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Biomedical subjects

R D Lepper

Publications and source records attributed to R D Lepper.

10 recordsLinked to original sources
PubMed1984

[Digital analysis of ultrasound M images for determining the dynamic behavior of the posterior ocular wall].

A computer-assisted interactive method for M-scan analysis is presented. The digital M-scan, which is taken from the posterior wall of the human eye - in vivo - , is a sequence of digitised, broadband r.f.-time amplitude echograms (center frequency: 15 MHz). The effect of pulsation in the normal posterior wall of the eye and the dynamic changes and tissue movements after stress conditions can be pointed out and estimated quantitatively. A detected set of dynamic features can be used for an exact determination of the layers of the posterior ocular wall. For the indication of the dependence between changes of the thickness of the layers and the heart rate, the finger pulse is digitised and stored synchronously to the echograms. Good correlation will be expected for the movements in the choroid of the eye and the heart rate. The registration of the dynamics is performed in the color-coded M-scan by an adapted image processing software. Results of the M-scan analysis are presented as examples of the normal posterior wall.

Choroid↗
PubMed1984

Computer-aided ultrasonic measurements of the corneal thickness.

This report regards the measurements of the central corneal thickness by means of a computerized ultrasonic biometry system that had been developed by the authors. The characteristics of this system are: (a) a data rate of 10 measurements/s (reduced from the technical maximum of 800/s); (b) a resolution of 0.02 mm, and (e) statistical evaluation of data by automatic measurement histogram. The preliminary results on models and living human eyes suggest an equivalence of the improved ultrasonic measurement in cases where an immersion technique is feasible, with optical methods usually applied in clinical routine.

Anthropometry↗
PubMed1980

[New technique of ultrasonic biometry (author's transl)].

A new measuring system for echo return times is described, which renders it possible to measure simultaneously the three axial lengths of the living eye (length of cornea plus anterior chamber, length of the lens and of the vitreous) with ultrasound in real time and to process the data numerically. The repetition rate for the measurements is optimized up to the limit: each transmitted wave is registered. The computer either generates a measuring protocol with statistical data (mean value, standard deviation) or the variation of the three echo return times is displayed graphically. In clinical practice the unit is used routinely for rapid determination of optimal implant lenses, etc.

Anterior Chamber↗
PubMed1977

[Ultrasound diagnosis in simulated middle-ear-effusions in isolated human temporal bones (author's transl)].

By means of simulated middle-ear effusions in isolated human temporal bones it could be demonstrated, that ultrasonic echos of the drum show typical patterns if the middle-ear is filled with fluid or not. In normal air-filled drums there is only the echo of the tympanic membrane, whereas in fluid-filled drums a second echo from the bony medial wall of the tympanon appears. --A method is described how to perform ultrasonograms under visual observation of the tympanic membrane.

Ear Diseases↗