Reproducibility of blood flow velocity measurements using colour decoded Doppler imaging

Evaluation of Ophthalmic Artery Doppler Parameters in Preeclamptic and Normotensive Pregnant Women

OBJECTIVE

 Preeclampsia, whose pathophysiology is still not fully elucidated today, is a pregnancy-specific disease that affects most organ systems in pregnant women, including the central nervous system. In this context, we aimed to investigate the effects of preeclampsia on blood flow in the ophthalmic artery of the eye, which is considered a part of the central nervous system.

MATERIALS AND METHODS

 This prospective, non-interventional cohort study was conducted between February 2022 and June 2022 at Umraniye Training and Research Hospital, Department of Obstetrics and Gynecology, Istanbul, Turkey. Forty-six normotensive healthy pregnant women constituted the control group and 46 preeclamptic pregnant women constituted the preeclampsia group. Prenatal follow-up and delivery of the participants were carried out in our clinic. First, an obstetric ultrasound was performed on all participants with the same ultrasound device and the same clinician. Then, Doppler measurements of the ophthalmic artery of both eyes were made by the same clinician using the linear probe of the same ultrasound. Both groups were compared in terms of the first peak of systolic velocity (PSV), second PSV, pulsatility index (PI), PSV ratio, end-diastolic velocity (EDV), resistance index (RI), and systolic/diastolic ratio (S/D) measurements of the ophthalmic artery. RESULTS : The first PSV, second PSV, PSV ratio, and EDV were significantly higher in the preeclampsia group than in the control group (p=0.001, p<0.001, p=0.019, p<0.001, respectively). According to the receiver operating characteristic analysis, the second PSV with a cut-off value of 43.75 cm/s was the most powerful ophthalmic artery Doppler parameter in detecting preeclampsia with 63% sensitivity and 63% specificity. No significant difference was found between the early and late onset or mild and severe preeclampsia groups in terms of ophthalmic artery Doppler parameters.

CONCLUSION

 Although the number of participants was too small to draw a definitive conclusion, the second PSV seems to be the most powerful parameter for the detection of preeclampsia. Studies with larger series are needed to determine the usability of ophthalmic artery Doppler parameters in the routine clinical diagnosis of preeclampsia and follow-up of the disease.

Comparison of Ocular Blood Flow in Glaucomatous Eyes and Nonglaucomatous Eyes at a Tertiary Hospital in South India: A Prospective Case-control Study

Aim

To compare the ocular blood flow in glaucomatous eyes and normal healthy eyes. This study compares open-angle glaucoma patients to healthy adults by measuring various parameters in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary artery (SPCA).

Materials and methods

A total of 50 glaucomatous eyes and 50 normal eyes were included in a prospective case-control study over 1 year. The color Doppler imaging (CDI) was conducted using a noninvasive linear multifrequency probe with a frequency range of 5-9 MHz. OA, CRA, and SPCA were measured for peak systolic velocity (PSV), end-diastolic volume (EDV), pulsatility index (PI), and resistivity index (RI).

Results

When compared with controls, PSV was decreased in all three vessels, with the results being remarkable only in CRA. The EDV also showed a remarkable decrease in all three vessels. Additionally, all three vessels showed significant increases in PI and RI except OA, p-value < 0.05.

Conclusion

Blood velocity is decreased, and resistive indices are increased in glaucomatous eyes compared with normal eyes. Variations in ocular blood flow could be a cause or consequence of glaucomatous optic neuropathy and are an important predictor of disease progression.

How to cite this article

Murugesan MAD, Venkat P, Basetti B. Comparison of Ocular Blood Flow in Glaucomatous Eyes and Nonglaucomatous Eyes at a Tertiary Hospital in South India: A Prospective Case-control Study. J Curr Glaucoma Pract 2024;18(2):45-50.

Quantitative evaluation of ocular vascularity and correlation analysis in patients with diabetic retinopathy by SMI and OCTA

AIMS

To find potential relation between retrobulbar vessels and fundus microvessels and to detect sensitive and effective clinical indicators in predicting the progress of diabetic retinopathy (DR), ocular hemodynamics were measured using superb microvascular imaging (SMI) and ultrawide-field optical coherence tomography angiography (UWF-OCTA).

METHODS

Observational, cross-sectional study evaluating ocular hemodynamics in patients with DR by SMI (Aplio i900, Canon Medical) and UWF-OCTA (BM-400 K BMizar, Tupai Medical Technology). The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive index (RI) of the central retinal artery (CRA), posterior ciliary artery (PCA), and ophthalmic artery (OA) were measured by SMI. UWF-OCTA evaluated the fundus vascular parameters. A correlation analysis was used to determine the correlation between SMI and UWF-OCTA parameters.

RESULTS

One hundred thirty-nine eyes of 139 diabetic patients were included: 29 without DR (NDR), 36 with mild to moderate nonproliferative DR (M-NPDR), 37 with severe NPDR (S-NPDR), and 37 with proliferative DR (PDR). PSV and EDV of retrobulbar vessels decreased from NDR to S-NPDR while increasing PDR. RI of OA showed a decreasing trend in the progression of DR, but other vessels didn't show the same trend. ROC curve analysis showed that CRAPSV, CRAEDV, PCAEDV, OAPSV, and OAEDV had diagnostic value distinguishing M-NPDR and S-NPDR. The correlation analysis observed a significant association between the SMI parameters of CRA and PCA and UWF-OCTA parameters. CRA hemodynamics were more associated with fundus vascular parameters, especially the retina, in the NDR group than in the M-NPDR group. In contrast, PCA consistently correlated with fundus vascular parameters, especially in the choroid, from the NDR to the M-NPDR group. However, OA showed a poor correlation with OCTA parameters.

CONCLUSION

The velocity of retrobulbar vessels, mainly the CRA, may serve as a valuable predictor for assessing the progress of DR. The use of SMI in diabetic patients may help identify patients at risk of developing retinopathy.

Ophthalmic artery Doppler in the complementary diagnosis of preeclampsia: a systematic review and meta-analysis

OBJECTIVE

To evaluate the accuracy of different parameters of the ophthalmic artery Doppler (OAD) in the complementary diagnosis of preeclampsia (PE).

METHODS

This meta-analysis adhered to the PRISMA guidelines. To investigate the mean difference in OAD values, peak systolic velocity (PSV), end-diastolic velocity (EDV), second systolic velocity peak (P2), resistance index (RI), pulsatility index (PI), and peak ratio (PR), between PE cases (overall and according to severity) and controls, random-effects meta-analyses were conducted for each Doppler parameter, with overall PE and mild and severe PE subgroups. Diagnostic performance and heterogeneity were evaluated with summary receiver operating characteristic (sROC) curves and 95% confidence intervals obtained with bivariate models.

RESULTS

Eight studies stratified the results into mild and severe or late and early PE, involving 1,425 pregnant women. PR and P2 had better diagnostic performance than the other indexes, with the PR of AUsROC at 0.885, the sensitivity of 84%, and specificity of 92%, with a low false-positive rate of 0.08 and the P2 with AUsROC of 0.926, the sensitivity of 85% and specificity of 88%. RI, PI, and EDV showed good performance and consistency across studies but lower AUsROC values of 0.833, 0.794, and 0.772, respectively.

CONCLUSION

Ophthalmic artery Doppler is a complementary tool with good performance for the diagnosis of overall and severe preeclampsia, with high and best sensitivity and specificity when using PR and P2 parameters.

Orbital and ocular perfusion in thyroid eye disease

Thyroid eye disease (TED) is characterized by enlargement of extraocular muscles, an increase in retrobulbar fat, orbital fibrosis, and fluctuations in plasma thyroid hormone levels in most patients, often associated with raised autoantibody titers. The occurrence of orbital space conflict compromises the orbital perfusion, unchecked progression of which results in irreversible loss of visual acuity and visual fields. The quantitative assessment of orbital perfusion can be done by measurement of blood flow velocities in the superior ophthalmic vein (SOV), ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery by color Doppler imaging. The retinal and choroidal microvasculature is studied by optical coherence tomography and optical coherence tomography angiography. The orbital and ocular perfusion fluctuates during the course of TED. Orbital congestion is reflected by the reduction or reversal of SOV flow and an increase in subfoveal choroidal thickness. The active phase is characterized by high blood flow velocities of the OA and CRA. The onset of dysthyroid optic neuropathy is associated with reduced arterial perfusion and reduction in parafoveal and peripapillary vascular density. Orbital decompression improves the SOV flow and decreases the resistivity index of CRA. Sequential evaluation of orbital hemodynamic changes can thus supplement the clinical scoring systems for monitoring and planning intervention in TED.

Role of ocular blood flow in normal tension glaucoma

Background

Normal tension glaucoma (NTG) is a multifactorial disease in the pathogenesis of which intraocular pressure (IOP)-independent factors play a key role.

Main text

There is considerable evidence that impairment of the ocular blood flow (OBF) is involved both in the onset and progression of this disease. With the development of the hypothesis of OBF in NTG, various imaging techniques have been developed to evaluate the OBF and blood vessels. Moreover, vascular dysregulation, which is a main factor in Flammer syndrome, was frequently observed in NTG patients. Disturbed OBF leads to increased oxidative stress, which plays an important role in the pathogenesis of glaucomatous optic neuropathy. These results suggested that IOP-independent management may provide alternative treatment options for NTG patients.

Conclusions

In this review, we mainly focus on the mechanisms of the abnormal OBF in NTG.

Performance of ophthalmic artery Doppler velocimetry in the complementary diagnosis of preeclampsia

OBJECTIVES

To calculate the accuracy (A) and establish the best cutoff value for ophthalmic artery (OA) Doppler velocimetry indexes in patients diagnosed with preeclampsia (PE), compared with healthy pregnant women.

METHODS

This prospective experimental study enrolled 268 women: 133 with PE and 135 healthy pregnant women. All patients were evaluated by OA Doppler sonography, bilaterally, to assess their pulsatility index (PI), resistance index (RI), peak systolic velocity (PVS), second peak systolic velocity (P2), end-diastolic velocity (EDV), and peak ratio (PR). Means were compared using Student's T-test. Receiver Operating Characteristics (ROC) curve was used to establish the cutoff value and estimate the sensitivity (S), specificity (Sp), accuracy (A) of all variables, and a significance of 95% was adopted.

RESULTS

ROC curve analysis showed that P2 and PR were superior to the other parameters for PE diagnosis. We tested two cutoff values: (1) using PR ≥0.70, obtained A: 88.72%, S: 81.95%, and Sp: 95.48% and (2) using PR ≥0.75, and A: 86.24%, S: 74.43%, and Sp: 99.24%. By adopting P2 ≥ 21.5 cm/s, we obtained A: 87.59%, S: 84.96%, and Sp: 90.22% and when the cutoff point was P2 ≥ 22 cm/s, there was a slight decrease in A to 86.46% and S to 81.20%, with Sp: 91.89.3%.

CONCLUSION

Ophthalmic artery Doppler demonstrated to be an effective and high-performance imaging method for the diagnosis of PE and the indexes P2 and PR demonstrated superior accuracy to the other Doppler parameters assessed. Higher performance occurred when the cutoff values with greater specificity were adopted, PR ≥ 0.75 and P2 ≥ 22 cm/s, considering that the proposed OA Doppler is to be a complementary method for preeclampsia.

Resistive index of ophthalmic artery as an imaging biomarker of hypertension-related vascular and kidney damage

Aim: Resistive index of ophthalmic artery (RI-OA) is associated with atherosclerotic diseases. The aim of this study was to evaluate the association of RI-OA and hypertension-related vascular and kidney damage. Materials and methods: Two-hundred and eighty hypertensive patients underwent evaluation of RI-OA, carotid atherosclerosis and level of 24 h albuminuria. Results: Albuminuria and carotid atherosclerosis were positively associated with RI-OA independently of other cardiovascular risk factors. Receiver-operating characteristic curve analysis allowed us to calculate a cut-off value of RI-OA >0.625, which would be suspicious about the existence of atherosclerotic disease. Conclusion: The ophthalmic vascular circulation allows to study connections between macro- and microcirculation in vivo. RI-OA could be a useful marker for a better stratification of the risk of developing kidney and cardiovascular disease.

Optic nerve sonography and ophthalmic artery Doppler velocimetry in healthy pregnant women: an Australian cohort study

PURPOSE

Maternal ocular sonography offers a window into cerebrovascular and intracranial pressure changes in pregnancy. This study aimed to determine the Doppler velocimetric variables of the ophthalmic artery, and the mean diameter of the optic nerve sheath (ONSD), in an Australian cohort of healthy pregnant women.

METHODS

A prospective observational cohort study of healthy women with uncomplicated singleton pregnancies in the third trimester was undertaken in a tertiary maternity service. A single prenatal ultrasonographic examination was performed on all participants, with a postnatal examination performed on a subgroup with uncomplicated deliveries.

RESULTS

Fifty women were examined at a mean gestation of 35 weeks. The mean ± SD Doppler variables in the ophthalmic artery were peak systolic velocity (PSV) 41.89 ± 13.13 cm/s, second peak velocity 20.63 ± 8.97 cm/s, end diastolic velocity 9.29 ± 5.13 cm/s, pulsatility index 1.97 ± 0.53, resistive index 0.78 ± 0.07, peak ratio (second peak velocity/PSV) 0.49 ± 0.12, while the mean ONSD was 4.34 ± 0.4 mm. None of these variables had a demonstrable relationship with gestation or mean arterial pressure (MAP), nor did the sheath diameter have a relationship with any of the Doppler variables.

CONCLUSIONS

The ocular sonographic variables observed in this population are similar to those reported in other cohorts. No clear relationship could be identified in this cohort between ophthalmic artery Doppler variables and the ONSD, and between each of these variables and gestation or MAP.

Optic nerve head microvascular changes after phacoemulsification surgery

BACKGROUND

To determine optic nerve head (ONH) microvascular changes detected by optical coherence tomography angiography (OCTA) and intraocular pressure changes (IOPs) after uncomplicated phacoemulsification surgery.

METHODS

The study was designed as a prospective observational study. Twenty-four eyes were included. Eyes with retinal vascular pathology, any type of age-related macular degeneration, IOP more than 21 mmHg, axial length less than 20 mm and more than 24 mm, corneal edema and cataracts that can disrupt images, and history of ocular surgery were excluded. Patients underwent OCTA imaging and IOP measurement preoperatively (baseline) and postoperatively (weeks 1 and 4). Vessel density % (VD) in the total disc, peripapillary, and inside disc were measured. IOP was measured with the applanation tonometer. Comparison of VD and IOP and correlation between VD and İOP change were determined.

RESULTS

VD was significantly increased in all quadrants in week 4 compared to those in week 1. In terms of VD and IOP, although there was no significant difference between week 1 and baseline, week 4 results were significantly different from baseline (p < 0.05 and p < 0.001, respectively). The IOP was significantly lower in week 4 (14.8 mmHg) than in week 1 (16.0 mmHg) (p < 0.001). There was a significant negative correlation between the inside disc and total VD and IOP at weeks 1 and 4.

CONCLUSION

Phacoemulsification surgery can result in a decrease in IOP and an increase in VD of the ONH.

Evaluating ocular blood flow

Studies have shown that vascular impairment plays an important role in the etiology and pathogenesis of various ocular diseases including glaucoma, age-related macular degeneration, diabetic retinopathy, and retinal venous occlusive disease. Thus, qualitative and quantitative assessment of ocular blood flow (BF) is a topic of interest for early disease detection, diagnosis, and management. Owing to the rapid improvement in technology, there are several invasive and noninvasive techniques available for evaluating ocular BF, with each of these techniques having their own limitations and advantages. This article reviews these important techniques, with a particular focus on Doppler Fourier domain optical coherence tomography (OCT) and OCT-angiography.

Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma

Glaucoma may be caused by an interplay of elevated intraocular pressure (IOP), vascular, genetic, anatomical, brain, and immune factors. The direct assessment of ocular hemodynam-ics offers promise for glaucoma detection, differentiation, and possibly new treatment modalities. All the methods currently in use to measure ocular blood flow have inherent limitations and measure different aspects of ocular blood flow. This review article attempts to provide detailed information on ocular perfu-sion pressure as well as an overview of the newly developed imaging technologies used to investigate ocular blood flow in glaucoma patients.

HOW TO CITE THIS ARTICLE

Mohindroo C, Ichhpujani P, Kumar S. Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma. J Curr Glaucoma Pract 2016;10(3):104-112.

Inter-device reproducibility of retrobulbar blood flow velocity measurements in healthy subjects using color Doppler imaging

PURPOSE

To evaluate the inter-device reproducibility of retrobulbar blood flow measurements obtained by two commercially available CDI (color Doppler imaging) devices.

METHODS

The right eyes of 10 healthy volunteers were investigated. Four examiners, namely two ophthalmologists and two radiologists, performed CDI examination of the ophthalmic artery, central retinal artery and temporal short posterior ciliary arteries using both CDI devices: ESAOTE MYLAB™ and SIEMENS ANTARES STELLAR PLUS™. The peak systolic velocity (PSV), the end-diastolic velocity (EDV) and the resulting resistivity index (RI) were averaged for 3 cardiac cycles. To evaluate the reproducibility between both device measurements, the Lin's concordance correlation coefficient (CCC) was used. CCC can be expressed as the product of Pearson's r (the measure of precision) and C_b (the measure of accuracy).

RESULTS

Results show that the inter-device reproducibility for CDI measurements is not acceptable since a poor degree of overall concordance (0.15<CCC<0.37) was obtained: accuracy was high (C_b > 0.71) but overall precision low (0.18< Pearson's r <0.47). Ophthalmologists and radiologists obtained similar results.

CONCLUSIONS

To evaluate the causal role of blood flow abnormalities in glaucoma, CDI analysis using different devices seems unreliable. CDI inter-device reproducibility seems unrelated to medical speciality of the examiners. However, to improve present results, the use of similar probes and standardized CDI instrument settings as well as a CDI images analysis by a single grader, might possibly improve the inter-device reproducibility when testing the retrobulbar blood flow velocity.

Ocular Blood Flow Autoregulation Mechanisms and Methods

The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and varied metabolic demand. In addition, ocular blood flow dysregulation has been demonstrated as an independent risk factor to many ocular diseases. For instance, ocular perfusion pressure plays key role in the progression of retinopathy such as glaucoma and diabetic retinopathy. In this review, different direct and indirect techniques to measure ocular blood flow and the effect of myogenic and neurogenic mechanisms on ocular blood flow are discussed. Moreover, ocular blood flow regulation in ocular disease will be described.

Usefulness of the Doppler flow of the ophthalmic artery in the evaluation of carotid and coronary atherosclerosis

BACKGROUND AND OBJECTIVES

There is little information about the relationship between the Doppler flow of the ophthalmic artery (OA) and carotid and coronary atherosclerosis. The aim of the investigation was to assess the clinical usefulness of the Doppler flow of the OA to estimate the severity of carotid and coronary atherosclerosis.

SUBJECTS AND METHODS

The study was a retrospective analysis of the findings in 140 patients (mean age: 60 years, male: 64%) who underwent coronary angiography (CA) for the evaluation of typical angina between July 2010 and October 2011 in our single center. The severity of coronary artery stenosis was based on the Gensini score (GS). Significant coronary artery disease (CAD) was defined as the obstruction of over 75% of the major coronary arteries confirmed with CA. The pulsed Doppler flow of the OA and carotid ultrasound were performed before CA.

RESULTS

The mean systolic velocity/mean diastolic velocity (MSV/MDV), pulsatile index and resistance index in the Doppler flow of the OA were identified as significant and independent correlations with carotid intima-media thickness, and MSV/MDV was identified to have a significant and independent correlation with the GS. MSV/MDV >2.1 was the independent predictor for significant CAD {odds ratio (OR) 3.8, 95% confidence interval (CI) 1.5-9.7, p=0.005} and carotid plaque (OR 2.8, 95% CI 1.1-7.0, p=0.028), after adjustment for CAD-associated factors.

CONCLUSION

The Doppler flow of the OA might be a useful predictor of the severity of carotid and coronary atherosclerosis.

Impact of intravitreal triamcinolone acetonide versus intravitreal bevacizumab on retrobulbar hemodynamic in patients with diabetic macular edema

PURPOSE

To evaluate and compare retrobulbar hemodynamic changes measured with color Doppler imaging (CDI) in diabetic patients receiving intravitreal triamcinolone acetonide (IVTA) versus bevacizumab.

METHODS

Patients with diffuse diabetic macular edema were assessed prospectively by CDI following intravitreal injection of triamcinolone acetonide (group I, 12 eyes) versus bevacizumab (group II, 14 eyes). CDI was used to measure the peak systolic velocity (PSV), end diastolic velocity (EDV) and the resistive index (RI) of the central retinal artery (CRA), ophthalmic artery (OA) and posterior ciliary arteries (PCA) one day preoperatively and one week postoperatively.

RESULTS

In group I, EDV of OA and CRA decreased significantly (p = 0.007 and 0.018, respectively). The PSV and RI of PCA decreased significantly (p = 0.035 and 0.002, respectively). In group II, both the PSV and EDV of the CRA decreased significantly (p = 0.000). Comparing the percentage of change in both groups, PSV of the CRA decreased significantly in group II (p = 0.034), while IVTA has more significant effect on the ophthalmic artery hemodynamic parameters as EDV decreased and RI increased significantly (p = 0.045 and 0.043, respectively)

CONCLUSION

Intravitreal injections of triamcinolone acetonide and bevacizumab have a significant effect on the ocular hemodynamic. The effect of bevacizumab is statistically significant on the PSV of CRA compared to IVTA.

Doppler study and evidences of perfusion changes in the ophthalmic artery of pregnant smokers

OBJECTIVES

To compare the ophthalmic artery (OA) perfusion of pregnant smokers and nonsmokers by Doppler indexes. Correlate these with the interval of last cigarette, cigarettes per day, years smoking and carbon monoxide expired (COex).

METHOD

Transversal study involving 70 pregnant smokers divided into 33 pregnant who smoked until 2 h: A group (AG) and B group (BG): 37, who smoked between 2 and 24 h before test. Control group (CG) was composed of 51 pregnant nonsmokers. Doppler indexes were assessed: PSV (Peak Systolic Velocity), EDV (End Diastolic Velocity), PI (Pulsatility Index), RI (Resistance Index) and PR (Peak Ratio). Groups were compared using ANOVA, Kruskal-Wallis test, Student's t test, Mann-Whitney and Pearson's correlation coefficient, whereas p < 0.05.

RESULTS

RI and PI were higher (p < 0.01) and PSV and EDV were lower (p < 0.05) in B group compared to other groups. A group presented higher PR (p < 0.01) compared to control. AG presented years of smoking, cigarettes per day, COex greater than BG and lower interval of last cigarette than BG.

CONCLUSIONS

The OA in pregnant smokers shows a biphasic pattern of perfusion correlated with the time of consumption of the last cigarette. There are signs of vasoconstriction and hypoperfusion to tobacco exposure between 2 and 24 and hyperperfusion in A Group compared to B Group.

Doppler velocimetry of the orbital vessels in pregnancies complicated by preeclampsia

Hypertension is one of the most common clinical complications during pregnancy. Preeclampsia, in particular, still accounts for high maternal and fetal morbidity and mortality. Hemodynamic studies have shown that general arteriolar vasoconstriction, which leads to hypoperfusion of target organs, including the eye area, remains the most significant pathological change in preeclampsia. Color Doppler imaging is the most appropriate and the commonly used method for the study of ocular circulation, especially during pregnancy. It enables the visualization and flow measurement of retrobulbar blood vessels. The aim of this review is to evaluate studies that investigated the role of Doppler velocimetry of the maternal orbital vessels, especially the ophthalmic artery, as a tool for the differential diagnosis of hypertensive disorders of pregnancy, for the assessment of the degree and severity of preeclampsia, and for the prediction of these disturbances. The analysis of these studies indicates that the Doppler variables are accurate in the differential diagnosis of hypertensive disorders and in assessing the severity and progression of the preeclampsia and may also be useful markers in the treatment and management of pregnancy-induced hypertension. We found no study evaluating the role of orbital vessels Doppler variables in predicting preeclampsia or in the prognosis of maternal-fetal adverse events.

Observations on degenerative changes within the optic nerve in patients with primary open glaucoma and arterial hypertension: 6-month follow-up

The authors aimed to determine the effect of the time of hypotensive drug administration on the progress of degenerative changes within the optic nerve in patients with hypertension and glaucoma. Two groups were included in the study: group A comprised patients-dippers taking drugs in the mornings, and group B comprised patients-nondippers taking drugs both in the mornings and in the evenings. After 6 months, group B showed significant drops in nocturnal diastolic blood pressure (BP) (month 1=73.27 mm Hg vs month 6=67.50 mm Hg), nocturnal mean BP (89.34 vs 84.65 mm Hg), and minimum diastolic BP (50.74 vs 44.03 mm Hg). Group B also showed significant reductions in nocturnal ocular perfusion pressure (43.0 vs 39.73), retinal nerve fiber layer thickness (131.31 vs 113.12 μm), and flow in the eye vessels. Taking hypotensive drugs in the evening may significantly decrease blood flow in the eye arteries, cause degenerative changes within the optic nerves, and result in greater loss in the field of vision.

Evaluation of the effects of acupuncture on blood flow in humans with ultrasound color Doppler imaging

Color Doppler imaging (CDI) can be used to noninvasively create images of human blood vessels and quantitatively evaluate blood flow in real-time. The purpose of this study was to assess the effects of acupuncture on the blood flow of the peripheral, mesenteric, and retrobulbar arteries by CDI. Statistical significance was defined as P values less than 0.05. Blood flow in the radial and brachial arteries was significantly lower during needle stimulation on LR3 than before in healthy volunteers, but was significantly higher after needle stimulation than before. LR3 stimulation also resulted in a significant decrease in the vascular resistance of the short posterior ciliary artery and no significant change of blood flow through the superior mesenteric artery (SMA) during acupuncture. In contrast, ST36 stimulation resulted in a significant increase in blood flow through the SMA and no significant change in the vascular resistance of the retrobulbar arteries. Additionally, acupuncture at previously determined acupoints in patients with open-angle glaucoma led to a significant reduction in the vascular resistance of the central retinal artery and short posterior ciliary artery. Our results suggest that acupuncture can affect blood flow of the peripheral, mesenteric, and retrobulbar arteries, and CDI can be useful to evaluate hemodynamic changes by acupuncture.

Doppler velocimetry of the ophthalmic artery: reproducibility of blood flow velocity measurements

OBJECTIVES

The aim of this study was to investigate the interobserver reliability for measuring ophthalmic artery Doppler indices.

METHODS

Healthy women (n = 30) were evaluated. The resistive index, pulsatility index, and peak ratio were determined by two independent observers who were blind to each other. A paired t test was used for the comparison of paired samples in the cases of replication between observers. Pearson product-moment correlation was used to study the relationship between the samples. The Bland-Altman graphic approach was used to investigate the agreement between observers.

RESULTS

No significant differences were found between the values obtained by the two independent observers for the resistive index and pulsatility index. The difference observed between the values obtained by the observers for the peak ratio was 0.02.

CONCLUSIONS

Doppler velocimetry is a reproducible technique for evaluation of the resistive index and pulsatility index. For analysis of the peak ratio, an interval of ±0.02 should be considered for the measurement.

Effects of the time of antihypertensive drugs administration on the stage of primary open-angle glaucoma in patients with arterial hypertension

Many patients with glaucoma suffer from arterial hypertension (AH). It has been proved that both AH and low blood pressure (BP) at night are important vascular risk factors for primary open-angle glaucoma (POAG). The aims of this study were to assess the severity of pathological changes within the optic nerve and characteristics of blood flow in selected arteries of the eyeball and orbit in patients with POAG and controlled hypertension, in relation to the time of hypotensive drugs administration. Eighty-eight patients with POAG and treated, controlled hypertension were examined. The patients were divided into two subgroups, consisting of group A (n = 43), in whom hypotensive drugs were dosed only in the morning and group B (n = 45), in whom hypotensive drugs were also taken in the evening. In patients who were taking hypotensive drugs also in the evening (group B), there was a statistically significant lower mean perfusion pressure at night, a greater visual field loss and reduced amplitude of evoked potentials. Our analysis showed significantly worse changes in the parameters relating to the optic nerve in patients taking hypertensive medicines in the evening and also significantly lower perfusion pressures at night.

Use of colour Doppler imaging in ocular blood flow research

The main objective of this report is to encourage consistent quality of testing and reporting within and between centres that use colour Doppler imaging (CDI) for assessment of retrobulbar blood flow. The intention of this review is to standardize methods in CDI assessment that are used widely, but not to exclude other approaches or additional tests that individual laboratories may choose or continue to use.

Agreement among three examiners of colour Doppler imaging retrobulbar blood flow velocity measurements

PURPOSE

To assess the agreement among three masked examiners on central retinal artery (CRA) and ophthalmic artery (OA) blood flow velocity measurements performed with colour Doppler imaging (CDI) in healthy volunteers.

METHODS

The study included 30 eyes of 15 healthy volunteers. Prior to the study, all examiners underwent intensive CDI training by an expert to facilitate uniformity in performing measurements according to a specific protocol. Following the eligibility visit, three masked examiners performed CDI measurements assessing the CRA and OA in both eyes of all subjects. All CDI images were analysed by a masked grader. Intraclass correlation coefficients (ICC) were calculated for peak systolic velocity (PSV) and end diastolic velocity (EDV) in the CRA and OA among the examiners. p-values < 0.05 were considered statistically significant.

RESULTS

The study included seven men and eight women (mean age 30.9 ± 4.5 years). In right eyes, ICCs for PSV and EDV in the CRA ranged from 0.917 to 0.961 and from 0.937 to 0.980, respectively. ICCs for PSV and EDV in the OA ranged from 0.802 to 0.926 and from 0.611 to 0.891, respectively. In left eyes, all ICCs for PSV and EDV were >0.9, both in the CRA and the OA. All p-values calculated for ICCs were statistically significant.

CONCLUSION

Expert training and execution of a specific protocol for CDI of ocular blood flow velocity measurements provide highly reproducible results in healthy volunteers. This is important for long-term studies assessing ocular hemodynamics, where multiple examiners may be involved.

Short-term effects of acupuncture on open-angle glaucoma in retrobulbar circulation: additional therapy to standard medication

Background. The relation between glaucoma and retrobulbar circulation in the prognosis has been indicated. Purpose. To investigate the effects of acupuncture on retrobulbar circulation in open-angle glaucoma (OAG) patients. Methods. Eleven OAG patients (20 eyes with OAG) who were treated by topical antiglaucoma medications for at least 3 months were enrolled. Acupuncture was performed once at acupoints BL2, M-HN9, ST2, ST36, SP6, KI3, LR3, GB20, BL18, and BL23 bilaterally. Retrobulbar circulation was measured with color Doppler imaging, and intraocular pressure (IOP) was also measured at rest and one hour after rest or before and after acupuncture. Results. The Δ value of the resistive index in the short posterior ciliary artery (P < .01) and the Δ value of IOP (P < .01) were decreased significantly by acupuncture compared with no acupuncture treatment. Conclusions. Acupuncture can improve the retrobulbar circulation and IOP, which may indicate the efficacy of acupuncture for OAG.

[Effect on ocular blood flow of Combigan® versus placebo in patients with ocular hypertension]

PURPOSE

This study was undertaken to compare the ocular haemodynamic effects of Combigan(®) versus placebo in patients with ocular hypertension (OHT).

METHODS

Thirty patients with OHT were included in a controlled, randomised, double blind study in two parallel groups; 15 were randomised to receive Combigan(®) and 15 to receive placebo for a period of 3 months. At baseline and at 3 months retrobulbar blood flowmeasurements of the ophthalmic artery (OA) and central retinal artery (CRA) were taken using colour Doppler imaging(CDI) ultrasound, concurrently with intraocular pressure (IOP).

RESULTS

Combigan(®) significantly reduced IOP after 3 months of treatment (P = 0.001), whereas placebo showed no significant change in IOP. The baseline haemodynamic parameters were similar between treatment and placebo groups. Patients treated with Combigan® showed a statistically significant decrease in CRA resistive index (P = 0.007).

CONCLUSIONS

Patients treated for 3 months with Combigan(®) showed a significant decrease of CRA resistive index that could be explained by the decrease in IOP.

Short-term effects of intravitreal bevacizumab (Avastin(®)) on retrobulbar hemodynamics in patients with neovascular age-related macular degeneration

PURPOSE

To evaluate the short-term effects of intravitreal bevacizumab on retrobulbar hemodynamics in patients with neovascular age-related macular degeneration (AMD).

METHODS

This study was carried out at Ataturk Training and Research Hospital 1st Ophthalmology Clinic, Ankara. Fourteen patients with neovascular AMD, who were treated with intravitreal injection of bevacizumab, were included in this study. Peak systolic velocity (PSV), end-diastolic velocity (EDV) and resistivity index (RI) were measured with colour Doppler imaging (CDI) in the ophthalmic artery, central retinal artery (CRA) and posterior ciliary artery.

RESULTS

The mean age of the 14 patients was 78 ± 9 (64-87). Of the 14 patients, eight were men and six were women. Colour Doppler imaging measurements of EDV (p = 0.015) and RI (p = 0.009) parameters of CRA revealed statistically significant difference among all three periods. End-diastolic velocity values decreased at the end of the 1st week and returned close to preoperative values at the end of the 1st month after the procedure. Also, EDV of posterior ciliary artery (PCA) decreased at the end of the 1st week and returned close to preoperative values at the end of the 1st month after the procedure. Resistivity index of PCA showed a temporary increase at the end of the 1st week and returned close to preoperative values at the end of the 1st month after the procedure.

CONCLUSION

Injection of bevacizumab decreased blood velocities of CRA and PCA and increased RI of CRA and PCA in the early postoperative period and returned to preoperative values at the end of the first month.

Ultrasound assessment of short-term ocular vascular effects of intravitreal injection of bevacizumab (Avastin(®) ) in neovascular age-related macular degeneration

PURPOSE

Angiogenic inhibitors, alone or combined with other therapies, are believed to represent a promising treatment for neovascularization in age-related macular degeneration (wet AMD). They can maintain or improve visual acuity (VA), at least for the first 2years. However, evolution to retinal atrophy cannot be ruled out and it may be useful to assess the effects of antiangiogenic therapy on retinal and choroidal circulation.

METHODS

We carried out a pilot study in 15 patients with wet AMD. Time-averaged mean blood flow velocities (BFVs) in the central retinal, temporal posterior ciliary and ophthalmic arteries (CRA, TPCA and OA) were measured by ultrasound imaging before and 4weeks after a single intravitreal injection of 1.25mg bevacizumab in 0.05ml. Patients underwent two ophthalmic examinations, before and 4weeks after injection, including VA measurement and optical coherence tomography (OCT3) examination.

RESULTS

  In treated eyes, bevacizumab injection was followed by a significant improvement in VA (from 20/125 to 20/80; p=0.0214), and a decrease in mean central macular thickness (from 392±96μm to 271±50μm; p=0.0038). Mean BFV decreased by 10% in the CRA (p=0.0226), 20% in the TPCA (p=0.0026) and 20% in the OA (p=0.0003). No effect was observed in fellow eyes.

CONCLUSIONS

  Intravitreal bevacizumab acutely improved VA and reduced central macular thickness in wet AMD. Ultrasound imaging revealed that BFVs decreased in all retrobulbar arteries, suggesting that after local diffusion, bevacizumab exerts a short-term regional effect. Bevacizumab might therefore induce hypoperfusion of the whole eye, which may correspond to a vascular side-effect.

Waveform of ophthalmic artery Doppler flow predicts the severity of systemic atherosclerosis

BACKGROUND

Doppler imaging of ophthalmic artery (OA), the first major branch of the internal carotid artery, provides anatomical advantages due to the vertical angle to the body surface and absence of ultrasonic obstacles. It was hypothesized that the Doppler waveform indices of OA correlate with severity of systemic atherosclerosis.

METHODS AND RESULTS

The study subjects were 180 patients who underwent cardiac catheterization and OA Doppler imaging (90 patients with coronary artery disease (CAD) and 90 control patients). The ratio of stroke volume to pulse pressure, an index of arterial compliance, was closely associated with the ratio of systolic to diastolic mean velocity (Sm/Dm) in OA. The level of Sm/Dm increased in proportion with the increase in number of stenosed coronary arteries (0-vessel disease 2.1+/-0.3, 1-vessel disease 2.3+/-0.3, multi-vessel disease 2.6+/-0.5, P<0.0001). The Sm/Dm level in OA correlated positively with age, pulse pressure, pulse wave velocity, resistive index and pulsatility index in OA. The best Sm/Dm cut-off to predict CAD was 2.3, and patients with Sm/Dm >2.3 had 8.0-fold risk for CAD.

CONCLUSIONS

The waveform indices of OA are clinically useful for evaluating the severity of CAD and may help explain the missing link between OA circulation and systemic arterial compliance.

Correlation among choroidal, parapapillary, and retrobulbar vascular parameters in glaucoma

PURPOSE

To study and compare the correlation among choroidal, parapapillary, and retrobulbar vascular parameters in healthy subjects, glaucoma suspects, and open-angle glaucoma (OAG) patients.

DESIGN

Prospective observational clinical study.

METHODS

The study included one randomly selected eye from 21 normal subjects, 30 glaucoma suspects based on optic disc appearance, and 22 OAG patients. The pulsatile ocular blood flow (POBF), a measure of choroidal blood flow, was assessed using ocular blood flow analyzer whereas parapapillary blood flow and blood velocity of retrobulbar blood vessels were measured using scanning laser Doppler flowmetry and color Doppler imaging, respectively. All vascular parameters along with blood pressure and intraocular pressure measurements were obtained within a 2-hour period. Univariate regression analyses were used to evaluate the correlation of POBF values with parapapillary blood flow values, retrobulbar blood flow velocities, and resistive index, which represents vascular resistance, in each group. Two multiple linear regression models were created based on results of univariate analyses and included POBF, mean parapapillary blood flow, age, and mean ocular perfusion pressure; and POBF, temporal short posterior ciliary artery resistive index, age, and mean ocular perfusion pressure.

RESULTS

POBF was significantly associated with parapapillary blood flow (r2 = 0.54; P < .001, positive correlation) and temporal short posterior ciliary artery resistive index (r2 = 0.39; P < .001, negative correlation) in normal subjects. Results were consistent when corrected for age, intraocular pressure, and blood pressure parameters. POBF values did not correlate with parapapillary blood flow values or temporal short posterior ciliary artery resistive index in glaucoma suspects or OAG patients.

CONCLUSION

The relationships of POBF with parapapillary blood flow and calculated retrobulbar vascular resistance differs among normal subjects, glaucoma suspects, and OAG patients. This provides further evidence of vascular dysregulation in OAG.

Perimetric and retrobulbar blood flow changes following carotid endarterectomy

BACKGROUND

Carotid stenosis can produce visual changes. This study examines perimetric and retrobulbar blood flow changes following carotid endarterectomy (CEA) in patients without visual symptoms.

METHODS

Sixteen patients (13 male, three female) with bilateral carotid stenosis were included. Patients with a history of ophthalmic disease, including glaucoma, were excluded. Peak systolic velocity (PSV) in the ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (SPCAs) was measured preoperatively and 12 months following CEA with color Doppler imaging (CDI), using a 7.5 MHz probe, at both the side operated upon and its fellow side. Automated static perimetry (Octopus 500 perimeter, G1x program) was performed at the same intervals. Mean sensitivity (MS), mean defect (MD), loss variance (LV) and corrected loss variance (CLV) were recorded.

RESULTS

Preoperative PSV in the OA was significantly lower in the side operated on. Preoperative perimetric parameters were significantly compromised, compared with normative data, in both eyes. Postoperatively, PSV had significantly improved in all vessels examined in the carotid that was operated on, but only in the OA and SPCAs in the fellow side. MD had significantly improved postoperatively for both eyes, whereas improvement in the other perimetric parameters examined was not statistically significant.

CONCLUSIONS

Perimetric changes occur in carotid stenosis. CEA results in the improvement of retrobulbar blood flow and perimetric parameters. Further research will be required to determine whether perimetric parameters may be used as additional indicators for carotid endarterectomy.

Evaluation of ocular surface temperature and retrobulbar haemodynamics by infrared thermography and colour Doppler imaging in patients with glaucoma

BACKGROUND

Ocular surface temperature (OST) could berelated to retrobulbar haemodynamics in patients with glaucoma.

AIMS

To compare OST measurements in patients with glaucoma and healthy controls, and to investigate the correlation between OST, intraocular pressure (IOP) and retrobulbar haemodynamics in patients with glaucoma.

METHODS

32 patients with primary open-angle glaucoma (POAG) and 40 controls were included in the study. The parameters considered both in patients with POAG and in controls were IOP and OST values measured by infrared ocular thermography. Colour Doppler imaging was used to determine haemodynamic parameters in ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCAs) in patients with POAG.

RESULTS

OST values were significantly lower in patients with POAG than in controls (p<0.001). OST was negatively related with resistivity index of OA (p<0.001), CRA (p = 0.001) and SPCAs (p<0.001), and positively related with end-diastolic velocity of OA (p = 0.02) and SPCAs (p = 0.05).

CONCLUSION

This study suggested that OST could be a marker of impaired retrobulbar haemodynamics in patients with glaucoma.

Hemodynamic evaluation of the posterior ciliary circulation in exfoliation syndrome and exfoliation glaucoma

BACKGROUND

Previous studies have reported impaired blood flow in the ophthalmic artery (OA) and central retinal artery (CRA) in exfoliation syndrome and exfoliation glaucoma. This study evaluates blood flow at the long and short posterior ciliary arteries (LPCA and SPCA, respectively) in these conditions.

METHODS

Consecutively examined candidates for cataract surgery were included. Only one eye (OD) was included in the analyses for consistency. Patients were classified into non-glaucoma and non-exfoliation (controls), primary open angle glaucoma (POAG), exfoliation syndrome and exfoliation glaucoma groups, based on the findings of the OD. Sixty-eight patients (41 males, 60.3%) were included. Color Doppler imaging (CDI) of the nasal and temporal branches of LPCA and SPCA was performed using a 7.5 Mhz probe. The peak systolic velocity (PSV), end diastolic velocity (EDV) and resistivity index (RI) were recorded for the examined vessels.

RESULTS

EDV at the LPCA was significantly lower in exfoliation syndrome and glaucoma, compared with controls and POAG respectively. EDV was significantly lower and RI was significantly higher at the SPCA in exfoliation glaucoma, compared with exfoliation, whereas respective differences were statistically not significant between controls and POAG.

CONCLUSIONS

The hemodynamic impairment at the LPCA in exfoliation syndrome and glaucoma supports an association between exfoliation and ischemic stress at the anterior ocular segment.

Compromised Autoregulatory Control of Ocular Hemodynamics in Glaucoma Patients after Postural Change

PURPOSE

The autoregulatory control of retrobulbar blood flow in response to postural challenge was investigated in normal-tension glaucoma (NTG) patients in comparison with primary open-angle glaucoma (POAG) patients and healthy volunteers.

DESIGN

Prospective cohort study.

PARTICIPANTS AND CONTROLS

Twenty POAG patients, 20 NTG patients, and 20 control subjects.

METHODS

Peak systolic velocity (PSV), end diastolic velocity (EDV), and resistivity index (RI) in the short posterior ciliary artery (SPCA), central retinal artery (CRA) and ophthalmic artery (OA) were recorded after a change from sitting upright to a supine body position using color Doppler imaging.

MAIN OUTCOME MEASURES

Peak systolic velocity, EDV, and RI.

RESULTS

Ten minutes after postural change to a supine position, blood flow velocities in the SPCA remained unchanged in controls, whereas a significant increase of PSV and EDV was found in both glaucoma groups. The RI in the SPCA was significantly lowered in the NTG group. Recordings for the OA and CRA showed a significant increase in EDV and significant decrease in RI in all 3 groups; a significant increase in PSV in the CRA was detected only in the NTG group.

CONCLUSIONS

The unaltered flow velocities in the SPCA of healthy controls may indicate tight autoregulatory control, whereas the flow velocities in the CRA and OA appeared to follow alterations in hydrostatic pressure. In contrast, NTG and POAG patients demonstrated an insufficient compensatory response to postural change, leading to accelerated flow in the SPCA. This compromised autoregulatory control could represent another contributing factor in the pathogenesis of glaucoma.

Retrobulbar blood flow in patients with cataract

OBJECTIVE

To investigate retrobulbar haemodynamics in patients with cataract.

SUBJECTS AND METHODS

Colour Doppler imaging of the ophthalmic artery was carried out on the eye scheduled for surgery in 30 patients with cataract and in one randomly selected eye of 100 healthy controls. The peak systolic velocity, mean velocity, end diastolic velocity and resistivity index in the ophthalmic artery were computed and adjusted for the influence of age and mean arterial pressure. Cataract type was recorded and lens opacity was measured with an opacity lensmeter. Odds ratio (OR) for cataract was analysed in a logistic regression model, depending on the adjusted blood-flow parameters, age and smoking status.

RESULTS

The mean (SD) age was 45.5 (17.7) and 67.6 (5.8) years in controls and patients with cataract, respectively (p<0.001). The female to male ratio was 54:46 and 13:17, respectively (p = 0.41). Significant predictors of cataract in a forward stepwise logistic regression analysis were age (OR = 1.194; 95% confidence interval (CI) = 1.103 to 1.292; p<0.001), smoking status (OR = 14.119; 95% CI = 2.753 to 72.398; p = 0.002) and mean blood-flow velocity in the ophthalmic artery (OR = 0.731; 95% CI = 0.607 to 0.881; p = 0.001). Adjusted mean velocity was significantly lower in patients with cataract, even when only age-matched (age >55 years) non-smokers (31 controls, 19 patients with cataract) were considered (p = 0.003). Lens opacity and the type of cataract had no influence on the present findings.

CONCLUSION

High mean velocity in the ophthalmic artery may be associated with a reduced risk of cataract.

Glaucoma progression is associated with decreased blood flow velocities in the short posterior ciliary artery

BACKGROUND

An altered perfusion of the optic nerve head has been proposed as a pathogenic factor in glaucoma.

AIM

To investigate potential differences in the ocular haemodynamics of patients having glaucoma with progressive versus stable disease, as well as healthy volunteers.

METHODS

Peak-systolic velocity (PSV), end-diastolic velocity (EDV) and resistivity index in the short posterior ciliary artery (SPCA), central retinal artery (CRA) and ophthalmic artery were recorded in 114 consecutive patients having glaucoma with an intraocular pressure (IOP) < or =21 mm Hg, as well as in 40 healthy volunteers, by colour Doppler imaging (CDI).

RESULTS

Of the 114 patients with glaucoma, 12 showed glaucoma progression (follow-up period: mean 295 (standard deviation (SD) (18) days). CDI measurements in these patients showed decreased PSV and EDV in the SPCA (p<0.001 and p<0.05, respectively) and decreased PSV in the CRA compared with patients with stable glaucoma and healthy controls (p<0.05). No differences in flow velocities were found for the ophthalmic artery. IOP and systemic blood pressure was similar in all the three groups.

CONCLUSIONS

Progressive glaucoma is associated with decreased blood flow velocities in the small retrobulbar vessels supplying the optic nerve head. The detected difference could represent a risk factor for progression of glaucomatous optic neuropathy.

Normal reference intervals and ranges of side-to-side and day-to-day variability of ocular blood flow Doppler parameters

The study presents normal reference intervals and ranges of "normal" side-to-side and day-to-day variability of ocular blood flow Doppler parameters. Peak-systolic (PSV), end-diastolic velocity (EDV) and impedance indices in the ophthalmic artery (OA), the central retinal artery (CRA) and the short posterior ciliary artery (SPCA) of both orbits were determined with color-coded duplex sonography in 140 healthy volunteers (range 18 to 83 y; 68 men and 72 women). Decreases in flow velocities and concomitant increases in impedance indices were found in all arteries with advancing age. The PSV and the EDV values for the OA, the CRA and the SPCA in the age group less than 40 yr-old were 40.6 +/- 8.9 and 11.2 +/- 3.7, 9.9 +/- 1.8 and 3.7 +/- 0.9, 13.8 +/- 2.6 and 5.7 +/- 1.5 cm/s (mean +/- SD), respectively. In the 40 to 60 yr-old age group, the values were 35 +/- 7.9 and 10.7 +/- 4.3, 9.7 +/- 2 and 3.5 +/- 0.8, 13.5 +/- 2.9 and 5.3 +/- 1.5 cm/s. In the age group over 60 yr-old, the values were 34 +/- 8 and 8.4 +/- 3.3, 9.3 +/- 2 and 3 +/- 0.9, 12.8 +/- 2.4 and 4.3 +/- 1.2 cm/s. In the youngest age group, the EDV in the CRA and the SPCA was higher in women, while in the OA the PSV and the EDV were higher in men. Ranges of side-to-side variability in the OA, the CRA and the SPCA, determined with repeatability coefficient for the PSV and the EDV, were 24, 5.4, 7.5 cm/s and 11, 2.5, 4.2 cm/s, respectively, whereas the values for day-to-day variability were 16.8, 4.3, 6.7 cm/s and 5.6, 1.7 and 3.9 cm/s. Ocular blood flow Doppler parameters range widely and are significantly age and sex dependent. Ranges of "normal" side-to-side and day-to-day variability of the parameters can help to determine abnormal flow pattern.

Volumetric colour Doppler imaging: a useful tool for the determination of ocular blood flow in glaucoma patients?

PURPOSE

Disturbed ocular haemodynamics are discussed to contribute to the pathogenesis of glaucoma. Up to now there is no method available allowing direct determination of blood flow, which is the most relevant dimension for studies on haemodynamics. In this study, volumetric colour Doppler imaging (vCDI) is evaluated systematically in glaucoma patients.

METHODS

A Siemens Elegra ultrasound set-up with a linear 7.5 MHz probe was used for all CDI measurements. For vCDI, the cross-sectional area of a vessel and the flow velocity is determined. From both these parameters blood flow can be calculated. Ocular pulse amplitude (OPA) was assessed by the method of Langham using a pneumatic applanation tonometer.

RESULTS

(1) Velocity measurements using CDI in the ophthalmic artery and central retinal artery were highly reproducible (n=20). In contrast, reproducibility of vCDI measurements was low (n=20). Reproducibility improved if five vCDI measures were averaged. (2) Results from two different CDI-operators did not differ regarding the velocity measurements, but there was a difference in vCDI measurements (n=20). (3) Results from vCDI did not correlate with measurements of OPA in 69 patients. (4) In 15 patients, vCDI failed to detect changes of ocular perfusion induced by the application of dorzolamide.

CONCLUSION

vCDI is not applicable in ophthalmology at present.

Effects of glaucoma drugs on ocular hemodynamics in normal tension glaucoma: a randomized trial comparing bimatoprost and latanoprost with dorzolamide [ISRCTN18873428]

Background

Reduced choroidal perfusion is hypothesized to play a role in the pathogenesis of normal tension glaucoma. Thus the impact of antiglaucomatous eye drops on ocular perfusion has been the focus of recent research and the subject of intensive investigations. The present study investigates whether topically applied latanoprost or bimatoprost influence ocular perfusion in patients with normal tension glaucoma and compares these effects with that changes detected after the treatment with dorzolamide.

Methods

Ocular hemodynamics were assessed by color Doppler imaging (CDI) shortly before and after a one-month treatment with either latanoprost, bimatoprost or dorzolamide. Primary end-points of the study were peak systolic and end-diastolic blood flow velocities in the short posterior ciliary artery (SPCA) under the new therapy. Intraocular pressure (IOP) and additional perfusion parameters in the SPCA and other retrobulbar vessels were tracked as observational parameters. n = 42 patients with normal tension glaucoma were enrolled in the study.

Results

Systolic and diastolic blood flow velocities in the SPCA showed no significant alteration after the treatment with latanoprost or bimatoprost. Dorzolamide lead to increase of peak systolic velocity. IOP was reduced by all three agents in a range reported in the literature.

Conclusion

Topically applied latanoprost and bimatoprost act in a hemodynamically neutral manner and have the capability to lower IOP even in patients with normal tension glaucoma and low initial IOP level. Dorzolamide accelerates blood flow in systole. None of the tested compounds has a negative impact on hemodynamics in the short posterior ciliary arteries.

Blood flow in glaucoma

PURPOSE OF REVIEW

Glaucoma, one of the leading causes of blindness in the world, is characterized by progressive visual field loss and distinctive excavation of the optic nerve head. Although elevated intraocular pressure is the major risk factor, there is increasing evidence that the pathogenesis of glaucoma is also linked to altered ocular blood flow. This review summarizes the recent publications relevant to blood flow in glaucoma.

RECENT FINDINGS

Several studies indicate that a perfusion instability, rather than a steady reduction of ocular blood flow, might contribute to glaucomatous optic neuropathy. The main cause of the instability is a disturbed autoregulation in the context of a general vascular dysregulation. The underlying mechanism of such a vascular dysregulation is not known. A dysfunction of both the autonomic nervous system and vascular endothelial cells is discussed.

SUMMARY

The mechanical and vascular theories are not mutually exclusive; on the contrary, a vascular dysregulation increases the susceptibility to intraocular pressure. Therapeutically, therefore, both an intraocular pressure reduction and an improvement of the ocular blood flow might be considered.