PubMed Health⌕ Search

Biomedical subjects

J Röver

Publications and source records attributed to J Röver.

17 recordsLinked to original sources
PubMed1988

Check-size specific changes of pattern electroretinogram in patients with early open-angle glaucoma.

The pattern electroretinogram was recorded in patients with initial stages of visual field defects due to open-angle glaucoma and in age-matched normal subjects. Both normal subjects and glaucoma patients had a visual acuity above 0.8. Counterphasing checkerboard patterns were used as visual stimuli with a range of check sizes from 0.8 degree to 15 degrees at 7.8 reversals/s. Whereas the amplitude in glaucoma patients was nearly normal for large check sizes, it was significantly reduced for small check sizes (p = 0.003). Possibly two separate mechanisms that generate the pattern electroretinogram for small and large checks are differentially affected; they may be related to the magnocellular and parvocellular systems. The difference between normals and glaucoma patients was even more significant when the ratios of the amplitudes at small and large check sizes were compared (p less than 0.0002). When this ratios is used, the amplitude variability can be partly overcome and the pattern electroretinogram can be a sensitive indicator of ganglion cell function.

Aged↗
PubMed1987

Pattern electroretinogram plus visual evoked potential: a decisive test in patients suspected of malingering.

Along the processing chain in the visual pathway the pattern electroretinogram (PERG) is a better indicator of the peripheral function than the visual evoked potential (VEP). Therefore the PERG and the VEP will be impaired equally by disturbances before the ganglion cell layer (e.g., blurred image or retinal disease) and differently by further centrally located diseases (e.g., tumor compression of the optic nerve). Thus in patients complaining of reduced visual acuity who show disturbed VEP but a normal PERG, malingering can be definitely ruled out. Representative combinations of PERG and VEP findings are described.

Adult↗
PubMed1978

The registration of slow ERG potentials of the perfused extracorporeal bull's eye.

Enucleated bull's eyes were perfused with blood and ERG recorded, with special attention paid to the slow components. When the blood flow was interrupted, the ERG components vanished in the following order: b wave, c wave, off-effect (d wave), and a wave. When the perfusion was continued afterward, we saw a variation in the standing potential that hinted at the biochemical activities causing slow electrical potentials of the retina.

Animals↗
PubMed1978

Prenuclear paresis of homolateral inferior rectus and contralateral superior oblique eye muscles.

In a case of left inferior rectus paresis, it is demonstrated that the lesion must be prenuclear. On downward gaze, the left eye, although it reached the required target with a rapid saccade, drifted back towards the midline immediately afterwards. During the drift, several corrective saccades appeared. A dissociated "gaze paretic" nystagmus resulted. Synchronously, the right eye showed an incyclorotary nystagmus. We suspect a lesion of "tonic" fibers supplying the nuclear region of the left inferior rectus and the right superior oblique muscle.

Adult↗
PubMed1978

[Surgical or conservative treatment in orbital complications of sinus inflammations (author's transl)].

47 patients with orbital complications resulting from acute sinusitis have been treated at the Freiburg ENT Department during the last seven years. Acute ethmoiditis predominated in children, while pansinusitis was more common in adults. Previous sinus surgery did not prevent orbital complications arising from the same sinus. Orbital involvement was classified into periostitis, subperiosteal abscess and orbital cellulitis. According to clinical findings, 44.7% of the patients were managed conservatively. Prognosis was best in periostitis, whereas consersative treatment was unsafe in orbital cellulits. Children usually respond well to appropriate antibiotic coverage but the occurrence of common upper respiratory or anaerobic pathogens should be kept in mind.

Adult↗
PubMed1977

[The relationship of amplitude of visual evoked potentials to side length of rectangular stimulus pattern and to abruptness of stimulus alternation (author's transl)].

Cortical potentials evoked by viewing checkerboard pattern reversal stimuli as well as horizontal and vertical rectangular pattern reversal stimuli were recorded. The amplitude of the cortical evoked responses decreased with increasing side length of the rectangular pattern and decreasing velocity of the pattern reversal. Psychophysical and electrophysiologic findings are compared with these data and their clinical relevance is discussed.

Adaptation, Ocular↗
PubMed1976

[A canthi-skin electrode electroretinogram, independent of eye movements (author's transl)].

In order to avoid misinterpretation of ERG recordings taken with canthiskin electrodes, the potential deriving from the two electrodes was fed into a balancing amplifier that eliminated opposing voltages and amplified unidirectional voltages. During voluntary as well as nystagmus caused eye movements as well as those caused by nystagmus clearly distinguishable averaged ERG's were recorded.

Amplifiers, Electronic↗
PubMed1976

ERG of humans without C-wave.

Three out of 18 healthy persons investigated with the DC-ERG do not show a c-wave. By varying the adaptation levels and intensities of the stimuli four components in the human ERG can be isolated, the cone and rod late receptor potentials, the positive DC response, and a c-wave in most subjects. It is suggested that investigation of these components reveals a more detailed understanding of the pathophysiologic mechanisms in some retinal diseases.

Action Potentials↗
PubMed1976

Experiments concerning the human C-wave.

The dependence of the human c-wave from the step amplitude was studied qualitatively. The maximum of the c-wave is achieved with light stimuli longer than 10 sec. After a dark period of 10 sec a fully developed c-wave appears. Also, in response to a brilliant photoflash a c-wave could be recorded. The influence of a mobile pupil on the response in the DC-ERG is demonstrated. Responses of the retinal potential to square wave and sinusoidal stimuli of different period times have been registered.

Action Potentials↗
PubMed1976

A method for DC-ERG recording of alert humans.

We developed a technique for DC-coupled ERG recording of the alert human. The equipment consists of three units: a new cornea suction glass, a separate electrode, and a vacuum control device. We get stable recordings of more than one-half hour. By comparison with the EOG the identity of the EOG "on"-peak and ERG c-wave is assured. A fine structure of DC-ERG recording of 100 muV amplitude is closely correlated to the variation of the blood pressure in the ophthalmic artery. It may either be caused by the variable electric conductivity of the eyeball due to the blood pressure or it may reflect a variation of the retinal potential itself.

Attention↗
PubMedDate not supplied

On the movement of an iron particle in a magnetic field.

When moved by a magnetic field, an iron particle does not follow--quite oppositely to a widely held opinion--the field lines of the magnetic field. Rather, the force exerted onto the particle is directed towards the strongest increase of the magnetic field strength. The field lines and the force direction coincide only axially, radially they cross at an angle of 90 degrees. This has implications for ophthalmic surgery, when an extraction of iron splinters by a magnet is required.

Iron↗