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Biomedical subjects

U Laux

Publications and source records attributed to U Laux.

At least 19 recordsLinked to original sources
PubMed1980

[Physiological side differences in fluorescein inflow into eyes (author's transl)].

Rapid-sequence fluorescein angiography was performed simultaneously on both eyes of each of 241 healthy individuals in order to analyze and compare dye inflow patterns in the eyes of each subject. The many uncertainties of successive investigations resulting from uncontrollable changes in systemic circulation parameters between the two angiographies were thus eliminated. In over 90% of the subjects there was no difference between the two eyes in respect of arm-fundus time nor the filling pattern of choroid and retina. A few subjects did show a difference, but this lasted for only one exposure and was normalized on the second exposure of the sequence. It is therefore concluded that side differences of the fluorescein inflow pattern on simultaneous bilateral angiography are highly suggestive of unilateral circulatory disturbances in the cervical, retinal or choroidal vessel. Such disturbances are practically certain if side differences last for more than just one exposure. In contrast, the filling pattern in cilioretinal arteries was very variable and over one third of the subjects presented with side differences between their two eyes. Therefore the filling pattern of these vessels cannot be used for diagnostic purposes.

Adolescent↗
PubMed1979

[Association of anomalous macula veins with deuteranopia (author's transl)].

A case is presented with large anomalous retinal veins arising above the macula and running across it downwards, towards and into the inferior temporal vein. There was a decreased visual acuity which could not be accounted for. The literature dealing with this rare anomaly is discussed. This is the first case in which the vascular anomaly was associated with deuteranopia.

Color Vision Defects↗
PubMed1979

Synchronous determination of retinal circulation times in both eyes.

Retinal circulation times of 44 healthy subjects (88 eyes) were measured simultaneously on both eyes by means of synchronous bilateral fluorescein angiography. "Circulation time" was defined as the time from the first arterial filling to the first fluorescence of the corresponding vein close to the disc margin. We found 1.2 sec for the superior temporal vessels, 1.3 sec for the inferior temporal, 1.3 sec for the superior nasal, and 1.4 sec for the inferior nasal vessels of the right eye. For the left eye these values were 1.2 sec, 1.2 sec, 1.4 sec, and 1.4 sec, respectively. No significant differences between the 2 eyes were demonstrable. It is concluded therefore that in cases of monocular disturbances of retinal circulation the other eye can serve as a reliable standard when measurements are performed simultaneously on both sides. The many uncertainties of successive examinations caused by uncontrollable systemic circulation changes are thus eliminated.

Adult↗
PubMed1979

[Dye-filling patterns in routine serial angiograms].

Rapid-sequence fluorescein angiograms of 127 healthy eyes with cilioretinal arteries were analyzed with regard to the time of dye entry into the central retinal artery, the cilioretinal artery and the choroid. In younger patients up to age 49) the cilioretinal artery filled simultaneously just as often as prior to the central retinal artery (42.9% and 41.4%, respectively); only rarely (15.7%) was a later filling noticed. In older persons (50 years of age and older) this filling pattern was reversed. The cilioretinal artery most frequently filled later than the central retinal artery (48.7%) and only rarely prior to it (15.8%). Similar results were obtained when comparing the filling time of the central retinal artery with the first choroidal fluorescein. With increasing age the circulation in the choroid and the cilioretinal arteries slows down in comparison to the central retinal artery, due to sclerotic vessel changes which have been shown to be much more pronounced in the choroidal vessels than in the retinal vessels. These findings are important for the understanding of age-related diseases of the optic nerve head, which derives almost all its blood supply from the choroidal circulation.

Adolescent↗
PubMed1978

[Improved rapid sequence fluorescein angiography for retinal circulation studies (author's transl)].

Investigations of the initial phase of the angiogram and measurements of retinal circulation times require a rapid sequence angiography. Although almost all of the available cameras allow for 2 or 3 exposures per second, such rapid sequence angiograms are not performed routinely. Especially the patient's stress from 2 or 3 flashes per second is considerable making these investigations very difficult. We have introduced 3 modifications of the regular technique of rapid sequence angiography that greatly facilitate the procedure so that large numbers of patients can easily be investigated in clinical routine. 1. The regular fixation target in the Zeiss fundus camera has been replaced by a special diaphragm (Fig. 1) which will exclude part of the fundus from exposure to light. This way pictures are taken only of the disc and the peripapillary area which are most important for circulation studies. After completion of the rapid sequence the diaphragm can easily be removed and further pictures taken of regular size. 2. The fluorescein is injected by means of an automatic injector (Fig. 2) in order to obtain a concentrated dye bolus. 3. The sequence of the angiogram is controlled by an electronic timer (Fig. 3 a and b). The photographer can thus fully concentrate on the camera adjustment without worrying about dye injection or triggering the camera. The perfect standardisation obtained will facilitate the measurement of different circulation parameters later on the film.

Fluorescein Angiography↗
PubMed1978

[Retinal circulation times as determined by fluorescein angiography (author's transl)].

Using a standardized technique of rapid fluorescein angiography applying a special diaphragm in the camera to reduce the patient stress by the frequent flashes and an automatic dye injection retinal circulation times of 173 healthy eyes were measured and statistically analysed. Circulation time was defined as the time interval between first visible arterial and venous fluorescence of corresponding vessels near the disc margin. The circulation time for the temporal vessels (1.1--1.2 s) was significantly faster than that of the nasal vessels (1.3 s) whereas there was no significant difference between the upper and lower main vessels. The very short circulation times are caused by short circuits near the disc. The difference between the shorter temporal and longer nasal times is caused by the macular circulation. It would therefore be more accurate to speak of peripapillary circulation times or of circulation times of the posterior pole of the fundus.

Capillaries↗
PubMed1977

[Ear to retina time and ophthalmodynamometry after ligation of the common carotid artery in rabbits (author's transl)].

Unilateral ligation of the common carotid artery was performed in rabbits. Before ligation, immediately thereafter, and 6 weeks later the ophthalmic artery pressure was determined and at the same time a synchronous measurement of the ear to retina time was done on both sides. The results were statistically analyzed (Tables 1-4). Ligation of the right common carotid artery resulted in a highly significant difference in systolic ophthalmic artery pressure between the two eyes of 16.4 mm Hg, and in diastolic pressure one of 13.0 mm Hg. After ligation of the left similar pressure differences of (systolic) 17.8 mm Hg and (diastolic) 15.2 mm Hg were shown. During the following 6 weeks these differences decreased considerably, to 41.5% and 29.2% after ligation on the right and to 33.5% and 36.6% after ligation on the left. The ear to retina time was markedly prolonged on the side of the ligation. This resulted in a highly significant side difference of 0.42 s immediately after ligation on the right common carotid artery and 0.4 s immediately after ligation on the left side. After 6 weeks these differences were only slightly reduced, to 80% and 72.7% respectively. These animal experiments demonstrate clearly that an acute occlusion of one common carotid artery in rabbits can easily be diagnosed by ophthalmodynamometry as well as by synchronous measurement of the ear to retina time. In chronic occlusions determination of the ear to retina time is superior to pressure measurement. This is of particular interest since in these experiments an ophthalmodynamometric method was used that is much superior to the clinical method of ophthalmodynamometry.

Animals↗
PubMed1976

[Standardized fluorescein injection in serial angiography (author's transl)].

Maximal initial dye concentration in the retinal arteries is desirable for high quality fluorescein Angiograms and is essential for circulation studies. Such high initial dye concentrations can only be achieved by a very rapid fluorescein injection technique necessitating an automatic injector. A reliable easy to use "spring-injector" has been designed for clinical use (Figs. 1 and 2). A disposable syringe is driven by a spring contained in a metal cylinder. Microswitches are activated by the piston of the injector triggering one exposure each at the beginning and at the end of the injection. Time and duration of the injection are therby permanently documented on the film. The "Terumo Disposable Syringe 10 cc" is used routinely. By interposing a plastic connector between syringe and injector-piston the injection-volume can be reduced to 5 ml. With diffferent connectors one can inject an volume desired up to 10 ml. The duration of the injection can be varied by using different intravenous catheters. Routinely the "VYGON Trocaflex catheter Nr. 125.16" with a needle diameter of 1.1 mm and a length of 30 cm is used resulting in an injection time of 10 ml/1.0 sec or 5 ml/0.5 sec. The largest Trocaflex catheter (No. 125.20) will shorten the injection time to 10 ml/0.5 sec and 5 ml/0.25 sec respectively. Even faster injections can be achieved by shortening the catheter or by using a stronger spring. With the described injector, high-speed, well-standardized fluorescein injections are possible. The intravenous catheter makes parvenous injections impossible and will allow for repeated angiograms even on different days without the need for a new venous puncture.

Fluorescein Angiography↗
PubMed1975

[Aqueous humor pH in experimental lye burns and influence of different treatment measures (author's transl)].

300 rabbit corneas were burned for 1 minute by applying a filter paper of 10 mm diameter soaked in different concentrations of NaOH. The aqueous humor pH was then measured at certain time intervals and after different treatment methods until the physiologic pH of 7.6 was reached. The results were statistically analysed. Group 1, 2 and 3 were burned in 1n NaOH, 3n NaOH, and 6n NaOH respectively without any treatment. In these groups a "therapeutic" pH-level of 8.5 was measured on an average 0.5, 2.5 and 5 hours after the burn (Table 1 and Fig. 2). Group 4 and 5 again were burned with 6n NaOH. In group 4 the burn was followed by constant irrigation with physiologic saline solution by means of the Morgan Therapeutic Lens (Fig. 1a and b). With this regimen a pH of 8.5 was reached after 2.5 hours (Table 1 and Fig. 3). In group 5 the physiologic saline solutions was replaced by a buffer solution (Isogutt) and a pH of 8.5 was measured after only one hour (Table 1 and Fig. 3). Based upon these results it is felt that severe lye burns should be treated by constant irrigation with a buffer solution for several hours. A treatment that can easily be performed by use of the Morgan Therapeutic Lens.

Animals↗