Imaging Hyperreflective Foci as an Inflammatory Biomarker after Anti-VEGF Treatment in Neovascular Age-Related Macular Degeneration Patients with Optical Coherence Tomography Angiography

Application and progress of artificial intelligence technology in the segmentation of hyperreflective foci in OCT images for ophthalmic disease research

With the advancement of retinal imaging, hyperreflective foci (HRF) on optical coherence tomography (OCT) images have gained significant attention as potential biological biomarkers for retinal neuroinflammation. However, these biomarkers, represented by HRF, present pose challenges in terms of localization, quantification, and require substantial time and resources. In recent years, the progress and utilization of artificial intelligence (AI) have provided powerful tools for the analysis of biological markers. AI technology enables use machine learning (ML), deep learning (DL) and other technologies to precise characterization of changes in biological biomarkers during disease progression and facilitates quantitative assessments. Based on ophthalmic images, AI has significant implications for early screening, diagnostic grading, treatment efficacy evaluation, treatment recommendations, and prognosis development in common ophthalmic diseases. Moreover, it will help reduce the reliance of the healthcare system on human labor, which has the potential to simplify and expedite clinical trials, enhance the reliability and professionalism of disease management, and improve the prediction of adverse events. This article offers a comprehensive review of the application of AI in combination with HRF on OCT images in ophthalmic diseases including age-related macular degeneration (AMD), diabetic macular edema (DME), retinal vein occlusion (RVO) and other retinal diseases and presents prospects for their utilization.

Deep Learning in Neovascular Age-Related Macular Degeneration

Background and objectives: Age-related macular degeneration (AMD) is a complex and multifactorial condition that can lead to permanent vision loss once it progresses to the neovascular exudative stage. This review aims to summarize the use of deep learning in neovascular AMD. Materials and Methods: Pubmed search. Results: Deep learning has demonstrated effectiveness in analyzing structural OCT images in patients with neovascular AMD. This review outlines the role of deep learning in identifying and measuring biomarkers linked to an elevated risk of transitioning to the neovascular form of AMD. Additionally, deep learning techniques can quantify critical OCT features associated with neovascular AMD, which have prognostic implications for these patients. Incorporating deep learning into the assessment of neovascular AMD eyes holds promise for enhancing clinical management strategies for affected individuals. Conclusion: Several studies have demonstrated effectiveness of deep learning in assessing neovascular AMD patients and this has a promising role in the assessment of these patients.

Deep learning assisted fluid volume calculation for assessing anti-vascular endothelial growth factor effect in diabetic macular edema

Objective

To develop an algorithm using deep learning methods to calculate the volume of intraretinal and subretinal fluid in optical coherence tomography (OCT) images for assessing diabetic macular edema (DME) patients' condition changes.

Design

Cross-sectional study.

Participants

Treatment-naive patients diagnosed with DME recruited from April 2020 to November 2021.

Methods

The deep learning network, which was built for autonomous segmentation utilizing an encoder-decoder network based on the U-Net architecture, was used to calculate the volume of intraretinal fluid (IRF) and subretinal fluid (SRF). The alterations of retinal vessel density and thickness, and the correlation between best-corrected visual acuity (BCVA) and OCT parameters were analyzed.

Results

2,955 OCT images of fourteen eyes from DME patients with IRF and SRF who received anti-vascular endothelial growth factor (VEGF) agents were obtained. The area under the curve (AUC) of the receiver operating characteristic (ROC) curve of the algorithm was 0.993 for IRF and 0.998 for SRF. The volumes of IRF and SRF were significantly decreased from 1.93 ± 0.58 /1.14 ± 0.25 mm3 (baseline) to 0.26 ± 0.13 /0.26 ± 0.18 mm3 (post-injection), respectively (p = 0.0170 for IRF, and p = 0.0004 for SRF). The Spearman correlation demonstrated that the reduction of IRF volume was negatively correlated with age (coefficient = -0.698, p = 0.006).

Conclusion

We developed a deep learning assisted fluid volume calculation algorithm with high sensitivity and specificity for assessing the volume of IRF and SRF in DME patients. Key words: deep learning; diabetic macular edema; optical coherence tomography.

Longitudinal Evaluation of the Distribution of Intraretinal Hyper-Reflective Foci in Eyes with Intermediate Age-Related Macular Degeneration

PURPOSE

Intraretinal hyper-reflective foci (IHRF) are optical coherence tomography (OCT) risk factors for progression of age-related macular degeneration (AMD). In this study we assess the change in the number and distribution of IHRF over two years.

METHODS

The axial distribution of IHRF were quantified in eyes with intermediate AMD (iAMD) at baseline and 24 months, using a series of 5 sequential equidistant en face OCT retinal slabs generated between the outer border of the internal limiting membrane (ILM) and the inner border of the retinal pigment epithelium (RPE). Following thresholding and binarization, IHRF were quantified in each retinal slab using ImageJ. The change in IHRF number in each slab between baseline and month 24 was calculated.

RESULTS

Fifty-two eyes showed evidence of IHRF at baseline, and all continued to show evidence of IHRF at 24 months (M24). The total average IHRF count/eye increased significantly from 4.67 ± 0.63 at baseline to 11.62 ± 13.86 at M24 (p < 0.001) with a mean increase of 6.94 ± 11.12 (range: - 9 to + 60). Overall, at M24, 76.9% eyes showed an increase in IHRF whereas 15.4% of eyes showed a decrease (3 eyes [5.7%] showed no change). There was a greater number of IHRF and a greater increase in IHRF over M24 in the outer slabs.

CONCLUSIONS

IHRF are most common in the outer retinal layers and tend to increase in number over time. The impact of the distribution and frequency of these IHRF on the overall progression of AMD requires further study.

Relationship between the distribution of intra-retinal hyper-reflective foci and the progression of intermediate age-related macular degeneration

PURPOSE

To assess the relationship between the distribution of intra-retinal hyper-reflective foci (IHRF) on optical coherence tomography (OCT) and progression of intermediate age-related macular degeneration (iAMD) over 2 years.

METHODS

Cirrus OCT volumes of the macula of subjects enrolled in the Amish Eye Study with 2 years of follow-up were evaluated for the presence of iAMD and IHRF at baseline. The IHRF were counted in a series of 5 sequential en face slabs from outer to inner retina. The number of IHRF in each slab at baseline and the change in IHRF from baseline to year 2 were correlated with progression to late AMD at 2 years.

RESULTS

Among 120 eyes from 71 patients with iAMD, 52 eyes (43.3%) of 42 patients had evidence of both iAMD and IHRF at baseline. Twenty-three eyes (19.0%) showed progression to late AMD after 2 years. The total IHRF count increased from 243 at baseline to 604 at 2 years, with a significant increase in the IHRF number in each slab, except for the innermost slab 5 which had no IHRF at baseline or follow-up. The IHRF count increased from 121 to 340 in eyes that showed progression to late AMD. The presence of IHRF in the outermost retinal slabs 1 and 2 was independently associated with a significant risk of progression to late AMD. A greater increase in IHRF count over 2 years in these same slabs 1 and 2 was also associated with a higher risk of conversion to late AMD.

CONCLUSIONS

The risk of progression to late AMD appears to be significantly associated with the distribution and extent of IHRF in the outermost retinal layers. This observation may point to significant pathophysiologic differences of IHRF in inner versus outer layers of the retina.

En-face optical coherence tomography hyperreflective foci of choriocapillaris in central serous chorioretinopathy

The purpose of this study is to evaluate choroidal hyperreflective foci (HRF) changes in central serous chorioretinopathy (CSC) on en-face optical coherence tomography (OCT). Retrospective analysis of 42 patients with unilateral CSC (84 eyes, including fellow eyes for controls) and 42 age- and sex-matched controls. With 4.5 × 4.5 mm macular scans, structural en-face OCT choriocapillaris (CC) slabs were used to calculate the density and number of HRF in acute CSC eyes with serous retinal detachment (SRD), resolved CSC eyes without SRD, unaffected fellow eyes, control eyes, and 1-year follow-up eyes. Based on the 2-disc diameter (3000 μm), the en-face OCT scan was divided into foveal and perifoveal lesion and analyzed to consider the impact of SRF in HRF measurement. Regression analyses were performed on the several factors with HRF number and density in the acute and resolved CSC eyes. The perifoveal density and number of CC HRF was significantly lower in the resolved CSC eyes when compared to the acute CSC eyes (P = 0.002, both), fellow eyes (P = 0.042/density, 0.028/number), and controls (P = 0.021/density, P = 0.003/number). There was no significant difference between the acute CSC eyes, fellow eyes, controls, and 1-year follow-up eyes. As subfoveal choroidal thickness decreased and choroidal vascularity (CVI) increased, the perifoveal density and number of HRF was measured higher with a significant correlation in univariate regression analysis of the acute and resolved CSC eyes (all, P < 0.05). The authors hypothesized that stromal edema induced by choroidal congestion and hyperpermeability has the greatest influence on HRF measurement, possibly affected by inflammatory cells and materials extravasation.

OCTA Biomarker Search in Patients with nAMD: Influence of Retinal Fluid on Time-Dependent Biomarker Response

PURPOSE

Previous studies have identified a link between optical coherence tomography (OCT)-derived and OCT angiography (OCTA)-based parameters in patients with neovascular AMD (nAMD); the latter may serve as direct biomarkers for macular neovascularization (MNV) activity. The aim of this study was to assess the individual influence of retinal thickness (RT) as well as intra- and sub-retinal fluid (IRF, SRF) presence on the treatment response over time as assessed by previously identified OCTA-derived MNV vascular parameters.

METHODS

During the first 3 months of anti-VEGF therapy patients were prospectively followed. RT, SRF and IRF were determined from SSOCT/A (PlexElite, Zeiss) images and using the semi-automated AngioTool software, vessel area (VA), total vessel length (TVL), total number of junctions (TNJ), junction density (JD), vessel density (VD) as well as MNV area were exported. IRF and SRF were identified manually on OCT volume scans .The associations between RT, IRF, and SRF and SSOCTA vascular parameters were analyzed using linear mixed models.

RESULTS

31 eyes of 31 patients with treatment-naïve and OCTA-positive nAMD MNV were included in this analysis. VA, TVL, TNJ, and MNV area show a statistically significant change over time in response to anti-VEGF treatment, even after correcting for the presence of SRF, IRF, or RT (all p < 0.05). This is not the case for JD and VD (both p > 0.05).

CONCLUSIONS

OCTA-based parameters VA, TVL, TNJ, and MNVarea show a strong response to anti-VEGF therapy over time, independent of the presence of IRF, SRF or RT. We conclude that the above listed OCTA parameters could contribute to our understanding of MNV biology and to guide individualized treatment in the future.

TRIAL REGISTRY

The authors confirm that all ongoing and related trials are registered. ClinicalTrials.gov Number: NCT02521142.

Association between inflammatory cytokines in the aqueous humor and hyperreflective foci on optical coherence tomography in patients with neovascular age-related macular degeneration and polypoidal choroidal vasculopathy

Purpose

To investigate the associations between cytokine levels in the aqueous humor (AH) and hyperreflective foci (HF) on spectral-domain optical coherence tomography (SD-OCT) in neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV).

Methods

The prospective study included 63 eyes with nAMD, 44 with PCV, and 43 with cataracts (Controls). AH samples were obtained before anti-vascular endothelial growth factor (VEGF) therapy or cataract surgery. Cytokines interleukin 6 (IL-6), IL-8, IL-10, interferon-inducible protein 10 (IP-10), monocyte chemotactic protein 1 (MCP-1), and VEGF were measured by multiplex bead assay. Best-corrected visual acuity (BCVA), central macular thickness (CMT), and the number of HF were evaluated at baseline and 1 month after anti-VEGF treatment.

Results

No significances difference in IL-6 and IL-8 levels were noted among the three groups (P = 0.370 and P = 0.067). VEGF, IP-10, and IL-10 levels were significantly higher in nAMD and PCV groups than in Controls (all P &lt; 0.05). In nAMD, HF was positively correlated with VEGF (rs = 0.300, P = 0.025) and in eyes with HF group, VEGF and IL-10 were significantly higher than those without HF (P = 0.008 and P = 0.022). In PCV, no correlation was observed between HF and cytokines (all P &gt; 0.05). After anti-VEGF treatment, patients with HF in nAMD and PCV were predisposed to worse visual outcomes (P = 0.022 and P = 0.015) and a significantly greater reduction in CMT (P = 0.001 and P = 0.057). And nAMD patients with HF were more sensitive to anti-VEGF treatment than those without HF (P = 0.029).

Conclusions

In the nAMD group, HF was positively correlated with VEGF. Patients in nAMD with HF had elevated levels of VEGF and IL-10 and responded favorably to anti-VEGF. HF might serve as an inflammatory biomarker and a predictive factor for therapeutic efficacy in patients with nAMD.

Comparison of hyperreflective foci in macular edema secondary to multiple etiologies with spectral-domain optical coherence tomography: An observational study

Background

Hyperreflective foci (HRF) features in macular edema associated with different etiologies may indicate the disease pathogenesis and help to choose proper treatment. The goal of this study is to investigate the retinal microstructural features of macular edema (ME) secondary to multiple etiologies with spectral-domain optical coherence tomography (SD-OCT) and analyze the origin of HRF in ME.

Methods

This was a retrospective study. SD-OCT images were reviewed to investigate macular microstructural features such as the number and distribution of HRF and hard exudates and the internal reflectivity of the cysts. The differences in microstructural features between groups and the correlations between the number of HRF and other parameters were analyzed.

Results

A total of 101 eyes with ME from 86 diabetic (diabetic macular edema, DME) patients, 51 eyes from 51 patients with ME secondary to branch retinal vein occlusion (branch retinal vein occlusion-macular edema, BRVO-ME), 59 eyes from 58 central retinal vein occlusion (central retinal vein occlusion-macular edema, CRVO-ME) patients, and 26 eyes from 22 uveitis (uveitic macular edema, UME) patients were included in this study. The number of HRF, the frequency of hard exudates and the enhanced internal reflectivity of the cysts were significantly different among the groups. The number of HRF in the DME group was significantly higher than that in the other groups (all P < 0.05). The frequency of hard exudates and enhanced internal reflectivity of the cysts in the DME group were significantly higher than ME secondary to other etiologies (all P < 0.001). Within the DME group, the number of HRF in the patients with hard exudates was significantly higher than that in the patients without hard exudates (P < 0.001).

Conclusion

HRF detected with SD-OCT were more frequent in DME patients than in BRVO-ME, CRVO-ME, or UME patients. The occurrence of HRF was correlated with the frequency of hard exudates. HRF may result from the deposition of macromolecular exudates in the retina, which is speculated to be a precursor of hard exudates.

Hyperreflective Foci in Diabetic Macular Edema with Subretinal Fluid: Association with Visual Outcomes after Anti-VEGF Treatment

INTRODUCTION

Objectives of the study were to describe the hyperreflective foci (HRF) on optical coherence tomography angiography in diabetic macular edema (DME) with subretinal fluid (SRF) and explore the association of HRF in the outer retina with photoreceptor integrity and visual outcomes after anti-vascular endothelial growth factor (anti-VEGF) treatment.

METHODS

We retrospectively reviewed 46 eyes (36 patients) with DME treated with anti-VEGF drugs. The following parameters, including best-corrected visual acuity (BCVA), central macular thickness (CMT), the height of SRF, the number of HRF in the superficial capillary plexus, deep capillary plexus, and the outer retina, as well as the integrity of external limiting membrane (ELM) and ellipsoid zone (EZ), were evaluated and compared between the baseline and after 2 monthly injections of anti-VEGF drugs. The relationship between the HRF in the outer retina and the integrity of ELM and EZ, as well as BCVA, was analyzed.

RESULTS

BCVA was significantly improved in DME after anti-VEGF treatment; however, for the subgroup of DME patients with SRF, visual acuity remained unchanged after anti-VEGF treatment (p < 0.05 vs. p = 0.375). The number of HRF (p < 0.05), CMT (p < 0.001), and SRF height (p < 0.001) were significantly reduced, accompanied with partial restoration of ELM and EZ integrity after anti-VEGF injection. The HRF in the outer retina was correlated with the final ELM (p = 0.036) and EZ (p = 0.004) status. The final BCVA was significantly better in eyes with intact ELM (p = 0.002) and EZ at final visit (p < 0.001).

CONCLUSION

The number of HRF in outer retina was negatively associated with the microstructural restoration of ELM and EZ, as well as the visual outcome in DME patients with SRF after anti-VEGF treatment.

Glial-mediated neuroinflammatory mechanisms in age-related macular degeneration

Age-related macular degeneration (AMD) is a neurodegenerative disorder characterized by photoreceptor and retinal pigment epithelium loss often complicated by neovascularization and is one of the leading causes of irreversible vision loss worldwide. However, the precise pathophysiology of AMD remains to date unclear, and there is a dearth of effective therapies for the early stages of the disease. A growing body of evidence has identified microglia-mediated neuroinflammation as a key driver of neuronal damage in AMD, presenting a novel avenue for the development of pharmacological agents targeting this cell population. The local microglial response interacts with other glia as well as engages in crosstalk with peripheral immunological niches. This article presents a review of the current evidence regarding the involvement of glia in the pathophysiology of AMD, an overview of the key immune circuits and effector mechanisms shown to be active in AMD, and potential therapeutic avenues targeting glial involvement.

The Long Pentraxin PTX3 as a New Biomarker and Pharmacological Target in Age-Related Macular Degeneration and Diabetic Retinopathy

Age related macular degeneration (AMD) and diabetic retinopathy (DR) are multifactorial, neurodegenerative and inflammatory diseases of the eye primarily involving cellular and molecular components of the outer and inner blood-retina barriers (BRB), respectively. Largely contributed by genetic factors, particularly polymorphisms in complement genes, AMD is a paradigm of retinal immune dysregulation. DR, a major complication of diabetes mellitus, typically presents with increased vascular permeability and occlusion of the retinal vasculature that leads, in the proliferative form of the disease, to neovascularization, a pathogenic trait shared with advanced AMD. In spite of distinct etiology and clinical manifestations, both pathologies share common drivers, such as chronic inflammation, either of immune (in AMD) or metabolic (in DR) origin, which initiates and propagates degeneration of the neural retina, yet the underlying mechanisms are still unclear. As a soluble pattern recognition molecule with complement regulatory functions and a marker of vascular damage, long pentraxin 3 (PTX3) is emerging as a novel player in ocular homeostasis and a potential pharmacological target in neurodegenerative disorders of the retina. Physiologically present in the human eye and induced in inflammatory conditions, this protein is strategically positioned at the BRB interface, where it acts as a “molecular trap” for complement, and modulates inflammation both in homeostatic and pathological conditions. Here, we discuss current viewpoints on PTX3 and retinal diseases, with a focus on AMD and DR, the roles therein proposed for this pentraxin, and their implications for the development of new therapeutic strategies.

Hyperreflective Foci and Subretinal Fluid Are Potential Imaging Biomarkers to Evaluate Anti-VEGF Effect in Diabetic Macular Edema

Purpose: The aim was to investigate the effect and underlying mechanism of anti-vascular endothelial growth factor (anti-VEGF) in diabetic macular edema (DME) by optical coherence tomography angiography (OCTA). Methods: Twenty-five eyes in 18 treatment-naïve patients with DME were included. All eyes were imaged by OCTA at baseline and 1 week after monthly intravitreal aflibercept injection (IAI). Visual acuity was measured as best corrected visual acuity (BCVA). Additional parameters were evaluated by OCTA, including central macular thickness (CMT), the number of hyperreflective foci (HRF), foveal avascular zone (FAZ), vessel density (VD) in the deep capillary plexus (DCP), the en-face area of cystoid edema in DCP segmentation, and subretinal fluid (SRF) height. Results: The mean time between baseline and final follow-up by OCTA was 79.24 ± 38.15 (range, 28-163) days. Compared with baseline, BCVA was increased significantly after the 3rd IAI, while CMT was decreased significantly from the 1st IAI. SRF height and the area of cystoid edema in DCP segmentation were decreased significantly after the 2nd IAI compared with baseline. The number of HRF was decreased significantly after the 1st IAI (8.87 ± 9.38) compared with baseline (11.22 ± 10.63). However, FAZ's area and perimeter as well as VD in DCP showed no significant changes post-treatment. Conclusion: Anti-VEGF is effective in treating DME, improving visual acuity and decreasing macular edema. The decreased HRF indicates anti-inflammatory effects of aflibercept to deactivate retinal microglia/macrophages. The decreased cystoid edema and SRF height indicated improved drainage function of Müller glial cells and retinal pigment epithelium after IAI.

Optical Coherence Tomography Angiography Characteristics Serve as Retinal Vein Occlusion Therapeutic Biomarkers for Dexamethasone Intravitreal Implant

Background

Retinal vein occlusion (RVO) is the second most common vision-threatening retinal vascular disease. Intravitreal dexamethasone implant has been applied to treat macular edema secondary to RVO (RVO-ME). However, the alteration of morphologic features detected with optical coherence tomography angiography (OCTA) has not been fully studied in RVO-ME patients before and after the treatment.

Objective

This study is aimed at identifying potential therapeutic targets in RVO with integrative bioinformatic analysis and compares the OCTA characteristics alterations in patients with RVO-ME receiving injection of dexamethasone intravitreal implant.

Methods

Bioinformatic analysis was analyzed in GSE101398 dataset from the Gene Expression Omnibus database. Multiple functional enrichment analyses were performed, and protein-protein interaction network was constructed to visualize the key node genes. Eleven eyes with RVO-ME were examined with OCTA before and after intravitreal dexamethasone implant. The OCTA parameters, including macular thickness, vessel density, foveal avascular zone parameters, the number of hyperreflective foci (HRF), area of cystoid edema, and subretinal fluid (SRF), were compared. The correlation was analyzed between best-corrected visual acuity (BCVA) and OCTA parameters.

Results

A total of 79 differentially expressed genes were identified. Functional enrichment analyses revealed the enriched inflammatory events in RVO. In RVO-ME, Pearson correlation revealed that baseline BCVA was positively correlated with the area of SRF and central macular thickness, while no correlation was detected between baseline BCVA and HRF number or the area of cystoid edema. The visual acuity improved, and the central macular thickness was decreased after intravitreal dexamethasone implant injection. Besides, the number of HRF, the area of cystoid edema, and SRF were significantly alleviated after dexamethasone intravitreal injection.

Conclusion

Retinal inflammation plays a crucial role in RVO pathogenesis. The imaging biomarkers of RVO including Müller glial intracellular edema, and retinal pigment epithelium dysfunction, could be assessed in OCTA and attenuated by intravitreal dexamethasone implant effectively.