Retinal Venules Research Articles

Case report: Infectious mononucleosis with bilateral retinal haemorrhages under myelin oligodendrocyte glycoprotein antibody-associated disease

BackgroundBilateral optic neuritis associated with optic disc swelling is a common feature of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). However, extensive deep retinal haemorrhages have not been described in the context of MOG-associated optic neuritis. Here, we report a case of infectious mononucleosis with marked binocular peripapillary and perivascular haemorrhages as well as extensive deep retinal haemorrhages in the presence of MOGAD.Case reportA 39-year-old Chinese woman presenting with subacute binocular vision reduction with no light perception was diagnosed with MOGAD. Fundus examination revealed the presence of binocular peripapillary and perivascular haemorrhages as well as extensive deep retinal haemorrhages with severe optic disc swelling greater in the right eye than in the left and dilated and tortuous retinal venules. The patient tested positive for the Epstein–Barr virus (EBV) antigen (595 U/mL) and the EBV capsid antigen (>750 U/mL). She had a fever and right upper quadrant abdominal pain, and a doctor determined splenomegaly 1 week before the onset of orbital pain and decreased vision acuity. Medical history and laboratory tests indicated the presence of concurrent infectious mononucleosis. Other investigational indicators of retinal haemorrhages, including hypertension, diabetes mellitus, vascular disease, systemic lupus erythematosus, metabolic disease, and renal or liver dysfunction, were absent.DiscussionThis case suggests that retinal haemorrhage is a possible complication of infectious mononucleosis in the presence of MOGAD.

Intracranial pressure affects retinal venular complexity in idiopathic intracranial hypertension: a retrospective observational study

BackgroundIncreased intracranial pressure (ICP) in patients with idiopathic intracranial hypertension (IIH) affects the retinal microvasculature, which can be imaged and quantified by optical coherence tomography angiography (OCTA). We aimed to identify the mediating factor between ICP and OCTA parameters association in IIH patients.MethodsIIH patients with active intracranial hypertension were enrolled. OCTA imaging was performed after ICP measurement. We quantified the branching complexity of the retinal arterioles and venules from the superficial vascular complex of the OCTA image. Eyes of IIH patients were stratified into eyes with papilledema (IIH-P) and eyes without papilledema (IIH-WP). All participants underwent visual acuity (VA) examination.ResultsOne hundred and thirty-eight eyes from 70 IIH patients and 146 eyes from 73 controls were included. Compared to the control group, IIH patients and IIH-P had reduced arteriole complexity and increased venule complexity (p < 0.05). For IIH patients and IIH-P, increased retinal venule complexity correlated with increased ICP and reduced VA (p < 0.05); while decreased arteriole complexity only correlated with Frisen scores (p = 0.026). Papilledema mediated the effect (p < 0.001) between ICP and arteriole complexity while ICP had a direct effect (p < 0.001) on venule complexity.ConclusionRetinal venules imaged via OCTA may reflect ICP levels and may underpin the direct effect of increased ICP in IIH patients.

Reassessment of arterial versus venous perfusion of diabetic retinal neovascularization using ultrawide-field fluorescein angiography.

The purpose of this study was to assess whether diabetic NV is perfused by the arterial or the venous circulation. This is a retrospective, consecutive case series evaluating patients with proliferative diabetic retinopathy (PDR) imaged with ultrawide-field (UWF) fluorescein angiography (FA). Areas of neovascularization elsewhere (NVE) and neovascularization of the disc (NVD) were assessed. Perfusion was defined as arterial, arteriovenous, or venous if the area of diabetic neovascularization (NV) began to hyperfluoresce either prior, during, or after laminar venous flow, respectively. A total of 180 eyes from 176 patients with 928 NV were identified (830 NVE, 98 NVD). Of those, 5.1% of NVE were classified as arterial and 58.2% of NVD were classified as arterial. The remaining NV were classified as arteriovenous except for a small subset (6.1%) which were indeterminate. None of the NV were classified as venous. Noteworthy examples demonstrated NV that nearly fully perfused prior to any detectable fluorescence within nearby veins as well as clear shunting of blood from a feeding artery to a draining vein. UWF FA images suggest that some NV is perfused by retinal arteries. This may be useful in devising strategies for early detection and treatment of NV precursors. What is known • Diabetic retinal neovascularization has long been thought to be perfused by the retinal venous circulation. • Vascular endothelial growth factor has been shown to play key roles in both angiogenesis and arteriogenesis. What is new • Ultrawide-field fluorescein angiography demonstrates that at least some diabetic neovascularization is perfused by the retinal arterial circulation. • This supports the hypothesis that diabetic neovascularization may arise from arterially-perfused intraretinal microvascular abnormalities in the capillary bed.

In Vivo Visualization of Intravascular Patrolling Immune Cells in the Primate Eye.

Insight into the immune status of the living eye is essential as we seek to understand ocular disease and develop new treatments. The nonhuman primate (NHP) is the gold standard preclinical model for therapeutic development in ophthalmology, owing to the similar visual system and immune landscape in the NHP relative to the human. Here, we demonstrate the utility of phase-contrast adaptive optics scanning light ophthalmoscope (AOSLO) to visualize immune cell dynamics on the cellular scale, label-free in the NHP. Phase-contrast AOSLO was used to image preselected areas of retinal vasculature in five NHP eyes. Images were registered to correct for eye motion, temporally averaged, and analyzed for immune cell activity. Cell counts, dimensions, velocities, and frequency per vessel were determined manually and compared between retinal arterioles and venules. Based on cell appearance and circularity index, cells were divided into three morphologies: ovoid, semicircular, and flattened. Immune cells were observed migrating along vascular endothelium with and against blood flow. Cell velocity did not significantly differ between morphology or vessel type and was independent of blow flood. Venules had a significantly higher cell frequency than arterioles. A higher proportion of cells resembled "flattened" morphology in arterioles. Based on cell speeds, morphologies, and behaviors, we identified these cells as nonclassical patrolling monocytes (NCPMs). Phase-contrast AOSLO has the potential to reveal the once hidden behaviors of single immune cells in retinal circulation and can do so without the requirement of added contrast agents that may disrupt immune cell behavior.

From blindness to light: A clinical conundrum - central retinal vein occlusion as an initial manifestation of inflammatory bowel disease

This case report emphasizes central retinal vein occlusion (CRVO) as the primary cause of blindness, typically linked to impaired retinal venous drainage from critical vein obstruction. While conditions like diabetes and hypertension are known risk factors for CRVO, rare instances associate it with inflammatory bowel disease (IBD). Here, a 19-year-old male initially presented with painless vision loss, revealing ocular ischemia secondary to panuveitis and moderate CRVO. Genetic testing indicated HLA-B51/B52, suggesting Behcet's disease initially, treated with immunosuppressants and steroids. Despite initial recovery, severe gastrointestinal symptoms later led to ulcerative colitis diagnosis. This sequence highlights CRVO preceding IBD symptoms in a high-risk individual, prompting caution in its differential diagnosis, especially in younger patients without typical risk factors. Prompt recognition and a collaborative approach between gastroenterologists and ophthalmologists are crucial for improving patient outcomes.

Bilateral optic nerve infiltration and leukemic retinopathy as initial signs of leukemia relapse with central nervous system involvement in an adult: a case report

BackgroundWe describe a case in which bilateral optic nerve infiltration and leukemic retinopathy were the initial signs of disease relapse in a patient with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+-ALL) with central nervous system (CNS) involvement.Case presentationA 65-year-old Asian female with Ph+-ALL in complete remission presented at our institution with symptoms of visual disturbance, central scotoma and pain with eye movement in both eyes for a 1-month duration. Ophthalmic examination revealed remarkable optic disc swelling with multiple flame-shaped peripapillary hemorrhages, retinal venous dilation and retinal hemorrhages in both eyes. She was subsequently referred to the treating oncologist and diagnosed with Ph+-ALL relapse with multiple relapsed diseases involving the bone marrow and CNS. After intrathecal (IT) therapy, her visual acuity dramatically improved, and her leukemic infiltrates decreased.ConclusionsTo the best of our knowledge, this is the first case report of ALL relapse with CNS involvement presenting as bilateral optic nerve infiltration and leukemic retinopathy in an adult. Hence, we highlight the priority and sensitivity of ophthalmic examinations, as they are noninvasive methods for detecting leukemia relapse.

Retinal vascular changes and arterial stiffness during 8-month isolation and confinement: the SIRIUS-21 space analog mission.

Isolation and confinement are significant stressors during space travel that can impact crewmembers' physical and mental health. Space travel has been shown to accelerate vascular aging and increase the risk of cardiovascular and cerebrovascular disorders. However, the effect of prolonged isolation and confinement on microvascular function has not yet been thoroughly investigated. Retinal vascular imaging was conducted on four crewmembers during- and post-8-month SIRIUS-21 space analog mission. Central retinal arteriolar equivalent (CRAE), central retinal venular equivalent (CRVE), and arteriovenous ratio (AVR) were measured. Pulse wave velocity (PWV), an indicator of arterial stiffness, was also measured. Data from 4 participants was analyzed. These participants had a mean age of 34.75 ± 5.44years, height of 170.00 ± 2.00cm, weight of 74.50 ± 12.53kg, and average BMI of 25.47 ± 3.94kg/m2. During- and post-isolation, average CRVE showed an upward trend (Pearson's r 0.784, R-square 0.62), suggesting a dilation of retinal venules, while AVR showed a downward trend (Pearson's r -0.238, R-square 0.057), which is suggestive of a higher risk of cardiovascular and cerebrovascular dysfunctions. But neither of these trends were statistically significant. Additionally, the average PWV showed an upward trend during- and after-isolation across all crew members. Isolation and confinement appear to contribute towards retinal vascular damage and arterial stiffness. This cautiously suggests an increased risk of cardiovascular and cerebrovascular disorders due to the contribution of the isolation in space flight. Further studies are needed to confirm and expand on these results as we prepare for future manned missions to the Moon and Mars.

LUNet: deep learning for the segmentation of arterioles and venules in high resolution fundus images

Objective. This study aims to automate the segmentation of retinal arterioles and venules (A/V) from digital fundus images (DFI), as changes in the spatial distribution of retinal microvasculature are indicative of cardiovascular diseases, positioning the eyes as windows to cardiovascular health. Approach. We utilized active learning to create a new DFI dataset with 240 crowd-sourced manual A/V segmentations performed by 15 medical students and reviewed by an ophthalmologist. We then developed LUNet, a novel deep learning architecture optimized for high-resolution A/V segmentation. The LUNet model features a double dilated convolutional block to widen the receptive field and reduce parameter count, alongside a high-resolution tail to refine segmentation details. A custom loss function was designed to prioritize the continuity of blood vessel segmentation. Main Results. LUNet significantly outperformed three benchmark A/V segmentation algorithms both on a local test set and on four external test sets that simulated variations in ethnicity, comorbidities and annotators. Significance. The release of the new datasets and the LUNet model (www.aimlab-technion.com/lirot-ai) provides a valuable resource for the advancement of retinal microvasculature analysis. The improvements in A/V segmentation accuracy highlight LUNet's potential as a robust tool for diagnosing and understanding cardiovascular diseases through retinal imaging.

Three-Year Follow-Up Study Investigating Changes in Retinal Vascular Morphology and the Relationship with Diabetic Retinopathy in Children with Type 1 Diabetes Mellitus.

This study aimed to investigate changes in retinal microvascular morphology and associated factors, and their relationship with diabetic retinopathy (DR) in children with type 1 diabetes mellitus (T1DM). Thirty-eight children enrolled in this 3-year follow-up study underwent complete ophthalmic examinations including fundus photography. Retinal vascular parameters were measured automatically and compared between baseline and follow-up. Multiple linear regression was used to investigate factors affecting changes in vascular parameters. Binary logistic regression was used to analyze the relationship between retinal microvascular morphology and DR. The caliber of all retinal vessels (within 1-1.5 papillary diameter [PD] from the center of the optic disc, p = 0.030; 1.5-2 PD, p = 0.003), arterioles, and venules (1.5-2 PD, p = 0.001) was narrower in nearly all regions in the follow-up group compared with the baseline group. Vascular tortuosity increased in the central part of the retina and decreased in the periphery. The density (1-1.5 PD, p = 0.030) and fractal dimension (p = 0.037) of retinal vessels were increased at the end of the follow-up compared with baseline. Retinal vascular caliber was independently correlated with DR (odds ratio 0.793 [95% confidence interval 0.633-0.993]; p = 0.044). Retinal microvascular morphology in children with T1DM varied with the disease course. Narrower retinal vessels may be an independent risk factor for DR. Results of this study emphasized the importance of regular follow-up of fundus vascular morphology for the detection of early DR in children with T1DM.

Pretreatment ocular blood flow and retinal oxygen metabolism inthe acute uveitic phase is associated with final outcome in Vogt-Koyanagi-Harada disease.

To investigate the association between pretreatment blood flow velocity in the choroid and optic nerve head (ONH) and retinal oxygen metabolism in the acute uveitic phase and the development of 'sunset glow fundus' in Vogt-Koyanagi-Harada (VKH) disease. Retrospective analysis of 41 patients (82 eyes). Laser speckle flowgraphy and retinal oximetry measurements were performed at the presentation. The main outcome measure was the development of 'sunset glow fundus'. Twenty patients (40 eyes) presented in the phase preceding anterior segment inflammation (early presentation), and 21 patients (42 eyes) presented with anterior segment inflammation (late presentation). In ONH, mean blur rate (MBR)-vessel, representing blood flow velocity in retinal vessels, was significantly lower in the late presentation group, while choroidal MBR was not significantly different. The late presentation group had significantly lower oxygen saturation in retinal venules, a higher arteriovenous oxygen saturation difference and a smaller calibre of retinal arterioles compared with the early presentation group. Eyes that subsequently developed 'sunset glow fundus' had significantly lower ONH MBR-vessels, lower oxygen saturation in retinal venules, a higher arteriovenous oxygen saturation difference and a smaller calibre of retinal arterioles compared with eyes without 'sunset glow fundus'. ONH MBR-vessel had a significant negative correlation with arteriovenous oxygen saturation difference and a significant positive correlation with calibre of retinal arterioles. In the acute uveitic phase of VKH disease, the development of 'sunset glow fundus' is associated with pretreatment reduced retinal blood flow velocity, calibre of retinal arterioles and oxygen saturation in retinal venules, as well as an increased arteriovenous oxygen saturation difference.

Remnant cholesterol is correlated with retinal vascular morphology and diabetic retinopathy in type 2 diabetes mellitus: a cross-sectional study

BackgroundThe association between remnant cholesterol (RC) and diabetic retinopathy (DR) in type 2 diabetes mellitus (T2DM) remains unclear. Morphological changes in retinal vessels have been reported to predict vascular complications of diabetes, including DR.MethodsThis cross-sectional study included 6535 individuals with T2DM. The RC value was calculated using the recognized formula. The retinal vascular parameters were measured using fundus photography. The independent relationship between RC and DR was analyzed using binary logistic regression models. Multiple linear regression and subgroup analyses were employed to investigate the link between RC and vascular parameters, including the retinal arteriolar diameter (CRAE), venular diameter (CRVE), and fractal dimension (Df). Mediation analysis was performed to assess whether the vascular morphology could explain the association between RC and DR.ResultsRC was independently associated with DR in patients with a longer duration of T2DM (> 7 years). Patients with the highest quartile RC levels had larger CRAE (5.559 [4.093, 7.025] μm), CRVE (7.620 [5.298, 9.941] μm) and Df (0.013 [0.009, 0.017]) compared with patients with the lowest quartile RC levels. Results were robust across different subgroups. The association between RC and DR was mediated by CRVE (0.020 ± 0.005; 95% confidence interval: 0.012–0.032).ConclusionsRC may be a risk factor for DR among those who have had T2DM for a longer period of time. Higher RC levels were correlated with wider retinal arterioles and venules as well as higher Df, and it may contribute to DR through the dilation of retinal venules.

Retinal Changes in Patients With Covid-19 and Different Expressiveness of Metabolic Changes.

To study the relationship between the severity of COVID-induced metabolic changes and the structure and frequency of retinal changes, according to funduscopy data in patients with different clinical courses of COVID-19. 117 patients with COVID-19 were examined. While examining patients, severity of the course of COVID-19, the expressiveness of changes in the metabolic status were determined; fundus image registration was performed with portable fundus cameras Pictor Plus Fundus Camera and VistaView (Volk Optical). As a result of the research, retinal changes were found in 49 (41.9 %) patients with COVID-19. In 8 (16.3 %) cases, clinically significant (vitreous hemorrhage, prethrombosis of the central retinal vein or branches of the central retinal vein, thrombosis of the central retinal vein or branches of the central retinal vein) COVID-induced retinal and ophthalmological changes were observed, which caused a decrease in visual acuity. In 41 (83.7 %) cases, clinically insignificant changes (cotton wool spots, narrowed retinal vessels, intraretinal and petechial hemorrhages, tortuosity and dilatation of retinal venules) COVID-induced retinal changes were observed. Clinically significant retinal changes occur in patients with a statistically significantly higher level of D-dimer and a greater percentage of lung parenchyma lesion than in the group of patients with clinically insignificant retinal changes (p &lt; 0.05). The structure of retinal changes in patients with COVID-19 correlates with the severity of the clinical course of the disease and changes in the metabolic status of patients. Metabolic changes are correlated with retinal changes and can be predictive for preventing general vascular complications in COVID-19.

Manifestations of systemic disease in the retina and fundus of cats and dogs.

The fundus is unique in that it is the only part of the body that allows for a noninvasive and uninterrupted view of vasculature and nervous tissue. Utilization of this can be a powerful tool in uncovering salient incidental findings which point to underlying systemic diseases, and for monitoring response to therapy. Retinal venules and arterioles allow the clinician to assess changes in vascular color, diameter, outline, and tortuosity. The retina and optic nerve may exhibit changes associated with increased or decreased thickness, inflammatory infiltrates, hemorrhages, and detachments. While some retinal manifestations of systemic disease may be nonspecific, others are pathognomonic, and may be the presenting sign for a systemic illness. The examination of the fundus is an essential part of the comprehensive physical examination. Systemic diseases which may present with retinal abnormalities include a variety of disease classifications, as represented by the DAMNIT-V acronym, for Degenerative/Developmental, Anomalous, Metabolic, Neoplastic, Nutritional, Inflammatory (Infectious/Immune-mediated/ischemic), Toxic, Traumatic and Vascular. This review details systemic illnesses or syndromes that have been reported to manifest in the fundus of companion animals and discusses key aspects in differentiating their underlying cause. Normal variations in retinal anatomy and morphology are also considered.

Retinal oximetry and microvascular assessment after hypertensive pregnancy complications.

Women with hypertensive disorders of pregnancy (HDP) are at increased risk of developing premature cardiovascular disease (CVD). The mechanisms behind this are not fully understood, but microvascular alterations have been documented in retinal arterioles and venules. The aim of this study was to use non-invasive retinal imaging to investigate the structural and functional properties of arterioles, venules and capillaries in this patient group. We examined 27 women with previous HDP and 23 controls at 3 years postpartum. The retinal microvasculature was assessed by vessel calibre measurements, retinal oximetry and optical coherence tomography angiography. Differences were analysed using non-parametric tests and multiple regression analyses, adjusted for age and body mass index. Median arteriolar oxygen saturation (SaO2; 94.2% vs. 93.0%), venular oxygen saturation (SvO2; 60.1% vs. 62.4%) and arteriovenous saturation difference (AV-difference; 32.8% vs. 32.3%) were similar across groups. Capillary vessel density (VD; 46.2% vs. 46.3%), skeletonised VD (VSD; 21.3 vs. 21.1 mm/mm2) and vessel diameter index (21.65 vs. 21.86) were also comparable. In the HDP group, mean arterial pressure (MAP) was positively correlated with AV-difference (R2 = 0.209) and negatively correlated with arteriolar diameter (CRAE; r2 = 0.382). Structural microvascular alterations appear not to be key biomarkers for CVD risk after HDP as early as 3 years postpartum in otherwise healthy women. Further studies are needed to evaluate whether such changes occur later in life. MAP was associated with AV-difference only in the HDP group, suggesting specific mechanisms affecting functional microvascular properties in these women.

Artificial Intelligence-based quantitative evaluation of retinal vascular parameters in thyroid-associated ophthalmopathy.

Thyroid-associated ophthalmopathy (TAO) may result in increased metabolism and abnormalities in microcirculation. The fractal dimension (Df) of retinal vessels has been shown to be related to the pathology of a number of ophthalmic disorders, but it hasn't been investigated in TAO. We analyzed 1078 participants aged 18 to 72 (548 healthy volunteers and 530 TAO). Images were captured using a non-mydriatic 45-degree fundus camera. Baseline retinal characteristics, such as vessel width, tortuosity, and Df were measured using semiautomated software from fundus images. The average retinal parameters were compared between the two groups. The receiver operation curve (ROC) was used to assess the diagnostic efficacy of various retinal vascular parameters for TAO. Despite controlling for potential confounding variables, Df, vessel width, and tortuosity significantly increased in TAO compared to healthy volunteers. Compared to active TAO, patients in the inactive phase had a larger retinal venous caliber (p < 0.05), but there was no difference in Df or arterial caliber. Moderate and severe cases had a higher Df compared with mild cases (EUGOGO guidelines). The area under the ROC for Df, tortuosity, and vascular caliber in the diagnosis of TAO was 0.904 (95% CI: 0.884-0.924), 0.638 (95% CI: 0.598-0.679), and 0.617 (95% CI: 0.576-0.658), respectively. Due to its accessibility, affordability, and non-invasive nature, retinal vascular Df may serve as a surrogate marker for TAO and might be used to identify severe cases. With relatively high diagnostic performance, the Df is of some utility for the detection of TAO.

ENDOTHELIN-1 ROLE IN HUMAN EYE: A SYSTEMATIC REVIEW

Background: Endothelin-1 (ET-1) is a potent vasoactive factor implicated in development of diabetic retinopathy, which is commonly associated with retinal edema and hyperglycemia. Although the vasomotor activity of venules contributes to the regulation of tissue fluid homeostasis, responses of human retinal venules to ET-1 under euglycemia and hyperglycemia remain unknown and the ET-1 receptor subtype corresponding to vasomotor function has not been determined. The aim: This study aims to show endothelin-1 role in human eye. Methods: By comparing itself to the standards set by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020, this study was able to show that it met all of the requirements. So, the experts were able to make sure that the study was as up-to-date as it was possible to be. For this search approach, publications that came out between 2013 and 2023 were taken into account. Several different online reference sources, like Pubmed and SagePub, were used to do this. It was decided not to take into account review pieces, works that had already been published, or works that were only half done. Result: In the PubMed database the results of our search brought up 44 articles, whereas the results of our search on SagePub brought up 95 articles. The results of the search conducted for the last year of 2013 yielded a total 15 articles for PubMed and 42 articles for SagePub. The result from title screening, a total 4 articles for PubMed and 12 articles for SagePub. In the end, we compiled a total of 8 papers. We included five research that met the criteria. Conclusion: ET-1 (vasoconstrictor, mitogenic, pro-oxidative, and proinflammatory) is one of the most potent vasoconstrictors in the body and its action has a dual effect: on the one hand, it acts on receptors of ECs and pericytes; on the other hand, it has a mitogenic effect on VSMCs.

Retinal Changes in a Patient with a Traumatic Orbital Subperiosteal Hematoma and Superior Ophthalmic Vein Compression

Purpose: We describe a case with retinal alterations similar to those of nonischemic central retinal vein occlusion, but also with superior ophthalmic vein compression attributable to a traumatic, subperiosteal orbital hematoma.Case summary: A 13-year-old male presented with left periorbital edema, a decrease in vision, and diplopia after blunt periorbital trauma. In ophthalmological evaluations, the best-corrected visual acuity (BCVA) was 0.4 (20/50) and a severe supraduction limitation was apparent (grade -4). Fundus examination revealed optic disc swelling, retinal vein dilation/tortuosity, and an arteriovenous transit time delay of 26s. Fluorescein angiography evidenced optic disc leakage. Ocular sonography and orbital magnetic resonance imaging revealed a superior subperiosteal hematoma in the left orbit accompanied by superior ophthalmic vein compression. We scheduled emergency hematoma evacuation. One month later, the BCVA had increased to 1.0 (20/20) and ocular movement was no longer limited. Orbital computed tomography showed that the superior ophthalmic vein compression had resolved and that the abnormalities observed in the initial fundus examination and fluorescein angiography had improved.Conclusions: Retinal changes that resemble nonischemic central retinal vein occlusion including retinal venous dilation and tortuosity may develop after a traumatic, orbital subperiosteal hematoma. Compressive obstruction of the superior ophthalmic vein may then be in play. Early surgical intervention featuring hematoma evacuation may prevent irreversible visual deterioration.

Retinal arterial-venous pulse delay: a new specific marker for a carotid-cavernous fistula.

The purpose of the study was to describe ocular blood flow changes in eyes affected by a carotid-cavernous fistula (CCF) using laser speckle flowgraphy. We hypothesized that imaging blood flow velocity waveforms in the retinal arterioles and venules simultaneously would reveal specific characteristics of an arteriovenous (AV) connection. The study was an observational case series, with a retrospective case-control analysis. Five patients with a CCF underwent measurement of ocular blood flow using laser speckle flowgraphy. The blood flow was compared retrospectively between a control group of healthy subjects (n = 32) and patients with an elevated intraocular pressure or venous outflow impairment without an AV fistula (n = 40). The outcomes were derived from the arteriole and venule blood flow velocity waveforms, including an A-V phase delay and flow pulsatility. The presence of an active CCF was associated with an increased delay in the peak velocity measured in the retinal venule (10.7% ± 2.2% of the cardiac cycle duration) compared with unaffected fellow eyes (1.8% ± 0.2%; p = 0.05) or control eyes of normal subjects (2.7% ± 0.3%; p = 0.02). This delay disappeared after fistula thrombosis and was not present in eyes with a central retinal vein occlusion (CRVO), glaucoma, non-arteritic anterior ischemic optic neuropathy (NAION), or papilledema. The venule blood flow velocity decreased during systole (and in some cases momentarily stopped), leading to a delayed pulse with a greater amplitude in the venules than in fellow eyes and normal controls after normalizing to the arteriole amplitude (1.71 ± 0.3 vs 0.54 ± 0.03 vs 0.59 ± 0.02; p = 8.0E-12). This specific AV delay could also be identified in a scanning laser ophthalmoscope (SLO; SPECTRALIS®) video. Laser speckle flowgraphy reveals dynamic retinal vascular changes in eyes affected by a CCF, which are not present in healthy controls or patients with other eye conditions, and which reverses with treatment.

Increased Oxygen Saturation in Retinal Venules During Isometric Exercise Is Accompanied With Increased Peripheral Blood Flow in Normal Persons.

A recent study has shown that an increase in the arterial blood pressure of approximately 10 mm Hg in healthy persons can increase the oxygen saturation in venules from the retinal periphery but not from the macular area. The purpose of the present study was to investigate whether a higher increase in blood pressure has further effects on oxygen saturations and whether this is accompanied with changes in retinal blood flow. In 30 healthy persons, oxygen saturation, diameter, and blood flow were measured in arterioles to and venules from the retinal periphery and the macular area. The experiments were performed before and during an experimental increase in arterial blood pressure of (mean ± SD) 18.3 ± 6.2 mm Hg. A higher number of venules than arterioles branching from the temporal vascular arcades to the macular area was balanced by a smaller diameter of the venules. Isometric exercise induced significant contraction of both peripheral and macular arterioles (P<0.01 for both comparisons) and significant increase in oxygen saturation in both peripheral and macular venules (P<0.001 for both comparisons). This was accompanied with a significant increase in the blood flow in the peripheral arterioles and venules (P=0.4 for both comparisons), but not in their macular counterparts (P>0.06 for both comparisons). Increased systemic blood pressure leading to arterial contraction and increased venous oxygen saturation in the retina in normal persons can increase peripheral blood flow without significant effects on macular blood flow. This may contribute to explaining regional differences in the response pattern of retinal vascular disease.

Autonomous assessment of spontaneous retinal venous pulsations in fundus videos using a deep learning framework

The presence or absence of spontaneous retinal venous pulsations (SVP) provides clinically significant insight into the hemodynamic status of the optic nerve head. Reduced SVP amplitudes have been linked to increased intracranial pressure and glaucoma progression. Currently, monitoring for the presence or absence of SVPs is performed subjectively and is highly dependent on trained clinicians. In this study, we developed a novel end-to-end deep model, called U3D-Net, to objectively classify SVPs as present or absent based on retinal fundus videos. The U3D-Net architecture consists of two distinct modules: an optic disc localizer and a classifier. First, a fast attention recurrent residual U-Net model is applied as the optic disc localizer. Then, the localized optic discs are passed on to a deep convolutional network for SVP classification. We trained and tested various time-series classifiers including 3D Inception, 3D Dense-ResNet, 3D ResNet, Long-term Recurrent Convolutional Network, and ConvLSTM. The optic disc localizer achieved a dice score of 95% for locating the optic disc in 30 milliseconds. Amongst the different tested models, the 3D Inception model achieved an accuracy, sensitivity, and F1-Score of 84 ± 5%, 90 ± 8%, and 81 ± 6% respectively, outperforming the other tested models in classifying SVPs. To the best of our knowledge, this research is the first study that utilizes a deep neural network for an autonomous and objective classification of SVPs using retinal fundus videos.