Increased levels of vascular endothelial growth factor and interleukin-6 in the aqueous humor of diabetics with macular edema

Hyperreflective Retinal Foci (HRF): Definition and Role of an Invaluable OCT Sign

Background: Hyperreflective retinal foci (HRF) are small, discrete, hyperreflective elements observed in the retina using optical coherence tomography (OCT). They appear in many retinal diseases and have been linked to disease progression, treatment response, and prognosis. However, their definition and clinical use vary widely, not just between different diseases, but also within a single disorder. Methods: This perspective is based on a review of peer-reviewed studies examining HRF across different retinal diseases. The studies included analyzed HRF morphology, distribution, and clinical relevance using OCT. Particular attention was given to histopathological correlations, disease-specific patterns, and advancements in automated quantification methods. Results: HRF distribution and features vary with disease type and even within the same disease. A variety of descriptions have been proposed with different characteristics in terms of dimensions, reflectivity, location, and association with back shadowing. Automated OCT analysis has enhanced HRF detection, enabling quantitative analysis that may expand their use in clinical practice. However, differences in software and methods can lead to inconsistent results between studies. HRF have been linked to microglial cells and may be defined as neuro-inflammatory cells (Inflammatory, I-HRF), migrating retinal pigment epithelium cells (Pigmentary, P-HRF), blood vessels (Vascular, V-HRF), and deposits of proteinaceous or lipid elements leaking from vessels (Exudative, E-HRF). Conclusions: HRF are emerging as valuable imaging biomarkers in retinal diseases. Four main types have been identified, with different morphological features, pathophysiological origin, and, therefore, different implications in the management of retinal diseases. Advances in imaging and computational analysis are promising for their incorporation into personalized treatment strategies.

Impact of diabetes and diabetic retinopathy on neovascular exudative age-related macular degeneration

BACKGROUND

To evaluate the functional and morphological changes in patients with nAMD undergoing anti-VEGF therapy, focusing on the impact of concomitant diabetes with or without diabetic retinopathy.

METHODS

This retrospective cohort study included 1096 eyes from 916 patients with nAMD treated at the retina department of the University of Bari between August 2017 and May 2023. Patients were divided into two groups: 892 eyes without diabetes and 204 eyes with diabetes. Best-corrected visual acuity (BCVA), central retinal thickness (CRT) and presence of intraretinal fluid (IRF), subretinal fluid (SRF), subretinal hyperreflective material (SHRM) and atrophy were assessed at baseline, post-loading phase and at 12-month follow-up.

RESULTS

At baseline, no significant differences were observed between groups. Post-loading phase, both groups showed significant improvements in BCVA and reductions in CRT. However, SRF persistence was notably more frequent in the diabetic group (64.2% vs. 27.2%, p < 0.001). At 12 months, SRF was present in 53.7% of the diabetic group compared to 34.9% of the non-diabetic group (p < 0.001). Diabetic patients with moderate diabetic retinopathy (DR) exhibited significantly higher SRF persistence compared to those with mild DR or no DR.

CONCLUSIONS

While anti-VEGF therapy improves visual and anatomical outcomes in both diabetic and non-diabetic patients with nAMD, diabetic patients, particularly those with more severe DR, experience a higher rate of persistence of SRF. This suggests a less than optimal anatomic treatment response and the potential need for more tailored management strategies in this patient population.

PRECIS

This retrospective cohort study investigated the impact of diabetes mellitus and diabetic retinopathy on neovascular age-related macular degeneration treatment outcomes. The study analysed 1096 eyes from 916 patients undergoing anti-VEGF therapy over 12 months.

HDAC6 mediates NLRP3 inflammasome activation in the pathogenesis of diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR), a major blindness cause in developed countries, is intricately linked to diabetes management and its duration. Here, we demonstrate that HDAC6 mediates NLRP3 inflammasome activation under diabetic conditions, leading to retinal inflammation and degeneration.

METHODS

This study demonstrated the therapeutic effects of HDAC6 genetic ablation, pharmacological inhibition, and HDAC6-deficient bone marrow transplantation in a diabetes model induced by streptozotocin and a high-fat diet. The therapeutic potential was evaluated from a metabolic perspective, including ocular pathologies such as retinal lesions, neovascularization, and vascular leakage.

RESULTS

We discovered that inhibition or genetic ablation of HDAC6 markedly alleviates DR symptoms by dampening NLRP3 inflammasome activation and mitigating retinal damage. Moreover, bone marrow transplantation from HDAC6-deficient mice into wild-type counterparts reversed DR symptoms, underscoring the significance of HDAC6 in systemic immune regulation. The study introduces a novel HDAC6 inhibitor, noted for superior bioavailability and blood-retinal barrier permeability, further highlights the therapeutic promise of targeting HDAC6 in DR.

CONCLUSIONS

Our findings not only underscore the crucial role of HDAC6 in the immune regulatory mechanisms underlying DR pathogenesis through NLRP3 inflammasome activation but also position HDAC6 inhibition as a promising strategy for addressing diabetic complications beyond DR.

Dexamethasone Implant under a Proactive Treatment Regimen in a Clinical Setting: The ProDEX Study

PURPOSE

To assess the effectiveness of switching intravitreal dexamethasone implants (DEX-implant) from pro re nata (PRN) treatment regimen to a proactive regimen in patients with macular edema of diverse etiologies.

DESIGN

An observational, retrospective, uncontrolled, multicenter, national case series.

PARTICIPANTS

Eighty-one eyes from 68 patients treated between October 2015 and June 2023 were included.

METHODS

This study included consecutive eyes treated with DEX-implant who were switched from a PRN regimen to a proactive regimen for diabetic macular edema (DME), retinal vein occlusion (RVO), noninfectious uveitis macular edema (UME; including postsurgical macular edema), and radiation maculopathy (RM).

MAIN OUTCOME MEASURES

The main outcome measures were change in the best-corrected visual acuity (BCVA), central macular thickness (CMT), and intraocular pressure (IOP) at each visit.

RESULTS

According to the etiology, DME represented 49.4% of eyes, UME 24.3%, RVO 21.0%, and RM 6.2%. The mean (standard deviation [SD]) duration of follow-up under the PRN and proactive regimens was 20.6 (13.3) and 14.2 (10.3) months, respectively. Switching from a PRN to a proactive regimen significantly improved mean (SD) BCVA by 3.7 (12.9) ETDRS letters (P = 0.01) with a mean (SD) decrease in CMT of 108.0 (151.4) μm (P < 0.001). The proportion of visits with significant anatomic recurrence (> 50 μm) also decreased from 40.1% to 6.0% after switching to a proactive regimen (P < 0.001). The number of DEX-implant injections significantly increased during the proactive treatment period (P < 0.001), but the change in the number of visits was not significantly different (P = 0.2). The proactive treatment period was not associated with a significant increase in IOP (P = 0.6).

CONCLUSIONS

Switching to a proactive regimen in patients already treated with DEX-implant seems to significantly improve BCVA and CMT while maintaining stable IOP.

FINANCIAL DISCLOSURES

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

Aqueous humour interleukin-6 and vision outcomes with anti-vascular endothelial growth factor therapy

BACKGROUND

This analysis evaluated aqueous humour (AH) interleukin (IL)-6 concentrations and the association between AH IL-6 and visual outcomes in patients with neovascular age-related macular degeneration (nAMD) or diabetic macular oedema (DMO) receiving anti-vascular endothelial growth factor (VEGF) monotherapy.

METHODS

Post hoc analysis of the multicentre, double-masked, randomised HARBOR (NCT00891735) and READ-3 (NCT01077401) trials. HARBOR enrolled treatment-naïve nAMD patients. READ-3 enrolled treatment-naïve/previously treated DMO patients. HARBOR patients received ranibizumab 0.5 or 2.0 mg monthly or as needed; AH samples were collected at month 2, after two previous intravitreal injections. READ-3 patients received ranibizumab 0.5 or 2.0 mg as needed; AH samples were collected at baseline and months 3, 6, 9, and 12.

MAIN OUTCOME MEASURE

association between AH IL-6 concentrations and month 24 best-corrected visual acuity (BCVA).

RESULTS

In both trials (HARBOR, N = 36; READ-3, N = 137), patients with higher AH IL-6 concentrations had worse visual outcomes. HARBOR patients with low AH IL-6 concentrations at month 2 had a mean (95% CI) BCVA change at month 24 of +2.9 (-2.6, 8.3) letters, whereas patients with high AH concentrations had a mean (95% CI) BCVA change of -9.0 (-22.7, 4.7) letters. READ-3 patients with low AH concentrations at baseline had a mean (95% CI) BCVA change at month 12 of +9.3 (7.4, 11.3) letters, whereas patients with high AH concentrations had a mean (95% CI) BCVA change of +5.6 (2.2, 9.1) letters.

CONCLUSIONS

Higher IL-6 AH concentrations may predict suboptimal visual responses to anti-VEGF monotherapy in patients with nAMD/DMO.

Effects of a fortified balanced salt solution and Ringer's lactate solution on anterior chamber inflammation after phacoemulsification in diabetes

PURPOSE

To compare the effects of a fortified balanced salt solution (fSS) and Ringer's lactate solution (Ringer) on anterior chamber (AC) inflammation in patients undergoing phacoemulsification.

SETTING

Tianjin Medical University Eye Hospital, Tianjin, China.

DESIGN

Prospective masked controlled trial.

METHODS

80 patients (40 patients with regular cataract and 40 cataract patients with diabetes mellitus [DM]) were randomized to receive either fSS (n = 40) or Ringer's solution (n = 40). Anterior-segment optical coherence tomography was used to evaluate AC cells and flare. Transepithelial electrical resistance (TEER) and zonula occludens-1 (ZO-1) immunofluorescence were used for tight junction examination. Monocytic leukemia cell line (Tohoku Hospital Pediatrics-1 [THP-1]) transmigration assay was performed to observe the effects of the 2 perfusates on the inflammatory response in vitro.

RESULTS

In patients with regular cataracts, postoperative AC cells and flare on the 1st and 7th days were not significantly different between the Ringer and fSS groups. However, in cataract patients with DM, AC cells were higher in the Ringer group than in the fSS group ( P = .003) on postoperative day 1. The AC flare was also significantly higher in the Ringer group than in the fSS group ( P < .0001). No significant differences between the groups were observed on day 7. Compared with Ringer, fSS increased the TEER value and ZO-1 content and reduced the adhesion of THP-1 cells.

CONCLUSIONS

The results of this study indicated that early postoperative AC inflammation is more severe in patients with cataracts and DM. In addition, fSS attenuates inflammation by protecting the blood-aqueous barrier and inhibiting the exudation of inflammatory cells.

The role of retinal glial cells and related factors in macular edema

Macular edema (ME) has emerged as a leading cause of visual impairment, representing a critical clinical manifestation and complication associated with many eye diseases. In the occurrence and development of ME, retinal glial cells like Müller cells and microglial cells play vital roles. Moreover, growth factor and cytokines associated with them, such as vascular endothelial growth factor (VEGF), pigment epithelium-derived factor (PEDF), hypoxia-inducible factor-1α (HIF-1α), angiopoietin-like protein 4 (ANGPTL4), interleukin-6(IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), prostaglandin, etc., also take part in the pathogenesis of ME. Changes in these cytokines can lead to retinal angiogenesis, increased vascular permeability, blood-retinal barrier (BRB) breakdown, and fluid leakage, further causing ME to occur or deteriorate. Research on the role of retinal glial cells and related cytokines in ME will provide new therapeutic directions and effective remedies. This article is a literature review on the role of Müller cells, microglial cells and related factors in ME pathogenesis.

Glial cell alterations in diabetes-induced neurodegeneration

Type 2 diabetes mellitus is a global epidemic that due to its increasing prevalence worldwide will likely become the most common debilitating health condition. Even if diabetes is primarily a metabolic disorder, it is now well established that key aspects of the pathogenesis of diabetes are associated with nervous system alterations, including deleterious chronic inflammation of neural tissues, referred here as neuroinflammation, along with different detrimental glial cell responses to stress conditions and neurodegenerative features. Moreover, diabetes resembles accelerated aging, further increasing the risk of developing age-linked neurodegenerative disorders. As such, the most common and disabling diabetic comorbidities, namely diabetic retinopathy, peripheral neuropathy, and cognitive decline, are intimately associated with neurodegeneration. As described in aging and other neurological disorders, glial cell alterations such as microglial, astrocyte, and Müller cell increased reactivity and dysfunctionality, myelin loss and Schwann cell alterations have been broadly described in diabetes in both human and animal models, where they are key contributors to chronic noxious inflammation of neural tissues within the PNS and CNS. In this review, we aim to describe in-depth the common and unique aspects underlying glial cell changes observed across the three main diabetic complications, with the goal of uncovering shared glial cells alterations and common pathological mechanisms that will enable the discovery of potential targets to limit neuroinflammation and prevent neurodegeneration in all three diabetic complications. Diabetes and its complications are already a public health concern due to its rapidly increasing incidence, and thus its health and economic impact. Hence, understanding the key role that glial cells play in the pathogenesis underlying peripheral neuropathy, retinopathy, and cognitive decline in diabetes will provide us with novel therapeutic approaches to tackle diabetic-associated neurodegeneration.

Baseline characteristics associated with the incidence of intraocular inflammation after the intravitreous injection of brolucizumab

PURPOSE

To investigate baseline characteristics associated with the incidence of intraocular inflammation (IOI) after the intravitreal injection of brolucizumab (IVBr) for the treatment of neovascular age-related macular degeneration (nAMD).

METHODS

This retrospective study included 66 eyes of 62 consecutive patients with nAMD who received IVBr (18 eyes were treatment naïve and 48 eyes had switched from other anti-vascular endothelial growth factor [VEGF] therapy). Baseline clinical characteristics were compared in non-IOI and IOI groups.

RESULTS

Although a dry macula was achieved at a high rate even 6 months after IVBr, IOI occurred in 8 of 66 eyes (12.1%; all had switched therapy) during the study period. Baseline characteristics including age, sex, nAMD type, lens status, visual acuity, central macular thickness, and a history of diabetes did not differ between the groups. The number of previous anti-VEGF injections before IVBr was greater in the IOI group (P = 0.004), and the ratio of patients with a laser flare-cell photometry (LFCP) value over 15 photon count per millisecond (pc/ms) was higher in the IOI group (P = 0.017). Multivariate logistic regression analysis showed that a greater number of previous anti-VEGF injections (odds ratio [OR]: 1.12, P = 0.006; area under the curve: 0.82, cut-off score: 14.0) and an LFCP value over 15 pc/ms (OR: 81.6, P = 0.031) were significantly associated with the incidence of IOI after IVBr.

CONCLUSION

A number of previous anti-VEGF injections greater than 14 and an LFCP value more than 15 pc/ms might be useful predictors of the incidence of IOI after IVBr in eyes with nAMD.

Macular changes following cataract surgery in eyes with early diabetic retinopathy: an OCT and OCT angiography study

Background

To evaluate changes in macular status and choroidal thickness (CT) following phacoemulsification in patients with mild to moderate nonproliferative diabetic retinopathy (NPDR) using optical coherence tomography.

Methods

In this prospective study, all of the patients underwent uncomplicated phacoemulsification. Retinal superficial capillary plexus vascular density (SCP-VD), macular thickness (MT), and CT were measured pre- and postoperatively.

Results

Twenty-two eyes of 22 cataract patients with mild to moderate NPDR without diabetic macular edema (DME) and 22 controls were enrolled. BCVA increased in two groups at 3 months postoperatively. At 1 and 3 months postoperatively, SCP-VD in the diabetic retinopathy (DR) group significantly increased; changes in SCP-VD in parafovea were significantly greater in the DR group than in the control group. MT and CT in the DR group significantly increased at all visits postoperatively in the fovea and perifovea. Changes in parafoveal MT were significantly greater in the DR group than in the control group at all visits postoperatively. Changes in CT and MT in the fovea were significantly greater in patients with DR than in the controls 1 and 3 months postoperatively.

Conclusion

Uncomplicated phacoemulsification resulted in greater increases in SCP-VD, MT and CT in patients with early DR without preoperative DME than in controls.

Immune Mediators Profiles in the Aqueous Humor of Patients with Simple Diabetic Retinopathy

Various immune mediators identified to date are associated with the development of advanced forms of diabetic retinopathy (DR), such as proliferative DR and diabetic macular edema, although the exact pathophysiological mechanisms of early stages of DR such as simple DR remain unclear. We determined the immune mediator profile in the aqueous humor of eyes with simple DR. Fifteen eyes of fifteen patients with simple DR were studied. Twenty-two eyes of twenty-two patients with cataracts and no DR served as controls. Undiluted aqueous humor samples were collected, and a cytometric bead array was used to determine the aqueous humor concentrations of 32 immune mediators comprising 13 interleukins (IL), interferon-γ, interferon-γ-inducible protein-10 (IP-10), monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1α, MIP-1β, regulated on activation, normal T cell expressed and secreted (RANTES), monokine induced by interferon-γ, basic fibroblast growth factor (bFGF), Fas ligand, granzyme A, granzyme B, interferon-inducible T-cell alpha chemoattractant (ITAC), fractalkine, granulocyte macrophage colony-stimulating factor, granulocyte colony-stimulating factor (G-CSF), vascular endothelial growth factor (VEGF), angiogenin, tumor necrosis factor-α, and CD40 ligand. Among the 32 immune mediators, 10 immune mediators, including bFGF, CD40 ligand, fractalkine, G-CSF, IL-6, IL-8, MIP-α, MIP-1β, and VEGF, showed significantly higher aqueous humor concentrations and the Fas ligand had significantly lower concentration (p < 0.05) in eyes with simple DR compared with control eyes. Of these 10 cytokines with significant concentration alteration, protein-protein interaction analysis revealed that 8 established an intricate interaction network. Various immune mediators may contribute to the pathogenesis of simple DR. Attention should be given to the concentrations of immune mediators in ocular fluids even in simple DR. Large-scale studies are warranted to assess whether altered aqueous humor concentrations of these 10 immune mediators are associated with an increased risk of progression to advanced stages of DR.

Association of a Bioimpedance Profile with Optical Coherence Tomography Features in Diabetic Macular Edema

We examined the association between bioimpedance profiles and optical coherence tomography (OCT) features in patients with diabetic macular edema (DME). This cross-sectional study included 100 eyes of 100 patients with type 2 diabetes mellitus. The systemic fluid status was assessed using extracellular water-to-total body water ratio (ECW/TBW) and phase angle (PhA), which was measured using bioimpedance equipment. ECW/TBW was higher in the DR (diabetic retinopathy) with DME group than in the no DR and DR without DME groups (p = 0.007 and p = 0.047, respectively); however, no significant difference was observed between the no DR and DR without DME groups. The PhA values were significantly lower in the DR with DME group (5.45 ± 0.84) than in the no DR (6.69 ± 0.69) and DR without DME groups (6.05 ± 1.15) (p < 0.001, p = 0.032, respectively). The presence of multiple HRF (hyper-reflective foci) was associated with a significantly higher ECW/TBW (p = 0.001). In the group with the most significant HRF, PhA was lower than in those with none or moderate amounts of HRF (p < 0.05). Bioimpedance fluid profiles of patients with OCT features of DME suggest a connection between the overall systemic state, including fluid status and DME development. Further research is required to fully understand and utilize this information for effective clinical assessment and treatment planning.

Pro re nata Treatment of Diabetic Macular Edema with Cycles of Three Injections of Anti-vascular Endothelial Growth Factor Injections

PURPOSE

The purpose of this study was to report the visual and anatomic results at 12 and 24 months using the protocol of 3 monthly pro re nata (PRN) injections for diabetic macular edema (DME).

METHODS

This was a retrospective chart review of 97 eyes with DME treated with a protocol of cycles consisting of 3 monthly injections of anti-vascular endothelial growth factor drugs on a PRN basis. Change in visual acuity was the main outcome measure. Macular thickness, number of injections, cycles, and visits in years 1 and 2 of follow-up were secondary outcomes.

RESULTS

Ninety-six patients with a mean age of 60.9 ± 9.96 years were followed for a mean of 22.17 ± 12.30 months. Ninety-two (95.9%), 3 (3%), and 1 (1%) patients were started on bevacizumab, ranibizumab, and aflibercept, respectively. Of bevacizumab patients, 17 (18.2%) were eventually switched to aflibercept. The mean 12-month improvement (standard deviation [SD]) was + 3.3 (17.4) letters (95% confidence interval [CI] = +0.36-+7.05, P < 0.001) after an average (SD) of 5.97 (2.98) injections over a mean (SD) of 1.7 (1.0) three-injection cycles. The mean 24-month improvement (SD) was + 5.6 (13.0) letters (95% CI: -0.28-11.05, P = 0.0186) after an average (SD) of 8.72 (6.31) injections over a mean (SD) of 2.9 (2.1) three-injection cycles. The mean central macular thickness (SD) at baseline, 12 months, and 24 months was 374 ± 120, 322 ± 88, and 305 ± 70 µm. Optical coherence tomography was fluid free at 12 and 24 months in 27.6% and 46% of eyes, respectively.

CONCLUSION

Comparable to real-world studies, this protocol can stabilize or improve vision in more than 85% of DME patients over 24 months. The most important factor in improvement of vision is increasing number of injections and visits.

Faricimab for Diabetic Macular Edema in Patients Refractory to Ranibizumab or Aflibercept

Background and Objectives: Faricimab is the first intravitreal injection of vascular endothelial growth factor-A and angiopoietin-2 bispecific monoclonal antibody. Here, we evaluate the functional and anatomical outcomes of faricimab treatment in patients with diabetic macular edema (DME) that was refractory to ranibizumab or aflibercept. Materials and Methods: We performed a retrospective, observational, consecutive-case study of patients who had DME that was refractory to treatment with ranibizumab or aflibercept and were treated with faricimab between July 2022 and January 2023 under a pro re nata regimen. All the participants were followed for ≥4 months after the initiation of faricimab. The primary outcome was a recurrence interval of ≥12 weeks, and the secondary outcomes were the changes in best-corrected visual acuity (BCVA) and central macular thickness (CMT). Results: We analyzed 18 eyes of 18 patients. The mean recurrence interval of previous anti-VEGF injection was 5.8 ± 2.5 weeks, which was significantly extended to 10.8 ± 4.9 weeks (p = 0.0005) by the switch to faricimab. Eight patients (44.4%) achieved a recurrence interval of ≥12 weeks. A history of subtenon injection of triamcinolone acetonide (p = 0.0034) and the presence of disorganization of the retinal inner layers (p = 0.0326) were found to be significantly associated with a recurrence interval of <12 weeks. The mean BCVAs were 0.23 ± 0.28 logMAR and 0.19 ± 0.23 logMAR, and the mean CMTs were 473.8 ± 222.0 µm and 381.3 ± 219.4 µm at baseline and 4 months, respectively, but these changes were not statistically significant. None of the patients experienced serious adverse events. Conclusions: Faricimab may extend the treatment interval for patients with DME that is refractory to ranibizumab or aflibercept. DME previously treated with the subtenon injection of triamcinolone acetonide or associated with disorganization of the retinal inner layers may be less likely to be associated with a longer recurrence interval after switching to faricimab.

Transcriptomic Profiling Reveals Chemokine CXCL1 as a Mediator for Neutrophil Recruitment Associated With Blood-Retinal Barrier Alteration in Diabetic Retinopathy

Inflammation plays an important role in the pathogenesis of diabetic retinopathy (DR). To precisely define the inflammatory mediators, we examined the transcriptomic profile of human retinal endothelial cells exposed to advanced glycation end products, which revealed the neutrophil chemoattractant chemokine CXCL1 as one of the top genes upregulated. The effect of neutrophils in the alteration of the blood-retinal barrier (BRB) was further assessed in wild-type C57BL/6J mice intravitreally injected with recombinant CXCL1 as well as in streptozotocin-induced diabetic mice. Both intravitreally CXCL1-injected and diabetic animals showed significantly increased retinal vascular permeability, with significant increase in infiltration of neutrophils and monocytes in retinas and increased expression of chemokines and their receptors, proteases, and adhesion molecules. Treatment with Ly6G antibody for neutrophil depletion in both diabetic mice as well as CXCL1-injected animals showed significantly decreased retinal vascular permeability accompanied by decreased infiltration of neutrophils and monocytes and decreased expression of cytokines and proteases. CXCL1 level was significantly increased in the serum samples of patients with DR compared with samples of those without diabetes. These data reveal a novel mechanism by which the chemokine CXCL1, through neutrophil recruitment, alters the BRB in DR and, thus, serves as a potential novel therapeutic target.

ARTICLE HIGHLIGHTS

Intravitreal CXCL1 injection and diabetes result in increased retinal vascular permeability with neutrophil and monocyte recruitment. Ly6G antibody treatment for neutrophil depletion in both animal models showed decreased retinal permeability and decreased cytokine expression. CXCL1 is produced by retinal endothelial cells, pericytes, and astrocytes. CXCL1 level is significantly increased in serum samples of patients with diabetic retinopathy. CXCL1, through neutrophil recruitment, alters the blood-retinal barrier in diabetic retinopathy and, thus, may be used as a therapeutic target.

Relationship between Diabetic Nephropathy and Development of Diabetic Macular Edema in Addition to Diabetic Retinopathy

This study aimed to examine the relationship between diabetic retinopathy (DR) and systemic factors. We evaluated 261 patients (143 men, 118 women, aged 70.1 ± 10.1 years) with type 2 diabetes. All participants underwent a fundus examination, fundus photography using spectral domain optical coherence tomography (SD-OCT), and blood tests. For glycated hemoglobin (HbA1c) levels, the average and highest values in the past were used. We observed DR in 127 (70 men and 57 women) of 261 patients. Logistic regression analyses revealed a significant correlation between DR development and the duration of diabetes (OR = 2.40; 95% CI: 1.50), average HbA1c level (OR = 5.57; 95% CI: 1.27, 24.4), highest HbA1c level (OR = 2.46; 95% CI: 1.12, 5.38), and grade of diabetic nephropathy (DN) (OR = 6.23; 95% CI: 2.70, 14.4). Regression analyses revealed a significant correlation between the severity of DR and duration of diabetes (t = -6.66; 95% CI: 0.21, 0.39), average HbA1c level (t = 2.59; 95% CI: 0.14, 1.02), and severity of DN (t = 6.10; 95% CI: 0.49, 0.97). Logistic regression analyses revealed a significant correlation between diabetic macular edema (DME) development and DN grade (OR = 2.22; 95% CI: 1.33, 3.69). DN grade correlates with the development of DR and DME, and decreased renal function predicts the onset of DR.

Pathological Neurovascular Unit Mapping onto Multimodal Imaging in Diabetic Macular Edema

Diabetic retinopathy is a form of diabetic microangiopathy, and vascular hyperpermeability in the macula leads to retinal thickening and concomitant reduction of visual acuity in diabetic macular edema (DME). In this review, we discuss multimodal fundus imaging, comparing the pathogenesis and interventions. Clinicians diagnose DME using two major criteria, clinically significant macular edema by fundus examination and center-involving diabetic macular edema using optical coherence tomography (OCT), to determine the appropriate treatment. In addition to fundus photography, fluorescein angiography (FA) is a classical modality to evaluate morphological and functional changes in retinal capillaries, e.g., microaneurysms, capillary nonperfusion, and fluorescein leakage. Recently, optical coherence tomography angiography (OCTA) has allowed us to evaluate the three-dimensional structure of the retinal vasculature and newly demonstrated that lamellar capillary nonperfusion in the deep layer is associated with retinal edema. The clinical application of OCT has accelerated our understanding of various neuronal damages in DME. Retinal thickness measured by OCT enables us to quantitatively assess therapeutic effects. Sectional OCT images depict the deformation of neural tissues, e.g., cystoid macular edema, serous retinal detachment, and sponge-like retinal swelling. The disorganization of retinal inner layers (DRIL) and foveal photoreceptor damage, biomarkers of neurodegeneration, are associated with visual impairment. Fundus autofluorescence derives from the retinal pigment epithelium (RPE) and its qualitative and quantitative changes suggest that the RPE damage contributes to the neuronal changes in DME. These clinical findings on multimodal imaging help to elucidate the pathology in the neurovascular units and lead to the next generation of clinical and translational research in DME.

Circulatory Biomarkers and Diabetic Retinopathy in Racial and Ethnic Populations

Clinical staging systems for diagnosis and treatment of diabetic retinopathy (DR) must closely relate to endpoints that are both relevant for patients and feasible for physicians to implement. Current DR staging systems for clinical eye care and research provide detailed phenotypic characterization to predict patient outcomes in diabetes but have limitations. Biochemical biomarkers provide a rich pool of potential candidates for new DR staging systems that can be readily measured in accessible fluids. Circulating biomarkers that are specific to the retina and relate to angiogenesis and inflammation have been suggested as relevant for DR. Although there is a lack of multi-ethnic studies evaluating circulatory biomarkers in DR, variability in circulatory biomarkers have been reported in people from different ethnic and racial backgrounds. Therefore, there is a need for future studies to evaluate individual or combinations of biomarkers in diverse populations with DR from different ethnic and racial backgrounds.

Diabetic Retinopathy: Soluble and Imaging Ocular Biomarkers

Diabetic retinopathy (DR), the most common microvascular complication of diabetes mellitus, represents the leading cause of acquired blindness in the working-age population. Due to the potential absence of symptoms in the early stages of the disease, the identification of clinical biomarkers can have a crucial role in the early diagnosis of DR as well as for the detection of prognostic factors. In particular, imaging techniques are fundamental tools for screening, diagnosis, classification, monitoring, treatment planning and prognostic assessment in DR. In this context, the identification of ocular and systemic biomarkers is crucial to facilitate the risk stratification of diabetic patients; moreover, reliable biomarkers could provide prognostic information on disease progression as well as assist in predicting a patient's response to therapy. In this context, this review aimed to provide an updated and comprehensive overview of the soluble and anatomical biomarkers associated with DR.

Mechanisms of macular edema

Macular edema is the pathological accumulation of fluid in the central retina. It is a complication of many retinal diseases, including diabetic retinopathy, retinal vascular occlusions and uveitis, among others. Macular edema causes decreased visual acuity and, when chronic or refractory, can cause severe and permanent visual impairment and blindness. In most instances, it develops due to dysregulation of the blood-retinal barrier which permits infiltration of the retinal tissue by proteins and other solutes that are normally retained in the blood. The increase in osmotic pressure in the tissue drives fluid accumulation. Current treatments include vascular endothelial growth factor blockers, corticosteroids, and non-steroidal anti-inflammatory drugs. These treatments target vasoactive and inflammatory mediators that cause disruption to the blood-retinal barrier. In this review, a clinical overview of macular edema is provided, mechanisms of disease are discussed, highlighting processes targeted by current treatments, and areas of opportunity for future research are identified.

Current Treatments and Innovations in Diabetic Retinopathy and Diabetic Macular Edema

Diabetic retinopathy (DR) is one of the leading causes of blindness worldwide. Multiple treatment options have been used over time to attempt to modify the natural progression of the disease in both proliferative diabetic retinopathy (PDR) and diabetic macular edema (DME). These two retinal complications are the result of microvascular occlusions and vascular hyperpermeability and are considered one of the leading causes of irreversible blindness in patients of working age. It is now well demonstrated that PDR and DME are associated with increased levels of inflammatory and pro-angiogenic factors in the ocular compartment. To date, laser photocoagulation, vascular endothelial growth factor (VEGF) inhibitors, and corticosteroids have demonstrated efficacy in their treatment in large randomized controlled trials and in real-life observational studies. This manuscript aims to provide a comprehensive review of current treatments, including the main drugs used in diabetic pathologic manifestations, as well as new therapeutic alternatives, such as extended-release intraocular devices.

Haller Layer Thickness after Intravitreal Aflibercept Injection in Diabetic Macular Edema: 1 Month Change

Purpose: To analyze the changes in subfoveal Haller layer thickness (SFHT), subfoveal choroidal thickness (SFCT), and central macular thickness (CMT) after intravitreal aflibercept injection.Methods: This was a retrospective analysis of 36 diabetic macular edema patients who underwent intravitreal aflibercept injection between December 2016 and June 2021. The SFHT, SFCT, and CMT before and 1 month after the injection were compared using spectral-domain optical coherence tomography.Results: Mean baseline SFHT, SFCT, and CMT were 214.28 ± 80.00 μm, 307.89 ± 96.30 μm, and 525.64 ± 133.24 μm, which were reduced 1 month after the injection to 199.56 ± 75.76 μm, 290.36 ± 94.63 μm, and 409.72 ± 98.45 μm, respectively (<i>p</i> = 0.001, < 0.001, and < 0.001, respectively). There was a significant correlation between baseline SFHT and 1-month post-injection best-corrected visual acuity (BCVA), while thicker subfoveal Haller layers before the injection were associated with better BCVA after the injection (ρ = −0.342; <i>p</i> = 0.041).Conclusions: In diabetic macular edema patients, SFHT, SFCT, and CMT decreased significantly over 1 month after the first intravitreal aflibercept injection. Greater SFHT before the injection was a good short-term predictor of BCVA after injection.

Development of an anti-oxidative intraocular irrigating solution based on reactive persulfides

Anti-oxidative intraocular irrigating solutions (IISs) based on reactive persulfides, such as oxidized glutathione disulfide (GSSG), are commonly used worldwide. However, even with GSSG-based IISs, it has been shown that oxidative stress can occur during surgery, posing a risk to intraocular tissues. This study compared two IISs: one containing GSSG and one containing an oxidized glutathione trisulfide (GSSSG). Experimental in vivo irrigation with the IISs in rabbits showed that there was less leakage into the anterior chamber of rabbit serum albumin during perfusion with a 300-μM GSSSG IIS than with a 300-μM GSSG IIS. Experimental in vivo cataract surgery in rabbits showed that aqueous flare was suppressed 3 days after surgery with a 600-μM GSSSG IIS, but not with a 300-μM GSSSG or 300-μM GSSG IIS. Furthermore, an in vitro experiment, without any live tissue, showed that reactive oxygen species were suppressed more strongly with a 600-μM GSSSG IIS than with a 300-μM GSSG IIS. Thus, this study found that novel IISs based on GSSSG had anti-inflammatory and anti-oxidative effects during and after intraocular surgery and may decrease the rate of complications after surgery.

Diabetic retinopathy screening in the emerging era of artificial intelligence

Diabetic retinopathy is a frequent complication in diabetes and a leading cause of visual impairment. Regular eye screening is imperative to detect sight-threatening stages of diabetic retinopathy such as proliferative diabetic retinopathy and diabetic macular oedema in order to treat these before irreversible visual loss occurs. Screening is cost-effective and has been implemented in various countries in Europe and elsewhere. Along with optimised diabetes care, this has substantially reduced the risk of visual loss. Nevertheless, the growing number of patients with diabetes poses an increasing burden on healthcare systems and automated solutions are needed to alleviate the task of screening and improve diagnostic accuracy. Deep learning by convolutional neural networks is an optimised branch of artificial intelligence that is particularly well suited to automated image analysis. Pivotal studies have demonstrated high sensitivity and specificity for classifying advanced stages of diabetic retinopathy and identifying diabetic macular oedema in optical coherence tomography scans. Based on this, different algorithms have obtained regulatory approval for clinical use and have recently been implemented to some extent in a few countries. Handheld mobile devices are another promising option for self-monitoring, but so far they have not demonstrated comparable image quality to that of fundus photography using non-portable retinal cameras, which is the gold standard for diabetic retinopathy screening. Such technology has the potential to be integrated in telemedicine-based screening programmes, enabling self-captured retinal images to be transferred virtually to reading centres for analysis and planning of further steps. While emerging technologies have shown a lot of promise, clinical implementation has been sparse. Legal obstacles and difficulties in software integration may partly explain this, but it may also indicate that existing algorithms may not necessarily integrate well with national screening initiatives, which often differ substantially between countries.

Role of Autotaxin in High Glucose-Induced Human ARPE-19 Cells

Autotaxin (ATX) is an enzymatic with lysophospholipase D (lysoPLD) activity. We investigated the role of ATX in high glucose (HG)-induced human retinal pigment epithelial (ARPE-19) cells to explore the pathogenesis of diabetic retinopathy (DR). We performed a quantitative real-time polymerase chain reaction, Western blotting, immunocytochemistry, enzyme-linked immunosorbent assay, cell permeability assay, and transepithelial electrical resistance measurement in HG-induced ARPE-19 cells and compared their results with those of normal glucose and osmotic pressure controls. ATX expression and its lysoPLD activity, barrier function, and expression of vascular endothelial growth factor receptors VEGFR-1 and VEGFR-2 were downregulated, while fibrotic responses, cytoskeletal reorganization, and transforming growth factor-β expression were upregulated, in the HG group. Our results suggest that HG induces intracellular ATX downregulation, barrier dysfunction, and fibrosis, which are involved in early DR and can be targeted for DR treatment.

Neuroinflammation and neurodegeneration in diabetic retinopathy

Diabetic retinopathy (DR) is the most common complication of diabetes and has been historically regarded as a microangiopathic disease. Now, the paradigm is shifting toward a more comprehensive view of diabetic retinal disease (DRD) as a tissue-specific neurovascular complication, in which persistently high glycemia causes not only microvascular damage and ischemia but also intraretinal inflammation and neuronal degeneration. Despite the increasing knowledge on the pathogenic pathways involved in DR, currently approved treatments are focused only on its late-stage vasculopathic complications, and a single molecular target, vascular endothelial growth factor (VEGF), has been extensively studied, leading to drug development and approval. In this review, we discuss the state of the art of research on neuroinflammation and neurodegeneration in diabetes, with a focus on pathophysiological studies on human subjects, in vivo imaging biomarkers, and clinical trials on novel therapeutic options.

Intravitreal aflibercept for diabetic macular edema in real-world clinical practice in Japan: 24-month outcomes

Purpose

To report the safety and effectiveness of intravitreal aflibercept (IVT-AFL) for diabetic macular edema (DME) in the real-world clinical practice setting in Japan.

Methods

In this prospective, multicenter, observational, post-marketing surveillance, patients with DME newly receiving IVT-AFL were enrolled. During a 24-month follow-up, the primary outcome was the occurrence of safety events. Other pre-specified endpoints were effectiveness indicators, such as best-corrected visual acuity (BCVA), central retinal thickness, and injection frequency.

Results

In total, 646 patients administered at least one IVT-AFL injection were included in the safety analysis. During the follow-up period, adverse events occurred in 42 patients (6.50%), whereas adverse drug reactions occurred in 12 (1.86%). In the 12 patients who had adverse drug reactions, seven events occurred in seven patients within the first month of the most recent injection. In addition, 622 patients were included in the effectiveness analysis set. The number of injections over 24 months was 3.6 ± 3.0 (mean ± standard deviation [SD]). BCVA (logarithm of the minimum angle of resolution) was 0.437 ± 0.362 (mean ± SD) (n = 622) at baseline and 0.321 ± 0.348 (n = 177) after 24 months of treatment with IVT-AFL. Central retinal thickness was 440.8 ± 134.2 μm (mean ± SD) (n = 444) at baseline and 355.5 ± 126.4 μm (n = 140) at 24 months.

Conclusion

Routine administration of IVT-AFL for DME was not associated with new safety concerns, and BCVA outcomes were maintained over 24 months in the real-world setting. Nonetheless, patients in this real-world setting received fewer injections than those in clinical trials, suggesting that a margin for improvement exists in clinical practice.

Trial registration

ClinicalTrials.gov: NCT02425501.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-022-05703-9.

Factors predicting the treatment frequency of ranibizumab injections during the second year in diabetic macular edema

PURPOSE

To investigate the predictors of annual treatment frequency in the second year of pro re nata (PRN) intravitreal ranibizumab (IVR) injections for diabetic macular edema (DME).

STUDY DESIGN

A retrospective study.

METHODS

We reviewed 65 eyes of 60 patients with center-involved DME who received PRN IVR injections after 3 monthly loading doses. The central subfield thickness (CST) and qualitative findings were assessed on the spectral domain optical coherence tomography (SD-OCT) images. We then investigated whether the parameters at the baseline or at the 12-month visit were associated with treatment frequency in the second year.

RESULTS

The number of ranibizumab injections decreased from 6 (4-8) during the first year to 2 (0-3) during the second year (P < .001). The injection numbers during the first year (ρ = 0.259, P = .037) but not during the second year (ρ = 0.152, P = .226) were modestly related to the logarithm of the minimum angle of resolution (logMAR) improvement at 24 months. Multivariate analyses revealed that the CST (β = 0.336, P = .005) and hyperreflective walls in the foveal cystoid spaces (β = 0.273, P = .020) at baseline were associated with the number of IVR injections during the second year. The treatment frequency during the second year was also related to the CST (β = 0.266, P = .012), hyperreflective walls (β = 0.394, P = .002), and cumulative doses of ranibizumab injections (β = 0.294, P = .006) at the 12-month visit.

CONCLUSIONS

The cumulative doses of ranibizumab injections, CST, and hyperreflective walls in the foveal cystoid spaces at the 12-month visit are designated predictors of the treatment frequency of ranibizumab injections during the second year in DME.

Sulpiride-induced hyperprolactinaemia increases retinal vasoinhibin and protects against diabetic retinopathy in rats

Excessive vasopermeability and angiogenesis compromise vision in diabetic macular oedema (DME) and diabetic retinopathy (DR). Vasoinhibin is a fragment of the hormone prolactin (PRL) that inhibits diabetes-induced retinal hypervasopermeability and ischaemia-induced retinal angiogenesis in rodents. Hyperprolactinaemia generated by the dopamine D2 receptor antagonist, levosulpiride, is associated with higher levels of vasoinhibin in the vitreous of patients with DR, implying a beneficial outcome due to vasoinhibin-mediated inhibition of retinal vascular alterations. Here, we tested whether hyperprolactinaemia induced by racemic sulpiride increases intraocular vasoinhibin levels and inhibits retinal hypervasopermeability in diabetic rats. Diabetes was generated with streptozotocin and, 4 weeks later, rats were treated for 2 weeks with sulpiride or osmotic minipumps delivering PRL. ELISA, Western blot, and Evans blue assay were used to evaluate serum PRL, retinal vasoinhibin, and retinal vasopermeability, respectively. Hyperprolactinaemia in response to sulpiride or exogenous PRL was associated with increased levels of vasoinhibin in the retina and reduced retinal hypervasopermeability. Furthermore, sulpiride decreased retinal haemorrhages in response to the intravitreal administration of vascular endothelial growth factor (VEGF). Neither sulpiride nor exogenous PRL modified blood glucose levels or bodyweight. We conclude that sulpiride-induced hyperprolactinaemia inhibits the diabetes- and VEGF-mediated increase in retinal vasopermeability by promoting the intraocular conversion of endogenous PRL to vasoinhibin. These findings support the therapeutic potential of sulpiride and its levorotatory enantiomer, levosulpiride, against DME and DR.

Vitreous cytokine levels following the administration of a single 0.19 mg fluocinolone acetonide (ILUVIEN®) implant in patients with refractory diabetic macular edema (DME)-results from the ILUVIT study

Purpose

To investigate the changes in vitreous inflammatory and angiogenic cytokine levels, primarily interleukin-(IL)-6, following intravitreal injection of the 0.19 mg fluocinolone acetonide (FAc, ILUVIEN®) implant in patients with diabetic macular edema.

Methods

A single-center phase IV study involving 12 patients’ eyes with diabetic macular edema. Vitreous fluid samples were obtained prior to intravitreal injection of the fluocinolone acetonide implant and then again over a 6-month period. Vitreous samples were examined using a cytometric bead array to measure IL-6, IL-8, IP-10, MCP-1, VEGF, and CD54. PIGF and PEDF were measured using an enzyme-linked immunosorbent assay. Changes in the cytokine and chemokine expression patterns were analyzed. Clinical parameters such as BCVA and center point thickness (CPT) were also examined.

Results

There were mean reductions in all parameters between baseline and month 6. Significant changes (p < 0.05 versus baseline) were observed in the expression of IL-6, IP-10, MCP-1, and CD54 following the administration of fluocinolone acetonide implant. VEGF and PIGF increased at month 1 before declining at month 6, though this trend was not significant. CPT decreased rapidly between screening and the first follow-up visit, and this decrease was sustained. BCVA remained relatively stable throughout.

Conclusion

This study demonstrated changes in vitreous inflammatory and angiogenic cytokine levels following intravitreal injection of the FAc implant in patients with diabetic macular edema. Data show that the fluocinolone acetonide implant led to rapid and sustained reductions of some inflammatory cytokines with improvement of the overall clinical picture.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-022-05564-2.

The intercapillary space spectrum as a marker of diabetic retinopathy severity on optical coherence tomography angiography

Microcirculatory disturbance plays a pivotal role in the pathogenesis in diabetic retinopathy (DR). We retrospectively quantified the total counts and morphological features of intercapillary spaces, i.e., intercapillary areas and nonperfusion areas (NPAs), on swept-source optical coherence tomography angiography (SS-OCTA) images and to evaluate their associations with DR severity grades. We acquired 3 × 3 mm OCTA images in 75 eyes of 62 diabetic patients and 22 eyes of 22 nondiabetic subjects. In the en-face superficial images within the central 2 mm, the areas enclosed by retinal vessels were automatically detected. Their total numbers decreased in some eyes with no apparent retinopathy and most eyes with DR, which allowed us to discriminate diabetic subjects from nondiabetic subjects [area under the receiver operating characteristic curve (AUC) = 0.907]. The areas and area/perimeter ratios continuously increased in DR, indicating a continuum between healthy intercapillary areas and NPAs. The number of intercapillary spaces with a high area/perimeter ratio increased according to DR severity, which showed modest performance in discriminating moderate NPDR or higher grades (AUC = 0.868). These quantified parameters of intercapillary spaces can feasibly be used for the early detection of microcirculatory impairment and the diagnosis of referable DR.

Changes in aqueous and vitreous inflammatory cytokine levels in diabetic macular oedema: a systematic review and meta-analysis

Diabetic macular oedema (DME) is considered a chronic inflammatory disease associated with aberrations in many intraocular cytokines. Studies assessing the role of these cytokines as biomarkers in the diagnosis and management of DME have demonstrated inconsistent findings. We quantitatively summarized data related to 116 candidate aqueous and vitreous inflammatory cytokines as biomarkers in DME. A systematic search without year limitation was performed up to 19 October 2020. Studies were included if they provided data on aqueous or vitreous cytokine concentrations in patients with DME. Effect sizes were generated as standardized mean differences (SMDs) of cytokine concentrations between patients with DME and controls. Data were extracted from 128 studies that included 4163 study eyes with DME and 1281 control eyes. Concentrations (standard mean difference, 95% confidence interval and p-value) of aqueous IL-6 (1.28, 0.57-2.00, p = 0.004), IL-8 (1.06, 0.74-1.39, p < 0.00001), MCP-1 (1.36, 0.57-2.16, p = 0.0008) and VEGF (1.31, 1.01-1.62, p < 0.00001) and vitreous VEGF (2.27, 1.55-2.99, p < 0.00001) were significantly higher in patients with DME (n = 4163) compared to healthy controls (n = 1281). No differences, failed sensitivity analyses or insufficient data were found between patients with DME and healthy controls for the concentrations of the remaining cytokines. This analysis implicates multiple cytokine biomarker candidates other than VEGF in DME and clarifies previously reported inconsistent associations. As the therapeutic options for DME expand to include multiple agents with multiple targets, it will be critical to manage the treatment burden with tailored therapy that optimizes outcomes and minimizes treatment burden. Intraocular cytokines have the promise of providing a robust individualized assessment of disease status and response to therapy. We have identified key candidate cytokines that may serve as biomarkers in individualized treatment algorithms.

LRG1 as a novel therapeutic target in eye disease

Retinal and choroidal diseases are major causes of blindness and visual impairment in the developed world and on the rise due to an ageing population and diabetes epidemic. Standard of care is centred around blockade of vascular endothelial growth factor (VEGF), but despite having halved the number of patients losing sight, a high rate of patient non-response and loss of efficacy over time are key challenges. Dysregulation of vascular homoeostasis, coupled with fibrosis and inflammation, are major culprits driving sight-threatening eye diseases. Improving our knowledge of these pathological processes should inform the development of new drugs to address the current clinical challenges for patients. Leucine-rich α-2 glycoprotein 1 (LRG1) is an emerging key player in vascular dysfunction, inflammation and fibrosis. Under physiological conditions, LRG1 is constitutively expressed by the liver and granulocytes, but little is known about its normal biological function. In pathological scenarios, such as diabetic retinopathy (DR) and neovascular age-related macular degeneration (nvAMD), its expression is ectopically upregulated and it acquires a much better understood pathogenic role. Context-dependent modulation of the transforming growth-factor β (TGFβ) pathway is one of the main activities of LRG1, but additional roles have recently been emerging. This review aims to highlight the clinical and pre-clinical evidence for the pathogenic contribution of LRG1 to vascular retinopathies, as well as extrapolate from other diseases, functions which may be relevant to eye disease. Finally, we will provide a current update on the development of anti-LRG1 therapies for the treatment of nvAMD.

Clinical Features of Patients with Opacification of Hydrophilic Acrylic Intraocular Lens in Neovascular Glaucoma

Purpose: To report the clinical features of patients with opacification of hydrophilic acrylic intraocular lens (IOL) after cataract surgery in neovascular glaucoma.Methods: This retrospective case series included 11 eyes of 10 patients with IOL opacification and neovascular glaucoma (NVG) between January 2006 and December 2010. We included and analyzed cases with opacification of hydrophilic acrylic IOL. An IOL exchange was performed in three cases, and the explanted IOLs were examined grossly and evaluated by light microscopy. Sagittal sections of the optics of the IOLs were evaluated by Von Kossa staining, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX).Results: All 11 eyes of 10 patients were implanted with hydrophilic acrylic IOLs. In addition, there were no cases of hydrophobic acrylic IOL opacification. Nine patients of the 10 patients had diabetic retinopathy and one patient had central retinal artery occlusion. The mean period of IOL opacification after IOL implantation was 19.45 ± 8.52 months and the mean period of IOL opacification after the occurrence of NVG was 14.37 ± 8.51 months. The deposits of the explanted IOLs were shown to consist of calcium by von Kossa staining. The explanted IOLs showed fine whitish irregular granular deposits on the entire anterior surface of the optics by SEM and the presence of calcium deposition was confirmed by EDX analysis.Conclusions: Care is required when using hydrophilic acrylic IOLs in patients with risk of neovascular glaucoma, such as those with diabetic retinopathy or central retinal artery occlusion.

Temporal variation of optical coherence tomography biomarkers as predictors of anti-VEGF treatment outcomes in diabetic macular edema

PURPOSE

To report a longitudinal analysis of specific optical coherence tomography (OCT) features in eyes with diabetic macular edema (DME) treated with anti-VEGF.

METHODS

A total of 133 eyes of 103 consecutive patients with center-involving DME were included in the study. The eyes were treated between August 2008 and April 2019 with three monthly intravitreal anti-VEGF injections, either with or without prompt or deferred laser, followed by pro re nata (PRN) re-treatment. The following OCT biomarkers were evaluated: subfoveal neuroretinal detachment (SND) (defined as present (SND+) or absent (SND-)), hyperreflective retinal foci (HRF) number (defined as: absent/few(HRF-) or moderate/many (HRF+)), external limiting membrane (ELM) integrity, central macular thickness (CMT), and central retinal thickness (CRT). Changes in SND status and in the number of HRF were evaluated at each DME recurrence throughout the follow-up(FU) period. Mutual correlation among OCT biomarkers and their relationship with visual and anatomic outcomes were assessed both at baseline and over the FU period.

RESULTS

The mean FU was 71.2 months (SD 28.4; min. 12-max. 111). At baseline, the prevalence of SRD+ was 27.8% and a high number of HRF were detected in 41.4% of the eyes. A significant reduction in the number of HRF, CMT, CRT, and in the prevalence of SND was recorded in the post-loading phase (p-value <0.0001). In DME recurrences, the presence of SND+ and HRF+ was significantly more frequent in eyes with baseline SND+ and HRF+ compared to eyes presenting baseline SND- and HRF- (p-value <0.0001). No role of SND (p-value: 0.926) and HRF (p-value: 0.281) as baseline predictors of visual and anatomic outcomes was demonstrated, while a worse visual outcome was significantly correlated with a higher incidence of relapsing SND+ (p-value <0.0001) and HRF+ (p-value <0.0028) throughout the FU period.

CONCLUSION

In this study, SND and HRF were frequently present in DME recurrences with the same pattern exhibited at baseline, suggesting that these OCT biomarkers may characterize a specific pattern of DME that repeats over time. Moreover, the results suggested that the persistence and recurrence of SND and HRF may account for a decrease in visual function more than the baseline prevalence of these biomarkers. Further studies are required to confirm these findings.

Targeting Plasma Kallikrein With a Novel Bicyclic Peptide Inhibitor (THR-149) Reduces Retinal Thickening in a Diabetic Rat Model

Purpose

To investigate the effect of plasma kallikrein (PKal)-inhibition by THR-149 on preventing key pathologies associated with diabetic macular edema (DME) in a rat model.

Methods

Following streptozotocin-induced diabetes, THR-149 or its vehicle was administered in the rat via either a single intravitreal injection or three consecutive intravitreal injections (with a 1-week interval; both, 12.5 µg/eye). At 4 weeks post-diabetes, the effect of all groups was compared by histological analysis of Iba1-positive retinal inflammatory cells, inflammatory cytokines, vimentin-positive Müller cells, inwardly rectifying potassium and water homeostasis-related channels (Kir4.1 and AQP4, respectively), vascular leakage (fluorescein isothiocyanate-labeled bovine serum albumin), and retinal thickness.

Results

Single or repeated THR-149 injections resulted in reduced inflammation, as depicted by decreasing numbers and activation state of immune cells and IL-6 cytokine levels in the diabetic retina. The processes of reactive gliosis, vessel leakage, and retinal thickening were only significantly reduced after multiple THR-149 administrations. Individual retinal layer analysis showed that repeated THR-149 injections significantly decreased diabetes-induced thickening of the inner plexiform, inner nuclear, outer nuclear, and photoreceptor layers. At the glial-vascular interface, reduced Kir4.1-channel levels in the diabetic retina were restored to control non-diabetic levels in the presence of THR-149. In contrast, little or no effect of THR-149 was observed on the AQP4-channel levels.

Conclusions

These data demonstrate that repeated THR-149 administration reduces several DME-related key pathologies such as retinal thickening and neuropil disruption in the diabetic rat. These observations indicate that modulation of the PKal pathway using THR-149 has clinical potential to treat patients with DME.

Comparison of Inflammatory and Angiogenic Factors in the Aqueous Humor of Vitrectomized and Non-Vitrectomized Eyes in Diabetic Macular Edema Patients

Objectives: To compare the aqueous concentrations of inflammatory and angiogenetic factors in vitrectomized vs. non-vitrectomized eyes with diabetic macular edema (DME).

Methods: Aqueous samples were obtained from 107 eyes with DME before intravitreal injection of anti-VEGF, 36 eyes with previous pars plana vitrectomy (PPV) combined with pan-retinal endolaser photocoagulation (PRP), and 71 treatment-naïve. Interleukin (IL)-6, IL-8, interferon-induced protein (IP)-10, monocyte chemoattractant protein (MCP)-1, and vascular endothelial growth factor (VEGF) were measured by cytometric bead array (CBA). Optical coherence tomography (OCT) was used for measuring central retinal thickness (CRT).

Results: IL-6, IL-8, IP-10, and MCP-1 in aqueous humor of DME vitrectomized eyes were significantly higher than in non-vitrectomized DME eyes, while VEGF was lower than in non-vitrectomized DME eyes. VEGF in aqueous humor significantly correlated with CRT for DME in non-vitrectomized DME eyes. IL-6, IL-8, IP-10, and MCP-1 in aqueous humor were not significantly associated with VEGF for DME in vitrectomized eyes.

Conclusions: Inflammation might play an important role in the pathogenesis of DME in vitrectomized eyes. Moreover, inflammation might play a central role in the development of DME via the VEGF-independent pathway. Thus, anti-inflammatory therapy might be a strategy for DME in vitrectomized eyes.

Assessing the protective effects of cryptotanshinone on CoCl2‑induced hypoxia in RPE cells

The development of several retinal diseases is closely related to hypoxia. As a component of the Traditional Chinese medicine Salvia miltiorrhiza, the effects of cryptotanshinone (CT) on retinal cells under hypoxic conditions are not well understood. The aim of the present study was to explore how CT exerted its protective effects on retinal pigment epithelium (RPE) cells under hypoxic conditions induced by cobalt chloride (CoCl₂). The effects of CT were investigated using a Cell Counting Kit-8 assay, Annexin V-FITC/PI staining, reverse transcription-quantitative PCR and western blotting in ARPE-19 cells. CT (10 and 20 µM) reduced the CoCl₂-induced increase in vascular endothelial growth factor expression and hypoxia-inducible transcription factor-1α expression in ARPE-19 cells. Additionally, CT alleviated hypoxia-induced apoptosis by regulating Bcl-2 and Bax protein expression. CT treatment also reduced the increase in the mRNA levels of IL-6, IL-1β and TNF-α induced by CoCl₂. In summary, CT may protect RPE cells against apoptosis and inflammation in CoCl₂-induced hypoxia, and these results warrant further in vivo study into its value as a drug for treating hypoxic eye diseases.

Evaluation of retinal inflammatory biomarkers after intravitreal steroid implant and Ranibizumab injection in diabetic macular edema

PURPOSE

To compare the efficacy of intravitreal (IV) ranibizumab (IVR) injection with IV dexamethasone implant (IVDEX) in treatment naive diabetic macular edema (DME) patients with inflammatory component.

MATERIALS AND METHODS

Treatment naive DME eyes with subfoveal neurosensorial detachment (SND) and hyperreflective spots (HRS) were treated either three loading doses of IVR (18 eyes) or one dose of IVDEX (19 eyes). Central macular thickness (CMT), height of SND, the number of HRSs scattered on the individual retinal layers and photoreceptor integrity were assessed using spectral domain- optical coherence tomography scans over 3-months follow-up.

RESULTS

The mean change in best-corrected visual acuity (BCVA) was -0.11 ± 0.08 logMAR in IVDEX group and -0.04 ± 0.06 logMAR in IVR group at 1-month (p = 0.011). IVDEX group showed statistically significant more increase in BCVA compared to those receiving IVR injections at 2-months (p = 0.004) and 3-months (p = 0.017) visits. Compared to baseline, the number of total HRSs and the number of HRSs at each individual inner retinal layer significantly decreased in both groups at all follow-up visits. However, IVDEX group showed more decrease in the total number of HRSs at 2- and 3-months (p < 0.001 at 2-months, and p = 0.006 at 3-months) and in the mean number of HRSs located at inner nuclear layer-outer plexiform layer level (p = 0.016 at 1-month, p < 0.001 at 2-months, and p < 0.001 at 3-months). After treatment, the number of HRSs on the outer nuclear layer showed some non-significant increase in both groups.

CONCLUSION

HRSs tended to migrate from inner retina to the outer retina in DME eyes by treatment. Dexamethasone seemed to be more effective option in such cases with inflammatory component.

Involvements of choroidal vascular structures with local treatments in patients with diabetic macular edema

PURPOSE

To examine changes of the choroidal morphology in patients with diabetic macular edema (DME) before and after local treatments.

METHODS

This study was on 20 eyes with DME, observed for more than 24 months. All patients underwent laser photocoagulation (Laser), sub-tenon triamcinolone acetonide injection (TA), or intravitreal aflibercept injection (IVA). Central macular and choroidal thicknesses (CMT/CCT), and choroidal vascular structures consisting of the total choroidal area (TCA), luminal area (LA), and stromal area (SA) were measured by a binarization method. The ratios of LA in TCA were eventually determined as the L/C ratio in each case.

RESULTS

The L/C ratio significantly decreased for 24 months in patients with DME (p = 0.01), whereas no significant differences were noted in other parameters including TCA, LA, SA, or CCT. Among patients treated with Laser ± TA ± IVA, a significant correlation was found between a high L/C ratio at pretreatment and a lower cumulative number of injections (1-2 times/24 months) (p = 0.04). The L/C ratio in pretreatment showed a significantly inverse correlation with CMT (-0.60, p = 0.02) and subsequent BCVA (logMAR) (-0.59, p = 0.03).

CONCLUSION

This study highlighted that the L/C ratio in pretreatment might predict a change of the visual acuity in DME.

Human umbilical cord mesenchymal stem cells in type 2 diabetes mellitus: the emerging therapeutic approach

The umbilical cord has been proved to be an easy-access, reliable, and useful source of mesenchymal stem cells (MSC) for clinical applications due to its primitive, immunomodulatory, non-immunogenic, secretory and paracrine, migratory, proliferative, and multipotent properties. This set of characteristics has recently attracted great research interest in the fields of nanotechnology and regenerative medicine and cellular therapy. Accumulating evidence supports a pronounced therapeutic potential of MSC in many different pathologies, from hematology to immunology, wound-healing, tissue regeneration, and oncology. Diabetes mellitus, branded the epidemic of the century, is considered a chronic metabolic disorder, representing a major burden for health system sustainability and an important public health challenge to modern societies. The available treatments for type 2 diabetes mellitus (T2DM) still rely mainly on combinations of oral antidiabetic agents with lifestyle and nutritional adjustments. Despite the continuous development of novel and better hypoglycemic drugs, their efficacy is limited in the installment and progression of silent T2DM complications. T2DM comorbidities and mortality rates still make it a serious, common, costly, and long-term manageable disease. Recently, experimental models, preclinical observations, and clinical studies have provided some insights and preliminary promising results using umbilical cord MSCs to treat and manage diabetes. This review focuses on the latest research and applications of human-derived umbilical cord MSC in the treatment and management of T2DM, exploring and systematizing the key effects of both umbilical cord MSC and its factor-rich secretome accordingly with the major complications associated to T2DM.

Significance of monitoring vascular endothelial growth factor, monocyte chemoattractant protein-1 and Interleukin-8 in diabetic macular edema towards early identification of nonresponders to ranibizumab therapy

Purpose:

Identification of nonresponders prior to anti-vascular endothelial growth factor (anti-VEGF) therapy would help in the judicious clinical management of diabetic macular edema (DME) patients. Thus, a systematic study was initiated to identify nonresponding DME patient population undergoing ranibizumab treatment to figure out additional inflammatory components that may contribute to their nonresponsiveness to anti-VEGF therapy.

Methods:

A total of 40 patients recruited to this investigator-initiated trial received intravitreal ranibizumab monthly for 3 months. The fourth- and fifth-month injections were according to PRN protocol and the sixth-month injection was mandatory. Best-corrected visual acuity (BCVA), central macular thickness (CMT), and VEGF in aqueous humor were measured for all the patients. Patients were grouped into responders/nonresponders on the formulated criteria and the levels of key pro-inflammatory cytokines were also measured between the two groups at baseline, 2 month and 5 months using cytometric bead array (CBA).

Results:

Eleven patients were categorized (29.72%) as responders and 10 patients (27.02%) as nonresponders. Nonresponders showed poorer BCVA (P = 0.024, 0.045, and 0.048 for 4, 5, and 6 months) and higher CMT (P = 0.021, 0.0008 and <0.0001 for baseline, 1, 2, 3, 4, 5, and 6 months) compared to responders. The cytokines IL-8, MCP-1 were significantly up regulated (P = 0.0048 and 0.029 for MCP-1 and IL-8) in nonresponders.

Conclusion:

Elevated MCP-1 and IL-8 levels found in the nonresponders could be used as a prognostic marker to identify these groups of patients and can help in developing alternative treatment options along with anti-VEGF therapy.

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.

Comparing vision and macular thickness in neovascular age-related macular degeneration, diabetic macular oedema and retinal vein occlusion patients treated with intravitreal antivascular endothelial growth factor injections in clinical practice

Objective

To compare the visual outcomes of intravitreal antivascular endothelial growth factor (anti-VEGF) injections in neovascular age-related macular degeneration (nAMD), diabetic macular oedema (DMO) and retinal vein occlusion (RVO) in a real-world setting.

Methods and analysis

Retrospective analysis of data from the Tasmanian Ophthalmic Biobank database. The median change in best-corrected visual acuity (BCVA) between baseline and 12 months post initiating intravitreal anti-VEGF treatment were compared between the three diseases. Final BCVA, central macular thickness (CMT), cumulative number of injections and overall predictors of change in BCVA and CMT were also determined.

Results

At 12 months, change in BCVA was significantly different between nAMD, DMO and RVO cohorts (p=0.032), with lower median change for DMO (2 letters, range −5 to 20) than for RVO (11 letters, range −20 to 35). Likewise, CMT change was significantly different between the three cohorts (p=0.022), with a smaller reduction in CMT in DMO (−54 µm, range −482 to 50) than RVO patients (−137 µm, range −478 to 43; p=0.033). Total number of injections received (p=0.028) and final BCVA score (p=0.024) were also significantly different between the groups. Baseline BCVA was a negative predictor (p=0.042) and baseline CMT a positive predictor (p<0.001) of outcome. After adjusting for baseline BCVA and CMT, diagnosis of nAMD or RVO was a predictor of visual improvement compared with the DMO.

Conclusions

At the end of 12 months, nAMD and RVO cohorts had the greatest improvement in BCVA, however the final BCVA for DMO was significantly better than for nAMD.

Role of Oral Antioxidant Supplementation in the Current Management of Diabetic Retinopathy

Oxidative stress has been postulated as an underlying pathophysiologic mechanism of diabetic retinopathy (DR), the main cause of avoidable blindness in working-aged people. This review addressed the current daily clinical practice of DR and the role of antioxidants in this practice. A systematic review of the studies on antioxidant supplementation in DR patients was presented. Fifteen studies accomplished the inclusion criteria. The analysis of these studies concluded that antioxidant supplementation has a IIB level of recommendation in adult Type 1 and Type 2 diabetes mellitus subjects without retinopathy or mild-to-moderate nonproliferative DR without diabetic macular oedema as a complementary therapy together with standard medical care.

Involvement of Cytokines in the Pathogenesis of Diabetic Macular Edema

Diabetic macular edema (DME) is a critical complication of diabetic retinopathy, a condition that arises from the breakdown of the blood–retinal barrier and the consequent increase in vascular permeability. Over the years, attempts have been made to treat DME by various approaches, including laser photocoagulation, steroid triamcinolone acetonide, and vitrectomy. However, treatment was unsatisfactory until research identified vascular endothelial growth factor (VEGF) as a factor in the pathogenesis of DME. Intraocular anti-VEGF agents show good efficacy in DME. Nevertheless, in some patients the condition recurs or becomes resistant to treatment, suggesting that other factors may be involved. Because inflammation and retinal hypoxia are seen in DME, research has examined the potential role of cytokines and other inflammatory mediators. In this review, we provide an overview of this research and describe feedback mechanisms that may represent a target for novel treatments.

The innate immune system in diabetic retinopathy

The prevalence of diabetes has been rising steadily in the past half-century, along with the burden of its associated complications, including diabetic retinopathy (DR). DR is currently the most common cause of vision loss in working-age adults in the United States. Historically, DR has been diagnosed and classified clinically based on what is visible by fundoscopy; that is vasculature alterations. However, recent technological advances have confirmed pathology of the neuroretina prior to any detectable vascular changes. These, coupled with molecular studies, and the positive impact of anti-inflammatory therapeutics in DR patients have highlighted the central involvement of the innate immune system. Reminiscent of the systemic impact of diabetes, immune dysregulation has become increasingly identified as a key element of the pathophysiology of DR by interfering with normal homeostatic systems. This review uses the growing body of literature across various model systems to demonstrate the clear involvement of all three pillars of the immune system: immune-competent cells, mediators, and the complement system. It also demonstrates how the relative contribution of each of these requires more extensive analysis, including in human tissues over the continuum of disease progression. Finally, although this review demonstrates how the complex interactions of the immune system pose many more questions than answers, the intimately connected nature of the three pillars of the immune system may also point to possible new targets to reverse or even halt reverse retinopathy.

Intravitreal ranibizumab reduced ocular blood flow and aqueous cytokine levels and improved retinal morphology in patients with diabetic macular edema

We investigated the relationship between aqueous cytokine levels, changes in ocular blood flow, and morphological and functional improvements after intravitreal ranibizumab injection (IRI) in treatment-naïve eyes with center-involving diabetic macular edema (DME). Thirty-three eligible patients with DME (33 eyes) were recruited. At the first IRI, we collected a sample of aqueous humor from each eye and measured levels of the cytokines/chemokines. Mean blur rate (MBR) was used to evaluate retinal and choroidal flow by laser speckle flowgraphy at the time of the first IRI and 1 month later. One month after IRI, both retinal and choroidal MBR had significantly decreased from baseline. The reduction ratio of the retinal MBR was significantly correlated with aqueous levels of monocyte chemotactic protein (MCP)-1 and interleukin-8, and with reduction of central macular thickness, but not with improvement of best corrected visual acuity. The reduction ratio of choroidal MBR showed no statistical correlation with any cytokine levels or changes in clinical parameters. We conclude that IRI reduces both retinal and choroidal blood flow in treatment-naïve DME. Reduction of retinal blood flow correlated with regression of morphological pathology, which is regulated by the initial aqueous levels of some cytokines.

PPARα Agonist Oral Therapy in Diabetic Retinopathy

Diabetic retinopathy (DR) is an eye condition that develops after chronically poorly-managed diabetes, and is presently the main cause for blindness on a global scale. Current treatments for DR such as laser photocoagulation, topical injection of corticosteroids, intravitreal injection of anti-vascular endothelial growth factor (VEGF) agents and vitreoretinal surgery are only applicable at the late stages of DR and there are possibilities of significant adverse effects. Moreover, the forms of treatment available for DR are highly invasive to the eyes. Safer and more effective pharmacological treatments are required for DR treatment, in particular at an early stage. In this review, we cover recently investigated promising oral pharmacotherapies, the methods of which are safer, easier to use, patient-friendly and pain-free, in clinical studies. We especially focus on peroxisome proliferator-activator receptor alpha (PPARα) agonists in which experimental evidence suggests PPARα activation may be closely related to the attenuation of vascular damages, including lipid-induced toxicity, inflammation, an excess of free radical generation, endothelial dysfunction and angiogenesis. Furthermore, oral administration of selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα) agonists may induce hepatic fibroblast growth factor 21 expression, indirectly resulting in retinal protection in animal studies. Our review will enable more comprehensive approaches for understanding protective roles of PPARα for the prevention of DR development.