Current concepts of pharmacotherapy of diabetic macular edema

Effectiveness and tolerability of the fluocinolone acetonide implant in patients with diabetic macular edema in the UAE: 24 and 36-month outcomes

INTRODUCTION

The effectiveness and safety of the fluocinolone acetonide (FAc) implant was evaluated at Month 24 and, in some sustained for up to 36 months, in patients with diabetic macular edema (DME) and a pseudophakic lens treated in the UAE following prior anti-vascular endothelial growth factor and dexamethasone (DEX) implant.

METHODS

This was a retrospective, observational audit study conducted between September 2017-September 2020 in which 22 patients were treated with the FAc implant and outcomes monitored for up to 36 months. Effectiveness outcomes were: best-corrected visual acuity (BVCA) and central macular thickness (CMT). Safety was assessed by monitoring intraocular pressure (IOP). All outcomes were measured at Months 1, 3, 6, 12, 24, and 36.

RESULTS

Significant improvements in mean BCVA were observed versus baseline from Month 1, which were maintained up to Month 24 (P < 0.0001 versus baseline). In all five patients completing 36 months follow-up, the improvements in BVCA were maintained through to Month 36 P < 0.005 versus baseline. Similarly, mean CMT improved versus baseline at Month 1 through to Month 24 (P < 0.0001 versus baseline), with significant improvements also noted in the 5 patients completing 36 months follow-up (P < 0.005 versus baseline). An IOP rise to 32 mmHg was observed in one eye, but returned to normal values at next measure. Five eyes required IOP lowering drops and one required IOP-lowering surgical intervention.

CONCLUSION

The FAc intravitreal implant is effective for 24 months, and sustained for 36 months, in a UAE population previously treated with a DEX implant, with tolerability profile in-line with previous reports.

The Change of Aqueous Humor Cytokine Levels after Anti-VEGF in Diabetic Macular Edema: A Systematic Review and Meta-Analysis

Background

Diabetic macular edema (DME) is a vision-threatening complication that severely impairs vision, and VEGF has a certain improvement effect on it as a growth factor.

Objective

To assess the alterations of different aqueous humor cytokine concentrations after intravitreal antivascular endothelial growth factor (VEGF) treatment for diabetic macular edema (DME).

Methods

We searched PubMed, EMBASE, and the Cochrane Library from inception up to May 2022 for studies evaluating the alterations of different aqueous humor cytokine concentrations after intravitreal anti-VEGF treatment for diabetic macular edema. The estimates from eligible studies were meta-analyzed by the Hartung-Knapp/Sidik-Jonkman random-effects method. Egger's regression test was used to determine the publications' bias. A 95% confidence interval was calculated across studies. The analysis was performed using STATA™ Version 15 software.

Results

Nine eligible studies involving a total of 209 eyes for our systematic review were identified through our search strategy. The mean differences in 1-month and 2-month changes of VEGF were 110.681 pg/ml (P < 0.001) and 283.474 pg/ml (P=0.003), respectively. The mean difference in 2-month changes of interleukin 6 (IL-6) was -24.784 pg/ml (P=0.037). The mean difference in 3-month changes of central macular thickness was 130.372 μm (P < 0.001).

Conclusions

Intravitreal injection of anti-VEGF exerts a protective effect on macular edema secondary to diabetic retinopathy by affecting various cytokine concentrations, especially reducing aqueous VEGF concentrations and interleukin 6 in patients with DME.

Current and Novel Therapeutic Approaches for Treatment of Diabetic Macular Edema

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

Disentangling the association between retinal non-perfusion and anti-VEGF agents in diabetic retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus (DM) and the leading cause of blindness in patients with DM. In the pathogenesis of DR, chronic hyperglycemia leads to biochemical and structural alterations in retinal blood vessels' wall, resulting in hyperpermeability and non-perfusion. Since vascular endothelial growth factor (VEGF) has been found to play a significant role in the pathogenesis of DR, this review sheds light on the effect of intravitreal anti-VEGF agents on retinal non-perfusion in patients with DR. Based on the existing literature, anti-VEGF agents have been shown to improve DR severity, although they cannot reverse retinal ischemia. The results of the published studies are controversial and differ based on the location of retinal non-perfusion, as well as the imaging modality used to assess retinal non-perfusion. In cases of macular non-perfusion, most of studies showed no change in both fundus fluorescein angiography (FFA) and optical coherence tomography (OCTA) in patients with DR treated with intravitreal anti-VEGF agents, while few studies reported worsening of non-perfusion with enlargement of foveal avascular zone (FAZ). Regarding peripheral ischemia, studies using wide-field-FFA demonstrated an improvement or stability in non-perfusion areas after anti-VEGF treatment. However, the use of wide-field-OCTA revealed no signs of re-perfusion of retinal vessels post anti-VEGF treatment. Further prospective studies with long follow-up and large sample size are still needed to draw solid conclusions.

Treatment of Macular Edema in Vascular Retinal Diseases: A 2021 Update

Macular edema (ME) is associated with various conditions; however, the main causes of ME are retinal vein occlusion (RVO) and diabetes. Laser photocoagulation, formerly the gold standard for the treatment of ME, has been replaced by anti-vascular endothelial growth factor (anti-VEGF) intravitreal injections. Despite its efficiency, this treatment requires frequent injections to preserve the outcomes of anti-VEGF therapy, and as many patients do not sufficiently respond to the treatment, ME is typically a chronic condition that can lead to permanent visual impairment. Generalized recommendations for the treatment of ME are lacking, which highlights the importance of reviewing treatment approaches, including recent anti-VEGFs, intravitreal steroid implants, and subthreshold micropulse lasers. We reviewed relevant studies, emphasizing the articles published between 2019 and 2021 and using the following keywords: macular edema, diabetic macular edema, retinal vein occlusion, laser photocoagulation, anti-VEGF, and intravitreal injections. Our results revealed that a combination of different treatment methods may be beneficial in resistant cases. Additionally, artificial intelligence (AI) is likely to help select the best treatment option for patients in the near future.

Efficacy of topical dorzolamide 2% in diabetic cystoid macular edema

AIM

To study the effect of topical dorzolamide 2% on macular thickness reduction in diabetic cystoid macular edema (CME).

METHODS

This was a prospective, non-randomized, open study including eyes with diabetic macular edema (DME). All eyes received topical dorzolamide 2% three times daily for one month. Changes in best-corrected visual acuity (BCVA), and central macular thickness (CMT) by optical coherence tomography) were evaluated at 1wk, 1, and 3mo post-treatment.

RESULTS

Ninety-three eyes (84 patients) were included. Mean±SD (logMAR) BCVA improved significantly from 1.08±0.26 pretreatment to 0.66±0.24 at 1mo and 0.87±0.26 at 3mo post-treatment (P<0.001 both). The mean±SD CMT was significantly reduced from 535.27±97.4 µm at baseline to 357.43±125.8 µm at 1mo and 376.23±114.5 µm at 3mo post-treatment (P<0.001 both). No significant ocular or systemic side effects were recorded.

CONCLUSION

Topical dorzolamide 2% results in significant improvement of mean BCVA and reduction of mean CMT at 3mo post-treatment. It can be used as an effective, affordable, and safe therapy for treatment of non-refractory diabetic CME.

Triamcinolone acetonide modulates TGF‑β2‑induced angiogenic and tissue‑remodeling effects in cultured human retinal pigment epithelial cells

Transforming growth factor-β2 (TGF-β2) has been implicated in the pathogenesis of proliferative vitreoretinopathy (PVR) and proliferative diabetic retinopathy (PDR), due to its ability to stimulate the overproduction of pro-angiogenic factors, such as vascular endothelial growth factor (VEGF), and remodeling of the extracellular matrix (ECM). Although intravitreal triamcinolone acetonide (TA) is clinically useful in the treatment of PVR and PDR, its molecular mechanism has yet to be fully elucidated. The present study investigated whether TA treatment altered TGF-β2-driven biological effects on the behavior of cultured human retinal pigment epithelial (RPE) cells, in order to determine which signaling pathway may be essential for the pharmacological action of TA. The R-50 human RPE cell line was treated with TA in the presence of TGF-β2, followed by analyses of cell viability and contraction using cell viability and collagen gel contraction assays. VEGF mRNA expression and protein production were measured using reverse transcription-quantitative PCR and ELISA, respectively. The phosphorylation status of signaling mediators and the protein expression of type I collagen (COL1A1), α-smooth muscle actin (α-SMA), and ECM-remodeling enzymes, including MMP-2 and MMP-9, were analyzed using western blotting. The gelatinolytic activity of MMPs was detected using gelatin zymography. TA treatment exhibited no prominent cytotoxicity but markedly antagonized TGF-β2-induced cytostatic effects on RPE cell viability and TGF-β2-enhanced contractility in collagen gels. In the context of TGF-β2-related signaling, TA significantly attenuated TGF-β2-elicited Smad2, extracellular-regulated kinase (ERK)1/2 and p38 mitogen-activated protein kinase (MAPK) phosphorylation. Moreover, TA markedly mitigated TGF-β2-induced VEGF upregulation through ablation of p38 signaling activity. TA also partially attenuated TGF-β2-elicted expression of COL1A1, α-SMA, MMP-2, and MMP-9, but only suppressed TGF-β2-induced MMP-9 gelatinolytic activity. Mechanistically, the MEK/ERK signaling pathway may have a critical role in the TGF-β2-induced upregulation of COL1A1, α-SMA and MMP-9. In conclusion, TA may be considered a useful therapeutic agent for treating TGF-β2-associated intraocular angiogenesis and tissue remodeling, the underlying mechanism of which may involve the ERK and p38 MAPK signaling pathways.

Challenges in Diabetic Macular Edema Management: An Expert Consensus Report

Purpose

This paper aimed to present daily-practice recommendations for the management of diabetic macular edema (DME) patients based on available scientific evidence and the clinical experience of the consensus panel.

Methods

A group of Spanish retina experts agreed to discuss different aspects related with the clinical management of DME patients.

Results

Panel was mainly focused on therapeutic objectives in DME management; definition terms; and role of biomarkers as prognostic and predictive factors to intravitreal treatment response. The panel recommends to start DME treatment as soon as possible in those eyes with a visual acuity less than 20/25 (always according to the retina unit capacity). Naïve patient was defined, in a strict manner, as a patient who, up to that moment, had never received any treatment. A refractory DME patient may be defined as the one who did not achieve a complete resolution of the disease, regardless of the treatment administered. Different optical coherence tomography biomarkers, such as disorganization of the retinal inner layers, hyperreflective dots, and cysts, have been identified as prognostic factors.

Conclusion

This document has sought to lay down a set of recommendations and to identify key issues that may be useful for the daily management of DME patients.

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

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

Effect of Dexamethasone Intravitreal Implant on Visual Acuity and Foveal Photoreceptor Integrity in Macular Edema Secondary to Retinal Vascular Disease

PURPOSE

The aim of this study was to evaluate the effect of the dexamethasone intravitreal (DEX) implant on the external limiting membrane (ELM) and ellipsoid zone (EZ) integrity in treatment-naïve patients with macular edema (ME) secondary to retinal vascular disease (RVD).

METHODS

This is a retrospective study conducted on patients with ME secondary to RVD, who underwent a DEX implant.

RESULTS

One-hundred eyes were included. Mean age was 70.3 ± 11.1 years. Mean ELM integrity significantly improved from 1,575.9 ± 285.9 μm at baseline to 1,711.7 ± 244.0 μm at month 3 (p < 0.0001). Similarly, there was a significant improvement in EZ integrity from baseline to month 3 (1,531.5 ± 317.1 vs. 1,694.3 ± 252.8 μm, respectively, p < 0.0001). At month 3, mean visual acuity (VA) gain was 9.9 ± 14.1 letters (p < 0.0001). Mean central retinal thickness (CRT) significantly decreased by -193.2 ± 185.7 μm from baseline to month 3 (p < 0.0001). Mean changes in VA and CRT were significantly correlated with baseline ELM integrity (p = 0.0065 and p = 0.0046, respectively) and EZ integrity (p = 0.0300 and p = 0.0035, respectively). At month 3, the proportion of eyes which had an intact ELM (mean difference 16.0%, 95% CI 5.4-26.4%, p = 0.0033) and EZ (mean difference 12.0%, 95% CI 1.8-22.1%, p = 0.0210) was significantly higher than at baseline.

CONCLUSIONS

DEX implant was able to significantly improve ELM and EZ integrity in naïve patients with ME.

Review of clinical studies and recommendation for a therapeutic flow chart for diabetic macular edema

Diabetic macular edema (DME), characterized by exudative fluid accumulation in the macula, is the most common form of sight-threatening retinopathy in patients with diabetes. The management of DME has changed considerably in recent years, especially following the development of intravitreal anti-vascular endothelial growth factor therapy which has emerged as a first-line therapy for center-involved DME. Laser treatment, intravitreal steroid therapy, and vitrectomy are also important treatment options for DME. We believe that it is important to choose the most appropriate treatment option for DME based on the clinical evidences, in addition to the careful consideration of individual patients' general or ocular condition, DME characteristics, patients' motivation, and compliance to the treatment in real-world clinical practice. In this review, we have summarized important clinical evidences for the main treatments for DME, presented an expert review for these evidences, and proposed a recommended therapeutic flow chart for DME. We hope that our review of the clinical evidences and the recommended therapeutic flow chart for DME will contribute to better treatment outcome for DME.

Diabetic Retinopathy: Mitochondria Caught in a Muddle of Homocysteine

Diabetic retinopathy is one of the most feared complications of diabetes. In addition to the severity of hyperglycemia, systemic factors also play an important role in its development. Another risk factor in the development of diabetic retinopathy is elevated levels of homocysteine, a non-protein amino acid, and hyperglycemia and homocysteine are shown to produce synergistic detrimental effects on the vasculature. Hyperhomocysteinemia is associated with increased oxidative stress, and in the pathogenesis of diabetic retinopathy, oxidative stress-mitochondrial dysfunction precedes the development of histopathology characteristic of diabetic retinopathy. Furthermore, homocysteine biosynthesis from methionine forms S-adenosyl methionine (SAM), and SAM is a co-substrate of DNA methylation. In diabetes, DNA methylation machinery is activated, and mitochondrial DNA (mtDNA) and several genes associated with mitochondrial homeostasis undergo epigenetic modifications. Consequently, high homocysteine, by further affecting methylation of mtDNA and that of genes associated with mtDNA damage and biogenesis, does not give any break to the already damaged mitochondria, and the vicious cycle of free radicals continues. Thus, supplementation of sensible glycemic control with therapies targeting hyperhomocysteinemia could be valuable for diabetic patients to prevent/slow down the development of this sight-threatening disease.

Autofluorescence indexes as biomarkers for antiangiogenic loading dose outcome in diabetic macular edema

Purpose:

To evaluate the combination of fundus autofluorescence results with several clinical and structural variables into mathematical indexes to enhance their ability to predict visual and anatomical changes after the antivascular endothelial growth factor loading dose.

Methods:

Patients with diabetic macular edema were enrolled. Each patient had a comprehensive ophthalmological examination, contrast sensitivity, optical coherence tomography, and fundus autofluorescence assessment. All patients received three monthly doses of ziv-aflibercept and were followed each month for response assessment. Autofluorescence was classified according to its level into five grades. The grades were combined with other variables (best-corrected visual acuity, contrast sensitivity, central macular thickness, macular cube volume, and macular cube average thickness) into normalized indexes. Statistical assessment was done using a Spearman’s rank correlation coefficient, linear regression, and interobserver-agreement analysis.

Results:

There was a strong correlation between the fundus autofluorescence/baseline best-corrected visual acuity index and the fundus autofluorescence/contrast-sensitivity index at baseline with the best-corrected visual acuity after the third dose of ziv-aflibercept (r_s = −0.78, p = .000 and r_s = −0.68, p = .0009 respectively). The fundus autofluorescence/baseline best-corrected visual acuity index and the fundus autofluorescence/contrast-sensitivity index, both at baseline had a mild correlation with the macular volume at 1 month of follow-up (r_s = 0.56, p = .008 and (r_s = 0.64, p = .002, respectively).

Conclusion:

This study suggests that it is possible to combine fundus autofluorescence results with functional and structural variables into normalized indexes that could potentially predict outcomes after antivascular endothelial growth factor loading dose in patients with diabetic macular edema.

Evaluation of the efficacy of Conbercept in the treatment of diabetic macular edema based on OCTA

BACKGROUND

Diabetic macular edema (DME) can cause severe vision impairments for patients with diabetes. Recently, Conbercept has shown efficacy on DME with 3-monthly loading dose injection and pro re nata (PRN, 3+PRN) thereafter in retrospectivetrials. Furthermore, there are some other approaches have been recommended such as 2mg bimonthly (2q8) after 5 initial doses, or Conbercept 0.5mg treat-and-extend, however, some patients still have recurrence of the disease after treatment. Therefore, in order to identify more efficacy and safety approach on Conbercept inpatients with DME, a randomized controlled trial will be performed with 6-monthly loading dose injection and PRN (6+PRN) compared with 3+PRN treatments.

METHODS

This study is a multicenter, randomized control trial of Conbecept treating DME in China. Patients with type 2 diabetes suffered from DEM who already planned to receive Conbercept treatment will be recruited. All subjects will be randomized divided into either a study agent treatment group (6+PRN) or a control group (3+PRN), and observes the subjects for 48 weeks after initiation of treatment.

RESULTS

This study will provide a new powerful evidence of the efficacy and safety of Conbecept treating DME.

DISCUSSION

This RTC study will determine whether multiple treatments of Conbercept provide better effectiveness in patients with DME.

TRIAL REGISTRATION NUMBER

ChiCTR2000032728.