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

Difference of central foveal thickness measurement in patients with macular edema using optical coherence tomography in different display modes

Purpose

To assess the differences in the measurement of central foveal thickness (CFT) in patients with macular edema (ME) between two display modes (1:1 pixel and 1:1 micron) on optical coherence tomography (OCT).

Design

This is a retrospective, cross-sectional study.

Methods

Group A consisted of participants with well-horizontal OCT B-scan images and group B consisted of participants with tilted OCT B-scan. We manually measured the CFT under the two display modes, and the values were compared statistically using the paired t-test. Spearman's test was used to assess the correlations between the OCT image tilting angle (OCT ITA) and the differences in CFT measurement. The area under the curve (AUC) was calculated to define the OCT ITA cutoff for a defined CFT difference.

Results

In group A, the mean CFT in the 1:1 pixel display mode was 420.21 ± 130.61 µm, similar to the mean CFT of 415.27 ± 129.85 µm in the 1:1 micron display mode. In group B, the median CFT in the 1:1 pixel display mode is 409.00 μm (IQR: 171.75 μm) and 368.00 μm (IQR: 149.00 μm) in the 1:1 micron display mode. There were significant differences between the two display modes with the median (IQR) absolute difference and median (IQR) relative difference of 38.00 μm (75.00 μm) and 10.19% (21.91%) (all p = 0.01). The differences in CFT measurement between the two display modes were correlated with the OCT ITA (absolute differences, r = 0.88, p < 0.01; relative differences, r = 0.87, p < 0.01). The AUC for a predefined CFT difference was 0.878 (10 μm), 0.933 (20 μm), 0.938 (30 μm), 0.961 (40 μm), 0.962 (50 μm), and 0.970 (60 μm).

Conclusion

In patients with DM, when the OCT B-scan images were well-horizontal, manual CFT measurements under the two display modes were similar, but when the B-scan images were tilted, the CFT measurements were different under the two display modes, and the differences were correlated to the OCT ITA.

Microinvasive pars plana vitrectomy combined with internal limiting membrane peeling versus anti-VEGF intravitreal injection for treatment-naïve diabetic macular edema (VVV-DME study): study protocol for a randomized controlled trial

BACKGROUND

Diabetic macular edema (DME) is the main cause of vision loss in diabetic patients. Currently, anti-vascular endothelial growth factor (VEGF) intravitreal injection stands as the first-line therapy for DME. However, some patients exhibit insufficient response to anti-VEGF agents and often require multiple injections, imposing psychological and economic burdens. While microinvasive pars plana vitrectomy (PPV) has been shown to be safe and effective in treating refractory DME, scant research has explored its application to treatment-naïve DME. The purpose of this study is to determine whether early PPV combined with internal limiting membrane (ILM) peeling can lessen the therapeutic burden of DME patients, prevent vision loss, and maintain long-term stabilization of diabetic retinopathy.

METHODS

This is a single-center, prospective, parallel-group, non-inferiority randomized controlled trial involving 102 DME participants. Participants will be randomly assigned to either the study group (PPV combined with ILM peeling) or the control group (conbercept intravitreal injection (IVC)) at a 1:1 ratio, with a scheduled follow-up at 12 months post-operation. Comparative analysis of results between the two groups will be conducted at months 1, 3, 6, and 12 after the intervention. The primary outcomes involve evaluating the changes in central subfield thickness (CST) and best corrected visual acuity (BCVA). The secondary outcomes include assessment of optical coherence tomography (OCT) and OCT angiography (OCTA) biomarkers, re-treatment and adverse events rates, diabetic retinopathy (DR) development, cost-effectiveness analysis, and vision-related quality of life (VRQL).

DISCUSSION

Some patients do not respond well to anti-VEGF drugs and repeated intravitreal injections increase the treatment burden for patients. The VVV study aims to explore whether PPV combined with ILM peeling could become an initial treatment option for treatment-naïve DME patients.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05728476. Registered on 15 February 2023.

Characteristics and Treatment Patterns of Patients with Diabetic Macular Edema Non-Responsive to Anti-Vascular Endothelial Growth Factor Treatment in Ontario, Canada

Purpose

To understand the demographics, clinical characteristics, treatment patterns, visual and anatomic responses of patients with diabetic macular edema (DME) initially treated with anti-vascular endothelial growth factor (anti-VEGF) agents in the real-world clinical setting.

Patients and Methods

This retrospective cohort study used electronic health records to identify consecutively presenting patients with DME who received their first documented anti-VEGF injection (index injection) on or after 1 October 2015 and before 30 September 2016 (index period) at 4 clinical sites in Ontario, Canada. Patients receiving anti-VEGF injections in the study eye were followed for ≥18 months. After the first 3 monthly injections, patients were classified as "responder" (≥20% reduction in central retinal thickness [CRT] from index date) or "nonresponder" (<20% reduction in CRT) to anti-VEGF treatment.

Results

At 12 months, change from baseline (CFB) in best visual acuity (BVA) of responders (n = 30) was mean (SD) 12.8 (13.00) letters; CFB in nonresponders (n = 56) was 3.2 (16.3) letters. Sensitivity analyses stratified by initial BVA were supportive. Mean (SD) change in CRT (μm) was -160.4 (111.4) in responders and -62.2 (98.6) in nonresponders. While changes in anti-VEGF therapy were lower in responders versus nonresponders (10.0% vs 23.2%), mean number of injections was similar (8.3 in each cohort).

Conclusion

Despite receiving a substantial number of injections and requiring changes in therapy more frequently, nonresponders showed a lack of clinically meaningful change in BVA and CRT. Nonresponders could be identified after 3 anti-VEGF injections. There remains an unmet need for treatment options in patients with DME who show a nonresponse after 3 months of anti-VEGF treatment.

Association of trabecular meshwork height with steroid-induced ocular hypertension

It is important to identify at-risk patients prior to administering steroid injections to prevent avoidable irreversible blindness inducted by steroid-induced ocular hypertension (SIOH). We aimed to investigate the association of SIOH following intravitreal dexamethasone implantation (OZURDEX) using anterior segment optical coherence tomography (AS-OCT). We conducted a retrospective case control study to assess the association between trabecular meshwork and SIOH. A total of 102 eyes that underwent both AS-OCT and intravitreal dexamethasone implant injection were divided into the post-steroid ocular hypertension and normal intraocular pressure groups. Ocular parameters that can contribute to intraocular pressure were measured using AS-OCT. Univariable logistic regression analysis was used to calculate the odds ratio of the SIOH and significant variables were further analyzed using a multivariable model. Trabecular meshwork (TM) height was significantly shorter in the ocular hypertension group (716.13 ± 80.55 μm) than that in the normal intraocular pressure group (784.27 ± 82.33 μm) (p < 0.001). The receiver operating characteristic curve technique analysis showed that the optimal cut-off of ≥ 802.13 μm for TM height specificity was 96.2%, and TM height with < 646.75 μm had a sensitivity of 94.70%. The odds ratio of the association was 0.990 (p = 0.001). TM height was identified as a newly observed association with SIOH. TM height can be assessed using AS-OCT, with acceptable sensitivity and specificity. Caution must be exercised while injecting steroids in patients with short TM height (especially < 646.75 μm) as it may cause SIOH and irreversible blindness.

Effects of Resveratrol on Vascular Function in Retinal Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) events are involved in the development of various ocular pathologies, e.g., retinal artery or vein occlusion. We tested the hypothesis that resveratrol is protective against I/R injury in the murine retina. Intraocular pressure (IOP) was elevated in anaesthetized mice to 110 mm Hg for 45 min via a micropipette placed in the anterior chamber to induce ocular ischemia. In the fellow eye, which served as control, IOP was kept at a physiological level. One group received resveratrol (30 mg/kg/day p.o. once daily) starting one day before the I/R event, whereas the other group of mice received vehicle solution only. On day eight after the I/R event, mice were sacrificed and retinal wholemounts were prepared and immuno-stained using a Brn3a antibody to quantify retinal ganglion cells. Reactivity of retinal arterioles was measured in retinal vascular preparations using video microscopy. Reactive oxygen species (ROS) and nitrogen species (RNS) were quantified in ocular cryosections by dihydroethidium and anti-3-nitrotyrosine staining, respectively. Moreover, hypoxic, redox and nitric oxide synthase gene expression was quantified in retinal explants by PCR. I/R significantly diminished retinal ganglion cell number in vehicle-treated mice. Conversely, only a negligible reduction in retinal ganglion cell number was observed in resveratrol-treated mice following I/R. Endothelial function and autoregulation were markedly reduced, which was accompanied by increased ROS and RNS in retinal blood vessels of vehicle-exposed mice following I/R, whereas resveratrol preserved vascular endothelial function and autoregulation and blunted ROS and RNS formation. Moreover, resveratrol reduced I/R-induced mRNA expression for the prooxidant enzyme, nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2). Our data provide evidence that resveratrol protects from I/R-induced retinal ganglion cell loss and endothelial dysfunction in the murine retina by reducing nitro-oxidative stress possibly via suppression of NOX2 upregulation.

Development of a Computer System for Automatically Generating a Laser Photocoagulation Plan to Improve the Retinal Coagulation Quality in the Treatment of Diabetic Retinopathy

In this article, the development of a computer system for high-tech medical uses in ophthalmology is proposed. An overview of the main methods and algorithms that formed the basis of the coagulation plan planning system is presented. The system provides the formation of a more effective plan for laser coagulation in comparison with the use of existing coagulation techniques. An analysis of monopulse- and pattern-based laser coagulation techniques in the treatment of diabetic retinopathy has shown that modern treatment methods do not provide the required efficacy of medical laser coagulation procedures, as the laser energy is nonuniformly distributed across the pigment epithelium and may exert an excessive effect on parts of the retina and anatomical elements. The analysis has shown that the efficacy of retinal laser coagulation for the treatment of diabetic retinopathy is determined by the relative position of coagulates and parameters of laser exposure. In the course of the development of the computer system proposed herein, main stages of processing diagnostic data were identified. They are as follows: the allocation of the laser exposure zone, the evaluation of laser pulse parameters that would be safe for the fundus, mapping a coagulation plan in the laser exposure zone, followed by the analysis of the generated plan for predicting the therapeutic effect. In the course of the study, it was found that the developed algorithms for placing coagulates in the area of laser exposure provide a more uniform distribution of laser energy across the pigment epithelium when compared to monopulse- and pattern-based laser coagulation techniques.

Postponed care due to COVID-19 lockdown impact on visual acuity of retinal vein occlusion patients: a large cohort

PURPOSE

To evaluate the impact of postponed care attributed to coronavirus disease (COVID-19) pandemic lockdowns on visual acuity and the number of anti-VEGF injections in patients with retinal vein occlusion (RVO).

METHODS

A multicenter, retrospective study of consecutive RVO patients previously treated with anti-VEGF injections, which compared data from pre- (2019) and during (2020) COVID-19 lockdown period.

RESULTS

A total of 814 RVO patients with a mean age of 72.8 years met the inclusion criteria. Of them, 439 patients were assessed in 2019 and 375 in 2020. There was no significant difference between the COVID-19 and pre-COVID-19 period in terms of baseline and final BCVA (p = 0.7 and 0.9 respectively), but there was a significantly reduced mean number of anti-VEGF injections during the COVID-19 period (5.0 and. 5.9 respectively, p < 0.01), with a constant lower ratio of injections per patient. A noticeable decline was found during March-May (p < 0.01) in 2020. Baseline BCVA (0.69, p < 0.01) and the number of injections (- 0.01, p = 0.01) were predictors of final BCVA.

CONCLUSIONS

In a large cohort of RVO patients, during 2020 lockdowns imposed due to the COVID-19 pandemic, a significant reduction in the annual number of anti-VEGF injections was noted. The postponed care did not result in a significant impact on the final BCVA. Baseline BCVA and the number of annual injections serve as predictors for final BCVA in RVO patients.

Subthreshold Micropulse Laser for Diabetic Macular Edema: A Review

Diabetic macular edema (DME) is one of the main causes of visual impairment in patients of working age. DME occurs in 4% of patients at all stages of diabetic retinopathy. Using a subthreshold micropulse laser is an alternative or adjuvant treatment of DME. Micropulse technology demonstrates a high safety profile by selectively targeting the retinal pigment epithelium. There are no standardized protocols for micropulse treatment, however, a 577 nm laser application over the entire macula using a 200 μm retinal spot, 200 ms pulse duration, 400 mW power, and 5% duty cycle is a cost-effective, noninvasive, and safe therapy in mild and moderate macular edemas with retinal thickness below 400 μm. Micropulse lasers, as an addition to the current gold-standard treatment for DME, i.e., anti-vascular endothelial growth factor (anti-VEGF), stabilize the anatomic and functional retinal parameters 3 months after the procedure and reduce the number of required injections per year. This paper discusses the published literature on the safety and application of subthreshold micropulse lasers in DME and compares them with intravitreal anti-VEGF or steroid therapies and conventional grid laser photocoagulation. Only English peer-reviewed articles reporting research within the years 2010-2022 were included.

Risk Factors and Treatment Strategy for Retinal Vascular Occlusive Diseases

Retinal occlusive diseases are common diseases that can lead to visual impairment. Retinal artery occlusion and retinal vein occlusion are included in the clinical entity, but they have quite different pathophysiologies. Retinal artery occlusion is an emergent eye disorder. Retinal artery occlusion is mainly caused by thromboembolism, which frequently occurs in conjunction with life-threatening stroke and cardiovascular diseases. Therefore, prompt examinations and interventions for systemic vascular diseases are often necessary for these patients. Retinal vein occlusion is characterized by retinal hemorrhage and ischemia, which may impair visual function via several complications such as macular edema, macular ischemia, vitreous hemorrhage, and neovascular glaucoma. Even though anti-vascular endothelial growth factor therapy is the current established first-line of treatment for retinal vein occlusion, several clinical studies have been performed to identify better treatment protocols and new therapeutic options. In this review, we summarize the current findings and advances in knowledge regarding retinal occlusive diseases, particularly focusing on recent studies, in order to provide an update for a better understanding of its pathogenesis.

Review: The Development of Risk Factors and Cytokines in Retinal Vein Occlusion

Retinal vein occlusion (RVO) is the second most prevalent retinal disease. Despite this, the pathogenic mechanisms and risk factors are not entirely clear. In this article, we review recent publications on the classification, pathogenesis, risk factors, ischemic changes, cytokines, and vital complications of RVO. Risk factors and cytokines are important for exploring the mechanisms and new treatment targets. Furthermore, risk factors are interrelated, making RVO mechanisms more complex. Cytokines act as powerful mediators of pathological conditions, such as inflammation, neovascularization, and macular edema. This review aims to summarize the updated knowledge on risk factors, cytokines of RVO and signaling in order to provide valuable insight on managing the disease.

Carbonic anhydrase inhibitors in the management of macular edema: A review of the literature

Background

Macular edema (ME) is a vision-threatening condition that commonly develops as a consequence of ocular diseases, including age-related macular degeneration, retinal vaso-occlusion of the central retinal vein and its branches, diabetic retinopathy, central serous chorioretinopathy, uveitis, retinitis pigmentosa, pseudophakia, ocular trauma, and drug toxicity. The treatment of ME remains challenging, although steroids and vascular endothelial growth factor inhibitors are available. Cost-effective therapy using a noninvasive administration route is required. This study aimed at reviewing the role of carbonic anhydrase inhibitors (CAIs) in the management of ME.

Methods

A literature search was conducted using PubMed/MEDLINE and Google Scholar for studies from January 2000 to March 2022. The following keywords were used in various combinations: "macular edema", "carbonic anhydrase", "carbonic anhydrase inhibitors", "acetazolamide", "dorzolamide", and "brinzolamide".

Results

Articles with high or medium clinical relevance were selected for this review. We found that multiple studies have demonstrated the relevance and efficacy rates of CAIs in the management of ME. Most published studies focused on acetazolamide and dorzolamide, with nearly all studies reporting therapeutic responses.

Conclusions

ME is the leading cause of vision loss and requires noninvasive and cost-effective pharmacotherapy. With progress in the understanding of ME, particularly the role of carbonic anhydrase as a key driver, CAIs are the focus of research. Further optimization of the choice of CAIs and retinal bioavailability, potentially with nanoparticle formulations, is required to enable the effective management of ME. Further research is warranted to address the therapeutic effects of CAIs in different formulations.

KSI-301: an investigational anti-VEGF biopolymer conjugate for retinal diseases

INTRODUCTION

KSI-301 is an intravitreal anti-vascular endothelial growth factor (VEGF) agent in clinical trials for the treatment of neovascular age-related macular degeneration (nAMD), diabetic retinopathy, diabetic macular edema (DME), and retinal vein occlusion (RVO). Its antibody-biopolymer conjugate structure is designed to decrease clearance from the eye and increase the duration of the effect.

AREAS COVERED

This article briefly discusses the impact and mechanisms of nAMD, DME, and RVO and evaluates currently approved anti-VEGF therapies. It progresses to examine a new agent, KSI-301 and the results from numerous clinical trials in these disease areas.

EXPERT OPINION

Despite varied results in the phase 2b/3 study for nAMD, there is potential for KSI-301 to serve as a durable therapy for VEGF-mediated retinal disorders. Ongoing phase 3 trials for nAMD, DME, and RVO will provide additional evidence on its efficacy, duration, and safety profiles.