Arterial stiffness shown by the cardio-ankle vascular index is an important contributor to optic nerve head microcirculation

Determination of Peak Oxygen Uptake in Patients with Acute Myocardial Infarction: The Role of Arterial Stiffness in Cardio-Vascular-Skeletal Muscle Coupling

The relationship between arterial stiffness and oxygen uptake (VO2) in patients with acute myocardial infarction (AMI) remains unclear. We aimed to investigate this relationship and factors contributing to VO2 in patients with AMI. The role of arterial stiffness in cardio-skeletal muscle coupling during exercise was then elucidated. Upon discharge, we measured exercise capacity using cardiopulmonary exercise testing (CPX), assessed arterial stiffness with the cardio-ankle vascular index (CAVI), and determined body composition to assess the skeletal muscle mass of 101 patients with AMI. Patients were categorized based on their CAVI scores into three groups: (i) normal (CAVI: ≤7.9), (ii) borderline (CAVI: 8.0-8.9), and (iii) abnormal (CAVI: ≥9.0). Subsequently, VO2 was compared among these groups. The relationship between the CAVI and VO2 Peak during CPX and factors contributing to VO2 Peak were investigated. The abnormal CAVI group had a significantly lower VO2 Peak than the normal and borderline groups. The CAVI was associated with VO2 Peak. Furthermore, the CAVI was found to be a factor contributing to VO2 Peak. These findings suggest that arterial stiffness in tissue blood distribution and blood supply causes systemic exercise limits in patients with AMI. This suggests that arterial stiffness plays a significant role in cardio-vascular-skeletal muscle coupling.

Retinal Vessel Pulsatile Characteristics Associated With Vascular Stiffness Can Predict the Rate of Functional Progression in Glaucoma Suspects

Purpose

Tissue stiffening and alterations in retinal blood flow have both been suggested as causative mechanisms of glaucomatous damage. We tested the hypothesis that retinal blood vessels also stiffen, using laser speckle flowgraphy (LSFG) to characterize vascular resistance.

Methods

In the longitudinal Portland Progression Project, 231 eyes of 124 subjects received LSFG scans of the optic nerve head (ONH) and automated perimetry every 6 months for six visits. Eyes were classified as either "glaucoma suspect" or "glaucoma" eyes based on the presence of functional loss on the first visit. Vascular resistance was quantified using the mean values of several instrument-defined parameterizations of the pulsatile waveform measured by LSFG, either in major vessels within the ONH (serving the retina) or in capillaries within ONH tissue, and age-adjusted using a separate group of 127 healthy eyes of 63 individuals. Parameters were compared against the severity and rate of change of functional loss using mean deviation (MD) over the six visits, within the two groups.

Results

Among 118 "glaucoma suspect" eyes (average MD, -0.4 dB; rate, -0.45 dB/y), higher vascular resistance was related to faster functional loss, but not current severity of loss. Parameters measured in major vessels were stronger predictors of rate than parameters measured in tissue. Among 113 "glaucoma" eyes (average MD, -4.3 dB; rate, -0.53 dB/y), higher vascular resistance was related to more severe current loss but not rate of loss.

Conclusions

Higher retinal vascular resistance and, by likely implication, stiffer retinal vessels were associated with more rapid functional loss in eyes without significant existing loss at baseline.

Tooth Loss and Carotid Intima-Media Thickness in Relation to Functional Atherosclerosis: A Cross-Sectional Study

Structural arterial stiffness can be evaluated with carotid intima-media thickness (CIMT). Functional arterial stiffness can be evaluated with cardio-ankle vascular index (CAVI). A positive association between CIMT and tooth loss has been reported, but no studies have evaluated the association between CIMT and tooth loss in relation to functional arterial stiffness (functional atherosclerosis). A cross-sectional study of 1235 Japanese individuals aged 40–89 years was conducted. Tooth loss was defined as being in the lowest tertile for the number of remaining teeth (≤20 in men and ≤19 in women). Functional atherosclerosis was defined as CAVI ≥ 9.0. Independent of known confounding factors, CIMT was positively associated with tooth loss only in participants without functional atherosclerosis. Adjusted odds ratios for tooth loss and a 1 standard deviation increment in CIMT were 1.27 (1.04–1.55) for participants without functional atherosclerosis and 0.99 (0.77–1.26) for participants with functional atherosclerosis. CIMT and functional atherosclerosis had a significant effect on tooth loss; the fully adjusted p-value for the interaction on tooth loss was 0.019. Independent of known confounding factors, CIMT is positively associated with tooth loss only in participants without functional atherosclerosis. This finding helps clarify the influence of the progression of arterial stiffness on tooth loss because the progression of structural atherosclerosis might have a beneficial influence on the maintenance of the microcirculation.

Dynamic Alterations in Blood Flow in Glaucoma Measured with Laser Speckle Contrast Imaging

PURPOSE

To assess the repeatability of blood flow velocity index (BFVi) metrics obtained with a recently Food and Drug Administration-cleared laser speckle contrast imaging device, the XyCAM RI (Vasoptic Medical, Inc), and to characterize differences in these metrics among control, glaucoma suspect, and glaucoma participants.

DESIGN

Prospective, observational study.

PARTICIPANTS

Forty-six participants: 20 control, 16 glaucoma suspect, and 10 glaucoma participants, 1 eye per participant.

METHODS

Key dynamic BFVi metrics-mean, peak, dip, volumetric rise index (VRI), volumetric fall index (VFI), time to rise (TtR), time to fall (TtF), blow-out time (BOT), skew, and acceleration time index-were measured in the optic disc, optic disc vessels, optic disc perfusion region, and macula in 4 imaging sessions on the same day. Intrasession and intersession variability were calculated using the coefficient of variation (CV) for each metric in each region of interest (ROI). Values for each dynamic BFVi variable were compared between glaucoma, glaucoma suspect, and control participants using bivariate and multivariate analysis. Pearson correlation coefficients were used to correlate each variable in each ROI with age, intraocular pressure, cup-to-disc ratio (CDR), mean deviation, pattern standard deviation, retinal nerve fiber layer thickness, and minimum rim width.

MAIN OUTCOME MEASURES

Coefficient of variation for the intrasession and intersession variability for each dynamic BFVi metric in each ROI and differences in each metric in each ROI between each diagnostic group.

RESULTS

Intersession CV for mean, peak, dip, VRI, VFI, TtR, and TtF ranged from 3.2 ± 2.5% to 11.0 ± 3.8%. Age, CDR, OCT metrics, and visual field metrics showed significant correlations with dynamic BFVi variables. Peak, mean, dip, VRI, and VFI were significantly lower in patients with glaucoma than in control participants in all ROIs except the fovea. These metrics also were significantly lower in glaucoma patients than glaucoma suspect patients in the disc vessels.

CONCLUSIONS

Dynamic blood flow metrics measured with the XyCAM RI are reliable, are associated with structural and functional glaucoma metrics, and are significantly different among glaucoma, glaucoma suspect, and control participants. The XyCAM RI may serve as an important tool in glaucoma management in the future.

Effects of aging and exercise habits on blood flow profile of the ocular circulation

Purpose

We examined the effects of aging and exercise habits on the ocular blood flow (OBF) and its profiles throughout the optic nerve head region and choroidal area. We hypothesized that exercise habits reduce the stiffness of vessels in the ocular circulation, which generally increases with aging.

Methods

Participants in a medical checkup program (698 males and 192 females aged 28 to 80 years) were categorized into 2 groups (with and without exercise habits) based on participant self-reporting and the definition of the Ministry of Health, Labor and Welfare of Japan (MHLW). OBF in the right eye was measured and analyzed using laser speckle flowgraphy. The blowout time (BOT), which is the time during which the blood flow is higher than half of the mean of the minimum and maximum signals during one heartbeat, was calculated as an index of the blood flow profile. BOT has been used as an indicator of the flexibility of blood vessels.

Results

BOT significantly decreased with aging. Neither the self-reported nor MHLW-based exercise habits significantly affected the ocular circulation.

Conclusion

These results indicate that the stiffness of the ocular vessels increases with aging, and this cannot be prevented by exercise habits.

Characteristics of laterality in the optic nerve head microcirculation obtained by laser speckle flowgraphy in healthy subjects

PURPOSE

To determine the characteristics of the laterality of the ocular microcirculation parameters obtained from laser speckle flowgraphy (LSFG) in the optic nerve head (ONH).

SUBJECTS AND METHODS

We reanalyzed a total of 240 healthy subjects (169 men, 71 women) who had participated in a medical checkup program. We analyzed the average mean blur rate (MBR), maximum MBR (Max-MBR), minimum MBR (Min-MBR), and area ratio of the blood stream (ARBS). As the pulse waveform parameters, we also calculated the skew, blowout score (BOS), blowout time (BOT), rising rate, falling rate, flow acceleration index (FAI), acceleration time index (ATI), resistivity index (RI), and beat strength over MBR (BOM). All parameters were compared between left and right eyes.

RESULTS

MBR-average, MBR-Max, MBR-Min, ARBS, skew, BOT, rising rate, falling rate, FAI, ATI, and ARBS did not differ significantly between the right and left eyes. The BOS in the right eyes was significantly lower than that of the left eyes, and the RI and BS in the right eyes were significantly higher than those of the left eyes. Similarly, for the whole of the ONH, the BOS in the tissue area (Tissue) and in the vessel area (Vessel) of the right eyes were significantly lower than those of the left eyes, and RI-Tissue, RI-Vessel, BOM-Tissue, and BOM-Vessel in the right eyes were significantly higher than those of the left eyes.

CONCLUSION

By using LSFG, we observed laterality of the BOS, RI, and BOM, all of which are pulse wave form parameters in the ONH.

Impact of acute dynamic exercise on vascular stiffness in the retinal arteriole in healthy subjects

Acute exercise can improve vascular stiffness in the conduit artery, but its effect on the retinal arterioles is unknown. The present study investigated the effects of acute dynamic exercise on retinal vascular stiffness. In experiment 1, we measured the cardio-ankle vascular index (CAVI), carotid artery intima-media thickness (carotid IMT), and retinal blood velocity by laser speckle flowgraphy in 28 healthy old and 28 young men (69 ± 3 and 23 ± 3 years, respectively). Pulse waveform variables, which were used as an index of retinal vascular stiffness, were assessed by retinal blood flow velocity profile analysis. In experiment 2, 18 healthy old and 18 young men (69 ± 3 and 23 ± 3 years, respectively) underwent assessment of pulse waveform variables after a 30-min bout of moderate cycling exercise at an intensity of 60% heart rate reserve. There was a significant difference in the baseline pulse waveform variables between the old and young groups. Pulse waveform variables in the retinal arteriole did not significantly change after acute dynamic exercise, whereas CAVI significantly decreased. These findings suggest that retinal vascular stiffness does not change by acute exercise. The effect of exercise on vascular stiffness in the retinal arterioles might be different from that in the conduit artery.

Ankle-brachial index and ocular diseases in a Russian population

Background

To assess potential associations between the ankle-brachial blood pressure index (ABI) and ocular disorders.

Methods

In the population-based cross-sectional Russian Ural Eye and Medical Study including 5,899 (80.5%) out of 7328 eligible participants aged 40+ years, the participants underwent a series of ocular and medical examinations including measurement of ABI.

Results

Blood pressure measurements of both arms and ankles were available for 3187 (54.0%) individuals. The mean ABI was 1.26 ± 0.19 (median:1.20; range: 0.61, 2.20). In multivariate analysis, a higher ABI was associated with younger age (P < 0.001; non-standardized regression coefficient B: −0.001; 95% confidence interval (CI): −0.002, −0.001), female sex (P < 0.001; B: 0.03; 95% CI: 0.02, 0.04), lower body mass index (P < 0.001; B: −0.004; 95% CI: −0.006, −0.003), lower waist-to-hip ratio (P = 0.01; B: −0.10; 95% CI: −0.17, −0.02), lower glucose serum concentration (P = 0.008; B: −0.005; 95% CI: −0.009, −0.001), lower prevalence of arterial hypertension (P < 0.001; B: −0.14; 95% CI: −0.16, −0.12), higher mean systolic blood pressure (P < 0.001; B: 0.003; 95% CI: 0.002, 0.003), and higher prevalence of any alcohol consumption (P < 0.001; B: 0.03; 95% CI: 0.02, 0.04). In that multivariate model, prevalence of glaucoma (P = 0.67) as a whole, open-angle glaucoma (P = 0.86) and angle-closure glaucoma (P = 0.54), stage of glaucomatous optic neuropathy (P = 0.57), prevalence of age-related macular degeneration (P = 0.88), prevalence and stage of diabetic retinopathy (P = 0.30, and P = 0.29, respectively), nuclear cataract (P = 0.32, and P = 0.41, resp.), cortical cataract (P = 0.33, and P = 0.92, resp.), subcapsular cataract (P = 0.74 and P = 0.60, resp.), and pseudoexfoliation (P = 0.44 and P = 0.47, resp.), intraocular pressure (P = 0.52), axial length (P = 0.20), and peripapillary retinal nerve fibre layer thickness (P = 0.55) were not significantly associated with the ABI.

Conclusions

In this ethnically mixed population from Russia, none of the major ocular diseases was associated with ABI suggesting that subclinical atherosclerosis is not markedly associated with the aetiology of these ocular disorders.

Real-Time Evaluation of Regional Arterial Stiffening, Resistance, and Ocular Circulation During Systemic Administration of Adrenaline in White Rabbits

Purpose

To evaluate continuous variations of ocular microcirculation by laser speckle flowgraphy and those of regional stiffening by pulse wave velocity (PWV) and vascular resistance under systemic adrenaline administration in rabbits.

Methods

Six 16-week-old male rabbits were evaluated. The mean blur rates in the retinal vessel (MBR-RV) and choroid (MBR-CH) were measured. We assessed blood pressure (BP), femoral and carotid vascular resistance, and the heart–ankle (ha)-PWV, heart–femoral (hf)-PWV, and femoral–ankle (fa)-PWV. Adrenaline (100, 300, and 1000 ng/kg) was intravenously administered over a 10-minute period during which the parameters were measured simultaneously every 2 minutes.

Results

The MBR-RV and MBR-CH values were dose-dependently increased by the adrenaline in parallel with increased BP. At the load of 100 ng/kg adrenaline, the ΔMBR-RV and ΔMBR-CH showed positive correlations with the variation rate in mean arterial blood pressure. Also, the variation rate in carotid vascular resistance and the Δfa-PWV and Δhf-PWV were significantly positively correlated with both the ΔMBR-RV and ΔMBR-CH. At the 300-ng/kg phase, the correlations between the Δha-PWV and both ΔMBR-RV and ΔMBR-CH were canceled; instead, the Δhf-PWV showed a significant negative correlation with the ΔMBR-RV and ΔMBR-CH. At the 1000-ng/kg phase, Δha-PWV again showed significant positive correlations with the ΔMBR-RV and ΔMBR-CH.

Conclusions

These results indicate the possibility that under a systemic administration of adrenaline in rabbits, not only the BP value but also the vascular resistance and arterial function are related to the variation in ocular microcirculation.

Translational Relevance

A real-time evaluation system of systemic regional arterial function and ocular microcirculation in rabbits was developed.

Longitudinal Testing of Retinal Blood Flow in a Mouse Model of Hypertension by Laser Speckle Flowgraphy

Purpose

The purpose of this study was to investigate the applicability of laser speckle flowgraphy (LSFG) for a longitudinal study of blood flow parameters in mice before, during, and after continuous infusion of angiotensin-II.

Methods

Normotensive C57BL/6J mice were imaged by LSFG at one (n = 22) or three sessions (n = 10). Two additional cohorts were imaged by LSFG before, during, and after continuous infusion of angiotensin-II by minipump for 2 or 4 weeks (n = 6 and 8, respectively). Retinal blood flow, vascular resistance, and total area of retinal vascular flow, a surrogate of vascular remodeling and vasoconstriction, were determined at each time point.

Results

During infusion of angiotensin-II for 2 weeks, decreased retinal blood flow and area of vascular flow, as well as increased vascular resistance, were observed. These changes were reversed 1 week after the end of angiotensin-II infusion. In mice infused with angiotensin-II for 4 weeks, decreased retinal blood flow and increased vascular resistance persisted at 6 weeks postinfusion, despite a decrease in blood pressure.

Conclusions

Arterial hypertension, induced by continuous angiotensin-II infusion, results in reduced retinal blood flow, increased vascular resistance, and decrease in area of intravascular blood flow within retinal arterioles and venules. Sustained vasoconstriction 6 weeks after the end of a 4-week period of angiotensin-II infusion may indicate vascular remodeling after a period of chronic hypertension.

Translational Relevance

Retinal LSFG is useful for serial investigation of blood flow in mouse models and provides a novel approach for translational studies on the microvascular effects of hypertension in vivo.

Increased cardio-ankle vascular index values in patients with acute branch retinal vein occlusion

Purpose:

Patients with retinal vein occlusions (RVOs) are at increased risk of cardiovascular disease. Arterial stiffness is an independent risk factor for cardiovascular events. Our aim is to evaluate the arterial stiffness in patients with acute branch retinal vein occlusion (BRVO) by using cardio-ankle vascular index (CAVI).

Methods:

This prospective study included 42 patients (18 male, mean age 57.5 ± 11.3) with acute BRVO and a matched control group (by age, sex, and presence of hypertension) with 70 (26 male, mean age 54.4 ± 9.4) patients. All patients and control subjects underwent complete ocular examination and CAVI measurement. BRVO was diagnosed based on clinical examination.

Results:

There were no significant differences between baseline clinical and demographic characteristics, echocardiographic measurements of left ventricular ejection fraction, systolic and diastolic blood pressure, and body mass index of the BRVO and control group. Both right and left CAVI values were found significantly higher in BRVO group (7.94 ± 1.53 vs 7.28 ± 1.25, P < 0.05 and 8.06 ± 1.41 vs 7.30 ± 1.26, P < 0.05, respectively). There were no significant difference in right and left ankle-brachial index values between the groups (1.05 ± 0.10 vs 1.06 ± 0.08, P = 0.46 and 1.04 ± 0.12 vs 1.05 ± 0.08, P = 0.46, respectively).

Conclusion:

Arterial stiffness is an important mediator of cardiovascular diseases. We found that CAVI which is a novel marker of the arterial stiffness is increased in patients with acute BRVO compared to controls.

Characterization of laser speckle flowgraphy pulse waveform parameters for the evaluation of the optic nerve head and retinal circulation

To characterize laser speckle flowgraphy (LSFG) pulse waveform parameters for ocular circulation evaluation, a multicenter, prospective, cross-sectional study was conducted in 111 eyes of 86 healthy Japanese individuals. Optic nerve head (ONH) tissue-area, vessel-area mean blur rate (MT and MV, respectively), and MT and MV pulse waveform parameters were obtained using LSFG and ONH structural parameters using planimetry. Multivariate linear mixed-effects modeled regression analysis identified factors contributing to MT- or MV-waveforms using age, gender, smoking history, body mass index, systolic and diastolic blood pressure, heart rate, intraocular pressure, axial length, disc, rim, and β-peripapillary atrophy areas, MT or MV, central retinal artery, and vein equivalents (CRAE and CRVE) as explanatory variables. MT- and MV-waveforms significantly correlated with one or more systemic factors, consistent with previous studies. Following confounding factor adjustment, MT-Skew significantly negatively correlated with β-PPA area (P = 0.026); MT- and MV-flow acceleration index positively correlated with CRAE, MT, and MV (P = 0.041–< 0.001), compatible with these parameters’ observed correlations to systemic factors. Significantly negative correlations of the blowout score and acceleration time index to CRAE partly conflicted with their correlations to systemic factors, and other waveform parameters showed little correlation to ocular factors. Thus, Skew and flow acceleration index assisted the in vivo ocular circulation characterization.

Ocular and Systemic Factors Affecting Laser Speckle Flowgraphy Measurements in the Optic Nerve Head

Purpose

To investigate the ocular and systemic factors related to glaucoma and to be adjusted for interindividual comparison of ocular blood flow measurement results by laser speckle flowgraphy (LSFG) obtained from the optic nerve head (ONH) in normal Japanese individuals.

Methods

A multicenter, prospective cross-sectional study was conducted. The ONH tissue-area and vessel-area mean blur rate (MT and MV) were evaluated using LSFG and ONH structural parameters using planimetric methods. Multivariate linear mixed-effects modeled regression analysis was used to identify the contributing factors to the MT and MV. The explanatory variables were age; gender; smoking history; body mass index; mean arterial pressure (MAP); heart rate; intraocular pressure; axial length (AL); disc, rim, cup, and β-peripapillary atrophy (β-PPA) areas; and central retinal artery and vein equivalents.

Results

In total, 195 eyes of 126 healthy individuals with an average age of 48.1 years were included. Multivariate analysis showed that MAP and disc area had a negative (P < 0.001) correlation, whereas β-PPA area had a positive correlation with MT (P = 0.010). Age and AL had a negative correlation (P = 0.001 and P = 0.011, respectively), whereas cup area had a positive correlation (P = 0.012) with MV.

Conclusions

Interindividual comparison of MT or MV must be adjusted for both systemic factors (blood pressure or age) and local ocular factors (AL and disc, cup, or β-PPA area).

Translational Relevance

Our results provided reference data on the LSFG measurement and are important in comparing ocular blood flow between individuals using LSFG.

Association between serum sodium level within normal range and handgrip strength in relation to hypertension status: a cross-sectional study

Serum sodium concentration within the normal range could act as an indicator of age-related changes such as decrease in muscle strength and impairment of capillary function. Since endothelial injury stimulates endothelial repair by enhancing CD34-positive cell production, the level of serum sodium may be inversely associated with that of circulating CD34-positive cells, thus indicating the degree of age-related endothelial injury. We conducted a cross-sectional study of 246 elderly Japanese men aged 60–69 years. Subjects were stratified by hypertension status because hypertension should act as a strong confounding factor for the analyses performed in this study. Serum sodium concentration was positively associated with handgrip strength in non-hypertensive subjects [standardized parameter estimate (β) = 0.29; p = 0.003], but not for hypertensive subjects (β = 0.01; p = 0.878), while it was inversely associated with circulating CD34-positive cell levels in non-hypertensive subjects [simple correlation coefficient (r) = − 0.28; p = 0.002] but not for hypertensive subjects (r = − 0.07; p = 0.454). For non-hypertensive elderly subjects, serum sodium concentration within the normal range is positively associated with handgrip strength and inversely associated with CD34-positive cells, thus partly indicating the degree of age-related endothelium injury. These associations could prove to be an efficient tool for clarifying the background mechanism governing the decrease in age-related muscle strength.

Influence of age and gender on the pulse waveform in optic nerve head circulation in healthy men and women

The influences of age and gender differences on the pulse waveform in the optic nerve head (ONH) in healthy adults, using laser speckle flowgraphy (LSFG) were evaluated. We studied 908 healthy subjects (men = 701, age: 50.0 ± 9.1, women = 208, age: 49.8 ± 9.5, p = 0.76), evaluating these pulse waveform parameters: the blowout score (BOS), blowout time (BOT), acceleration time index (ATI), and the rising and falling rates. The parameters were analyzed separately for the tissue, vessels, and throughout the optic nerve head (All). All parameters were compared between genders. We investigated which independent factors for the pulse waveform in the ONH is most strongly correlated with age. All sections of the BOS, BOT, ATI, and falling rate showed a significant gender difference. A univariate regression analysis revealed that BOT-Tissue showed the strongest correlation with age (r = −0.51). The factors contributing independently to the BOT-Tissue were gender, age, heart rate, mean arterial blood pressure, pulse pressure, spherical refraction, and estimated glomerular filtration rate. Among the subjects aged >41 years, the chronological changes of BOT-Tissue in the women were significantly lower than those in the men. We concluded that the pulse waveform in the ONH has clear differences between the genders and shows chronological changes.

The Relationship between Carotid Intima-Media Thickness and Ocular Circulation in Type-2 Diabetes

Purpose

To compare clinical findings, including ocular blood flow and intima-media thickness (IMT) of the carotid artery, in mild nonproliferative diabetic retinopathy (NPDR) and no diabetic retinopathy (NDR) patients, and to determine risk factors contributing to mild NPDR.

Methods

In 129 subjects (129 eyes) with type-2 diabetes patients and mild NPDR or NDR, standard statistical techniques were used to determine associations between clinical findings, including diabetes duration, blood levels of creatinine and hemoglobin A1c (HbA1c), central macular thickness (CMT; measured with optical coherence tomography), mean blur rate (MBR; measured with laser speckle flowgraphy), and ultrasound-measured carotid IMT.

Results

Diabetes duration, IMT, and CMT were significantly higher in the mild NPDR patients than the NDR patients (P=0.004, P=0.004, and P=0.003, respectively), while conversely, MBR in the overall optic nerve head (MBR-A) was lower in the mild NPDR patients. Furthermore, a logistic regression analysis showed that diabetes duration (OR, 1.11; P=0.006), diastolic blood pressure (OR, 0.93; P=0.025), heart rate (OR, 1.07; P=0.004), IMT (OR, 8.65; P=0.005), and CMT (OR, 1.03; P=0.007) were independent contributing factors to mild NPDR. Spearman's rank correlation test also showed that IMT was negatively correlated with MBR-A (P=0.011).

Conclusions

Increased IMT showed a close association with ocular ischemia in patients with type-2 diabetes and contributed to the presence of mild NPDR. These findings suggest that IMT may be an early biomarker of mild NPDR.

Effects of water drinking test on ocular blood flow waveform parameters: A laser speckle flowgraphy study

The water-drinking test (WDT) is a provocative test used in glaucoma research to assess the effects of elevated intraocular pressure (IOP). Defective autoregulation due to changes in perfusion pressure may play a role in the pathophysiology of several ocular diseases. This study aims to examine the effects of WDT on ocular blood flow (in the form of pulse waveform parameters obtained using laser speckle flowgraphy) to gain insight into the physiology of ocular blood flow and its autoregulation in healthy individuals. Changes in pulse waveform parameters of mean blur rate (MBR) in the entire optic nerve head (ONH), the vasculature of the ONH, the tissue area of the ONH, and the avascular tissue area located outside of the ONH were monitored over time. Significant increases in the falling rate of MBR over the entire ONH and its tissue area and decreases in blowout time (BOT) of the tissue area were observed only at 10 minutes after water intake. Significant increases in the skew of the waveform and the falling rate were observed in the vasculature of the ONH at 40 and 50 minutes after water intake, respectively. In the avascular region of the choroid, the average MBR increased significantly up to 30 minutes after water intake. Furthermore, the rising rate in this region increased significantly at 20 and 40 minutes, and the falling rate and acceleration-time index were both significantly increased at 40 minutes after water intake. Our results indicate the presence of effective autoregulation of blood flow at the ONH after WDT. However, in the choroidal region, outside of the ONH, effective autoregulation was not observed until 30 minutes after water intake in healthy study participants. These pulse waveform parameters could potentially be used in the diagnosis and/or monitoring of patients with glaucoma.

Differences in optic nerve head microcirculation between evening and morning in patients with coronary artery disease

PURPOSE

To determine whether differences or variation of blood flow in the ONH are independent risk factors for CAD.

METHODS

We studied 144 consecutive patients whose ocular blood flow in the ONH was measured in the evening and morning by LSFG. We analyzed the MBR throughout the ONH (MBR-A) and in the tissue (MBR-T) and vessels (MBR-V) in the ONH. We also evaluated the MBR-T, MBR-V, and MBR-A values obtained in the evening and morning and the variation (Δ) between evening and morning values in each group.

RESULTS

Twenty-three patients (16%) were diagnosed with CAD. The morning MBR-T and MBR-A values were significantly lower in these patients with CAD compared to the patients without CAD. ΔMBR-T in the CAD patients was significantly lower compared to that of the no-CAD patients. The logistic regression analysis was revealed that a high carotid artery plaque score, lower ΔDBP, and ΔMBR-T were identified as risk factors for CAD.

CONCLUSIONS

Ocular microcirculation obtained from LSFG may provide a window for detecting changes in microvasculature related to CAD.

Relationship between Metabolic Syndrome and Ocular Microcirculation Shown by Laser Speckle Flowgraphy in a Hospital Setting Devoted to Sleep Apnea Syndrome Diagnostics

PURPOSE

To clarify whether the incidence of metabolic syndrome (MetS) and the overlap of MetS components are affecting the ocular circulation shown by laser speckle flowgraphy (LSFG).

MATERIALS AND METHODS

We studied 76 consistent patients. Blowout score (BOS) and blowout time (BOT), which are the pulse waveform analysis parameters, and mean blur rate (MBR) using LSFG in the optic nerve head (ONH) and choroid were evaluated. Throughout, the ONH was separated out from the vessels and tissue for analysis and MBRs in the ONH were divided into four sections (superior, temporal, inferior, and nasal).

RESULTS

Thirty-two patients were diagnosed having Mets. MBR-Tissue (P = 0.003), MBR-All (P = 0.01), MBR-Choroid (P = 0.04), and BOS-Choroid (P = 0.03) were significantly lower in patients with MetS than in the patients without MetS. Multiple-regression analysis revealed the temporal side of MBR-Tissue and BOS-Choroid which were identified as factors contributing independently to the overlap of the MetS components. Multiple-regression analysis also revealed that the MetS components were identified to be factors independently contributing to the BOS-Choroid and temporal side of MBR-Tissue.

CONCLUSION

Our study clarified that the incidence of MetS and the overlap of the MetS components are significantly affecting the ONH and choroidal microcirculation.