Investigation of causes of sex-related differences in ocular blood flow in healthy eyes determined by laser speckle flowgraphy

Abstract

Sex-related differences are present in the systemic and ocular blood flow. However, the cause of the sex-related differences has not been determined. We investigated the ocular blood flow, represented by the mean blur rate (MBR), on the optic nerve head (ONH) determined by laser speckle flowgraphy in 138 males (63.9 ± 8.9 years) and 194 females (63.5 ± 9.4 years). The correlations between the MBR on the ONH and the clinical data were determined. The overall ONH-MBR was significantly higher in females than males (P < 0.001). In addition, the levels of the hemoglobin and hematocrit were significantly lower in females than in males (P < 0.001). The ONH-MBR was negatively and significantly correlated with the levels of the hemoglobin and hematocrit (both, P < 0.001). Multiple regression analyses showed that the sex (β = 0.248, P < 0.001) was an independent factor correlated with the ONH-MBR when the clinical examination data were not included in the analyses. However, when the clinical examination data were included, the hemoglobin level (β = −0.295, P < 0.001) was an independent factor that contributed to the ONH-MBR but the sex was not. We conclude that the sex-related differences in the hemoglobin level and the negative correlation between hemoglobin and the ONH-MBR are the causes of the sex-related differences in the ONH-MBR.

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

“…Fourth, we evaluated the spherical refraction and did not use the axial length. It has been reported that the axial length affects the results of MBR 34 , and we intend to evaluate the axial length in a future study. Finally, all of the subjects were Japanese, and it is unclear whether our results can be applied to non-Japanese populations.…”

Gender differences in the influence of obstructive sleep apnea on optic nerve head circulation

“…Aging has been identified as a factor contributing to a decrease in the MBR in the ONH 22–24 . It was also reported that the intima-media thickening revealed by ultrasonography reflects a decrease in all of the sections of the MBR in the ONH of individuals with diabetes mellitus 25 .…”

“…Our LSFG measurements revealed that the MBR-Tissue and MBR-All in the men were significantly lower than those in the women. Several reports regarding a survey of healthy subjects noted that gender differences affected the MBR in the ONH 24,34 . It has been reported that all sections of the MBR 24 , the MBR-vessel, and the MBR-All 34 of men were significantly lower than those of women.…”

“…Several reports regarding a survey of healthy subjects noted that gender differences affected the MBR in the ONH 24,34 . It has been reported that all sections of the MBR 24 , the MBR-vessel, and the MBR-All 34 of men were significantly lower than those of women. The LSFG measurements in our previous cross-sectional study of patients with some arteriosclerotic complications were similar to the measurements in these prior reports 24,34 .…”

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

“…In performing comparative clinical studies, it is important not only to establish the reference data of the MT or MV values in healthy eyes but also to identify the factors influencing the MT or MV measurement results, which should be adjusted for interindividual comparison. Luft et al 2 in European normal white individuals and Yanagida et al, 3 Iwase et al, 4 and Aizawa et al 5 in Japanese normal individuals, respectively, report normal values of MT and MV in each ethnicity and suggest that age, 2 , 4 gender, 3 , 4 blood pressure, 4 axial length (AL), 4 and intraocular pressure (IOP) 5 correlate with MT and that age, 2 , 5 gender, 3 – 5 blood pressure, 3 , 4 and IOP 5 correlate with MV, which should be adjusted for interindividual comparison. Because a laser speckle phenomenon is an interference event observed when lasers are scattered in a diffusing surface, 21 the LSFG-measured parameters such as MT should also be influenced by the reflection, absorption, and penetration depth of the laser in the target tissue.…”