Search PubMed⌕ Search

Biomedical subjects

W Vilser

Publications and source records attributed to W Vilser.

36 records · Page 2Linked to original sources
PubMed1986

Measurements of retinal microcirculation in retinal vessel occlusion before and after treatment.

Blood flow, arterial velocity, and vascular diameter were measured in patients with retinal vessel occlusion before and after treatment, especially after light coagulation. The mean values in the patient group showed significantly reduced blood flow and velocity compared to the normal group. The mean group difference before and after therapy revealed that while there is an increase in blood flow after treatment, the normal value is not reached. Individual patient values indicated both increased and decreased blood flow and velocity after treatment as compared with the values before therapy. There are various stages in microcirculatory disease and the microcirculation also behaves differently after treatment, which could be observed by measurement in vivo of the physiological flow parameters.

Adult↗
PubMed1986

[Clinical interpretation of retinal circulatory measurements. I. Technical measurement possibilities and clinical interpretation aid].

The present possibilities to measure blood flow and other magnitudes of retinal microcirculation in vivo are discussed. On this basis, a simple model designed for retinal microcirculation is presented as a tool for the clinical interpretation of measuring results. Based on the experience of over 200 measurements of retinal microcirculation magnitudes, subsequent reports give a clinical interpretation of measuring results, utilizing the measuring models presented. Thus, it is intended to demonstrate the actual clinical significance of such measurements.

Blood Flow Velocity↗
PubMed1986

[Clinical interpretation of retinal circulatory measurements. II. Blood flow].

Beginning as early as the mid-4th decade of life, an age-dependent reduction in retinal blood flow has to be considered an essential risk factor for disorders of retinal microcirculation. Blood flow measurements are a valuable, but not the sole criterion of microcirculatory disorders. While in retinal occlusive diseases blood flow is a valuable indicator of the severity of microcirculatory disorders, the latter can also occur in the presence of normal and elevated blood flow values. Shifts of the metabolic activity of the retina and changes in the metabolic activity of the retina and changes in the metabolic conditions have to be taken into account when a clinical interpretation is given.

Diabetic Retinopathy↗
PubMed1986

[Clinical interpretation of retinal circulatory measurements. III. Blood flow velocity and vessel diameter in normal persons and in patients with venous occlusive diseases].

Based on results from measurements of arterial blood velocity, arterial and venous diameters of major segmental retinal vessels in normal persons and in patients with venous occlusive diseases and in continuation of the two preceding parts of this series of articles, further possibilities for the differential diagnosis of measurements of retinal microcirculation magnitudes are discussed. Whereas the measurement of blood velocity is an important criterion for the assessment of the stasis conditions and the arterial involvement in an occlusive disease, the diameters of the vessels offer essential suggestions to local regulative processes. In this connection, a dependence on pH of the contraction state of the smooth vascular musculature detected in porcine coronary arteries is presented. By its transmission to the arterial retinal vessels, it is possible to unequivocally clarify the local regulative and pathological behavior of arterial retinal vessels in terms of flow physiology.

Blood Flow Velocity↗
PubMed1986

[Clinical interpretation of retinal circulatory measurements. IV. Photocoagulation in diabetic retinopathy and venous occlusive diseases].

Based on the pathomechanism of diabetic retinopathy, the effect of photocoagulation on retinal microcirculation as assessed by measurements of retinal microcirculation magnitudes is discussed. The clinico-experimental results support the opinion that an essential effect of photocoagulation is due to an improvement in the flow conditions of the noncoagulated central retinal area with regard to metabolic exchange and stasis situation by the coagulation-induced occlusion of peripheral capillary areas. Further clinico-experimental measurements of retinal microcirculation magnitudes for the assessment of the behavior of microcirculation after photocoagulation in venous occlusive diseases of the retina are presented. It is shown that retinal microcirculation immediately after photocoagulation reacts by transitory instationary flow conditions; in this period it is quite possible that an additional blood flow reduction over several days will occur. In particular, the effect of photocoagulation in venous occlusive diseases with narrow arterial vessels is discussed. It is emphasized that with regard to the therapeutic effect of photocoagulation as well as to the discussion of pathomechanisms, apart from blood flow, the differentiated behavior of single retinal vascular areas, such as arteries, arterioles, capillaries, venules and veins, requires more attention. Particularly with this in mind, substantial improvements in differential diagnosis and treatment of retinal circulatory disturbances may be expected from measurements of retinal circulation magnitudes.

Adult↗
PubMed1985

Measurement of flow-physiologic parameters of retinal blood circulation in type 1 and 2 diabetics before and after photocoagulation.

In seven diabetics of type 1 and seven of type 2, the flow physiologic magnitudes were measured in a retinal quadrant before and after photocoagulation. The segmental blood flow, the arterial flow velocity, and the diameters of artery and vein are smaller after photocoagulation than before. Investigations into the time course of the flow-physiologic parameters following photocoagulation show that the flow-physiologic values are stationary about 2 weeks after photocoagulation.

Adult↗
PubMed1985

Reflectance spectrophotometry in the human ocular fundus.

Spectrometric investigations were carried out in normal human maculae and optic discs and in those with pathological findings (50 eyes in total). Reflection spectra were measured by illumination of various points of the fundus, using a highly sensitive photon-counting technique. It is necessary to distinguish diffusely reflected light from regularly reflected light, as we found marked differences in the spectra of diffusely reflected light between normal eyes and those with pathological findings. In optic atrophy cases, the intensity of light reflected from the optic disc (510-600 nm) was remarkably higher than normal. In findings of proliferative diabetic retinopathy, the reflected light intensity showed a steeper slope, beginning at 580 nm, in comparison with normal findings.

Diabetic Retinopathy↗
PubMed1983

[Measurement of flow physiology of the large vessels in retinal circulation in type 1 and type 2 diabetics].

Segmental blood flow, velocity, and vessel diameter were measured in 21 eyes of diabetic individuals with diabetes type 1 and 2. The results for arterial blood flow, velocity, arterial and venous vessel diameter in diabetes show significant differences from the results measured in normal individuals. These flow magnitudes, excluding arterial diameter, significantly depend on the duration time of diabetes. The retinal blood flow magnitudes alter before the marks of diabetic retinopathy are visible. There are differences between the results in diabetes type 1 and type 2 regarding dependence on the duration time of diabetes.

Adolescent↗
PubMed1983

[Evaluation of fluorescein angiograms using the multitemporal technic].

If there are differences in the density of black-and-white photographs of the fundus oculi taken at different times, they may be transformed into color differences by means of the multitemporal technique. A multitemporal picture is obtained by additive color mixing of black-and-white photographs transilluminated at the same time with one primary color each. Since, in a serial angiogram, the interrelation between the film density and the passage of the fluorescein concentration in the fundus oculi is known, it is possible to draw conclusions from the multitemporal picture regarding phase differences and changes in the curve shape of the fluorescein concentration.

Diagnosis, Differential↗
PubMed1981

[Principal possibilities and limitations of fluorescent angiographic procedures for the measurement of the flow-physical magnitudes of the retinal circulatory system (author's transl)].

Flow-physical magnitudes are presented that describe the retinal circulatory system. The principal possibilities and limitations of fluorescent angiographic procedures for the measurement of these magnitudes are discussed. On this basis, we compare fluorescentophthalmoscopic measurements of time, serial angiography, and cinematography with densitometric evaluation of the negatives, integral fluorophotometry, 'two point' photometry, and the application of television with evaluation of the video signal.

Fluorescein Angiography↗
PubMed1979

[Length measurements by rocking-plate micrometry at the fundus of the human eye (author's transl)].

An additional unit which can be used for length measurements at the fundus of the human eye is described for the ophthalmoscope. The principle of measurement is based on optical displacement of the measuring object to itself. The optical displacement of picture points is made possible by the use of a tilting flat glass plate in the intermediate image plane of the eyepiece. The relation between the optical displacement of picture points and the measuring movement is sufficiently linear for the described device.

Fundus Oculi↗
PubMedDate not supplied

Retinal vessel reaction to short-term IOP elevation in ocular hypertensive and glaucoma patients.

PURPOSE: Regulation of ocular blood flow might be impaired in glaucoma patients. We compared the reaction of retinal vessels to a short-term increase of intraocular pressure (IOP), using a retinal vessel analyzer (RVA), in normal volunteers, ocular hypertensive patients (OH) and primary open angle glaucoma patients (POAG). METHODS: Ten healthy subjects (56+/-8 years, IOP 13.7+/-1.6 mmHg), 10 OH patients (55+/-12 years, IOD 23.4+/-4.1 mmHg) and 11 POAG patients (60+/-11 years, IOP 23.3+/-1.95 mmHg) were evaluated. Arterial and venous retinal vessel diameter was measured continuously before, during and after raising IOP to suprasystolic values by the suction cup method, described as ocular oscillo-dynamography. RESULTS: The change in vessel diameter after the IOP rise differed in its temporal sequence and in absolute values depending on the group examined. In the retinal branch veins the reduction of vessel diameter during the IOP rise was significantly different in POAG (0%+/-6.7) and volunteers (-6.7%+/-8.5; p = 0.06) and in POAG and OH (-6.7%+/-7.0; p = 0.04). At 70-130 sec after IOP increase a dilatation occurred, again differing significantly in POAG (+5.8%+/-3.9) and volunteers (+9.7%+/-4.3; p = 0.03). Systemic blood pressure did not show any significant differences between groups or during the course of the examination. DISCUSSION: At short-term rise in IOP leads to less retinal vessel reaction in POAG patients than in volunteers and OH. This might be due to impaired autoregulation to ocular perfusion changes in POAG patients.

Blood Flow Velocity↗
PubMedDate not supplied

Blood pressure effects on retinal vessel diameter and flicker response: a 1.5-year follow-up.

PURPOSE: The study examined the influence of individual blood pressure changes overtime on retinal vessel diameter and the latter's response to flicker light. METHODS: The diameter of a retinal arterial and venous segment was measured continuously on-line with a Dynamic Vessel Analyzer in 20 patients twice (mean interval between examinations of 24 months). Eleven patients had no cardiovascular disease. Nine patients had arterial hypertension and were untreated at the time of the first measurement; at the time of the second measurement they were undergoing various antihypertensive therapies. Each test consisted of a 50-s baseline plus three 20-s periods of flicker stimulation followed by an 80-s period of observation. During the examinations the blood pressure was measured at 1-minute intervals. RESULTS: In the hypertension group changes in the mean arterial blood pressure (MAP) correlated significantly with changes in the arterial baseline diameter (y = -0.1 - 0.37x, r =0.74, p (increase) <0.03). A comparison of the two measurements showed no such relationship in the group of cardiovascularly healthy subjects. The venous baseline and the arterial and venous flicker response did not change significantly in either group between the two measurements and showed no relationship to blood pressure changes. CONCLUSIONS: In hypertensive subjects, long-term therapy-related changes in blood pressure induced a change in the arterial baseline by approximately +3.7 microm/-10 mmHg MAP. An influence of lowering MAP to the arterial flicker response could not be detected.

Antihypertensive Agents↗
PubMedDate not supplied

Filtering properties of an adaptive trend operator and the application for determining the arterial blood velocity in retinal vessels.

This study deals with methods focused on estimating blood velocity. The estimation of the linear trend function of a non-stationary signal based on the adaptive recursive estimation of the mean value function is used for the determination of the time delay of two indicator dilution curves. The filter property of this trend operator depends on the choice of a constant parameter c, the so-called adaptation factor. The functional connection between the filter property and the adaptation factor is considered in such a way that an objective calculation of arterial blood velocity in retinal vessels is possible.

Algorithms↗