The influences of gender and aging on optic nerve head microcirculation in healthy adults

Abstract

Potential differences in the nature of the influences of aging and gender on the optic nerve head (ONH) microcirculation, using laser speckle flowgraphy (LSFG) were evaluated. We studied 908 healthy subjects (men = 701, age: 50.0 ± 9.1 yrs, women = 208, 49.8 ± 9.5 yrs, p = 0.76). The average, maximum (Max), and minimum (Min) mean blur rate (MBR) in a heartbeat were evaluated. The parameters were analyzed separately for the tissue, vessels, and throughout the ONH (All). We investigated which MBR sections are correlated with gender and age by univariate and multivariate regression analyses. The Max MBR-All (r = −0.31) was most strongly correlated with gender (men = 1, women = 0). The Min MBR-All (r = −0.24) was most strongly correlated with age, followed by Min MBR-All (r = −0.20). The factors contributing independently to the Max MBR-All were gender (β = −0.15), pulse pressure, spherical refraction, ocular perfusion pressure, and red blood cell (RBC) count. The factors contributing independently to the Min MBR-Vessel were gender (β = −0.09), age (β = −0.25), body mass index, heart rate, and spherical refraction. The factors contributing independently to the Min-MBR-All were age (β = −0.22), heart rate, and RBC count. Our results revealed that gender differences influence the Max MBR, and aging influences the Min MBR. These correlations were stronger than that of average MBR. Laser speckle flowgraphy (LSFG), a noninvasive quantitative method for determining the ocular blood flow 1,2 , is based on the changes in the speckle pattern of laser light reflected from the fundus of the eye 3. LSFG is dependent on the movement of erythrocytes in the retina, the choroid, and the optic nerve head (ONH), and the mean blur rate (MBR) is an indicator of ocular blood flow 4,5. It was reported that measurements of MBR shows excellent repeatability with intraclass correlation coefficients and were barely affected by pupil dilation 6. The MBR is usually presented as the average value calculated from 118 MBR images (118 frames, 4-sec period) tuned to the cardiac cycle. Several studies revealed that gender differences and/or aging affect the average MBR in the ONH area 6-9 , indicating that age 7-9 and gender differences 6-9 are significantly correlated with the average MBR of the entire ONH area. However, the average MBR value is the mean value of the variation of the MBR during the systolic-to-diastolic cardiac cycle, and thus a decrease in the average MBR is caused by a decrease in the maximum MBR or the minimum MBR or both during the cardiac cycle. We hypothesized that the variations in the average MBR values that are caused by increasing versus decreasing the max. or min. MBR occur in clearly different manners. In addition, the influences of gender differences, aging, and other factors on the max., min., and average MBR in the ONH have not been established. We conducted the present study to clarify the influences of gender differences and aging on the max., min., and average values of the MBR parts in the ONH by examining a large...

Relative Retinal Blood Flow: A Novel and Informative Measure of Unilateral Retinal Vein Occlusion Severity

“…This difference is most likely explained by the higher age of BRVO patients when compared to the other groups and the well-documented finding that MBR decreases with age. 13,40 Notably, there was no correlation between RBF and age in either group, indicating that the metric is associated with disease-related differences rather than demographic changes. Age-related changes to MBR also highlight why it is useful to use the intrapatient control of patient's fellow eye when making comparisons of blood flow.…”

“…Analyses are additionally complicated by significant intersubject heterogeneity that goes beyond simple demographic differences. 27,28 Therefore the first aim of this study is to define a novel metric-relative blood flow (RBF)-and demonstrate how it effectively describes the impediment of retinal blood flow in patients with unilateral RVO. The second aim of this study is to compare this metric to known characteristics of RVOs and use it to help predict future outcomes.…”

Longitudinal effects of common carotid artery stenosis on ocular hemodynamics assessed using laser speckle flowgraphy in a rabbit model

“…We theorized that the variables of MBR waveform provide an indication of the systemic fluctuation of blood flow. A study showed that, in tissue regions, MBR max -increases while MBR min decreases with aging 23 , however, AC was not mentioned. In this study, we observed that the MBR max and MBR min increased while AC decreased in all regions over time.…”

Acute and Chronic Periocular Massage for Ocular Blood Flow and Vision: a Randomized Controlled Trial

“…Ageing increases the stiffness of ocular vessels and decreases the MBR. (23,24) We anticipated that short-term periocular massage can improve OBF variables, but there is no evidence for the improvement of OBF by chronic periocular massage at present.…”

“…The analysis method was similar to those reported previously. (23,24) The software program selected the optic nerve head using the automated definitive threshold (Figure 2). The following indices were calculated from the obtained data: MBR which reflects the velocity of the OBF, blow-out time (BOT), and blow-out score (BOS).…”