Biomedical subjects

D Vecchi

Publications and source records attributed to D Vecchi.

5 recordsLinked to original sources

PubMed1986

Active blockage and rest position nystagmus: electromyographic demonstration of two types of ocular induced head-turn.

A differentiation of two types of head-turns due to nystagmus, by means of electromyography (EMG) is demonstrated in this paper. The first type is represented by patients who actively block the nystagmus, by means of an increase of discharge of the extraocular muscles who are synergistic and responsible for the head-turn. This block has the same features of the block of nystagmus in convergence and usually exceeds 10-15 degrees from the primary position. The second type is made out of patients whose head-turn is explained with the null-position of Kestenbaum. Here the nystagmus simply disappears in the position of head-turn, which usually is of no more than 10-15 degrees. Both types of patients show the same electronystagmographic features in the position of head-turn. This differentiation is useful from the clinical standpoint. In fact, only the first type of head-turn may require, besides a classical Anderson or Kestenbaum procedure, also a posterior fixation suture according to Cüppers. This operation would be useless in the second type of head-turn. Clinical signs useful for differentiating these two types of head-turn are presented as well.

Adult↗

PubMed1986

Device for eliminating corneal light reflections during recording of lateral images with a slit lamp.

Corneal reflections produce defects in photographic sections of the lens taken with a slit-lamp biomicroscope for computerized densitometric analysis of cataract opacity. A simple and workable, adjustable antireflection device was built that can be easily adapted to photographic slit lamps, a common instrument in ophthalmology equipment. The slit lamp is a versatile tool for photographing structures in the anterior segment of the eye, particularly the lens. Corneal reflections are eliminated for angles between the light band and a photograph plane ranging from 20 degrees to 90 degrees, with the light band no greater than 0.5 mm and the corneal curvature about 7.6 to 7.9 mm. The device acts by blocking aberrant light rays from the light source that would otherwise be reflected by the mirrorlike surface of the cornea and enter the objective lens. Here we present a prototype designed for the Zeiss slit lamp.

Cornea↗

PubMed1986

Modifications of the slit lamp for digital image processing of the anterior segment of the eye.

The Zeiss slit lamp has been modified in order to extend its use to measurements of lens transparency. Two major modifications have been introduced: (1) a support for a high-sensitivity TV camera that is connected to an image processing system; (2) two potentiometers for recording electrical signals proportional to the rotation angle of the slit-supporting arm with respect to the visual axis and the slit tilting angle. As a result, the slit lamp output consists of three signals; one TV signal for the images and two analog signals for measurement of the angles. With the aid of an image-processing system connected to a minicomputer, software has been developed to enable the operator to acquire reliable digital images of the anterior segment of the eye in real time. The software provides the user with an easy-to-follow menu.

Anterior Eye Segment↗

PubMed1984

Improvements in clinical electronystagmogram analysis.

The authors apply the technique of amplitude histogram analysis to the clinical electronystagmogram (ENG). After a brief survey of the underlying concepts, some typical normal and pathological ENG records are discussed. Comparison of advantages and disadvantages reveals that the quoted technique may be suitable to be profitably introduced in clinical practice.

Electronystagmography↗

PubMed1983

Reliability of photometric measurements in the Zeiss fundus camera.

The authors test the hypothesis of systematic errors in photometric and/or densitometric measurements performed by Fundus camera equipment. By means of 2 different methods (reflection and transmission) the non-uniformity of light-distribution on sample surfaces placed in front of the fundus camera is shown. The consequent point by point variability in retinal illumination can be defined as the 'retinal shading problem'. This conclusion must be taken into account when equidensitometric measurements are carried out on eye fundus images with fundus camera, by photographic, cinematographic or TV techniques.

Cineangiography↗