In vivo multimodal retinal imaging of disease-related pigmentary changes in retinal pigment epithelium

The quest for early detection of retinal disease: 3D CycleGAN-based translation of optical coherence tomography into confocal microscopy

Optical coherence tomography (OCT) and confocal microscopy are pivotal in retinal imaging, offering distinct advantages and limitations. In vivo OCT offers rapid, noninvasive imaging but can suffer from clarity issues and motion artifacts, while ex vivo confocal microscopy, providing high-resolution, cellular-detailed color images, is invasive and raises ethical concerns. To bridge the benefits of both modalities, we propose a novel framework based on unsupervised 3D CycleGAN for translating unpaired in vivo OCT to ex vivo confocal microscopy images. This marks the first attempt to exploit the inherent 3D information of OCT and translate it into the rich, detailed color domain of confocal microscopy. We also introduce a unique dataset, OCT2Confocal, comprising mouse OCT and confocal retinal images, facilitating the development of and establishing a benchmark for cross-modal image translation research. Our model has been evaluated both quantitatively and qualitatively, achieving Fréchet inception distance (FID) scores of 0.766 and Kernel Inception Distance (KID) scores as low as 0.153, and leading subjective mean opinion scores (MOS). Our model demonstrated superior image fidelity and quality with limited data over existing methods. Our approach effectively synthesizes color information from 3D confocal images, closely approximating target outcomes and suggesting enhanced potential for diagnostic and monitoring applications in ophthalmology.

Retinal Patterns and the Role of Autofluorescence in Choroideremia

BACKGROUND

Choroideremia is a monogenic inherited retinal dystrophy that manifests in males with night blindness, progressive loss of peripheral vision, and ultimately profound sight loss, commonly by middle age. It is caused by genetic defects of the CHM gene, which result in a deficiency in Rab-escort protein-1, a key element for intracellular trafficking of vesicles, including those carrying melanin. As choroideremia primarily affects the retinal pigment epithelium, fundus autofluorescence, which focuses on the fluorescent properties of pigments within the retina, is an established imaging modality used for the assessment and monitoring of affected patients.

METHODS AND RESULTS

In this manuscript, we demonstrate the use of both short-wavelength blue and near-infrared autofluorescence and how these imaging modalities reveal distinct disease patterns in choroideremia. In addition, we show how these structural measurements relate to retinal functional measures, namely microperimetry, and discuss the potential role of these retinal imaging modalities in clinical practice and research studies. Moreover, we discuss the mechanisms underlying retinal autofluorescence patterns by imaging with a particular focus on melanin pigment.

CONCLUSIONS

This could be of particular significance given the current progress in therapeutic options, including gene replacement therapy.

Tracking Macular Sensitivity and Inner Retinal Thickness in Long-Term Type 1 Diabetes: A Five-Year Prospective Examination in Patients without Diabetic Retinopathy

The aim of the study is to compare macular sensitivity and retinal thickness in patients with long-term type 1 diabetes mellitus (DM1) without diabetic retinopathy (DR) after 5 years of follow-up. Thirty-two eyes from 32 long-term DM1 patients without DR were included. All participants underwent a complete ophthalmological examination, including microperimetry and spectral domain optical coherence tomography (SD-OCT). The data were compared with results from 5 years prior. The mean age of the DM1 patients was 43.19 ± 10.17 years, with a mean disease duration of 29.84 ± 8.98 years and good glycemic control. In 2023, patients exhibited a significantly worse best corrected visual acuity (BCVA) compared to 2018 (p < 0.001). DM1 patients did not show statistically significant changes in macular sensitivity over the 5-year follow-up period. Macular integrity showed significant differences between the two time points (p = 0.045). Retinal thickness showed significant differences, particularly in inner retinal layers (IRL) across most of the ETDRS areas. Long-term DM1 patients without DR lesions showed worsened macular integrity and a lower BCVA in 2023. Additionally, they displayed significant alterations in retinal thicknesses, especially in the IRL, between 2018 and 2023. These findings suggest that even in the absence of visible DR, long-term DM1 patients may experience subclinical retinal changes and functional deterioration over time, highlighting the importance of regular monitoring for the early detection and management of potential complications.

Blue Light-Induced Accelerated Formation of Melanolipofuscin-Like Organelles in Japanese Quail RPE Cells: An Electron Microscopic Study

Purpose

The retinal pigment epithelium (RPE) is a monolayer of epithelial cells essential for photoreceptor function and viability. Quail Coturnix japonica is a convenient experimental animal model for the study of age and pathological retina processes to an accelerated time regime. The three main types of pigment granules present in the RPE are melanin-containing melanosomes, lipofuscin-containing lipofuscin granules, and mixed melanolipofuscin granules containing both melanin and lipofuscin. The purpose of this work was to study the process of melanolipofuscinogenesis during aging and under light exposure.

Methods

We examined melanolipofuscin granules in "macular" areas, the area of the retina containing oxycarotenoids, as a function of the macula in humans, of the quail retina by transmission electron microscopy in young, middle-aged, and old birds, and in middle-aged birds irradiated with blue LED light (450 nm, 4 J/cm2).

Results

It has been shown that during photo-oxidative stress caused by the action of blue light on the quail eye, active fusion of melanosomes and lipofuscin granules occurs with formation of various types, including giant, mixed melanolipofuscin-like granules. Increased accumulation of melanolipofuscin-like granules was also observed in non-irradiated old birds.

Conclusions

It is assumed that the decrease in the number of melanosomes in the RPE during aging and photo-oxidative stress is associated with their fusion with lipofuscin granules and subsequent degradation of melanin by reactive oxygen species formed in melanolipofuscin-like granules. The disappearance of melanin deprives the RPE cells of light-filtering and antioxidant protection, and significantly increases the risk of their oxidative stress.

Non-Neovascular Age-Related Macular Degeneration Assessment: Focus on Optical Coherence Tomography Biomarkers

The imagistic evaluation of non-neovascular age-related macular degeneration (AMD) is crucial for diagnosis, monitoring progression, and guiding management of the disease. Dry AMD, characterized primarily by the presence of drusen and retinal pigment epithelium atrophy, requires detailed visualization of the retinal structure to assess its severity and progression. Several imaging modalities are pivotal in the evaluation of non-neovascular AMD, including optical coherence tomography, fundus autofluorescence, or color fundus photography. In the context of emerging therapies for geographic atrophy, like pegcetacoplan, it is critical to establish the baseline status of the disease, monitor the development and expansion of geographic atrophy, and to evaluate the retina's response to potential treatments in clinical trials. The present review, while initially providing a comprehensive description of the pathophysiology involved in AMD, aims to offer an overview of the imaging modalities employed in the evaluation of non-neovascular AMD. Special emphasis is placed on the assessment of progression biomarkers as discerned through optical coherence tomography. As the landscape of AMD treatment continues to evolve, advanced imaging techniques will remain at the forefront, enabling clinicians to offer the most effective and tailored treatments to their patients.

Multifractal Analysis of Choroidal SDOCT Images in the Detection of Retinitis Pigmentosa

The aim of this paper is to investigate whether a multifractal analysis can be applied to study choroidal blood vessels and help ophthalmologists in the early diagnosis of retinitis pigmentosa (RP). In a case study, we used spectral domain optical coherence tomography (SDOCT), which is a noninvasive and highly sensitive imaging technique of the retina and choroid. The image of a choroidal branching pattern can be regarded as a multifractal. Therefore, we calculated the generalized Renyi point-centered dimensions, which are considered a measure of the inhomogeneity of data, to prove that it increases in patients with RP as compared to those in the control group.

Retinal Pigment Epithelium Pigment Granules: Norms, Age Relations and Pathology

The retinal pigment epithelium (RPE), which ensures the normal functioning of the neural retina, is a pigmented single-cell layer that separates the retina from the Bruch's membrane and the choroid. There are three main types of pigment granules in the RPE cells of the human eye: lipofuscin granules (LG) containing the fluorescent "age pigment" lipofuscin, melanoprotein granules (melanosomes, melanolysosomes) containing the screening pigment melanin and complex melanolipofuscin granules (MLG) containing both types of pigments simultaneously-melanin and lipofuscin. This review examines the functional role of pigment granules in the aging process and in the development of oxidative stress and associated pathologies in RPE cells. The focus is on the process of light-induced oxidative degradation of pigment granules caused by reactive oxygen species. The reasons leading to increased oxidative stress in RPE cells as a result of the oxidative degradation of pigment granules are considered. A mechanism is proposed to explain the phenomenon of age-related decline in melanin content in RPE cells. The essence of the mechanism is that when the lipofuscin part of the melanolipofuscin granule is exposed to light, reactive oxygen species are formed, which destroy the melanin part. As more melanolipofuscin granules are formed with age and the development of degenerative diseases, the melanin in pigmented epithelial cells ultimately disappears.

Proposal of dental demineralization diagnosis with OCT echo based on multiscale entropy analysis

Optical coherence tomography (OCT) has been widely used for the diagnosis of dental demineralization. Most methods rely on extracting optical features from OCT echoes for evaluation or diagnosis. However, due to the diversity of biological samples and the complexity of tissues, the separability and robustness of extracted optical features are inadequate, resulting in a low diagnostic efficiency. Given the widespread utilization of entropy analysis in examining signals from biological tissues, we introduce a dental demineralization diagnosis method using OCT echoes, employing multiscale entropy analysis. Three multiscale entropy analysis methods were used to extract features from the OCT one-dimensional echo signal of normal and demineralized teeth, and a probabilistic neural network (PNN) was used for dental demineralization diagnosis. By comparing diagnostic efficiency, diagnostic speed, and parameter optimization dependency, the multiscale dispersion entropy-PNN (MDE-PNN) method was found to have comprehensive advantages in dental demineralization diagnosis with a diagnostic efficiency of 0.9397. Compared with optical feature-based dental demineralization diagnosis methods, the entropy features-based analysis had better feature separability and higher diagnostic efficiency, and showed its potential in dental demineralization diagnosis with OCT.

Volumetric Reconstruction of a Human Retinal Pigment Epithelial Cell Reveals Specialized Membranes and Polarized Distribution of Organelles

Purpose

Despite the centrality of the retinal pigment epithelium (RPE) in vision and retinopathy our picture of RPE morphology is incomplete. With a volumetric reconstruction of human RPE ultrastructure, we aim to characterize major membranous features including apical processes and their interactions with photoreceptor outer segments, basolateral infoldings, and the distribution of intracellular organelles.

Methods

A parafoveal retinal sample was acquired from a 21-year-old male organ donor. With serial block-face scanning electron microscopy, a tissue volume from the inner-outer segment junction to basal RPE was captured. Surface membranes and complete internal ultrastructure of an individual RPE cell were achieved with a combination of manual and automated segmentation methods.

Results

In one RPE cell, apical processes constitute 69% of the total cell surface area, through a dense network of over 3000 terminal branches. Single processes contact several photoreceptors. Basolateral infoldings facing the choriocapillaris resemble elongated filopodia and comprise 22% of the cell surface area. Membranous tubules and sacs of endoplasmic reticulum represent 20% of the cell body volume. A dense basal layer of mitochondria extends apically to partly overlap electron-dense pigment granules. Pores in the nuclear envelope form a distinct pattern of rows aligned with chromatin.

Conclusions

Specialized membranes at the apical and basal side of the RPE cell body involved in intercellular uptake and transport represent over 90% of the total surface area. Together with the polarized distribution of organelles within the cell body, these findings are relevant for retinal clinical imaging, therapeutic approaches, and disease pathomechanisms.

MRChexNet: Multi-modal bridge and relational learning for thoracic disease recognition in chest X-rays

While diagnosing multiple lesion regions in chest X-ray (CXR) images, radiologists usually apply pathological relationships in medicine before making decisions. Therefore, a comprehensive analysis of labeling relationships in different data modes is essential to improve the recognition performance of the model. However, most automated CXR diagnostic methods that consider pathological relationships treat different data modalities as independent learning objects, ignoring the alignment of pathological relationships among different data modalities. In addition, some methods that use undirected graphs to model pathological relationships ignore the directed information, making it difficult to model all pathological relationships accurately. In this paper, we propose a novel multi-label CXR classification model called MRChexNet that consists of three modules: a representation learning module (RLM), a multi-modal bridge module (MBM) and a pathology graph learning module (PGL). RLM captures specific pathological features at the image level. MBM performs cross-modal alignment of pathology relationships in different data modalities. PGL models directed relationships between disease occurrences as directed graphs. Finally, the designed graph learning block in PGL performs the integrated learning of pathology relationships in different data modalities. We evaluated MRChexNet on two large-scale CXR datasets (ChestX-Ray14 and CheXpert) and achieved state-of-the-art performance. The mean area under the curve (AUC) scores for the 14 pathologies were 0.8503 (ChestX-Ray14) and 0.8649 (CheXpert). MRChexNet effectively aligns pathology relationships in different modalities and learns more detailed correlations between pathologies. It demonstrates high accuracy and generalization compared to competing approaches. MRChexNet can contribute to thoracic disease recognition in CXR.

Aberrant intrinsic functional brain topology in methamphetamine-dependent individuals after six-months of abstinence

Our aim was to explore the aberrant intrinsic functional topology in methamphetamine-dependent individuals after six months of abstinence using resting-state functional magnetic imaging (rs-fMRI). Eleven methamphetamines (MA) abstainers who have abstained for six months and eleven healthy controls (HC) were recruited for rs-fMRI examination. The graph theory and functional connectivity (FC) analysis were employed to investigate the aberrant intrinsic functional brain topology between the two groups at multiple levels. Compared with the HC group, the characteristic shortest path length ($ {L}_{p} $) showed a significant decrease at the global level, while the global efficiency ($ {E}_{glob} $) and local efficiency ($ {E}_{loc} $) showed an increase considerably. After FDR correction, we found significant group differences in nodal degree and nodal efficiency at the regional level in the ventral attentional network (VAN), dorsal attentional network (DAN), somatosensory network (SMN), visual network (VN) and default mode network (DMN). In addition, the NBS method presented the aberrations in edge-based FC, including frontoparietal network (FPN), subcortical network (SCN), VAN, DAN, SMN, VN and DMN. Moreover, the FC of large-scale functional brain networks revealed a decrease within the VN and SCN and between the networks. These findings suggest that some functions, e.g., visual processing skills, object recognition and memory, may not fully recover after six months of withdrawal. This leads to the possibility of relapse behavior when confronted with MA-related cues, which may contribute to explaining the relapse mechanism. We also provide an imaging basis for revealing the neural mechanism of MA-dependency after six months of abstinence.

Elevated ADAR expression is significantly linked to shorter overall survival and immune infiltration in patients with lung adenocarcinoma

To date, few studies have investigated whether the RNA-editing enzymes adenosine deaminases acting on RNA (ADARs) influence RNA functioning in lung adenocarcinoma (LUAD). To investigate the role of ADAR in lung cancer, we leveraged the advantages of The Cancer Genome Atlas (TCGA) database, from which we obtained transcriptome data and clinical information from 539 patients with LUAD. First, we compared ARAR expression levels in LUAD tissues with those in normal lung tissues using paired and unpaired analyses. Next, we evaluated the influence of ADARs on multiple prognostic indicators, including overall survival at 1, 3 and 5 years, as well as disease-specific survival and progression-free interval, in patients with LUAD. We also used Kaplan-Meier survival curves to estimate overall survival and Cox regression analysis to assess covariates associated with prognosis. A nomogram was constructed to validate the impact of the ADARs and clinicopathological factors on patient survival probabilities. The volcano plot and heat map revealed the differentially expressed genes associated with ADARs in LUAD. Finally, we examined ADAR expression versus immune cell infiltration in LUAD using Spearman's analysis. Using the Gene Expression Profiling Interactive Analysis (GEPIA2) database, we identified the top 100 genes most significantly correlated with ADAR expression, constructed a protein-protein interaction network and performed a Gene Ontology/Kyoto Encyclopedia of Genes and Genomes analysis on these genes. Our results demonstrate that ADARs are overexpressed in LUAD and correlated with poor patient prognosis. ADARs markedly increase the infiltration of T central memory, T helper 2 and T helper cells, while reducing the infiltration of immature dendritic, dendritic and mast cells. Most immune response markers, including T cells, tumor-associated macrophages, T cell exhaustion, mast cells, macrophages, monocytes and dendritic cells, are closely correlated with ADAR expression in LUAD.

Understanding the Mechanism of Light-Induced Age-Related Decrease in Melanin Concentration in Retinal Pigment Epithelium Cells

It is known that during the process of aging, there is a significant decrease in the number of melanosomes in the retinal pigment epithelium (RPE) cells in the human eye. Melanosomes act as screening pigments in RPE cells and are fundamentally important for protection against the free radicals generated by light. A loss or change in the quality of melanin in melanosomes can lead to the development of senile pathologies and aggravation in the development of various retinal diseases. We have previously shown that the interaction between melanin melanosomes and superoxide radicals results in oxidative degradation with the formation of water-soluble fluorescent products. In the present study, we show, using fluorescence analysis, HPLC, and mass spectrometry, that visible light irradiation on melanolipofuscin granules isolated from RPE cells in the human eye results in the formation of water-soluble fluorescent products from oxidative degradation of melanin, which was in contrast to lipofuscin granules and melanosomes irradiation. The formation of these products occurs as a result of the oxidative degradation of melanin by superoxide radicals, which are generated by the lipofuscin part of the melanolipofuscin granule. We identified these products both in the composition of melanolipofuscin granules irradiated with visible light and in the composition of melanosomes that were not irradiated but were, instead, oxidized by superoxide radicals. In the melanolipofuscin granules irradiated by visible light, ions that could be associated with melanin oxidative degradation products were identified by applying the principal component analysis of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) data. Degradation of the intact melanosomes by visible light is also possible; however, this requires significantly higher irradiation intensities than for melanolipofuscin granules. It is concluded that the decrease in the concentration of melanin in RPE cells in the human eye with age is due to its oxidative degradation by reactive oxygen species generated by lipofuscin, as part of the melanolipofuscin granules, under the action of light.

Multi-scale feature fusion for pavement crack detection based on Transformer

Automated pavement crack image segmentation presents a significant challenge due to the difficulty in detecting slender cracks on complex pavement backgrounds, as well as the significant impact of lighting conditions. In this paper, we propose a novel approach for automated pavement crack detection using a multi-scale feature fusion network based on the Transformer architecture, leveraging an encoding-decoding structure. In the encoding phase, the Transformer is leveraged as a substitute for the convolution operation, which utilizes global modeling to enhance feature extraction capabilities and address long-distance dependence. Then, dilated convolution is employed to increase the receptive field of the feature map while maintaining resolution, thereby further improving context information acquisition. In the decoding phase, the linear layer is employed to adjust the length of feature sequence output by different encoder block, and the multi-scale feature map is obtained after dimension conversion. Detailed information of cracks can be restored by fusing multi-scale features, thereby improving the accuracy of crack detection. Our proposed method achieves an F1 score of 70.84% on the Crack500 dataset and 84.50% on the DeepCrack dataset, which are improvements of 1.42% and 2.07% over the state-of-the-art method, respectively. The experimental results show that the proposed method has higher detection accuracy, better generalization and better crack detection results can be obtained under both high and low brightness conditions.

Abnormal static and dynamic amplitude of low-frequency fluctuations in multiple brain regions of methamphetamine abstainers

Methamphetamine (meth) addiction is a significant social and public health problem worldwide. The relapse rate of meth abstainers is significantly high, but the underlying physiological mechanisms are unclear. Therefore, in this study, we performed resting-state functional magnetic resonance imaging (rs-fMRI) analysis to detect differences in the spontaneous neural activity between the meth abstainers and the healthy controls, and identify the physiological mechanisms underlying the high relapse rate among the meth abstainers. The fluctuations and time variations in the blood oxygenation level-dependent (BOLD) signal of the local brain activity was analyzed from the pre-processed rs-fMRI data of 11 meth abstainers and 11 healthy controls and estimated the amplitude of low-frequency fluctuations (ALFF) and the dynamic ALFF (dALFF). In comparison with the healthy controls, meth abstainers showed higher ALFF in the anterior central gyrus, posterior central gyrus, trigonal-inferior frontal gyrus, middle temporal gyrus, dorsolateral superior frontal gyrus, and the insula, and reduced ALFF in the paracentral lobule and middle occipital gyrus. Furthermore, the meth abstainers showed significantly reduced dALFF in the supplementary motor area, orbital inferior frontal gyrus, middle frontal gyrus, medial superior frontal gyrus, middle occipital gyrus, insula, middle temporal gyrus, anterior central gyrus, and the cerebellum compared to the healthy controls ($ P < 0.05 $). These data showed abnormal spontaneous neural activity in several brain regions related to the cognitive, executive, and other social functions in the meth abstainers and potentially represent the underlying physiological mechanisms that are responsible for the high relapse rate. In conclusion, a combination of ALFF and dALFF analytical methods can be used to estimate abnormal spontaneous brain activity in the meth abstainers and make a more reasonable explanation for the high relapse rate of meth abstainers.

A comparison of optophysiological biomarkers of photoreceptor stress and phototoxicity in BALB/cJ, B6 (Cg)-Tyrc-2J/J, and C57Bl/6J mouse strains

Ophthalmic imaging instruments, including the confocal scanning laser ophthalmoscope and spectral-domain optical coherence tomography system, originally intended for revealing ocular microstructures in the human eye, have been deployed by vision researchers to evaluate the eyes of numerous small and large animal species for more than two decades. In this study, we have used these two instruments to obtain imaging data sequentially from the retinas of three prominent, widely used experimental mouse models to document changes induced by two contrasting vivarium lighting conditions. Mice studied include albino BALB/cJ and B6(Cg)-Tyrc-2J/J and pigmented C57Bl/6J. Mice were reared under dim light conditions until ~8 weeks of age where they underwent baseline imaging. Following, mice were returned to the dim vivarium or relocated to the top rack cage position in a standard vivarium. Mice were then followed for several months by ocular imaging to catalog the retinal dynamics as a function of long-term dim vs. elevated, standard vivarium lighting exposure levels. Upon exposure to elevated light levels, B6(Cg)-Tyrc-2J/J underwent similar changes as BALB/cJ in regard to photoreceptor outer segment shortening, photoreceptor layer proximal aspect hyperreflective changes, and the development of retinal infoldings and autofluorescent sub-retinal inflammatory monocyte infiltrate. Noteworthy, however, is that infoldings and infiltrate occurred at a slower rate of progression in B6(Cg)-Tyrc-2J/J vs. BALB/cJ. The photoreceptor outer nuclear layer thickness of BALB/cJ degenerated steadily following elevated light onset. In contrast, B6(Cg)-Tyrc-2J/J degeneration was unremarkable for many weeks before experiencing a noticeable change in the rate of degeneration that was concomitant with a plateau and decreasing trend in number of retinal infoldings and monocyte infiltrate. Pathological changes in C57Bl/6J mice were unremarkable for all imaging biomarkers assessed with exception to autofluorescent sub-retinal inflammatory monocyte infiltrate, which showed significant accumulation in dim vs. elevated light exposed mice following ~1 year of observation. These data were evaluated using Spearman's correlation and Predictive Power Score matrices to determine the best imaging optophysiological biomarkers for indicating vivarium light stress and light-induced photoreceptor degeneration. This study suggests that changes in proximal aspect hyperreflectivity, outer segment shortening, retinal infoldings and autofluorescent sub-retinal inflammatory monocyte infiltrate are excellent indicators of light stress and light-induced degeneration in albino B6(Cg)-Tyrc-2J/J and BALB/cJ mouse strains.

Retromode Imaging in Age-Related Macular Degeneration

Background and Objectives: Retromode is a relatively new retinal-imaging technique that is based on the transillumination principle and is obtained with a scanning laser ophthalmoscope that uses light in the infrared spectrum. The laser light penetrates into the deep retinal layers and the choroid. Retromode images are captured with a laterally displaced aperture, and the detector captures only the scattered light. The result is a high-contrast pseudo-three-dimensional image. Age-related macular degeneration (AMD) is a disabling retinal disease. AMD is characterized in its early stage by small and intermediate drusen formation, while the signs of intermediate AMD are large drusen and/or pigmentary abnormalities. Late AMD has two forms, geographic atrophy, which is the advanced form of dry AMD, and wet AMD. Most of the lesions of AMD are located in the outer layers of the retina. This new imaging method can provide a glimpse of the deep retinal layers' topographic changes in a non-invasive, fast, and effective way that can match the other imaging tools available. Materials and Methods: The literature review was performed by searching the PubMed database using the following combination of keywords: retromode imaging and age-related macular degeneration. Relevant images similar to the ones in the literature were identified and used as models. Results: The purpose of this article is to highlight the utility of incorporating retromode imaging into the multimodal evaluation of the retina in patients with AMD and to gather and integrate these findings into a brief but comprehensive paper. Conclusions: Retromode imaging is a good screening, diagnosis, and monitoring tool for patients with AMD.

Longitudinal Optical Coherence Tomography Measurement of Retinal Ganglion Cell and Nerve Fiber Layer to Assess Benign Course in Multiple Sclerosis

A benign form of multiple sclerosis (BMS) is not easily diagnosed, but changes of the retinal ganglion cell layer-inner plexiform layer (GCL-IPL) and retinal nerve fiber layer (RNFL) may be sensitive to the disease. The aim of this study was to use optical coherence tomography (OCT) to investigate longitudinal changes of GCL-IPL and RNFL in BMS. Eighteen patients with BMS and 22 healthy control (HC) subjects were included, with a mean follow-up period of 32.1 months in BMS and 34.3 months in HC. Mean disease duration in BMS was 23.3 years, with 14 patients left untreated. Unilateral optic neuritis (ON) was found in eight patients. Non-ON eyes showed thinner GCL-IPL layer in the BMS group relative to HC (p < 0.001). The thinning rate of GCL-IPL in non-ON BMS, however, was −0.19 ± 0.15 µm/year vs. 0 ± 0.11 µm/year for HC (p = 0.573, age-adjusted). Thinning rate of RNFL in non-ON BMS was −0.2 ± 0.27 µm/year vs. −0.05 ± 0.3 µm/year for HC (p = 0.454, age adjusted). Conclusions: Thinning rate of the GCL-IPL and RNFL in BMS is similar to the healthy population but differs from the thinning rate in relapsing-remitting MS, presenting a non-invasive OCT-based criterion for assessing a benign course in multiple sclerosis.

Retinal Alterations as Potential Biomarkers of Structural Brain Changes in Alzheimer’s Disease Spectrum Patients

Retinal imaging being a potential biomarker for Alzheimer’s disease is gradually attracting the attention of researchers. However, the association between retinal parameters and AD neuroimaging biomarkers, particularly structural changes, is still unclear. In this cross-sectional study, we recruited 25 cognitively impaired (CI) and 21 cognitively normal (CN) individuals. All subjects underwent retinal layer thickness and microvascular measurements with optical coherence tomography angiography (OCTA). Gray matter and white matter (WM) data such as T1-weighted magnetic resonance imaging and diffusion tensor imaging, respectively, were also collected. In addition, hippocampal subfield volumes and WM tract microstructural alterations were investigated as classical AD neuroimaging biomarkers. The microvascular and retinal features and their correlation with brain structural imaging markers were further analyzed. We observed a reduction in vessel density (VD) at the inferior outer (IO) sector (p = 0.049), atrophy in hippocampal subfield volumes, such as the subiculum (p = 0.012), presubiculum (p = 0.015), molecular_layer_HP (p = 0.033), GC-ML-DG (p = 0.043) and whole hippocampus (p = 0.033) in CI patients. Altered microstructural integrity of WM tracts in CI patients was also discovered in the cingulum hippocampal part (CgH). Importantly, we detected significant associations between retinal VD and gray matter volumes of the hippocampal subfield in CI patients. These findings suggested that the retinal microvascular measures acquired by OCTA may be markers for the early prediction of AD-related structural brain changes.

Different Morphology of Branching Neovascular Network in Polypoidal Choroidal Vasculopathy: A Swept-Source Optical Coherence Tomography Angiography Study

Purpose: To evaluate the classification system of branching neovascular network (BNN) morphology in polypoidal choroidal vasculopathy (PCV) patients based on swept-source optical coherence tomography (SS-OCT) and swept-source optical coherence tomography angiography (SS-OCTA), and analyze the morphological features in each group as potential prognostic features. Methods: A total of 32 PCV eyes were included in this retrospective study. SS-OCT and SS-OCTA images of 6 mm × 6 mm centered on the foveal of each eye were analyzed. PCV cases were classified into three types ("trunk", "glomeruli", and "stick" type) based on the morphological features of BNN. OCT and OCTA features were compared among the three groups. The correlation of OCT/OCTA features with visual acuity at 12 months after anti-VEGF treatment was also analyzed. Results: Type 1 group had the largest BNN area and the largest numbers of polypoidal lesions. Type 2 group has the largest pigment epithelial detachment (PED) area, PED volume, subretinal fluid (SRF) area, and SRF volume. Type 3 group had better baseline BCVA, the smallest BNN area, the smallest PED size, and the smallest SRF size. Type 1 was also featured by a clear break on Bruch's membrane which corresponded to the origin of neovascular tissue. BCVA at 12 months was not significantly different among groups. Baseline BCVA and baseline central macular thickness were correlated with the final BCVA. Conclusions: The current classification system based on BNN morphology on SS-OCTA was highly applicable and revealed distinct characteristics in each group. The BNN type was not correlated with BCVA at 12 months after treatment.

Evaluation of the Effect of Duration on Retinal Nerve Fiber Layer Thickness and Choroidal Thickness in Exfoliation Syndrome and Exfoliative Glaucoma

Aims: To compare retinal nerve fiber layer (RNFL) thickness and choroidal thickness in patients with exfoliation syndrome (XFS) and exfoliative glaucoma (XFG) for 1−5 years or 6−10 years compared to healthy volunteers. Methods and Material: Seventy-eight eyes of 78 patients with XFG, 78 eyes of 78 patients with XFS, and 83 eyes of 83 healthy individuals were included in this prospective study. SD-OCT data for choroid thickness and RNFL were recorded. Results: RNFL thickness was statistically significantly lower in eyes with XFG and XFS than in the control group (p < 0.001). Macular choroidal thickness decreased significantly in the XFG group compared to the XFS and control groups (p < 0.001). No significant difference was observed between the XFS and control groups (p > 0.05). In terms of choroidal and RNFL thicknesses by years in XFG and XFS patients, values were lower in the patients diagnosed 6−10 years previously than in those diagnosed 1−5 years previously. However, the difference was not statistically significant (p > 0.05). Conclusions: Thinning of both choroidal and RNLF thickness in XFG and XFS patients may mean that PEX material is an important risk factor for the progression of XFS to XFG. In addition, thinner choroid and RNLF thickness in the 6−10 years groups show the effect of PEX material and the importance of time.

A Feasibility Study for Immediate Histological Assessment of Various Skin Biopsies Using Ex Vivo Confocal Laser Scanning Microscopy

BACKGROUND

Digitally stained ex vivo confocal laser scanning microscopy (CLSM) scans are a possible alternative to formalin-fixed and paraffin-embedded (FFPE) and hematoxylin-eosin (H&E) stained slides. This study explores the diagnostic accuracy of digitally-stained CLSM scans in comparison to H&E-stained slides in various dermatologic diseases in a real-life setting.

METHODS

Samples of patients out of one selected dermatologic office were primarily scanned via CLSM; a diagnosis was made afterwards using FFPE- and H&E-stained slides by two experienced dermatopathologists. Primary outcomes were sensitivity and specificity of diagnosis in digitally stained CLSM scans in three separate diagnostic groups.

RESULTS

CLSM evaluation of epithelial tumors (n = 132) demonstrated a sensitivity of 64.3%/83.9% and a specificity of 84.2%/71.1%. Diagnosis of melanocytic tumors (n = 86) showed a sensitivity of 19.1%/85.1% and a specificity of 96.3%/66.7%. In the diagnosis of other tumors/cysts and inflammatory dermatoses (n = 42), a sensitivity of 96.4%/96.8% and a specificity of 57.1%/45.5% was reached.

CONCLUSIONS

This study shows the possibilities and limitations of a broad use of CLSM. Because of a partly low diagnostic accuracy, such an application does not seem to be recommendable at present for every indication.

Choroidal and Retinal Thicknesses in Type 2 Diabetes Mellitus with Moderate Diabetic Retinopathy Measured by Swept Source OCT

Background: To study choroidal thickness (CT) in type 2 diabetes mellitus (DM2) patients with moderate diabetic retinopathy (DR) and to correlate with changes in retinal thickness (RT) with swept-source OCT (SS-OCT) compared to healthy subjects. Methods: Fifty-four DM2 patients with moderate DR without diabetic macular edema (DME) and 73 age-matched healthy subjects were evaluated using SS-OCT to measure changes in total RT and CT in the nine areas of the Early Treatment Diabetic Retinopathy Study (ETDRS) macular grid. Results: The mean age was 64.06 ± 11.98 years and 60.79 ± 8.62 years in the diabetic and control groups, respectively. Total RT showed statistically significant differences in the temporal inner area, with higher values in the DM2 group (p = 0.010). CT did not show differences between the groups. There was a significant negative correlation between RT and age in all of the outer ETDRS areas and a positive significant correlation in the central area for the DM2 group. There was also a negative significant correlation between CT and age in all of the ETDRS areas except for the inferior inner area. In the DM2 group, a negative correlation was observed between RT and CT in the central area (p = 0.039) and in both horizontal parafoveal areas (temporal inner, p = 0.028; nasal inner, p= 0.003). Conclusion: DM2 patients with moderate DR have no changes with regard to CT. Both CT and RT decreased with age in DM2, showing a negative correlation between these factors in the central and horizontal parafoveal areas of the ETDRS grid.

Transformer with progressive sampling for medical cellular image segmentation

The convolutional neural network, as the backbone network for medical image segmentation, has shown good performance in the past years. However, its drawbacks cannot be ignored, namely, convolutional neural networks focus on local regions and are difficult to model global contextual information. For this reason, transformer, which is used for text processing, was introduced into the field of medical segmentation, and thanks to its expertise in modelling global relationships, the accuracy of medical segmentation was further improved. However, the transformer-based network structure requires a certain training set size to achieve satisfactory segmentation results, and most medical segmentation datasets are small in size. Therefore, in this paper we introduce a gated position-sensitive axial attention mechanism in the self-attention module, so that the transformer-based network structure can also be adapted to the case of small datasets. The common operation of the visual transformer introduced to visual processing when dealing with segmentation tasks is to divide the input image into equal patches of the same size and then perform visual processing on each patch, but this simple division may lead to the destruction of the structure of the original image, and there may be large unimportant regions in the divided grid, causing attention to stay on the uninteresting regions, affecting the segmentation performance. Therefore, in this paper, we add iterative sampling to update the sampling positions, so that the attention stays on the region to be segmented, reducing the interference of irrelevant regions and further improving the segmentation performance. In addition, we introduce the strip convolution module (SCM) and pyramid pooling module (PPM) to capture the global contextual information. The proposed network is evaluated on several datasets and shows some improvement in segmentation accuracy compared to networks of recent years.

Subcellular Comparison of Visible-Light Optical Coherence Tomography and Electron Microscopy in the Mouse Outer Retina

Purpose

We employed in vivo, 1.0-µm axial resolution visible-light optical coherence tomography (OCT) and ex vivo electron microscopy (EM) to investigate three subcellular features in the mouse outer retina: reflectivity oscillations inner to band 1 (study 1); hyperreflective band 2, attributed to the ellipsoid zone or inner segment/outer segment (IS/OS) junction (study 2); and the hyperreflective retinal pigment epithelium (RPE) within band 4 (study 3).

Methods

Pigmented (C57BL/6J, n = 10) and albino (BALB/cJ, n = 3) mice were imaged in vivo. Enucleated eyes were processed for light and electron microscopy. Using well-accepted reference surfaces, we compared micrometer-scale axial reflectivity of visible-light OCT with subcellular organization, as revealed by 9449 annotated EM organelles and features across four pigmented eyes.

Results

In study 1, outer nuclear layer reflectivity peaks coincided with valleys in heterochromatin clump density (-0.34 ± 2.27 µm limits of agreement [LoA]). In study 2, band 2 depth on OCT and IS/OS junction depth on EM agreed (-0.57 ± 0.76 µm LoA), with both having similar distributions. In study 3, RPE electron dense organelle distribution did not agree with reflectivity in C57BL/6J mice, with OCT measures of RPE thickness exceeding those of EM (2.09 ± 0.89 µm LoA). Finally, RPE thickness increased with age in pigmented mice (slope = 0.056 µm/mo; P = 6.8 × 10-7).

Conclusions

Visible-light OCT bands arise from subcellular organization, enabling new measurements in mice. Quantitative OCT-EM comparisons may be confounded by hydration level, particularly in the OS and RPE. Caution is warranted in generalizing results to other species.

In Vivo Imaging of Retinal and Choroidal Morphology and Vascular Plexuses of Vertebrates Using Swept-Source Optical Coherence Tomography

Purpose

To perform in vivo evaluation of the structural morphology and vascular plexuses of the neurosensory retina and choroid across vertebrate species using swept-source optical coherence tomography (SS-OCT) and SS-OCT angiography (SS-OCTA) imaging.

Methods

A custom-built SS-OCT system with an incorporated flexible imaging arm was used to acquire the three-dimensional (3D) retinal OCT and vascular OCTA data of five different vertebrates: a mouse (C57BL/6J), a rat (Long Evans), a gray short-tailed opossum (Monodelphis domestica), a white sturgeon (Acipenser transmontanus), and a great horned owl (Bubo virginianus).

Results

In vivo structural morphology of the retina and choroid, as well as en face OCTA images of retinal and choroidal vasculature of all species were generated. The retinal morphology and vascular plexuses were similar between rat and mouse, whereas distinct choroidal and paired superficial vessels were observed in the opossum retina. The retinal and vascular structure of the sturgeon, as well as the pecten oculi and overlying the avascular and choroidal vasculature in the owl retina are reported in vivo.

Conclusions

A high-quality two-dimensional and 3D in vivo visualization of the retinal structures and en face visualization of the retina and choroidal vascular plexus of vertebrates was possible. Our studies affirm that SS-OCT and SS-OCTA are viable methods for evaluating the in vivo retinal and choroidal structure across terrestrial, aquatic, and aerial vertebrates.

Translational Relevance

In vivo characterization of retinal morphology and vasculature plexus of multiple species using SS-OCT and SS-OCTA imaging can increase the pool of species available as models of human retinal diseases.

A Criterion of Colorectal Cancer Diagnosis Using Exosome Fluorescence-Lifetime Imaging

This study was aimed to investigate the applicability of the exosome fluorescence-lifetime imaging microscopy (FLIM) for colorectal cancer (CRC) diagnosis. Differential ultra-centrifugation was used to extract exosomes from the blood plasma of 11 patients with colon polyps (CPs) and 13 patients with CRC at the T2-4, N0-3, and M0-1 stages. Analysis was performed using a two-photon FLIM device. In total, 165 and 195 FLIM images were recorded for the CP and CCR patient groups, respectively. Two classes of exosomes differentiated by autofluorescence average lifetime tm were discovered in the samples. The first class of exosomes with tm = (0.21 ± 0.06) ns was mostly found in samples from CRC patients. The second class with tm = (0.43 ± 0.19) ns was mostly found in samples from CP patients. The relative number of “CRC-associated” exosomes Nch in the FLIM dataset was shown to be very small for the CP patient group and large for the CRC patient group. This difference was statistically significant. Therefore, the suggested CRS diagnostics criterion can be as follows. If Nch > 0.5, the probability of CRC is high. If Nch < 0.3, the probability of CRC is low.

Using directional OCT to analyze photoreceptor visibility over AMD-related drusen

Investigators have reported reduced visibility of the cone photoreceptors overlying drusen using adaptive optics (AO) imaging techniques. Two hypotheses have been proposed to explain this phenomenon. First, the disease-related deformation of the photoreceptor outer segment (OS) may reduce its ability to act as a wave guide, thus decreasing the cell's familiar reflectance pattern. Second, drusen could disorient the photoreceptors away from the eye's pupil, reducing the amount of light reflected back out the pupil. In this work, we use directional OCT (dOCT) images of drusen in AMD patients to measure the respective contributions of these deforming and disorienting factors.

Combining Optical Coherence Tomography and Fundus Photography to Improve Glaucoma Screening

We aimed to evaluate the accuracy of glaucoma screening using fundus photography combined with optical coherence tomography and determine the agreement between ophthalmologists and ophthalmology residents. We used a comprehensive ophthalmologic examination dataset obtained from 503 cases (1006 eyes). Of the 1006 eyes, 132 had a confirmed glaucoma diagnosis. Overall, 24 doctors, comprising two groups (ophthalmologists and ophthalmology residents, 12 individuals/group), analyzed the data presented in three screening strategies as follows: (1) fundus photography alone, (2) fundus photography + optical coherence tomography, and (3) fundus photography + optical coherence tomography + comprehensive examination. We investigated the diagnostic accuracy (sensitivity and specificity). The respective sensitivity and specificity values for the diagnostic accuracy obtained by 24 doctors, 12 ophthalmologists, and 12 ophthalmology residents were as follows: (1) fundus photography: sensitivity, 55.4%, 55.4%, and 55.4%; specificity, 91.8%, 94.0%, and 89.6%; (2) fundus photography + OCT: sensitivity, 80.0%, 82.3%, and 77.8%; specificity, 91.7%, 92.9%, and 90.6%; and (3) fundus photography + OCT + comprehensive examination: sensitivity 78.4%, 79.8%, and 77.1%; specificity, 92.7%, 94.0%, and 91.3%. The diagnostic accuracy of glaucoma screening significantly increased with optical coherence tomography. Following its addition, ophthalmologists could more effectively improve the diagnostic accuracy than ophthalmology residents. Screening accuracy is improved when optical coherence tomography is added to fundus photography.

Improvement of Retinal Images Affected by Cataracts

Eye fundus images are used in clinical diagnosis for the detection and assessment of retinal disorders. When retinal images are degraded by scattering due to opacities of the eye tissues, the precise detection of abnormalities is complicated depending on the grading of the opacity. This paper presents a concept proof study on the use of the contrast limited adaptive histogram equalization (CLAHE) technique for better visualization of eye fundus images for different levels of blurring due to different stages of cataracts. Processing is performed in three different color spaces: RGB, CIELAB and HSV, with the aim of finding which one better enhances the missed diagnostic features due to blur. The experimental results show that some fundus features not observable by naked eye can be detected in some of the space color processed with the proposed method. In this work, we also develop and provide an online image process, which allows clinicians to tune the default parameters of the algorithm for a better visualization of the characteristics of fundus images. It also allows the choice of a region of interest (ROI) within the images that provide better visualization of some features than those enhanced by the processing of the full picture.

Weakly supervised training for eye fundus lesion segmentation in patients with diabetic retinopathy

OBJECTIVE

Diabetic retinopathy is the leading cause of vision loss in working-age adults. Early screening and diagnosis can help to facilitate subsequent treatment and prevent vision loss. Deep learning has been applied in various fields of medical identification. However, current deep learning-based lesion segmentation techniques rely on a large amount of pixel-level labeled ground truth data, which limits their performance and application. In this work, we present a weakly supervised deep learning framework for eye fundus lesion segmentation in patients with diabetic retinopathy.

METHODS

First, an efficient segmentation algorithm based on grayscale and morphological features is proposed for rapid coarse segmentation of lesions. Then, a deep learning model named Residual-Attention Unet (RAUNet) is proposed for eye fundus lesion segmentation. Finally, a data sample of fundus images with labeled lesions and unlabeled images with coarse segmentation results is jointly used to train RAUNet to broaden the diversity of lesion samples and increase the robustness of the segmentation model.

RESULTS

A dataset containing 582 fundus images with labels verified by doctors, including hemorrhage (HE), microaneurysm (MA), hard exudate (EX) and soft exudate (SE), and 903 images without labels was used to evaluate the model. In ablation test, the proposed RAUNet achieved the highest intersection over union (IOU) on the labeled dataset, and the proposed attention and residual modules both improved the IOU of the UNet benchmark. Using both the images labeled by doctors and the proposed coarse segmentation method, the weakly supervised framework based on RAUNet architecture significantly improved the mean segmentation accuracy by over 7% on the lesions.

SIGNIFICANCE

This study demonstrates that combining unlabeled medical images with coarse segmentation results can effectively improve the robustness of the lesion segmentation model and proposes a practical framework for improving the performance of medical image segmentation given limited labeled data samples.

Pterygium and Ocular Surface Squamous Neoplasia: Optical Biopsy Using a Novel Autofluorescence Multispectral Imaging Technique

In this study, differentiation of pterygium vs. ocular surface squamous neoplasia based on multispectral autofluorescence imaging technique was investigated. Fifty (N = 50) patients with histopathological diagnosis of pterygium (PTG) and/or ocular surface squamous neoplasia (OSSN) were recruited. Fixed unstained biopsy specimens were imaged by multispectral microscopy. Tissue autofluorescence images were obtained with a custom-built fluorescent microscope with 59 spectral channels, each with specific excitation and emission wavelength ranges, suitable for the most abundant tissue fluorophores such as elastin, flavins, porphyrin, and lipofuscin. Images were analyzed using a new classification framework called fused-classification, designed to minimize interpatient variability, as an established support vector machine learning method. Normal, PTG, and OSSN regions were automatically detected and delineated, with accuracy evaluated against expert assessment by a specialist in OSSN pathology. Signals from spectral channels yielding signals from elastin, flavins, porphyrin, and lipofuscin were significantly different between regions classified as normal, PTG, and OSSN (p < 0.01). Differential diagnosis of PTG/OSSN and normal tissue had accuracy, sensitivity, and specificity of 88 ± 6%, 84 ± 10% and 91 ± 6%, respectively. Our automated diagnostic method generated maps of the reasonably well circumscribed normal/PTG and OSSN interface. PTG and OSSN margins identified by our automated analysis were in close agreement with the margins found in the H&E sections. Such a map can be rapidly generated on a real time basis and potentially used for intraoperative assessment.

Two-Photon Vision in Age-Related Macular Degeneration: A Translational Study

The recently introduced term “two-photon vision” relates to the visual perception resulting from a simultaneous absorption of two photons by photoreceptors. In this study, we determined two-photon retinal sensitivity in age-related macular degeneration (AMD) and compared it that in normal aging. Microperimetry was performed with visible (white) light and infrared (IR) light, which was perceived as green in the two-photon stimulation. In total, 45 subjects were included with one (better) eye studied. Furthermore, best-corrected visual acuity (VA) and ocular straylight were assessed. AMD resulted in decreased median (interquartile range) logMAR VA, i.e., 0.15 (0.05; 0.24), which in normal eyes was −0.02 (−0.06; 0.02). The two groups showed comparable straylight levels. Sensitivity to IR light was significantly lower in the AMD group (p < 0.001): 8.3 (7.4, 9.3) dB than in controls 10.7 (9.7, 11.2) dB. AMD also significantly affected visible light sensitivity (p < 0.001): 14.0 (11.0; 15.5) dB vs. 18.0 (16.3; 18.9) dB. Notably, the two-photon approach yielded a lower data spread. In conclusion, AMD considerably impairs retinal sensitivity measured in the single- and two-photon realm. However, two-photon-vision microperimetry may improve the testing accuracy and offer an additional diagnostic parameter (beyond VA measurements) for retinal function assessment.

Retinal Vascularization Abnormalities Studied by Optical Coherence Tomography Angiography (OCTA) in Type 2 Diabetic Patients with Moderate Diabetic Retinopathy

Diabetic retinopathy (DR) is the most severe and frequent retinal vascular disease that causes significant visual loss on a global scale. The purpose of our study was to evaluate retinal vascularization in the superficial capillary plexus (SCP), the deep capillary plexus (DCP) and the choriocapillaris (CC) and changes in the foveal avascular zone (FAZ) by optical tomography angiography (OCTA) in patients with type 2 diabetes mellitus (DM2) with moderate DR but without diabetic macular oedema (DME). Fifty-four eyes of DM2 with moderate DR (level 43 in the ETDRS scale) and without DME and 73 age-matched healthy eyes were evaluated using OCTA with swept-source (SS)-OCT to measure microvascularization changes in SCP, DCP, CC and the FAZ. The mean ages were 64.06 ± 11.98 and 60.79 ± 8.62 years in the DM2 and control groups, respectively. Visual acuity (VA) was lower in the DM2 patients (p = 0.001), OCTA showed changes in the SCP with a significant diminution in the vascular density and the FAZ area was significantly higher compared to healthy controls, with p < 0.001 at the SCP level. The most prevalent anatomical alterations were peripheral disruption in the SCP (83.3%), microaneurysms (MA) in the SCP and in the DCP (79.6% and 79.6%, respectively) and flow changes in the DCP (81.5%). A significant positive correlation was observed between the DM2 duration and the FAZ area in the SCP (0.304 with p = 0.025). A significant negative correlation was also found between age and CC central perfusion (p < 0.001). In summary, a decrease in the vascular density in DM2 patients with moderate DR without DME was observed, especially at the retinal SPC level. Furthermore, it was found that the FAZ was increased in the DM2 group in both retinal plexuses and was greater in the SCP group.

Semi-Automated Quantification of Retinal and Choroidal Biomarkers in Retinal Vascular Diseases: Agreement of Spectral-Domain Optical Coherence Tomography with and without Enhanced Depth Imaging Mode

BACKGROUND

We compared with and without enhanced depth imaging mode (EDI) in semi-automated quantification of retinal and choroidal biomarkers in optical coherence tomography (OCT) in patients with diabetic retinopathy (DR) or retinal vein occlusion (RVO) complicated by macular edema. We chose to study three OCT biomarkers: the numbers of hyperreflective foci (HF), the ellipsoid zone reflectivity ratio (EZR) and the choroidal vascularity index (CVI), all known to be correlated with visual acuity changes or treatment outcomes.

METHODS

In a single examination, one eye of each patient (n = 60; diabetic retinopathy: n = 27, retinal vein occlusion: n = 33) underwent macular 870 nm spectral domain-OCT (SD-OCT) B-scans without and with EDI mode. Semi-automated quantification of HF, EZR and CVI was applied according to preexisting published protocols. Paired Student's t-test or Wilcoxon rank-sum test was used to test for differences in subgroups. Intraclass correlation coefficient (ICC) and Bland-Altman plots were applied to describe the agreement between quantification in EDI and conventional OCT mode. The effect of macular edema on semi-automated quantification was evaluated.

RESULTS

For the entire cohort, quantification of all three biomarkers was not significantly different in SD-OCT scans with and without EDI mode (p > 0.05). ICC was 0.78, 0.90 and 0.80 for HF, EZR and CVI. The presence of macular edema led to significant differences in the quantification of hyperreflective foci (without EDI: 80.00 ± 33.70, with EDI: 92.08 ± 38.11; mean difference: 12.09, p = 0.03), but not in the quantification of EZR and CVI (p > 0.05).

CONCLUSION

Quantification of EZR and CVI was comparable whether or not EDI mode was used. In conclusion, both retinal and choroidal biomarkers can be quantified from one single 870 nm SD-OCT EDI image.