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Biomedical subjects

R Stodtmeister

Publications and source records attributed to R Stodtmeister.

At least 73 records · Page 4Linked to original sources
PubMed1984

[Effect of various stimulation filters on tear film breakup time].

The tear break-up was determined in 30 patients with healthy eyes aged from 18 to 67 using two different types of filter combinations: (1) Schott Filter OG 530 and Schott Filter BG 12. (2) Schott Filter OG 530 and Zeiss Filter 485. In view of the filter characteristics, we expected a reduction of the variance of the tear break-up time with the second filter combination. This did not occur. There was no difference between the two filter combinations described according to the Wilcoxon Test on the 5 percent level. The reasons are discussed.

Adolescent↗
PubMed1984

[Filtering of the illumination of the operating field in microsurgery of the eye].

A filter (GG 475, 2 mm thickness) is presented with which the strain to which the patient's retina is subjected through the light used in surgery with operation microscopes can be reduced and which hardly impedes the surgeon's work at all. The effect of the filter on the sensitivity to damage of the retina and on the spectral sensitivity to brightness of the surgeon is demonstrated.

Filtration↗
PubMed1983

[Tear film break-up time with different stains].

The tear film break-up time is usually measured with the lacrimal fluid stained with fluorescein. With the staining methods currently recommended the break-up time is difficult to reproduce. In the study described here, the break-up times with different staining methods were compared. The reproducibility of the break-up time was measured shortly after staining and one minute thereafter. The best reproducibility achieved in this study was when the tear fluid was stained with 1 microliter of 5% Na-fluorescein solution.

Adolescent↗
PubMed1983

[Factors influencing the variability of tear film break-up time].

Tear film break-up time was measured on 6 consecutive workdays in 6 subjects without eye disease selected at random. The reasons for the wide range of scatter in the values measured were investigated by variance component estimation. It was found that intraindividual variance is by far the most important factor influencing the overall variance of the measured values. Therefore, caution is called for when judging the stability of the precorneal tear film by the tear film break-up time in healthy individuals.

Adolescent↗
PubMed1979

[Pilocarpin eye drops with a novel Pilocarpin polymeric salt (author's transl)].

A new pilocarpin salt was obtained by chemically linking pilocarpin to a polymere substance. By galenic processing to the respective emulsion, eye drops containing this pilocarpin salt were produced, which enable a retarded pilocarpin delivery in vitro. With respect to glaucoma therapy, clinical tests showed that frequency of application can considerably be reduced. In the present investigations on a collective of 30 normal volunteers the effect of a commercial aqueous pilocarpin solution on the IOP, pupillary diameter and accommodation was compared with that of the novel pilocarpin drops.

Adult↗
PubMed1978

Bandpass measurements in the electroretinographic electrode circuit.

In the experiments in this study band-pass measurements in electroretinographic electrode circuits were done for the first time, according to the information presently available to us. Our experiments show that in the much faster band-pass assessment by analysis of sawtooth and square waves no major error is involved. It may be concluded from our results that the recordings of ERG potentials are not changed by the characteristic properties of the electrode circuit in the frequency range of interest.

Adult↗
PubMed1978

Changes of the current pathways in the eye due to coating agents during electroretinography.

This study suggests a model by which we try to explain why coating agents habitually applied in electroretinography can change the amplitude of electroretinographic responses. The model is based on the results of experiments described in this paper. The accuracy of measurement in clinical and experimental electroretinography can be enhanced by applying this model.

Cellulose↗
PubMed1978

The influence of coating agents on the electrode circuit in electroretinography.

In electroretinography, coating agents are usually applied to improve the contact between the contact-lens electrode and the eye. These agents influence electroretinographic responses. In this experimental study we show that the characteristic properties of the electrode circuit are not influenced by the coating agent. Thus we conclude that these coating agents influence the eye itself. The mechanism of this interaction may be physical, or may be an unknown pharmacologic drug side effect.

Cellulose↗
PubMed1978

[EEG tracings in cerebral death (author's transl)].

In diagnosing electrocerebral silence (isoelectric tracing) the investigator must be sure to exclude the possibility of an artefact. With the methods available up to now for testing the proper functioning of electroencephalographic equipment it has not been possible entirely to avoid errors. A new method is described for the rapid and quantitatively exact testing of EEG equipment including electrodes and cables and the correct recording of isoelectric tracings.

Brain Death↗
PubMed1977

[A new method for calibration of electrophysiological recording systems (author's transl)].

The method described in this paper permits determination of amplification, band-pass properties, and electrode impedance in electrophysiological experimental setups. The battery powered test-signal generator drives square-wave current pulses through a 2 ohm resistance, which acts as a source of 100 muV p-p pulses. The 2 ohm resistor is wired in series with one of the electrode leads and remains there permanently. For calibration of the above-mentioned properties, one need only turn the generator on, without changing the measurement setup. By observing the shape of the square waves after passing through the system, it is possible to judge the band-pass characteristics of the entire system. Electrode impedance may be measured by putting a (variable) resistor in parallel with the preamplifier input. The test signal current is of the same order of magnitude as currents from biological signal sources. This method makes working with electrophysiological measurement systems which are used in electroretinography, electrooculography, and recording of visually-evoked cortical potentials in ophthalmology much easier.

Amplifiers, Electronic↗