Parameters Of Retinal Microcirculation Research Articles

Retinal microcirculation changes in prediabetic patients with short-term increased blood glucose using optical coherence tomography angiography.

Retinal microcirculation alterations are early indicators of diabetic microvascular complications. Optical coherence tomography angiography (OCTA) is a noninvasive method to assess these changes. This study analyzes changes in retinal microcirculation in prediabetic patients during short-term increases in blood glucose using OCTA. To investigate the changes in retinal microcirculation in prediabetic patients experiencing short-term increases in blood glucose levels using OCTA. Fifty volunteers were divided into three groups: Group 1 [impaired fasting glucose (IFG) or impaired glucose tolerance (IGT)], Group 2 (both IFG and IGT), and a control group. Retinal microcirculation parameters, including vessel density (VD), perfusion density (PD), and foveal avascular zone (FAZ) metrics, were measured using OCTA. Correlations between these parameters and blood glucose levels were analyzed in both the fasting and postprandial states. One hour after glucose intake, the central VD (P = 0.023), central PD (P = 0.026), and parafoveal PD (P < 0.001) were significantly greater in the control group than in the fasting group. In Group 1, parafoveal PD (P < 0.001) and FAZ circularity (P = 0.023) also increased one hour after glucose intake. However, no significant changes were observed in the retinal microcirculation parameters of Group 2 before or after glucose intake (P > 0.05). Compared with the control group, Group 1 had a larger FAZ area (P = 0.032) and perimeter (P = 0.018), whereas Group 2 had no significant differences in retinal microcirculation parameters compared with the control group (P > 0.05). Compared with Group 1, Group 2 had greater central VD (P = 0.013) and PD (P = 0.008) and a smaller FAZ area (P = 0.012) and perimeter (P = 0.010). One hour after glucose intake, Group 1 had a larger FAZ area (P = 0.044) and perimeter (P = 0.038) than did the control group, whereas Group 2 showed no significant differences in retinal microcirculation parameters compared with the control group (P > 0.05). Group 2 had greater central VD (P = 0.042) and PD (P = 0.022) and a smaller FAZ area (P = 0.015) and perimeter (P = 0.016) than Group 1. At fasting, central PD was significantly positively correlated with blood glucose levels (P = 0.044), whereas no significant correlations were found between blood glucose levels and OCTA parameters one hour after glucose intake. A short-term increase in blood glucose has a more pronounced effect on retinal microcirculation in prediabetic patients with either IFG or IGT.

Early vascular damage in retinal microcirculation in arterial hypertension: the Czech post-MONICA study.

A total of 398 randomly selected individuals from an urban population aged 25-65 years, residing in Pilsen, Czech Republic, were screened for major cardiovascular risk factors. Retinal microcirculation was assessed using scanning laser Doppler flowmetry, with data evaluable in 343 patients. Complete data were available for 342 individuals divided into four groups based on blood pressure and control status of hypertension: normotensive individuals ( n = 213), treated controlled hypertensive individuals ( n = 30), treated uncontrolled hypertensive individuals ( n = 26), and newly detected/untreated hypertensive individuals ( n = 73). There was a tendency to higher wall thickness in treated but uncontrolled hypertensive patients (compared to normotensive and treated controlled hypertensive individuals). WLR was significantly increased in treated but uncontrolled hypertensive patients as well as in individuals with newly detected thus untreated hypertension or in patients with known but untreated hypertension. There was no difference in WLR in treated, controlled hypertensive patients compared with normotensive individuals. Our results show that an increased WLR, reflecting early vascular damage, was found in newly detected individuals with hypertension and in untreated hypertensive patients, reflecting early hypertension-mediated vascular damage. Early initiation of hypertension treatment may be warranted.

Sex Variations in Retinal Microcirculation Response to Lower Body Negative Pressure.

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. 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. No significant changes in retinal microcirculation were observed between the evaluated time points or across the sexes. 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.

Impaired retinal microcirculation in patients with non-obstructive coronary artery disease.

To quantitatively investigate alterations of retinal microcirculation in patients with non-obstructive coronary artery disease (NOCAD) using optical coherence tomography angiography (OCTA), and to identify the ability of retinal microcirculation parameters in differentiating coronary artery disease (CAD) subtypes. All participants with angina pectoris underwent coronary computed tomography angiography. Patients with lumen diameter reduction of 20-50% in all major coronary arteries were defined as NOCAD, while patients with at least one major coronary artery lumen diameter reduction ≥ 50% were recruited as obstructive coronary artery disease (OCAD). Participants without a history of ophthalmic or systemic vascular disease were recruited as healthy controls. Retinal neural-vasculature was measured quantitatively by OCTA, including peripapillary retinal nerve fiber layer (RNFL) thickness and vessel density (VD) of the optic disc, superficial vessel plexus (SVP), deep vessel plexus (DVP), and foveal density (FD 300). p<0.017 is considered significant in multiple comparisons. A total of 185 participants (65 NOCAD, 62 OCAD, and 58 controls) were enrolled. Except for the DVP fovea (p=0.069), significantly reduced VD in all other regions of SVP and DVP was detected in both the NOCAD and OCAD groups compared to control group (all p<0.017), while a more significant decrease was found in OCAD compared to NOCAD. Multivariate regression analysis showed that lower VD in superior hemi part of whole SVP (OR: 0.582, 95% CI: 0.451-0.752) was an independent risk factor for NOCAD compared to controls, while lower VD in the whole SVP (OR: 0.550, 95% CI: 0.421-0.719) was an independent risk factor for OCAD compared to NOCAD. Using the integration of retinal microvascular parameters, the area under the receiver operating characteristic curve (AUC) for NOCAD versus control and OCAD versus NOCAD were 0.840 and 0.830, respectively. Significant retinal microcirculation impairment, while milder than that in OCAD was observed in NOCAD patients, indicating retinal microvasculature assessment might provide a new systemic microcirculation observation window for NOCAD. Furthermore, retinal microvasculature may serve as a new indicator to assess the severity of CAD with good performance of retinal microvascular parameters in identifying different CAD subtypes.

Comparative analysis of optical coherent angiotomography in patients with primary open-angle glaucoma

Objective: to conduct a comparative analysis of the parameters of the optic nerve head, retinal ganglion cells and microcirculation parameters in patients with primary open-angle glaucoma (POAG) of various stages in achieving the target intraocular pressure using the method of optical coherence angiotomography. Material and methods. 87 patients (87 eyes) with POAG were examined. Group 1 — 26 patients (26 eyes) with stage I POAG, group 2 — 19 patients (19 eyes) with stage II glaucoma, group 3 — 24 patients (24 eyes) with stage III glaucoma. Group 4 (control group) — 18 patients (36 eyes) without signs of glaucoma. Optical coherence tomography was performed on patients, angio-OCT scans 6.4x6.4 of the macula and optic nerve head were used. Results. The thickness of the nerve fiber layer (RNFL) was 94.00±10.54 urn in patients with stage I POAG, 48.00±1.00 urn and 41.00±1.73 urn in patients with stage II and III POAG, respectively, moreover, a more sensitive indicator is the RNFL in the lower peri-papillary zone (Inf RNFL). The thickness of the layer of retinal ganglion cells (RGCs) in patients with stage I POAG was 96.33±4.62 urn, with II — 70.33±1.53 urn, with III — 64.33±11.93 urn. The density of blood vessels in the area of the optic disc differed from the norm in patients with stages II and III of POAG (42.23±4.95 and 35.10±1.80, respectively). Conclusion. In patients with different stages of POAG, the greatest differences were found in RNFL in the lower segment, the area of the neuroretinal rim, the values of focal and global GCS loss, and the density of the vascular bed in the lower half of the peripapillary zone.

Choriocapillary Flow Correlation with Axial Length in High Myopia - An Angiography Study with Optical Coherence Tomography.

To investigate parameters of retinal and choroidal microcirculation quantitatively with optical coherence tomography angiography (OCTA) in high myopic children, and to explore potential correlations with age, axial length (AL), spherical equivalent (SE), and central retinal thickness (CRT). En face angiograms were generated with an OCTA device and evaluated with automated density and flow analyzer algorithms. Perfusion parameters were correlated with age, AL, SE, and CRT using Spearman's rank correlation analysis. Repeatability and reproducibility of perfusion parameter measurements were calculated in a high myopic cohort. Repeatability and reproducibility of OCTA measurements were good, ranging from 3.6 - 6.5%. Strong positive correlation was identified between age and CRT (rho = 0.673, p = 0.00) as well as between AL and SE (rho = 0.844, p = 0.00). There was a strong negative correlation between AL and choriocapillary flow density (CCFD) (rho = - 0.612, p = 0.00), and a moderate negative correlation between age and superficial parafoveal retinal vessel density (SPRVD) as well as CCFD (rho = - 0.497, p = 0.013 and rho = - 0.483, p = 0.023, respectively). OCTA appears to be a reliable tool for the quantitative investigation of retinal and choroidal microcirculation in a high myopic pediatric cohort. CCFD reduction was associated with increasing AL in this cohort.

Reference values of retinal microcirculation parameters derived from a population random sample

Retinal microcirculation reflects retinal perfusion abnormalities and retinal arterial structural changes at relatively early stages of various cardiovascular diseases. Our objective has been to establish reference values for major functional and structural parameters of retinal microcirculation in a randomly selected urban population sample.A total of 398 randomly selected individuals from an urban population aged 25 to 65 years, resident in Pilsen, Czech Republic, were screened for major cardiovascular risk factors. Retinal microcirculation was assessed using scanning laser Doppler flowmetry (SLDF), with data evaluable in 343 patients. Of this number, complete data were available for 256 individuals free from manifest cardiovascular disease, diabetes and drug treatment for hypertension and/or dyslipidemia, constituting the reference value population.Juxtapapillary retinal capillary blood flow has increased significantly with age whereas vessel and luminal diameters have decreased. No sex differences in retinal microcirculation parameters have been found. Therefore, reference values for retinal microcirculation parameters have been established by age groups. Unattended automated office systolic BP, after adjusting for age, correlated significantly with wall-to-lumen ratio (WLR) and wall thickness (WT). Moreover, after adjusting for age and mean BP, a positive relationship has been found between carotid femoral pulse wave velocity and WT, WLR and wall cross-sectional area, indicating the interaction between micro- and macro-vasculature.In conclusion, our study is the first to provide reference values of retinal microcirculation parameters in a random Caucasian population sample. Our results have shown that, at the population level, the first structural changes in retinal microcirculation are those in lumen diameters. Of note, a close relationship between BP and vascular remodeling of retinal arterioles and between aortic stiffness and WLR of retinal arterioles suggests an interaction between micro- and macro-vasculature.

The relationship between the indicators of the retina condition and other target organ changes in uncomplicated essential hypertension

Background. Changes in retinal microcirculation are considered a subtle indicator of the other target organ damage in hypertension and might have prognostic value. Objective. To establish the relationship between diameters of retinal arterioles and venules, foveal avascular zone (FAZ) area, subfoveal choroid thickness with parameters of left heart and kidneys in middle-aged patients with essential hypertension (EH) stage I-II. Design and methods . A total of 115 people (86 males, 29 females) aged 45-59 years were examined and divided into 2 groups. The main group consisted of 70 patients with EH stage I or II. The control group comprised 45 normotensive practically healthy individuals. Patients with diabetes mellitus, impaired liver function, clinically significant ophthalmic pathology were not included. The following data were analyzed: anamnesis including smoking status; routine blood hemodynamic and biochemical parameters, serum procollagen III N-terminal propeptide (PIIINP); albumin-creatinine ratio in a single morning portion of urine, diurnal albuminuria; parameters of 24-h ambulatory blood pressure monitoring; quantitative electrocardiography (ECG) markers of left ventricular hypertrophy; transthoracic echocardiography; fundus state. Based on the scanning laser ophthalmoscopy, the central retinal arterial (CRAE) and venous (CRVE) equivalents, arteriovenous ratio (AVR) were calculated. Using the method of optical coherence tomography angiography, we determined the FAZ area and subfoveal choroid thickness. Statistical data were processed using the StatSoft Statistica 10. Results. Compared with normotensive individuals, patients with hypertension were characterized by lower values of CRAE (p = 0,009), larger FAZ area (p = 0,019), and comparable values of CRVE, AVR, subfoveal choroid thickness (p > 0,05 for each indicator). Correlation analysis showed that in hypertensive AVR correlated with low-density lipoprotein cholesterol level (r = -0,3; p < 0,05); FAZ area with female gender (r = 0,42; p < 0,05); FAZ area with PIIINP level (r = 0,3; p < 0,05); FAZ area with diurnal albuminuria (r = 0,37; p < 0,05); CRVE with R wave amplitude in aVL lead of ECG (r = 0,31; p < 0,05); CRAE with left atrial volume index (r = -0,3; p < 0,05); subfoveal choroid thickness with age (r= -0,3; p = 0,01). Conclusions. Middle-aged patients with uncomplicated EH are characterized by the lower CRVE values and larger FAZ area compared to normotensive individuals. In EH stage I-II, retinal microcirculation parameters are associated with indicators reflecting the other target organ damage, in particular, the left atrial volume index, R wave amplitude in aVL lead of the standard ECG, diurnal albuminuria, and serum PIIINP concentration.

Aortic stiffness is not only associated with structural but also functional parameters of retinal microcirculation

ObjectiveThe aim of the study was to test the hypothesis that alterations in large arteries are associated with microvascular remodelling and decreased retinal capillary blood flow. MethodsThe study group comprised of 88 patients with essential hypertension and 32 healthy controls. Retinal microcirculation was evaluated by scanning laser Doppler flowmetry. Macrovascular changes were assessed on the basis of arterial stiffness measurement (carotid-femoral pulse wave velocity), its hemodynamic consequences (central pulse pressure, augmentation pressure, augmentation index) and intima media thickness of common carotid artery. ResultsPulse wave velocity was inversely correlated to mean retinal capillary blood flow in hypertensive patients (R = −0.32, p < 0.01). This relationship remained significant in multivariate regression analysis after adjustment for age, sex, central systolic blood pressure (BP) and body mass index (β = −31.27, p < 0.001). Lumen diameter (LD) of retinal arterioles was significantly smaller in hypertensive then normotensive subjects (79.4 vs. 83.8, p = 0.03). Central and brachial systolic, diastolic and mean BPs were significantly correlated with LD and outer diameter of retinal arterioles. The relationship between LD and central BPs remained significant in multivariate analysis (β = −0.15, p = 0.03 for cSBP; β = −0.22, p = 0.04 for cDBP; β = −0.21, p = 0.03 for cMBP). Moreover, in a subgroup with cardiac damage central and brachial pulse pressure were positively associated with retinal wall thickness, wall cross sectional area, and wall to lumen ratio. ConclusionIn conclusion, the study provides a strong evidence that microcirculation is coupled with macrocirculation not only in terms of structural but also functional parameters.

REFERENCE VALUES OF RETINAL MICROCIRCULATION PARAMETERS IN A WHITE POPULATION RANDOM SAMPLE. CZECH POST-MONICA STUDY

Objective: Retinal microcirculation reflects retinal perfusion abnormalities and retinal arterial structural changes at relatively early stages of various cardiovascular diseases. Our objective was to establish reference values for major functional and structural parameters of retinal microcirculation in a randomly selected urban population sample.Design and method: A total of 398 randomly selected individuals from an urban population aged 25 to 65 years, resident in Pilsen, Czech Republic, were screened for major cardiovascular risk factors. Retinal microcirculation was assessed using scanning laser Doppler flowmetry (SLDF), with data evaluable in 345 patients. Of this number, complete data were available for 257 individuals free from manifest cardiovascular disease, diabetes and drug treatment for hypertension and/or dyslipidemia who made up the reference value population. Results: Retinal capillary blood flow (RCF) increased significantly with age whereas vessel and luminal diameters decreased. No sex differences in retinal microcirculation parameters were found. Reference values by age were established (see Table). A comparison between the reference value population and the diseased population (n = 88) derived from the same population sample found significant differences in age, BMI, BP, HbA1c, pulse wave velocity and prevalence of dyslipidemia, with the latter population consistently showing less favorable values. When comparing retinal parameters, after adj. for age, the only differences were found in vessel (reference value population: 103.5 ± 0.8 vs. diseased population: 107.0 ± 1.5 μm; p = 0.05) and luminal diameters (reference value population: 77.1 ± 0.5 vs. diseased population: 80.1 ± 0.9 μm; p = 0.007), with no differences in wall thickness or wall-to-lumen ratio, thus confirming that, at the population level, the first structural changes in retinal microcirculation are changes in lumen diameters. Conclusions: This is the first study providing reference values of retinal microcirculation parameters in a random white population sample. Our results show that, at the population level, the first structural changes in retinal microcirculation are those in lumen diameters.