four Italian retina centers. DME patients on intravitreal injection therapy and caregivers were interviewed according to the narrative medicine approach. Narratives were analyzed through a quali-quantitative tool, as set by the narrative medicine method. The study involved four specialized retina centers in Italy and collected a total of 106 narratives, 82 from DME patients and 24 from caregivers. The narratives reported their difficulty in identifying the correct pathway of care because of a limited awareness of diabetes and its complications. Patients experienced reduced autonomy due to ocular complications. In the treatment of diabetes and its complications, a multidisciplinary approach currently appears to be missing. DME reduces the quality of life of affected patients. The narrative medicine approach offers qualitative and emotional patient-guided information. The patient journey provides all of those involved in the management of DME with flowcharts to refer to, identifying the critical points in the healthcare journey of DME patients to improve the management of the disease.

Foveal eversion patterns in diabetic macular edema

The aim of the present study was to describe foveal eversion patterns in diabetic macular edema (DME) and to assess their relationship with the course of the disease and the outcome. The study was designed as prospective, observational, with two years of follow-up. DME patients were divided in two groups, one treated by combined anti-VEGF injections and dexamethasone (DEX) implants, and the other treated by fluocinolone acetonide (FAc) implant with additional anti-VEGF retreatments if needed. Main outcome measures were foveal eversion prevalence, foveal eversion patterns, best-corrected visual acuity (BCVA), central macular thickness (CMT), structural OCT metrics, number of intravitreal injections. One hundred and forty-six eyes (146 patients; 80 males; mean age 67 ± 8 years) affected by already treated DME, with 84 eyes treated with anti-VEGF/DEX treatments (mean of 10 ± 3 injections) and 62 treated with FAc implant. Looking at the treatments administered before the inclusion into the study, 84 eyes (58%) were treated with anti-VEGF injections, whereas 62 eyes (42%) underwent a combination of anti-VEGF and corticosteroids implants. DME eyes showed statistically significant improvements of LogMAR BCVA and CMT over the 2-year follow-up. Foveal eversion was found in 83 eyes (57%), categorized as follows: Pattern 1a (16;19%); Pattern 1b (22;27%) and Pattern 2 (45;54%). BCVA improvement was detected in all the subgroups, excepting for Pattern 2, which showed also significantly worse structural OCT parameters. Pattern 1b and Pattern 2 were characterized by significantly higher prevalence of persistent DME (64% and 89% of cases, respectively). Foveal eversion patterns were correlated with progressively worse DME outcome. Foveal eversion may be associated to the loss of foveal homeostasis, with consequent poor response to intravitreal treatments and worse DME outcome.

The Role of Intravitreal Corticosteroids in the Treatment of DME: Predictive OCT Biomarkers

This work aims to summarize predictive biomarkers to guide treatment choice in DME. Intravitreal anti-VEGF is considered the gold standard treatment for centers involving DME, while intravitreal steroid treatment has been established as a second-line treatment in DME. However, more than 1/3 of the patients do not adequately respond to anti-VEGF treatment despite up to 4-weekly injections. Not surprisingly, insufficient response to anti-VEGF therapy has been linked to low-normal VEGF levels in the serum and aqueous humor. These patients may well benefit from an early switch to intravitreal steroid treatment. In these patients, morphological biomarkers visible in OCT may predict treatment response and guide treatment decisions. Namely, the presence of a large amount of retinal and choroidal hyperreflective foci, disruption of the outer retinal layers and other signs of chronicity such as intraretinal cysts extending into the outer retina and a lower choroidal vascular index are all signs suggestive of a favorable treatment response of steroids compared to anti-VEGF. This paper summarizes predictive biomarkers in DME in order to assist individual treatment decisions in DME. These markers will help to identify DME patients who may benefit from primary dexamethasone treatment or an early switch.

Nocturnal normobaric hyperoxia treatment in a case of chronic diabetic macular edema

PURPOSE

To study the long-term anatomic and physiologic effects of nocturnal normobaric hyperoxia (NNBH) in a patient with treatment-resistant diabetic macular edema (DME).

METHODS

A 64-year-old diabetic man with bilateral DME requiring regular anti-VEGF treatments in both eyes was started on 5 LPM (40% FiO2) NNBH treatment 6-h per night. Visual acuity, OCT measurements of retinal thickness and volume, as well as the number of injections given in each eye were retrospectively examined one year prior and prospectively after initiation of NNBH, as well as before and after a planned 1-month discontinuation of NNBH.

RESULTS

The patient received 12 anti-VEGF injections in the year prior to beginning NNBH treatment (4 OD; 8 OS) and did not require any injections after commencing NNBH treatment. Visual acuity improved and stabilized to 20/20 and macular edema rapidly resolved in both eyes following initiation of NNBH. After a planned 1-month NNBH vacation, DME recurred but quickly resolved once NNBH treatment was restarted.

CONCLUSION

This model case demonstrates that a 6-h NNBH regimen can be successful in treating DME and improving vision, without the need for intravitreal injections. NNBH is a more acceptable treatment regimen compared to 24-h continuous oxygen delivery and may provide a less invasive alternate method for treating DME in patients with diabetes. Further study is warranted.

Clinical Comparative Study of Intravitreal Injection of Triamcinolone Acetonide and Aflibercept in the Treatment of Diabetic Retinopathy Cystoid Macular Edema

Objective To compare the curative effect of intravitreal injection of triamcinolone acetonide and aflibercept on diabetic retinopathy (DR) cystoid macular edema. Methods A total of 102 patients with DR cystoid macular edema admitted to the hospital were enrolled between July 2018 and July 2021. According to random number table method, they were divided into the control group (intravitreal injection of triamcinolone acetonide) and the observation group (intravitreal injection of aflibercept), 51 cases in each group. All were followed up for half a year. The clinical curative effect, visual acuity, central subfield macular thickness (CSMT), macular volume, scores of quality of life, and levels of cytokines in aqueous humor (vascular endothelial growth factor (VEGF), monocyte chemoattractant protein-1 (MCP-1), human angiopoietin-like protein 4 (ANGPTL4)] at different time points (before and at 6 months after surgery) were compared between the two groups. The times of drugs injection and occurrence of adverse reactions in both groups were statistically analyzed. Results The total effective rate in observation group was higher than that in the control group (96.08% vs 82.35%) (P < 0.05). After 6 months of treatment, visual acuity was improved, and CSMT and macular volume were decreased in both groups. Also, the above changes were more significant in the observation group than those in the control group (P < 0.05). After 6 months of treatment, levels of cytokines in aqueous humor were decreased in both groups. The levels of VEGF, MCP-1, and ANGPTL4 in observation group were lower than those in the control group (P < 0.05). After 6 months of treatment, quality of life scores in observation group were higher than those in the control group (P < 0.05). In the follow-up period, average times of drugs injection in the observation group were more than those in the control group, and the incidence of adverse reactions was lower than that in control group (5.88% vs 21.57%) (P < 0.05). Conclusion The curative effect of intravitreal injection of both triamcinolone acetonide and aflibercept is good on DR cystoid macular edema. The curative effect of aflibercept is better, which can improve visual acuity and quality of life, and regulate cytokines in aqueous humor, with high safety. However, aflibercept has a high price, and further research is needed to determine whether its price can be matched with clinical benefits. In clinic, medication plan should be selected according to the actual situation.

Change of Optical Coherence Tomography Morphology and Associated Structural Outcome in Diabetic Macular Edema after Ranibizumab Treatment

(1) Background: To investigate the correlation between therapeutic outcome and morphologic changes for diabetic macular edema (DME) after intravitreal injection of ranibizumab (IVIR). (2) Methods: This retrospective study included 228 eyes received IVIR for DME. Each participant was traced for two years after the initial IVIR, while the data of ophthalmic examination, optical coherence tomography (OCT) image, and systemic diseases were collected. The study population was categorized into different subgroups according to the existence of OCT morphologic change and the initial OCT morphologic pattern, including diffuse retinal thickening (DRT), cystoid macular edema (CME), serous retinal detachment (SRD), and vitreomacular interface abnormalities (VMIAs). The primary outcomes were the baseline best-corrected visual acuity (BCVA) and central macular thickness (CMT) during a two-year study period. The distribution of OCT morphologic change and its relation to primary outcome were analyzed. (3) Results: Comparing the 42 eyes (18.4%) with OCT morphological changes to another 186 eyes (81.6%) without such alteration, the former showed a poorer baseline BCVA (0.84 ± 0.39 vs. 0.71 ± 0.36, p = 0.035), worse final BCVA (0.99 ± 0.44 vs. 0.67 ± 0.30, p = 0.001), and thicker final CMT (354.21 ± 89.02 vs. 305.33 ± 83.05, p = 0.001). Moreover, the VMIA developed in 14.9% of all DME patients presenting the most common morphologic change among DRT, CME, and SRD. Besides, the presence of stroke was independently correlated to the morphologic change (adjusted odds ratio [aOR]: 6.381, 95% confidence interval (CI): 1.112–36.623, p = 0.038). (4) Conclusions: The change of OCT morphology in DME patients receiving IVIR was correlated to worse structural and visual outcome while the formation of VMIA most commonly occurred after initial treatment.

Administration of Melatonin in Diabetic Retinopathy Is Effective and Improves the Efficacy of Mesenchymal Stem Cell Treatment

Stem cell transplantation is a promising therapeutic technique for the treatment of a variety of diseases; nevertheless, stem cell therapy may not always work as well as it could. The goal of this study was to test the hypothesis that employing a powerful antioxidant like melatonin improves stem cell transplantation success and potentiates stem cell function in the therapy of diabetic retinopathy. For this purpose, 50 adult male rats were divided into the following: control group: this group received 0.5 ml of 0.1 M of sodium citrate buffer (pH = 4.5) (intraperitoneal (I.P.)). The confirmed diabetic rats were divided into 4 groups: diabetic group: confirmed diabetic rats received no treatments with a regular follow of the blood glucose profile for 8 weeks; melatonin group: confirmed diabetic rats received melatonin (5 mg/kg/day); stem cell group: the confirmed diabetic rats were given intravitreal injection of stem cells (2 μl cell suspension of stem cells (3 × 10⁴ cells/μl)); and melatonin+stem cell group: confirmed diabetic rats received melatonin (5 mg/kg/day), orally once daily for 8 weeks, and 2 μl cell suspension of stem cells (3 × 10⁴ cells/μl) was carefully injected into the vitreous cavity. Our results showed that administration of melatonin and/or stem cell restored the retinal oxidative/antioxidant redox and reduced retinal inflammatory mediators. Coadministration of melatonin and stem cells enhanced the number of transplanted stem cells in the retinal tissue and significantly reduced retinal BDEF, VEGF, APOA1, and RBP4 levels as compared to melatonin and/or stem alone. We may conclude that rats treated with melatonin and stem cells had their retinal oxidative/antioxidant redox values restored to normal and their histological abnormalities reduced. These findings support the hypothesis that interactions with the BDEF, VEGF, APOA1, and RBP4 signaling pathways are responsible for these effects.

Identifying Genetic Biomarkers Predicting Response to Anti-Vascular Endothelial Growth Factor Injections in Diabetic Macular Edema

Intraocular anti-vascular endothelial growth factor (VEGF) therapies are the front-line treatment for diabetic macular edema (DME); however, treatment response varies widely. This study aimed to identify genetic determinants associated with anti-VEGF treatment response in DME. We performed a genome-wide association study on 220 Australian patients with DME treated with anti-VEGF therapy, genotyped on the Illumina Global Screening Array, and imputed to the Haplotype Reference Consortium panel. The primary outcome measures were changes in central macular thickness (CMT in microns) and best-corrected visual acuity (BCVA in ETDRS letters) after 12 months. Association between single nucleotide polymorphism (SNP) genotypes and DME outcomes were evaluated by linear regression, adjusting for the first three principal components, age, baseline CMT/BCVA, duration of diabetic retinopathy, and HbA1c. Two loci reached genome-wide significance (p < 5 × 10−8) for association with increased CMT: a single SNP on chromosome 6 near CASC15 (rs78466540, p = 1.16 × 10−9) and a locus on chromosome 12 near RP11-116D17.1 (top SNP rs11614480, p = 2.69 × 10−8). Four loci were significantly associated with reduction in BCVA: two loci on chromosome 11, downstream of NTM (top SNP rs148980760, p = 5.30 × 10−9) and intronic in RP11-744N12.3 (top SNP rs57801753, p = 1.71 × 10−8); one near PGAM1P1 on chromosome 5 (rs187876551, p = 1.52 × 10−8); and one near TBC1D32 on chromosome 6 (rs118074968, p = 4.94 × 10−8). In silico investigations of each locus identified multiple expression quantitative trait loci and potentially relevant candidate genes warranting further analysis. Thus, we identified multiple genetic loci predicting treatment outcomes for anti-VEGF therapies in DME. This work may potentially lead to managing DME using personalized treatment approaches.

Association of metformin treatment with enhanced effect of anti-VEGF agents in diabetic macular edema patients

PURPOSE

To investigate the effect of metformin combined with anti-VEGF agents in patients with diabetic macular edema (DME).

METHODS

This study was a prospective, nonrandomized case-control study. Patients were included in with a diagnosis of DME who received anti-VEGF agents injection. Basic information, medical history, best-corrected visual acuity (BCVA), central macular thickness (CMT), the number of intravitreal injections, panretinal photocoagulation (PRP), and macular grid photocoagulation treatment during the 6-month follow-up, were recorded for each patient.

RESULTS

A total of 50 DME patients were collected (24 patients with a history of oral metformin ≥ 6 months and 26 patients who had not taken metformin). The BCVA and the CMT were significantly improved after anti-VEGF treatment in two groups (F1 = 19.35, F2 = 26.78; F1 = 65.45, F2 = 76.23; P < 0.05). The BCVA in the metformin group was better than that in non-metformin group at every point after treatment (F = 34.45, P < 0.05). The CMT in metformin group decreased much more than that in non-metformin group during the follow-up period (F = 87.05, P < 0.05). The injection numbers decreased in the metformin group compared with the non-metformin group (t = 5.14, P < 0.05). However, there was no difference in PRP and macular grid photocoagulation therapy between the two groups during the 6-month follow-up.

CONCLUSION

Metformin can enhance the therapeutic effect of anti-VEGF agents on DME patients to improve their visual acuity, improve the structure of the macular area, and reduce the number of intravitreal injections 90.