Algorithm for the Measure of Vitreous Hyperreflective Foci in Optical Coherence Tomographic Scans of Patients With Diabetic Macular Edema

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.

Hyper-reflective vitreous spots in central retinal artery occlusion: An unusual finding in two cases

PURPOSE

To present two consecutive cases of Central Retinal Artery Occlusion (CRAO) with unusual Optical Coherence Tomography (OCT) presentation of Hyperreflective Spots (HRS) in the posterior vitreous.

CASE REPORT

The first patient was a 59 years-old male who developed CRAO in the post-operative period after aortic valve replacement. OCT scans revealed the presence of many HRS in the posterior vitreous, remarkably decreased in number at two months follow-up. The second patient was a 74-year-old male who developed CRAO after arterial chemoembolization for recurrent hepatocellular carcinoma. OCT scans showed again the presence of hyperreflective spots in the posterior vitreous and their reduction at two months follow-up with inner retinal atrophy as the final outcome in both cases.

CONCLUSIONS

HRS in the posterior vitreous have been described in inflammatory eye conditions such as uveitis, diabetic macular edema, post cataract surgery, and considered a clinical sign of inflammation. To our knowledge, the combination of CRAO and HRS has not been previously reported. The number of HRS seems to decrease over time, suggesting a role for inflammatory response in the acute stage of CRAO. A similar pathogenic process is known to occur during cerebral ischemia, where the inflammatory response may exacerbate brain injury and post-ischemic damage.

Automated Region of Interest Selection Improves Deep Learning-Based Segmentation of Hyper-Reflective Foci in Optical Coherence Tomography Images

Hyperreflective foci (HRF) have been associated with retinal disease progression and demonstrated as a negative prognostic biomarker for visual function. Automated segmentation of HRF in retinal optical coherence tomography (OCT) scans can be beneficial to identify the formation and movement of the HRF biomarker as a retinal disease progresses and can serve as the first step in understanding the nature and severity of the disease. In this paper, we propose a fully automated deep neural network based HRF segmentation model in OCT images. We enhance the model's performance by using a patch-based strategy that increases the model's compute on the HRF pixels. The patch-based strategy is evaluated against state of the art HRF segmentation pipelines on clinical retinal image data. Our results shows that the patch-based approach demonstrates a high precision score and intersection over union (IOU) using a ResNet34 segmentation model with Binary Cross Entropy loss function. The HRF segmentation pipeline can be used for analyzing HRF biomarkers for different retinopathies.

Non-vasogenic cystoid maculopathies

Besides cystoid macular edema due to a blood-retinal barrier breakdown, another type of macular cystoid spaces referred to as non-vasogenic cystoid maculopathies (NVCM) may be detected on optical coherence tomography but not on fluorescein angiography. Various causes may disrupt retinal cell cohesion or impair retinal pigment epithelium (RPE) and Müller cell functions in the maintenance of retinal dehydration, resulting in cystoid spaces formation. Tractional causes include vitreomacular traction, epiretinal membranes and myopic foveoschisis. Surgical treatment does not always allow cystoid space resorption. In inherited retinal dystrophies, cystoid spaces may be part of the disease as in X-linked retinoschisis or enhanced S-cone syndrome, or occur occasionally as in bestrophinopathies, retinitis pigmentosa and allied diseases, congenital microphthalmia, choroideremia, gyrate atrophy and Bietti crystalline dystrophy. In macular telangiectasia type 2, cystoid spaces and cavitations do not depend on the fluid leakage from telangiectasia. Various causes affecting RPE function may result in NVCM such as chronic central serous chorioretinopathy and paraneoplastic syndromes. Non-exudative age macular degeneration may also be complicated by intraretinal cystoid spaces in the absence of fluorescein leakage. In these diseases, cystoid spaces occur in a context of retinal cell loss. Various causes of optic atrophy, including open-angle glaucoma, result in microcystoid spaces in the inner nuclear layer due to a retrograde transsynaptic degeneration. Lastly, drug toxicity may also induce cystoid maculopathy. Identifying NVCM on multimodal imaging, including fluorescein angiography if needed, allows guiding the diagnosis of the causative disease and choosing adequate treatment when available.

Aggravation of retinal hard exudates after intravitreal anti-vascular endothelial growth factor therapy for cystoid macular edema and the risk factors: a retrospective study

Background/aims

To evaluate retinal hard exudates (HEs) progression in patients with cystoid macular edema (CME) secondary to diabetic retinopathy (DR) or branch retinal vascular occlusion (BRVO) after intravitreal injections of ranibizumab (IVR) treatment and identify the risk factors for the deterioration of HEs.

Methods

This retrospective study enrolled 288 eyes with center-involving CME secondary to DR or BRVO from 288 patients (one eye per patient). All patients were treated with three loading doses of ranibizumab intravitreally at a monthly interval. The morphologic features of HEs were observed, and the HEs areas were quantified using a semi-automatic method at baseline, 1 month after the first dose of IVR and 1 month after the third dose of IVR therapy. HEs progression was defined as having a > =2-grade increase in the HEs severity scale. The best-corrected vision acuity (BCVA) and alterations in HEs areas were compared between DR and BRVO groups. And logistic regression analyses were used to identify the risk factors for HEs exacerbation.

Results

Morphological changes of retinal HEs occurred in all eyes after IVR therapy, although HEs area was not significantly changed in some eyes. DR group has a higher percentage of eyes with progressed HEs area than the BRVO groups (34.9% vs. 21.8%, P = 0.019) 1 month after the first dose of IVR. Both DR and BRVO groups had a decreased percentage of enlarged HEs 1 month after the third injection, but the DR group is still higher than the BRVO group (17.1% vs. 8.4%, P = 0.027). At baseline, there was no correlation between VA and HEs areas. After the first and third doses of IVR, there still was no consistent correlation between HEs severity and change in VA over time. Furthermore, CME with subretinal fluid (SRF) is associated with a higher risk of HEs progression (P = 0.001). Long CME duration and high serum low-density lipoprotein cholesterol (LDL-C) level were identified as risk factors for HEs progression following IVR treatment in both univariable and multivariable regression analyses (Odds ratio (OR) = 1.88, P = 0.012 and OR = 1.14, P = 0.021, respectively).

Conclusions

Alterations in the area of retinal HEs are widely observed after IVR treatment for CME. The eyes with CME secondary to DR have a higher percentage of progressed HEs than the BRVO eyes. DME with SRF, extended duration of CME, and high LDL-C level are potential risk factors of deteriorated HEs after IVR treatment.

Structure and function of the retina of low-density lipoprotein receptor-related protein 5 (Lrp5)-deficient rats

Loss-of-function mutations in the Wnt co-receptor, low-density lipoprotein receptor-related protein 5 (LRP5), result in familial exudative vitreoretinopathy (FEVR), osteoporosis-pseudoglioma syndrome (OPPG), and Norrie disease. CRISPR/Cas9 gene editing was used to produce rat strains deficient in Lrp5. The purpose of this study was to validate this rat model for studies of hypovascular, exudative retinopathies. The retinal vasculature of wildtype and Lrp5 knockout rats was stained with Giffonia simplifolia isolectin B₄ and imaged by fluorescence microscopy. Effects on retinal structure were investigated by histology. The integrity of the blood-retina barrier was analyzed by measurement of permeability to Evans blue dye and staining for claudin-5. Retinas were imaged by fundus photography and SD-OCT, and electroretinograms were recorded. Lrp5 gene deletion led to sparse superficial retinal capillaries and loss of the deep and intermediate plexuses. Autofluorescent exudates were observed and are correlated with increased Evans blue permeability and absence of claudin-5 expression in superficial vessels. OCT images show pathology similar to OCT of humans with FEVR, and retinal thickness is reduced by 50% compared to wild-type rats. Histology and OCT reveal that photoreceptor and outer plexiform layers are absent. The retina failed to demonstrate an ERG response. CRISPR/Cas9 gene-editing produced a predictable rat Lrp5 knockout model with extensive defects in the retinal vascular and neural structure and function. This rat model should be useful for studies of exudative retinal vascular diseases involving the Wnt and norrin pathways.

Analysis of Parainflammation in Chronic Glaucoma Using Vitreous-OCT Imaging

Glaucoma causes blindness due to the progressive death of retinal ganglion cells. The immune response chronically and subclinically mediates a homeostatic role. In current clinical practice, it is impossible to analyse neuroinflammation non-invasively. However, analysis of vitreous images using optical coherence tomography detects the immune response as hyperreflective opacities. This study monitors vitreous parainflammation in two animal models of glaucoma, comparing both healthy controls and sexes over six months. Computational analysis characterizes in vivo the hyperreflective opacities, identified histologically as hyalocyte-like Iba-1+ (microglial marker) cells. Glaucomatous eyes showed greater intensity and number of vitreous opacities as well as dynamic fluctuations in the percentage of activated cells (50–250 microns²) vs. non-activated cells (10–50 microns²), isolated cells (10 microns²) and complexes (>250 microns²). Smaller opacities (isolated cells) showed the highest mean intensity (intracellular machinery), were the most rounded at earlier stages (recruitment) and showed the greatest change in orientation (motility). Study of vitreous parainflammation could be a biomarker of glaucoma onset and progression.

Joint segmentation of multi-class hyper-reflective foci in retinal optical coherence tomography images

Hyper-reflective foci (HRF) refers to the spot-shaped, block-shaped areas with characteristics of high local contrast and high reflectivity, which is mostly observed in retinal optical coherence tomography (OCT) images of patients with fundus diseases. HRF mainly appears hard exudates (HE) and microglia (MG) clinically. Accurate segmentation of HE and MG is essential to alleviate the harm in retinal diseases. However, it is still a challenge to segment HE and MG simultaneously due to similar pathological features, various shapes and location distribution, blurred boundaries, and small morphology dimensions. To tackle these problems, in this paper, we propose a novel global information fusion and dual decoder collaboration-based network (GD-Net), which can segment HE and MG in OCT images jointly. Specifically, to suppress the interference of similar pathological features, a novel global information fusion (GIF) module is proposed, which can aggregate the global semantic information efficiently. To further improve the segmentation performance, we design a dual decoder collaborative workspace (DDCW) to comprehensively utilize the semantic correlation between HE and MG while enhancing the mutual influence on them by feedback alternately. To further optimize GD-Net, we explore a joint loss function which integrates pixel-level with image-level. The dataset of this study comes from patients diagnosed with diabetic macular edema at the department of ophthalmology, University Medical Center Groningen, the Netherlands. Experimental results show that our proposed method performs better than other state-of-the-art methods, which suggests the effectiveness of the proposed method and provides research ideas for medical applications.

Current understanding of the molecular and cellular pathology of diabetic retinopathy

Diabetes mellitus has profound effects on multiple organ systems; however, the loss of vision caused by diabetic retinopathy might be one of the most impactful in a patient's life. The retina is a highly metabolically active tissue that requires a complex interaction of cells, spanning light sensing photoreceptors to neurons that transfer the electrochemical signal to the brain with support by glia and vascular tissue. Neuronal function depends on a complex inter-dependency of retinal cells that includes the formation of a blood-retinal barrier. This dynamic system is negatively affected by diabetes mellitus, which alters normal cell-cell interactions and leads to profound vascular abnormalities, loss of the blood-retinal barrier and impaired neuronal function. Understanding the normal cell signalling interactions and how they are altered by diabetes mellitus has already led to novel therapies that have improved visual outcomes in many patients. Research highlighted in this Review has led to a new understanding of retinal pathophysiology during diabetes mellitus and has uncovered potential new therapeutic avenues to treat this debilitating disease.

Monitoring New Long-Lasting Intravitreal Formulation for Glaucoma with Vitreous Images Using Optical Coherence Tomography

Intravitreal injection is the gold standard therapeutic option for posterior segment pathologies, and long-lasting release is necessary to avoid reinjections. There is no effective intravitreal treatment for glaucoma or other optic neuropathies in daily practice, nor is there a non-invasive method to monitor drug levels in the vitreous. Here we show that a glaucoma treatment combining a hypotensive and neuroprotective intravitreal formulation (IF) of brimonidine–Laponite (BRI/LAP) can be monitored non-invasively using vitreoretinal interface imaging captured with optical coherence tomography (OCT) over 24 weeks of follow-up. Qualitative and quantitative characterisation was achieved by analysing the changes in vitreous (VIT) signal intensity, expressed as a ratio of retinal pigment epithelium (RPE) intensity. Vitreous hyperreflective aggregates mixed in the vitreous and tended to settle on the retinal surface. Relative intensity and aggregate size progressively decreased over 24 weeks in treated rat eyes as the BRI/LAP IF degraded. VIT/RPE relative intensity and total aggregate area correlated with brimonidine levels measured in the eye. The OCT-derived VIT/RPE relative intensity may be a useful and objective marker for non-invasive monitoring of BRI/LAP IF.

Glucose-Regulated Protein 78 in the Aqueous Humor of Patients with Diabetic Macular Edema

PURPOSE

We identified the associations between levels of aqueous glucose-regulated protein 78 (GRP78) and systemic or ocular factors in patients with center-involving diabetic macular edema (CIDME).

METHODS

We measured the aqueous concentrations of GRP78, interleukin- (IL-) 1β, IL-2, IL-8, IL-10, and IL-17, placental growth factor, and vascular endothelial growth factor (VEGF). We explored the associations between aqueous GRP78 levels and those of other aqueous factors, optical coherence tomography (OCT) findings, and systemic parameters in CIDME patients.

RESULTS

In multivariate regression analysis, aqueous GRP78 levels were associated with aqueous VEGF levels (p = 0.007), length of EZ disruption (p = 0.007), length of EZ disruption (p = 0.007), length of EZ disruption (p = 0.007), length of EZ disruption (.

CONCLUSIONS

Aqueous GRP78 levels correlated with VEGF levels in the aqueous humor and EZ disruption on OCT. However, GRP78 levels were not associated with those of inflammatory biomarkers in the aqueous humor or OCT findings. Additionally, GRP78 could not serve as a biomarker to predict short-term prognosis of anti-VEGF agent.

Factors associated with the duration of action of dexamethasone intravitreal implants in diabetic macular edema patients

We designed this study to determine the association between the duration of action of intravitreal dexamethasone implants and aqueous humor biomarkers or optical coherence tomography (OCT) findings of diabetic macular edema (DME) patients. We measured the concentrations of interleukin (IL)-1β, -8, -10, -17; placental growth factor; and vascular endothelial growth factor in the aqueous humor, and identified the number of hyperreflective foci (HF), grades of ellipsoid zone disruptions, and baseline central subfield thicknesses (CSTs) using OCT of patients with DME. The average duration of action of dexamethasone implants was 4.32 ± 1.18 months. In multivariate linear regression analyses, the duration of action was associated with aqueous IL-8 levels and the number of HF (β = -0.016, p = 0.037 and β = -0.073, p = 0.035, respectively). Multivariate logistic regression showed that the number of HF (>10) was significantly associated with a shorter duration (<4 months) of action (odds ratio: 17.17, p = 0.010). The duration of action of intravitreal dexamethasone implants in DME patients was associated with the level of aqueous IL-8 and the number of HF using OCT. Specifically, higher number of HF in the OCT was associated with a shorter duration of action.

Characteristics of diabetic macular edema patients refractory to anti-VEGF treatments and a dexamethasone implant

Purpose

To determine the characteristics of diabetic macular edema (DME) patients refractory to intravitreal bevacizumab (IVB) treatments and an additional dexamethasone implant.

Methods

We classified 119 DME patients according to whether or not they are responsive to 3 consecutive monthly anti-VEGF treatments and/or an additional dexamethasone implant. We compared their concentrations of IL (interleukin)-1β, IL-8, IL-10, IL-17, placental growth factor (PlGF), and vascular endothelial growth factor (VEGF) in the aqueous humor as well as their optical coherence tomography (OCT) findings, and baseline characteristics. We used logistic regression analyses to identify preoperative factors related to refractoriness to treatments.

Results

Of 119 treatment-naïve DME patients, 50 (42.02%) patients showed responsiveness [central subfield thickness (CST) < 300μm] after 3 IVBs, and 59 (49.58%) patients showed responsiveness after an additional dexamethasone implant, but 10 (8.40%) patients showed CST 300 ≥ μm even after both treatments. Refractory DME patients showed significantly higher number of hyperreflective foci (HF) in the OCT and higher average level of aqueous IL-1β at baseline (p<0.001 and p = 0.042, respectively). In the logistic regression analysis, higher number of HF in the OCT was associated with the refractoriness to both treatments (odds ratio [OR]: 7.03, p = 0.007)

Conclusions

Higher number of HF in the OCT at the initial visit was associated with poor responses to IVBs and an additional dexamethasone implant.

Automatic segmentation of hyperreflective foci in OCT images

BACKGROUND AND OBJECTIVE

The leading cause of vision loss in the Western World is Age-related Macular Degeneration (AMD), but together with modern medicines, tracking the number of Hyperreflective Foci (HF) on Optical Coherence Tomography (OCT) images should assist the treatment of patients. Here, we developed a framework based on deep learning for the automatic segmentation of HF in OCT images.

METHODS

We collected OCT images and annotated them, then these images underwent image preprocessing, and feature extraction steps. Using the prepared data we trained different types of Conventional-, Deep- and Convolutional Neural Networks to perform the task of the automatic segmentation of HF.

RESULTS

We evaluated the various Neural Networks, by performing HF segmentation of clinical data belonging to patients, whose data were excluded from the training process. The results suggest that our systems can achieve reasonably high Dice Coefficient values, and they are comparable with (i.e., in most cases above 95%) the similarity between manual annotations performed by different physicians.

CONCLUSION

From the results, it can be concluded that neural networks can be used to accurately segment HF in OCT images. The results are sufficiently accurate for us to incorporate them into the next phase of the research, building a decision support system for everyday clinical practice.

Automated Quantification of Hyperreflective Foci in SD-OCT With Diabetic Retinopathy

The presence of hyperreflective foci (HFs) is related to retinal disease progression, and the quantity has proven to be a prognostic factor of visual and anatomical outcome in various retinal diseases. However, lack of efficient quantitative tools for evaluating the HFs has deprived ophthalmologist of assessing the volume of HFs. For this reason, we propose an automated quantification algorithm to segment and quantify HFs in spectral domain optical coherence tomography (SD-OCT). The proposed algorithm consists of two parallel processes namely: region of interest (ROI) generation and HFs estimation. To generate the ROI, we use morphological reconstruction to obtain the reconstructed image and histogram constructed for data distributions and clustering. In parallel, we estimate the HFs by extracting the extremal regions from the connected regions obtained from a component tree. Finally, both the ROI and the HFs estimation process are merged to obtain the segmented HFs. The proposed algorithm was tested on 40 3D SD-OCT volumes from 40 patients diagnosed with non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR), and diabetic macular edema (DME). The average dice similarity coefficient (DSC) and correlation coefficient (r) are 69.70%, 0.99 for NPDR, 70.31%, 0.99 for PDR, and 71.30%, 0.99 for DME, respectively. The proposed algorithm can provide ophthalmologist with good HFs quantitative information, such as volume, size, and location of the HFs.

Modulation of three key innate immune pathways for the most common retinal degenerative diseases

This review highlights the role of three key immune pathways in the pathophysiology of major retinal degenerative diseases including diabetic retinopathy, age‐related macular degeneration, and rare retinal dystrophies. We first discuss the mechanisms how loss of retinal homeostasis evokes an unbalanced retinal immune reaction involving responses of local microglia and recruited macrophages, activity of the alternative complement system, and inflammasome assembly in the retinal pigment epithelium. Presenting these key mechanisms as complementary targets, we specifically emphasize the concept of immunomodulation as potential treatment strategy to prevent or delay vision loss. Promising molecules are ligands for phagocyte receptors, specific inhibitors of complement activation products, and inflammasome inhibitors. We comprehensively summarize the scientific evidence for this strategy from preclinical animal models, human ocular tissue analyses, and clinical trials evolving in the last few years.

Inhibition of Atypical Protein Kinase C Reduces Inflammation-Induced Retinal Vascular Permeability

Changes in permeability of retinal blood vessels contribute to macular edema and the pathophysiology of numerous ocular diseases, including diabetic retinopathy, retinal vein occlusions, and macular degeneration. Vascular endothelial growth factor (VEGF) induces retinal permeability and macular thickening in these diseases. However, inflammatory agents, such as tumor necrosis factor-α (TNF-α), also may drive vascular permeability, specifically in patients unresponsive to anti-VEGF therapy. Recent evidence suggests VEGF and TNF-α induce permeability through distinct mechanisms; however, both require the activation of atypical protein kinase C (aPKC). We provide evidence, using genetic mouse models and therapeutic intervention with small molecules, that inhibition of aPKC prevented or reduced vascular permeability in animal models of retinal inflammation. Expression of a kinase-dead aPKC transgene, driven by a vascular and hematopoietic restricted promoter, reduced retinal vascular permeability in an ischemia-reperfusion model of retinal injury. This effect was recapitulated with a small-molecule inhibitor of aPKC. Expression of the kinase-dead aPKC transgene dramatically reduced the expression of inflammatory factors and blocked the attraction of inflammatory monocytes and granulocytes after ischemic injury. Coinjection of VEGF with TNF-α was sufficient to induce permeability, edema, and retinal inflammation, and treatment with an aPKC inhibitor prevented VEGF/TNF-α-induced permeability. These data suggest that aPKC contributes to inflammation-driven retinal vascular pathology and may be an attractive target for therapeutic intervention.

Intravitreal pro-inflammatory cytokines in non-obese diabetic mice: Modelling signs of diabetic retinopathy

Diabetic retinopathy is a vascular disease of the retina characterised by hyperglycaemic and inflammatory processes. Most animal models of diabetic retinopathy are hyperglycaemia-only models that do not account for the significant role that inflammation plays in the development of the disease. In the present study, we present data on the establishment of a new animal model of diabetic retinopathy that incorporates both hyperglycaemia and inflammation. We hypothesized that inflammation may trigger and worsen the development of diabetic retinopathy in a hyperglycaemic environment. Pro-inflammatory cytokines, IL-1β and TNF-α, were therefore injected into the vitreous of non-obese diabetic (NOD) mice. CD1 mice were used as same genetic background controls. Fundus and optical coherence tomography images were obtained before (day 0) as well as on days 2 and 7 after intravitreal cytokine injection to assess vessel dilation and beading, retinal and vitreous hyper-reflective foci and retinal thickness. Astrogliosis and microgliosis were assessed using immunohistochemistry. Results showed that intravitreal cytokines induced vessel dilation, beading, severe vitreous hyper-reflective foci, retinal oedema, increased astrogliosis and microglia upregulation in diabetic NOD mice. Intravitreal injection of inflammatory cytokines into the eyes of diabetic mice therefore appears to provide a new model of diabetic retinopathy that could be used for the study of disease progression and treatment strategies.

Evaluation of hyperreflective foci as a prognostic factor of visual outcome in retinal vein occlusion

AIM

To evaluate the potential role of hyperreflective foci (HF) as a prognostic indicator of visual outcome in patients with macular edema (ME) due to retinal vein occlusion (RVO).

METHODS

We retrospectively reviewed 50 eyes of 50 patients with ME due to ischemic central retinal vein occlusion (CRVO), non-ischemic CRVO and branch retinal vein occlusion (BRVO) who were treated with anti-vascular endothelial growth factor (anti-VEGF) at Beijing Tongren Eye Center from January 2013 to July 2016. All patients underwent best-corrected visual acuity (BCVA), spectral domain optical coherence tomography (SD-OCT) at baseline and follow-up. Such factors were evaluated and compared among three groups as baseline and final BCVA, central retinal thickness (CRT), external limiting membrane (ELM) status and the numbers of HF in different position. Multiple linear regression analysis was employed to analyze the relationship between baseline HF and final BCVA. Changes of HF before and after treatment were evaluated too.

RESULTS

Among three groups, HF could be located in each retinal layers, as well as in vitreous cavity. The mean HF in outer retinal layer (ORL) at baseline was 5.29±8.48 in ischemic CRVO with intact ELM, 1.93±2.76 in non-ischemic CRVO, and 1.75±2.05 in BRVO. With disrupted ELM, the mean HF in ORL increased. There was statistically difference of HF in ORL between intact and disrupted ELM. The numbers of HF in ORL were associated with poor visual outcome among three groups. However, HF in inner retinal layer (IRL) and vitreous cavity were not associated with poor visual outcome. Meanwhile, the baseline HF in ORL and vitreous cavity reduced significantly in non-ischemic CRVO and BRVO after anti-VEGF treatment.

CONCLUSION

The numbers of HF in ORL are prognostic factors associated with the final BCVA in patients with ME due to RVO after anti-VEGF treatment.

Macrophage polarization in experimental and clinical choroidal neovascularization

Macrophages play an important role in the development of age-related macular degeneration (AMD). In this study, the spatial and temporal changes and the polarization of macrophages in murine laser-induced choroidal neovascularization (CNV) were investigated, and the polarized M1 and M2 biomarkers in the aqueous humors of neovascular AMD (nAMD) patients were studied. Macrophages, the main infiltrating inflammatory cells in CNV lesions, were evidenced by a significant increase in F4/80 mRNA expression and by the infiltration of F4/80+ cells in the lesions and the vicinity of laser-induced CNV. The mRNA expressions of M1-related markers were dramatically upregulated in the early stage, while the M2-related markers were slightly upregulated in the middle stage and sustained until the late stage. The results of immunostaining showed a similar early-but-transient M1 pattern and a delayed-but-sustained M2 pattern in laser-induced CNV. In addition, a higher M2/M1 ratio was found in both the murine models (Arg-1/iNOS and CCL22/CXCL10) and the aqueous humors of nAMD patients (CCL22/CXCL10) than in the controls. Our results suggested that the dynamic patterns of M1 and M2 were different in both the experimental and clinical CNV. The M2 macrophages were predominant and may play a more important role in the development of CNV.