Retinal Flow Research Articles

VascuFit: Aerobic exercise improves endothelial function independent of cardiovascular risk: A randomized-controlled trial.

Background and aimsEndothelial 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). MethodsSedentary adults with elevated CV risk between 40-60 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. ResultsbaFMD 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. ConclusionsThe 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.

Quantification of capillary blood flow speeds in diabetic retinopathy using variable interscan time analysis (VISTA) OCTA.

To investigate retinal capillary plexus capillary flow speed and vessel density in diabetic retinopathy (DR) and normal subjects using variable interscan time analysis (VISTA) optical coherence tomography angiography (OCTA). High speed swept source OCTA imaging using multiple interscan times was performed over a 5 mm x 5 mm field-of-view with 600 kHz A-scan rate. Second-generation VISTA OCTA was used to measure a surrogate marker for capillary blood flow speed, VISTA flow speed (VFS), in the superficial and intermediate capillary plexuses, (SCP + ICP)VFS, and deep capillary plexus, DCPVFS. Vessel density was measured using OCTA. Fifty-seven eyes with different DR severity and 37 normal eyes were analyzed. VISTA OCTA provided diverse blood flow speed information, including pseudo-color OCTA and mean flow speed in different regions. Both DCPVFS and DCPVFS/(SCP + ICP)VFS were higher in DR compared to normal eyes. Elevated DCPVFS correlated with decreased DCP vessel density in non-proliferative DR. VISTA OCTA can measure a quantitative biomarker for blood flow speed alterations in DR and normal eyes as well as the association with vessel density in different capillary plexuses. VISTA OCTA is promising for studies of pathogenesis and early flow alterations which may precede non-perfusion.

Retinal thickness and macular microvascular changes seen on optical coherence tomography angiography (OCTA) in patients with sickle cell retinopathy in a tertiary care eye hospital

PurposeTo report retinal thickness values and macular vascular flow characteristics identified by optical coherence tomography angiography (OCT-A) in patients with various sickle cell genotypes in a population from sub-Saharan Africa. DesignRetrospective, observational study. MethodsThis is a single-institution case series of adult patients with various sickle cell genotypes who presented to the Eye Foundation Hospital Lagos between January 2022 and December 2023. Case files of patients were reviewed, and macular OCT and OCT-A images analyzed quantitatively for macular thickness, areas of flow loss, size of foveal avascular area, parafoveal flow, as well as vascular density in both the superficial and deep vascular plexi. The findings were compared by sickle cell genotype and comparisons made with age matched normal patients. ResultsA total of 38 eyes of 19 patients’ records were reviewed, and 35 eyes met the inclusion criteria; 16 eyes of 9 age and gender matched controls were included. The mean central foveal thickness (CFT) was 242.4 μm ± 33.3 μm among patients’ eyes, while a mean CFT of 236.1 μm ± 10.1 μm was measured among controls (p = 0.312). A smaller mean FAZ area of 0.270 mm2 ± 0.116 mm2 was seen among the control eyes compared to a mean of 0.314 mm2 ± 0.206 mm2 among patients’ eyes (p = 0.439). The mean flow area was larger among control eyes with 0.849 mm2 ± 0.647 mm2 compared to a mean flow of 0.822 mm2 ± 0.471 mm2 among patients’ eyes (0.868). The mean superficial foveal vessel density was greater among control eyes (19.30 ± 4.58) compared to patient eyes (18.77 ± 7.78) (p = 0.765). The mean deep foveal vessel density was greater among controls (35.30 ± 8.36) than among patients (34.06 ± 9.30) (p = 0.650). The difference between eyes of SC (53.37 ± 5.13) patients and SS (47.94 ± 8.44) patients in the deep temporal perifoveal VD was statistically significant (p = 0.035). ConclusionThe retina in eyes with sickle retinopathy and that of controls tends to be thickest in the nasal quadrant, then the superior, then inferior, and then thinnest in the temporal quadrant. Macular vessel density in both the superficial and deep capillary plexi was thicker among controls compared to eyes with sickle cell retinopathy. Among patients’ eyes, the deep capillary vessel density in the temporal perifoveal quadrant was greater among SC patients compared to SS (p = 0.035).

ECG–gated retinal vessel calibre as a novel measure of aberrant pulsatile retinal flow in diabetes mellitus: a cross-sectional study

ECG–gated retinal vessel calibre as a novel measure of aberrant pulsatile retinal flow in diabetes mellitus: a cross-sectional study

Lycium barbarum glycopeptide promotes neuroprotection in ET-1 mediated retinal ganglion cell degeneration

BackgroundVascular dysregulation is one of the major risk factors of glaucoma, and endothelin-1 (ET-1) may have a role in the pathogenesis of vascular-related glaucoma. Fruit extract from Lycium Barbarum (LB) exhibits anti-ageing and multitarget mechanisms in protecting retinal ganglion cells (RGC) in various animal models. To investigate the therapeutic efficacy of LB glycoproteins (LbGP) in ET-1 induced RGC degeneration, LbGP was applied under pre- and posttreatment conditions to an ET-1 mouse model. Retina structural and functional outcomes were characterised using clinical-based techniques.MethodsAdult C57BL/6 mice were randomly allocated into four experimental groups, namely vehicle control (n = 9), LbGP-Pretreatment (n = 8), LbGP-Posttreatment (day 1) (n = 8) and LbGP-Posttreatment (day 5) (n = 7). Oral administration of LbGP 1 mg/Kg or PBS for vehicle control was given once daily. Pre- and posttreatment (day 1 or 5) were commenced at 1 week before and 1 or 5 days after intravitreal injections, respectively, and were continued until postinjection day 28. Effects of treatment on retinal structure and functions were evaluated using optical coherence tomography (OCT), doppler OCT and electroretinogram measurements at baseline, post-injection days 10 and 28. RGC survival was evaluated by using RBPMS immunostaining on retinal wholemounts.ResultsET-1 injection in vehicle control induced transient reductions in arterial flow and retinal functions, leading to significant RNFL thinning and RGC loss at day 28. Although ET-1 induced a transient loss in blood flow or retinal functions in all LbGP groups, LbGP treatments facilitated better restoration of retinal flow and retinal functions as compared with the vehicle control. Also, all three LbGP treatment groups (i.e. pre- and posttreatments from days 1 or 5) significantly preserved thRNFL thickness and RGC densities. No significant difference in protective effects was observed among the three LbGP treatment groups.ConclusionLbGP demonstrated neuroprotective effects in a mouse model of ET-1 induced RGC degeneration, with treatment applied either as a pretreatment, immediate or delayed posttreatment. LbGP treatment promoted a better restoration of retinal blood flow, and protected the RNFL, RGC density and retinal functions. This study showed the translational potential of LB as complementary treatment for glaucoma management.

Diagnostic Capability of OCTA-Derived Macular Biomarkers for Early to Moderate Primary Open Angle Glaucoma.

Background/Objectives: To investigate macular vascular biomarkers for the detection of primary open-angle glaucoma (POAG). Methods: A total of 56 POAG patients and 94 non-glaucomatous controls underwent optical coherence tomography angiography (OCTA) assessment of macular vessel density (VD) in the superficial (SCP), and deep (DCP) capillary plexus, foveal avascular zone (FAZ) area, perimeter, VD, choriocapillaris and outer retina flow area. POAG patients were classified for severity based on the Glaucoma Staging System 2 of Brusini. ANCOVA comparisons adjusted for age, sex, race, hypertension, diabetes, and areas under the receiver operating characteristic curves (AUCs) for POAG/control differentiation were compared using the DeLong method. Results: Global, hemispheric, and quadrant SCP VD was significantly lower in POAG patients in the whole image, parafovea, and perifovea (p < 0.001). No significant differences were found between POAG and controls for DCP VD, FAZ parameters, and the retinal and choriocapillaris flow area (p > 0.05). SCP VD in the whole image and perifovea were significantly lower in POAG patients in stage 2 than stage 0 (p < 0.001). The AUCs of SCP VD in the whole image (0.86) and perifovea (0.84) were significantly higher than the AUCs of all DCP VD (p < 0.05), FAZ parameters (p < 0.001), and retinal (p < 0.001) and choriocapillaris flow areas (p < 0.05). Whole image SCP VD was similar to the AUC of the global retinal nerve fiber layer (RNFL) (AUC = 0.89, p = 0.53) and ganglion cell complex (GCC) thickness (AUC = 0.83, p = 0.42). Conclusions: SCP VD is lower with increasing functional damage in POAG patients. The AUC for SCP VD was similar to RNFL and GCC using clinical diagnosis as the reference standard.

Evaluation of ophthalmic vascular and neuroretinal alterations in fibromyalgia syndrome: a cross-sectional comparative study

IntroductionFibromyalgia syndrome (FMS) is a prevalent rheumatic disorder, and its pathogenesis includes genetic, neuroendocrine, and autonomic abnormalities, which may impact ocular structures. The aim was to conduct a comparative analysis of the ophthalmic vasculature and the retinal nerve fiber layer (RNFL) thickness between FMS and control groups using optical coherence tomography (OCT) and OCT angiography (OCTA).MethodsThis cross-sectional comparative study included 43 FMS patients and 40 healthy controls recruited from a tertiary education and research hospital between January 2024 and May 2024. All patients satisfied the 2016 American College of Rheumatology criteria for FMS and consented. OCT and OCTA were used to assess the RNFL thickness and the retinal microvasculature structure. The Fibromyalgia Impact Questionnaire (FIQ) was performed to evaluate disease severity.ResultsThe study found significantly higher total retinal parafoveal thickness and foveal density in FMS patients (p = 0.017 and p = 0.044, respectively). Nevertheless, there were no significant differences among the groups concerning total retinal foveal thickness, foveal avascular zone characteristics, superficial and deep capillary plexus densities, choriocapillaris flow area, and outer retinal flow area values (p > 0.05). The RNFL thickness in all quadrants did not reveal significant differences between the groups (p > 0.05). Furthermore, there was no significant correlation between FIQ scores and OCTA parameters or RNFL thickness values (p > 0.05).ConclusionThe study revealed slight differences in retinal parafoveal thickness and foveal density in FMS patients, but no substantial vascular or neurodegenerative alterations were observed compared to healthy controls. These data indicate that FMS may not substantially affect ocular structures, contrary to earlier hypotheses.

Measurement of retinal blood flow precision in the human eye with multimodal adaptive optics imaging.

Impaired retinal blood flow (RBF) autoregulation plays a key role in the development and progression of several ocular diseases, including glaucoma and diabetic retinopathy. Clinically, reproducible RBF quantitation could significantly improve early diagnosis and disease management. Several non-invasive techniques have been developed but are limited for retinal microvasculature flow measurements due to their low signal-to-noise ratio and poor lateral resolution. In this study, we demonstrate reproducible vessel caliber and retinal blood flow velocity measurements in healthy human volunteers using a high-resolution (spatial and temporal) multimodal adaptive optics system with scanning laser ophthalmoscopy and optical coherence tomography.

Retinal vessel density and choroidal flow changes in oligoarticular juvenile idiopathic arthritis with and without uveitis.

This cross-sectional optical coherence tomography angiography (OCTA) study aimed to assess the macular and optic nerve head (ONH) vascular density, foveal avascular zone, and outer retina and choriocapillaris flow in oligoarticular juvenile idiopathic arthritis (oJIA). Prospective. Twenty-two eyes of 22 oJIA patients with uveitis (oJIA-U), 20 eyes of 20 oJIA patients without uveitis (isolated oJIA), and 26 healthy volunteers of similar ages and sexes were investigated. The superficial capillary plexus (SCP) and deep capillary plexus (DCP), ONH, foveal avascular zone (FAZ) parameters, the flow area of the outer retina, and choriocapillaris were evaluated. Compared with the control group, both the oJIA-U group and isolated oJIA group showed significantly decreased vessel density of parafovea (p = 0.031 and p = 0.047, respectively) in DCP. Choriocapillaris flow area at 1mm radius was significantly lower in the oJIA-U group compared to the control group (p = 0.001). Choriocapillaris flow area at 2- and 3-mm radius were significantly lower in the oJIA-U group compared to the control group (p < 0.001, for both) and isolated oJIA-U group compared to the control group (p = 0.008 and p = 0.001, respectively). The VD and thickness parameters of SCP and ONH, FAZ, and outer retina flow area were similar between the groups. oJIA patients with and without uveitis revealed a decreased vessel density in the deep parafoveal region and choriocapillaris flow. Our findings suggest that retinal choroidal microvascular changes could be evident in oJIA-U patients without posterior segment involvement as well as oJIA patients without uveitis.

Transorbital ultrasound in the diagnosis of giant cell arteritis.

The objective of this study was to prospectively evaluate the diagnostic efficacy of transorbital ultrasound (TOS) in patients newly diagnosed with giant cell arteritis (GCA), presenting with visual symptoms. Patients with newly diagnosed, untreated GCA were examined using TOS, assessing central retinal artery flow velocity [peak systolic velocity (PSV), end-diastolic velocity (EDV), resistance index (RI)], and optic nerve diameter (OND). Vascular ultrasound was conducted to evaluate the superficial temporal arteries, their branches, facial, axillary, carotid, and vertebral arteries. We enrolled 54 GCA patients, 27 with visual symptoms, and 27 healthy controls. Eyes of GCA patients with visual symptoms demonstrated significantly lower PSV and EDV (PSV: β = -1.91; P = 0.029; EDV: β = -0.57; P = 0.032) and significantly elevated OND (β = 0.79; P = 0.003) compared with controls. RI did not significantly differ from controls (β = -0.06, P = 0.129). Vascular ultrasound identified an average of 8.7 (SD ± 2.8) pathological vessels per GCA patient. A significant negative association was observed between the number of affected vessels and both PSV (P = 0.048) and EDV (P = 0.040). No association was found with RI (P = 0.249), while a positive significant association was noted with OND (P < 0.001). This study pioneers the application of TOS to assess structural eye changes in newly diagnosed, untreated GCA patients with visual symptoms. Our findings suggest reduced central retinal artery flow and increased optic nerve diameter as potential biomarkers for serious ocular involvement in GCA. The detected association between internal and external carotid artery involvement indicates a common pathophysiological mechanism underlying systemic and ocular manifestations of GCA.

WHY HAPPENS A PROGRESSIVE DECREASE OF BLOOD PRESSURE AFTER RENAL DENERVATION

Objective: Long-term follow-up data from the SYMPLICITY 3 trial (Bhatt et al, Lancet, 2022) and the Global Symplicty Register data (Mahfoud et al, JACC, 2020) show a further decrease in BP over time up to 3 years post procedure. Yet these observations lack a mechanistic explanation. A decrease in vascular resistance could possibly explain the observed phenomenon. Scanning Laser Doppler Flowmetry (SLDF) allows the non-invasive assessment of vascular resistance and capillary density by using the retinal vasculature as a mirror of the systemic circulation. Design and method: Retinal parameters were assessed using SLDF together with office and 24-hour ambulatory BP before and 6 as well as 12 months after renal denervation in 63 patients with treatment resistant hypertension (TRH) (NCT01687725). SLDF allows the assessment of retinal capillary flow (RCF), pulsed retinal capillary flow (systolic retinal capillary flow – diastolic retinal capillary flow) (pRCF), retinal vascular resistance, capillary area (CapA) and intercapillary distance (ICD). Results: Mean age of the study cohort was 60±11 years, mean BMI 30.6±4.9 kg/m2. Patients took 5.8 antihypertensive medications on average. There was a significant reduction of systolic and diastolic 24-hour ambulatory as well office BP 6 as well as 12 months after RDN (table 1). There was no significant reduction in the number of antihypertensive medications taken between baseline and 12 months after RDN (5.8vs.5.7 antihypertensive pills, p=0.159). Retinal vascular resistance was reduced 6 months after RDN (table 1), pRCF was reduced 6 as well as 12 months after RDN and capillary density improved 12 months after RDN. Conclusions: In high-risk patients with TRH endovascular RDN improved vascular resistance and reversed capillary rarefaction in the retinal circulation, a prognostic marker of further end-organ damage. The reduction of pRCF indicates a decrease of shear stress on the vascular wall by the pulsed blood flow. Increment of capillary density was observed not already 6 months, but only 12 months after RDN. We conclude that, improvement of capillary rarefaction happens slowly after RDN and requires long-term effective BP control and, that reduction in vascular resistance might explain the prolonged BP reduction after RDN.

Progress and challenges of in vivo flow cytometry and its applications in circulating cells of eyes.

Circulating inflammatory cells in eyes have emerged as early indicators of numerous major diseases, yet the monitoring of these cells remains an underdeveloped field. In vivo flow cytometry (IVFC), a noninvasive technique, offers the promise of real-time, dynamic quantification of circulating cells. However, IVFC has not seen extensive applications in the detection of circulating cells in eyes, possibly due to the eye's unique physiological structure and fundus imaging limitations. This study reviews the current research progress in retinal flow cytometry and other fundus examination techniques, such as adaptive optics, ultra-widefield retinal imaging, multispectral imaging, and optical coherence tomography, to propose novel ideas for circulating cell monitoring.

Choroidal Changes in Patients with Diabetic Retinopathy: A Retrospective Study.

This study aimed to investigate the characteristic choroidal changes in patients with diabetic retinopathy and identify factors affecting choroidal thickness (CTh), choroidal vascular index (CVI), and choriocapillaris flow. We retrospectively analyzed 79 eyes of 48 patients with diabetes between August 2021 and February 2022. We collected laboratory data, including HbA1c, serum creatinine, blood urea nitrogen, triglyceride, total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL) levels. Optical coherence tomography images of the foveal avascular zone, retinal vascular density, choroidal flow, retinal thickness, CTh, and CVI were analyzed. Possible determining factors affecting CTh, CVI, and choriocapillaris flow were analyzed using nonparametric multivariate analysis. LDL (p < 0.001) positively correlated with CTh, whereas CVI (p = 0.007) was negatively correlated with CTh in diabetic patients with diabetes. We also identified a negative correlation between choriocapillaris flow and deep parafoveal retinal vessel density in patients with low-grade diabetic retinopathy (DR), which diminished in those with more advanced DR. Our study provides further information on the changes in choroidal structure and blood flow in patients with diabetes.

High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmoscope.

High-speed, phase contrast retinal and blood flow imaging using an adaptive optics partially confocal multi-line ophthalmosocope (AO-pcMLO) is described. It allows for simultaneous confocal and phase contrast imaging with various directional multi-line illumination by using a single 2D camera and a digital micromirror device (DMD). Both vertical and horizontal line illumination directions were tested, for photoreceptor and vascular imaging. The phase contrast imaging provided improved visualization of retinal structures such as cone inner segments, vessel walls and red blood cells with images being acquired at frame rates up to 500 Hz. Blood flow velocities of small vessels (<40 µm in diameter) were measured using kymographs for capillaries and cross-correlation between subsequent images for arterioles or venules. Cardiac-related pulsatile patterns were observed with normal resting heart-beat rate, and instantaneous blood flow velocities from 0.7 to 20 mm/s were measured.

OCTA characteristics in non-arteritic central retinal artery occlusion and correlation with visual acuity.

To observe the retinal and choroidal circulations in patients with non-arteritic permanent central retinal artery occlusion (NA-CRAO) via optical coherence tomography angiography (OCTA) and analyze their correlation with visual acuity. Sixty-two eyes with clinically confirmed acute NA-CRAO were included in the study and divided into: A type (mild n=29), B type (moderate n=27) and C type (severe n=6) based on the degree of visual loss, retinal edema, and arterial blood flow delay in fundus fluorescence angiography (FFA). Contralateral healthy eyes were used as the control group. Best-corrected visual acuity (BCVA), slit lamp microscopy, indirect ophthalmoscopy, fundus color photography, OCTA, and FFA were performed. Spearman's correlation analysis was used to determine the correlations between retinal and choroidal vessels and visual acuity. There were no statistically significant differences in age, gender, and intraocular pressure among the three types and the control group (P>0.05). Vessel density in deep capillary plexus (VD-DCP) significantly decreased (P<0.05) in all three types of NA-CRAO patients compared to the control group. Vessel density in superficial vascular plexus (VD-SVP) significantly decreased (P<0.05) in type A patients and choriocapillaris flow area significantly decreased (P<0.05) in type B and type C patients compared to the control group; while outer retinal flow areas significantly increased in the type A (P<0.05) and decreased in type C patients (P<0.05). The retinal thickness significantly increased in type C group (P<0.05). The VD-SVP at fovea in the type A was significantly lower than both of type B and C. The VD-SVP at nasal parafovea in type A and B was significantly lower than type C (P<0.05). The logMAR BCVA of type A was significantly better than that of type B and C groups (P<0.05). Spearman's correlation analysis showed that the logMAR BCVA was positively correlated with VD-SVP at fovea (r=0.679, P=0.031) and nasal parafovea (r=0.826, P=0.013). OCTA is valuable for assessing retinal ischemia, and evaluating visual impairment. Deep retinal vasculature is commonly affected in all NA-CRAO types. VD-SVPs at fovea and nasal parafovea can serve as reliable markers of visual impairment in NA-CRAO.

Central and Peripheral Changes in Retinal Vein Occlusion and Fellow Eyes in Ultra-Widefield Optical Coherence Tomography Angiography.

To explore the central and peripheral retinal and choroidal changes in retinal vein occlusion (RVO) and fellow eyes using ultra-widefield swept-source optical coherence tomography angiography (UWF-SS-OCTA). Fifteen ischemic central RVO (CRVO), 15 branch RVO (BRVO), and 15 age-matched healthy controls were prospectively recruited. Retinal and choroidal parameters, including retinal vessel flow density (VFD) and vessel linear density (VLD), choroidal vascularity volume (CVV), choroidal vascularity index (CVI), and VFD in the large and medium choroidal vessels (LMCV-VFD), were measured in the central and peripheral regions of the 24 × 20-mm UWF-SS-OCTA images. Ischemic CRVO and BRVO eyes showed increased foveal avascular zone area, perimeter, and acircularity index (AI) compared to their fellow eyes and healthy control eyes, and RVO fellow eyes also had larger AI values than controls (P < 0.05). For ischemic CRVO and BRVO eyes versus control eyes, VFD, VLD, CVV, CVI, and LMCV-VFD decreased, but retinal thickness and volume in the superficial capillary plexus, deep capillary plexus, and whole retina increased (P < 0.05). Moreover, RVO fellow eyes also showed significantly decreased retinal VFD, LMCV-VFD, and CVI, as well as increased retinal thickness and volume, compared with control eyes (P < 0.05). Alterations were not consistent throughout the retina, as they involved only the peripheral or central regions in some cases. The affected and unaffected fellow eyes of RVO patients both demonstrated central and/or peripheral structural and vascular alterations in the retina and choroid. Because UWF-SS-OCTA enables visualization and evaluation of the vasculature outside the posterior pole, it presents a promising approach to more fully characterize vascular alterations in RVO.

The Preserflo MicroShunt Affects Microvascular Flow Density in Optical Coherence Tomography Angiography.

Intraocular pressure (IOP) lowering surgery has been shown to alter microvascular density in glaucoma patients. The aim of this study is to report changes in retinal flow density (FD) over the course of treatment with the Preserflo MicroShunt, using optical coherence tomography angiography (OCTA). 34 eyes from 34 patients who underwent Preserflo MicroShunt implantation were prospectively enrolled in this study. OCTA imaging was conducted at the superficial (SCP), deep (DCP) and radial peripapillary plexus (RPC) levels. The progression of FD and IOP was assessed at different time points from baseline to six months postoperatively for the entire patient population, as well as disease severity subgroups. The Preserflo MicroShunt achieved a significant reduction in IOP over the course of six months (median: 8 mmHg; p < 0.01). FD values of the SCP and DCP did not show significant fluctuations, even after adjusting for disease severity. FD of the RPC decreased significantly over the course of six months postoperatively from 42.31 at baseline to 39.59 at six months postoperatively (p < 0.01). The decrease in peripapillary FD was strongest in patients with advanced glaucoma (median: -3.58). These observations hint towards dysfunctional autoregulatory mechanisms in capillaries surrounding the optic nerve head in advanced glaucoma. In comparison, the microvascular structure of the macula appeared more resilient to changes in IOP.

Mouse model of radiation retinopathy reveals vascular and neuronal injury

PurposeTo characterize the neuronal and vascular pathology in vivo and in vitro in a mouse model of radiation retinopathy. MethodsC57Bl/6J mice underwent cranial irradiation with 12 Gy and in vivo imaging by optical coherence tomography and of relative blood flow velocity by laser speckle flowgraphy for up to 3–6 months after irradiation. Retinal architecture, vascular density and leakage and apoptosis were analyzed by histology and immunohistochemistry before irradiation or at 10, 30, 240, and 365 days after treatment. ResultsThe vascular density decreased in the plexiform layers starting at 30 days after irradiation. No impairment in retinal flow velocity was seen. Subtle perivascular leakage was present at 10 days, in particular in the outer plexiform layer. This corresponded to increased width of this layer. However, no significant change in the retinal thickness was detected by OCT-B scans. At 365 days after irradiation, the nuclear density was significantly reduced compared to baseline. Apoptosis was detected at 30 days and less prominent at 365 days. ConclusionsBy histology, vascular leakage at 10 days was followed by increased neuronal apoptosis and loss of neuronal and vascular density. However, in vivo imaging approaches that are commonly used in human patients did not detect pathology in mice.

Associations between retinal microvascular flow, geometry, and progression of diabetic retinopathy in type 2 diabetes: a 2-year longitudinal study.

To determine the association between retinal blood vessel flow and geometric parameters and the risk of diabetic retinopathy (DR) progression through a 2-year prospective cohort study. Patients with type 2 diabetes mellitus (T2DM) were recruited from a diabetic registry between November 2017 and March 2019. All participants underwent standardized examinations at the baseline and 2-year follow-up visit, and the presence and severity of DR were assessed based on standard seven-field color fundus photographs. They also underwent swept-source optical coherence tomography angiography (OCTA) imaging to obtain measurements of foveal avascular zone area, blood vessel density (VD), fractal dimension (FD), blood vessel tortuosity (BVT) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). A total of 233 eyes of 125 patients were included, and 40 eyes (17.17%) experienced DR progression within 2years. DR progression was significantly associated with lower baseline VD (odds ratio [OR] 2.323 per SD decrease; 95% confidence interval [CI] 1.456-3.708; P < 0.001), lower FD (OR, 2.484 per SD decrease; 95% CI 1.268-4.867; P = 0.008), and higher BVT (OR, 2.076 per SD increase; 95% CI 1.382-3.121; P < 0.001) of the DCP after adjusting for confounding factors. The addition of OCTA metrics improved the predictive ability of the original model for DR progression (area under the curve [AUC] from 0.725 to 0.805; P = 0.022). OCTA-derived VD, FD and BVT in the DCP were independent predictors of DR progression and showed additive value when added to established risk models predicting DR progression.

Optical coherence tomography angiography parameters in patients taking hydroxychloroquine therapy.

The aim of this study is to measure retinal vessel density and flow rate area by optical coherence tomography angiography (OCTA) in patients with autoimmune diseases taking hydroxychloroquine (HCQ). The cross-sectional study included 98 patients divided into three groups. Group I included patients with the diagnosis of an autoimmune disease, for whom the introduction of HCQ was planned. Group II implied low-risk patients for retinal toxicity (≤5 years of HCQ use), whereas Group III implied patients that were at high-risk (>5 years of drug use). All patients underwent a computerized visual field, central macular thickness by optical coherence tomography, and OCTA measurements. The vascular density was found to be statistically significantly decreased in the high-risk group compared to the control group in the superficial parafoveal zone (P = 0.030), whereas it was decreased compared to the low-risk and control groups in the deep layers whole (P = 0.006, P = 0.010, respectively) and perifoveal zones (P = 0.003, P = 0.010, respectively). The foveal avascular zone was significantly enlarged in the high-risk group compared to the control (P < 0.018). Retinal flow rates did not show statistically significant differences between the groups (P > 0.05). Patients treated with HCQ for more than 5 appear have a significant loss of vascular density in the parafoveal and perifoveal regions, and FAZ area is significantly increased compared to low-risk patients and controls. These findings indicate that OCTA may be beneficial for monitoring high-risk patients and may stratify their risk of further retinal damage.