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

Hyperreflective Foci Along the Retinal Pigment Epithelium Predict the Onset of Large Choroidal Hypertransmission Defects in Age-Related Macular Degeneration

PURPOSE

In eyes with intermediate age-related macular degeneration (iAMD), we separately quantified the hyperreflective foci (HRF) along the retinal pigment epithelium (rpeHRF) and the intraretinal HRF (iHRF) to determine if the location of the HRF predicted the progression from iAMD to the onset of large persistent choroidal hypertransmission defects (hyperTDs).

DESIGN

Post hoc subgroup cohort analysis of a prospective study.

METHODS

A retrospective analysis was performed on a prospective natural history database of eyes with AMD imaged using swept-source optical coherence tomography (SS-OCT). En face images derived from choroidal slabs positioned 64 to 400 µm beneath Bruch membrane were used with a semiautomated algorithm to identify and quantify hypotransmission defects (hypoTDs) attributable to either iHRF or rpeHRF within a 5-mm fovea-centered circle. iHRF were identified on corresponding B-scans as hyperreflective lesions within the neurosensory retina, and rpeHRF were identified as areas of retinal pigment epithelium thickening. Multivariable survival analysis was performed to determine if the area measurements of either iHRF or rpeHRF were more likely to predict the onset of the first large persistent hyperTD.

RESULTS

Of the 171 eyes with iAMD included in this study, 82 (48%) developed at least 1 large hyperTD during a median follow-up of 59.1 months. Univariable Cox regression analyses showed that rpeHRF area (P < .001), iHRF area (P = .003), and drusen volume (P < .001) were all significantly associated with the onset of the first large persistent hyperTD. However, a multivariable Cox regression model showed that only the rpeHRF area remained a significant predictor of disease progression (P < .001).

CONCLUSIONS

In iAMD eyes, the area of rpeHRF was more predictive of disease progression than either the drusen volume or iHRF, which suggests that these rpeHRF serve as harbingers of focal atrophy formation and may predict where hyperTDs form.

Artificial intelligence-based assessment of imaging biomarkers in epiretinal membrane surgery

PurposeThis study investigated the applicability of a validated AI-algorithm for analyzing different retinal biomarkers in eyes affected by epiretinal membranes (ERMs) before and after surgery.MethodsA retrospective study included 40 patients surgically treated for ERMs removal between November 2022 and January 2024. Pars plana vitrectomy with ERM/ILM peeling was performed by a single experienced surgeon. A validated AI algorithm was used to analyze OCT scans, focusing on intraretinal fluid (IRF) and subretinal fluid (SRF) volumes, external limiting membrane (ELM) and ellipsoid zone (EZ) interruption percentages and hyper-reflective foci (HRF) counts.ResultsPostoperative best corrected visual acuity (BCVA) significantly improved (p < 0.01), and central macular thickness (CMT) decreased from 483.61 ± 96.32 to 386.82 ± 94.86 µm (p = 0.001). IRF volume reduced from 0.283 ± 0.39 mm3 to 0.142 ± 0.27 mm3 (p = 0.036) particularly in the central 1 mm-circle. SRF, HRF and EZ/ELM interruption percentages exhibited no significant differences (p > 0.05). Significant correlations (p < 0.05) were found between preoperative BCVA and postoperative BCVA (r = 0.45); CMT reduction and postoperative BCVA (r = 0.42), preoperative IRF and Visual Recovery (r = -0.48), ELM and EZ interruption and visual recovery (r = -0.43 and r = -0.47 respectively). Multivariate analysis demonstrated that fluid distribution, especially in the central subfield, correlated with BCVA recovery (R2 = 0.38; p < 0.05; Pillai's Trace = 0.79).ConclusionThe study highlights AI's potential in quantifying OCT biomarkers in ERMs surgery. The findings suggest that improved BCVA is associated with reduced CMT, IRF, and redistribution of IRF towards the periphery. EZ and ELM integrities remain crucial prognostic factors, emphasizing the importance of the preoperative analysis.

Updates on novel and traditional OCT and OCTA biomarkers in nAMD

Predictivity of optical coherence tomography (OCT) examination for the development of neovascular age-related macular degeneration (nAMD) was demonstrated to be superior compared to other methods, suggesting it as an elective method for screening purposes. Moreover, OCT and OCT angiography (OCTA) have enabled us to provide accurate prognostic information to nAMD patients. Along with well-known prognostic biomarkers, such as the presence of reticular pseudodrusen, the volume of the pigment epithelial detachment (PED), subretinal fluid (SRF), intraretinal fluid (IRF) and hyperreflective foci (HRF), emerging parameters show promising results and may allow a further refinement of prediction and customization of treatment and follow up strategies. This review of the literature discusses the main OCT and OCTA biomarkers reported in literature for nAMD, with a special focus on recent updates on the subject. Future perspectives of clinical applications include the development of artificial intelligence models considering all the described biomarkers to allow automatic and detailed characterization of each lesion based on imaging information.

OCT predictors of retinal atrophy in neovascular age-related macular degeneration treated with aflibercept

AIM

To identify optical coherence tomography (OCT) features present at the diagnosis of neovascular age-related macular degeneration (nAMD) that could predict retinal atrophy (RA) and visual performance in patients treated with intravitreal aflibercept.

METHODS

OCT data collected at the time of nAMD diagnosis (T0), after the first (T1) and third (T2) intravitreal aflibercept injection, and 5y post-diagnosis (T3) were analyzed. The study included 46 eyes from patients undergoing treatment. The association of OCT features with RA and visual acuity (VA) development over time were evaluated.

RESULTS

Patients with RA at T3 exhibited worse VA (35.19±5.7 vs 8.90±2.3, P<0.001) and a lower rate of improvement or stability at T2 (90.48% vs 56.00%, P=0.019) and T3 (85.71% vs 8.00%, P<0.001). The development of RA at T3 was linked with type 2 macular neovascularization (MNV; 4.76% vs 36.00%, P=0.013), thinner outer nuclear layer (ONL, 88.89±7.82 µm vs 71.38±14.14 µm, P=0.033), presence of intraretinal fluid (IRF, 42.86% vs 80.00%, P=0.014), presence of IRF without subretinal fluid at T0 (SRF, 4.76% vs 32.00%, P=0.027), and reduced central foveal thickness at T3 (CFT, 190.14±22.79 µm vs 124.32±14.35 µm, P<0.001). The presence of SRF with or without IRF at the diagnosis was comparable between the two groups (90.48% vs 68.00%; P=0.084).

CONCLUSION

Type 2 MNV, reduces ONL and CFT, and IRF presence at baseline may signal a higher risk of RA in treatment-naive nAMD patients, underscoring the importance of these OCT features in early risk assessment and management strategies.

NOVEL MULTIMODAL IMAGING IN BILATERAL DIFFUSE UVEAL MELANOCYTIC PROLIFERATION AND CHANGE IN THE FINDINGS DURING FOLLOW-UP AND TREATMENT

PURPOSE

To describe the advanced multimodal imaging findings of patients with bilateral diffuse uveal melanocytic proliferation and the changes in these findings over time.

METHODS

Fundus photography, fundus autofluorescence, fundus fluorescein angiography, spectral domain optical coherence tomography, B-scan ultrasonography, and ultrasound biomicroscopy images of the patients diagnosed with bilateral diffuse uveal melanocytic proliferation at a single institution between years 2006 and 2023 were evaluated.

RESULTS

Sixteen eyes of eight patients with bilateral diffuse uveal melanocytic proliferation were included. The median age was 68 years (range: 49-77 years), and the median follow-up time was 11 months (range: 1-79 months). The most common fundus photography findings were pigmentary changes and diffuse orange pigment patches in the posterior pole. The giraffe/leopard pattern of hyperfluorescence on the posterior pole was the most prominent finding in fundus autofluorescence and fluorescein angiography. Different from previous reports, intraretinal hyperreflective foci, outer retinal tubulations, subretinal fibrosis, and bacillary layer detachment in optical coherence tomography; optic disc hyperfluorescence and peripheral vascular leakage in fluorescein angiography; 360° ciliary body thickening; and anterior rotation of the ciliary body in ultrasound biomicroscopy were detected.

CONCLUSION

We presented various novel multimodal imaging features of bilateral diffuse uveal melanocytic proliferation that may warrant updating current diagnostic criteria and their changes over time. Our newly defined findings also suggest a possible inflammatory component to bilateral diffuse uveal melanocytic proliferation pathogenesis, which may have implications for treatment.

Foveal crack sign and macular pattern dystrophy

PURPOSE

To determine if eyes with the foveal crack sign (FCS) in macular pattern dystrophy (MPD) progress to macular holes, and if FCS occurs in the context of hyperreflective foci (HRF) that do not reach the threshold of FCS.

PATIENTS AND METHODS

A retrospective chart review of eyes with MPD was conducted in the Atrium Health Wake Forest Baptist medical system. 56 eyes from 32 patients identified as having macular pattern dystrophy were identified. Demographic data were collected from charts and spectral domain optical coherence tomographs (SD-OCTs) were analyzed.

RESULTS

8 eyes from 6 patients were found to have an FCS-positive OCT at any point at or following their initial diagnosis of MPD. One eye developed a full-thickness stage 4 macular hole during follow-up. There was no significant difference in macular hole development between MPD eyes with and without FCS (p =.1429). There was a significant difference in FCS development between MPD eyes with and without HRF (p =.0063).

CONCLUSIONS

The data did not show a significant difference in macular hole generation between eyes with and without FCS, unlike the situation of FCS in eyes post vitrectomy for retinal detachment repair. The significant association between HRF and FCS suggests that the two signs may have a related pathophysiology and may represent different stages in a common degenerative process. Further work is needed to better characterize the relationship of FCS and HRF and to determine if FCS has different implications in the different clinical contexts in which it appears.

Predictors of macular edema recurrence and visual outcomes in branch retinal vein occlusion treated with aflibercept or ranibizumab

PURPOSE

To investigate the risk factors for visual outcomes and recurrence of macular edema (ME) in branch retinal vein occlusion (BRVO) after intravitreal injection (IVI) of anti-vascular endothelial growth factor (anti-VEGF) agents.

METHODS

Thirty eyes of 30 patients with recent-onset, treatment naive BRVO with ME receiving IVI aflibercept and ranibizumab in a tertiary care hospital were enrolled retrospectively. Treatment response was classified into "responsive group" and "recurrent/refractory group" by absence or presence of ME after consecutive monthly IVI anti-VEGF therapy. The correlation between the optical coherent tomography and fluorescein angiography features and treatment response was analyzed during a 1-year follow-up period.

RESULTS

In thirty eyes, the logarithm of the minimum angle of resolution best-corrected visual acuity (BCVA) improved from 0.69 ± 0.39 to 0.55 ± 0.48, and was comparable in the responsive and recurrent/refractory groups (p = 0.683). At baseline, the recurrent group had a higher prevalence of subretinal fluid (SRF), disruption in the ellipsoid zone, and greater central macular thickness (CMT) than in the responsive group. Worse initial BCVA, presence of intraretinal fluid (IRF) and external limiting membrane disruption at the third month after treatment was associated with poorer final BCVA (p = 0.021, 0.014, and 0.044, respectively). Cases receiving three consecutive loading injections indicated better final BCVA (p = 0.008). Patients receiving aflibercept required fewer injections than those receiving ranibizumab (p = 0.005).

CONCLUSIONS

Baseline predictors of ME recurrence included SRF presence, outer retinal layer disruptions, and greater CMT. Baseline vision, IRF at 3rd month, and the number of consecutive loading injection were correlated with visual outcomes.

Dicer Loss in Müller Glia Leads to a Defined Sequence of Pathological Events Beginning With Cone Dysfunction

Purpose

The loss of Dicer in Müller glia (MG) results in severe photoreceptor degeneration, as it occurs in retinitis pigmentosa or age-related macular degeneration; however, the sequence of events leading to this severe degenerative state is unknown. The aim of this study was to conduct a chronological functional and structural characterization of the pathological events in MG-specific Dicer-conditional knockout (cKO) mice in vivo and histologically.

Methods

To delete Dicer and mature microRNAs (miRNAs) in MG, two conditional Dicer1 knockout mouse strains (Rlbp-CreER:tdTomato:Dicer-cKOMG and Glast-CreER:tdTomato:Dicer-cKOMG) were created. Optical coherence tomography (OCT), electroretinograms (ERGs), and histological analyses were conducted to investigate structural and functional changes up to 6 months after Dicer deletion.

Results

Dicer/miRNA loss in MG leads to (1) impairments of the area spanning from the external limiting membrane (ELM) to the retinal pigment epithelium (RPE), (2) cone photoreceptor dysfunction, and (3) retinal remodeling and functional loss of the inner retina at 1, 3, and 6 months after Dicer loss, respectively, in both of the knockout mouse strains. Furthermore, in the Rlbp-CreER:tdTomato:Dicer-cKOMG strain, rod photoreceptor impairment was found 4 months after Dicer depletion (4) accompanied by alteration of RPE integrity (5).

Conclusions

MG Dicer loss in the adult mouse retina impacts cone function prior to any measurable changes in rod function, suggesting a pivotal role for MG Dicer and miRNAs in supporting cone health. A partially impaired RPE, however, seems to accelerate rod degeneration and overall degenerative events.

Foveal hyper-reflective vertical lines detected by optical coherence tomography: Imaging features, literature review and differential diagnoses

PURPOSE

To describe foveal hyper-reflective vertical lines (FVL) as a specific morphological finding on structural spectral-domain optical coherence tomography (SD-OCT) and discuss its differential diagnosis.

METHODS

Observational case series. Ten patients (10 eyes) with FVL were meticulously examined at the Ophthalmology Department, Shaare Zedek Medical Center, Jerusalem, Israel. Detailed analysis of SD-OCT findings, clinical records, and retinal imaging was conducted to establish correlations between FVL and various underlying conditions.

RESULTS

We established the following list of settings, supported by the clinical context and ancillary investigations, in which SD-OCT displayed FVL: inflammation (1 eye), mechanical (1 eye), resorption of fluids of various origins (4 eyes), macular telangiectasia (1 eye), age-related macular degeneration (1 eye), diabetic retinopathy (1 eye) and scar (1 eye).

CONCLUSIONS

FVL can be observed in various underlying conditions. Recognition of this pattern and formulation of an appropriate differential diagnosis is of interest for correctly diagnosing and treating patients whose structural OCT harbors this yet overlooked finding.

Elevated hyperreflective foci as a novel characteristic in idiopathic epiretinal membrane by optical coherence tomography angiography

PURPOSE

The objective of this study was to analyze hyperreflective foci at the vitreous-retinal interface in cases of idiopathic epiretinal membrane (iERM) using enface-OCT.

METHODS

This study included 47 patients (52 eyes) diagnosed with iERM between January 2020 and July 2023. We observed changes in hyperreflective foci in the macular area at each stage of iERM using OCTA on a 6 mm slab of the VRI. Evaluations included the density and percentage of hyperreflective foci of the epiretinal membrane at each stage, as well as the relationship between hyperreflective foci density and other OCT parameters, such as macular thickness and changes in macular superficial vascular density.

RESULTS

Statistically significant differences in hyperreflective foci density and percentage were observed across the four stages of patients (p < 0.05). Additionally, statistically significant differences in superficial vascular density were noted among the four stages (p < 0.05). Hyperreflective foci area percentage and density correlated significantly with hyperreflective foci, FAZ area, and FAZ perimeter (p < 0.005). However, no correlation was found between hyperreflective foci density and area percentage with superficial vascular density and superficial perfusion density (p > 0.05).

CONCLUSION

Hyperreflective foci were identified in all stages of iERM, with their number and density increasing as the disease progressed.

Inner retinal hyper-reflective foci number correlates with flood-illumination adaptive optics ophthalmoscopy grading and systemic organ involvement in patients with Fabry disease

OBJECTIVES

To determine the correlation of inner retinal hyper-reflective foci (HRFs) number with Flood-illumination Adaptive Optics Ophthalmoscopy (FIAOO) grading and systemic organ involvement in a cohort of patients with Fabry disease (FD).

METHODS

Observational and cross-sectional study. Thirty-two eyes of 16 genetically proven FD patients (11 females) were included in the analysis. Data regarding therapeutic regimen and organ involvement (heart, kidney, and brain) of each patient were reviewed. Patients underwent full ophthalmological examination including best-corrected visual acuity, retinography, spectral domain optical coherence tomography and FIAOO imaging grading of retinal vessels. The number of inner-retinal HRFs was determined within the central 2500 μm at the foveal level in each patient and correlation with ocular imaging findings and systemic involvement parameters was assessed through Spearman correlation analysis and Generalized Linear Models (GLM) with a robust Huber White standard error estimation.

RESULTS

Inner retinal HRFs number showed a significant association with male gender, use of enzyme replacement therapy and presence of retinal vessel tortuosity (all p < 0.001). Severity of NHYA class and presence of cornea verticillata reached a quasi-significant association (p = 0.089 and p = 0.07, respectively). Increase of FIAOO grading was associated to increased HRFs number (p < 0.001) and increase in estimated glomerular filtration rate was inversely associated with HRFs number (p = 0.04).

CONCLUSIONS

Inner retinal HRF number correlated with organ involvement and ocular imaging findings in FD patients. They may represent a biomarker of disease severity in diagnosed patients and their presence should enhance the suspect of FD in the appropriate clinical setting.

[Optical coherence tomography biomarkers for neovascular age-related macular degeneration : Relevance for the diagnosis, treatment and prognosis]

Comprehensive multimodal imaging is essential for the precise clinical diagnostics of neovascular age-related macular degeneration (nAMD). Noninvasive optical coherence tomography (OCT) is of prime importance regarding the baseline examination, follow-up and monitoring during treatment. The OCT imaging in nAMD eyes enables a high-resolution assessment of the retinal micromorphology, which can be considerably disturbed in different layers. A large number of pathological OCT alterations represent distinct micromorphological OCT biomarkers. These should be taken into account in the assessment of OCT images. This article covers the following important biomarkers: intraretinal, subretinal and subpigment epithelial fluid, outer retinal tubulations, ellipsoid zone integrity, hyperreflective foci, subretinal drusenoid deposits, onion sign, hyporeflective prechoroidal cleft, double layer sign, subretinal hyperreflective material and bacillary layer detachment.

Non-exudative OCT findings in neovascular AMD

In this narrative review we describe the main optical coherence tomography biomarkers appearing in eyes with neovascular age-related macular degeneration (AMD) that do not directly correspond to exudation. We highlight those signs that may mimic exudation and therefore do not require active treatment, such as outer retinal tubulations, pseudocysts, lipid globules, or hyporeflective wedges. Other signs may indicate impending exudation such as hyperreflective foci or shallow irregular retinal pigment epithelium elevation, and therefore should be carefully monitored. We also review and summarize the different origins of subretinal hyperreflective material and describe the main signs of degeneration seen in eyes with AMD, such as outer retinal tubulation, thinning of the retinal layers, outer retinal atrophy, and choroidal changes.

Dicer loss in Müller glia leads to a defined sequence of pathological events beginning with cone dysfunction

Purpose

The loss of Dicer in Müller glia (MG) results in severe photoreceptor degeneration as it occurs in retinitis pigmentosa or AMD. However, the sequence of events leading to this severe degenerative state is unknown. The aim of this study was to conduct a chronological functional and structural characterization of the pathological events in MG-specific Dicer-cKO mice in vivo and histologically.

Methods

To delete Dicer and mature microRNAs (miRNAs) in MG, two conditional Dicer1 knock-out mouse strains namely RlbpCre:Dicer-cKO MG and GlastCre:Dicer-cKO MG, were created. Optical coherence tomography (OCT), electroretinograms (ERGs) as well as histological analyses were conducted to investigate structural and functional changes up to six months after Dicer deletion.

Results

Dicer/miRNA loss in MG leads to 1) impairments of the external limiting membrane (ELM) - retinal pigment epithelium (RPE), 2) cone photoreceptor dysfunction and 3) retinal remodeling and functional loss of the inner retina, 1, 3 and 6 months after Dicer loss, respectively, in both strains. Furthermore, in the Rlbp:Dicer-cKO MG strain, rod photoreceptor impairment was found 4 months after Dicer depletion (4) accompanied by alteration of RPE integrity (5).

Conclusions

MG Dicer loss in the adult mouse retina impacts cone function prior to any measurable changes in rod function, suggesting a pivotal role for MG Dicer and miRNAs in supporting cone health. A partially impaired RPE however seems to accelerate rod degeneration and overall degenerative events.

Genotype-Phenotype Correlations and Genetic Risk Assessment in Age-Related Macular Degeneration

Age-related macular degeneration (AMD), the leading cause of irreversible vision loss in the elderly, presents researchers and clinicians with a complex challenge due to its multifaceted etiology and phenotype. The difficulty in developing effective treatments, especially for atrophic AMD, is an ongoing concern. Genetics plays a significant role in AMD's pathogenesis, with 52 variants in 34 loci linked to AMD based on a genome-wide association study. The association of genetic burden to the phenotypic and progression features of AMD is a current focus in the field. This perspective presents available information on phenotype-genotype correlations in AMD and on future directions in AMD genetic research which may be further corroborated with specific phenotypes and progression patterns to eventually develop personalized follow-up and therapeutic strategies.

Quantitative Multimodal Imaging Characterization of Intraretinal Cysts versus Degenerative Pseudocysts in Neovascular Age-Related Macular Degeneration

OBJECTIVE

To differentiate intraretinal fluid (IRF) cysts from degenerative pseudocysts in neovascular age-related macular degeneration (AMD) by quantitative multimodal imaging.

DESIGN

Observational, cross-sectional.

PARTICIPANTS

Patients affected by macular neovascularization secondary to AMD.

METHODS

All patients were analyzed by OCT, OCT angiography (OCTA), and dense automatic real-time (ART) OCTA. New-onset cysts were considered IRF, whereas those cysts that were found to be persistent for at least 3 months were categorized as degenerative pseudocysts. Intraretinal cysts were automatically segmented to calculate cyst circularity. Peri-cyst space was quantitatively analyzed to assess the presence of perfusion signal and hyperreflective foci (HF).

MAIN OUTCOME MEASURES

Best-corrected visual acuity, cyst circularity, peri-cyst perfusion, peri-cyst HF, fibrosis, and outer retinal atrophy.

RESULTS

We analyzed 387 cysts collected from 35 eyes of 35 patients with neovascular AMD (14 men; mean age, 80 ± 5 years). We classified 302 IRF cysts and 85 degenerative pseudocysts. Intraretinal fluid cysts were characterized by significantly higher circularity (0.86; range, 0.81-0.91), perfusion signal in the peri-cyst space, and peri-cyst HF in 89% of cases (all P < 0.05). Degenerative pseudocysts showed significantly lower circularity (0.68; range, 0.64-0.76), no perfusion signal in the peri-cyst space, and peri-cyst HF in only 29% of cases (all P < 0.05). The adopted quantitative metrics significantly correlated with disease duration, number of injections, fibrosis, and outer retinal atrophy.

CONCLUSIONS

Intraretinal fluid cysts can be discriminated from degenerative pseudocysts using a quantitative multimodal imaging approach. These findings are clinically relevant and should be included in future training models for artificial intelligence algorithms to improve the diagnostic power and fluid monitoring in neovascular AMD.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Imaging the eye as a window to brain health: frontier approaches and future directions

Recent years have seen significant advances in diagnostic testing of central nervous system (CNS) function and disease. However, there remain challenges in developing a comprehensive suite of non- or minimally invasive assays of neural health and disease progression. Due to the direct connection with the CNS, structural changes in the neural retina, retinal vasculature and morphological changes in retinal immune cells can occur in parallel with disease conditions in the brain. The retina can also, uniquely, be assessed directly and non-invasively. For these reasons, the retina may prove to be an important "window" for revealing and understanding brain disease. In this review, we discuss the gross anatomy of the eye, focusing on the sensory and non-sensory cells of the retina, especially microglia, that lend themselves to diagnosing brain disease by imaging the retina. We include a history of ocular imaging to describe the different imaging approaches undertaken in the past and outline current and emerging technologies including retinal autofluorescence imaging, Raman spectroscopy, and artificial intelligence image analysis. These new technologies show promising potential for retinal imaging to be used as a tool for the diagnosis of brain disorders such as Alzheimer's disease and others and the assessment of treatment success.

Analysis of factors affecting prognosis of the visual acuity and baseline risk factors for subretinal fibrosis in neovascular age-related macular degeneration patients

Background

To evaluate factors affecting visual acuity prognosis in patients with neovascular age-related macular degeneration (nAMD) following anti-vascular endothelial growth factor (anti-VEGF) therapy via intravitreal injection and to identify baseline risk factors for subretinal fibrosis (SF).

Methods

A retrospective study of 64 nAMD eyes treated with intravitreal anti-VEGF treatment over 12 months of follow-up was conducted. Demographic and optical coherence tomography characteristics at baseline were recorded to explore the relevant factors affecting visual acuity outcome. Find baseline risk factors for SF development. The primary baseline measures included OCT qualitative and quantitative indicators, and optical coherence tomography angiography (OCTA) quantitative features.

Results

BCVA (logMAR) at 12 months was positively correlated with age (r = 0.258, p = 0.040), baseline BCVA (r = 0.749, p < 0.001), central macular thickness (CMT) (r = 0.413, p < 0.001), subretinal hyperreflective material (SHRM) (r = 0.304, p = 0.014), intraretinal fluid (IRF) (r = 0.423, p < 0.001), type 2 macular neovascularization (MNV) (r = 0.272, p = 0.029), and ellipsoidal zone breaks (r = 0.299, p = 0.016), and hyperreflective foci (HF) (r = 0.264, p = 0.035). Eyes with SF had worse baseline BCVA (p < 0.001), greater CMT (p = 0.009), and a higher prevalence of IRF (p = 0.005), type 2 MNV (p = 0.001), SHRM (p = 0.012), and HF (p = 0.028). Logistic binary regression analysis showed that baseline BCVA (logMAR) (OR = 0.02, 95% CI: 0.00-0.45, p = 0.013), HF (OR = 0.11, 95% CI: 0.01-0.95, p = 0.045), and type 2 MNV (OR = 0.08, 95% CI: 0.01-0.88, p = 0.039) were independent risk factors of subretinal fibrosis. As for quantitative OCTA parameters, eyes with subretinal fibrosis had a larger microvascular lesion size (p = 0.003), larger vessels area (p = 0.002), higher number of vessel junctions (p = 0.042) and endpoints (p = 0.024), longer total vessel length (p = 0.005), and lower vessel length density (p = 0.042).

Conclusion

This study enplores baseline OCT and OCTA characteristics associated with subretinal fibrosis in nAMD patients. This information can help predict the occurrence and progression of subretinal fibrosis, potentially leading to more personalized treatment approaches for nAMD patients.

Comparison between spectral-domain optical coherence tomography-based and partial coherence interferometry-based biometry

We compared axial length (AL) measurements using spectral-domain optical coherence tomography (SD-OCT)-based and partial coherence interferometry (PCI)-based biometry in eyes with various chorioretinal diseases. Medical records were retrospectively analyzed in 123 eyes from 73 patients who underwent AL measurements using SD-OCT and PCI. AL values were highly consistent by both measurements (ICC = 0.996 in SD-OCT and 0.995 in PCI-based biometry). The mean difference in AL between the two instruments was - 0.09 ± 0.17 mm, which was significant (P < 0.001). There was a strong correlation between the measurements obtained using the two instruments (r = 0.982, P < 0.001). The 95% limits of agreement were - 0.43 to 0.25 mm, and the agreement of AL in the Bland-Altman analysis showed a difference. The difference in measurements was not associated with the difference in central retinal thickness (r = 0.033, P = 0.720). However, the presence of an epiretinal membrane affected the difference in measurements, unlike in other chorioretinal diseases (P = 0.014). SD-OCT-based biometry showed a good correlation with PCI-based biometry in the measurement of AL; however, the mean AL between the two instruments was significantly different. Therefore, AL measurements made using SD-OCT-based and PCI-based biometry are not interchangeable.

Topographic and quantitative correlation of structure and function using deep learning in subclinical biomarkers of intermediate age-related macular degeneration

To examine the morphological impact of deep learning (DL)-quantified biomarkers on point-wise sensitivity (PWS) using microperimetry (MP) and optical coherence tomography (OCT) in intermediate AMD (iAMD). Patients with iAMD were examined by OCT (Spectralis). DL-based algorithms quantified ellipsoid zone (EZ)-thickness, hyperreflective foci (HRF) and drusen volume. Outer nuclear layer (ONL)-thickness and subretinal drusenoid deposits (SDD) were quantified by human experts. All patients completed four MP examinations using an identical custom 45 stimuli grid on MP-3 (NIDEK) and MAIA (CenterVue). MP stimuli were co-registered with corresponding OCT using image registration algorithms. Multivariable mixed-effect models were calculated. 3.600 PWS from 20 eyes of 20 patients were analyzed. Decreased EZ thickness, decreased ONL thickness, increased HRF and increased drusen volume had a significant negative effect on PWS (all p < 0.001) with significant interaction with eccentricity (p < 0.001). Mean PWS was 26.25 ± 3.43 dB on MP3 and 22.63 ± 3.69 dB on MAIA. Univariate analyses revealed a negative association of PWS and SDD (p < 0.001). Subclinical changes in EZ integrity, HRF and drusen volume are quantifiable structural biomarkers associated with reduced retinal function. Topographic co-registration between structure on OCT volumes and sensitivity in MP broadens the understanding of pathognomonic biomarkers with potential for evaluation of quantifiable functional endpoints.

Fingerprint sign of the Henle fibre layer in epiretinal membrane: a cross-sectional and longitudinal study

PURPOSE

To investigate the incidence and distribution of fingerprint-like microwaves in the Henle fibre layer (HFL) of the eyes with epiretinal membrane (ERM).

METHODS

Patients with idiopathic ERM were included. The fingerprint sign was defined using en-face optical coherence tomography images of the HFL, and its extent was classified into three grades.

RESULTS

At baseline, fingerprint sign was found in 70 of 83 (84.3%) eyes with ERM and was more frequently observed in eyes with a higher ERM stage (P < 0.001). Its extent increased (P < 0.001) with an increase in ERM stage or the central macular thickness (P < 0.001). Best corrected visual acuity (BCVA) was worse in eyes with a fingerprint sign than in those without (P = 0.024). Metamorphopsia was more common in eyes with a greater extent of fingerprint-like microwaves (P = 0.048). The fingerprint sign persisted over a mean follow-up period of 18.0 ± 23.3 without surgery. In 45 eyes that underwent surgery, the extent of fingerprint-like microwaves decreased at 1.2 months (P = 0.001), and further decreased at 13.7 months postoperatively (P = 0.019). However, the proportion of eyes with a fingerprint sign after surgery was similar to that observed preoperatively (P = 0.912).

CONCLUSIONS

Fingerprint-like microwaves were commonly found in eyes with ERM and were associated with ERM severity and BCVA. The microwaves remained long after surgery, although their extent may have decreased after the ERM was resolved. These results suggest that ERM traction may cause long-lasting changes in the HFL.

prominin-1-null Xenopus laevis develop subretinal drusenoid-like deposits, cone-rod dystrophy and RPE atrophy

Prominin-1 (PROM1) variants are associated with inherited, non-syndromic vision loss. We used CRISPR/Cas9 to induce prom1-null mutations in Xenopus laevis and then tracked retinal disease progression from the ages of 6 weeks to 3 years. We found that prom1-null-associated retinal degeneration in frogs was age-dependent and involved retinal pigment epithelium (RPE) dysfunction preceding photoreceptor degeneration. Before photoreceptor degeneration occurred, aging prom1-null frogs developed larger and increasing numbers of cellular debris deposits in the subretinal space and outer segment layer, which resembled subretinal drusenoid deposits (SDDs) in their location, histology and representation as seen by color fundus photography and optical coherence tomography (OCT). Evidence for an RPE origin of these deposits included infiltration of pigment granules into the deposits, thinning of the RPE as measured by OCT, and RPE disorganization as measured by histology and OCT. The appearance and accumulation of SDD-like deposits and RPE thinning and disorganization in our animal model suggests an underlying disease mechanism for prom1-null-mediated blindness that involves death and dysfunction of the RPE preceding photoreceptor degeneration, instead of direct effects upon photoreceptor outer segment morphogenesis, as was previously hypothesized.

Evaluation of inflammatory hyperreflective foci and plasma EPA as diagnostic and predictive markers for age-related macular degeneration

Objectives

To detect the plasma polyunsaturated fatty acids (PUFAs) concentrations in age-related macular degeneration (AMD) patients and healthy controls. Additionally, advanced studies were conducted to investigate the relationship between PUFAs concentrations and ophthalmological characteristics, including hyperreflective foci (HRF), visual acuity, and anti-vascular endothelial growth factor (anti-VEGF) response in patients with AMD.

Methods

This prospective, single-site study recruited a total of 315 participants, consisting of 105 individuals with dry AMD (early-stage AMD group), 105 individuals with neovascular AMD (late-stage AMD group), and 105 elderly individuals without any fundus diseases (healthy controls). The levels of omega-3 and omega-6 PUFAs in plasma were detected using gas chromatography. Retinal thickness, choroidal thickness, and macular volume were quantified using optical coherence tomography angiography (OCTA) scan with a 6 × 6 mm macular area, and the amounts of HRF were analyzed with OCTA scanning data.

Results

Compared to the control group, AMD patients exhibited significantly lower plasma concentrations of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and alpha linolenic acid. HRF were observed in various retinal layers of AMD patients, particularly those with late-stage AMD. The correlation coefficient matrix and multiple linear regression models demonstrated that HRF played a crucial role in best corrected visual acuity for both early (p < 0.001) and late-stage AMD patients (p = 0.006), while EPA had an inverse effect on the logarithm of the minimum angle of resolution (logMAR) value in patients with early-stage AMD (p < 0.001). As compared to patients with good responses to anti-VEGF therapy, those with poor responses had significantly lower baseline logMAR (p < 0.001), central retina thickness (p = 0.002), macular volume (p = 0.027), HRF (p = 0.024), and plasma EPA (p < 0.001). This study used a ROC curve analysis to identify the combination of HRF and EPA as a potential biomarker for predicting the response to anti-VEGF treatment in late-stage AMD patients, with an area under the curve (AUC) value of 0.775.

Conclusions

Reduced plasma EPA was detected in AMD cases and the lower EPA concentration was related to poorer visual acuity. Additionally, the quantity of HRF combined with concentration of plasma EPA may serve as the prognostic indicator for predicting the effect of anti-VEGF treatment in late-stage AMD patients.

A new texture-based labeling framework for hyper-reflective foci identification in retinal optical coherence tomography images

An important abnormality in Optical Coherence Tomography (OCT) images is Hyper-Reflective Foci (HRF). This anomaly can be interpreted as a biomarker of serious retinal diseases such as Age-related Macular Degeneration (AMD) and Diabetic Macular Edema (DME) or the progression of disease from an early stage to a late one. In this paper, a new method is proposed for the identification of HRFs. The new method divides the OCT B-scan into patches and separately verifies each patch to determine whether or not the patch contains an HRF. The procedure of patch verification contains a texture-based framework which assigns appropriate labels according to intensity changes to each column and row. Then, a feature vector is extracted for each patch based on the assigned labels. The feature vectors are utilized in the training step of well-known classifiers like Support Vector Machine (SVM). Then, the classifiers are used to produce the labels for the test OCT images. The new method is evaluated on a public dataset including HRF labels. The experimental results show that the new method is capable of providing outstanding results in terms of speed and accuracy.

Longitudinal Optical Coherence Tomography Imaging Reveals Hyperreflective Foci Characteristics in Relapsing-Remitting Multiple Sclerosis Patients

Background/Objectives: Retinal hyperreflective foci, 25-50 µm in diameter, that can be imaged by noninvasive optical coherence tomography (OCT) may represent microglial activity related to inflammation. This study aimed to detect hyperreflective foci in the OCT-hyporeflective avascular outer nuclear layer of the retina in relapsing-remitting MS (RRMS) patients without ongoing eye or optic nerve disease. Methods: A cohort of 13 RRMS patients (8 eyes with and 18 eyes without prior optic neuritis) underwent retinal OCT at baseline, after 1 month, after 6 months, and then every 6 months for 3 years. The data were compared with single-examination data from 106 eyes in 53 age-matched healthy subjects. Results: The prevalence of hyperreflective foci at baseline was higher in RRMS patients than in healthy subjects (46.2% vs. 1.8%, p < 0.005). Patients with optic neuritis had much more foci than those without (p < 0.001). Hyperreflective foci recurred in 23.1% of RRMS patients, bilaterally in one with prior optic neuritis and unilaterally in two without. Conclusions: Patients with RRMS, notably those with prior optic neuritis, had elevated rates of retinal infiltration in the absence of retinal disease, suggesting that the phenomenon may represent elevated activity of an immune surveillance or housekeeping mechanism rather than retinal disease.

Neuropathological hallmarks in the post-mortem retina of neurodegenerative diseases

The retina is increasingly recognised as a potential source of biomarkers for neurodegenerative diseases. Hallmark protein aggregates in the retinal neuronal tissue could be imaged through light non-invasively. Post-mortem studies have already shown the presence of specific hallmark proteins in Alzheimer's disease, primary tauopathies, synucleinopathies and frontotemporal lobar degeneration. This study aims to assess proteinopathy in a post-mortem cohort with different neurodegenerative diseases and assess the presence of the primary pathology in the retina. Post-mortem eyes were collected in collaboration with the Netherlands Brain Bank from donors with Alzheimer's disease (n = 17), primary tauopathies (n = 8), synucleinopathies (n = 27), frontotemporal lobar degeneration (n = 8), mixed pathology (n = 11), other neurodegenerative diseases (n = 6), and cognitively normal controls (n = 25). Multiple cross sections of the retina and optic nerve tissue were immunostained using antibodies against pTau Ser202/Thr205 (AT8), amyloid-beta (4G8), alpha-synuclein (LB509), pTDP-43 Ser409/410 and p62-lck ligand (p62) and were assessed for the presence of aggregates and inclusions. pTau pathology was observed as a diffuse signal in Alzheimer's disease, primary tauopathies and controls with Alzheimer's disease neuropathological changes. Amyloid-beta was observed in the vessel wall and as cytoplasmic granular deposits in all groups. Alpha-synuclein pathology was observed as Lewy neurites in the retina in synucleinopathies associated with Lewy pathology and as oligodendroglial cytoplasmic inclusions in the optic nerve in multiple system atrophy. Anti-pTDP-43 generally showed typical neuronal cytoplasmic inclusion bodies in cases with frontotemporal lobar degeneration with TDP-43 and also in cases with later stages of limbic-associated TDP-43 encephalopathy. P62 showed inclusion bodies similar to those seen with anti-pTDP-43. Furthermore, pTau and alpha-synuclein pathology were significantly associated with increasing Braak stages for neurofibrillary tangles and Lewy bodies, respectively. Mixed pathology cases in this cohort consisted of cases (n = 6) with high Braak LB stages (> 4) and low or moderate AD pathology, high AD pathology (n = 1, Braak NFT 6, Thal phase 5) with moderate LB pathology, or a combination of low/moderate scores for different pathology scores in the brain (n = 4). There were no cases with advanced co-pathologies. In seven cases with Braak LB ≥ 4, LB pathology was observed in the retina, while tau pathology in the retina in the mixed pathology group (n = 11) could not be observed. From this study, we conclude that the retina reflects the presence of the major hallmark proteins associated with neurodegenerative diseases. Although low or moderate levels of copathology were found in the brains of most cases, the retina primarily manifested protein aggregates associated with the main neurodegenerative disease. These findings indicate that with appropriate retinal imaging techniques, retinal biomarkers have the potential to become highly accurate indicators for diagnosing the major neurodegenerative diseases of the brain.

Evaluation of Anatomical and Tomographic Biomarkers as Predictive Visual Acuity Factors in Eyes with Retinal Vein Occlusion Treated with Dexamethasone Implant

Background: This prospective study evaluated the impact of anatomical and tomographic biomarkers on clinical outcomes of intravitreal dexamethasone implants in patients with macular edema secondary to retinal vein occlusion (RVO). Methods: The study included 46 patients (28 with branch RVO (BRVO) and 18 with central RVO (CRVO)). Best corrected visual acuity (BCVA) significantly improved from a mean baseline of 0.817 ± 0.220 logMAR to 0.663 ± 0.267 logMAR at six months and 0.639 ± 0.321 logMAR at twelve months (p < 0.05). Central retinal thickness (CRT) showed a significant reduction from 666.2 ± 212.2 µm to 471.1 ± 215.6 µm at six months and 467 ± 175.7 µm at twelve months (p < 0.05). No significant differences were found in OCT biomarkers between baseline and follow-ups. Results: The study analysed improvements in visual acuity relative to baseline biomarkers. At six months, ellipsoid zone disruption (EZD) was significant for all subgroups. Disorganization of retinal inner layers (DRIL), external limiting membrane (ELM) disruption, macular ischemia (MI), CRT, and BRVO showed significance for any improvement, while DRIL and ELM were significant for changes greater than 0.3 logMAR (p < 0.05). At twelve months, EZD remained significant for all subgroups. ELM, MI, CRT, and BRVO were significant for any improvement, while MI and BRVO were significant for changes greater than 0.3 logMAR (p < 0.05). Hyperreflective foci were not statistically significant at either time point (p > 0.05). Conclusions: The regression model suggested that MI and CRVO could be negative predictive factors for visual outcomes, while ELM and EZD were associated with BCVA improvement one-year post-treatment.

Spatial Distribution of Hyperreflective Choroidal Foci in the Macula of Normal Eyes

Purpose

To investigate variations in the spatial distribution of hyperreflective foci in the choroid of the macula in normal eyes.

Methods

We included eyes with a normal fundus from patients who had undergone optical coherence tomography angiography, covering a 6-mm × 6-mm area centered on the fovea. The macular area was divided into nine sectors according to the modified Early Treatment of Diabetic Retinopathy Study grid. Hyperreflective choroidal foci (HCF) distribution, choriocapillaris vascular density, and choroidal stromal density were determined on en face images of the choroid in each sector.

Results

We included 35 eyes from 35 participants, with a mean age of 52.7 ± 16.8 years. The mean number and area fraction of HCF at the 5-mm macular area were 35.6 ± 7.8 foci/mm2 and 3.0% ± 0.7%, respectively. The number of HCF in the central circle (50.7 ± 20.9 foci/mm2) was greater than that in the inner (35.1 ± 13.0 foci/mm2) or outer rings (35.6 ± 6.5 foci/mm2) (P < 0.001, P < 0.001, respectively). The area fraction of HCF in the central circle (4.84% ± 3.36%) was greater than that in the inner (2.62% ± 1.17%; P < 0.001) or outer rings (3.12% ± 0.67%; P = 0.004). The HCF distribution did not significantly correlate with the choriocapillaris vascular density or choroidal stromal density in each sector.

Conclusions

HCF were more densely distributed in the macular center than in the pericentral or peripheral macular areas.

Translational Relevance

HCF measurement and spatial distribution could provide additional information for evaluating choroidal stromal characteristics.

Microperimetry and Structural Risk Factors on OCT in Intermediate Age-Related Macular Degeneration

PURPOSE

To determine the relationship between structural biomarkers on OCT that increase the risk of disease progression and microperimetric retinal sensitivity in patients with intermediate age-related macular degeneration (iAMD).

DESIGN

Prospective cross-sectional, observational study.

PARTICIPANTS

Forty-five eyes of 23 patients with iAMD.

METHODS

Patients underwent OCT and microperimetry. OCT scans were evaluated for the risk factors intraretinal hyperreflective foci (HRF), hyporeflectivity within drusenoid lesions (HRDL), subretinal drusenoid deposits, double-layer sign (DLS), and drusen volume. Microperimetric retinal sensitivity was analyzed with a 33-point grid covering the macula. With a novel method of determining what part of the retina corresponded to each microperimetry point, a Voronoi diagram was constructed, dividing the macula in cells consisting of the region nearer to each point than any other. The Voronoi diagram was superimposed on the OCT, making it possible to determine the point-to-point location of the OCT risk factors. Univariable and multivariable linear mixed-effect models were used for analysis.

MAIN OUTCOME MEASURES

Association between microperimetric retinal sensitivity and OCT risk factors at individual measuring points.

RESULTS

One thousand four hundred seventy-nine points of retinal sensitivity and corresponding structural area on OCT were included in this study. Retinal sensitivity was significantly decreased with presence of the OCT risk factors HRF, HRDL, DLS, and drusen volume (all P < 0.001) when analyzed with the univariable linear mixed-effect model. The multivariable model showed a significant decrease of retinal sensitivity with presence of HRF (P < 0.001), DLS (P = 0.025), and greater drusen volume (P < 0.001).

CONCLUSIONS

Presence of HRF, DLS, and greater drusen volume, all of which increase the risk of disease progression, is significantly and independently associated with decreased microperimetric retinal sensitivity in patients with iAMD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

A deep learning approach to hard exudates detection and disorganization of retinal inner layers identification on OCT images

The purpose of the study was to detect Hard Exudates (HE) and classify Disorganization of Retinal Inner Layers (DRIL) implementing a Deep Learning (DL) system on optical coherence tomography (OCT) images of eyes with diabetic macular edema (DME). We collected a dataset composed of 442 OCT images on which we annotated 6847 HE and the presence of DRIL. A complex operational pipeline was defined to implement data cleaning and image transformations, and train two DL models. The state-of-the-art neural network architectures (Yolov7, ConvNeXt, RegNetX) and advanced techniques were exploited to aggregate the results (Ensemble learning, Edge detection) and obtain a final model. The DL approach reached good performance in detecting HE and classifying DRIL. Regarding HE detection the model got an AP@0.5 score equal to 34.4% with Precision of 48.7% and Recall of 43.1%; while for DRIL classification an Accuracy of 91.1% with Sensitivity and Specificity both of 91.1% and AUC and AUPR values equal to 91% were obtained. The P-value was lower than 0.05 and the Kappa coefficient was 0.82. The DL models proved to be able to identify HE and DRIL in eyes with DME with a very good accuracy and all the metrics calculated confirmed the system performance. Our DL approach demonstrated to be a good candidate as a supporting tool for ophthalmologists in OCT images analysis.

Role of MicroRNA in linking diabetic retinal neurodegeneration and vascular degeneration

Diabetic retinopathy is the major cause of blindness in diabetic patients, with limited treatment options that do not always restore optimal vision. Retinal nerve degeneration and vascular degeneration are two primary pathological processes of diabetic retinopathy. The retinal nervous system and vascular cells have a close coupling relationship. The connection between neurodegeneration and vascular degeneration is not yet fully understood. Recent studies have found that microRNA plays a role in regulating diabetic retinal neurovascular degeneration and can help delay the progression of the disease. This article will review how microRNA acts as a bridge connecting diabetic retinal neurodegeneration and vascular degeneration, focusing on the mechanisms of apoptosis, oxidative stress, inflammation, and endothelial factors. The aim is to identify valuable targets for new research and clinical treatment of diabetic retinopathy.

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.

Prominin-1 null Xenopus laevis develop subretinal drusenoid-like deposits, cone-rod dystrophy, and RPE atrophy

Mutations in the PROMININ-1 (PROM1) gene are associated with inherited, non-syndromic vision loss. Here, we used CRISPR/Cas9 to induce truncating prom1-null mutations in Xenopus laevis to create a disease model. We then tracked progression of retinal degeneration in these animals from the ages of 6 weeks to 3 years old. We found that retinal degeneration caused by prom1-null is age-dependent and likely involves death or damage to the retinal pigment epithelium (RPE) that precedes photoreceptor degeneration. As prom1-null frogs age, they develop large cellular debris deposits in the subretinal space and outer segment layer which resemble subretinal drusenoid deposits (SDD) in their location, histology, and representation in color fundus photography and optical coherence tomography (OCT). In older frogs, these SDD-like deposits accumulate in size and number, and they are present before retinal degeneration occurs. Evidence for an RPE origin of these deposits includes infiltration of pigment granules into the deposits, thinning of RPE as measured by OCT, and RPE disorganization as measured by histology and OCT. The appearance and accumulation of SDD-like deposits and RPE thinning and disorganization in our animal model suggests an underlying disease mechanism for prom1-null mediated blindness of death and dysfunction of the RPE preceding photoreceptor degeneration, instead of direct effects upon photoreceptor outer segment morphogenesis, as was previously hypothesized.

Inhibition of oxidative stress-induced epithelial-mesenchymal transition in retinal pigment epithelial cells of age-related macular degeneration model by suppressing ERK activation

INTRODUCTION

Epithelial-mesenchymal transition (EMT) of retinal pigment epithelial (RPE) cells is related to the pathogenesis of various retinopathies including age-related macular degeneration (AMD). Oxidative stress is the major factor that induces degeneration of RPE cells associated with the etiology of AMD.

OBJECTIVES

Sodium iodate (NaIO3) generates intracellular reactive oxygen species (ROS) and is widely used to establish a model of AMD due to the selective induction of retinal degeneration. This study was performed to clarify the effects of multiple NaIO3-stimulated signaling pathways on EMT in RPE cells.

METHODS

The EMT characteristics in NaIO3-treated human ARPE-19 cells and RPE cells of the mouse eyes were analyzed. Multiple oxidative stress-induced modulators were investigated and the effects of pre-treatment with Ca2+ chelator, extracellular signal-related kinase (ERK) inhibitor, or epidermal growth factor receptor (EGFR) inhibitor on NaIO3-induced EMT were determined. The efficacy of post-treatment with ERK inhibitor on the regulation of NaIO3-induced signaling pathways was dissected and its role in retinal thickness and morphology was evaluated by using histological cross-sections and spectral domain optical coherence tomography.

RESULTS

We found that NaIO3 induced EMT in ARPE-19 cells and in RPE cells of the mouse eyes. The intracellular ROS, Ca2+, endoplasmic reticulum (ER) stress marker, phospho-ERK, and phospho-EGFR were increased in NaIO3-stimulated cells. Our results showed that pre-treatment with Ca2+ chelator, ERK inhibitor, or EGFR inhibitor decreased NaIO3-induced EMT, interestingly, the inhibition of ERK displayed the most prominent effect. Furthermore, post-treatment with FR180204, a specific ERK inhibitor, reduced intracellular ROS and Ca2+ levels, downregulated phospho-EGFR and ER stress marker, attenuated EMT of RPE cells, and prevented structural disorder of the retina induced by NaIO3.

CONCLUSIONS

ERK is a crucial regulator of multiple NaIO3-induced signaling pathways that coordinate EMT program in RPE cells. Inhibition of ERK may be a potential therapeutic strategy for the treatment of AMD.

OCT Prognostic Biomarkers for Progression to Late Age-related Macular Degeneration: A Systematic Review and Meta-analysis

TOPIC

To evaluate which OCT prognostic biomarkers best predict the risk of progression from early/intermediate to late age-related macular degeneration (AMD).

CLINICAL RELEVANCE

Among > 100 OCT prognostic biomarkers for AMD, it is unclear which are the most relevant for clinicians and researchers to focus on. This review evaluated which OCT biomarkers confer the greatest magnitude of prediction for progression to late AMD.

METHODS

Study protocol was registered on PROSPERO (CRD42023400166). PubMed and Embase were searched from inception to March 2, 2023, and eligible studies assessed following the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The primary outcome was any quantified risk of progression from treatment-naive early/intermediate AMD to late AMD, including hazard ratios (HRs), odds ratios (ORs), and standardized mean differences (at baseline, between eyes with versus without progression), subgrouped by each OCT biomarker. Further meta-analyses were subgrouped by progression to geographic atrophy or neovascularization.

RESULTS

A total of 114 quantified OCT prognostic biomarkers were identified. With high GRADE certainty of evidence, the greatest magnitudes of prediction to late AMD belonged to: external limiting membrane abnormality (OR, 15.42 [7.63, 31.17]), ellipsoid zone abnormality (OR, 10.8 [4.58, 25.46]), interdigitation zone abnormality (OR, 7.68 [2.57, 23]), concurrent large drusen and reticular pseudodrusen (HR, 6.73 [1.35, 33.65], hyporeflective drusen cores (HR, 2.48 [1.8, 3.4]; OR 1.85 [1.29, 2.66]), intraretinal hyperreflective foci (IHRF; HR, 2.16 [0.92, 5.07]; OR 5.08 [3.26, 7.92]), and large drusen (HR, 2.01 [1.35, 2.99]); OR, 1.98 [1.27, 3.08]). There was greater risk of geographic atrophy for IHRF and hyporeflective drusen cores (P < 0.05), and neovascularization for ellipsoid zone abnormality (P < 0.05). Other OCT biomarkers such as drusenoid pigment epithelium detachment, shallow irregular retinal pigment epithelium elevations, and nascent geographic atrophy exhibited large magnitudes of risk but required further studies for validation.

CONCLUSION

This review synthesizes the 6 most relevant OCT prognostic biomarkers for AMD with greater predictive ability than large drusen alone, for clinicians and researchers to focus on. Further study is required to validate other biomarkers with less than high certainty of evidence, and assess how the copresence of biomarkers may affect risks.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Glucose hypometabolism prompts RAN translation and exacerbates C9orf72-related ALS/FTD phenotypes

The most prevalent genetic cause of both amyotrophic lateral sclerosis and frontotemporal dementia is a (GGGGCC)n nucleotide repeat expansion (NRE) occurring in the first intron of the C9orf72 gene (C9). Brain glucose hypometabolism is consistently observed in C9-NRE carriers, even at pre-symptomatic stages, but its role in disease pathogenesis is unknown. Here, we show alterations in glucose metabolic pathways and ATP levels in the brains of asymptomatic C9-BAC mice. We find that, through activation of the GCN2 kinase, glucose hypometabolism drives the production of dipeptide repeat proteins (DPRs), impairs the survival of C9 patient-derived neurons, and triggers motor dysfunction in C9-BAC mice. We also show that one of the arginine-rich DPRs (PR) could directly contribute to glucose metabolism and metabolic stress by inhibiting glucose uptake in neurons. Our findings provide a potential mechanistic link between energy imbalances and C9-ALS/FTD pathogenesis and suggest a feedforward loop model with potential opportunities for therapeutic intervention.

Intraretinal Hyper-Reflective Foci Are Almost Universally Present and Co-Localize With Intraretinal Fluid in Diabetic Macular Edema

Purpose

In diabetic macular edema (DME), hyper-reflective foci (HRF) has been linked to disease severity and progression. Using an automated approach, we aimed to investigate the baseline distribution of HRF in DME and their co-localization with cystoid intraretinal fluid (IRF).

Methods

Baseline spectral-domain optical coherence tomography (SD-OCT) volume scans (N = 1527) from phase III clinical trials YOSEMITE (NCT03622580) and RHINE (NCT03622593) were segmented using a deep-learning-based algorithm (developed using B-scans from BOULEVARD NCT02699450) to detect HRF. The HRF count and volume were assessed. HRF distributions were analyzed in relation to best-corrected visual acuity (BCVA), central subfield thickness (CST), and IRF volume in quartiles, and Diabetic Retinopathy Severity Scores (DRSS) in groups. Co-localization of HRF with IRF was calculated in the central 3-mm diameter using the en face projection.

Results

HRF were present in most patients (up to 99.7%). Median (interquartile range [IQR]) HRF volume within the 3-mm diameter Early Treatment Diabetic Retinopathy Study ring was 1964.3 (3325.2) pL, and median count was 64.0 (IQR = 96.0). Median HRF volumes were greater with decreasing BCVA (nominal P = 0.0109), and increasing CST (nominal P < 0.0001), IRF (nominal P < 0.0001), and DRSS up to very severe nonproliferative diabetic retinopathy (nominal P < 0.0001). HRF co-localized with IRF in the en face projection.

Conclusions

Using automated HRF segmentation of full SD-OCT volumes, we observed that HRF are a ubiquitous feature in DME and exhibit relationships with BCVA, CST, IRF, and DRSS, supporting a potential link to disease severity. The spatial distribution of HRF closely followed that of IRF.

Electrodiagnostic Biomarkers in Paraneoplastic Retinopathy

OBJECTIVE

Paraneoplastic retinopathy (PNR) is a rapid-onset photoreceptor and post-photoreceptor dysfunction triggered by a cross-reaction between antigens expressed by the underlying tumour and retinal proteins. The present study aims to determine the electrodiagnostic biomarkers that support the diagnosis of PNR and evaluate the effect of treatment.

METHODS

A retrospective observational case-controlled study including 25 patients with suspected PNR, of which 11 patients were diagnosed with PNR. The presence of PNR was confirmed based on clinical examination, supported by colour fundus photography, fundus autofluorescence imaging, optical coherence tomography, fluorescein angiography, retinal vessel oximetry, colour test, full-field electroretinogram (ffERG), on-/off ERG, S-cone ERG, and multifocal ERG (mfERG). The relationships between the clinical symptomatology and the effect of therapy were evaluated.

RESULTS

All PNR patients (Nr: 11) presented with subjective symptoms of newly reported central vision or visual field deterioration. Posterior segment findings showed a severe patchy-like retinal atrophy, attenuation of the retinal vessels, and a waxy optic disc. Optical coherence tomography revealed a discontinued ISe line, and multiple hyperreflective foci. Retinal vessel oxygen saturation was increased. Multifocal ERG revealed reduced central and paracentral responses and ffERG severely attenuated scotopic-, photopic-, on-/off- and S-cone responses. The colour vision test revealed a tritan-tetartan-weakness. Two of the PNR patients underwent rituximab therapy with no further progression and even recovery of electrodiagnostic responses.In 1 nPNR (non-paraneoplastic retinopathy) patient (total Nr: 14) pseudoxanthoma elasticum-related retinopathy was the reason for impaired vision. In 3 of 13 patients with bronchopulmonary cancer a MEK- and FGFR-inhibitor- drug toxicity was the reason for the visual deterioration.

CONCLUSION

Careful investigation for signs of central and/or peripheral visual field deterioration must be performed in the presence of history of a co-existing malignancy. The possibility of PNR should be taken into account. The electrodiagnostic biomarkers, suggested in this study, may help to promptly recognise PNR and also to evaluate the effect of implemented therapy.

Novel Artificial Intelligence-Based Assessment of Imaging Biomarkers in Full-Thickness Macular Holes: Preliminary Data from a Pivotal Trial

Artificial intelligence (AI)- and deep learning (DL)-based systems have shown significant progress in the field of macular disorders, demonstrating high performance in detecting retinal fluid and assessing anatomical changes during disease progression. This study aimed to validate an AI algorithm for identifying and quantifying prognostic factors in visual recovery after macular hole (MH) surgery by analyzing major optical coherence tomography (OCT) biomarkers. This study included 20 patients who underwent vitrectomy for a full-thickness macular hole (FTMH). The mean diameter of the FTMH was measured at 285.36 ± 97.4 μm. The preoperative best-corrected visual acuity (BCVA) was 0.76 ± 0.06 logMAR, improving to 0.38 ± 0.16 postoperatively, with a statistically significant difference (p = 0.001). AI software was utilized to assess biomarkers, such as intraretinal fluid (IRF) and subretinal fluid (SRF) volume, external limiting membrane (ELM) and ellipsoid zone (EZ) integrity, and retinal hyperreflective foci (HRF). The AI analysis showed a significant decrease in IRF volume, from 0.08 ± 0.12 mm3 preoperatively to 0.01 ± 0.01 mm3 postoperatively. ELM interruption improved from 79% ± 18% to 34% ± 37% after surgery (p = 0.006), whereas EZ interruption improved from 80% ± 22% to 40% ± 36% (p = 0.007) postoperatively. Additionally, the study revealed a negative correlation between preoperative IRF volume and postoperative BCVA recovery, suggesting that greater preoperative fluid volumes may hinder visual improvement. The integrity of the ELM and EZ was found to be essential for postoperative visual acuity improvement, with their disruption negatively impacting visual recovery. The study highlights the potential of AI in quantifying OCT biomarkers for managing MHs and improving patient care.

Optical Coherence Tomography Features of Macular Hyperpigmented Lesions without Intraretinal Hyperreflective Foci in Age-Related Macular Degeneration

PURPOSE

To evaluate the optical coherence tomography (OCT) features of hyperpigmented lesions in the absence of intraretinal hyperreflective foci (IHRF) on OCT in eyes with age-related macular degeneration (AMD).

METHODS

We retrospectively analyzed OCT images of eyes with intermediate AMD (iAMD) and macular hyperpigmentation (HP) on color fundus photograph (CFP) but without IHRF on OCT in the corresponding location. The most prominent or definite HP was selected for analysis. The infrared reflectance (IR) image registered with the CFP, and the location corresponding to the HP lesion were defined on the IR image. The location of the HP on the corresponding OCT B-scan was assessed for retinal pigment epithelium (RPE) elevation, acquired vitelliform lesion (AVL), abnormal retinal pigment epithelium + basal lamina (RPE + BL) band reflectivity, RPE + BL band thickening, as well as interdigitation zone (IZ), ellipsoid zone (EZ) and external limiting membrane (ELM) disruption.

RESULTS

49 eyes (39 patients) were included in this study. Forty-six (94%) of the hyperpigmented lesions showed a thickened RPE + BL band. RPE + BL band reflectivity was increased in 37 (76%) of the lesions. RPE + BL band thickening, however, was not correlated with RPE + BL band reflectivity (p-value = 0.31). Either thickening or hyperreflectivity of the RPE + BL band was present in all cases. Twenty (41%) lesions had evidence of ELM disruption, 42 (86%) demonstrated EZ disruption and 48 (98%) had IZ disruption. Five (10%) HPs demonstrated AVL. Among cases with RPE elevation (15 cases, 31%), 10 were classified as drusen, 2 as drusenoid PEDs, and 3 as fibrovascular PEDs.

CONCLUSIONS

Thickening and/or hyperreflectivity of the RPE + BL band commonly correspond to regions of macular hyperpigmentation without IHRF in eyes with iAMD.

Analysis of Cytokine Levels Based on Optical Coherence Tomography Findings in Acute and Chronic Central Serous Chorioretinopathy

Purpose: To investigate the characteristics of optical coherence tomography (OCT) and aqueous humor cytokine differences between acute and chronic central serous chorioretinopathy (CSC) and to evaluate the relevance of these findings.Methods: This was a cross-sectional, observational study. Patients with CSC were divided into acute and chronic groups based on the symptom duration and were compared with normal controls. Best-corrected visual acuity (BCVA), central macular thickness (CMT), subfoveal choroidal thickness (CT), hyperreflective foci (HF), and cytokines including vascular endothelial growth factor (VEGF), interleukin (IL)-6, IL-8, IL-10, interferon-inducible protein-10 (IP-10), and monocyte chemoattractant protein-1 (MCP-1) were used as comparison metrics.Results: A total of 62 patients (62 eyes) with CSC (22 with acute CSC and 40 with chronic CSC) and 35 patients as controls were included in this study. The chronic CSC group had significantly older average ages and worse BCVA than the acute CSC group (both p < 0.05). Both CSC groups showed significant increases in CMT and CT (both p < 0.05). In chronic CSC, the CMT was thinner, with more HF in the neuroretina (p = 0.034). VEGF levels were significantly higher in patients with chronic CSC than in those with acute CSC and controls (p < 0.05). The levels of inflammatory cytokines showed no significant difference between the CSC and control groups. Spearman's correlation analysis showed that the number of HF was positively correlated with disease duration (r = 0.311, p = 0.014), logMAR BCVA (r = 0.487, P < 0.001) and MCP-1 levels (r = 0.256, p = 0.045).Conclusions: Chronicity of CSC could lead to upregulation of VEGF. HF was associated with a more severe visual impairment in CSC patients and had relations with the levels of MCP-1.

Biomarkers for the Progression of Intermediate Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of severe vision loss worldwide, with a global prevalence that is predicted to substantially increase. Identifying early biomarkers indicative of progression risk will improve our ability to assess which patients are at greatest risk of progressing from intermediate AMD (iAMD) to vision-threatening late-stage AMD. This is key to ensuring individualized management and timely intervention before substantial structural damage. Some structural biomarkers suggestive of AMD progression risk are well established, such as changes seen on color fundus photography and more recently optical coherence tomography (drusen volume, pigmentary abnormalities). Emerging biomarkers identified through multimodal imaging, including reticular pseudodrusen, hyperreflective foci, and drusen sub-phenotypes, are being intensively explored as risk factors for progression towards late-stage disease. Other structural biomarkers merit further research, such as ellipsoid zone reflectivity and choriocapillaris flow features. The measures of visual function that best detect change in iAMD and correlate with risk of progression remain under intense investigation, with tests such as dark adaptometry and cone-specific contrast tests being explored. Evidence on blood and plasma markers is preliminary, but there are indications that changes in levels of C-reactive protein and high-density lipoprotein cholesterol may be used to stratify patients and predict risk. With further research, some of these biomarkers may be used to monitor progression. Emerging artificial intelligence methods may help evaluate and validate these biomarkers; however, until we have large and well-curated longitudinal data sets, using artificial intelligence effectively to inform clinical trial design and detect outcomes will remain challenging. This is an exciting area of intense research, and further work is needed to establish the most promising biomarkers for disease progression and their use in clinical care and future trials. Ultimately, a multimodal approach may yield the most accurate means of monitoring and predicting future progression towards vision-threatening, late-stage AMD.

Outer Retinal Hyperreflective Dots: A Potential Imaging Biomarker in Rhegmatogenous Retinal Detachment

PURPOSE

To investigate hyperreflective dots (HRDs) on baseline OCT in rhegmatogenous retinal detachment (RRD).

DESIGN

Retrospective cohort study.

SUBJECTS

Consecutive primary fovea-off RRDs presenting between January 2012 and September 2022.

METHODS

Visual acuity (VA) was obtained at baseline, 3, 6, and 12 months. Baseline foveal OCT scans were graded for the presence of HRDs in the outer retina, morphologic stage of RRD in the parafovea, and foveal photoreceptor integrity (intact, patchy or complete loss of the bacillary layer). Epiretinal membrane (ERM) and cystoid macular edema (CME) were graded after surgery.

MAIN OUTCOME MEASURES

The primary outcome was the proportion of patients in each morphologic stage with HRDs present on OCT and their association with postoperative VA. Secondary outcomes included association with the height of foveal detachment, duration of central vision loss, RRD extent, and development of ERM/CME.

RESULTS

A total of 351 patients were included. The presence of HRDs by morphologic stage of RRD was 0% in stage 1, 4.5% (2/42) in stage 2, 13% (7/54) in stage 3a, 16% (20/126) in stage 3b, 48% (40/83) in stage 4, and 85% (35/41) in stage 5. Hyperreflective dots were associated with increasing stage of RRD (P < 0.001), reduced integrity of foveal photoreceptors (P < 0.001), and reduced postoperative VA at 3, 6, and 12 months (P < 0.001), after excluding visually significant cataracts and adjusting for covariates. There was also a significant association between HRDs and height of foveal detachment, duration of central vision loss, and RRD extent (P < 0.001). Hyperreflective dots were neither associated with postoperative ERM formation nor with its severity (P = 0.27). Nevertheless, they were associated with the occurrence of CME at 3 and 6 months after surgery (P = 0.01; P = 0.006).

CONCLUSIONS

Hyperreflective dots have been hypothesized to consist of intraretinal inflammatory cells. We found that HRDs were significantly associated with the morphologic stage, extent, duration, and height of the RRD before surgery and with reduced VA and CME after surgery. Our results suggest that HRDs are associated with photoreceptor degeneration, as longstanding and extensive RRDs are more likely to present with HRDs. The association of HRDs with CME provides insight into the possible importance of inflammatory processes in RRD before and after surgery.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Changes of optical coherence tomographic hyperreflective foci in rhegmatogenous retinal detachment patients after successful surgery

PURPOSE

To assess the changes of hyperreflective foci (HRF) in rhegmatogenous retinal detachment (RRD) patients after successful reattachment surgery.

METHODS

Twenty-nine macula-off RRD eyes with successful reattachment surgery were retrospectively analyzed. Optical coherence tomography (OCT) was used to image macular regions and measure HRF in outer retina and inner retina at 0.5, 1, 3, 6, 12 months after surgery. The relationships between HRF and photoreceptor layer status, visual outcomes were evaluated.

RESULTS

After retinal reattachment, HRF mainly distributed at the location where external limiting membrane (ELM) or inner and outer segment (IS/OS) line was disrupted. The HRF numbers in outer and inner retina were greater in eyes with discontinuous IS/OS line than eyes with continuous IS/OS line (all p<0.05). In the outer retina,  HRF increased in the initial three months after retinal reattachment, and then decreased gradually after 3 months (p<0.05). The HRF number in the outer retina at postoperative 0.5 months was associated with favorable visual outcomes at 6 and 12 months (r=-0.487,  p =0.025; r=-0.626,  p=0.005, respectively), nevertheless, the HRF number at 3 months was correlated with poor visual results at 6 and 12 months (r=0.441,  p =0.017; r=0.477,  p=0.019, respectively).

CONCLUSION

HRF mainly occurred near the site where ELM or IS/OS line was injured after retinal reattachment. In the outer retina, the number of HRF gradually increased in the first 3 months and then gradually decreased. The early appearance of HRF in the outer retina was associated with a good visual prognosis, while the late appearance may suggest a less favorable visual outcome.

Potential application of foveal structural measurements in treatment decision for retinopathy of prematurity: an OCT-based study

PURPOSE

To investigate foveal changes in infants with ROP not requiring treatment(nROP) and ROP infants needing treatment (tROP) using a handheld SD-OCT device.

METHOD

We performed horizontal SD-OCT scans through the fovea in 156 eyes of 81 infants diagnosed with ROP. Foveal immaturity indices including the presence of inner retinal layers (IRL), absence of foveal outer nuclear layers widening (ONL) and attenuation of hyperreflective outer segment layers (OS), presence and type of cystoid macular edema (CME), epiretinal membrane (ERM), foveal pit depth (FPD), foveal pit width (FPW) and central foveal thickness (CFT) were calculated. The multivariate logistic regression model was used to predict the need for treatment based on OCT measurements.

RESULTS

The shape of the foveolar pit was not significantly different among tROP and nROP groups (P-value = 0.287, Chi-square test). IRL extrusion was incomplete in both tROP and nROP groups (P-value = 0.0.41, Chi-square test). Nevertheless, the presence of thicker IRL was more frequent in the nROP group in comparison with the tROP group (100% vs.64.8%, P-value = 0.001). CME was observed in 29% of eyes in the tROP group and 40% of eyes in the nROP group; however, this difference was not statistically significant (P-value = 0.32, Chi-square test). ERM was detected in 15 (75%) and 84 (65.6%) eyes in the nROP and tROP groups, respectively (P-value = 0.39, Chi-square test). Multivariate logistic regression analyses showed that the need for treatment was significantly associated with gestational age (GA), CFT and FPD (P-values 0.001 and 0.002 respectively).

CONCLUSIONS

This study demonstrated GA, foveal pit depth and the central foveal thickness could accurately predict the need for treatment with sensitivity, specificity, and diagnostic accuracy of 97%, 65% and 91.7% respectively.

Automated evaluation of retinal hyperreflective foci changes in diabetic macular edema patients before and after intravitreal injection

Purpose

Fast and automated reconstruction of retinal hyperreflective foci (HRF) is of great importance for many eye-related disease understanding. In this paper, we introduced a new automated framework, driven by recent advances in deep learning to automatically extract 12 three-dimensional parameters from the segmented hyperreflective foci in optical coherence tomography (OCT).

Methods

Unlike traditional convolutional neural networks, which struggle with long-range feature correlations, we introduce a spatial and channel attention module within the bottleneck layer, integrated into the nnU-Net architecture. Spatial Attention Block aggregates features across spatial locations to capture related features, while Channel Attention Block heightens channel feature contrasts. The proposed model was trained and tested on 162 retinal OCT volumes of patients with diabetic macular edema (DME), yielding robust segmentation outcomes. We further investigate HRF's potential as a biomarker of DME.

Results

Results unveil notable discrepancies in the amount and volume of HRF subtypes. In the whole retinal layer (WR), the mean distance from HRF to the retinal pigmented epithelium was significantly reduced after treatment. In WR, the improvement in central macular thickness resulting from intravitreal injection treatment was positively correlated with the mean distance from HRF subtypes to the fovea.

Conclusion

Our study demonstrates the applicability of OCT for automated quantification of retinal HRF in DME patients, offering an objective, quantitative approach for clinical and research applications.

Hyper-reflective dots in optical coherence tomography imaging and inflammation markers in diabetic retinopathy

The aim of this study is to correlate small dot hyper-reflective foci (HRF) observed in spectral domain optical coherence tomography (SD-OCT) scans of an animal model of hyperglycaemia with focal electroretinography (fERG) response and immunolabelling of retinal markers. The eyes of an animal model of hyperglycaemia showing signs of diabetic retinopathy (DR) were imaged using SD-OCT. Areas showing dot HRF were further evaluated using fERG. Retinal areas enclosing the HRF were dissected and serially sectioned, stained and labelled for glial fibrillary acidic protein (GFAP) and a microglial marker (Iba-1). Small dot HRF were frequently seen in OCT scans in all retinal quadrants in the inner nuclear layer or outer nuclear layer in the DR rat model. Retinal function in the HRF and adjacent areas was reduced compared with normal control rats. Microglial activation was detected by Iba-1 labelling and retinal stress identified by GFAP expression in Müller cells observed in discrete areas around small dot HRF. Small dot HRF seen in OCT images of the retina are associated with a local microglial response. This study provides the first evidence of dot HRF correlating with microglial activation, which may allow clinicians to better evaluate the microglia-mediated inflammatory component of progressive diseases showing HRF.

Segmentation of paracentral acute middle maculopathy lesions in spectral-domain optical coherence tomography images through weakly supervised deep convolutional networks

BACKGROUND AND OBJECTIVES

Spectral-domain optical coherence tomography (SD-OCT) is a valuable tool for non-invasive imaging of the retina, allowing the discovery and visualization of localized lesions, the presence of which is associated with eye diseases. The present study introduces X-Net, a weakly supervised deep-learning framework for automated segmentation of paracentral acute middle maculopathy (PAMM) lesions in retinal SD-OCT images. Despite recent advances in the development of automatic methods for clinical analysis of OCT scans, there remains a scarcity of studies focusing on the automated detection of small retinal focal lesions. Additionally, most existing solutions depend on supervised learning, which can be time-consuming and require extensive image labeling, whereas X-Net offers a solution to these challenges. As far as we can determine, no prior study has addressed the segmentation of PAMM lesions in SD-OCT images.

METHODS

This study leverages 133 SD-OCT retinal images, each containing instances of paracentral acute middle maculopathy lesions. A team of eye experts annotated the PAMM lesions in these images using bounding boxes. Then, labeled data were used to train a U-Net that performs pre-segmentation, producing region labels of pixel-level accuracy. To attain a highly-accurate final segmentation, we introduced X-Net, a novel neural network made up of a master and a slave U-Net. During training, it takes the expert annotated, and pixel-level pre-segment annotated images and employs sophisticated strategies to ensure the highest segmentation accuracy.

RESULTS

The proposed method was rigorously evaluated on clinical retinal images excluded from training and achieved an accuracy of 99% with a high level of similarity between the automatic segmentation and expert annotation, as demonstrated by a mean Intersection-over-Union of 0.8. Alternative methods were tested on the same data. Single-stage neural networks proved insufficient for achieving satisfactory results, confirming that more advanced solutions, such as the proposed method, are necessary. We also found that X-Net using Attention U-net for both the pre-segmentation and X-Net arms for the final segmentation shows comparable performance to the proposed method, suggesting that the proposed approach remains a viable solution even when implemented with variants of the classic U-Net.

CONCLUSIONS

The proposed method exhibits reasonably high performance, validated through quantitative and qualitative evaluations. Medical eye specialists have also verified its validity and accuracy. Thus, it could be a viable tool in the clinical assessment of the retina. Additionally, the demonstrated approach for annotating the training set has proven to be effective in reducing the expert workload.

Macular dynamics and visual acuity prognosis in retinal vein occlusions - ways to connect

Background and Objectives: This study aimed to establish possible connections between macular dynamics, various macular features, and visual acuity prognosis among patients with retinal vein occlusions. Materials and Methods: This study included 85 patients with central retinal vein occlusions (CRVO) and 26 with branch retinal vein occlusions (BRVO). We assessed macular features such as central macular thickness (CMT), foveal intraretinal hemorrhage (IRH), the presence and distribution of hyperreflective foci (HF), ellipsoid zone (EZ) disruption, inner retinal layer disorganization (DRIL), and posterior vitreous detachment (PVD), as well as their dynamics over one year of observation and their impact on final visual acuity prognosis, depending on the type of occlusion. Results: Best corrected visual acuity (BCVA) evolution is statistically significant regarding groups of age and type of occlusion and insignificant regarding gender. The best response to intravitreal treatment, quantified as a decrease in CMT, was registered after the first intravitreal injection. Connecting a decrease in CMT with BCVA improvement, we did not register a statistically significant correlation in the CRVO group, only in BRVO cases. The study results showed that complete PVD plays a significant positive role in decreasing CMT and BCVA improvement in cases of CRVO. Our study revealed that no matter the type of occlusion, the presence of foveal IRH will have a negative impact on the BCVA outcome. Statistically significant differences have been noted only for the evolution of visual acuity in non-ischemic CRVO cases, in correlation with the presence of EZ disruption. Outer retinal layer HF has proved to be a predictive factor for poor visual acuity outcomes. Conclusions: The most important non-imaging predicting factors regarding BCVA after retinal vein occlusions are age and baseline BCVA. CMT's dynamics still establish a weak connection with visual acuity fluctuations. The presence of foveal IRH, outer retinal layer HF, and foveal EZ disruption has a negative impact on visual acuity outcomes. Abbreviations: CRVO = central retinal vein occlusions, BRVO = branch retinal vein occlusions, CMT = central macular thickness, IRH = foveal intraretinal hemorrhage, HF = hyperreflective foci, EZ = ellipsoid zone disruption, DRIL = inner retinal layer disorganization, PVD = posterior vitreous detachment, BCVA = best corrected visual acuity, OCT = optical coherence tomography, BCVA Ti = best corrected visual acuity at first, BCVA Tf = best corrected visual acuity after one year, NR of IVI = number of intravitreal injections, SD = standard deviation, M = male, F = female, CMT Ti = central macular thickness at first, CMT T1 = central macular thickness after first injection, CMT T3 = central macular thickness after 3 injections, CMT Tf = central macular thickness after one year.

Long-lived autoreactive memory CD4+ T cells mediate the sustained retinopathy in chronic autoimmune uveitis

Chronic uveitis comprises heterogeneous clinical entities characterized by sustained and recurrent intraocular inflammation that is believed to be driven by autoimmune responses. The management of chronic uveitis is challenging with the limited availability of efficacious treatments, and the underlying mechanisms mediating disease chronicity remain poorly understood as the majority of experimental data are derived from the acute phase of the disease (the first 2-3 weeks post-induction). Herein, we investigated the key cellular mechanisms underlying chronic intraocular inflammation using our recently established murine model of chronic autoimmune uveitis. We demonstrate unique long-lived CD44hi IL-7R+ IL-15R+ CD4+ memory T cells in both retina and secondary lymphoid organs after 3 months postinduction of autoimmune uveitis. These memory T cells functionally exhibit antigen-specific proliferation and activation in response to retinal peptide stimulation in vitro. Critically, these effector-memory T cells are capable of effectively trafficking to the retina and accumulating in the local tissues secreting both IL-17 and IFN-γ upon adoptively transferred, leading to retinal structural and functional damage. Thus, our data reveal the critical uveitogenic functions of memory CD4+ T cells in sustaining chronic intraocular inflammation, suggesting that memory T cells can be a novel and promising therapeutic target for treating chronic uveitis in future translational studies.