Orbital Blood Flow Research Articles

Relationship between the effect of carbon dioxide inhalation or nilvadipine on orbital blood flow in normal-tension glaucoma.

To investigate the relationship between the effect of carbon dioxide (CO2) inhalation or oral nilvadipine, a calcium-channel blocker, on orbital blood flow in patients with normal-tension glaucoma, as determined by color Doppler imaging. Sixteen patients with normal-tension glaucoma (mean age, 55.6+/-9.8 years; male:female ratio, 3:13) underwent color Doppler imaging to measure the resistance index, and peak systolic and end-diastolic blood flow velocities of the ophthalmic artery, central retinal artery, and nasal and temporal short posterior ciliary arteries. Measurements were taken before and during CO2 supplementation sufficient to increase the end-tidal CO2 partial pressure by 10%. The color Doppler imaging measurements were repeated after 2 to 4 weeks of treatment with 2 mg oral nilvadipine, and comparisons were made between the effects of the two treatments. Both CO2 inhalation and nilvadipine treatment significantly reduced the resistance index in the central retinal artery, nasal short posterior ciliary artery, and temporal short posterior ciliary artery. There was a significant correlation between the effects of the two treatments on the difference in the resistance indexes of the ophthalmic artery and central retinal artery, but not on those of the nasal or temporal short posterior ciliary artery. Both CO2 inhalation and oral nilvadipine significantly reduce the resistance index measured by color Doppler imaging in orbital vessels. The effect of oral nilvadipine might be predicted by CO2 inhalation in patients with normal-tension glaucoma.

Color Doppler Imaging of Ocular Blood Flow after Topical Ketanserin

The authors investigated the effect of ketanserin 0.5% eye drops on intraocular pressure and orbital blood flow in some healthy volunteers. Ketanserin is a selective antagonist of serotonin S₂ receptors; moreover, it produces an α₁-blocking effect. It causes a systemic reduction of blood pressure and capillary vasodilatation. Three hours after topical administration of ketanserin 0.5%, the intraocular pressure was decreased by about 14% from the baseline. At the same time, we observed by color Doppler imaging that the mean percent increase in the peak systolic velocity in the ophthalmic artery (OA) was 5.18% (p < 0.161) and 23.18% (p < 0.001) in the posterior ciliary arteries (PCAs). The mean resistance index of the OA was in contrast reduced by 1.16% (p < 0.669) and by 32.14% (p < 0.003) in the PCAs. These data show that ketanserin 0.5% eye drops may be useful not only to decrease intraocular pressure but also to improve blood flow in the PCAs that supply the optic nerve head.

A New System to Supply Carbon Dioxide Safely to Glaucoma Patients

Purpose: To develop a new system for safely supplying carbon dioxide (CO 2) to open-angle glaucoma patients. Methods: The orbital hemodynamics of 7 glaucoma patients were determined by color Doppler imaging under baseline conditions and during CO 2 supplementation sufficient to increase the end-tidal CO 2 partial pressure by 10%. Systemic conditions, including oxygen saturation and blood pressure, were monitored throughout the CO 2 inhalation. Results: Our results demonstrate that this new system enables us to supply CO 2 in a safe, controlled manner to glaucoma patients. Conclusions: This new system will be useful for investigating the effects of vasodilation by CO 2 on orbital blood flow.

Ocular Hypertension and Primary Open-Angle Glaucoma

To compare the orbital blood flow velocities of patients with long-standing ocular hypertension and patients with primary open-angle glaucoma. Twenty patients with ocular hypertension were recruited from our clinic and underwent color Doppler imaging evaluation of their retrobulbar vessels. The blood flow velocities and resistance index of their central retinal artery, temporal short posterior ciliary artery, and ophthalmic artery were compared with those of 20 glaucoma patients individually matched for age and level of the highest untreated intraocular pressure ever recorded. Glaucoma patients had significantly lower peak systolic velocity and end-diastolic velocity than did patients with ocular hypertension in their central retinal artery (p < 0.001). No significant difference between the groups was observed in the other vessels studied. Glaucoma patients had lower blood flow velocity in the central retinal artery compared with that of ocular hypertension patients of similar age and level of untreated intraocular pressure. This might be important in the development of glaucomatous damage in those patients.

Unilateral Open-Angle Glaucoma Secondary to Idiopathic Dilated Episcleral Veins

To determine the cause of unilateral dilated tortuous episcleral vessels in a 34-year-old patient. The patient underwent slit-lamp examination, visual field testing, tonographic measurement, orbital ultrasound examination, orbital color Doppler blood flow measurement, dye-enhanced computed topographic scan, and selective carotid angiography. Disk cupping and early scotoma were present. Gonioscopy showed Schlemm's canal engorged with blood. The only pathologic findings were an increased tonographic resistance to outflow and increased arterial and venous episcleral flow on color-coded Doppler sonography. The origin of this episcleral vessel abnormality is still unknown.

Color Doppler Hemodynamics of Giant Cell Arteritis

Objectives: To determine quantitative and qualitative hemodynamic alterations within the ophthalmic, central retinal, and short posterior ciliary arteries in patients with giant cell arteritis (GCA) proved by biopsy specimen. Design, Patients, and Setting: A consecutive case series of patients with GCA referred to an urban eye hospital who were evaluated with color Doppler imaging that was used to analyze orbital blood flow velocities and vascular resistance in 22 consecutive patients with GCA compared with age and sex-matched controls. Results: Patients with GCA all demonstrated significantly reduced central retinal and short posterior ciliary arterial mean flow velocities as well as significantly increased vascular resistance compared with matched controls. Ophthalmic artery mean flow velocity demonstrated marked variation depending on the anatomic location studied. Other color Doppler imaging characteristics of GCA included the following: ophthalmic artery aliasing (high velocity and turbulent flow at presumed focal vasculitic stenoses), reversal of flow within the ophthalmic artery, reduced and truncated timevelocity waveforms of the central retinal and short posterior ciliary arteries, and absolute deficits of flow within the central retinal and short posterior ciliary arteries. Aliasing of flow velocity within the ophthalmic artery (two patients) was associated with clinical progression of GCA. Conclusions: These data support the concept that quantitative and qualitative alterations in blood flow are pathophysiologic mechanisms of visual loss in GCA. This technique may be useful in the diagnosis and management of GCA since some of the color Doppler waveforms observed in GCA have not been seen in nonarteritic optic neuropathy. Treatment with corticosteroids often appears to stop the progression of these hemodynamic abnormalities but generally does not improve preexisting vascular abnormalities.

Color Doppler Imaging of Normal Orbital Vasculature

Color Doppler imaging has become a useful adjunctive tool in diagnosing ophthalmic vascular disease. However, a paucity of information exists regarding normal values. This investigation was conducted to generate a database of normal retrobulbar circulatory parameters. The authors prospectively studied the retrobulbar hemodynamic parameters of 53 normal eyes from 32 healthy individuals of various ages, all without risk factors for the development of systemic vascular disease. Preliminary Doppler spectral analysis was used to demonstrate normal carotid arterial, carotid siphon, and ophthalmic vascular anatomy. Mean hemodynamic values were recorded for each retrobulbar vessel. Diastolic blood pressure significantly correlated with ophthalmic arterial end-diastolic velocity (P < 0.05) and pulsatility index (P < 0.05). Although end-diastolic velocity significantly decreased (P < 0.05) and vascular resistance significantly increased (P < 0.05) as a function of age in the posterior ciliary and central retinal arterial circulation, no such correlation was identified in the ophthalmic artery which demonstrated significantly more hemodynamic variability among individuals (P < 0.00001). No significant differences in blood flow or vascular resistance were noted between sexes, fellow orbits, or the nasal and temporal branches of the posterior ciliary artery within individual orbits. Orbital hemodynamic parameters do not appear to be sex dependent or variable between fellow orbits. These data suggest that age and diastolic blood pressure may affect normal orbital blood flow and vascular resistance patterns. Significant interindividual variability is limited only to ophthalmic arterial blood flow.

Thallium-201 Uptake in the Orbits

Thallium-201 uptake patterns in the orbits are not widely known. Diffuse, bilateral orbital localization of TI-201 chloride may be an incidental finding because of orbital muscle or other soft tissue uptake. Differences in orbital blood flow and soft tissue mass may be the cause of the varying uptake intensities in most cases. Focal uptakes, even when bilateral, may indicate specific pathology and should be investigated. Sample cases are presented.

Color Doppler Hemodynamics of Giant Cell Arteritis

To determine quantitative and qualitative hemodynamic alterations within the ophthalmic, central retinal, and short posterior ciliary arteries in patients with giant cell arteritis (GCA) proved by biopsy specimen. A consecutive case series of patients with GCA referred to an urban eye hospital who were evaluated with color Doppler imaging that was used to analyze orbital blood flow velocities and vascular resistance in 22 consecutive patients with GCA compared with age and sex-matched controls. Patients with GCA all demonstrated significantly reduced central retinal and short posterior ciliary arterial mean flow velocities as well as significantly increased vascular resistance compared with matched controls. Ophthalmic artery mean flow velocity demonstrated marked variation depending on the anatomic location studied. Other color Doppler imaging characteristics of GCA included the following: ophthalmic artery aliasing (high velocity and turbulent flow at presumed focal vasculitic stenoses), reversal of flow within the ophthalmic artery, reduced and truncated time-velocity waveforms of the central retinal and short posterior ciliary arteries, and absolute deficits of flow within the central retinal and short posterior ciliary arteries. Aliasing of flow velocity within the ophthalmic artery (two patients) was associated with clinical progression of GCA. These data support the concept that quantitative and qualitative alterations in blood flow or pathophysiologic mechanisms of visual loss in GCA. This technique may be useful in the diagnosis and management of GCA since some of the color Doppler waveforms observed in GCA have not been seen in non-arteritic optic neuropathy. Treatment with corticosteroids often appears to stop the progression of these hemodynamic abnormalities but generally does not improve preexisting vascular abnormalities.

Orbital colour Doppler imaging.

Colour Doppler imaging (CDI) is an ultrasonic method for qualitatively and quantitatively assessing blood flow. Recently this technique has been adapted for investigation of the orbital, optic nerve and ocular vasculature. We discuss the history, principles and methodology of this examination technique for ophthalmology. Also described are normal haemodynamic characteristics as well as the findings in common pathological states involving derangements of orbital blood flow. Although CDI is relatively new to ophthalmology it has already proved to be of benefit in conditions with altered orbital, ocular and optic nerve blood flow. In the future it is expected that the indications for the applications of CDI will become more clearly defined and that orbital CDI will be more widely available and utilised, especially in the investigation of vascular diseases of the orbit, optic nerve and retina.

Increased orbital frontal cortex blood flow and hippocampal abnormality in PTSD: A pilot pet study : William E. Semple, Peter Goyer, Richard McCormick, Evan Morris, Beth Compton, Beverly Donovan, Mark Berridge, Floro Miraldi, S. Charles Schulz Case Western Reserve Medical School, University Hospitals, Cleveland, OH 44106

Increased orbital frontal cortex blood flow and hippocampal abnormality in PTSD: A pilot pet study : William E. Semple, Peter Goyer, Richard McCormick, Evan Morris, Beth Compton, Beverly Donovan, Mark Berridge, Floro Miraldi, S. Charles Schulz Case Western Reserve Medical School, University Hospitals, Cleveland, OH 44106

Color Doppler Imaging Provides Accurate Assessment of Orbital Blood Flow in Occlusive Carotid Artery Disease

Color Doppler imaging was used to evaluate the hemodynamics of the ophthalmic vasculature in a case of complete internal carotid artery occlusion. This procedure, which allows rapid, noninvasive imaging, showed a partial ophthalmic artery obstruction with absent flow in the central retinal artery, central retinal vein, and nasal posterior ciliary arteries. Although altered perfusion of the retinal vessels may be evaluated clinically, assessment of blood flow in the ophthalmic and ciliary arteries previously could be evaluated only indirectly by intravenous fluorescein angiography. The color Doppler imaging findings were confirmed by intravenous fluorescein angiography and carotid arteriography. Color Doppler imaging represents a noninvasive method to diagnose abnormal blood flow of the ophthalmic artery and its branches and to evaluate serial changes of the circulation in a noninvasive manner.

The pathophysiology of the Anophthalmic socket; Analysis of orbital Blood Flow and Obital Fat

The pathophysiology of the Anophthalmic socket; Analysis of orbital Blood Flow and Obital Fat

The Pathophysiology of the Anophthalmic Socket Part I. Analysis of Orbital Blood Flow

A wide variety of complications of the anophthalmic socket develop in patients after enucleation, including enophthalmos, superior sulcus deformities, eyelid malpositions, implant migration and extrusion, poor prosthetic motility, and socket contraction. Changes in the orbital blood flow and metabolic activity of the socket tissues and atrophy of the orbital fat occurring after enucleation have been suggested as two theoretical mechanisms that result in the development of these clinical conditions. Lack of scientific evidence and a limited understanding of the pathophysiologic basis of the features of anophthalmos led us to evaluate the validity of these proposed mechanisms in an animal model. Selected parameters of the normal orbits were compared with the contralateral anophthalmic orbits at different time intervals after surgery. Orbital blood flow was studied with selective ophthalmic artery angiography and radioactive microsphere techniques. Ophthalmic arteriography demonstrated symmetric caliber and filling characteristics of the major orbital vessels of the control and experimental orbits, although their topographic course was slightly more tortuous in the anophthalmic socket. Results of radioactive microsphere analysis of capillary blood flow per weight of the different orbital tissue compartments of the animals in the long-term group showed no significant difference between the normal and anophthalmic sockets. These findings provide evidence that the circulation dynamics and blood flow to orbital tissues do not change after enucleation surgery.

The Pathophysiology of the Anophthalmic Socket Part II. Analysis of Orbital Fat

The pathophysiologic mechanisms responsible for the clinical features of the anophthalmic socket are poorly understood. Atrophy of orbital fat has been thought to be a major contributing cause of enophthalmos and the superior sulcus deformities that develop after enucleation, but it has never been demonstrated histopathologically or confirmed by scientific analysis. This study was undertaken to investigate the changes that occur in the orbital fat compartment of the anophthalmic socket in an animal model by measuring orbital soft tissue mass and evaluating adipocyte cell size. Instead of reduction in the tissue mass, a statistically significant greater weight of the fat and connective tissue compartment was found in the anophthalmic orbit by nearly 13% compared to the control orbit in the animals in the long-term group. No significant change in the mean maximal diameter of adipocytes developed 7 months after enucleation. These analyses do not support the concept that orbital fat atrophy or a reduction of metabolic activity occurs in the anophthalmic socket in this animal model. From these results and our previous findings that the circulation dynamics and blood flow to orbital tissues do not change after enucleation, we propose that the pathophysiologic basis of the problems associated with anophthalmos is a disturbance in the spatial architecture and interrelationships of the multiple tissue components of the orbit, not a change in the orbital blood flow or development of fat atrophy.

Noninvasive Carotid Evaluation Using Pulsed Doppler Imaging for Patients with Ophthalmic Disorders

Pulsed Doppler imaging provides an accurate, noninvasive technique for evaluation of the carotid bifurcation. We have found it useful in evaluating patients with amaurosis fugax and ocular emboli. It can also be used to evaluate blood flow within ocular and orbital tumors. The continuous wave Doppler is useful for detection of abnormal orbital blood flow in patients with dural-cavernous fistulae.