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PubMed1975

High altitude retinal hemorrhage.

The accessibility of high-altitude areas presents the risk of high altitude retinal hemorrhages (HARH). Four cases reported illustrate localized macular, diffuse, and familial incidence of HARH. Fluorescein angiography indicated no leakage, and a superficial retinal location of the hemorrhages. Marked retinal artery and vein dilation occurs. Ophthalmodynamometry showed retinal vascular hypertension in the presence of HARH. The complete resolution of hemorrhages occurs in most cases. Despite the return of visual acuity to normal, visual function studies indicate the persistance of defects.

Adult↗
PubMed1975

Ophthalmic arterial blood pressures measured by ocular plethysmodynamography.

The indirect measurement of ophthalmic arterial blood pressure is an important index in the understanding of cerebral vacsular hemodynamics. Ophthalmodynamometry (ODM), the prototype for such measurement, is, however, replete with difficulties that have limited its widespread use. A preliminary evaluation of a new technique for ODM identified as ocular plethysmodynamography, has yielded accurate opthalmic blood pressure data without the attendant problems. Reproducible values for bilateral ophthalmic arterial pressure levels have been determined in 30 normal volunteers and the levels correlated to brachial arterial pressure levels. In a series of patients with arteriographically demonstrable carotid obstructive lesions, the preoperative and postoperative ophthalmic arterial blood pressure relationships exhibited excellent correlation with the roentgenographic and intraoperative data.

Adult↗
PubMed1990

A parametric evaluation of retinal vascular perfusion pressure and visual neural function in man.

Body inversion and ophthalmodynamometry were used to alter the intraocular pressure/retinal vascular perfusion pressure (IOP/RVPP) relationship in 10 normotensive adults. Using scotopic and photopic flash electroretinograms (fERGs), a heightened susceptibility of the rod system relative to the cone system was identified for transient alterations of the RVPP. The scotopic fERG b-wave decreased by about 40% and the photopic fERG was relatively unchanged when the RVPP was reduced by 51%. When the RVPP was increased by some 90%, the scotopic b-wave decreased by about 11%, and the photopic fERG by 8%. The greater vulnerability of the rod system than the cone system to decreased RVPP was tentatively attributed to structural differences between the photoreceptor types, their retinal distribution, and the effectiveness of vascular autoregulatory mechanisms. The neural generators of the pattern evoked retinal potential (pERG) showed a large impairment in function with both an increase and a decrease in the RVPP. In contrast, pattern evoked cortical potentials (pVEPs) showed a significant reduction in amplitude only when the RVPP was increased. These latter results suggest that the generators of pERGs are dependent on some ideal and narrow range of RVPP for normal activity whereas the generators of pVEPs are more vulnerable to the direct pressure effects of vascular engorgement within the eye and intracranial structures.

Adult↗
PubMed1984

Reversed ophthalmic Doppler signal: a study of its significance.

The pathophysiological significance in carotid artery stenoses of a collateral circulation via the external carotid and ophthalmic arteries is investigated with the use of three non-invasive techniques: Doppler ultrasonography, ophthalmodynamometry and ophthalmodynamography . 21 Carotid arteries with and 26 without a stenosis greater than 50% at angiography are studied. Finding a reversed flow direction in the ophthalmic artery points towards a low pressure in the carotid syphon and indicates that the patient is, hemodynamically speaking, in danger. This concerns the cerebral as well as the retinal circulation.

Arterial Occlusive Diseases↗
PubMed1983

Differential diagnosis of central retinal vein obstruction.

When obstruction of the central retinal vein presents in its florid hemorrhagic form, with disc edema and myriad, widespread retinal hemorrhages, there can be little doubt as to the proper diagnosis. However, when obstruction is incomplete, there may be confusion as to terminology, etiology, and proper treatment. "Venous-stasis retinopathy" was the term used in the early 1960s to describe the ophthalmoscopic changes recognized as resulting from the chronic ischemic changes induced by severe occlusive disease of the carotid artery. In the late 1970s, others began to use the term "venous-stasis retinopathy" to describe the incomplete or nonflorid type of central vein obstruction. These two conditions, although similar in appearance, have differences that allow their differentiation. The main differentiating feature is that the retinal artery pressure, as measured by ophthalmodynamometry or oculopneumoplethysmography, is always low in the retinopathy of carotid occlusive disease. These two conditions must be differentiated in order to manage the retinopathy properly as well as to recognize the potential for neurologic catastrophe.

Aged↗
PubMed1985

Clinical applications of noninvasive carotid artery testing.

The management of patients with cerebral transient ischemic attacks and carotid artery stenosis remains controversial. Noninvasive techniques help to determine which patients require surgical intervention without exposing the majority of patients to the risk and discomfort of invasive procedures. Measurement of ophthalmic artery pressure by ophthalmodynamometry or oculoplethysmography gives a representation of perfusion pressure in the internal carotid artery circulation. Doppler ultrasound studies can define the extent of obstruction to flow at the carotid artery bifurcation and assess collateral flow from the external carotid artery. Real time B-mode ultrasonography can detect nonobstructive ulcerated plaque in the carotid artery bifurcation. Employing these examinations in a test battery can identify hemodynamically significant lesions, which are more likely to precipitate a stroke. The information obtained from these studies can be utilized in patients with episodes of cerebral transient ischemic attacks, asymptomatic carotid artery bruits and vertebrobasilar insufficiency. Noninvasive carotid artery testing is also useful in screening patients with nonspecific symptoms, such as dizziness or light-headedness, which may be related to decreased flow in the carotid circulation. Noninvasive carotid artery testing can provide valuable anatomic and physiologic information required in the appropriate management of patients with cerebrovascular disease. It is of particular value in managing patients with heart disease who are at high risk for complications from invasive procedures.

Arteriosclerosis↗
PubMed2004

[Non-invasive determination of intracranial pressure. Physiological basis and practical procedure].

It has been shown in some recently published papers that the intracranial pressure can be determined by dynamometric measurement of the outflow pressure of the central retinal vein (VOP). The knowledge gained by the basic experiments of Baurmann in 1925 has been forgotten by the ophthalmic community for many years. In this paper the basic phenomena of venous collapse are outlined which are fundamentally different from the biomechanics of the arterial collapse phenomenon observed by ophthalmodynamometry. A practical guideline is given for the dynamometric measurement of venous outflow pressure which equals the intracranial pressure. Performing dynamometry of the central retinal vein enables the ophthalmologist to determine intracranial pressure in a non-invasive way.

Humans↗
PubMed1988

[Ulrich and Ulrich oculo-oscillodynamography: results in patients with healthy eyes].

Ulrich and Ulrich's method of oculo-oscillodynamography (OODG) is a relatively new method which enables the systolic retinal, systolic ciliary, and systolic ocular perfusion pressure or respectively blood pressure to be measured. The results obtained by the present authors are in good agreement with those of Ulrich and Ulrich (n = 30). The intraocular pressure values obtained with this method correlate somewhat less well with the systemic blood pressure than is the case with suction cup ophthalmodynamometry. However, the correlation coefficients are sufficiently high to permit their application in ophthalmological diagnosis. The results presented here indicate that the diastolic ocular pressure should be determined by applying the formoscillatory criterion. The positive intercept in the regression equations can be explained by the assumption that the regression is curvilinear at systemic blood pressure values which are generally not encountered in humans in whom OODG is of diagnostic importance. It is suggested that the linear regression is a sufficiently exact model at the systemic blood pressures most frequently measured. Normal OODG values can be read off easily from the diagrams published here.

Adult↗
PubMed1985

[Ulrich oculo-oscillodynamography: initial results in carotid stenoses].

Oculo-oscillodynamography (OODG) after Ulrich was performed in 11 patients suffering from a monolateral, hemodynamically relevant carotid stenosis identified by Doppler sonography. All of the pressure parameters which can be measured by OODG--systolic retinal, systolic ciliary, and diastolic ocular perfusion pressure--were low on the side concerned. In contrast to the already-established methods of measuring ocular perfusion--ophthalmodynamometry and ophthalmodynamography after Hager--the advantages of OODG are that it not only enables the systolic retinal pressure to be differentiated from the systolic ciliary or diastolic ocular perfusion pressure, but also permits the results of the investigation to be illustrated graphically, so that objective evaluation is possible.

Aged↗
PubMed1980

[Measurement of ophthalmic blood pressure with the Mikuni dynamometer (author's transl)].

Comparative measurements of the ophthalmic arterial blood pressure (Mikuni ophthalmodynamometer) and the systemic blood pressure (Riva-Rocci sphygmomanometer) were carried out in 141 eyes of healthy subjects. There was a linear correlation between the two parameters (p < 0.001). The mean diastolic ophthalmic blood pressure was 58.6 mmHg, the mean systolic blood pressure of 93.4 mmHg. The mean diastolic brachial arterial pressure was 86.7 mmHg, the mean systolic pressure 136 mmHg. In all eyes studied the ophthalmic blood pressure was lower than the ipsilateral brachial blood pressure, in respect of the diastolic as well as of the systolic pressure. On the average the ophthalmic blood pressure was 70% of the systemic blood pressure (mean difference 33.6 mmHg). There was no statistically different regression line between the two parameters in subjects with normal and subjects with elevated systemic blood pressure. In 86% of the paired measurements with the Mikuni ophthalmodynamometer there were differences of less than 5 mmHg in systolic pressure (mean 2.64 mmHg). Correspondingly all differences in diastolic pressure in paired measurements were within 5 mmHg (mean 1.46 mmHg). A difference of 7 mmHg in ophthalmic arterial pressures in an individual appears to be probably pathologic; a difference of more than 9 mmHg seems to be definitely pathologic. In ophthalmodynamometry using the Mikuni instrument a "tonographic effect" occurs, and the intraocular pressure takes 10-15 minutes to return to a physiologically stable state. The extent of this tonographic effect depends on the IOP prior to dynamometry. (p < 0,05).

Adolescent↗
PubMed1992

Improving the diagnostic power of electroretinography by transient alteration of the ocular perfusion pressure.

In this report we present the results of a series of studies focusing on the effects of transient changes in the ocular perfusion pressure (OPP) on retinal function in normals as assessed by the flash electroretinogram (ERG). A transient increase or decrease in the OPP affected by body inversion and compression/suction ophthalmodynamometry (ODM), respectively, is shown to affect differentially the b-wave of scotopic and photopic ERG's. However, under dark-adapted conditions, the cone component of the red flash ERG b-wave exhibited a vulnerability to decreased OPP which approached that seen for the b-wave of the scotopic blue flash ERG b-wave. Similar test procedures used to investigate the functional response of the inner plexiform layer during altered OPP revealed component-specific changes in white flash scotopic oscillatory potentials (OP's). The results of these provocative tests of retinal function offer new insights into basic retinal physiology and encouraging prospects for practical clinical diagnostic procedures with enhanced sensitivity and specificity for subclinical retinal disorders.

Dark Adaptation↗
PubMed1996

Acute IOP elevation with scleral suction: effects on retrobulbar haemodynamics.

AIMS/BACKGROUND: Mechanical and vascular factors may both contribute to glaucoma. This study investigated the relation of mechanical to vascular factors by examining how acute IOP elevation altered flow velocities in the central retinal and ophthalmic arteries. METHODS: IOP was elevated from a baseline near 14 to approximately 45 mm Hg using suction ophthalmodynamometry. During recovery from scleral suction, IOP fell to near 8 mm Hg. At each IOP, peak systolic and end diastolic velocities (PSV and EDV) were measured in the central retinal and ophthalmic arteries using colour Doppler imaging (Siemens Quantum 2000). Eleven healthy people served as subjects. RESULTS: Acute elevation in IOP had no effect upon PSV, EDV, or the derived resistance index in the ophthalmic artery: flow velocities in this vessel were identical at IOP of 8 mm Hg or 45 mm Hg. In contrast, in the central retinal artery, PSV and EDV fell, and the resistance index rose, in steady progression as IOP was acutely elevated (each p < 0.01). At IOP of 45 mm Hg, EDV was virtually absent and the resistance index was very nearly 1.0. CONCLUSION: Ophthalmic arterial haemodynamics are unrelated to acute fluctuations of the IOP over a wide range, suggesting that ocular hypertension itself cannot induce vascular dysfunction in this artery. In contrast, flow velocities in the central retinal artery were highly IOP dependent, implying that haemodynamic and mechanical factors are closely linked in this vascular bed.

Acute Disease↗
PubMed1993

Color Doppler imaging of orbital arteries for detection of carotid occlusive disease.

BACKGROUND AND PURPOSE: Distal to a hemodynamically significant stenosis, the Doppler effect becomes dampened. Thus, measuring the flow profile in the ophthalmic artery and the central retinal artery with color Doppler imaging may provide hemodynamic information about the carotid circulation. METHODS: To validate the flow profile measurement with color Doppler imaging in the ophthalmic and central retinal arteries and to determine the sensitivity and specificity of this examination in the detection of hemodynamically significant carotid stenosis, we compared color Doppler imaging examinations with ocular pneumoplethysmography and ophthalmodynamometry examinations in 66 patients with atherothrombotic ischemic cerebrovascular disease. The degree of carotid stenosis in these patients was determined by a duplex scan with color Doppler imaging, and 57 patients underwent angiography to verify the stenosis. RESULTS: The flow velocities (systolic peak velocity and end-diastolic velocity) and pulsatility indices (A/B ratio and resistance index) in the ophthalmic and central retinal arteries decreased as the degree of carotid stenosis increased. There is a statistically significant difference in the mean of systolic peak velocity and the mean of end-diastolic velocity of the ophthalmic and central retinal arteries among groups with various degrees of carotid stenosis (P < .02). Using the flow velocities of the ophthalmic and central retinal arteries to diagnose carotid stenosis (> or = 75% stenosis and occlusion), 8 cm/s for systolic peak velocity in the central retinal artery and 29 cm/s for systolic peak velocity plus flow direction reversal in the ophthalmic artery gave the maximum accuracy (sensitivities, 84% and 85.7% and specificities, 89.6% and 81.7%, respectively). The systolic peak velocity in the central retinal artery varied directly with the systolic pressure of the ophthalmic and central retinal arteries. CONCLUSIONS: The flow velocity and pulsatility in orbital arteries examined by color Doppler imaging provide further hemodynamic information; this test can be used to complement current sonographic examination of carotid disease.

Aged↗
PubMedDate not supplied

Vertebrobasilar insufficiency.

Permanent or transient reduction of the blood flow to the brain is often responsible for dizziness and occasionally sensorineural hearing loss. So far the diagnosis of this condition has been made by angiography, either carotid or vertebral arteriography, but there is a justified reluctance of subjecting unselected patients to this invasive procedure. It is the purpose of this paper to present a new approach to the diagnosis of cerebral vascular insufficiency based on a three-step protocol. The two initial steps are formed by noninvasive techniques and may be used for the selection of those cases requiring additional diagnostic procedures. 1) Cerebral hemodynamic evaluation provides a physiologic assessment of the direct carotid and indirect carotid and vertebral blood flow. It includes ocular plethysmography and ophthalmodynamometry obtained with the patient supine and erect, without and during carotid compression. 2) Computerized tomography allows an evaluation of the brain substance and of the changes produced by vascular insufficiency such as brain atrophy, infarcts and encephalomalacia. A new form of radiographic assessment based on a dynamic evaluation of regional blood flow will be introduced in this paper. 3) Carotid and vertebral arteriograms are performed only on these cases demonstrating a significant cerebral vascular insufficiency by the previous tests and in cases where corrective surgery is contemplated.

Aged↗
PubMed1975

Ocular aspects of internal carotid stenosis.

Because extracranial atheromatous disease of the carotid arterial system is a common cause of 'stroke', ophthalmologists may be the first to see patients at risk who present with early signs of this condition. I. The history of previous observations of these signs and the anatomy and physiology of the structures involved are described. The physical and subjective signs and the significance of transient ischaemic attacks are discussed. Methods of diagnosis are reviewed with special reference to ophthalmodynamometry. II. A series of patients personally investigated and treated is analysed: (1)Endarterectomy was performed in seventy cases of internal carotid artery stenosis during a 15-year period (1959-73). (2) 36 cases from the years 1970-73 were studied in detail. (3) 50 per cent. of these presented with ocular symptoms, which were the only complaint in 22 per cent. (4) 95 per cent. of all patients with ocular symptoms experienced recurrent transient visual loss. (5) 61 per cent. of all patients with ocular symptoms showed significant fundus changes. (6) ODM enabled the haemodynamics of the carotid arterial systems to be evaluated in 79 per cent. of the patients studied. (7) The results of surgery suggest that patients who present with ocular symptoms have a better prognosis than those who present with neurological symptoms only.

Adult↗
PubMedDate not supplied

[The state of circulation in the central artery of the retina and uveal tract in diabetes mellitus].

In 68 diabetic patients a study was made of the state of the circulation in the central artery of the retina and the uveal tract. There was a parallel aggravation of the retinal circulation and of the blood supply in the uveal tract. These disturbances were not infrequently determined before the appearance of ophthalmological changes and were aggravated with increase in the duration and severity of the disease. A wide use of ophthalmodynamometry and rheoophthalmography for the determination of early signs of ophthalmopathy in the patients with diabetes mellitus is recommended.

Adolescent↗
PubMed1978

Detecting extracranial cerebrovascular disease with noninvasive techniques.

Although there are many noninvasive screening tests for extracranial cerebrovascular disease, no single procedure has yet emerged as preeminent. Ophthalmodynamometry is simple but often unreliable. Ocular plethysmography is more complicated and requires moderately expensive equipment. Thermography is often unreliable and also requires costly apparatus. Doppler visualization of the carotid bifurcation is still an experimental tool but looks very promising. Of the currently available techniques, the directional Doppler ophthalmic test has proved most useful in the authors' experience.

Auscultation↗
PubMed1990

[Physiopathology of the cerebral arterial circulation. Application to cerebro arterial surgery].

Autoregulation of cerebral arterial circulation corresponds to a hemodynamic reserve enabling normal cerebral blood flow to be assured when arterial blood pressure drops. However, the capacity of this autoregulatory system is exceeded when pressure drops below 60 +/- 10 mmHg, at which time metabolic disturbances appear followed by the arrest of electric activity and the death or neurons. These ischemic phenomena involve more or less extended regions: cerebral or choroidal arterioles or arteries, or even those of the entire brain. They can occur in series as, for example, the embolism of a cerebral arteriole or artery in a brain already globally hypoperfused downstream from a carotid occlusion or narrow stenosis. The association of these phenomena accounts for the different clinicopathologic cerebrovascular accidents. These disturbances of cerebral blood flow can be explored clinically by isotopic techniques. A cerebral perfusion blood pressure drop can be suspected, when nonhemispheric symptoms appear, on the basis of ophthalmodynamometry, oculoplethysmography or changes in intracranial arterial velocity (transcranial Doppler examination) during the Diamox (Acetazolamide) test. After release of carotid clamping or correction of a "hemodynamically significant" stenosis, increased cerebral blood flow can be observed, with sometimes a "cerebral hyperperfusion" syndrome similar to that of hypertensive events which exceed the capacities of cerebral arterial autoregulation.

Brain Ischemia↗