Search

Background: To evaluate the effect and factors associated with the reactivation of retinopathy of prematurity (ROP) after intravitreal conbercept or aflibercept. Methods: We retrospectively reviewed the medical records of 176 eyes diagnosed with ROP and treated with anti-VEGF therapy between January 2018 and September 2022. The rate of reactivation and complications were assessed during the follow-up period. The factors of reactivation of ROP after intravitreal conbercept or aflibercept were analyzed on the basis of clinical factors and retinal parameters. Results: Reactivation of ROP occurred in 10 eyes (13.9%) after intravitreal conbercept and 13 eyes (12.5%) after intravitreal aflibercept (P = 0.79). The interval between injection and reactivation was significantly longer in the aflibercept group than in the conbercept group (15.50 ± 4.05 vs. 5.36 ± 0.50 weeks) (P < 0.001). The central retinal arteriolar equivalent (CRAE) of aggressive ROP was larger than that of type 1 prethreshold and threshold ROP before anti-VEGF therapy (P < 0.05). Zone I and stage 3 exhibited a positive correlation with the reactivation of retinopathy of prematurity (ROP) [odds ratio (OR) = 20.15, 5.02]. The changes in CRAE of pre-and post-therapy and gestational age were identified as potential protective factors for these outcomes (OR = 0.23, 0.49). Conclusions: Conbercept and aflibercept are effective for treating ROP. Aflibercept resulted in longer treatment intervals compared to conbercept. Zone, stage, and gestational age were associated with the reactivation of ROP. CRAE was associated with not only the severity of ROP but also its reactivation. Additionally, it may be an objective indicator in the early indication and follow-up of ROP. [ABSTRACT FROM AUTHOR]

Clinical relevance: Clinical assessment of age-related macular degeneration (AMD) relies on biomarkers that do not necessarily reflect the contributions of vascular dysfunction. Validation of clinically accessible methods of measuring retinal vascular integrity could provide a more holistic understanding of AMD-related changes to facilitate appropriate care. Background: There is conflicting evidence if retinal vessel calibre is significantly altered in the early stages of AMD. This study examined the outer and inner diameters of first order retinal vessels in intermediate AMD eyes using en face optical coherence tomography (OCT). Methods: Retinal en face (6 × 6 mm) OCT images were examined in a single eye of participants with intermediate AMD (n = 46) versus normal macula (n = 43) for arterioles (all identifiable) and venules (40/46 and 39/43 identifiable). All participants were aged ≥50 years without diabetes mellitus, hypertension, or other systemic vascular disease. Results: Intra- and inter-grader agreement was good-to-excellent for all en face OCT measurements of arteriole and venule diameters (intraclass correlation coefficient = 0.87 to 0.99). Arteriolar outer diameters (82.3 ± 19.8 µm vs 73.8 ± 16.1 µm; p < 0.05) and inner diameters (35.1 ± 8.4 µm vs 31.5 ± 8.1 µm; p < 0.05) were significantly greater in AMD eyes compared to normal eyes. Venular inner diameter was significantly greater (43.1 ± 9.5 µm vs 39.2 ± 10.1 µm; p < 0.05), but outer diameter remained unchanged (p = 0.17) in AMD eyes compared to normal eyes. Conclusion: Arteriolar dilation and altered venular inner diameter were observed in intermediate AMD eyes. These results support further investigation of vascular contributions to AMD in the early stages of disease, possibly using the en face OCT imaging modality. [ABSTRACT FROM AUTHOR]

Continuous-flow left ventricular assist device (cfLVAD) use is effective in supporting patients with end-stage heart failure (ESHF). Reduced flow pulsatility within the systemic circulation in cfLVAD-supported patients may lead to alterations within the microcirculation. Temporal changes in microvasculature in relation to adverse events in cfLVAD-supported patients have not been studied. We aimed to profile changes within retinal microvasculature and its association with adverse events. Retinal photography was performed using Topcon TRC-NW8 nonmydriatic fundus camera in cfLVAD-supported patients and ESHF control patients. Specific retinal measurements were evaluated using a validated semiautomated program. Demographic and adverse event data were documented. Forty-eight patients were studied (n = 29 cfLVAD, n = 19 ESHF). There were significant trends in retinal arteriolar caliber (B = −0.53 µm, 95% confidence interval [CI]: −0.96 to −0.10, p = 0.016) and retinal fractal dimension parameters (B = 0.014, 95% CI: 0.001-0.002, p = 0.016) in linear mixed model regressions. Among cfLVAD patients, there was a significant association between the incidence of gastrointestinal bleeding and stepwise increases in retinal arteriolar-venular caliber ratio (hazard ratio: 3.03, 95% CI: 2.06-4.45, p = 0.005), a measure of arteriolar narrowing. We have observed for the first time that alterations in retinal microvasculature in cfLVAD-supported patients may be associated with gastrointestinal bleeding. While understanding these temporal changes may predict future adverse events in cfLVAD-supported patients, further multicenter studies are required to confirm the associations observed. [ABSTRACT FROM AUTHOR]

Abstract Background Low-density lipoprotein cholesterol (LDL-C) is acknowledged as an independent risk factor (IRF) for atherosclerotic cardiovascular disease. Nevertheless, studies on the impact of LDL-C on microvasculature are still scarce. The retina, abundant in microvasculature, can now be examined for microvascular alterations through the novel, non-invasive, and quantitative optical coherence tomography angiography (OCTA) technique. Methods In this cross-sectional study, 243 patients from the geriatric department were recruited (between December 2022 and December 2023). Individuals were classified into four groups based on their LDL-C levels: Group 1 (≤ 1.8 mmol/L), Group 2 (> 1.8 mmol/L to ≤ 2.6 mmol/L), Group 3 (> 2.6 mmol/L to ≤ 3.4 mmol/L), and Group 4 (> 3.4 mmol/L). The OCTA results including retinal vessel density (VD), foveal avascular zone (FAZ) area, macula thickness, and retinal nerve fiber layer (RNFL) thickness were contrasted across these groups. T-tests, analysis of variance, Welch’s tests, or rank-sum tests were employed for statistical comparisons. In cases where significant differences between groups were found, post-hoc multiple comparisons or rank-sum tests were performed for pairwise group comparisons. Spearman’s correlation coefficient was employed to perform bivariate correlation analysis to evaluate the relationship between LDL-C levels and various OCTA measurements. Multivariable regression analysis was used to evaluate the association between LDL-C levels and various OCTA measurements. Linear regression analysis or mixed-effects linear models were applied. Results It was discovered that individuals with LDL-C levels exceeding 2.6 mmol/L (Groups 3 and 4) exhibited reduced VD in the retina, encompassing both the optic disc and macular regions, compared to those with LDL-C levels at or below 2.6 mmol/L (Groups 1 and 2). A negative correlation among LDL-C levels and retinal VD was identified, with r values spanning from − 0.228 to -0.385. Further regression analysis presented β values between − 0.954 and − 2.378. Additionally, no notable disparities were detected among the groups regarding FAZ area, macular thickness, and RNFL thickness. Conclusions The outcomes of this study suggest that elevated LDL-C levels constitute an IRF for decreased VD across the entire retina. Trial registration NCT05644548, December 1, 2022.

Abstract Purpose To investigate the changes in retinal vascular structures associated with various stages of myopia by designing automated software based on an artificial intelligence model. Methods The study involved 1324 pediatric participants from the National Children’s Medical Center in China, and 2366 high-quality retinal images and corresponding refractive parameters were obtained and analyzed. Spherical equivalent refraction (SER) degree was calculated. We proposed a data analysis model based on a combination of the Convolutional Neural Networks (CNN) model and the attention module to classify images, segment vascular structures, and measure vascular parameters, such as main angle (MA), branching angle (BA), bifurcation edge angle (BEA) and bifurcation edge coefficient (BEC). One-way ANOVA compared parameter measurements between the normal fundus, low myopia, moderate myopia, and high myopia groups. Results The mean age was 9.85 ± 2.60 years, with an average SER of -1.49 ± 3.16D in the right eye and − 1.48 ± 3.13D in the left eye. There were 279 (12.38%) images in the normal group and 384 (16.23%) images in the high myopia group. Compared with normal fundus, the MA of fundus vessels in different myopic refractive groups was significantly reduced (P = 0.006, P = 0.004, P = 0.019, respectively), and the performance of the venous system was particularly obvious (P

The segmentation of retinal vessels is vital for timely diagnosis. and treatment of various eye diseases. However, due to inherent characteristics of retinal vessels in fundus images such as changes in thickness, direction, and complexity of vessels, as well as imbalanced contrast between background and vessels, segmenting retinal vessels continues to pose significant challenges. Also, despite advancements in CNNbased methods, challenges such as insufficient extraction of structural information, complexity, overfitting, preference for local information, and poor performance in noisy conditions persist. To address these drawbacks, in this paper we proposed a novel modified U-Net named DABT-U-Net. Our method enhances discriminative capability by introducing Hierarchical Dilated Convolution (HDC), Dual Attentive BConvLSTM, and Multi-Head Self-Attention (MHSA) blocks. Additionally, we adopt a collaborative patch-based training approach to mitigate data scarcity and overfitting. Evaluation on the DRIVE and STARE datasets shows that DABT-U-Net achieves superior accuracy, sensitivity, and F1 score compared to existing methods, demonstrating its effectiveness in retinal vessel segmentation. Specifically, our proposed method demonstrates improvements in accuracy, sensitivity, and F1 score by 0.32%, 0.61%, and 0.14%, respectively, on the DRIVE dataset, and by 0.07%, 0.83%, and 0.14% on the STARE dataset compared to a less effective approach. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the changes in retinal vascular structures associated with various stages of myopia by designing automated software based on an artificial intelligence model. Methods: The study involved 1324 pediatric participants from the National Children's Medical Center in China, and 2366 high-quality retinal images and corresponding refractive parameters were obtained and analyzed. Spherical equivalent refraction (SER) degree was calculated. We proposed a data analysis model based on a combination of the Convolutional Neural Networks (CNN) model and the attention module to classify images, segment vascular structures, and measure vascular parameters, such as main angle (MA), branching angle (BA), bifurcation edge angle (BEA) and bifurcation edge coefficient (BEC). One-way ANOVA compared parameter measurements between the normal fundus, low myopia, moderate myopia, and high myopia groups. Results: The mean age was 9.85 ± 2.60 years, with an average SER of -1.49 ± 3.16D in the right eye and − 1.48 ± 3.13D in the left eye. There were 279 (12.38%) images in the normal group and 384 (16.23%) images in the high myopia group. Compared with normal fundus, the MA of fundus vessels in different myopic refractive groups was significantly reduced (P = 0.006, P = 0.004, P = 0.019, respectively), and the performance of the venous system was particularly obvious (P < 0.001). At the same time, the BEC decreased disproportionately (P < 0.001). Further analysis of fundus vascular parameters at different degrees of myopia showed that there were also significant differences in BA and branching coefficient (BC). The arterial BA value of the fundus vessel in the high myopia group was lower than that of other groups (P = 0.032, 95% confidence interval [CI], 0.22–4.86), while the venous BA values increased (P = 0.026). The BEC values of high myopia were higher than those of low and moderate myopia groups. When the loss function of our data classification model converged to 0.09, the model accuracy reached 94.19%. Conclusion: The progression of myopia is associated with a series of quantitative retinal vascular parameters, particularly the vascular angles. As the degree of myopia increases, the diversity of vascular characteristics represented by these parameters also increases. [ABSTRACT FROM AUTHOR]

Background: Low-density lipoprotein cholesterol (LDL-C) is acknowledged as an independent risk factor (IRF) for atherosclerotic cardiovascular disease. Nevertheless, studies on the impact of LDL-C on microvasculature are still scarce. The retina, abundant in microvasculature, can now be examined for microvascular alterations through the novel, non-invasive, and quantitative optical coherence tomography angiography (OCTA) technique. Methods: In this cross-sectional study, 243 patients from the geriatric department were recruited (between December 2022 and December 2023). Individuals were classified into four groups based on their LDL-C levels: Group 1 (≤ 1.8 mmol/L), Group 2 (> 1.8 mmol/L to ≤ 2.6 mmol/L), Group 3 (> 2.6 mmol/L to ≤ 3.4 mmol/L), and Group 4 (> 3.4 mmol/L). The OCTA results including retinal vessel density (VD), foveal avascular zone (FAZ) area, macula thickness, and retinal nerve fiber layer (RNFL) thickness were contrasted across these groups. T-tests, analysis of variance, Welch's tests, or rank-sum tests were employed for statistical comparisons. In cases where significant differences between groups were found, post-hoc multiple comparisons or rank-sum tests were performed for pairwise group comparisons. Spearman's correlation coefficient was employed to perform bivariate correlation analysis to evaluate the relationship between LDL-C levels and various OCTA measurements. Multivariable regression analysis was used to evaluate the association between LDL-C levels and various OCTA measurements. Linear regression analysis or mixed-effects linear models were applied. Results: It was discovered that individuals with LDL-C levels exceeding 2.6 mmol/L (Groups 3 and 4) exhibited reduced VD in the retina, encompassing both the optic disc and macular regions, compared to those with LDL-C levels at or below 2.6 mmol/L (Groups 1 and 2). A negative correlation among LDL-C levels and retinal VD was identified, with r values spanning from − 0.228 to -0.385. Further regression analysis presented β values between − 0.954 and − 2.378. Additionally, no notable disparities were detected among the groups regarding FAZ area, macular thickness, and RNFL thickness. Conclusions: The outcomes of this study suggest that elevated LDL-C levels constitute an IRF for decreased VD across the entire retina. Trial registration: NCT05644548, December 1, 2022. [ABSTRACT FROM AUTHOR]

A major hurdle to therapeutic development in cerebral small vessel diseases is the lack of in-vivo method that can be used repeatedly for evaluating directly cerebral microvessels. We hypothesised that Adaptive Optics (AO), which allows resolution images up to 1–2 μm/pixel at retinal level, could provide a biomarker for monitoring vascular changes in CADASIL, a genetic form of such condition. In 98 patients and 35 healthy individuals, the wall to lumen ratio (WLR), outer and inner diameter, wall thickness and wall cross-sectional area were measured in a parapapillary and/or paramacular retinal artery. The ratio of vessel diameters before and after light flicker stimulations was also calculated to measure vasoreactivity (VR). Multivariate mixed-model analysis showed that WLR was increased and associated with a larger wall thickness and smaller internal diameter of retinal arteries in patients. The difference was maximal at the youngest age and gradually reduced with aging. Average VR in patients was less than half of that of controls since the youngest age. Any robust association was found with clinical or imaging manifestations of the disease. Thus, AO enables the detection of early functional or structural vascular alterations in CADASIL but with no obvious link to the clinical or imaging severity. [ABSTRACT FROM AUTHOR]

Abstract Background The 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. Methods This 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. Results RC 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). Conclusions RC 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.

Abstract Introduction To analyze the correlation between orbital compliance and retinal vessel density (VD) based on dynamic Scheimpflug analyzer (Corvis ST) and optical coherence tomographic angiography (OCT-A). Methods In this prospective observational study, 65 eyes of 44 patients with thyroid-associated ophthalmopathy (TAO) in quiescent stage were included (15 males and 29 females). The whole eye movement (WEM) was detected by Corvis ST. The superficial capillary plexus VD (SCP-VD) and deep capillary plexus VD (DCP-VD) were obtained by scanning the 3 × 3 mm area around the fovea using OCT-A, while the peripapillary vessel density (ppVD) was obtained by scanning the 4.5 × 4.5 mm area around the optic disk. Covariances including biomechanically corrected intraocular pressure (bIOP), axial length, age and gender were adjusted during data analysis. Results The mean WEM of the participants was 0.235 ± 0.066 mm. The mean SCP-VD and DCP-VD in whole image were 46.20% ± 3.77% and 50.51% ± 3.96%; the mean whole pp-VD was 49.75% ± 2.01%. WEM was positively correlated with SCP-VD (r = 0.327, p = 0.01) and the whole pp-VD (r = 0.394, p

Our eyesight does not remain the same throughout our lives. Certain diseases start affecting our vision with age, such as diabetic retinopathy, hypertension, and glaucoma. This has varied effects on the structure of the retinal blood vessels. Therefore, studying these retinal blood vessels is vital for pre-diagnosis and diagnosing ophthalmic disease. Low contrast, complicated vessel structure, and inhomogeneous background lighting across subjects pose complex challenges in classifying vessels from retinal images. This paper proposes a cascade-supervised miniature U-Net (CSMi-UNet) to perform arteriovenous segmentation on Dual-Modal fundus images. The Dual-Modal contains monochrome images acquired at two different wavelengths (570 nm and 610 nm) based on hemoglobin absorption spectra, other than the regular RGB fundus images. Because of the high similarity in the arteriole and venule (AV) morphological structure, single modal (RGB) fundus images often result in misclassification. The AV structures are more detailed in the monochromic images and contribute significantly to arteriovenous analysis. The proposed CSMi-UNet utilizes the information with considerably fewer parameters and attains state-of-the-art performance, making it suitable for portable devices. We achieved an arteriovenous classification accuracy of 98.36%, F1-scores of 82.46%, and 82.53% for AV, significantly outperforming previous studies on the Dual-Modal dataset. [ABSTRACT FROM AUTHOR]

Objective: We aimed to characterize several aspects of retinal vascular dynamics in a patient with arrythmia in order to elicit additional diagnostic information on microvascular dysfunction. Methods: A 68‐year‐old male patient with arrythmia and an age‐ and gender‐matched control subject underwent ocular examination including dynamic retinal vessel assessment with flicker light provocation. Retinal vessel diameters were measured continuously following a standard protocol (IMEDOS Systems, Jena, Germany). The data were evaluated using methods of signal analysis. Results: Retinal vessel response following flicker provocation as well as local structural and functional behavior of retinal vessels were comparable between both individuals. The arrhythmia case demonstrated irregular arterial and venous heart rate (HR) pulsation with an average frequency of 1 Hz. Moreover, the case showed a higher magnitude and larger periods of low‐frequency retinal vessel oscillations as well as lower periodicity of both HR pulsations and low‐frequency vasomotions. Conclusions: Besides numerical examination of irregular HR pulsations in case of arrhythmia, from the direct noninvasive assessment of retinal vessel dynamics one can derive more detailed information on microvascular function including the whole spectrum of retinal arterial and venous pulsations and vasomotions. This may have implications for health screening not limited to atrial fibrillation. [ABSTRACT FROM AUTHOR]

Introduction: To analyze the correlation between orbital compliance and retinal vessel density (VD) based on dynamic Scheimpflug analyzer (Corvis ST) and optical coherence tomographic angiography (OCT-A). Methods: In this prospective observational study, 65 eyes of 44 patients with thyroid-associated ophthalmopathy (TAO) in quiescent stage were included (15 males and 29 females). The whole eye movement (WEM) was detected by Corvis ST. The superficial capillary plexus VD (SCP-VD) and deep capillary plexus VD (DCP-VD) were obtained by scanning the 3 × 3 mm area around the fovea using OCT-A, while the peripapillary vessel density (ppVD) was obtained by scanning the 4.5 × 4.5 mm area around the optic disk. Covariances including biomechanically corrected intraocular pressure (bIOP), axial length, age and gender were adjusted during data analysis. Results: The mean WEM of the participants was 0.235 ± 0.066 mm. The mean SCP-VD and DCP-VD in whole image were 46.20% ± 3.77% and 50.51% ± 3.96%; the mean whole pp-VD was 49.75% ± 2.01%. WEM was positively correlated with SCP-VD (r = 0.327, p = 0.01) and the whole pp-VD (r = 0.394, p < 0.01) after adjusting by gender, axial length (AL), age and bIOP, but it was not significantly correlated with DCP-VD (r = 0.072 p = 0.581). Conclusion: Increase in orbital pressure might reduce retinal microvascular perfusion. Our data suggest orbital mechanical compression may be an important cause of retinal VD changes in quiescent patients with TAO. [ABSTRACT FROM AUTHOR]

Keratoconus (KC) is the most common corneal ectasia. Optical coherence tomography angiography (OCT-A) is a relatively new non-invasive imaging technique that allows the visualization and quantification of retinal and choriocapillary blood vessels. The aim of this study is to assess retinal and choriocapillary vessel density (VD) differences between KC patients and healthy controls and to investigate correlations between VD and KC severity. Fifty-two eyes were included in this exploratory study: twenty-six eyes from 26 KC patients and twenty-six eyes from 26 age- and gender-matched healthy controls. All patients underwent Scheimpflug corneal topography with Pentacam, axis lengths measurement and optical coherence tomography angiography (OCT-A). The thinnest spot in corneal pachymetry, maximum K (Kmax) and KC severity indices from the Belin/Ambrósio enhanced ectasia display (BAD) were also assessed. There was a distinct reduction particularly in the retinal VD of the superficial capillary plexus (SCP). Correlation analyses showed strong and moderate negative correlations between the VD in the macular SCP and BAD KC scores and between the SCP VD and Kmax. There was no difference in retinal thickness between the KC and healthy controls. With this study, further evidence for altered VD measurements by OCT-A in KC patients is given. For the first time, we demonstrated negative correlations between BAD KC scores and retinal blood vessel alterations. A major limitation of the study is the relatively small sample size. Since an artefactual reduction of the quantitative OCT-A measurements due to irregular corneal topography in KC must be assumed, it remains to be investigated whether there are also actual changes in the retinal microcirculation in KC. [ABSTRACT FROM AUTHOR]

Aim of the study: To study the peculiarities of retinal changes’ structure and frequency according to fundoscopy data in patients with different clinical course of COVID-19. Material and methods: This was prospective, uncontrolled crosssectional study. A total of 117 patients (234 eyes) with varying severity of COVID-19 clinical course were divided into groups: 1) an extremely severe course; 2) a severe course; 3) moderate severity with decompensated accompanying pathology; 4) moderate severity with compensated concomitant pathology. Registration of patients’ eye fundus with the portable fundus camera Pictor Plus Fundus Camera and VistaView (Volk Optical). Results: Cotton wool spots, narrowed retinal vessels, central retinal vein occlusion (CRVO) (8.8%), petechial and intraretinal hemorrhages (23.5%), tortuosity and dilatation of retinal venules (11.8%), prethrombosis of the central retinal vein (CRV) (a state determined by venous blood stasis, characterized by dilated appearance of the eye fundus veins, their dark color, curved structure, optic nerve edema) (2.9%) and vitreous hemorrhage (5.9%) were found in 1st group patients; in 29.4% of cases there were no retinal changes. Retinal changes were absent in 59.3% in 4th group patients and in 86.7% in 3rd group patients; no clinically significant retinal changes were detected in these patients. Conclusions: Retinal changes’ structure and frequency in patients with COVID-19 correlate with the severity of its clinical course. Within 1st group patients cotton wool spots, narrowed retinal vessels, petechial and intraretinal hemorrhages, thrombosis/prethrombosis of CRV, tortuosity and dilatation of retinal venules, and vitreous hemorrhage are diagnosed, which is significantly more common than in patients of 3rd and 4th groups (p < 0.05). A trend of decreasing risk of clinically significant retinal changes (thrombosis/ prethrombosis of CRV) and vitreous hemorrhage with decreasing severity of the disease was observed. [ABSTRACT FROM AUTHOR]

Background: The 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. Methods: This 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. Results: RC 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). Conclusions: RC 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. [ABSTRACT FROM AUTHOR]

Several ocular and cardiovascular disorders are characterized by an elevated tortuosity of retinal blood vessels. Objective tortuosity measurements can be obtained through the computation of a set of tortuosity indices derived from digital image analysis of an eye fundus image. These calculations require the parametrization of the vessel path traced in the image. As a vessel descriptor, tortuosity should be independent of scale, but this property demands thorough examination and assessment for each index. We investigate the impact of altering image resolution on the local tortuosity indices of retinal vessels. [ABSTRACT FROM AUTHOR]

AIM: To evaluate the predictive value of superficial retinal capillary plexus (SRCP) and radial peripapillary capillary (RPC) for visual field recovery after optic cross decompression and compare them with peripapillary nerve fiber layer (pRNFL) and ganglion cell complex (GCC). METHODS: This prospective longitudinal observational study included patients with chiasmal compression due to sellar region mass scheduled for decompressive surgery. Generalized estimating equations were used to compare retinal vessel density and retinal layer thickness pre- and post-operatively and with healthy controls. Logistic regression models were used to assess the relationship between preoperative GCC, pRNFL, SRCP, and RPC parameters and visual field recovery after surgery. RESULTS: The study included 43 eyes of 24 patients and 48 eyes of 24 healthy controls. Preoperative RPC and SRCP vessel density and pRNFL and GCC thickness were lower than healthy controls and higher than postoperative values. The best predictive GCC and pRNFL models were based on the superior GCC [area under the curve (AUC)=0.866] and the tempo-inferior pRNFL (AUC=0.824), and the best predictive SRCP and RPC models were based on the nasal SRCP (AUC=0.718) and tempo-inferior RPC (AUC=0.825). There was no statistical difference in the predictive value of the superior GCC, tempo-inferior pRNFL, and tempo-inferior RPC (all P>0.05). CONCLUSION: Compression of the optic chiasm by tumors in the saddle area can reduce retinal thickness and blood perfusion. This reduction persists despite the recovery of the visual field after decompression surgery. GCC, pRNFL, and RPC can be used as sensitive predictors of visual field recovery after decompression surgery.

PurposeTo investigate age-dependent wall to lumen ratio (WLR) reference values for healthy individuals in adaptive optics imaging (AO). WLR serves as an objective, dimensionless parameter for the evaluation of structural changes in vessels caused by conditions like arterial hypertension, diabetes or vascular stenosis.Methods50 right eyes of healthy individuals were examined by adaptive optics imaging. The central big arterioles and smaller arterial branches at least one disc diameter away from the optic disc, approximately above or below the macula were measured by the manufacturer’s software. The wall-lumen-ratio (WLR), the wall cross-sectional area (WCSA) and lumen diameter (LD) were assessed. Subsequent data analysis was performed with a focus on variables including age, gender and blood pressure.ResultsNormative values for WLR, WCSA and LD in 5 different age groups could be established. However, no significant differences between the age groups were found. Intra-subject comparisons revealed significantly higher WLRs on peripheral branches when compared to central arterioles. WLR showed in this normotensive cohort no relevant correlation with the systolic, diastolic and mean blood pressure. Gender and intraocular pressure had no influence on the vascular parameters.ConclusionAO is capable of examining vascular alterations in arterioles at an almost microscopic level. Age did not seem to alter WLR, normotensive blood pressure parameters showed also no significant impact. AO-based vessel analysis may provide clinically useful biomarkers for cardiovascular health and should be tested in future studies.

Copyright of Arquivos Brasileiros de Oftalmologia is the property of Arquivos Brasileiros de Oftalmologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: To explore the effect of the flavonoid compounds of Andrographis paniculata by evaluating the glycemic profile, oxidative process, and inflammatory values in rats with diabetic retinopathy (DR). Methods: An extract of A. paniculata was macerated with ethanol which yielded flavonoid compounds. Streptozotocin was utilized to induce diabetes mellitus in male Wistar rats. Vucetic's methods were used to evaluate the retinal vessel diameters. Antioxidant parameters and inflammatory cytokines were assessed in retinal tissue. Results: A funduscopic examination revealed some alterations in the retinal veins. In comparison to the DR group with no treatment, the diameter of the retinal vessels in the DR group that was treated with the flavonoid component of the A. paniculata extract (FAP) at doses of 20 and 40 mg/kg body weight (BW) was significantly smaller (P <0.05). The DR treatment groups administered with FAP at doses of 20 and 40 mg/kg BW had a greater ability to reduce TNF-alpha and VEGF levels as compared to the DR rats without treatment (P < 0.05), Glutathione, superoxide dismutase (SOD), and catalase levels were increased after receiving FAP at doses of 20 and 40 mg/kg BW (P <0.05). Conclusion: Administration of doses of 20 and 40 mg/kg BW of the A. paniculata's flavonoid compounds improved DR in rats via retinal vessel diameter reduction, TNF-and VEGF level reduction, and increasing antioxidants, SOD, catalase, and glutathione. [ABSTRACT FROM AUTHOR]

Background: Lupus retinopathy, an ocular manifestation of systemic lupus erythematosus (SLE), is the major pathology attributed to retinal vasculopathy. Our study is to analyze the changes in retinal vessels in patients with SLE by optical coherence tomography angiography. Methods: A total of 61 SLE patients without obvious retinal manifestation and 71 healthy people were included. The SLE patients were further divided into a lupus nephritis (LN) group and a non-LN group. The changes in central macular thickness (CMT) and the retinal vessel densities were compared between the two groups, and the correlation between retinal vascular changes and disease activity was analyzed. Results: Compared with healthy control, the CMT and the retinal vascular densities in both superficial and deep retina were decreased significantly in SLE patients. There was no significant difference in retinal vascular densities between LN groups and non-LN groups. Conclusion: The CMT and retinal vessel densities were decreased in SLE patients without clinical manifestations, which might serve as a sensitive biomarker for early changes of lupus retinopathy in SLE patients. [ABSTRACT FROM AUTHOR]

The small retinal vessels reflect cerebral microcirculation and its fractal dimension (D f), representing the complexity of the retinal microcirculation. However, the connection between retinal circulation and cognitive function lacked consistent and longitudinal evidence. This study aimed to explore the association between retinal vascular complexity and cognitive impairment over time in non-demented community-dwelling older adults. This four-year prospective cohort study (2015–2019) is part of the ongoing Taiwan Initiative for Geriatric Epidemiological Research (TIGER, 2011 to present). Of the 434 older adults (age >65) recruited, 207 participants were included for analysis. The retinal vascular D f was assessed by baseline images from fundus photography (2015–2017). Global (Montreal Cognitive Assessment-Taiwanese version, MoCA-T) and domain-specific cognition were assessed at the baseline and 2-year follow-up (2017–2019). The multivariable linear regression models and generalized linear mixed models were used to evaluate the association of D f with cognitive decline/impairment over time. Decreased left retinal vascular complexity was associated with poor attention performance (β = −0.40). As follow-up time increased, decreased vascular complexity was associated with poor memory performance (right: β = −0.25; left: β = −0.19), and decreased right vascular complexity was associated with poor attention performance (β = −0.18). Low retinal vascular complexity of the right or left eye may be differentially associated with cognitive domains in community-dwelling older adults over two years. The retinal vascular D f of either eye may be served as a screening tool for detecting cognitive impairment in the preclinical phase of dementia. [ABSTRACT FROM AUTHOR]

Simple Summary: This study explored how retinal vasculature changes during central hypovolemia induced by lower body negative pressure (LBNP). LBNP is known to shift blood to the lower body and is routinely employed to assess the effects of central hypovolemia and/or to simulate the effects of hemorrhage on systems physiology. In this study, retinal imaging was carried out in participants of both sexes as they underwent LBNP. Surprisingly, no significant changes were observed in retinal blood flow between time points or across the sexes. This study is the first in this field, shedding light on retinal response during a moderate LBNP of −40 mmHg, which induces fluid shifts and evokes systematic physiological responses like those that occur during upright standing. However, further research is needed with stronger LBNP levels, including those that can induce pre-fainting (presyncope) states, to fully understand how retinal microcirculation adapts during complete cardiovascular collapse (e.g., during hypovolemic shock) and/or during severe hemorrhage. Introduction: Lower body negative pressure (LBNP) is routinely used to induce central hypovolemia. LBNP leads to a shift in blood to the lower extremities. While the effects of LBNP on physiological responses and large arteries have been widely reported, there is almost no literature regarding how these cephalad fluid shifts affect the microvasculature. The present study evaluated the changes in retinal microcirculation parameters induced by LBNP in both males and females. Methodology: Forty-four participants were recruited for the present study. The retinal measurements were performed at six time points during the LBNP protocol. To prevent the development of cardiovascular collapse (syncope) in the healthy participants, graded LBNP until a maximum of −40 mmHg was applied. A non-mydriatic, hand-held Optomed Aurora retinal camera was used to capture the retinal images. MONA Reva software (version 2.1.1) was used to analyze the central retinal arterial and venous diameter changes during the LBNP application. Repeated measures ANOVAs, including sex as the between-subjects factor and the grade of the LBNP as the within-subjects factor, were performed. Results: No significant changes in retinal microcirculation were observed between the evaluated time points or across the sexes. Conclusions: Graded LBNP application did not lead to changes in the retinal microvasculature across the sexes. The present study is the first in the given area that attempted to capture the changes in retinal microcirculation caused by central hypovolemia during LBNP. However, further research is needed with higher LBNP levels, including those that can induce pre-fainting (presyncope), to fully understand how retinal microcirculation adapts during complete cardiovascular collapse (e.g., during hypovolemic shock) and/or during severe hemorrhage. [ABSTRACT FROM AUTHOR]

Copyright of Arquivos Brasileiros de Oftalmologia is the property of Arquivos Brasileiros de Oftalmologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AIM: To measure the retinal vessels of primary open angle glaucoma (POAG) patients on spectral domain optical coherence tomography (SD-OCT) with a full-width at half-maximum (FWHM) algorithm to better explore their structural changes in the pathogenesis of POAG. METHODS: In this retrospective case-control study, the right eyes of 32 patients with POAG and 30 healthy individuals were routinely selected. Images of the supratemporal and infratemporal retinal vessels in the B zones were obtained by SD-OCT, and the edges of the vessels were identified by the FWHM method. The internal and external diameters, wall thickness (WT), wall cross-sectional area (WCSA) and wall-to-lumen ratio (WLR) of the blood vessels were studied. RESULTS: Compared with the healthy control group, the POAG group showed a significantly reduced retinal arteriolar outer diameter (RAOD), retinal arteriolar lumen diameter (RALD) and WSCA in the supratemporal (124.22±12.42 vs 138.32±10.73 µm, 96.09±11.09 vs 108.53±9.89 µm, and 4762.02±913.51 vs 5785.75±1148.28 µm2, respectively, all P

Automatic and fast segmentation of retinal vessels in fundus images is a prerequisite in clinical ophthalmic diseases; however, the high model complexity and low segmentation accuracy still limit its application. This paper proposes a lightweight dual-path cascaded network (LDPC-Net) for automatic and fast vessel segmentation. We designed a dual-path cascaded network via two U-shaped structures. Firstly, we employed a structured discarding (SD) convolution module to alleviate the over-fitting problem in both codec parts. Secondly, we introduced the depthwise separable convolution (DSC) technique to reduce the parameter amount of the model. Thirdly, a residual atrous spatial pyramid pooling (ResASPP) model is constructed in the connection layer to aggregate multi-scale information effectively. Finally, we performed comparative experiments on three public datasets. Experimental results show that the proposed method achieved superior performance on the accuracy, connectivity, and parameter quantity, thus proving that it can be a promising lightweight assisted tool for ophthalmic diseases.

Adaptive optics (AO) provides new, unique opportunities for in vivo visualization of retinal vasculature. AO retinal vessel imaging can be utilized as a component of multimodal imaging tools to complement conventional diagnostic imaging modalities. Non-invasive and highly promising AO imaging of fundus structures allows the qualitative and quantitative assessment of early signs of retinal vascular remodeling associated with age, arterial hypertension, diabetes mellitus and other disorders.

With the rapid advancements in artificial intelligence, particularly in machine learning and deep learning, automated disease diagnosis is becoming increasingly feasible. Generating larger databases is crucial for training and validating the performance of models for chronic diseases such as glaucoma and diabetic retinopathy, which progress slowly and unnoticed. Automated procedures for retinal vessel segmentation and optic cup/disk localization are preferred for large-scale screening of the public, contributing to the early detection and treatment of eye diseases, preventing blindness, and improving public health. This paper focuses on the challenges involved in segmenting the retinal vessels from fundus images and presents a modified ColonSegNet model for retinal vessel segmentation that includes efficient methods for locating the true vessels and applies data augmentation to overcome the issue of fewer graded images. The paper uses the optimal values for the contrast enhancement of retinal fundus images using intelligent evolution algorithms. The central vessel reflex, bifurcation, crossover, thin vessels, and lesion presence are highlighted as significant challenges in retinal vessel segmentation. The proposed method achieves high sensitivity, specificity, and accuracy, {0.839, 0.979, 0.966}, {0.865, 0.979, 0.971}, and {0.867, 0.981, 0.972}, segmenting retinal vessels on DRIVE, CHASE_DB, and STARE. The work is crucial in developing automated systems for the early detection and treatment of eye diseases, thereby improving public health.

Retinal images are found as the major resources for the automatic diagnosis of diabetic retinopathy (DR). However, the advanced stages like proliferative diabetic retinopathy (PDR) cause the branch out of new and thin vessels in the retina. These vessels create a lot of confusion at the diagnosis of DR through retinal mages. Hence, this paper proposes a new blood vessels segmentation mechanism in three stages; they are major blood vessels segmentation, minor blood vessels segmentation and post-processing. In the first stage, the retinal image is enhanced for quality enhancement followed low pass filtering and top-hat transform to segment major blood vessels. In the second stage, the residue image left in the first stage is processed for pixel level classification. At this stage, each pixel is represented with a set of 19 features. Then this feature vector is fed to support vector machine (SVM) for classification. Finally, the resultant images obtained in the first two stages are combined to get the final retinal vessel structure. For simulation, we used two standard retinal image datasets namely STARE and CHASE_DB and the performance is measured through sensitivity, accuracy, specificity, Jaccard Similarity index and Dice similarity index. Simulation results show that the proposed method achieved better segmentation accuracy and it is of approximately 96.85% and 96.66% for STARE and CHASE_DB respectively. [ABSTRACT FROM AUTHOR]

The healthcare burden of cardiovascular diseases remains a major issue worldwide. Understanding the underlying mechanisms and improving identification of people with a higher risk profile of systemic vascular disease through noninvasive examinations is crucial. In ophthalmology, retinal vascular network imaging is simple and noninvasive and can provide in vivo information of the microstructure and vascular health. For more than 10 years, different research teams have been working on developing software to enable automatic analysis of the retinal vascular network from different imaging techniques (retinal fundus photographs, OCT angiography, adaptive optics, etc.) and to provide a description of the geometric characteristics of its arterial and venous components. Thus, the structure of retinal vessels could be considered a witness of the systemic vascular status. A new approach called "oculomics" using retinal image datasets and artificial intelligence algorithms recently increased the interest in retinal microvascular biomarkers. Despite the large volume of associated research, the role of retinal biomarkers in the screening, monitoring, or prediction of systemic vascular disease remains uncertain. A PubMed search was conducted until August 2022 and yielded relevant peer-reviewed articles based on a set of inclusion criteria. This literature review is intended to summarize the state of the art in oculomics and cardiovascular disease research. [ABSTRACT FROM AUTHOR]

Background: Both greater retinal neurodegenerative pathology and greater cardiovascular burden are seen in people with multiple sclerosis (pwMS). Studies also describe multiple extracranial and intracranial vascular changes in pwMS. However, there have been few studies examining the neuroretinal vasculature in MS. Our aim is to determine differences in retinal vasculature between pwMS and healthy controls (HCs) and to determine the relationship between retinal nerve fiber layer (RNFL) thickness and retinal vasculature characteristics. Methods: A total of 167 pwMS and 48 HCs were scanned using optical coherence tomography (OCT). Earlier OCT scans were available for 101 pwMS and 35 HCs for an additional longitudinal analysis. Segmentation of retinal vasculature was performed in a blinded manner in MATLAB's optical coherence tomography segmentation and evaluation GUI (OCTSEG) software. Results: PwMS has fewer retinal blood vessels when compared to HCs (35.1 vs. 36.8, p = 0.017). Over the 5.4 year follow up, and when compared to HCs, pwMS has a significant decrease in number of retinal vessels (average loss of −3.7 p = 0.007). Moreover, the total vessel diameter in pwMS does not change when compared to the increase in vessel diameter in the HCs (0.06 vs. 0.3, p = 0.017). Only in pwMS is there an association between lower RNFL thickness and fewer retinal vessel number and smaller diameter (r = 0.191, p = 0.018 and r = 0.216, p = 0.007). Conclusions: Over 5 years, pwMS exhibit significant retinal vascular changes that are related to greater atrophy of the retinal layers. [ABSTRACT FROM AUTHOR]

Neurodegeneration and cognitive decline in aging are growing public health concerns. This study investigates associations between central retinal arteriolar and venular equivalents (CRAE, CRVE) and brain-aging, a sensory and cognitive test composite measure, and macular ganglion cell-inner plexiform layer (mGCIPL) thickness, a biomarker of neurodegeneration. Beaver Dam Offspring Study (BOSS) participants are adult children (baseline (2005–2008) age 21–84 years) of the population-based Epidemiology of Hearing Loss Study participants. Follow-up occurred every 5 years. In 2010–2013, fundus photographs were used to measure retinal vessels. A brain-aging score was constructed by principal component analysis using sensorineural and cognitive data. Associations between incident brain-aging and vessel measures were investigated using logistic regression. Associations between CRAE and CRVE and mGCIPL thickness, measured in 2015–2017, were also investigated. Participants (N = 2381; mean age: 53.9 years (SD = 9.8); 54% women) had a mean CRAE and CRVE of 148.8 µm (SD = 14.5) and 221.7 µm (SD = 20.7), respectively. Among those without ocular conditions, wider CRAE was associated with decreased 5-year brain-aging risk (33% per SD CRAE increase). Both vessel measures were independently associated with mGCIPL thickness. The mGCIPL thickness increased by approximately 1.7 µm and 2.0 µm per SD increase in CRAE and CRVE, respectively. The association of CRAE with incident brain-aging indicates its potential use as a screening tool among those without eye disease. The associations between CRAE and CRVE and mGCIPL thickness indicate narrower vasculature could affect neuronal health. These associations point to potential usefulness of retinal vessel measurements to identify people at higher risk of sensorineural declines and neurodegeneration. [ABSTRACT FROM AUTHOR]

Detection of curvilinear structures from microscopic images, which help the clinicians to make an unambiguous diagnosis is assuming paramount importance in recent clinical practice. Appearance and size of dermatophytic hyphae, keratitic fungi, corneal and retinal vessels vary widely making their automated detection cumbersome. Automated deep learning methods, endowed with superior self-learning capacity, have superseded the traditional machine learning methods, especially in complex images with challenging background. Automatic feature learning ability using large input data with better generalization and recognition capability, but devoid of human interference and excessive pre-processing, is highly beneficial in the above context. Varied attempts have been made by researchers to overcome challenges such as thin vessels, bifurcations and obstructive lesions in retinal vessel detection as revealed through several publications reviewed here. Revelations of diabetic neuropathic complications such as tortuosity, changes in the density and angles of the corneal fibers have been successfully sorted in many publications reviewed here. Since artifacts complicate the images and affect the quality of analysis, methods addressing these challenges have been described. Traditional and deep learning methods, that have been adapted and published between 2015 and 2021 covering retinal vessels, corneal nerves and filamentous fungi have been summarized in this review. We find several novel and meritorious ideas and techniques being put to use in the case of retinal vessel segmentation and classification, which by way of cross-domain adaptation can be utilized in the case of corneal and filamentous fungi also, making suitable adaptations to the challenges to be addressed. [ABSTRACT FROM AUTHOR]

Background: The connection between vascular and brain metrics is well-studied in older adults, but neglected in youth and in psychiatric populations at increased cardiovascular risk. We therefore examined the association of retinal vascular caliber with cerebral blood flow (CBF) in adolescents with and without bipolar disorder (BD).Methods: Ninety-four adolescents (n = 48 BD, n = 46 controls) completed retinal fundus imaging, yielding estimates of arteriolar and venular diameter. Arterial spin labelling MRI was performed to measure CBF. We tested for associations between retinal vascular caliber and CBF in regions of interest; anterior cingulate cortex (ACC), middle frontal gyrus, and hippocampus in BD and controls separately. Complementary voxel-wise analyses were also performed.Results: In the BD group, higher arteriovenous ratio (AVR) was associated with greater ACC CBF (β = 0.34, puncorrected = 0.02), after controlling for age, sex, and BMI, however this finding did not survive correction for multiple comparisons. The control group did not show any associations (β = 0.13, puncorrected = 0.40). Voxel-wise analyses within the BD group detected a significant positive association between AVR and regional CBF in two distinct clusters: i) left hippocampus (p < 0.0001); ii) right middle temporal gyrus (p = 0.04).Limitations: Limited sample size; young, medically healthy sample limits signal detection; cross-sectional design.Conclusion: This study reveals that higher AVR is associated with higher regional CBF in adolescents with BD. Present findings advance understanding of potential neurofunctional mechanisms linking retinal vascular caliber with psychiatric diagnoses. This proof-of-concept study was designed to generate initial insights to guide future studies focusing on the vascular-brain connection in youth and in psychiatry. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the acute effects of caffeine and glucose intake on retinal vascular calibre of healthy adults. Methods: This prospective crossover study was conducted at the Centre for Eye Research Australia (Melbourne, Australia). Standardized doses of 300 mg caffeine (approximately 3 cups coffee), 30 g glucose or 300 ml of water, were each given to 19 healthy subjects on separate days. Retinal photographs and blood pressure measurements were taken at baseline, 30-, 60- and 120-min after ingestion of each solution. Central retinal artery and vein equivalents (CRAE, CRVE) and the arterio-venule ratio were measured using computer-assisted software. The mean retinal vascular calibre measurements were compared between pre- and post-ingestion images. Results: After caffeine intake, significant reductions were observed in mean CRAE of − 9.3 μm, − 10.4 μm and − 8.5 μm and CRVE of − 16.9 μm, − 18.7 μm and − 16.1 μm at 30-, 60- and 120-min after intake when compared with baseline (p ≤ 0.002 for all; paired t test). No significant changes were observed in mean retinal vascular calibre measurements after intake of either glucose or water when compared to baseline (p ≥ 0.072 for all). When controlling for baseline characteristics and blood pressure measurements, only caffeine intake had a significant effect on reducing both CRAE and CRVE at all time points post ingestion (p ≤ 0.003 for all, multiple linear regression model). Conclusion: Caffeine is associated with an acute vasoconstrictive effect on retinal arterioles and venules in healthy subjects. Factors other than blood pressure-induced autoregulation play a significant role in caffeine-associated retinal vasoconstriction. [ABSTRACT FROM AUTHOR]

Aim Retinal vessel diameters are candidate biomarkers of mortality prediction in large population-based studies. We aimed to investigate the predictive value of retinal vessel diameters and flicker-induced retinal arteriolar and venular dilation on all-cause mortality in long-term follow-up of haemodialysis patients. Methods and results Retinal vessel diameters as well as maximum arteriolar (aMax) and venular dilation (vMax) were investigated in 275 and 214 haemodialysis patients, respectively. Patients were observed in a long-term follow-up for a median period of 73 months. About 36% (76/214) and 41% (113/275) of patients died. Arteriolar and venular diameters were 175 ± 19 and 208 ± 20 µm, respectively. Median aMax and vMax were 1.6 (0.3–3.3) and 3.2 (2.0–5.1)%. Patients within the lowest tertile of vMax showed lower 5-year survival rates compared with the highest tertile (50.6 vs. 82.1%) and also exhibited a higher incidence of infection-related deaths (21.7 vs. 4.0%). Univariate hazard ratio (HR) per standard deviation increase of vMax for all-cause mortality was 0.69 (0.54–0.88) and was even more pronounced for infection-related mortality [HR 0.53 (0.33–0.83)]. Regarding all-cause mortality, multivariate adjustment for eight non-retinal mortality predictors including interleukin-6 did not attenuate the HR relevantly [0.73 (0.54–0.98)]. Arteriolar and venular diameters did not predict all-cause nor cardiovascular and infection-related mortality. Conclusions Long-term follow-up of patients on haemodialysis demonstrated the potential of retinal venular dilation capacity for mortality prediction, which was most pronounced for infection-related mortality. In the same cohort, retinal arteriolar and venular diameters showed no predictive value for hard endpoints. Retinal venular dilation but not arteriolar and venular diameters is a valuable diagnostic biomarker for risk prediction in patients with end-stage renal disease and should be considered for monitoring of critically ill patients. [ABSTRACT FROM AUTHOR]

Automated detection of retinal structures, such as retinal vessels (RV), the foveal avascular zone (FAZ), and retinal vascular junctions (RVJ), are of great importance for understanding diseases of the eye and clinical decision-making. In this paper, we propose a novel Voting-based Adaptive Feature Fusion multi-task network (VAFF-Net) for joint segmentation, detection, and classification of RV, FAZ, and RVJ in optical coherence tomography angiography (OCTA). A task-specific voting gate module is proposed to adaptively extract and fuse different features for specific tasks at two levels: features at different spatial positions from a single encoder, and features from multiple encoders. In particular, since the complexity of the microvasculature in OCTA images makes simultaneous precise localization and classification of retinal vascular junctions into bifurcation/crossing a challenging task, we specifically design a task head by combining the heatmap regression and grid classification. We take advantage of three different en face angiograms from various retinal layers, rather than following existing methods that use only a single en face. We carry out extensive experiments on three OCTA datasets acquired using different imaging devices, and the results demonstrate that the proposed method performs on the whole better than either the state-of-the-art single-purpose methods or existing multi-task learning solutions. We also demonstrate that our multi-task learning method generalizes across other imaging modalities, such as color fundus photography, and may potentially be used as a general multi-task learning tool. We also construct three datasets for multiple structure detection, and part of these datasets with the source code and evaluation benchmark have been released for public access. [ABSTRACT FROM AUTHOR]

Convolutional neural networks have been widely applied to medical image segmentation and have achieved considerable performance. However, the performance may be significantly affected by the domain gap between training data (source domain) and testing data (target domain). To address this issue, we propose a data manipulation based domain generalization method, called Automated Augmentation for Domain Generalization (AADG). Our AADG framework can effectively sample data augmentation policies that generate novel domains and diversify the training set from an appropriate search space. Specifically, we introduce a novel proxy task maximizing the diversity among multiple augmented novel domains as measured by the Sinkhorn distance in a unit sphere space, making automated augmentation tractable. Adversarial training and deep reinforcement learning are employed to efficiently search the objectives. Quantitative and qualitative experiments on 11 publicly-accessible fundus image datasets (four for retinal vessel segmentation, four for optic disc and cup (OD/OC) segmentation and three for retinal lesion segmentation) are comprehensively performed. Two OCTA datasets for retinal vasculature segmentation are further involved to validate cross-modality generalization. Our proposed AADG exhibits state-of-the-art generalization performance and outperforms existing approaches by considerable margins on retinal vessel, OD/OC and lesion segmentation tasks. The learned policies are empirically validated to be model-agnostic and can transfer well to other models. The source code is available at https://github.com/CRazorback/AADG. [ABSTRACT FROM AUTHOR]

Purpose: Mice are highly used in retinal research because, like humans, mice have vascularized retinas and choroidal circulation. Although the retinal circulation has been well-characterized in development, its stability during adulthood is less understood. To examine this network, we quantified several key metrics of the trilaminar vasculature., Methods: We used mice (n = 15) with transgenic fluorescent NG2-DsRed (JX: #00824), a vascular-associated label in the retina. One eye per mouse was imaged using confocal microscopy (Nikon A1 Ti2 Eclipse) and traced with ImageJ SNT tools. Using an adaptive optics scanning light ophthalmoscope, additional mice (n = 3) were imaged at single-cell resolution within the living eye to measure the same vasculature., Results: Across mice, we found a stable retinal circulation that formed and maintained a trilaminar stratification throughout early adulthood at all eccentricities. Bridging these layers, microvessels had five distinct anatomical branching patterns. The superficial, intermediate, and deep plexuses increased in density with depth: 16.14 ± 3.61 mm/mm2, 22.14 ± 6.86 mm/mm2, and 31.01 ± 6.24 mm/mm2, respectively. This patterning was not impacted by eccentricity or age (13-61 weeks). Similar metrics were achieved using adaptive optics scanning light ophthalmoscope in vivo with the same analysis pipeline., Conclusions: The mouse retinal vasculature was stable up to 50 weeks of age, providing a robust and extensive baseline dataset with which models of retinal vascular and neural disease may be compared. Vessels connecting the laminae were more complex than previously reported and represented a uniquely vulnerable population due to their relatively low density.

Purpose: This review explores the role of pigment epithelium-derived factor (PEDF) in retinal degenerative and vascular disorders and assesses its potential both as an adjunct to established vascular endothelial growth factor inhibiting treatments for retinal vascular diseases and as a neuroprotective therapeutic agent., Methods: A comprehensive literature review was conducted, focusing on the neuroprotective and anti-angiogenic properties of PEDF. The review evaluated its effects on retinal health, its dysregulation in ocular disorders, and its therapeutic application in preclinical models. Advances in drug delivery, including gene therapy, were also examined., Results: PEDF, initially identified for promoting neuronal differentiation, is also a potent endogenous angiogenesis inhibitor. Strong anti-angiogenic and neuroprotective effects are observed in preclinical studies. It has pro-apoptotic and antiproliferative effects on endothelial cells thereby reducing neovascularization. Although promising, clinical development is limited with only a single conducted phase I clinical trial for macular neovascularization. Development of PEDF-derived peptides enhances potency and specificity, and emerging gene therapy approaches offer sustained PEDF expression for long-term treatment. However, questions regarding dosage, durability, and efficacy remain, particularly in large animal models., Conclusions: PEDF shows significant therapeutic potential in preclinical models of retinal degeneration and vascular disorders. Despite inconclusive evidence on PEDF downregulation as a primary disease driver, many studies highlight its therapeutic benefits and favorable safety profile. Advances in gene therapy could enable long-acting PEDF-based treatments, but further research is needed to optimize dosage and durability, potentially leading to clinical trials and expanding treatment options for retinal disorders.

Background and Aims: Endothelial dysfunction predicts elevated cardiovascular (CV) risk in healthy individuals. Aerobic exercise reduces endothelial dysfunction in part by improving CV risk factors. Yet, this explains less than 50 % of the effect and a direct influence of exercise training on the endothelium is discussed as possible contributor. The VascuFit study applied non-linear periodized aerobic exercise (NLPE) training to assess its multilevel effects on endothelial function including potential epigenetic endothelial modifications by circulating micro-ribonucleic acids (endomiRs)., Methods: Sedentary adults with elevated CV risk between 40 and 60 years were randomized 2:1 and engaged in an eight-week ergometer-based NLPE training (n = 30) or received standard exercise recommendations (n = 14). Macro-, microvascular, cellular and molecular adaptations were assessed via brachial-arterial flow-mediated dilation (baFMD), static retinal vessel analysis (SVA), flow cytometry, and endomiRs regulating key pathways of endothelial function. Statistics included ANCOVA, Principal Component Analysis (PCA), and regression analyses., Results: baFMD improved by 2.38 % (CI:0.70-4.06, p = 0.007) independent of CV risk, whereas SVA parameters and circulating endothelial (progenitor) cells did not significantly change in the NLPE group. The mean distance between baseline and follow-up PCA loadings of the endomiR dataset explaining 44.2 % of dataset variability was higher in the NLPE-group compared to the control group (2.71 ± 2.02 vs. 1.65 ± 0.93). However, regression analyses showed no evidence of endomiRs explaining the improvement of baFMD., Conclusions: The improvement of macrovascular endothelial function by aerobic exercise training was independent from CV risk factors. Increased heterogeneity among endomiRs did not explain this effect, but suggests an adaptive response to the exercise stimulus on the epigenetic level., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Purpose: This study was designed to evaluate the associations between retinal vascular complexity features, including fractal dimension (FD) and blood vessel tortuosity (BVT), and the severity of diabetic retinopathy (DR) by using optical coherence tomographic angiography (OCTA). Methods: In this prospective cross-sectional study, 1,282 ocular-treatment-naive patients with type 2 diabetes mellitus (DM) (1,059 without DR and 223 with DR) registered in the community of Guangzhou, China, were enrolled. OCTA was used to measure FD and BVT in the superficial capillary plexus (SCP) and the deep capillary plexus (DCP). Univariate and multivariate linear regression analyses were performed to analyze the correlation of FD and BVT in different layers with DR severity. Results: In this study, 1,282 patients with DM (1,282 eyes), with a mean age of 64.2 ± 7.8 years, were included. FD in the DCP decreased and BVT in the DCP increased in patients with DR compared with those in patients without DR, even after adjusting for confounding factors (p < 0.05). Trend analysis showed a significant decrease in the FD values as the DR progressed, whereas the BVT progressively increased with worsening DR severity (p < 0.01). The FD in DCP had a statistically significant positive correlation with FD in SCP and a negative correlation with BVT in SCP and BVT in DCP in all of the participants, including the non-DR group, moderate DR group, and severe DR group (p < 0.01). Conclusions: FD and BVT determined using OCTA might be useful parameters for objectively distinguishing DR from non-DR and indicating DR progression. [ABSTRACT FROM AUTHOR]

Background: Diabetic retinopathy (DR) is one of diabetes mellitus complication and occurred in retinal microvascular. This study was aimed to investigate the efficacy of Sambiloto, Andrographis paniculate (A. paniculata) extract on glycemic profile, antioxidant and inflammatory cytokine parameters in diabetic rats, and phytochemical analysis of A. paniculata. Methods: A. paniculata extract (APE) was carried out by maceration with ethanol. Diabetes mellitus in Wistar male rats was induced with streptozotocin. Retinal vessel diameters were estimated using a method by Vucetic. Inflammatory cytokine and antioxidant parameters were evaluated in retinal tissue. The alkaloid and flavonoid contents in extract were analyzed using thin layer chromatography method. Results: Funduscopic examination presented some changes in the diameter of the blood vessels. The vessel diameter in the diabetic retinopathy group with APE in concentration of 100 and 200 mg/kg BW groups was significantly lower than in the DR group (p<0.05). The administration of APE in dosages of 100 and 200 mg/kg BW showed reduced glutathione, SOD, and catalase levels compared to the DR group (p<0.05). Conclusions: A. paniculata extract doses of 100 and 200 mg/kg BW improved diabetic retinopathy in rats through hypoglycemic effects, antioxidant effects, and anti-inflammatory mechanisms. [ABSTRACT FROM AUTHOR]

The purpose of the study was to investigate the long-term effects of uncomplicated phacoemulsification on macular perfusion using optical coherence tomography angiography (OCTA) in healthy aging subjects. OCTA was performed before phacoemulsification and 1 week, 1 month, 3 months, and 6 months after. Superficial vascular complex (formed of nerve fiber layer vascular plexus and superficial vascular plexus), deep vascular complex (formed of intermediate capillary plexus and deep capillary plexus), as well as choriocapillaris (CC) and large choroidal blood vessels were recorded. Significant changes of vascular parameters in 95 eyes of 95 patients reached plateau 1 week after surgery and remained stable up to 6 months, occurring in all retinal layers but not in choroid and CC. Statistically significant increases in retinal vessels area, vessels percentage area, total number of junctions, junctions density, and total and average vessels length were found, followed by the total number of end points and mean lacunarity decline, proving an increase in blood supply. The study confirmed that uncomplicated phacoemulsification leads to a long-term increase in macular retinal perfusion. The results might ease the decision regarding timing for cataract surgery as long-term perfusion benefits can be achieved. Furthermore, study results provide a normative database of retinal and choroidal vasculature in healthy aging patients. [ABSTRACT FROM AUTHOR]

The morphology of retinal vessels is closely associated with many kinds of ophthalmic diseases. Although huge progress in retinal vessel segmentation has been achieved with the advancement of deep learning, some challenging issues remain. For example, vessels can be disturbed or covered by other components presented in the retina (such as optic disc or lesions). Moreover, some thin vessels are also easily missed by current methods. In addition, existing fundus image datasets are generally tiny, due to the difficulty of vessel labeling. In this work, a new network called SkelCon is proposed to deal with these problems by introducing skeletal prior and contrastive loss. A skeleton fitting module is developed to preserve the morphology of the vessels and improve the completeness and continuity of thin vessels. A contrastive loss is employed to enhance the discrimination between vessels and background. In addition, a new data augmentation method is proposed to enrich the training samples and improve the robustness of the proposed model. Extensive validations were performed on several popular datasets (DRIVE, STARE, CHASE, and HRF), recently developed datasets (UoA-DR, IOSTAR, and RC-SLO), and some challenging clinical images (from RFMiD and JSIEC39 datasets). In addition, some specially designed metrics for vessel segmentation, including connectivity, overlapping area, consistency of vessel length, revised sensitivity, specificity, and accuracy were used for quantitative evaluation. The experimental results show that, the proposed model achieves state-of-the-art performance and significantly outperforms compared methods when extracting thin vessels in the regions of lesions or optic disc. Source code is available at https://www.github.com/tyb311/SkelCon. [ABSTRACT FROM AUTHOR]

Vessel segmentation is critical for disease diagnosis and surgical planning. Recently, the vessel segmentation method based on deep learning has achieved outstanding performance. However, vessel segmentation remains challenging due to thin vessels with low contrast that easily lose spatial information in the traditional U-shaped segmentation network. To alleviate this problem, we propose a novel and straightforward full-resolution network (FR-UNet) that expands horizontally and vertically through a multiresolution convolution interactive mechanism while retaining full image resolution. In FR-UNet, the feature aggregation module integrates multiscale feature maps from adjacent stages to supplement high-level contextual information. The modified residual blocks continuously learn multiresolution representations to obtain a pixel-level accuracy prediction map. Moreover, we propose the dual-threshold iterative algorithm (DTI) to extract weak vessel pixels for improving vessel connectivity. The proposed method was evaluated on retinal vessel datasets (DRIVE, CHASE_DB1, and STARE) and coronary angiography datasets (DCA1 and CHUAC). The results demonstrate that FR-UNet outperforms state-of-the-art methods by achieving the highest Sen, AUC, F1, and IOU on most of the above-mentioned datasets with fewer parameters, and that DTI enhances vessel connectivity while greatly improving sensitivity. The code is available at: https://github.com/lseventeen/FR-UNet. [ABSTRACT FROM AUTHOR]