HDC-Net: A hierarchical dilation convolutional network for retinal vessel segmentation.

The cardinal symptoms of some ophthalmic diseases observed through exceptional retinal blood vessels, such as retinal vein occlusion, diabetic retinopathy, etc. The advanced deep learning models used to obtain morphological and structural information of blood vessels automatically are conducive to the early treatment and initiative prevention of ophthalmic diseases. In our work, we propose a hierarchical dilation convolutional network (HDC-Net) to extract retinal vessels in a pixel-to-pixel manner. It utilizes the hierarchical dilation convolution (HDC) module to capture the fragile retinal blood vessels usually neglected by other methods. An improved residual dual efficient channel attention (RDECA) module can infer more delicate channel information to reinforce the discriminative capability of the model. The structured Dropblock can help our HDC-Net model to solve the network overfitting effectively. From a holistic perspective, the segmentation results obtained by HDC-Net are superior to other deep learning methods on three acknowledged datasets (DRIVE, CHASE-DB1, STARE), the sensitivity, specificity, accuracy, f1-score and AUC score are {0.8252, 0.9829, 0.9692, 0.8239, 0.9871}, {0.8227, 0.9853, 0.9745, 0.8113, 0.9884}, and {0.8369, 0.9866, 0.9751, 0.8385, 0.9913}, respectively. It surpasses most other advanced retinal vessel segmentation models. Qualitative and quantitative analysis demonstrates that HDC-Net can fulfill the task of retinal vessel segmentation efficiently and accurately.

Serum and Macular Carotenoids in Relation to Retinal Vessel Caliber Fifteen Years Later, in the Second Carotenoids in Age-Related Eye Disease Study.

Purpose: We investigated whether dietary carotenoids lutein and zeaxanthin (L/Z) in the serum and macula were associated with central retinal arteriole and venule calibers in a follow-up ancillary study among older women in the Women's Health Initiative. Methods: Among 390 women who participated in Carotenoids in Age-Related Eye Disease Study 2 (CAREDS2) (2016-2019), we investigated associations between serum L/Z at Women's Health Initiative baseline (1994-1998), and macular pigment optical density (MPOD) at CAREDS baseline (2001-2004), with central retinal vessel caliber in CAREDS2. MPOD was measured using heterochromatic flicker photometry (0.5° from the foveal center) in CAREDS baseline and CAREDS2. Vessel calibers were measured from fundus photographs (CAREDS2). We also explored associations in women with stable MPOD (±0.10 optical density units) over 15 years (n = 106), given the long-term increases in MPOD related to diet patterns and supplement use. Associations were investigated using linear modeling. Results: In the full sample (n = 390), higher serum L/Z (tertile 3 vs. 1) was positively associated with arteriole caliber (mean ± SE, 145.0 ± 1.4 µm vs. 140.8 ± 1.4 µm; P = 0.05) and venule caliber (214.6 ± 2.2 µm vs. 207.5 ± 2.2 µm; P = 0.03). MPOD was also associated with wider vessel calibers (tertile 3 vs. 1), but the trend was only statistically significant for venules (144.4 ± 1.4 µm vs. 141.1 ± 1.4 µm [P = 0.12] and 213.3 ± 2.1 µm vs. 206.0 ± 2.1 µm [P = 0.02], respectively.) Most associations were strengthened in women with stable MPOD over 15 years, including between MPOD and arteriole caliber (149.8 ± 2.6 µm vs.135.8 ± 3.0 µm; P = 0.001). Conclusions: Higher L/Z status in serum and retina was associated with larger central retinal vessel calibers. Prospective studies and clinical trials are needed to elucidate whether L/Z supplementation prevents vision loss through increasing blood flow.

An innovative method for screening and evaluating the degree of diabetic retinopathy and drug treatment based on artificial intelligence algorithms.

Current methods of evaluating the degree of diabetic retinopathy are highly subjective and have no quantitative standard. To objectively evaluate the slight changes in tissue structure during the early stage of retinal diseases, a subjective interpretation and qualitative analysis of the pathological sections of retinal HE in diabetic animals is required for screening and evaluating the degree of diabetic retinopathy and drug efficacy. To develop an innovative method for screening and evaluating the degree of diabetic retinopathy and drug treatment based on artificial intelligence algorithms. Based on the change law of the early nerve fiber layer and the ganglion cells, we get disparate characteristics of the microscopic image of diabetes animal retina HE slices. Using image recognition and deep learning methods on these HE slices, we can identify the changes in the ganglion cells and nerve fiber layer for diagnosing early retinopathy and evaluated the therapeutic effect of the potential drugs. We conduct quantitative calculation per unit length of the nerve fiber layer and total area of the nerve fiber layer to identify biology significance of edema. Additionally, we also perform quantitative calculation with the number of unit area ganglion cells to identify the section in biology cell hyperplasia. Finally, we get the significance of quantitative calculation on the unit cell area to identify ganglion cell shriveling in biology. In addition to the evaluation of the disease degree and changes, we also obtained retinal HE sections after different drug interventions and evaluated the therapeutic effect of the drugs. This study presents a novel quantitative method for screening and evaluating of diabetic retinopathy and drug efficacy.

Quantitative analysis of radial peripapillary capillary plexuses in patients with clinically unilateral pseudoexfoliation syndrome.

PURPOSE: The aim of this study was to image the radial peripapillary capillary vessel densities (RPCvds) of the affected eyes and fellow unaffected eyes of individuals with unilateral pseudoexfoliation syndrome (PES) using optical coherence tomography angiography (OCTA) and to compare the RPCvds with those of normal age-matched individuals. METHODS: The eyes were divided into three groups: the pseudoexfoliative material (PXM)-positive eyes of patients with clinically unilateral PES (study eyes), the fellow eyes of the PXM-positive patients (fellow eyes), and the eyes of healthy patients (control eyes). Those patients with glaucomatous findings, including peripapillary hemorrhaging, cupping, notching, focal thinning of the neuroretinal rim, or intraocular pressure readings greater than 21 mmHg, were excluded from the study. The RPCvd (%), peripapillary retinal nerve fiber layer (RNFL) thickness (µm), cup/disc area ratio, rim area (mm2), disc area (mm2), and cup volume (mm3) were automatically calculated via OCTA. RESULTS: This cross-sectional comparative prospective study included 128 eyes of 88 patients: 40 PXM-positive eyes, 40 fellow eyes, and 48 control eyes. The RPCvds and RNFL thicknesses in the peripapillary region were significantly lower in the study eyes than in the fellow eyes and the control eyes (p = 0.011 and p = 0.011, p = 0.009 and p = 0.004, respectively). There were no significant differences between the fellow eyes and the control eyes with regard to the RPCvd and RNFL values in any region (p > 0.05 for all). CONCLUSION: Lower RPCvds could provoke capillary deficiency and deterioration of the perfusion of the optic nerve head in patients with PES.

Comparison of Prediction Models based on Risk Factors and Retinal Characteristics Associated with Recurrence One Year after Ischemic Stroke.

OBJECTIVES: To develop risk estimation models for 1-year ischemic stroke recurrence using clinical risk factors and retinal characteristics. METHODS: From June 2017 to January 2019, 332 patients with first-ever ischemic stroke were enrolled and followed up in the Shenzhen Traditional Chinese Medicine hospital in China. The primary endpoint was defined as fatal or recurrent stroke after 1 year of the index stroke. Clinical risk factors and retinal characteristics were identified by multivariate logistic models. RESULTS: The multivariate logistic model with only clinical risk factors showed that Cerebral Atherosclerosis (OR 1.68, 95%CI: 1.000-2.81), white matter lesions (OR 3.61, 95%CI: 2.18-5.98), and Cardiac disease (OR 1.88, 95%CI: 1.02-3.46) were statistically significantly associated with higher stroke recurrence risk. The sensitivity and specificity of this model were 69.1% and 68.4% respectively. The multivariate logistic model with only retinal characteristics showed that central retinal venule equivalent (OR .34, 95%CI: .14-.83), hemorrhage (OR .6, 95%CI: .41-.88), exudate (OR 1.64, 95%CI: 1.16-2.32), central retinal artery equivalent (OR 2.95, 95%CI: 1.23-7.08), and Aangle (OR 0.8, 95%CI: .61-1.004) were statistically significantly associated with stroke recurrence. The sensitivity and specificity of the model were 62.0% and 64.4% respectively. The multivariate logistic model with both clinical risk factors and retinal characteristics showed that cerebral atherosclerosis (OR 1.74, 95%CI: 1.020-2.981), white matter lesions (OR 3.65, 95%CI: 2.17-6.13), cardiac disease (OR 1.99, 95%CI: 1.06-3.74), hemorrhage (OR .68, 95%CI: .49-.96), exudate (OR 1.65, 95%CI: 1.16-2.36) were independent risk factors of stroke recurrence. The sensitivity and specificity of the model were 72.5% and 70.7% respectively. CONCLUSIONS: Combining the traditional risk factors of stroke with the retinal vessels characteristics to establish the recurrent cerebral infarction prediction model may improve the accuracy of the prediction.

The effect of Shengpuhuang-tang on retinal inflammation in streptozotocin-induced diabetic rats by NF-κB pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Diabetic retinopathy (DR) is a terrible microvascular disorder causing blindness. Retinal inflammation is the early stage in DR, which is believed to play a crucial role in the development of it. Shengpuhuang-tang (ST), a traditional herbal formula, which has effective treatment of fundus bleeding disorder. ST exerts protective effects against DR in rats, but its underlying mechanism of this efficacy remains unknown. Thus, the objective of this study is to examine the mechanism and the efficacy of ST on retinal inflammation in streptozotocin-induced diabetic rats. MATERIALS AND METHODS: The administration of ST was initiated at 4 weeks after diabetes induction and continued for 12 weeks. Retinal vessel permeability was evaluated by using FITC-dextran and Evans blue. Retinal leukostasis was evaluated with FITC-coupled concanavalin A lectin (ConA). Moreover, western blotting was performed to detect TNF-α, ICAM-1 and the relative expression levels of IκBα, IKKß, and p65 in vivo. RESULTS: The results showed that the retinal inflammation in streptozotocin-induced diabetic rats was significantly decreased by ST. ST could decreased the expression levels of TNF-α, ICAM-1 and inhibited the expression of p-IKKß, p-p65 and IκBα. It could also inhibited the nuclear transfer of p65. CONCLUSIONS: In conclusion, these data suggested that ST may have potential treatment strategies against early stage of diabetic retinopathy through NF-κB pathway.

Thiamine transporter 2 is involved in high glucose-induced damage and altered thiamine availability in cell models of diabetic retinopathy.

Thiamine prevents high glucose-induced damage in microvasculature, and progression of retinopathy and nephropathy in diabetic animals. Impaired thiamine availability causes renal damage in diabetic patients. Two single-nucleotide polymorphisms in SLC19A3 locus encoding for thiamine transporter 2 are associated with absent/minimal diabetic retinopathy and nephropathy despite long-term type 1 diabetes. We investigated the involvement of thiamine transporter 1 and thiamine transporter 2, and their transcription factor specificity protein 1, in high glucose-induced damage and altered thiamine availability in cells of the inner blood-retinal barrier. Human endothelial cells, pericytes and Müller cells were exposed to hyperglycaemic-like conditions and/or thiamine deficiency/over-supplementation in single/co-cultures. Expression and localization of thiamine transporter 1, thiamine transporter 2 and transcription factor specificity protein 1 were evaluated together with intracellular thiamine concentration, transketolase activity and permeability to thiamine. The effects of thiamine depletion on cell function (viability, apoptosis and migration) were also addressed. Thiamine transporter 2 and transcription factor specificity protein 1 expression were modulated by hyperglycaemic-like conditions. Transketolase activity, intracellular thiamine and permeability to thiamine were decreased in cells cultured in thiamine deficiency, and in pericytes in hyperglycaemic-like conditions. Thiamine depletion reduced cell viability and proliferation, while thiamine over-supplementation compensated for thiamine transporter 2 reduction by restoring thiamine uptake and transketolase activity. High glucose and reduced thiamine determine impairment in thiamine transport inside retinal cells and through the inner blood-retinal barrier. Thiamine transporter 2 modulation in our cell models suggests its major role in thiamine transport in retinal cells and its involvement in high glucose-induced damage and impaired thiamine availability.

A Pilot Optical Coherence Tomography Angiography Study on Superficial and Deep Capillary Plexus Foveal Avascular Zone in Patients With Beta-Thalassemia Major.

Purpose: To investigate foveal avascular zone (FAZ) changes in the superficial (SCP) and deep (DCP) capillary plexuses in beta-thalassemia major (BTM) patients, as shown in optical coherence tomography angiography. Methods: Nonrandomized, comparative case series of 54 eyes of 27 BTM patients and 46 eyes of 23 healthy controls, utilizing an automated FAZ detection algorithm. Measurements included FAZ area and FAZ shape descriptors (convexity, circularity, and contour temperature). Results were compared between the two groups, and correlated to iron load and chelation therapy parameters. Results: SCP and DCP FAZ area were not significantly different between the control and BTM groups (P = 0.778 and P = 0.408, respectively). The same was true regarding SCP FAZ convexity (P = 0.946), circularity (P = 0.838), and contour temperature (P = 0.907). In contrast, a statistically significant difference was detected between controls and BTM group regarding DCP FAZ convexity (P = 0.013), circularity (P = 0.010), and contour temperature (P = 0.014). Desferrioxamine dosage was strongly correlated to the DCP area (r = 0.650, P = 0.05) and liver magnetic resonance imaging/T2-star to DCP circularity (r = -0.492, P = 0.038). Correlations were also revealed between urine Fe excretion and DCP convexity (r = 0.531, P = 0.019), circularity (r = 0.661, P = 0.002), and contour temperature (r = -0.591, P = 0.008). Conclusions: Retinal capillary plexuses and especially DCP seem to present unique morphologic changes in BTM patients, not in the FAZ area, but in specific shape descriptors, indicating minor but detectable FAZ changes. These changes correlate well with iron load and chelation therapy parameters. Their clinical importance and pathophysiologic implications remain to be elucidated through further studies.

Management of Deep Retinal Capillary Ischemia by Electromagnetic Stimulation and Platelet-Rich Plasma: Preliminary Clinical Results.

INTRODUCTION: To investigate the efficacy of retinal electromagnetic stimulation and sub-tenon autologous platelet-rich plasma in the treatment of deep retinal capillary ischemia. METHODS: The study included 28 eyes of 17 patients aged 15-76 years (mean 37.9 years) who had deep retinal capillary ischemia. Patients who had acute-onset paracentral scotoma in the last 1 month were included in the study between January 2018 and January 2019. The diagnosis of deep retinal capillary ischemia was based on clinical history and typical findings of optical coherence tomography angiography. The eyes were divided into three groups: group 1 (n = 7 eyes) received electromagnetic stimulation alone; group 2 (n = 7 eyes) received electromagnetic stimulation and sub-tenon autologous platelet-rich plasma injection; group 3 had no intervention and served as a control group (n = 14 eyes). The patients underwent ten sessions of electromagnetic stimulation in groups 1 and 2. Sub-tenon autologous platelet-rich plasma injection was performed immediately after the first, fifth, and tenth sessions of electromagnetic stimulation in group 2. The deep retinal capillary density and best corrected visual acuity changes were investigated before and after treatment at the first month. RESULTS: The mean deep retinal capillary density was 52.0% before electromagnetic stimulation and 56.1% after ten sessions of application in group 1; this improvement was statistically significant (p = 0.01). In the combined treatment group (group 2), the mean deep retinal capillary density was 46.9% before the treatment and 56.5% after the treatment; this increase was also statistically significant (p = 0.01). Statistically significant best corrected visual acuity improvement (p = 0.01) could be achieved only in group 2. The combined treatment was significantly superior (p < 0.01) to treatment with only electromagnetic stimulation regarding best corrected visual acuity and deep retinal capillary density. In the control group (group 3), there was no statistically significant change (p = 0.09) in the mean deep retinal capillary density and best corrected visual acuity. CONCLUSION: Treatment of the underlying cause is a priority in the treatment of deep retinal capillary ischemia. However, in the acute period, local ischemia treatment is necessary to prevent permanent retinal damage and scotomas. In mild cases, only electromagnetic stimulation, which is non-invasive and easy to use, might have a beneficial effect on deep retinal capillary density. In more severe cases, sub-tenon fresh autologous platelet-rich plasma injection together with electromagnetic stimulation may be more effective in the treatment of local ischemia of the retina in order to augment the response. FUNDING: The Rapid Service Fees were funded by the Ankara University Tecnopolis Institute. CLINICAL TRIAL REGISTRATION: titck.gov.tr identifier, 2018-136.

Folate/Vitamin B Alleviates Hyperhomocysteinemia-Induced Alzheimer-Like Pathologies in Rat Retina.

Hyperhomocysteinemia (Hhcy) is an independent risk factor for Alzheimer's disease (AD). Visual dysfunction is commonly found and is positively correlated with the severity of cognitive defects in AD patients. Our previous study demonstrated that Hhcy induces memory deficits with AD-like tau and amyloid-ß (Aß) pathologies in the hippocampus, and supplementation with folate and vitamin B12 (FB) prevents the Hhcy-induced AD-like pathologies in the hippocampus. Here, we investigated whether Hhcy also induces AD-like pathologies in the retina and the effects of FB. An Hhcy rat model was produced by vena caudalis injection of homocysteine for 14 days, and the effects of FB were assessed by simultaneous supplementation with FB in drinking water. We found that Hhcy induced vessel damage with Aß and tau pathologies in the retina, while simultaneous supplementation with FB remarkably attenuated the Hhcy-induced tau hyperphosphorylation at multiple AD-related sites and Aß accumulation in the retina. The mechanisms involved downregulation of amyloid precursor protein (APP), presenilin-1, beta-site APP-cleaving enzyme 1, and protein phosphatase-2A. Our data suggest that the retina may serve as a window for evaluating the effects of FB on hyperhomocysteinemia-induced Alzheimer-like pathologies.

Chebulagic acid and Chebulinic acid inhibit TGF-ß1 induced fibrotic changes in the chorio-retinal endothelial cells by inhibiting ERK phosphorylation.

PURPOSE: Diabetic retinopathy (DR) is characterized by pro-inflammatory, pro-angiogenic and pro-fibrotic environment during the various stages of the disease progression. Basement membrane changes in the retina and formation of fibrovascular membrane are characteristically seen in DR. In the present study the effect of Alcoholic (AlE) extracts of Triphala an ayurvedic herbal formulation and its chief compounds, Chebulagic (CA), Chebulinic (CI) and Gallic acid (GA) were evaluated for TGFß1-induced anti-fibrotic activity in choroid-retinal endothelial cells (RF/6A). METHOD: RF/6A cells were treated with TGFß1 alone or co-treated with AlE, CA, CI or GA. The mRNA and protein expression of fibrotic markers (αSMA, CTGF) were assessed by qPCR and western blot/ELISA. Functional changes were assessed using proliferation assay and migration assay. To deduce the mechanism of action, downstream signaling was assessed by western blot analysis along with in silico docking studies. RESULT: AlE (50 µg/ml) CA and CI at 10 µM reduced the expression of pro-fibrotic genes (αSMA and CTGF) induced by TGFß1, by inhibiting ERK phosphorylation. GA did not inhibit TGFß1 mediated changes in RF/6A cells. In silico experiments shows that CA and CI has favourable binding energy to bind with TGFß receptor and inhibit the downstream signaling, while GA did not. CONCLUSION: Hence this study identifies Triphala and its chief compounds CA and CI as potential adjuvants in the management of DR.

Microvascular Features of Treated Retinoblastoma Tumors in Children Assessed Using OCTA.

BACKGROUND AND OBJECTIVE: To describe the microvascular features of treated, clinically regressed, or reactivated retinoblastoma lesions using an investigational portable optical coherence tomography angiography (OCTA) system. PATIENTS AND METHODS: Single-center, prospective, cross-sectional, consecutive case-series of children with previously treated retinoblastoma who underwent portable OCTA of posterior retinoblastoma lesions. RESULTS: Eight tumors from seven eyes of five children with retinoblastoma were included. Tumors with types 1 (calcified remnant, n = 3), 2 (non-calcified remnant, n = 1), and 3 (both calcified and noncalcified remnants, n = 1) regression revealed persistent intrinsic superficial vasculature on OCTA (five of five lesions; 100%). Lesions with type 4 regression (atrophic scar, n = 2) had complete vascular flow voids in the involved retina and underlying choriocapillaris. A reactivated tumor (n = 1) showed a distinct area of vascularity with prominent feeder/draining vessels. CONCLUSIONS: OCTA revealed that significant vascularity exists in inactive retinoblastoma lesions. Dilated feeder vessels may suggest continued disease activity. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:43-49.].

Chebulagic acid Chebulinic acid and Gallic acid, the active principles of Triphala, inhibit TNFα induced pro-angiogenic and pro-inflammatory activities in retinal capillary endothelial cells by inhibiting p38, ERK and NFkB phosphorylation.

Tumor necrosis factor-α (TNFα) a pleiotropic cytokine induces pro-inflammatory and pro-angiogenic changes in conditions such as diabetic retinopathy (DR) and neovascular age related macular degeneration (NV-AMD). Hence, inhibition of TNFα mediated changes can benefit the management of DR and NV-AMD. Triphala, an ayurvedic herbal preparation is known to have immunomodulatry functions. In this study we evaluated the alcoholic extract of triphala (AlE) and its compounds Chebulagic acid (CA), Chebulinic acid (CI) and Gallic acid (GA) for their anti-TNFα activity. TNFα induced pro-inflammatory and pro-angiogenic changes in the retinal-choroid microvascular endothelial cells (RF/6A). Treatment with CA/CI/GA and the whole Triphala extract showed characteristic inhibition of MMP-9, cell proliferation/migration and tube formation as well the expression of IL-6, IL-8 and MCP-1 without affecting cell viability. This was mediated by inhibition of p38, ERK and NFκB phosphorylation. Ex vivo angiogenesis assay using chick chorioallantoic membrane (CAM) model also showed that TNFα-induced angiogenesis and it was inhibited by AlE and its active principles. Further, in silico studies revealed that CA, CI and GA are capable of binding the TNFα-receptor-1 to mediate anti-TNFα activity. This study explains the immunomodulatory function of Triphala, evaluated in the context of retinal and choroid vasculopathies in vitro and ex vivo; which showed that CA, CI and GA can be a potential pharmacological agents in the management of DR and NV-AMD.

Photobiomodulation Inhibits Long-term Structural and Functional Lesions of Diabetic Retinopathy.

Previous studies demonstrated that brief (3 to 4 min) daily application of light at 670 nm to diabetic rodents inhibited molecular and pathophysiologic processes implicated in the pathogenesis of diabetic retinopathy (DR) and reversed diabetic macular edema in small numbers of patients studied. Whether or not this therapy would inhibit the neural and vascular lesions that characterize the early stages of the retinopathy was unknown. We administered photobiomodulation (PBM) therapy daily for 8 months to streptozotocin-diabetic mice and assessed effects of PBM on visual function, retinal capillary permeability, and capillary degeneration using published methods. Vitamin D receptor and Cyp24a1 transcripts were quantified by quantitative real-time PCR, and the abundance of c-Kit+ stem cells in blood and retina were assessed. Long-term daily administration of PBM significantly inhibited the diabetes-induced leakage and degeneration of retinal capillaries and also significantly inhibited the diabetes-induced reduction in visual function. PBM also inhibited diabetes-induced reductions in retinal Cyp24a1 mRNA levels and numbers of circulating stem cells (CD45-/c-Kit+), but these effects may not account for the beneficial effects of PBM on the retinopathy. PBM significantly inhibits the functional and histopathologic features of early DR, and these effects likely are mediated via multiple mechanisms.

Histological, morphometric, protein and gene expression analyses of rat retinas with ischaemia-reperfusion injury model treated with sildenafil citrate.

The aim of this study was to better understand the role of apoptosis in a retinal ischaemia-reperfusion injury model and to determine whether sildenafil citrate treatment can prevent retinal cell apoptosis. Thirty-six rats were divided into a control group (n = 6) and two experimentally induced ischaemia-reperfusion groups (7 and 21 days; n = 15 per group). The induced ischaemia-reperfusion groups were treated with sildenafil for 7 and 21 days (n = 10 per group), and 10 animals were treated with a placebo for the same period (n = 5 per group). Paracentesis of the anterior chamber was performed with a 30-G needle attached to a saline solution (0.9%) bag positioned at a height of 150 cm above the eye for 60 min. Intraocular pressure was measured by rebound tonometer (TonoVet® ). The eyes were analysed by histology and morphometry, and by immunohistochemistry and qRT-PCR for expression of Caspase-7, Caspase-6, Caspase-9, Tnf-r2, Fas-l, Bcl-2 and Bax. Sildenafil-treated animals showed lower levels of histopathological changes (inflammatory, cellular and tissue) than their placebo-treated counterparts at both 7 and 21 days. The retinal ganglion cell layer (RGC) was preserved in the sildenafil groups (SG), with a cell count closer to control than in the placebo groups (PG). Caspase-7 expression was significantly higher in both treated groups at 7 days compared to controls. Gene expression levels in both treatment groups differed from the controls, but in SG Bax and Caspase-6 expression levels were similar to control animals. These results suggest that the main mechanism of retinal cell death in this model is apoptosis, as there is an increase in pro-apoptotic factors and decrease in the anti-apoptotic ones. Also, sildenafil seems to protect the retinal ganglion cell layer from apoptosis. Cell survival was evident in the histological and morphometric analyses, and sildenafil treatment had a protective effect in the apoptosis pathways, with gene expression levels in SG similar to the controls.

Lipemia retinalis in an infant treated for retinopathy of prematurity.

Lipemia retinalis is an unusual ocular finding associated with hypertriglyceridemia. We report the case of an infant treated for retinopathy of prematurity who later developed lipemia retinalis, with triglyceride levels of 4736 mg/dl. There was a paradoxical worsening of hypertriglyceridemia with the use of medium chain triglyceride supplement. On discontinuing the supplement, the triglycerides level drastically dropped, and retinal vasculature returned to a normal hue.

Enhancement of scutellarin oral delivery efficacy by vitamin B12-modified amphiphilic chitosan derivatives to treat type II diabetes induced-retinopathy.

BACKGROUND: Diabetic retinopathy is the most common complication in diabetic patients relates to high expression of VEGF and microaneurysms. Scutellarin (Scu) turned out to be effective against diabetes related vascular endothelial cell dysfunction. However, its clinical applications have been limited by its low bioavailability. In this study, we formulated and characterized a novel intestinal target nanoparticle carrier based on amphiphilic chitosan derivatives (Chit-DC-VB12) loaded with scutellarin to enhance its bioavailability and then evaluated its therapeutic effect in experimental diabetic retinopathy model. RESULTS: Chit-DC-VB12 nanoparticles showed low toxicity toward the human colon adenocarcinoma (Caco-2) cells and zebra fish within concentration of 250 µg/ml, owing to good biocompatibility of chitosan. The scutellarin-loaded Chit-DC-VB12 nanoparticles (Chit-DC-VB12-Scu) were then prepared by self-assembly in aqueous solution. Scanning electron microscopy and dynamic light scattering analysis indicated that the Chit-DC-VB12-Scu nanoparticles were spherical particles in the sizes ranging from 150 to 250 nm. The Chit-DC-VB12-Scu nanoparticles exhibited high permeation in Caco-2 cell, indicated it could be beneficial to be absorbed in humans. We also found that Chit-DC-VB12 nanoparticles had a high cellular uptake. Bioavailability studies were performed in Sprague-Dawley rats, which present the area under the curve of scutellarin of Chit-DC-VB12-Scu was two to threefolds greater than that of free scutellarin alone. Further to assess the therapeutic efficacy of diabetic retinopathy, we showed Chit-DC-VB12-Scu down-regulated central retinal artery resistivity index and the expression of angiogenesis proteins (VEGF, VEGFR2, and vWF) of retinas in type II diabetic rats. CONCLUSIONS: Chit-DC-VB12 nanoparticles loaded with scutellarin have better bioavailability and cellular uptake efficiency than Scu, while Chit-DC-VB12-Scu nanoparticles alleviated the structural disorder of intraretinal neovessels in the retina induced by diabetes, and it also inhibited the retinal neovascularization via down-regulated the expression of angiogenesis proteins. In conclusion, the Chit-DC-VB12 nanoparticles enhanced scutellarin oral delivery efficacy and exhibited potential as small intestinal target promising nano-carriers for treatment of type II diabetes induced-retinopathy.

Jiangtang Xiaozhi Recipe () prevents diabetic retinopathy in streptozotocin-induced diabetic rats.

OBJECTIVE: To evaluate the prevention effect of diabetic retinopathy of Jiangtang Xiaozhi Recipe (, JXR) in streptozotocin (STZ)-induced diabetic rats. METHODS: Sprague-Dawley rats were randomly divided into normal control group and diabetic group. Rats in the diabetic group were induced by intraperitoneal administration of STZ (50 mg/kg), and subdivided into 5 groups. Rats in the diabetic control group were given saline; four treatment groups were given metformin (300 mg/kg), JXR (2, 4 and 8 g/kg) respectively for 8 weeks, while rats in the normal control group were injected with citrate buffer and given the same volume of vehicle. Body weight and food intake were measured every week. The hypoglycaemic effects were determined by testing fasting blood glucose (FBG) every other week, and hemoglobin A1c (HbA1c), insulin, and glucagon at the end of the treatment. The preventive effects of JXR on STZ-induced diabetic rats were determined by histopathological examination with hematoxylin and eosin staining, and periodic acid-schiff staining. The effects were further evaluated by serum superoxide dismutase (SOD) activity and malondialdehyde (MDA). RESULTS: High-dose JXR significantly reduced FBG and HbA1c level at the 8th week of administration (P<0.01, P<0.05). JXR significantly increased insulin level (P<0.05), and decreased glucagon level (P<0.05). JXR showed the antioxidant defense with increased SOD activity and decreased MDA contents in diabetic rats. Histopathological studies revealed that there were no basement membrane thickening and mild destruction in the treated groups. Morphometric measurements of retina microvascular showed that acellular capillary and capillary density decreased in treated rats while pericyte and endothelial cell increasing after the treatment. CONCLUSION: JXR have protective effect of diabetic retinopathy and its mechanism may be associated with the obvious hypoglycemic and antioxidant effect.

Lutein facilitates physiological revascularization in a mouse model of retinopathy of prematurity.

BACKGROUND: Retinopathy of prematurity is one of the leading causes of childhood blindness worldwide, with vessel growth cessation and vessel loss in phase I followed by neovascularization in phase II. Ischaemia contributes to its pathogenesis, and lutein protects against ischaemia-induced retinal damages. We aimed to investigate the effects of lutein on a murine model of oxygen-induced retinopathy. METHODS: Mouse pups were exposed to 75% oxygen for 5 days and returned to room air for another 5 days. Vascular obliteration, neovascularization and blood vessel leakage were examined. Immunohistochemistry for glial cells and microglia were performed. RESULTS: Compared with vehicle controls, mouse pups receiving lutein treatment displayed smaller central vaso-obliterated area and reduced blood vessel leakage. No significant difference in neovascular area was found between lutein and vehicle controls. Lutein promoted endothelial tip cell formation and maintained the astrocytic template in the avascular area in oxygen-induced retinopathy. No significant changes in Müller cell gliosis and microglial activation in the central avascular area were found in lutein-treated pups. CONCLUSIONS: Our observations indicated that lutein significantly promoted normal retinal vascular regrowth in the central avascular area, possibly through promoting endothelial tip cell formation and preserving astrocytic template. Our results indicated that lutein might be considered as a supplement for the treatment of proliferative retinopathy of prematurity because of its role in facilitating the revascularization of normal vasculature.

Lonicerae Japonicae Flos attenuates diabetic retinopathy by inhibiting retinal angiogenesis.

ETHNOPHARMACOLOGICAL RELEVANCE: Lonicerae Japonicae Flos (Jin-Yin-Hua) is a well-known traditional Chinese medicine used for clearing away heat and toxic material. AIM OF THE STUDY: This study aims to observe the attenuation of aqueous extract of Lonicerae Japonicae Flos (FL) against streptozotocin (STZ)-induced diabetic retinopathy (DR) and its engaged mechanism. MATERIALS AND METHODS: STZ-induced proliferative DR (PDR) for 5 month in C57BL/6 mice was used in this study. Retinal vessels were observed by immunofluorescence staining with cluster of differentiation 31 (CD31) and histopathological evaluation. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum vascular endothelial growth factor (VEGF) content. Cell proliferation was detected by 3-(4, 5-dimethylthiazol-2-yl) 2, 5-diphenyltetrazolium bromide (MTT) assay in choroid-retinal endothelial RF/6A cells. VEGF-induced tube formation in RF/6A cells was observed. The contents of chlorogenic acid (CGA), caffeic acid (CA), and luteolin in FL were detected by high-performance liquid chromatography (HPLC). RESULTS: Histopathological evaluation demonstrated that retinal vessels were increased in STZ-induced PDR mice, whereas FL decreased such increase. The results of CD31 staining also showed that FL decreased the increased number of retinal vessels in STZ-induced PDR mice. In addition, FL reduced the increased serum VEGF content in STZ-induced PDR mice. FL reduced VEGF-induced RF/6A cell proliferation in the concentration-dependent manner, but had no obvious effect on RF/6A cell viability without VEGF stimulation. VEGF-induced tube formation in RF/6A cells was inhibited by different concentrations of FL. CGA, CA and luteolin all inhibited VEGF-induced tube formation in RF/6A cells, and the lowest effective concentration of CGA and CA was both 0.625µM, but of luteolin was 5µM. Furthermore, the results of HPLC demonstrated that the amount of CGA was the highest in FL. CONCLUSIONS: FL ameliorates STZ-induced PDR by inhibiting retinal angiogenesis. Phenolic acid CGA is the main compound contributing to the inhibition of FL on retinal angiogenesis.