Superficial Retinal Capillary Research Articles

Microvascular Changes of the Non-surgical Eye after General Anesthesia in Optical Coherence Tomography Angiography

Purpose: To investigate chorioretinal vascular changes in the non-surgical eyes of patients who underwent vitreoretinal surgery under general anesthesia using optical coherence tomography angiography (OCTA).Methods: Data from 40 patients who underwent retinal surgery were retrospectively analyzed. Ophthalmologic examinations (including OCTA) were performed in the morning before and after surgery. The presence of intraoperative hypotension (IOH; mean arterial pressure <70 mmHg) was determined based on medical records. The vessel density of superficial and deep retinal capillary plexus layers, choriocapillaris void features, and thickness of the choroid and retina were quantified after image processing. Associations between retinal OCTA parameters and anesthesia profiles were also assessed.Results: DCP vessel density was increased after general anesthesia (p < 0.05). Among the patients who experienced IOH, there was no statistical difference in chorioretinal vessel parameters before and after general anesthesia. Also, we did not observe a difference in chorioretinal vessel parameters after general anesthesia between healthy patients and patients with chronic disease, including hypertension and diabetes (p > 0.05). The duration of anesthesia and average size of the choriocapillaris void (p < 0.05, r = -0.32), and the intraoperative mean arterial pressure (MAP) fluctuation and DCP, showed statistically significant negative linear correlations (p < 0.05, r = -0.38). The choriocapillaris void size and intraoperative MAP fluctuation also displayed a significant negative correlation (p < 0.05, r = -0.37), while the average size signal void showed a weak positive linear correlation (p < 0.01, r = 0.41; and p < 0.01, r = 0.44, respectively).Conclusions: This is the first study to assess the effects of general anesthesia on chorioretinal vessels using OCTA. The Vessel density of the DCP was significantly increased in the non-surgical eye after total vitrectomy under general anesthesia. Furthermore, we found a correlation between MAP fluctuation and choriocapillaris void features. More studies are needed to confirm and expand on these observations.

The Value of Optical Coherence Tomography Angiography in Pituitary Adenomas.

This study aims to explore the value of retinal vessel density (VD) in diagnosing optic nerve injuries in patients with pituitary adenomas using optical coherence tomography angiography (OCTA). In this cross-sectional retrospective study, 100 patients with pituitary adenomas and 71 participants for normal controls, who visited the Beijing Tiantan Hospital from January 2019 to May 2021, were enrolled. The OCTA was used to measure retinal thickness and VD, and the correlation of these parameters with visual field (VF) factors was analyzed. Receiver operating characteristic curves were used to compare the value of the above parameters in diagnosing VF abnormalities in the patients with pituitary adenomas; the differences in retinal VD between 41 patients with pituitary adenomas who had normal retinal thicknesses and 41 patients in the normal control group with no statistical differences in gender and age were compared. The radial peripapillary capillary (RPC) density, superficial retinal capillary plexus (SRCP) density, retinal nerve fiber layer thickness, and ganglion cell layer complex thickness correlated with VF parameters (p < 0.05). The RPC density in the temporal quadrant had the highest capability in diagnosing VF abnormalities, with an area under the curve = 0.821, p < 0.001, with 72.3% sensitivity and 82.7% specificity. The mean RPC density and RPC density in the nasal and temporal quadrants in the 41 patients with pituitary adenomas who had normal retinal thicknesses were reduced compared with the normal control group (49.95% ± 1.86% vs. 51.30% ± 1.87%, p = 0.002; 49.09% ± 3.13% vs. 50.41% ± 3.90%, p = 0.034; 54.33% ± 3.14% vs. 55.89% ± 3.08%, p = 0.020) and other parameters had no statistical differences compared with the normal control group. The density of the RPC and SRCP may also be sensitive and specific indicators of VF damage in patients with pituitary adenomas. Measuring retinal VD in patients with pituitary adenomas may be a supplement to help identify VF impairments. In addition, abnormal retinal vascular density may indicate VF impairment in patients who are unable to cooperate with VF examinations.

WIDEFIELD SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY FINDINGS IN WAGNER SYNDROME.

To describe novel clinical and angiographic findings in Wagner syndrome. A retrospective case series of three related patients with Wagner syndrome. Patients underwent standard optical coherence tomography (OCT), B-scan ultrasonography, and fluorescein angiography in addition to wide field swept-source OCT angiography (WF SS-OCTA) (PLEX Elite 9000, Carl Zeiss Meditec Inc). Patients underwent genetic testing for a panel of hereditary vitreoretinopathies. Three related patients with Wagner syndrome were identified. All were found to have prominent vitreous strands, abnormal vitreoretinal adhesions, peripheral retinal holes, and varying degrees of myopia. A mid-peripheral tractional ridge was identified in all six eyes. All patients were positive for a known pathologic intron variant in the VCAN gene (4004-5T-A). Wide field swept-source OCT angiography (12 mm × 12 mm) was performed in two patients and demonstrated perivascular capillary loss in the superficial capillary plexus along the arcades bilaterally. One patient demonstrated associated retinal atrophy within the area of capillary loss. The capillary loss extended beyond the margin of retinal atrophy. The unusual finding of a mid-peripheral tractional ridge of the retina associated with myopia led to a genetic diagnosis of Wagner syndrome. Widefield swept-source OCT angiography demonstrated a novel feature of perivascular loss of the superficial retinal capillary plexus. This result suggests that vitreous traction may cause localized microvasculature dysfunction and subsequent retinal atrophy in Wagner syndrome. This is the first known evaluation of Wagner syndrome using OCT angiography.

Association of self-reported snoring with decreased retinal thickness and vessel density.

Purpose: Self-reported snoring has been reported to influence nerves and vessels. However, there are few direct evidences of snoring related to nerves and microvessels defects. Therefore, we evaluated the association of self-reported snoring with retinal structure and microcirculation. Methods: A total of 2,622 participants were recruited from the Jidong eye cohort study (JECS). Physical examinations, laboratory tests, and questionnaires were recorded. We also used optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) to assess the retinal structure and microvascular network. Snoring was defined as “never,” “occasionally,” and “frequently or more severe” according to self-reported frequency. Results: The prevalence of snoring were 84.6% (n = 983) and 45.0% (n = 657) in males and females, respectively. Compared with never snoring group, the retinal thickness increased in “occasionally” (p < 0.001) and “frequently or more severe” groups (p = 0.001), while no difference was found between snoring groups (p = 0.14). Superficial retinal capillary plexus (RCP) vessel density was lower in “frequently or more severe” group than in “never” (p < 0.001) and “occasionally” snoring groups (p < 0.001). After adjusting for confounders, “frequently or more severe” snoring was significantly associated with thinner total retinal thickness [β = −2.79 (95% CI: −5.27, −0.30)] and lower superficial RCP vessel density [β = −0.71 (95% CI: −1.19, −0.23)]. Conclusion: Our research showed self-reported snoring was associated with thinner retinal thickness and lower superficial RCP vessel density. The findings of our study emphasize the need for self-reported snoring assessments in determining retinal structure and microcirculation impairment.

Association between retinal vessel density and neuroimaging features and cognitive impairment in cerebral small vessel disease

AimsThis study aimed to investigate the associations among retinal vessel density (RVD), neuroimaging features and cognitive impairment in patients with sporadic cerebral small vessel disease (CSVD). MethodsThis was a prospective observational study. A total of forty-nine patients with CSVD were recruited. The CSVD imaging burden was calculated by using a scoring system with a total score of 4 that assigns one point each for severe white matter hyperintensities (WMH), lacune, microbleeds (MBs), and basal-ganglia perivascular space (BG-PVS). Patients with a burden score ≥ 2 were classified as having a moderate/severe burden, and those with a score ≤ 1 were classified as the having a none/mild burden. The RVD in the superficial retinal capillary plexus (SRCP) and deep retinal capillary plexus (DRCP) was evaluated by using optical coherence tomography angiography (OCTA). The associations among the RVD values, CSVD imaging features, and cognitive impairment were evaluated. ResultsPatients with a moderate/severe CSVD burden showed lower RVD values in the para-fovea and peri-fovea areas of the left DRCP than patients with none/mild burden (para-fovea, β coefficient= −0.185 [−0.351~−0.015], P = 0.003; peri-fovea, β coefficient= −0.113 [−0.208~−0.018], P = 0.021). The RVD values in the para-fovea and peri-fovea areas of the left DRCP were significantly associated with the CSVD burden score after adjusting for age and vascular risk factors (P = 0.030 and P = 0.021, respectively) and with severe WMH (para-fovea, R = −0.398, P = 0.005; peri-fovea, R= −0.443, P = 0.001) and BG-PVS (para-fovea, R = −0.445, P = 0.001; peri-fovea, R= −0.396, P = 0.005). Neither para-fovea nor peri-fovea RVD values had a marked association with cognition. ConclusionThe RVD in the left DRCP may reflect the presence of cerebral small vessel lesions and might be a useful tool for predicting the neuroimaging-based burden of CSVD.

Parapapillary Choroidal Microvasculature Predicts Diabetic Retinopathy Progression and Diabetic Macular Edema Development: A Three-Year Prospective Study

To determine the predictive value of the microcirculation of the optic nerve head by swept-source optical coherence tomography angiography for identifying individuals with high risk of diabetic retinopathy (DR) progression and diabetic macular edema (DME) development. Prospective observational cohort study. A total of 946 patients (1879 eyes) with type 2 diabetes mellitus were recruited who had no DR or mild nonproliferative DR at baseline, and no DME. All subjects underwent 3×3 mm swept-source optical coherence tomography angiography centered on the optic nerve head to generate angiograms in 4 layers: radial peripapillary plexus, superficial retinal capillary plexus (SCP), deep retinal capillary plexus, and choriocapillaris (CC). The CC flow deficit percentage (CC FD%), vessel density (VD), and perfusion density (PD) were quantified. During the 3 consecutive years of follow-up, 312 eyes (16.60%) experienced DR progression and 115 eyes (6.12%) developed DME. The DR progression was related to a lower VD of the SCP (relative risk per standard deviation decrease, 95% confidence interval): 1.30, 1.14-1.48; P < .001), a lower PD of the SCP (1.41, 1.24-1.60; P < .001), a lower VD of the radial peripapillary plexus (1.23, 1.08-1.40; P=.002), and an elevated CC FD% (1.62, 1.40-1.88; P < .001). The DME occurrence was associated with a lower VD of SCP (1.35, 1.09-1.66; P=.005), a lower PD of SCP (1.29, 1.05-1.59; P=.016), and a higher CC FD% (1.29, 1.03-1.61; P < .001). The CC FD% significantly improved the predictive power, with the increase of the C-statistic for DR progression and DME occurrence by 3.83% (P=.002) and 5.24% (P < .001), respectively. This study provides the first longitudinal evidence suggesting that peripapillary CC FD% can improve the prediction of DR progression and DME development beyond traditional risk factors.

Valsalva Retinopathy: A Case Report

Valsalva retinopathy is characterised by pre-retinal haemorrhage which presents with unilateral, sudden, painless diminution of vision. Pre-retinal haemorrhage caused by sudden rise in venous pressure was first termed as Valsalva haemorrhage by Duane TD in 1972. It is caused by rupture of superficial retinal capillaries due to increased intra-ocular venous pressure following increase in intra-thoracic or intraabdominal pressure. It resolves in few weeks or month and vision returns to normal depending on the location of the bleed on the retina. Observation, Nd:YAG (neodymium-doped yttrium aluminium garnet) laser and Argon laser hyaloidotomy, vitrectomy are effective treatment options for eyes with Valsalva retinopathy. Here we present a case of a 32 year old female with Valsalva retinopathy with subhyaloid haemorrhageafter an episode of vomiting who was treated with Nd:YAG laser hyaloidotomy with a good visual outcome.The novelty of this case report lies in the fact that although conservative management is practiced more often with similar prognosis, early intervention by Nd:YAG laser hyaloidotomycan benefit the patient with marked improvement and rapid recovery. Key words: Valsalva retinopathy, subhyaloid haemorrhage, Nd:YAG laser hyaloidotomy.

Evaluation of subclinical ocular involvement in patients with deficiency of adenosine deaminase 2 (DADA2).

To evaluate changes in the peripapillary, macular, and choroidal microvasculature in the eyes of patients with deficiency of adenosine deaminase 2 (DADA2) and no clinical signs of ocular involvement. The study included 12 eyes of 12 patients with DADA2 and 24 eyes of 24 healthy subjects. The foveal avascular zone (FAZ), macular vessel densities (VDs) in the superficial and deep retinal capillary plexuses, peripapillary VDs, and choroidal thickness were evaluated by optical coherence tomography angiography (OCTA). Measurements were compared between DADA2 patients and healthy controls. The median age was 17 (8-25) years in DADA2 patients and 17.5 (7-23) years in control group at the OCTA visit (p = 0.934). FAZ area did not differ between the groups (p = 0.224). In the superficial capillary plexus, whole-image, foveal, and parafoveal VD values were slightly lower in DADA2 patients than in controls (p = 0.054, p = 0.052, p = 0.117). In the deep capillary plexus, whole-image and parafoveal VD values were significantly lower in DADA2 patients than controls (p = 0.010, p = 0.001). VD in the radial peripapillary capillary plexus was also lower in DADA2 patients, with significantly lower peripapillary VD (p = 0.002). Subfoveal choroidal thickness was significantly higher in patients with DADA2 (p < 0.001). This OCTA study demonstrates that both retinal and choroidal involvement may occur in DADA2 patients before the emergence of evident clinical findings.

Fundus Changes Evaluated by OCTA in Patients With Cerebral Small Vessel Disease and Their Correlations: A Cross-Sectional Study.

ObjectiveTo detect fundus changes in patients with cerebral small vessel disease (CSVD) using optical coherence tomography angiography (OCTA) and to investigate the correlations between CSVD and fundus changes.MethodsFrom January 2019 to January 2020, patients diagnosed with CSVD by magnetic resonance imaging (MRI) were enrolled in our study and received fundus examinations using OCTA. CSVD was defined as white matter hyperintensities, enlarged perivascular spaces, lacunes, or microbleeds on MRI. OCTA parameters included foveal avascular zone areas, retinal nerve fiber layer thickness, and capillary densities of the superficial retinal capillary plexuses, deep retinal capillary plexuses, and the radial peripapillary capillary network of the disc. Univariate and multivariate logistic regression analyses were performed to explore the correlation between CSVD and fundus changes.ResultsA total of 115 patients (40% male) were enrolled and analyzed, and the mean age was 65.11 ± 11.23 years. After multivariate logistic regression analysis, the radial peripapillary capillary network density was negatively correlated with severity of deep white matter lesions (OR: 0.909; 95% CI: 0.828–0.998; p = 0.046) and perivascular spaces (OR: 0.881; 95% CI: 0.779–0.995; p = 0.041). Parafoveal vessel densities of the superficial retinal capillary plexuses were independently correlated with lacunes (OR: 0.889; 95% CI: 0.817–0.967; p = 0.006).ConclusionOCTA parameters were correlated with CSVD, indicating that OCTA is a potential method for CSVD screening.

Reduced Radial Peripapillary Capillary in Pathological Myopia Is Correlated With Visual Acuity.

PurposeTo quantify the radial peripapillary capillary (RPC) density and the peripapillary retinal nerve fiber layer (pRNFL) thickness in pathological myopia and examine associations among these factors and best-corrected visual acuity (BCVA).MethodsThe cohort was composed of 41 eyes as control and 79 eyes with high myopia (59 simple high myopia, 20 pathological myopia). Optical coherence tomography angiography was done to obtain RPC density and pRNFL thickness, superficial retinal capillary plexus (SRCP), and deep retinal capillary plexus (DRCP) density. The axial length (AL) was measured. Correlations among BCVA, RPC density, pRNFL thickness, AL, and other parameters were determined.ResultsFor pathological myopia, the densities of RPC, SRCP, and DRCP were significantly less than those of the control and simple high myopia groups (p ≤ 0.005). There was no statistical difference in pRNFL thickness between pathological myopia and simple high myopia (p = 0.063), whereas there was significant difference in global pRNFL thickness between pathological myopia and control (p = 0.008). The global RPC density showed the greatest area under the curve (AUC = 0.962, sensitivity = 94.74%, specificity = 90.00%, cutoff value = 47.8%) for pathological myopia, whereas the AUC of pRNFL thickness, SRCP, and DRCP were only 0.675, 0.824, and 0.865, respectively. The univariate and multiple linear regression models showed that RPC density, SRCP density, and AL were correlated with BCVA (All p < 0.05). In the final BCVA model with multiple generalized estimating equation analysis, AL, RPC density and interaction between RPC and AL were shown (all p < 0.03). For an eye with AL ≥ 27.94 mm, global RPC density was predicted to be less than 48.77% with a high risk of visual impairment.ConclusionPeripapillary alterations, both the decreasing RPC density and pRNFL thickness, occurred in pathological myopia compared with the control. The RPC density was associated with BCVA, and this relationship was affected by AL.

Parafoveal and peripapillary vessel density in pediatric and juvenile craniopharyngioma patients

We assessed the retinal microvascular alterations detected by optical coherence tomography angiography (OCT-A) in pediatric and juvenile craniopharyngioma (CP) patients with chiasmal compression. We included 15 eyes of 15 pediatric or juvenile CP patients and 18 eyes of 18 healthy subjects. The evaluation of vessel density from the superficial retinal capillary plexus (SRCP), the deep retinal capillary plexus, and the radial peripapillary capillary (RPC) segments was obtained by OCT-A. The association between vessel density measures and functional and structural measurements was also analyzed. There were significant reductions in the nasal sector of the SRCP (p < 0.0001) and all sectors of the RPC segment vessel density (nasal, temporal, and superior; p < 0.0001, inferior; p = 0.0015) in CP patients postoperatively compared to the healthy subjects. The peripapillary retinal nerve fiber layer (r = 0.6602, p = 0.0074) and ganglion cell-inner plexiform layer thicknesses (r = 0.7532, p = 0.0030) were associated with RPC segment vessel density. Visual acuity (r = − 0.5517, p = 0.0330) and temporal visual field sensitivity loss (r = 0.5394, p = 0.0465) showed an association with SRCP vessel density. In pediatric and juvenile patients with CP, parafoveal and peripapillary vascular changes following chiasmal compression were observed. The changes in vascular structures were closely related to structural and functional outcomes.

Distribution characteristics of retinal nerve fiber layer thickness in macular area and its relationship with vessel density in highly myopic eyes

AIM: To investigate the distribution characteristics of retinal nerve fiber layer thickness and vessel density in macular area of eyes with high myopia, using optical coherence tomography angiography (OCTA). METHODS: Forty eyes in 20 patients diagnosed with high myopia, age 29.90±7.92 years old, with a spherical equivalent of -8.95±2.01 D, were recruited. The retinal nerve fiber layer (RNFL) thickness and the vessel density of the superficial retinal capillary plexus, deep retinal capillary plexus, and choroidal capillary were measured by OCTA. Macular regions within a 6-mm diameter circle were divided into 9 subfields: the central subfield, and the pericentral and peripheral regions of superior, inferior, nasal, and temporal quadrants. The retinal nerve fiber layer thicknesses of different subfields were compared, and their relationships with spherical equivalent, axial length, and vessel density were analyzed. RESULTS: In the pericentral region, the retinal nerve fiber layer thickness of the superior quadrant was the lowest, whereas thickness was highest in the inferior quadrant (all P&lt;0.05). In the peripheral region, the retinal nerve fiber layer thickness of the temporal quadrant was the lowest (all P&lt;0.05). A negative correlation was found between the retinal nerve fiber layer thickness and spherical equivalent (r=-0.356, P=0.024) in the peripheral superior subfield. The vessel density of superficial retinal capillary plexus was positively correlated with retinal nerve fiber layer thickness in the nasal and inferior quadrants of the pericentral region and in the superior, nasal, and inferior quadrants of the peripheral region (r=0.314, 0.408, 0.467, 0.655, and 0.737 respectively; and all P&lt;0.05), whereas the vessel density of choroidal capillary was negatively correlated with retinal nerve fiber layer thickness in the peripheral superior subfield (r= -0.356, P=0.024). CONCLUSION: The RNFL of macular areas is not uniformly distributed in high myopia (HM). As the spherical equivalent (SE) increases, the RNFL thickness decreases in certain areas, which correlates with the vessel density(VD) of superficial retinal capillary plexus (SCP) and choroidal capillary (CC) layers.

Microvascular Changes After Conbercept Intravitreal Injection of PDR With or Without Center-Involved Diabetic Macular Edema Analyzed by OCTA.

PurposeTo investigate the intravitreal injection of conbercept as a treatment strategy for proliferative diabetic retinopathy (PDR) with or without center-involved diabetic macular edema (CI-DME) and evaluate its effect on the microvascular changes in the eyes.MethodsIn this prospective study, 43 patients including 29 cases (56 eyes) in CI-DME with PDR patients, and 14 cases (26 eyes) in the non-center involving diabetic macular edema (NCI-DME) with PDR patients were involved in this study. The best corrected visual acuity (BCVA), central retinal thickness (CRT), foveolar avascular zone (FAZ), and macular capillary vessel density (VD) of the superficial retinal capillary plexus (SCP) and deep retinal capillary plexus (DCP) were assessed before and after conbercept treatments for 1, 3, or 6 months.ResultsThe BCVA was significantly increased after conbercept treatment in the eyes of CI-DME patients. After 6 months of treatment with the conbercept, microvascular density of the inferior area in SCP and the central fovea area in DCP increased significantly, regardless of the central fovea involvement. The effect of the conbercept treatment on the VD of NCI-DME was higher than that of CI-DME. Then, after 6 months of treatment, the CRT of patients with CI-DME and NCI-DME were decreased significantly.ConclusionsIn this study, an intravitreal injection of conbercept significantly improved vision, alleviated macular edema in patients with DME. Conbercept treatment also altered the microvascular density in the retina.

Evaluation of macular vessel density changes after strabismus surgery using optical coherence tomography angiography

To compare retinal vessel density before and after strabismus surgery using swept-source optical coherence tomography angiography (SS-OCTA). In this longitudinal, single-arm pilot study, vascular density in the deep capillary plexus (DCP), superficial retinal capillary plexus (SCP) and choriocapillaris layer (CCL) in consecutive subjects undergoing strabismus surgery was assessed using SS-OCTA preoperatively (T0), on the first day postoperatively (POD1), and 30 days postoperatively (POD30). A total of 92 eyes of 56 patients (54% males) were included. Mean patient age was 41.1 ± 22.7. OCT vascular density of the DCP was 50.20 ± 5.57 at T0, 52.74 ± 4.77 at POD1, and 50.92 ± 4.58 at POD30. The differences were statistically significant for T0 versus POD1 (P < 0.05). Vascular density of the CCL was 50.72 ± 4.80 at T0, 53.59 ± 3.65 at POD1, and 51.39 ± 4.64 at POD30. The differences were statistically significant for T0 versus POD1 (P < 0.05). No significant differences were found in SCP (P > 0.05). Transitory hemodynamic changes can occur in the DCP and in the CCL following muscle recession procedures.

Relationship of Quantitative Retinal Capillary Network and Myocardial Remodeling in Systemic Hypertension.

BackgroundThis study examined the associations between quantitative optical coherence tomography angiography (OCTA) parameters and myocardial abnormalities as documented on cardiovascular magnetic resonance imaging in patients with systemic hypertension.Methods and ResultsWe conducted a cross‐sectional study of 118 adults with hypertension (197 eyes). Patients underwent cardiovascular magnetic resonance imaging and OCTA (PLEX Elite 9000, Carl Zeiss Meditec). Associations between OCTA parameters (superficial and deep retinal capillary density) and adverse cardiac remodeling (left ventricular mass, remodeling index, interstitial fibrosis, global longitudinal strain, and presence of left ventricular hypertrophy) were studied using multivariable linear regression analysis with generalized estimating equations. Of the 118 patients with hypertension enrolled (65% men; median [interquartile range] age, 59 [13] years), 29% had left ventricular hypertrophy. After adjusting for age, sex, systolic blood pressure, diabetes, and signal strength of OCTA scans, patients with lower superficial capillary density had significantly higher left ventricular mass (β=−0.150; 95% CI, −0.290 to −0.010), higher interstitial volume (β=−0.270; 95% CI, −0.535 to −0.0015), and worse global longitudinal strain (β=−0.109; 95% CI, −0.187 to −0.032). Lower superficial capillary density was found in patients with hypertension with replacement fibrosis versus no replacement fibrosis (16.53±0.64 mm‐1 versus 16.96±0.64 mm‐1; P=0.003).ConclusionsWe showed significant correlations between retinal capillary density and adverse cardiac remodeling markers in patients with hypertension, supporting the notion that the OCTA could provide a non‐invasive index of microcirculation alteration for vascular risk stratification in people with hypertension.

Evaluation of Capillary and Other Vessel Contribution to Macular Perfusion Density Measured with Optical Coherence Tomography Angiography.

Parafoveal circulation of the superficial retinal capillary plexus is usually measured with vessel density, which determines the length of capillaries with circulation, and perfusion density, which calculates the percentage of the evaluated area that has circulation. Perfusion density also considers the circulation of vessels larger than capillaries, although the contribution of these vessels to the first is not usually evaluated. As both measurements are automatically generated by optical coherence tomography angiography devices, this paper proposes a method for estimating the contribution of vessels larger than capillaries by using a coefficient of determination between vessel and perfusion densities. This method can reveal a change in the proportion of perfusion density from vessels larger than capillaries, even when mean values do not differ. This change could reflect compensatory arterial vasodilatation as a response to capillary dropout in the initial stages of retinal vascular diseases before clinical retinopathy appears. The proposed method would allow the estimation of the changes in the composition of perfusion density without the need for other devices.

Retinal Microvascular Density Was Associated With the Clinical Progression of Parkinson's Disease.

BackgroundRetinal microvascular density has been studied in neurodegenerative diseases, whereas patients with Parkinson’s disease (PD) at different clinical stages have been rarely investigated. The present study aimed to evaluate the microvascular variations in superficial retinal capillary plexus (SCP) in patients with PD on different Hoehn-Yahr (H-Y) stages by optical coherence tomography angiography (OCTA), as well as determine their relationships with clinical parameters.MethodsIn total, 115 patients with PD and 67 healthy controls (HCs) were recruited. The PD group was divided into three groups based on the H-Y stage. The OCTA examination was performed in all participants, and the macular vessel density (m-VD), peripapillary vessel density (p-VD), and foveal avascular zone (FAZ) area were measured.ResultsThe m-VD in all regions, p-VD in center [6.1 (4.8, 6.95) mm–1 in healthy eyes vs. 5.1 (3.7, 6.4) mm–1 in patients], nasal inner (NI) [18.5 (17.8, 19.3) mm–1 in healthy eyes vs. 17.9 (17.1, 18.7) mm–1 in patients], temporal outer (TO) [19.6 (18.9, 20.2) mm–1 in healthy eyes vs. 19.3 (18.5, 19.7) mm–1 in patients] regions and FAZ area [0.36 (0.32, 0.39) mm2 in healthy eyes vs. 0.29 (0.26, 0.33) mm2 in patients] noticeably decreased in PD groups compared with HC (p < 0.05). Moreover, the FAZ area was suggested to decline significantly in patients with PD with H-Y I stage (p < 0.05), while it was more serious in the H-Y III stage in patients. Furthermore, we found that m-VD exhibited a significant negative correlation with age, disease duration, UPDRS scores, NMSS scores, and H-Y stage.ConclusionOCTA has the potential to non-invasively detect the microvascular changes in patients with PD with different clinical stages in vivo, and it may be a valuable tool to monitor the PD progression.

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

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

Analysis of Macular Retinal Thickness and Microvascular System Changes in Children with Monocular Hyperopic Anisometropia and Severe Amblyopia.

Objective To study the changes of macular retinal thickness and microvascular system in children with monocular hyperopic anisometropia and severe amblyopia using optical coherence tomography angiography (OCTA) and to explore the value of OCTA in the diagnosis and treatment of amblyopia. Methods Thirty-two children with monocular hyperopic anisometropia and severe amblyopia who were treated in the Department of Ophthalmology of the First Affiliated Hospital of Gannan Medical College from January 2020 to December 2020 were included in the study. Eyes with amblyopia (n = 32) served as the experimental group, and the contralateral healthy eyes (n = 32 eyes) served as the control group. All children underwent comprehensive ophthalmological examination including slit lamp, eye position, visual acuity, optometry, eye movement, intraocular pressure, ocular axis, and fundus examination to rule out organic lesions. Macular 6 mm × 6 mm scans were performed on both eyes of all subjects by the same experienced clinician using an OCTA instrument. After ImageJ processing, the vessel density, inner layer, and full-layer retinal thickness (RT) of superficial retinal capillary plexus (SCP) were obtained. All data were analyzed by SPSS21.0 software, and a paired t-test was used for comparison between groups. P < 0.05 was considered to indicate statistical significance. Results The vessel densities of macular SCP in the amblyopia and control groups were 47.66 ± 2.36% and 50.37 ± 2.24% in the outer superior, 49.19 ± 2.64% and 51.44 ± 2.44% in the inner inferior, 49.63 ± 2.51% and 51.41 ± 3.03% in the outer inferior, and 45.56 ± 3.44% and 50.44 ± 3.52% in the outer temporal regions, respectively. The vessel density of macular SCP in the amblyopia group was significantly lower than that in contralateral healthy eyes in the outer superior, inner inferior, outer inferior, outer temporal, and central regions. There was no significant difference between the two groups in the inner superior, inner nasal, outer nasal, and inner temporal regions. The macular RT in the amblyopia group and the control group is 90.38 ± 6.09 μm and 87.56 ± 5.55 μm in the outer temporal, respectively. The RT in the macular inner layer in the outer temporal region of the amblyopia group was thicker than that of the control group (P < 0.05). There was no significant difference in the other eight regions between the two groups. The whole macular RT in the amblyopia group was thicker than that in the control group in nine regions, and the central area of macular RT in the amblyopia and control groups was 229.06 ± 6.70 μm and 214.50 ± 10.36 μm, respectively. Conclusion The OCTA results showed the overall RT of macula in 9 areas in the amblyopia group was thicker than that in the control group, which could show that the macular retinal thickness can be a potential way to distinguish the children with monocular hyperopic anisometropia and severe amblyopia.

The role of optical coherence tomography angiography in the assessment of retinal microcirculation in thrombotic microangiopathy associated with malignant arterial hypertension

To evaluate retinal microcirculation using OCT-A imaging data in the group of patients with TMA associated with MAH. The study consisted of a qualitative and quantitative analysis of OCT-A data from 7 patients (14 eyes) with TMA associated with MAH and verified by renal biopsy. The control group included 7 healthy individuals (14 eyes). The following parameters were analyzed: area size of the foveal avascular zone FAZ, mm, vessel density (VD, %) and vessel skeleton density (VSD, %). The indicators were measured separately in the deep and superficial vascular plexuses and divided by localization into: the total density of the entire measured area, central density, density by quadrants (superior, inferior, nasal and temporal). All quadrants were subdivided into inner (corresponding to parafovea) and outer (corresponding to perifovea). Local foci of vascular attenuation of the deep retinal capillary plexus, pathological tortuosity of blood vessels in the deep and superficial retinal capillary plexuses were found in 100% of study group patients. Per-quadrant analysis of OCT-A finding in the macular zone revealed a statistically significant decrease in VD of the deep retinal capillary plexus (p<0.05). A direct correlation was found between glomerular filtration rate and the VD index in the outer inferior (r=0.567; p=0.034) and inner temporal quadrants (r=0.613; p=0.020) of the deep retinal capillary plexus, as well as the level of hemoglobin in blood serum and VD in inner temporal quadrant of the deep vascular plexus (r=0.596; p=0.025). Changes revealed with OCT-A are the symptoms of TMA in MAH patients spreading to the retinal microvasculature, mainly at the level of the deep retinal capillary plexus.