Therapeutic Options in Refractory Diabetic Macular Oedema

ANTERIOR SUBTENON TRIAMCINOLONE INJECTION FOR REFRACTORY MACULAR EDEMA: A Retrospective Case Series

PURPOSE

To evaluate the effectiveness of anterior subtenon triamcinolone (AST) injections in the management of refractory macular edema.

METHODS

This is a retrospective case series of consecutive eyes with refractory macular edema treated with AST at a single vitreoretinal surgeon's practice at Toronto Western Hospital, University of Toronto, Canada in 2018 to 2023. Refractory was defined as persistent macular edema with a central subfield thickness of 250 µ m or greater over a 24-week period, receiving at least four intravitreal antivascular endothelial growth factor injections. Vision outcomes and optical coherence tomography features for all eyes were compared for three visits pre-AST treatment and two visits post-AST treatment.

RESULTS

Ninety-three patients (119 eyes); diabetic macular edema (26%), and pseudophakic cystoid macular edema (74%), with a mean follow-up duration of 161 days were included. The presence of subretinal fluid ( P = 0.0013), central subfield macular thickness ( P < 0.0001), cube average thickness ( P = 0.0024), and macular cube volume ( P = 0.0017) significantly improved from pre-AST to post-AST treatment. Visual acuity also significantly improved from pre-AST treatment to post-AST treatment ( P < 0.0001). There was no significant change in the intraocular pressures from pre-AST to post-AST ( P = 0.7920), and no complications were noted throughout the follow-up period.

CONCLUSION

The findings from this study suggest that AST injections show modest improvement in anatomical and functional outcomes and are safe for the treatment and management of refractory macular edema.

Visual and anatomical failure of anti-VEGF therapy for retinal vascular diseases: a survival analysis of real-world data

IMPORTANCE

Predicting undesirable outcomes following anti-VEGF initiation in macular oedema is critical for effective clinical decision-making and optimised care.

OBJECTIVE

To estimate the time to undesirable events in diabetic macular oedema (DMO), central and branch vein occlusions (CRVO and BRVO) after appropriate loading doses with either ranibizumab or aflibercept and identified baseline predictors of negative outcome.

DESIGN, SETTING, PARTICIPANTS

A retrospective cohort study of 3277 patients (N = 2107 in DMO, N = 413 in CRVO and N = 757 in BRVO) collected over a 10-year period, in a large UK tertiary centre. Only one eye was included per patient. Inclusion criteria pre-specified a minimum of two clinic visits with one being at least 6 months post treatment.

MAIN OUTCOME AND MEASURES

The main outcome measure was absence of visual acuity (VA) improvement due to macular oedema failure of anti-VEGF therapy (defined as VA gain <5 ETDRS letters and CST increase of 50 µm or CST > 325 µm) modelled using time-event analyzes of appropriately loaded patients. Secondary outcomes included survival curves by individual condition (DMO, CRVO, BRVO) and factors associated with negative outcomes.

RESULTS

After starting anti-VEGF, there was a 50% chance of undesirable outcomes at 2.3, 5.24 and 6.16 years for DMO, CRVO and BRVO, respectively. Cox proportional hazards modelling identified presenting age, intraretinal (IRF) volume, presence of DMO and VA as predictors of negative outcomes, whilst South East Asian ethnicity conferred an independent protective effect.

CONCLUSION

Real-world data suggest that undesirable events following anti-VEGF injections is likely to in 50% of patients by the third year of treatment in spite of appropriate loading. The definition of undesirable treatment events captured nearly all patients who were escalated to another therapy, but this proportion represented a small percentage of our definition of failed response.

ILUVIEN® in diabetic macular edema that persists or recurs despite treatment: Results from the Retina.pt® RIVER audit

PURPOSE

Persistent diabetic macular edema (DME) remains a problem in clinical practice, with many patients having a suboptimal response to the standard of care (SOC). Evidence supports the long-term efficacy of intravitreal fluocinolone acetonide (FAc) implant (ILUVIEN®) in patients that have responded sub-optimally, although there is still scarce data from real-world Portuguese practices. We aimed to monitor the current SOC in selected Portuguese practices prior to FAc implantation and then assess the long-term effectiveness and safety of the FAc implant.

SETTINGS

The study included patient data from five Portuguese public hospitals.

DESIGN

This was a non-interventional, multicenter audit of data collected from Retina.pt registry from patients with persistent or recurrent DME despite treatment.

METHODS

Outcome measures included changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), and intraocular pressure (IOP). Results were compared at regular times over 36 months.

RESULTS

This study included 222 eyes from 152 patients. A significant decrease in BCVA (P < 0.001) and a significant increase in CMT (P = 0.013) were observed prior to FAc. A significant increase in BCVA was registered at 6 months after FAc implant administration (P < 0.001), which was maintained during follow-up. No relevant changes in IOP were observed. Treatment burden was reduced as a result of treatment with FAc (P < 0.001 for anti-VEGF, corticosteroids, or both treatments) in the full population.

CONCLUSIONS

In Portuguese practice, data showed that pre-FAc implantation, some patients did not respond to SOC treatment and/or they were undertreated. Following FAc implant administration, there were rapid, sustained, long-term visual and anatomical improvements, and a marked reduction in treatment burden.

Metabolic memory and diabetic retinopathy: Legacy of glycemia and possible steps into future

The response of retinal pathology to interventions in diabetic retinopathy (DR) is often independent of the glycated hemoglobin (HbA1c) values at the point of care. This is despite glucose control being one of the strongest risk factors for the development and progression of DR. Previous preclinical and clinical research has indicated metabolic memory, whereby past cumulative glucose exposure may continue to impact DR for a prolonged period. Preclinical studies have evaluated punitive metabolic memory through poor initial control of DM, whereas clinical studies have evaluated protective metabolic memory through good initial control of DM. In this narrative review, we evaluate the preclinical and clinical evidence regarding metabolic memory and discuss how this may form the basis of preventive care for DR by inducing "metabolic amnesia" in people with a history of uncontrolled diabetes in the past. While our review suggested mitochondrial biology may be one such target, research is still far from a possible clinical trial. We discuss the challenges in such research.

Effectiveness of carbonic anhydrase inhibitor loaded nanoparticles in the treatment of diabetic retinopathy

Diabetic Retinopathy (DRP) is a disease consisting of all the structural and functional changes that develop in the retinal layer of the eye due to diabetes. DRP is the most important cause of blindness between the ages of 20-74 in the world, and the most successful standard treatment option in the treatment of DRP is intravitreal injections. To synthesize acetazolamide loaded nanoparticles to be applied intravitreal treatment of DRP and to examine thein vitroefficacy of the nanoparticles. ACZ loaded PHBV nanoparticles (PHBV-ACZ NPs) formulations were prepared. Nanoparticles with a particle size of 253.20 ± 0.55 nm. A DRP model was established and characterized in HRMEC cells. The effect of the nanoparticles on permeability has been investigated and carrier proteins in BRB due to the development of DRP has been investigated. To establish thein vitroDRP model, HRMEC was stimulated with Recombinant human 165 Vascular Endothelial Growth Factor (VEGF), thereby temporarily reducing the expression levels of endothelial junction proteins, increasing the number of intercellular spaces in the monolayers of HRMECs. It was determined that after the cells were exposed to Carbonic anhydrase inhibitors (CAI) loaded nanoparticles, permeability decreased and protein expression increased.

A Randomized Trial Comparing Suprachoroidal and Intravitreal Injection of Triamcinolone Acetonide in Refractory Diabetic Macular Edema due to Epiretinal Membrane

Purpose

To compare the efficacy and safety of suprachoroidal and intravitreal injection of triamcinolone acetonide in pseudophakic patients with refractory diabetic macular edema (DME) due to epiretinal membrane (ERM). Study Design. This study is a randomized clinical trial (RCT). Participants. Twenty-three nonvitrectomized pseudophakic eyes of 23 subjects (9 M and 14 F with mean age: 54.8 years) with refractory DME due to ERM.

Methods

The eyes were randomized to suprachoroidal triamcinolone acetonide injection 4 mg/0.1 ml (SCTA) (n = 13 eyes) or intravitreal triamcinolone acetonide 4 mg/0.1 ml (IVTA) (n = 10 eyes) and were evaluated at baseline and 1 and 3 months after injection to assess outcome measures. Main Outcome Measures. Changes in best-corrected visual acuity (BCVA) (primary outcome), central foveal thickness (CFT) by optical coherence tomography (OCT), and intraocular pressure (IOP) measurement (secondary).

Results

Baseline median BCVA (logMAR) was 1.0 (range 0.8–1.0) in both groups, improved within the SCTA group to 0.8 on the 1^st and 3^rd months, while in the IVTA group, median BCVA changed to 0.8 and 0.9 on the 1^st and 3^rd months, respectively. No significant differences were noted between groups regarding BCVA at baseline (P=0.927), and 1^st (P=0.605) and 3^rd months (P=0.313). Regarding mean CFT, no significant differences were observed at baseline (P=0.353) and at the first month (P=0.214) between both groups, while at the third month, CFT was significantly higher in the IVTA group (385 um) than in the SCTA group (323 um) (P=0.028). Mean IOP was significantly higher in the IVTA group (15 mmHg) on 1^st month than in the SCTA group (12 mmHg) (P=0.011); after 3^rd month, IOP was significantly higher within the IVTA group (18 mmHg) than SCTA (14 mmHg) (P=0.028). No significant difference was noted between both groups at baseline IOP (P=0.435).

Conclusions

Both SCTA and IVTA are effective in reduction of CFT and improvement of patients' visual acuity, but with a higher recurrence rate and rise in IOP after IVTA when compared to SCTA. Both treatments have temporary effects with the possibility of recurrence of DME and the need for retreatment.

IL-17A Damages the Blood-Retinal Barrier through Activating the Janus Kinase 1 Pathway

Blood-retinal barrier (BRB) dysfunction underlies macular oedema in many sight-threatening conditions, including diabetic macular oedema, neovascular age-related macular degeneration and uveoretinitis. Inflammation plays an important role in BRB dysfunction. This study aimed to understand the role of the inflammatory cytokine IL-17A in BRB dysfunction and the mechanism involved. Human retinal pigment epithelial (RPE) cell line ARPE19 and murine brain endothelial line bEnd.3 were cultured on transwell membranes to model the outer BRB and inner BRB, respectively. IL-17A treatment (3 days in bEnd.3 cells and 6 days in ARPE19 cells) disrupted the distribution of claudin-5 in bEnd.3 cells and ZO-1 in ARPE19 cells, reduced the transepithelial/transendothelial electrical resistance (TEER) and increased permeability to FITC-tracers in vitro. Intravitreal (20 ng/1 μL/eye) or intravenous (20 ng/g) injection of recombinant IL-17A induced retinal albumin leakage within 48 h in C57BL/6J mice. Mechanistically, IL-17A induced Janus kinase 1 (JAK1) phosphorylation in bEnd.3 but not ARPE19 cells. Blocking JAK1 with Tofacitinib prevented IL-17A-mediated claudin-5 dysmorphia in bEnd.3 cells and reduced albumin leakage in IL-17A-treated mice. Our results suggest that IL-17A can damage the BRB through the activating the JAK1 signaling pathway, and targeting this pathway may be a novel approach to treat inflammation-induced macular oedema.

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.

Evaluation of Macular Changes in the Long Term after Pars Plana Vitrectomy with Internal Limiting Membrane Peeling for Diabetic Macular Edema

AIM

To evaluate long-term macular changes following pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling for diabetic macular edema (DME).

METHODS

Forty eligible eyes of 37 patients were included in this retrospective study. Best corrected visual acuity (BCVA), central macular thickness (CMT), and 5-mm macular volume (5-MV) were examined preoperatively, postoperatively after 1, 2, 3, 6, 12, and 24 months, and at a final visit. Response to surgical treatment was considered as recurrence, reincrease, or recovery of DME based on macular changes.

RESULTS

Mean follow-up time was 51.1 ± 19.0 months after surgery. Recurrence (n = 5) and reincrease (n = 17) of DME was observed in 22 eyes (55%) and additional treatments were applied. Recovery of DME was observed in 18 eyes (45%). Preoperative and final-visit mean BCVA (logMAR) was 1.08 ± 0.37 and 0.93 ± 0.45, respectively (p = 0.02). Preoperative and final-visit mean CMT was 514.74 ± 155.65 and 281.87 ± 112.58 µm, respectively (p < 0.001). The 5-MV significantly decreased following surgery (from 8.18 ± 1.57 to 6.52 ± 1.39 mm3; p < 0.001). DME was present in 12 eyes (30%) at the final visit.

CONCLUSION

Although PPV with ILM peeling had efficacy in DME management, this effect tended to decrease over time, such that a considerable number of patients required additional treatment.

Optical coherence tomography angiography assessment of 577 nm laser effect on severe non-proliferative diabetic retinopathy with diabetic macular edema

AIM

To quantitatively evaluate the effect of the combined use of 577-nm subthreshold micropulse macular laser (SML) and multi-point mode pan retinal laser photocoagulation (PRP) on severe non-proliferative diabetic retinopathy (NPDR) with central-involved diabetic macular edema (CIDME) using optical coherence tomography angiography (OCTA).

METHODS

In this observational clinical study, 86 eyes of 86 NPDR patients with CIDME who underwent SML and PRP treatment were included. Images were obtained 1d before laser and post-laser (1d, 1wk, 1, 3, and 6mo) using AngioVue software 2.0. Best corrected visual acuity (BCVA, LogMAR), foveal avascular zone area (FAZ), choriocapillary flow area (ChF), parafoveal vessel density (PVD), capillary density inside disc (CDD), peripapillary capillary density (PCD), macular ganglion cell complex thickness (mGCCT), central macular thickness (CMT), and subfoveal choroidal thickness (ChT) were compared between pre- and post-laser treatment.

RESULTS

BCVA remained stable during 6mo post-laser therapy (pre-laser vs 6mo post-laser: 0.53±0.21 vs 0.5±0.15, P>0.05). PVD, ChF, ChT, CMT, and mGCCT significantly increased 1d post-laser therapy [pre-laser vs 1d post-laser: superficial PVD (%), 40.51±3.42 vs 42.43±4.68; deep PVD (%), 42.66±3.67 vs 44.78±4.52; ChF, 1.72±0.21 vs 1.9±0.12 mm²; ChT, 302.45±69.74 vs 319.38±70.93 µm; CMT, 301.65±110.78 vs 320.86±105.62 µm; mGCCT, 105.71±10.72 vs 115.46±9.64 µm; P<0.05]. However, PVD, ChF and ChT decreased to less than baseline level at 6mo post-laser therapy (pre-laser vs 6mo post-laser: superficial PVD (%), 40.51±3.42 vs 36.32±4.19; deep PVD (%), 42.66±3.67 vs 38.76±3.74; ChF, 1.72±0.21 vs 1.62±0.09 mm²; ChT, 302.45±69.74 vs 289.61±67.55 µm; P<0.05), whereas CMT and mGCCT decreased to baseline level at 6mo post-laser therapy (CMT, 301.65±110.78 vs 297.77±90.23 µm; mGCCT, 105.71±10.72 vs 107.05±11.81 µm; P>0.05). Moreover, FAZ continuously increased while CDD and PCD continuously decreased in 6mo after laser therapy. CMT and ChT had a significant positive correlation with ChF and PVD in most post-laser stages.

CONCLUSION

During a 6-month follow-up period after combined use of SML and PRP therapy, BCVA remained stable and there was a decreased trend in macular edema. Blood flow increased at 1d post-laser therapy and reduced at 6mo post-laser therapy.

Prognostic role of optical coherence tomography after switch to dexamethasone in diabetic macular edema

AIMS

To analyze the visual outcome after early switch to dexamethasone (DEX) in eyes with diabetic macular edema previously treated with ranibizumab (RNB), based on structural spectral-domain optical coherence tomography (SD-OCT) features.

METHODS

Retrospective study of data from 28 eyes which underwent a loading dose of three monthly RNB injections and were then shifted to DEX implant injection. SD-OCT analysis was performed before switch to DEX (week 12, 12W) according to the presence of integrity of ellipsoid zone (EZ) and external limiting membrane (ELM), disorganization of retinal inner layers (DRIL), and quantity of hyper-reflective spots (HRS). Best-corrected visual acuity (BCVA) changes at different time points after DEX (month 1, 1M; 4 months, 4M; and 12 months, 12M) were compared among groups.

RESULTS

Significantly better BCVA was achieved at 1M in eyes with intact EZ (84.2 ± 12.3 letters; p  =  0.04), with intact ELM (83.2 ± 11.5 letters; p < 0.01), and with fewer HRS (84.6 ± 12.5 letters; p = 0.03). However, the greatest percentage visual increase was achieved in eyes with disrupted EZ (+ 11.4%; p < 0.01), with disrupted ELM (+ 17.2%; p < 0.01), without DRIL (+ 12.5%; p < 0.01), and with more HRS (+ 14.3%; p = 0.04). After 12 months, a significant BCVA gain was observed only in eyes with intact retinal inner layers (+ 14.2%; p = 0.03).

CONCLUSIONS

Greater percentage BCVA improvement at 1M after switch to DEX was associated with EZ disruption, ELM disruption, intact retinal inner layers, and higher quantity of HRS. A switch to DEX therapy would be useful in patients with these SD-OCT features.

Serum erythropoietin concentration and its correlation with stage of diabetic retinopathy

BACKGROUND

Erythropoietin (EPO) is one of the systemic angiogenic factors, and its role in ocular angiogenesis and in diabetic retinopathy (DR) is not yet fully understood. The latest research data reveal a possible correlation of higher erythropoietin concentrations in the blood and in the eye with the development of more advanced stages of DR. The main aim of this work was to examine the possible influence of serum concentrations of erythropoietin on the development of diabetic retinopathy in patients with diabetes mellitus type 2.

METHODS

The research involved 90 patients examined at the University Eye Clinic of the Clinical Center of Vojvodina, Novi Sad, Serbia. The first group comprised 60 patients with diabetes mellitus lasting for 10 years or more, with diabetic retinopathy. The second, control group consisted of 30 healthy individuals. In the first group of 60 patients with diabetes, 30 of them had non-proliferative diabetic retinopathy (NPDR), and 30 had proliferative diabetic retinopathy (PDR). Laboratory EPO serum levels were determined, and they were correlated to the stage of DR. Concentration of EPO was assessed by ELISA method.

RESULTS

The highest average concentration of EPO in serum (9.95 mIU/ml) was determined in the group of people with diabetes with PDR. The lowest average concentration of EPO in the serum (6.90 mIU/ml) was found in the control group. The average concentration of EPO in serum in the group of patients with diabetes with NPDR was 7.00 mIU/ml. The EPO concentration in serum was elevated in the group of PDR, and it was directly proportional to the level of the clinical stadium of PDR, being significantly higher in the moderate and severe subgroup of PDR comparing to the control healthy subjects, NPDR and mild PDR (p = 0.007).

CONCLUSIONS

Significantly elevated serum concentration of EPO in the advanced stages of DR, and positive correlation between EPO serum concentration and clinical stages of PDR, suggest that erythropoietin represents an important growth factor from blood, which plays a significant role in retinal ischemia and angiogenesis in diabetic retinopathy, especially in the proliferative stage of this disease.

Effect of NADPH oxidase 1 and 4 blockade in activated human retinal endothelial cells

BACKGROUND

Over-production of reactive oxygen species (ROS) and resulting oxidative stress contribute to retinal damage in vascular diseases that include diabetic retinopathy, retinopathy of prematurity and major retinal vessel occlusions. NADPH oxidase (Nox) proteins are professional ROS-generating enzymes, and therapeutic targeting in these diseases has strong appeal. Pharmacological inhibition of Nox4 reduces the severity of experimental retinal vasculopathy. We investigated the potential application of this drug approach in humans.

METHODS

Differential Nox enzyme expression was studied by real-time-quantitative polymerase chain reaction in primary human retinal endothelial cell isolates and a characterized human retinal endothelial cell line. Oxidative stress was triggered chemically in endothelial cells, by treatment with dimethyloxalylglycine (DMOG; 100 μM); Nox4 and vascular endothelial growth factor (VEGFA) transcript were measured; and production of ROS was detected by 2',7'-dichlorofluorescein. DMOG-stimulated endothelial cells were treated with two Nox1/Nox4 inhibitors, GKT136901 and GKT137831; cell growth was monitored by DNA quantification, in addition to VEGFA transcript and ROS production.

RESULTS

Nox4 (isoform Nox4A) was the predominant Nox enzyme expressed by human retinal endothelial cells. Treatment with DMOG significantly increased endothelial cell expression of Nox4 over 72 h, accompanied by ROS production and increased VEGFA expression. Treatment with GKT136901 or GKT137831 significantly reduced DMOG-induced ROS production and VEGFA expression by endothelial cells, and the inhibitory effect of DMOG on cell growth.

CONCLUSIONS

Our findings in experiments on activated human retinal endothelial cells provide translational corroboration of studies in experimental models of retinal vasculopathy and support the therapeutic application of Nox4 inhibition by GKT136901 and GKT137831 in patients with retinal vascular diseases.

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

Diabetic retinopathy and diabetic macular edema comprise a major source of visual disability throughout the developed world. The etiology and pathogenesis of macular edema is intricate and multifactorial, in which the hyperglycemic state in diabetes induces a microangiopathy. Through several inflammatory and vasogenic mediators, including vascular endothelial growth factor (VEGF) upregulation and inflammatory cytokines and chemokines, pathologic changes are induced in the vascular endothelium triggering breakdown of the blood retinal barrier, causing extravasation of fluid into the extracellular space and manifesting clinically as macular edema, resulting in visual loss. The advent of medications targeting the VEGF pathway has led to great clinical improvements compared with the previous standard of care of laser therapy alone, as shown in studies such as RISE, RIDE, VIVID, VISTA, and DRCR. However, analyses have shown that many patients have inadequate response or are nonresponders to anti-VEGF therapy, demonstrating the need for additional therapies to more comprehensively treat this disease. Although corticosteroid treatments and implants have demonstrated some efficacy in adjunctive and supplemental treatment, the need to more adequately treat macular edema remains. Our knowledge of diabetic macular edema continues to grow, leading to new currently available and emerging pharmacotherapies to further enhance our treatment and restore vision in those affected by diabetic macular edema. This review will discuss the pathogenesis of diabetic macular edema and the pharmacologic therapies available for its treatment, including anti-VEGF, steroids, and newer therapies still in development, such as angiopoietin antagonists, Tie2 agonists, kallikrein inhibitors, interleukin inhibitors, and others.