Optical Coherence Tomography Biomarkers of Inflammation in Diabetic Macular Edema Treated by Fluocinolone Acetonide Intravitreal Drug-Delivery System Implant

Optical coherence tomography for noninvasive monitoring of drug delivery

Optical Coherence Tomography (OCT) has revolutionized various medical imaging and diagnostics fields, offering unprecedented insights into the microstructural compositions of biological tissues. In recent years, OCT applications have been extended to noninvasive drug delivery monitoring, which is a critical aspect of many therapeutic procedures and pharmacokinetic studies. Such an extension is strongly enhanced by the inherent combination with 3D anatomical images provided by OCT. This review presents an overview of the principles of OCT technology, its functional extensions for drug delivery systems, and its advancements in monitoring therapeutic interventions. We discuss its advantages over traditional imaging modalities in terms of spatial resolution, depth penetration, and real-time capabilities. The paper highlights significant studies that have utilized OCT for the visualization and quantification of drug delivery processes, including the diffusion of injectable formulations in ocular tissues and the permeation of topical drugs through the skin. In the review, we focused on the latest OCT applications, including OCT-guided drug injection, topical drug delivery monitoring, application of OCT in inhaled drug delivery systems, and the integration of OCT with other imaging modalities.

Multimodal imaging in diabetic retinopathy and macular edema: An update about biomarkers

Diabetic macular edema (DME), defined as retinal thickening near, or involving the fovea caused by fluid accumulation in the retina, can lead to vision impairment and blindness in patients with diabetes. Current knowledge of retina anatomy and function and DME pathophysiology has taken great advantage of the availability of several techniques for visualizing the retina. Combining these techniques in a multimodal imaging approach to DME is recommended to improve diagnosis and to guide treatment decisions. We review the recent literature about the following retinal imaging technologies: optical coherence tomography (OCT), OCT angiography (OCTA), wide-field and ultrawide-field techniques applied to fundus photography, fluorescein angiography, and OCTA. The emphasis will be on characteristic DME features identified by these imaging technologies and their potential or established role as diagnostic, prognostic, or predictive biomarkers. The role of artificial intelligence in the assessment and interpretation of retina images is also discussed.

Optical coherence tomography-derived texture-based radiomics features identify eyes with intraocular inflammation in the HAWK clinical trial

Background and objective

Intravitreal injection of anti-VEGF agents is the first-line treatment for patients with neovascular-age related macular degeneration (nAMD). One unique serious adverse event that may be associated with these agents is intraocular inflammation (IOI). The main purpose of this analysis was to evaluate the potential presence of texture-based radiomics features characterizing heterogeneity within the vitreous compartment of spectral domain optical coherence tomography (SD-OCT) images that may precede or develop in association with IOI and might serve as OCT biomarkers for IOI.

Methods

This is a post-hoc analysis of a subset of cases (N = 67) involving IOI, endophthalmitis, and/or retinal vascular occlusion in the phase 3 HAWK trial. These were investigator determined diagnoses that were also confirmed by the safety review committee. Intraocular inflammation was any signs of inflammation within the eye, endophthalmitis was inflammation associated with presumed infection, and retinal vascular occlusions consisted of intraocular inflammation with concurrent vascular occlusions/vasculitis. Out of 67 eyes, 34 belonged to the Safety group with an IOI event and 33 were propensity-matched Controls. A total of 481 texture-based radiomics features were extracted from the vitreous compartment of the SD-OCT scans at pre-IOI time point (i.e., much earlier than the actual event). Most discriminating five features, selected by the Wilcoxon Rank Sum feature selection were evaluated using Random Forest (RF) classifier on the training set (S t r , N = 47) to differentiate between the two patient groups. Classifier performance was subsequently validated on the independent test set (S t , N = 20). Additionally, the classifier performance in discriminating the Control and Safety group was also validated onS t at the IOI event timepoint.

Results

The RF classifier yielded area under the Receiver Operating Characteristics curve (AUC) of 0.76 and 0.81 onS t using texture-based radiomics features at pre-IOI and event time-point, respectively.

Conclusions

In this analysis, the presence of a pre-IOI safety signal was detected in the form of textural heterogeneity within the vitreous compartment even prior to the actual event being identified by the investigator. This finding may help the clinicians to assess for underlying posterior inflammation.

Persistent diabetic macular edema: Definition, incidence, biomarkers, and treatment methods

Intravitreal antivascular endothelial growth factor (anti-VEGF) treatment has drastically improved the visual and anatomical outcomes in patients with diabetic macular edema (DME); however, success is not always guaranteed, and a proportion of these eyes demonstrate persistent DME (pDME) despite intensive treatment. While standardized criteria to define these treatment-resistant eyes have not yet been established, many studies refer to eyes with no clinical response or an unsatisfactory partial response as having pDME. A patient is considered to have pDME if the retinal thickness improves less than 10-25% after 6 months of treatment. A range of treatment options have been recommended for eyes with pDME, including switching anti-VEGF agents, using corticosteroids and/or antioxidant drugs in adjunct with anti-VEGF therapy, and vitrectomy. In addition, multimodal imaging of DME eyes may be advantageous in predicting the responsiveness to treatment; this is beneficial when initiating alternative therapies. We explore the literature on persistent DME regarding its defining criteria, incidence, the baseline biological markers that may be useful in anticipating the response to treatment, and the available treatment options.

Factors associated with the response to fluocinolone acetonide 0.19 mg in diabetic macular oedema evaluated as the area-under-the-curve

OBJECTIVES

The area-under-the-curve (AUC) measures the average drug effect over time. We investigated the impact of baseline clinical and optical coherence tomography (OCT) factors on the response to fluocinolone acetonide (FAc) 0.19 mg implant in patients with diabetic macular oedema (DMO) as the AUC over 36 months.

METHODS

Retrospective study of DMO eyes undergoing FAc with follow-up from 12 to 36 months. The AUC of the best-corrected visual acuity (BCVA) and the central macular thickness (CMT) were calculated with the trapezoidal rule. Demographic and clinical data at the time of FAc administration were collected, and associations with BCVA and CMT changes were investigated with linear mixed models.

RESULTS

Eighty-nine eyes of 63 patients were enroled; median follow-up was 26 months. Mean±standard deviation (SD) AUCBCVA and AUCCMT after FAc injection were 0.24 ± 0.17 LogMAR/month and 179.6 ± 54.3 μm/month, respectively. Worse baseline BCVA (β = 0.30 LogMAR/month, p < 0.001), higher AUCCMT after FAc administration (β = 0.08 LogMAR/month, p < 0.001), diagnosis of type 1 diabetes (β = -0.04 LogMAR/month, p = 0.04), and absent ELM/EZ layers (β = 0.06 LogMAR/month, p = 0.01) were associated with worse vision over time (higher AUCBCVA). Eyes with higher CMT at baseline (β = 9.61 μm/month, p < 0.001) and those with tractional DMO (β = 24.7 μm/month, p = 0.01) had worse anatomic outcomes (higher AUCCMT). The need for additional treatments after FAc was also associated with higher AUCCMT (β = 33.9 μm/month, p = 0.001).

CONCLUSION

Baseline better visual acuity, lower macular thickness, and photoreceptors' layers integrity are associated with better functional response to FAc in DMO. Eyes with severe DMO at the time of implant or tractional oedema have worse anatomic response. These findings might guide clinicians in a more informed decisional algorithm in treating DMO.

The Role of Inflammation and Therapeutic Concepts in Diabetic Retinopathy-A Short Review

Diabetic retinopathy (DR) as a microangiopathy is the most common complication in patients with diabetes mellitus (DM) and remains the leading cause of blindness among adult population. DM in its complicated pathomechanism relates to chronic hyperglycemia, hypoinsulinemia, dyslipidemia and hypertension-all these components in molecular pathways maintain oxidative stress, formation of advanced glycation end-products, microvascular changes, inflammation, and retinal neurodegeneration as one of the key players in diabetes-associated retinal perturbations. In this current review, we discuss the natural history of DR with special emphasis on ongoing inflammation and the key role of vascular endothelial growth factor (VEGF). Additionally, we provide an overview of the principles of diabetic retinopathy treatments, i.e., in laser therapy, anti-VEGF and steroid options.

Quantitative approaches in multimodal fundus imaging: State of the art and future perspectives

When it first appeared, multimodal fundus imaging revolutionized the diagnostic workup and provided extremely useful new insights into the pathogenesis of fundus diseases. The recent addition of quantitative approaches has further expanded the amount of information that can be obtained. In spite of the growing interest in advanced quantitative metrics, the scientific community has not reached a stable consensus on repeatable, standardized quantitative techniques to process and analyze the images. Furthermore, imaging artifacts may considerably affect the processing and interpretation of quantitative data, potentially affecting their reliability. The aim of this survey is to provide a comprehensive summary of the main multimodal imaging techniques, covering their limitations as well as their strengths. We also offer a thorough analysis of current quantitative imaging metrics, looking into their technical features, limitations, and interpretation. In addition, we describe the main imaging artifacts and their potential impact on imaging quality and reliability. The prospect of increasing reliance on artificial intelligence-based analyses suggests there is a need to develop more sophisticated quantitative metrics and to improve imaging technologies, incorporating clear, standardized, post-processing procedures. These measures are becoming urgent if these analyses are to cross the threshold from a research context to real-life clinical practice.

OCT-Based Biomarkers are Associated with Systemic Inflammation in Patients with Treatment-Naïve Diabetic Macular Edema

INTRODUCTION

Diabetic macular edema (DME) is one of the major sight-threatening complications of diabetic retinopathy, which is associated with retinal inflammation. However, it is still unknown whether DME is associated with systemic inflammation. The study aimed to investigate the association between systemic inflammatory and optical coherence tomography (OCT) biomarkers in patients with treatment-naïve center-involving diabetic macular edema (DME) and to further explore the role of systemic inflammation in DME.

METHODS

Medical records including clinical characteristics and ophthalmic examinations were collected from patients with treatment-naïve center-involving DME. Systemic inflammation markers including systemic immune-inflammatory index (SII), neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR) were calculated. OCT biomarkers, including intraretinal cyst (IRC) size, disorganization of retinal inner layers (DRIL), external limiting membrane (ELM)/ellipsoid zone (EZ) integrity, retinal hyperreflective foci (HRF), subretinal fluid (SRF) and vitreomacular (VM) status were evaluated manually. Correlation analysis and multivariable linear regression models were used to investigate the relationship between systemic inflammatory markers and OCT biomarkers.

RESULTS

A total of 82 patients with treatment-naïve center-involving DME were included. The number of HRF on OCT was correlated with SII, NLR, and PLR and positively associated with SII (p < 0.001) in both univariate and multivariate linear regression analyses. The differences remained largely the same during subgroup analysis controlling DM duration, SRF, and ELM/EZ integrity. No significant association was observed between other OCT biomarkers and blood inflammatory markers.

CONCLUSION

Retinal HRF in diabetic macular edema is associated with blood inflammatory markers, which supports the theory of HRF's inflammatory nature and emphasizes the important role of inflammation in DME. SII may be a potential marker for DME treatment decisions.

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.

The Role of Intravitreal Corticosteroids in the Treatment of DME: Predictive OCT Biomarkers

This work aims to summarize predictive biomarkers to guide treatment choice in DME. Intravitreal anti-VEGF is considered the gold standard treatment for centers involving DME, while intravitreal steroid treatment has been established as a second-line treatment in DME. However, more than 1/3 of the patients do not adequately respond to anti-VEGF treatment despite up to 4-weekly injections. Not surprisingly, insufficient response to anti-VEGF therapy has been linked to low-normal VEGF levels in the serum and aqueous humor. These patients may well benefit from an early switch to intravitreal steroid treatment. In these patients, morphological biomarkers visible in OCT may predict treatment response and guide treatment decisions. Namely, the presence of a large amount of retinal and choroidal hyperreflective foci, disruption of the outer retinal layers and other signs of chronicity such as intraretinal cysts extending into the outer retina and a lower choroidal vascular index are all signs suggestive of a favorable treatment response of steroids compared to anti-VEGF. This paper summarizes predictive biomarkers in DME in order to assist individual treatment decisions in DME. These markers will help to identify DME patients who may benefit from primary dexamethasone treatment or an early switch.

Biomarkers to Predict the Success of Treatment with the Intravitreal 0.19 mg Fluocinolone Acetonide Implant in Uveitic Macular Edema

To predict the need for additional local corticosteroids after receiving the 0.19 mg fluocinolone acetonide (FAc) implant in patients with macular edema secondary to non-infectious uveitis previously treated with local peribulbar corticosteroids. The number of corticosteroids required prior FAc, visual acuity, central retinal thickness, ellipsoid zone reflectivity ratio (EZR), and choroidal vascularity index (CVI) were compared between patients who did and did not require additional corticosteroids after FAc implantation. Pearson’s correlation coefficient (R) between putative predictors and the number of adjunctive corticosteroids after FAc implantation were measured; significant candidates were included in a generalized regression model. Patients who required additional corticosteroids after FAc had higher CVI and central retinal thickness as well as worse EZR at subsequent visits (p < 0.05). The number of corticosteroids required prior to FAc implantation (R: 0.49), CVI change from baseline to 6 months (R: −0.41), and central retinal thickness at baseline (R: −0.36) correlated to the number of additional corticosteroids (all p < 0.05). A higher number of corticosteroids per year before FAc implantation was predictive for an increase in corticosteroids required after FAc (odds ratio = 2.65), while a decrease in CVI from baseline to 6 months was inversely correlated (odds ratio = 0.82). Our results suggest that the more corticosteroids prior to FAc and the greater the short-term CVI reducing effect, the less is the chance to get additional corticosteroids after FAc.

Fluocinolone acetonide implant in diabetic macular edema: International experts' panel consensus guidelines and treatment algorithm

Center-involving diabetic macular edema (DME) is a leading cause of vision impairment in working-age adults. While its management is particularly challenging in a poorly compliant population, continuous innovation and the advent of new molecules have improved its outcome. The control of glycemia and of systemic aggravating factors remain essential to slow down progression of disease complications including DME. The indications for macular laser photocoagulation has progressively been phased out as a standard of care and replaced by local intraocular anti-VEGFs biologics and glucocorticoids (GCs). Intravitreal GCs in controlled-release drug delivery systems have allowed to reduce injection frequency and treatment burden. The non biodegradable Fluocinolone Acetonide (FAc) implant allows a long-lasting stabilization of both functional and anatomic improvements. However, adequate patient selection and monitoring through regular follow-up are essential for optimal results. Based on their experience and the latest literature, the aim of the present review is to provide international expert panel consensus on the place of the FAc implant in the treatment algorithm of DME, as well as its safety profile and how to manage it.

Significance of Hyperreflective Foci as an Optical Coherence Tomography Biomarker in Retinal Diseases: Characterization and Clinical Implications

Hyperreflective foci (HRF) is a term coined to depict hyperreflective dots or roundish lesions within retinal layers visualized through optical coherence tomography (OCT). Histopathological correlates of HRF are not univocal, spacing from migrating retinal pigment epithelium cells, lipid-laden macrophages, microglial cells, and extravasated proteinaceous or lipid material. Despite this, HRF can be considered OCT biomarkers for disease progression, treatment response, and prognosis in several retinal diseases, including diabetic macular edema, age-related macular degeneration (AMD), retinal vascular occlusions, and inherited retinal dystrophies. The structural features and topographic location of HRF guide the interpretation of their significance in different pathological conditions. The presence of HRF less than 30 μm with reflectivity comparable to the retinal nerve fiber layer in the absence of posterior shadowing in diabetic macular edema indicates an inflammatory phenotype with a better response to steroidal treatment. In AMD, HRF overlying drusen are associated with the development of macular neovascularization, while parafoveal drusen and HRF predispose to macular atrophy. Thus, HRF can be considered a key biomarker in several common retinal diseases. Their recognition and critical interpretation via multimodal imaging are vital to support clinical strategies and management.

Prognostic biomarkers of chronic diabetic macular edema treated with a fiuocinolone acetonide intravitreal implant

Background

This study aimed to investigate retinal imaging biomarkers, such as disorganization of the retinal inner layers (DRIL) and/or ellipsoid zone (EZ) disruption by spectral domain optical coherence tomography (SD-OCT), and functional outcomes in eyes treated with 0.2 µg/day of a fluocinolone acetonide intravitreal implant (FAc) after an insufficient response to previous treatments.

Methods

This was a retrospective comparative study of 18 eyes (15 patients) with persistent and/or recurrent diabetic macular edema (DME) treated with FAc. Eyes were divided according to the number of prior intravitreal treatments: group 1 (n = 8) with ≤ 6 injections (early switch) and group 2 (n = 10) with > 6 injections (late switch). Outcomes included percentage of eyes with DRIL and/or EZ disruption at baseline and analysis of the best corrected visual acuity (BCVA) using ETDRS letters, central macular thickness (CMT), DRIL, and EZ disruption at the last observation.

Results

Group 2 revealed a significantly higher percentage of DRIL and/or EZ disruption than group 1 (P < 0.05). At the last observation, group 1 revealed a higher percentage of eyes achieving vision stability/ improvement, gaining ≥ 15 letters, and achieving ≥70 letters (P > 0.05 for all comparisons). The mean BCVA gain was 8.8 and 0.7 letters for groups 1 and 2 (P = 0.397). Both groups revealed a significant mean CMT reduction (> 20% reduction from the baseline value), without a significant statistical difference between them (P = 0.749). After treatment, most eyes from both groups showed resolution of DRIL and EZ disruption.

Conclusions

Patients with DME presenting with a lower percentage of DRIL and/or EZ disruption at baseline had better functional outcomes, supporting the possible benefit of an early switch to FAc after insufficient response to previous treatments. Future randomized studies with a larger patient cohort are warranted to confirm our conclusions.

Efficacy and safety of intravitreal Fluocinolone Acetonide microimplant (ILUVIEN®) in patients with chronic diabetic macular edema: 1 year follow-up

PURPOSE

Evaluate the efficacy and safety of intravitreal 0.19 mg fluocinolone acetonide (FAc) micro implant in patients with chronic diabetic macular edema (cDME).

METHODS

Prospective study recruiting subjects with cDME. Inclusion criteria: cDME for at least 2 years documented with OCT imaging; pseudophakia; previous treatments with laser photocoagulation and intravitreal injections of anti-VEGF and/or dexamethasone. Exclusion criteria: phakia; ocular hypertension; tractional component visible on OCT; glaucoma; previous vitrectomy. Outcome measures included best-corrected visual acuity (BVCA), intraocular pressure (IOP), and central macular thickness (CMT), measured 1, 3, 6, and 12 months post-injection. Data were compared with the Friedman test and significance was set at p < 0.05.

RESULTS

A total of 18 eyes with a median duration of cDME of 45 months (25-118 months). The 77% of subjects either maintained or improved their BVCA. About 17% and 33% of subjects showed an improvement of 15 ETDRS letters or more at 3 and 12 months respectively. The 17% and 28% of subjects showed a CMT <250 microns at 3 and 12 months, respectively. The median change in CMT thickness was of -370 and -373.5 microns at 3 and 12 months post-injection respectively (p-value is 0.025). Changes in median IOP at 3 and 12 months post-injection were not statistically significant (p-value is 0.210). Ocular hypertension (OHT) was detected in two eyes (11%).

CONCLUSION

The FAc micro implant has proved efficacy in improving and/or maintaining BVCA in 77% of patients with cDME up to 12 months post-injection. Ocular hypertension is the most common side effect but responds well to topical therapy.