Abstract：
OBJECTIVE: The aim of the study was to obtain the values of oxygen saturation in retinal vessels and ophthalmic blood flow parameters in a healthy Caucasian population and assess whether the oximetry parameters are affected by the flow rate or the vascular resistance.
METHODS: The spectrophotometric retinal oximetry and colour Doppler imaging (CDI) of retinal vessels were successfully performed with 52 healthy subjects (average age 29.7 ± 5.6 years). The retinal oximeter simultaneously measures the wavelength difference of haemoglobin oxygen saturation in retinal arterioles and venules. The arteriolar and venular saturation in both eyes was measured. The peak systolic (PSV) end diastolic (EDV) velocities, resistive (RI) and pulsatility (PI) indices were obtained for both eyes using CDI in the ophthalmic artery. A paired t-test and two sample t-tests were used for statistical analyses. The correlation was assessed using the Pearson coefficient correlation.
RESULTS: The mean oxygen saturation level was 96.9 ± 3.0% for the retinal arterioles and 65.0 ± 5.1% for the retinal venules. The A-V difference was 31.8 ± 4.6%. The mean of the measured haemodynamic parameters was PSV 46.6 ± 9.4 cm/s, EDV 12.0 ± 3.5 cm/s, PI 1.68 ± 0.38 and RI 0.74 ± 0.05. No significant difference in oxygen saturation and haemodynamic parameters was found between the left and the right eyes or the dominant and non-dominant eye. The oximetry and ultrasound values were sex independent. The Pearson correlation coefficient demonstrated a significant yet weak negative correlation between A-V difference and RI (r = -0.321, p = 0.020).
CONCLUSIONS: A negative correlation between A-V difference and resistance index was observed, suggesting that reduced oxygen consumption may reflect the increased vascular tone of the ophthalmic vessels, which is likely determined by autoregulatory mechanisms.
METHODS: The spectrophotometric retinal oximetry and colour Doppler imaging (CDI) of retinal vessels were successfully performed with 52 healthy subjects (average age 29.7 ± 5.6 years). The retinal oximeter simultaneously measures the wavelength difference of haemoglobin oxygen saturation in retinal arterioles and venules. The arteriolar and venular saturation in both eyes was measured. The peak systolic (PSV) end diastolic (EDV) velocities, resistive (RI) and pulsatility (PI) indices were obtained for both eyes using CDI in the ophthalmic artery. A paired t-test and two sample t-tests were used for statistical analyses. The correlation was assessed using the Pearson coefficient correlation.
RESULTS: The mean oxygen saturation level was 96.9 ± 3.0% for the retinal arterioles and 65.0 ± 5.1% for the retinal venules. The A-V difference was 31.8 ± 4.6%. The mean of the measured haemodynamic parameters was PSV 46.6 ± 9.4 cm/s, EDV 12.0 ± 3.5 cm/s, PI 1.68 ± 0.38 and RI 0.74 ± 0.05. No significant difference in oxygen saturation and haemodynamic parameters was found between the left and the right eyes or the dominant and non-dominant eye. The oximetry and ultrasound values were sex independent. The Pearson correlation coefficient demonstrated a significant yet weak negative correlation between A-V difference and RI (r = -0.321, p = 0.020).
CONCLUSIONS: A negative correlation between A-V difference and resistance index was observed, suggesting that reduced oxygen consumption may reflect the increased vascular tone of the ophthalmic vessels, which is likely determined by autoregulatory mechanisms.
摘要：
目的：本研究的目的是获得健康白种人视网膜血管血氧饱和度和眼血流参数的值，并评估血氧参数是否受流速或血管阻力的影响。
方法：对52例健康受试者（平均年龄29.7±5.6岁）进行了视网膜血管的分光光度测量和彩色多普勒成像（CDI）。视网膜血氧计同时测量视网膜小动脉和小静脉中血红蛋白氧饱和度的波长差。测量两只眼睛的小动脉和静脉饱和度。收缩压峰值（PSV）舒张末期（EDV）速度，使用眼动脉中的CDI获得双眼的电阻（RI）和搏动（PI）指数。使用配对t检验和两个样本t检验进行统计分析。使用皮尔逊系数相关性评估相关性。
结果：视网膜小动脉的平均氧饱和度为96.9±3.0％，视网膜小静脉的平均氧饱和度为65.0±5.1％。A-V差为31.8±4.6%。测得的血液动力学参数的平均值为PSV46.6±9.4cm/s，EDV12.0±3.5cm/s,PI1.68±0.38和RI0.74±0.05。在左眼和右眼或优势和非优势眼之间没有发现氧饱和度和血液动力学参数的显着差异。血氧饱和度和超声值与性别无关。Pearson相关系数表明A-V差异与RI之间存在显着但弱的负相关（r=-0.321，p=0.020）。
结论：观察到A-V差异与抵抗指数之间呈负相关，这表明减少的耗氧量可能反映了眼血管的血管张力增加，这可能是由自动调节机制决定的。
方法：对52例健康受试者（平均年龄29.7±5.6岁）进行了视网膜血管的分光光度测量和彩色多普勒成像（CDI）。视网膜血氧计同时测量视网膜小动脉和小静脉中血红蛋白氧饱和度的波长差。测量两只眼睛的小动脉和静脉饱和度。收缩压峰值（PSV）舒张末期（EDV）速度，使用眼动脉中的CDI获得双眼的电阻（RI）和搏动（PI）指数。使用配对t检验和两个样本t检验进行统计分析。使用皮尔逊系数相关性评估相关性。
结果：视网膜小动脉的平均氧饱和度为96.9±3.0％，视网膜小静脉的平均氧饱和度为65.0±5.1％。A-V差为31.8±4.6%。测得的血液动力学参数的平均值为PSV46.6±9.4cm/s，EDV12.0±3.5cm/s,PI1.68±0.38和RI0.74±0.05。在左眼和右眼或优势和非优势眼之间没有发现氧饱和度和血液动力学参数的显着差异。血氧饱和度和超声值与性别无关。Pearson相关系数表明A-V差异与RI之间存在显着但弱的负相关（r=-0.321，p=0.020）。
结论：观察到A-V差异与抵抗指数之间呈负相关，这表明减少的耗氧量可能反映了眼血管的血管张力增加，这可能是由自动调节机制决定的。
