Evaluation of ocular arterial changes in glaucoma with color Doppler ultrasonography.

The purpose of this study was to evaluate hemodynamic changes of the retrobulbar vasculature caused by different intraocular pressures with color Doppler ultrasonography. Fifty normal eyes in 25 patients, 13 patients with normal tension glaucoma, and 19 patients with acute glaucoma and increased intraocular pressure (greater than 30 mm Hg) were enrolled in this study. In 15 of 19 patients with acute glaucoma patients, follow-up color Doppler ultrasonography was also undertaken after laser peripheral iridectomy when the intraocular pressure had returned to normal. The peak systolic velocity, end diastolic velocity, resistive index, time average maximum velocity, and pulsatility index were compared in different vessels, including the central retinal artery, lateral posterior ciliary artery, medial posterior ciliary artery, and ophthalmic artery in each orbit. The peak systolic velocity, end diastolic velocity, and time average maximum velocity of the central retinal artery were significantly lower (P<0.01) in acute glaucoma patients than in the control group. The resistive index and pulsatility index of the central retinal artery were significantly higher (P<0.01) in acute glaucoma patients than in the control group. The end diastolic velocity of the lateral and medial posterior ciliary arteries was significantly lower in patients with acute glaucoma than in the control group, and the resistive index and pulsatility index of both of these arteries were significantly higher (P<0.001) in patients with acute glaucoma than in the control group. However, no statistical significantly differences were found in the peak systolic velocity or time average maximum velocity in either of the posterior ciliary arteries; similarly, no statistically significant differences were noted in any of the parameters in the ophthalmic artery between the control group and the group with acute glaucoma. The pulsatility index of the central retinal artery and of the lateral and medial posterior ciliary arteries was significantly lower (P<0.01) in acute glaucoma patients after laser therapy than in acute glaucoma patients before laser therapy. The resistive index of both posterior ciliary arteries was also significantly lower (P<0.004) in acute glaucoma patients after laser therapy than before laser therapy. All parameters for all vessels examined among the normal subjects, the patients with normal tension glaucoma, and the patients with acute glaucoma after laser therapy when the intraocular pressure had returned to normal showed no statistically significant differences. Color Doppler ultrasonography is a good modality for both imaging and studying the hemodynamics of the perioptic nerve vessels.     

Effect of a nitric oxide donor on the ophthalmic artery flow velocity waveform in preeclamptic women.

OBJECTIVE: To evaluate the effects of an antihypertensive agent on the orbital circulation of preeclamptic women. METHODS: We studied the ophthalmic arteries of 10 healthy pregnant women and 10 women with severe preeclampsia by pulsed Doppler ultrasonography and evaluated the effect of transdermal isosorbide dinitrate, a nitric oxide donor, on preeclamptic women. RESULTS: The average pulsatility index and resistive index were significantly lower, whereas the average end-diastolic velocity, time-averaged mean peak velocity, and peak ratio, which quantifies characteristic changes in the ophthalmic artery flow velocity waveform, were higher in preeclamptic women. Transdermal isosorbide dinitrate significantly reduced the average end-diastolic velocity (P < .05) and peak ratio of the ophthalmic artery (P < .01), whereas it did not significantly affect other indices. CONCLUSIONS: Orbital circulation was altered in preeclamptic women. A nitric oxide donor affected orbital circulation. Peak ratio was a sensitive index for evaluating orbital circulation in preeclampsia.     

Color Doppler imaging of the eye: normal ranges,reproducibility, and observer variation.

Color Doppler ultrasonography has numerous potential applications in the diagnosis and monitoring of many ocular disease processes. One of its advantages over other investigative and diagnostic tests is its safety and repeatability. To be able to fully assess this technique it is important to have good control data and to know the reproducibility of the technique for each of the retrobulbar vessels. Color Doppler ultrasonography was performed on 80 volunteers, and normal ranges of blood velocity were calculated for the ophthalmic artery and for the central retinal artery and vein. Reduction in the peak systolic and end diastolic velocities in the ophthalmic artery and an increase in resistive index in the central retinal artery and vein were noted with advancing age. With regard to reproducibility of the retrobulbar vessels, 15 healthy persons were chosen at random and intra- and interobserver studies performed. The most reliable and reproducible vessels were the ophthalmic artery and central retinal artery and vein. Greater variation was noted in the posterior ciliary vessels, whereas the superior ophthalmic and vortex veins were unreliable in both detection and velocity measurement. The results provide normal ranges for future studies and demonstrate that reproducible results can be obtained for the orbital vasculature using color Doppler imaging.     

Color Doppler sonography of orbital and vertebral arteries in migraineurs without aura

PURPOSE: The objective of this study was to investigate whether the retrobulbar hemodynamics in the ophthalmic (OA), posterior ciliary (PCA), central retinal (CRA), and vertebral (VA) arteries are affected in migraineurs without aura. METHODS: The eyes of migraineurs without aura and those of healthy control subjects were evaluated during both headache and headache-free periods. Retrobulbar and vertebral blood flow velocities in the OA, PCA, CRA, and the extracranial part of the VA were measured bilaterally using color Doppler sonography. The peak systolic and end-diastolic flow velocities and the pulsatility (PI) and resistance (RI) indices were determined for all arteries. RESULTS: In total, we enrolled 30 migraineurs and 31 healthy control subjects. Statistically significant differences between headache-free migraineurs and control subjects were observed in the PI and RI of both right and left PCAs and in the RI of both right and left CRAs. The PI and RI of the left VA of the migraineurs were significantly lower during both headache and headache-free periods than were those of the control subjects. Among the migraineurs, the peak systolic and end-diastolic velocities of the left VA were increased during headache periods relative to those found during the headache-free periods. CONCLUSIONS: The retrobulbar circulation and flow hemodynamics in the left VA may be altered in both headache and headache-free periods in migraineurs without aura. The differences found between migraineurs and control subjects may implicate autonomic dysfunction in migraineurs.     

The effect of methyldopa on retinal artery circulation in pre-eclamptic gravidae.

OBJECTIVE: To evaluate the effect of methyldopa on retinal artery circulation in pre-eclamptic gravidae using color Doppler imaging and spectral analysis. METHODS: Fifty-three pre-eclamptic singleton gravidae of gestational age greater than 22 weeks were examined. Patients with sustained hypertension after 1-2 days hospital rest were treated with oral antihypertensive medication, 250-500 mg methyldopa, three to four times a day for a minimum of 5-7 days. The right central retinal arteries were insonated and Doppler waveform values were analysed before and after medication. RESULTS: The change of the maternal heart rate after methyldopa treatment was -3.96 +/- 7.88 beats per min (P = 0.0006). The change of fetal heart rate was not significantly altered. The change of the diastolic arterial blood pressure after treatment was -4.19 +/- 12.36 mmHg (P = 0.0169). In 36 gravidae, in whom hypotensive effects were noted after treatment with methyldopa, the increase in peak velocity, end-diastolic velocity and mean velocity of the retinal artery were 2.41 +/- 2.20 (P < 0.0001); 1.48 +/- 1.23 (P < 0.0001) and 1.70 +/- 1.42 (P < 0.0001), respectively. The decrease in pulsatility index of the retinal artery after treatment with methyldopa was -0.17 +/- 0.22 (P < 0.0001). In the remaining 17 gravidae, in whom no hypotensive effects were noted after treatment with methyldopa, the decrease in end-diastolic velocity and mean velocity were -1.50 +/- 1.70 (P = 0.0022) and -0.98 +/- 1.90 (P = 0.0488), respectively. The increase in pulsatility index was 0.34 +/- 0.30 (P = 0.0003). CONCLUSIONS: In pre-eclamptic gravidae in whom the hypotensive effects were noted after treatment with methyldopa, the mean velocity of the retinal arteries was significantly higher and the mean pulsatility index lower after treatment. We conclude that the hypotensive effect of methyldopa in pre-eclamptic gravidae is associated with a significant decrease in retinal artery vascular resistance.     

彩色多普勒血流显像对青光眼血流动力学研究

本文用美国Ａｃｕｓｏｎ－１２８ＸＰ彩色多普勒检测２４例原发开角青光眼（ＰＯＡＧ）、２７例低压青光眼（ＬＴＧ）及２０例正常人的眼动脉、视网膜中央动脉及睫状后短动脉的血流参数，测定收缩期血流峰值速度（Ｖｍａｘ）、舒张末期血流速度（Ｖｍｉｎ）平均血流速度（Ｖｍｅａｎ）及阻力指数（ＲＩ）、同时测血压及眼压。结果显示，ＰＯＡＧ和ＬＴＧ患者视网膜中央动脉的Ｖｍａｘ、Ｖｍｅａｎ及睫状后短动脉的Ｖｍａｘ、Ｖｍｉｎ、Ｖｍｅａｎ均显著降低，与对照组有显著差异（Ｐ＜０．０５）；而ＰＯＡＧ与ＬＴＧ两组间差异无显著性（Ｐ＞０．０５）。眼动脉的４个血流参数，ＰＯＡＧ、ＬＴＧ与对照组均无显著差异（Ｐ＞０．０５）；收缩压、舒张压三组间亦无显著差异（Ｐ＞０．０５）；而ＰＯＡＧ患者的眼压均值显著高于ＬＴＧ及对照组（Ｐ＜０．０１）。本文结果提示，ＰＯＡＧ和ＬＴＧ患者视网膜中央动脉、睫状后短动脉均存在血流动力学异常。使视盘的血液供应不良，从而导致结构和功能改变。     

Color Doppler sonographic mapping of pulmonary lesions: evidence of dual arterial supply by spectral analysis.

OBJECTIVE: Within pulmonary lesions, flow signals of pulmonary arteries can be discriminated from flow signals of central bronchial and peripheral bronchial arteries on color Doppler sonography. Our aim was to evaluate the evidence and frequency of different arterial supplies of pleural-based pulmonary lesions using qualitative and quantitative color Doppler sonography. METHODS: Forty-one patients with roentgenologically confirmed pleural-based pulmonary lesions were investigated by color Doppler sonography. The following parameters were investigated: (1) qualitative color Doppler sonographic evidence of vascularization, (2) quantitative color Doppler sonographic evidence of arterial flow signals (resistive index and pulsatility index), and (3) number of different arterial flow signals in 1 lesion by color Doppler sonographic mapping. RESULTS: We found no vascularization in 5 patients, sparse vascularization in 21, and pronounced vascularization in 15. Quantitative color Doppler sonographic parameters were as follows: mean pulmonary artery resistive index, 1.2; mean central bronchial artery resistive index, 0.5; mean peripheral bronchial artery resistive index, 0.7; mean pulmonary artery pulsatility index, 7.8; mean central bronchial artery pulsatility index, 0.7; and mean peripheral bronchial artery pulsatility index, 1.6. There was a significant difference between all types of flow signals for resistive and pulsatility index values but not between pulmonary and peripheral bronchial arteries (P = .068). In 41 patients, 57 different arterial flow signals were determined; 19 (46%) of these patients had 2 or more different arterial flow signals in a lesion. There was no significant difference between benign and malignant lesions regarding the number of flow signals. CONCLUSIONS: Evidence of at least a dual arterial supply can be found on quantitative color Doppler sonography in almost 50% of pulmonary lesions. A single spectral analysis is not suitable for characterization of the arterial supply of pulmonary lesions.     

Abnormally high resistive index of central retinal artery by ultrasound color Doppler in patients with viral chronic liver disease: correlation with worsening liver staging

Retrobulbar-ocular circulation provides an opportunity to assess the terminal circulation of the arterial cerebral tree. To evaluate whether retrobulbar circulation in patients with chronic liver disease is affected by adaptive mechanisms, we assessed by echo color Doppler, 1. The resistive-index of the central retinal artery, a terminal branch of the ophthalmic artery, and 2. the potential interrelationships with both liver staging and the most important splanchnic Doppler-parameters used to assess portal hypertension. The resistance index (RI) of the central retinal artery was obtained and compared with other classical Doppler parameters known to be affected by portal hypertension. The RI of the central retinal artery (CRA) was higher in cirrhotic patients than in controls or subjects with chronic hepatitis; it correlated with all the Doppler parameters of portal hypertension considered, with plasma renin-activity, and norepinephrine concentrations. Similarly to renal and splanchnic hemodynamics, retinal arterial circulation assessed by duplex Doppler seems to be affected by the histology of liver disease and by the overactivity of vasoconstrictor systems.     

彩色多普勒超声对高度近视眼血流动力学研究

目的:研究高度近视眼血流动力学及其在近视眼病理改变机制中的作用。方法:应用ATL超9型彩色多普勒诊断仪对26例高度近视眼、17例轻中度近视眼及26例正常对照眼的眼动脉(OA)、视网膜中央动脉(CRA)、睫状后动脉(PCA)进行检测。结果:高度近视组、轻中度近视组与正常对照组血流参数比较:OA血流参数无显著性差异(P>0.05)。CRA、PCA的收缩期(PSV)、舒张期(EDV)、平均血流速度(AV)流速均减低, CRA的阻力指数(RI)升高(P<0.05)。轻中度近视组与对照组比较,无显著性差异(P>0.05)。结论:高度近视眼患者CRA、PCA血流速度减低,表明视网膜及睫状血管系统血液灌注不足,可能是引起其病理性眼底改变的因素之一。彩色多普勒超声用于研究眼底血管、高度近视眼血流动力学变化具有临床意义。     

原发性高血压病患者眼球后动脉血流变化的多普勒超声观察

目的探讨高血压病患者眼动脉和视网膜中央动脉血流动力学变化,以寻找最敏感、重复性最好的血流参数指标。方法彩色多普勒超声检查55例原发性高血压病患者110只眼及50例正常对照组100只眼的眼动脉、视网膜中央动脉的血流参数,并对照分析。结果与对照组比较,高血压病患者眼动脉收缩期峰值流速（Vs）、舒张末期血流速度（Vd）降低,阻力指数升高（均P〈0．05）;视网膜中央动脉Vs、Vd降低,阻力指数、搏动指数升高（P〈0．05）;视网膜中央动脉与眼动脉血流速度比值降低（P〈0．01）。结论高血压病高眼球后动脉血流变化的多普勒超声参数为眼部病变的诊断和治疗提供可靠数据。     

Evaluation of differences between observers and automatic-manual measurements in calculation of Doppler parameters.

OBJECTIVE: We aimed to search for differences between observers and automatic and manual measurements in calculations of Doppler parameters. METHODS: The middle cerebral artery (MCA), central retinal artery, ophthalmic artery (OA), common carotid artery (CCA), vertebral artery (VA), popliteal artery (PA), interlobar renal artery (IRA), and arcuate renal artery (ARA) were evaluated in 20 healthy subjects bilaterally. Peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged maximum velocity (TAMAX), resistive index (RI), and pulsatility index (PI) were measured from the same spectrum manually by 3 observers and automatically. Results of 4 measurements were compared by analysis of variance and Pearson tests. RESULTS: The comparison of the 4 measurements revealed significant differences for most parameters except TAMAX of the OA, VA, and ARA and PSV, EDV, and PI of the PA. An automatic calculator yielded lower PSV, RI, and PI values (except the MCA and PA) and higher EDV values compared with manual measurements. The magnitudes of difference were in the range of 1% to 16% for velocities and 4% to 14% for RI and PI. The means of difference were 3.185 cm/s for PSV of the CCA and 0.054 for RI of the IRA. Correlation was high for PSV, EDV, and TAMAX in all arteries (except TAMAX of PA) and relatively low for PI and RI in most of the arteries. CONCLUSIONS: Although our study was performed on healthy subjects, our results showed that, in most cases, readers and the automatic approach disagreed on evaluation of Doppler parameters. This may be important in preventing false diagnoses in cases with Doppler values close to upper limits and may necessitate establishment of new limits for each method.     

Doppler measurement of blood flow velocities in extraocular orbital vessels in patients with obstructive sleep apnea syndrome

PURPOSE: We used color Doppler sonography to determine blood flow velocities in the extraocular orbital vessels of patients with obstructive sleep apnea syndrome (OSAS) and compared the results with those of healthy control subjects without OSAS. METHODS: Patients with OSAS were classified according to the apnea-hypopnea index (AHI) as having mild OSAS (AHI < 20) or severe OSAS (AHI > or = 20). The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistance index were measured in the ophthalmic artery (OA), central retinal artery (CRA), lateral short posterior ciliary artery, and medial short posterior ciliary artery using color Doppler sonography. Only 1 eye was measured in each study participant, and right and left eyes were chosen randomly. The blood flow velocities of patients with OSAS and those of control subjects were compared with the Kruskal-Wallis test and Wilcoxon's rank-sum test. RESULTS: The study comprised 30 patients (15 with mild and 15 with severe OSAS) and 20 healthy control subjects. Blood flow velocities were higher in most measured vessels in patients with OSAS than they were in the control subjects. Among patients with mild OSAS, the PSVs and EDVs in the posterior ciliary arteries were statistically significantly higher than those of the control group (p < 0.05), but those in the OA and CRA did not differ significantly between the mild OSAS group and the control group (p > 0.05). However, as the severity of OSAS increased, the PSVs and EDVs of the OA and CRA were also affected (p < 0.05). CONCLUSIONS: Color Doppler sonographic measurements of blood flow parameters in the orbital vessels may differ significantly between patients with OSAS and those without the syndrome. Therefore, OSAS should be considered in addition to other conditions when interpreting the results of color Doppler sonography of the extraocular orbital vessels if the clinical history points toward such a diagnosis.     

Color Doppler sonographic assessment of placental circulation in the first trimester of normal pregnancy.

Our aim was to study placental circulation during the first trimester of normal pregnancy. For this purpose, 108 single pregnancies from 4 to 15 gestational weeks were evaluated through conventional Doppler ultrasonography. The flow velocity waveforms from the retrochorionic arteries (spiral-radial arteries) and the umbilical artery were assessed using the peak systolic velocity, resistive index, and pulsatility index). Intervillous flow velocity waveform was evaluated from the maximum velocity. The earliest color signal from the retrochorionic circulation was registered at 4.5 weeks along with gestational sac visualization. The venous Doppler signal from the intervillous space and the Doppler signal from the umbilical artery were recorded with an embryo visible from the end of week 5 onward. The retrochorionic, intervillous, and umbilical peak systolic velocities increase, whereas the resistive and pulsatility indices decrease progressively during early pregnancy with a significant correlation with gestational age. Similarly, intervillous maximum velocity gradually increases throughout the first trimester of pregnancy. Despite some methodologic problems related to Doppler technology and the vessels studied color Doppler sonography appears to be an adequate tool to assess the physiologic changes in the placental circulation during early pregnancy.     

Duplex sonography of retro-orbital and carotid arteries in patients with normal-tension glaucoma

PURPOSE: To evaluate retrobulbar and carotid arterial hemodynamics in patients with normal-tension glaucoma using Doppler sonography. MATERIALS AND METHODS: Duplex sonography was performed in 41 patients with normal-tension glaucoma and 30 control subjects to evaluate resistance indices (RIs) in retro-orbital and carotid arteries. Mean values were compared using the independent t-test. The ratios of the RI in retro-orbital to RIs in the carotid arteries (CCA and ICA) and interocular and intercarotid differences in RI (DeltaRI) were also calculated. RESULTS: Is in the central retinal (CRA) and temporal and nasal posterior ciliary arteries (TPCA and NPCA) were statistically significantly greater in glaucomatous eyes (p < 0.001). Plaque formation in carotid arteries without significant stenosis was noted in 12% of patients and 10% of control subjects. Ratios of RI of CRA or TPCA or NPCA to that of CCA and the ratios of RI of CRA or NPCA to that of ophthalmic arteries (OA) were significantly greater in glaucomatous eyes. We also found that ratios of the RI of CRA or TPCA or NPCA to that of ICA and the ratio of the RI of OA to CCA were nearly equal to 1 in both patients and control subjects. We found no significant difference between interocular and intercarotid DeltaRIs in patients and control subjects. CONCLUSIONS: In patients with symmetric normal-tension glaucoma, duplex sonography showed an elevated RI in CRA and PCA. The Doppler evaluation of carotid arteries was useful.     

彩色多普勒超声监测斜视手术对眼血流动力学影

目的 :探讨斜视手术对眼血流动力学影响 ,评价多普勒超声监测眼动脉血供的临床价值。方法 :筛选斜视患者 51例 51只眼行 1或 2条水平直肌后徙 -截腱术。术前、术后 1周、 1个月分别用彩色多普勒超声诊断仪测量眼动脉 (OA)、睫状后动脉 (PCA)、视网膜中央动脉 (CRA)的收缩期血流速度峰值 (Vs)、舒张末期血流速度 (Vd)及阻力指数 (RI) ,比较血流改变并与 3 0例正常人对照。结果 :1.斜视眼术前患眼 OA、 PCA、 CRA血流参数与正常组比较无显著性意义 (P>0 .0 5) ;2 .斜视眼术后 1周眼动脉 Vs明显升高、 PI、 RI升高 (P<0 .0 5) ;3 .斜视眼术后 1个月 OA、PCA、 CRA各血流参数与术前比较 ,无显著性意义 (P>0 .0 5)。结论 :手术可以引起短期眼组织缺血 ,但随着手术激惹的消失及广泛侧枝循环的建立 ,1条或 2条水平直肌截断手术不会引起眼前节缺血 ,多普勒超声是评价眼血流动力学变化的敏感方法     

Transcranial Doppler sonography in the early stage of critical enteroviral infection.

OBJECTIVE: There is a high fatality rate in enteroviral infection with central nervous system involvement. Our aim was to investigate the change in intracranial blood flow to disclose the characteristic findings in the early stage of critical enteroviral infection. METHODS: We examined 27 patients in critical condition with enteroviral infection in our pediatric intensive care unit. We performed transcranial Doppler sonography within 12 hours of admission to the unit. The data were compared with those of a group of 11 patients with nonenteroviral encephalitis. RESULTS: The peak systolic, end-diastolic, and mean velocities of the critical enteroviral infection group were significantly higher than those of the control group (P < .05). Gosling pulsatility index and Pourcelot resistive index values for the right and left middle cerebral arteries (pulsatility index, [mean +/- SD], 0.68 +/- 0.22 and 0.77 +/- 0.19, respectively; resistive index, 0.48 +/- 0.01 and 0.52 +/- 0.01) in patients with critical enteroviral infection were significantly lower than those of patients with nonenteroviral encephalitis (pulsatility index, 1.10 +/- 0.30 and 0.98 +/- 0.22; resistive index, 0.62 +/- 0.01 and 0.60 +/- 0.01; P < .05). CONCLUSIONS: Low pulsatility index and resistive index values for cerebral blood flow were observed in the early stage of critical enteroviral infection. This characteristic finding of cerebral blood flow might be associated with the increased sympathetic discharge induced by a brain stem-involved systemic inflammatory response and dysfunction of autoregulation caused by the infection or other disorders of autoregulation that might cause severe or fatal complications.     

彩色多普勒超声对巩膜扣带术后球后血流动力学的研究

为研究巩膜扣带术后后睫状动脉（ＰＣＡ）、视网膜中央动脉（ＣＲＡ）球后血流动力学的改变，不同术式对眼部血流动力学的影响及ＰＣＡ、ＣＲＡ球后血流动力学改变的相关因素分析，对５０例孔源性视网膜脱离患者术前、术后不同时期行彩色超声多普勒检测。结果：巩膜扣带术后ＰＣＡ、ＣＲＡ的收缩期最大血流速度（Ｖｍａｘ）、舒张期末最小血流速度（Ｖｍｉｎ）较对照组下降，而阻力指数（ＲＩ）较对照组增加，经配对ｔ检验有显著性差异（Ｐ值＜０．０５）。环扎＋外加压可明显影响ＰＣＡ、ＣＲＡ的血流量，而单纯外加压术则无明显影响。ＰＣＡ、ＣＲＡ的Ｖｍａｘ改变与环扎带缩短率呈负相关。认为巩膜环扎术可导致眼血流量下降。     

Observer experience improves reproducibility of color Doppler sonography of orbital blood vessels

PURPOSE: The study investigated the reproducibility of orbital blood flow measurements with color Doppler imaging (CDI) at different stages of observer experience. METHODS: The subjects were 31 healthy volunteers and 2 sequential groups of 25 glaucoma patients each. Repeated blood flow measurements (usually 3 sets) in orbital vessels (ophthalmic artery, short posterior ciliary arteries, central retinal artery, and central retinal vein) were performed by the same observer in a single session in each subject. RESULTS: The parameters with the best reproducibility were the resistance index (mean coefficient of variation [COV], 3.3-8.8%), the peak systolic velocity (mean COV, 6.9-13.7%), the time-averaged velocity (mean COV, 7.2-16.0%), and the systolic acceleration time (mean COV, 8.8-12.3%). The mean COV was greater (9.9-20.3%) for the other arterial flow parameters (end-diastolic velocity and systolic acceleration) and for the venous flow velocities (maximum and minimum). The COVs of the parameters were improved by 20-40% as the observer became more experienced in ophthalmic CDI. CONCLUSIONS: We confirm the general reliability of CDI measurements in orbital vessels and show that observer experience improves reproducibility. It appears, however, that observer performance in these measurements is vessel specific.     

Doppler sonographic studies on the ophthalmic and central retinal arteries in the gravid woman.

The aim of this study was to establish normative data as gestation advances for pulsed Doppler evaluation of both the ophthalmic artery and the central retinal artery. After measuring intraocular pressure and blood pressure, pulsed Doppler ultrasonographic examination was performed on the ophthalmic and central retinal arteries in both eyes of 125 normal pregnant women. Nomograms, with 95% prediction intervals, have been generated for the Doppler indices, reflecting blood flow in both the ophthalmic and the central retinal arteries. The use of this technique in the management of pregnancy induced hypertension can now be better evaluated.     

Hemodynamic factors affecting uterine artery Doppler waveform pulsatility in sheep.

Quantitative analysis of vascular resistance from the Doppler time-velocity waveform relies on measuring arterial pulsatility. However, input pressure waveform pulsatility, impedance, and resistance have all been found to effect artery flow waveform pulsatility in circulatory mathematic models and in umbilical sheep preparations in vivo. The present study used an in vivo sheep preparation to determine that embolization of the uteroplacental circulation and maternal angiotensin II administration caused changes in the uterine Doppler time-velocity waveform pulsatility that were dependent on input pressure waveform pulsatility, fundamental impedance, and resistance changes. Uteroplacental vascular embolization increased vascular resistance and the uterine artery Doppler waveform resistive index; the mean component of flow (mean pressure/resistance) decreased. Decreased uterine artery Doppler resistive index occurred despite angiotensin II-induced vasoconstriction and increased vascular resistance because the pulse component of flow (pulse pressure/impedance) decreased.