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

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.

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.

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.

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.

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.

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.

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.

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.

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 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.

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.

The Optimization of an Anti-VEGF Therapeutic Regimen for Neovascular Glaucoma

This study investigates the safety and efficacy of conbercept injection through different routes for neovascular glaucoma (NVG) treatment, in which seventy-four patients (81 eyes) with NVG caused by ischemia retinopathy had participated. Patients were divided into three stages according to the progression of NVG and were randomly assigned to receive intracameral or intravitreal conbercept injection. After conbercept injection, patients experienced improved best-corrected visual acuity (BCVA), good intraocular pressure (IOP) control, and neovascularization of Iris (NVI) regression. In stage III, patients required trabeculectomy with mitomycin C plus pan-retinal photocoagulation (PRP) to achieve complete NVI regression. Compared to the intravitreal group, the intracameral group had significantly lower IOP in 2 days in stage III and 1 day in stages I and II after injection, complete NVI regression before PRP in stages I and II, and better NVI regression in stage III. The rates of hyphema after trabeculectomy and malfunction filtering bleb suffering needle bleb revision were lower in the intracameral group, but only the hyphema rate was significantly different. Injections through different routes are all safe. We recommend intravitreal injections for patients in stages I and II, but for stage III, intracameral injection is better, and trabeculectomy with mitomycin C should be conducted within 2 days after injection to maximally reduce the risk of perioperative hyphema.

Trial Registration:ClinicalTrials.gov, identifier NCT03154892.

Vitreous microparticles contain apoptotic signals suggesting a diabetic vitreopathy

AIM

To evaluate differences in microparticle profiles in vitreous samples between diabetic and non-diabetic eyes undergoing vitrectomy.

METHODS

Un-masked cross-sectional series of 34 eyes undergoing vitrectomy. Vitreous specimens were collected and processed to evaluate for membrane integrity (DAPI), apoptosis (Annexin-V), and endothelial-cell origin (V-Cadherin). A BD LSR II flow cytometer was used for analysis and standardized sub-micron-sized beads were used for size comparison.

RESULTS

Thirty-four specimens underwent analysis. Greater levels of Annexin-V were found on microparticles from specimens in which blood had entered the vitreous (n=12) compared to those without blood (n=22; 52.3%±30.7% vs 19.6%±27.2%, P=0.002). Patients with diabetes having surgery with hemorrhage (n=7) had greater expression of Annexin-V than those without hemorrhage (n=8; 62.1%±31.7% vs 18.9%±20.9%, P=0.009). However, in patients with non-diabetic vitreous hemorrhage, the level of Annexin-V expression was not significantly different compared to other disease processes (38.6%±25.7%, n=5 vs 20.0%±30.9%, n=14, P=0.087).

CONCLUSION

Increased expression of the apoptotic marker, Annexin-V is detected on vitreous microparticles in diabetes-related vitreous hemorrhage. When evaluating vitreous hemorrhage in patients without diabetes, the apoptotic signal is not significantly different. Vitrectomy in patients with diabetes, and improvement in visual outcomes, may be related to the removal of a serum-derived, pro-apoptotic vitreous. Further investigation is warranted in order to identify the molecular characteristics of microparticles that regulate disease.

Associations Between Diabetic Retinal Microvasculopathy and Neuronal Degeneration Assessed by Swept-Source OCT and OCT Angiography

Purpose: To provide clinical evidence of the associations between retinal neuronal degeneration and microvasculopathy in diabetic retinopathy (DR). Methods: This case-control study included 76 patients (76 eyes) with type 2 diabetes mellitus (DM), and refraction error between -3.0 and +3.0 D. The eyes were assigned into DM (without DR), non-proliferative DR (NPDR), and proliferative DR (PDR) groups. Age-, sex-, and refractive error-matched normal subjects were enrolled as controls. The mean retinal thickness (mRT), the relative mean thickness of the retinal nerve fiber layer (rmtRNFL, mtRNFL/mRT), ganglion cell layer (rmtGCL), ganglion cell complex (rmtGCC) layer, foveal avascular zone area (FAZa), FAZ perimeter (FAZp), FAZ circularity index (FAZ-CI), and vessel density (VD) in superficial capillary plexus (SCP) and deep capillary plexus (DCP) were assessed by swept-source optical coherence tomography (OCT) and OCT angiography (OCTA). Group comparison and Spearman's partial correlation coefficient analysis were applied to evaluate the correlation between these morphological parameters. Results: rmtRNFL, FAZa, and FAZp in SCP and DCP increased with the DR severity (p _rmtRNFL < 0.001; p _{FAZa, SCP} = 0.001; p _FAZa , _DCP = 0.005; p _FAZp , _SCP < 0.001; p _FAZp , _DCP < 0.001). The rmtGCL, FAZ-CI in SCP and DCP, and VD in DCP decreased with the DR severity (p _rmtGCL = 0.002, p _FAZ-CI , _SCP = 0.002; p _{FAZ-CI, DCP} < 0.001, p _VD , _DCP < 0.001). After controlling age, sex, duration of diabetes, and hypertension, the rmtRNFL, FAZa in SCP and DCP, and FAZp in SCP and DCP were correlated with the severity of DR (p < 0.05), while VD in SCP and DCP, FAZ-CI, and rmtGCL were negatively correlated with the severity of DR (p < 0.05). The rmtGCL was negatively correlated with the FAZa in SCP (r = -0.34, p = 0.002) and DCP (r = -0.23, p = 0.033), and FAZp in SCP (r = -0.37, p = 0.001) and DCP (r = -0.32, p = 0.003), but positively correlated with VD in SCP (r = 0.26, p = 0.016), VD in DCP (r = 0.28, p = 0.012), and FAZ-CI in DCP (r = 0.31, p = 0.006). Conclusions: rmtRNFL, FAZ-CI in SCP and DCP, and FAZp in SCP are strong predictors of the severity of DR. The ganglion cell body loss is highly correlated with increased FAZp and FAZa, decreased FAZ-CI, and reduced VD with the severity of DR.

Intravitreal Tissue Plasminogen Activator Injection for Treatment-Resistant Diabetic Macular Edema of the Vitrectomized Eye

Diabetic macular edema (DME) is the main cause of visual loss in patients with diabetic retinopathy. DME has been treated using intravitreal anti-vascular endothelial growth factor (VEGF) drugs, steroids, laser photocoagulation, vitreoretinal surgery, and their combinations. These modalities are generally effective in preserving vision, but they sometimes produce only limited responses in patients with persistent or refractory DME. The levels of various inflammatory factors, including cytokines, chemokines, and extracellular matrices, as well as VEGF in the vitreous fluid, are increased in patients with DME. Excessive fibrinogen/fibrin levels in the vitreous fluid or fibrin deposition in the retina also contribute to DME pathogenesis. Tissue plasminogen activator (t-PA) promotes the degradation of fibrinogen or fibrin. Intravitreal t-PA injection is a commonly used treatment for subretinal hemorrhage secondary to age-related macular degeneration. Intravitreal t-PA injections have previously been used to restore vision by inducing posterior vitreous detachment in patients with DME. Herein, we describe the visual outcomes of intravitreal t-PA injection in a 78-year-old woman with treatment-resistant DME in her vitrectomized eye after several previous treatments. Before the injection, her best-corrected visual acuity (BCVA) was 0.7 logMAR and central foveal retinal thickness (CRT) was 735 μm. At 1 month after the injection, her BCVA was 0.8 logMAR and CRT was 558 μm, and 3 months later, her BCVA was 0.8 logMAR and CRT was 207 μm. Her BCVA was sustained, and CRT showed gradual improvements. These findings suggested the effectiveness of intravitreal t-PA injections for DME in the vitrectomized eye.

Histopathological assessments reveal retinal vascular changes, inflammation, and gliosis in patients with lethal COVID-19

Purpose

The purpose of this study is to assess for histopathological changes within the retina and the choroid and determine the long-term sequelae of the SARS-CoV-2 infection.

Methods

Eyes from seven COVID-19-positive and six similar age-matched control donors with a negative test for SARS-CoV-2 were assessed. Globes were evaluated ex vivo with macroscopic, SLO and OCT imaging. Macula and peripheral regions were processed for Epon embedding and immunocytochemistry.

Results

Fundus analysis shows hemorrhagic spots and increased vitreous debris in several of the COVID-19 eyes compared to the controls. OCT-based measurements indicated an increased trend in retinal thickness in the COVID-19 eyes; however, the difference was not statistically significant. Histology of the retina showed presence of hemorrhages and central cystoid degeneration in several of the donors. Whole mount analysis of the retina labeled with markers showed changes in retinal microvasculature, increased inflammation, and gliosis in the COVID-19 eyes compared to the controls. The choroidal vasculature displayed localized changes in density and signs of increased inflammation in the COVID-19 samples.

Conclusions

In situ analysis of the retinal tissue suggests that there are severe subclinical abnormalities that could be detected in the COVID-19 eyes. This study provides a rationale for evaluating the ocular physiology of patients that have recovered from COVID-19 infections to further understand the long-term effects caused by this virus.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-021-05460-1.

The Effect of Ranibizumab Loading Treatment on Vision-Related Quality of Life in Diabetic Macular Edema

AIMS

To investigate the changes in vision-related quality of life after a loading dose of three consecutive intravitreal ranibizumab (IVR) injections in patients with unilateral diabetic macular edema (DME).

MATERIALS AND METHODS

Fifty-two eyes of 52 patients who received IVR injections in only one eye with DME were included in our study. The following characteristics of the patients were recorded: gender, education status, marital status, work status, presence of chronic disease. The changes in best-corrected visual acuity (BCVA) and central macular thickness (CMT) were evaluated at baseline (before treatment) and 1 month after the third intravitreal injection (after treatment). Patients were administered the Turkish form of the National Eye Institute 25-Item Visual Functions Questionnaire (NEI VFQ-25 TR). The quality of life scores assessed by the NEI VFQ-25 TR, the BCVA, intraocular pressure (IOP), and CMT measurements were compared at baseline (before treatment) and 1 month after the third intravitreal injection (after treatment).

RESULTS

We enrolled 52 patients (25 females, 27 males) in our study; mean age was 64.35 ± 9.26 years. After treatment, BCVA improved significantly (p = 0.001), and macular thickness decreased significantly (p < 0.001). All NEI VFQ-25 TR subscale scores were significantly higher after treatment (p < 0.05). However, no significant correlation was found between the change in BCVA and CMT and the change in NEI VFQ-25 TR subscale and composite scores. The increase in near activities scores was significantly higher in males (p = 0.020) and in the retired group (p = 0.022). There were no significant differences in the changes in NEI VFQ-25 TR subscale and composite scores in relation to educational status.

DISCUSSION

Significant improvements in BCVA, macular edema, and vision-related quality of life were found in DME patients who received IVR injections with a loading dose, as shown by the NEI VFQ-25 TR. Interestingly, a significant improvement in quality of life was observed even though the patients could see well with the fellow eye. In conclusion, the NEI VFQ-25 TR is a useful scale to evaluate the changes in visual function and psychosocial characteristics of DME patients after treatment.

Recent Advancements in the Medical Treatment of Diabetic Retinal Disease

Diabetic retinal disease remains one of the most common complications of diabetes mellitus (DM) and a leading cause of preventable blindness. The mainstay of management involves glycemic control, intravitreal, and laser therapy. However, intravitreal therapy commonly requires frequent hospital visits and some patients fail to achieve a significant improvement in vision. Novel and long-acting therapies targeting a range of pathways are warranted, while evidence to support optimal combinations of treatments is currently insufficient. Improved understanding of the molecular pathways involved in pathogenesis is driving the development of therapeutic agents not only targeting visible microvascular disease and metabolic derangements, but also inflammation and accelerated retinal neurodegeneration. This review summarizes the current and emerging treatments of diabetic retinal diseases and provides an insight into the future of managing this important condition.

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.

ERM Complex, a Therapeutic Target for Vascular Leakage Induced by Diabetes

BACKGROUND

Ezrin, radixin, and moesin (the ERM complex) interact directly with membrane proteins regulating their attachment to actin filaments. ERM protein activation modifies cytoskeleton organization and alters the endothelial barrier function, thus favoring vascular leakage. However, little is known regarding the role of ERM proteins in diabetic retinopathy (DR).

OBJECTIVE

This study aimed to examine whether overexpression of the ERM complex exists in db/db mice and its main regulating factors.

METHOD

9 male db/db mice and 9 male db/+ aged 14 weeks were analyzed. ERM proteins were assessed by western blot and by immunohistochemistry. Vascular leakage was determined by the Evans blue method. To assess ERM regulation, HRECs were cultured in a medium containing 5.5 mM D-glucose (mimicking physiological conditions) and 25 mM D-glucose (mimicking hyperglycemia that occurs in diabetic patients). Moreover, treatment with TNF-α, IL-1β, or VEGF was added to a high glucose condition. The expression of ERM proteins was quantified by RT-PCR. Cell permeability was evaluated by measuring movements of FITC-dextran.

RESULTS

A significant increase of ERM in diabetic mice in comparison with non-diabetic mice was observed. A high glucose condition alone did not have any effect on ERM expression. However, TNF-α and IL-1β induced a significant increase in ERM proteins.

CONCLUSIONS

The increase of ERM proteins induced by diabetes could be one of the mechanisms involved in vascular leakage and could be considered as a therapeutic target. Moreover, the upregulation of the ERM complex by diabetes is induced by inflammatory mediators rather than by high glucose itself.

Melatonin prevents blood-retinal barrier breakdown and mitochondrial dysfunction in high glucose and hypoxia-induced in vitro diabetic macular edema model

Diabetic macular edema (DME) is a leading cause of blindness in diabetic retinopathy. Prolonged hyperglycemia plus hypoxia contributes to DME pathogenesis. Retinal pigmented epithelial cells comprise the outer blood-retinal barrier and are essential for maintaining physiological functioning of the retina. Melatonin acts as an antioxidant and regulator of mitochondrial bioenergetics and has a protective effect against ocular diseases. However, the role of mitochondrial dysfunction and the therapeutic potential of melatonin in DME remain largely unexplored. Here, we used an in vitro model of DME to investigate blood-retinal barrier integrity and permeability, angiogenesis, mitochondrial dynamics, and apoptosis signaling to evaluate the potential protective efficacy of melatonin in DME. We found that melatonin prevents cell hyper-permeability and outer barrier breakdown by reducing HIF-1α, HIF-1β and VEGF and VEGF receptor gene expression. In addition, melatonin reduced the expression of genes involved in mitochondrial fission (DRP1, hFis1, MIEF2, MFF), mitophagy (PINK, BNip3, NIX), and increased the expression of genes involved in mitochondrial biogenesis (PGC-1α, NRF2, PPAR-γ) to maintain mitochondrial homeostasis. Moreover, melatonin prevented apoptosis of retinal pigmented epithelial cells. Our results suggest that mitochondrial dysfunction may be involved in DME pathology, and melatonin may have therapeutic value in DME, by targeting signaling in mitochondria.

DIABETIC MACULAR EDEMA AND CATARACT SURGERY: Phacoemulsification Combined With Dexamethasone Intravitreal Implant Compared With Standard Phacoemulsification

PURPOSE

To compare functional and anatomical results of combined phacoemulsification and dexamethasone intravitreal implant (Ozurdex; DEX-I) with standard phacoemulsification in diabetic patients with cataract.

METHODS

Retrospective, comparative, cohort study. Patients with nonproliferative diabetic retinopathy, macular edema, and cataract, treated routinely at the Eye Clinic, Azienda Ospedaliero Universitaria Policlinico, Bari, Italy with phacoemulsification associated with DEX-I (n = 23; Phaco-Dex) or standard phacoemulsification (n = 23; Phaco-alone). Best-correct visual acuity, central subfield thickness, and intraocular pressure were assessed at baseline and monthly for 3 months after surgery, and t-test was used to assess change from baseline. A multilevel regression model with an unstructured correlation-type matrix to account for repeated data measures was used for statistical analysis in and between groups.

RESULTS

With Phaco-Dex, best-correct visual acuity increased significantly from the first month (P = 0.0005 vs. baseline) and remained stable at the following visits; central subfield thickness decreased significantly from Month 2 (P = 0.049 and P = 0.04 vs. baseline, respectively); at each timepoint, central subfield thickness was significantly lower in the Phaco-Dex group versus Phaco-alone. Intraocular pressure increased significantly during follow-up (P = 0.001 at Month 3 vs. baseline) but remained within the normal range. In the Phaco-alone group, best-correct visual acuity, and intraocular pressure did not show any significant changes after surgery, whereas central subfield thickness increased from Month 2 (P = 0.05 vs. baseline).

CONCLUSION

In diabetic patients with macular edema and visually significant cataract, combined treatment with phacoemulsification and DEX-I seemed to be effective, safe, and superior to standard phacoemulsification considering both functional and tomographic parameters.

Outcome of Single Dexamethasone Implant Injection in the Treatment of Persistent Diabetic Macular Edema After Anti-VEGF Treatment: Real-Life Data from a Tertiary Hospital in Jordan

Purpose

To analyze the real-life clinical outcome of a single dexamethasone implant (DEX) injection in the treatment of persistent diabetic macular edema (DME) after anti-vascular endothelial growth factor (anti-VEGF) agents in a sample of the Jordanian population.

Methods

An observational case study design that involved a retrospective chart review analysis in a tertiary hospital in Amman, Jordan. Patients who showed persistent DME after receiving at least six doses of anti-VEGF agents for DME treatment were included.

Results

The study population consisted of 72 participants (29 females, 43 males) having an average age of 66 years. All patients had best-corrected visual acuity (BCVA) less than 0.7 (6/9) and SD-OCT documented center-involved DME. The study results showed that the average baseline BCVA improved from 0.205±0.1 before DEX injection to 0.358±0.1 at 3 months post-injection (p<0.0001). The central mean thickness (CMT) showed significant improvement also (539.347±132.402 to 379.041±99.430, p<0.0001). There was a mean of 3 mmHg increase in intraocular pressure at 3 months post-injection (p<0.0001), however, only 4% of patients required medical treatment. Other inflammatory biomarkers in OCT, such as intraretinal hyper-reflective dots (HRD), showed significant improvement also (23.67±16 to 14.83±13, p<0.0001). No other significant safety concerns were noticed.

Conclusion

A single DEX injection showed significant clinical and anatomical improvement in DME cases that are persistent after anti-VEGF treatment in our sample, with an excellent safety profile. In case of supply shortage of intravitreal injections, which occurs frequently at our center, a single DEX injection may be utilized as an effective DME therapy. Further research is mandated to identify clinical response in a larger sample and more frequent injections.

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 A_2A 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.

Comparison of Subthreshold 532 nm Diode Micropulse Laser with Conventional Laser Photocoagulation in the Treatment of Non-Centre Involved Clinically Significant Diabetic Macular Edema

BACKGROUND

The aim of the study was to investigate the effect of the 532 nm (green) diode subthreshold micropulse laser (SML) in the treatment of non-centre involved clinically significant macular edema (CSME) in comparison to the conventional laser photocoagulation (CLP).

METHODS

A total of 60 eyes of patients diagnosed with non-centre involved CSME were randomly divided into two groups. SML photocoagulation was performed in the first group (G1), while CLP in the second one (G2). Central macular thickness (CMT) and best corrected visual acuity (BCVA) were measured prior to treatment and at 3 and 6 months after intervention.

RESULTS

G1 participants had significantly better CMT at 6 months after laser application (p = 0.04) compared to G2. Additionally, CMT in both groups was significantly lower 6 months after laser application in comparison to baseline values (G1: p < 0.001, G2: p = 0.002). Moreover, significant improvement was detected 6 months after SML in G1 regarding BCVA compared to values before laser treatment (p = 0.001).

CONCLUSION

SML was more effective than CLP in reducing CMT and improving BCVA in patients with non-centre involved CSME. Therefore, it seems that SML can be a good substitute for CLP in DME treatment if confirmed in future studies.