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J G Schmidt

Publications and source records attributed to J G Schmidt.

At least 37 records · Page 2Linked to original sources
PubMed1987

On the recovery of the electroretinogram after removal of intravitreal zinc particles.

The influence of intravitreal zinc particles (1.3 mm2) in the eyes of rats caused the amplitudes of the electroretinogram to decrease to about 50% of the initial values within 24 hours, whereas the prolongation of the peak times began only on the third day after particle implantation. The removal of the zinc particles after 30 days led to only partial recovery of the amplitudes, whereas the peak times reached normal values. Dissociated behaviour of the amplitudes and peak times as described here was not found in earlier experiments with intravitreal iron, copper or lead particles of the same size. The extraction of intravitreal zinc particles (1.3 mm2) one day after implantation resulted in a recovery of the amplitudes up to 85%.

Animals↗
PubMed1987

Intravitreal cupriferous foreign bodies: electroretinograms and inflammatory responses.

This is a report on the effects of various equally sized copper alloys implanted in the vitreous body of 52 Wistar rats. The main results are as follows: (1) The alloy of 99.9% copper with 0.1% silver (A) destroyed the electroretinogram (ERG) faster than specially purified copper (B). In contrast, copper-zinc alloys (C and D) affected the ERG more slowly than B. This effect is more obvious in alloys containing a large amount of zinc (D). (2) The degree of complication in the anterior segment (iridocyclitis, corneal opacity, hypopyon) and in the vitreous body (intensity and rate of opacity) depend essentially on the type of alloy. The frequency and extent of inflammatory responses decreased in the following order: alloy A, B, C and D.

Alloys↗
PubMed1987

Surface area sized of intravitreal iron wires: their effects on the electroretinograms of rats.

UNLABELLED: The electroretinogram (ERG) was recorded 20 times over a period of 360 days in 26 albino-rats with implanted intravitreal iron wires ranging in size between 0.15 and 1.2 mm2. RESULTS: (i) The a- and b-wave amplitudes decreased rapidly within one day after iron wire implantation. During the following week the amplitudes recovered to some extent. In the course of the next few months the a- and b-wave amplitudes of the eyes implanted with the largest iron wires (1.2 mm2) decreased steadily to about 20% by the end of the observation time, whereas in the groups containing smaller iron wires the electroretinographic changes were limited. (ii) Implantation of equally-sized glass splinters reduced the a- and b-wave amplitudes to 65-75% in comparison to the intact fellow eye. Fast recovery of both potentials to 83-93% followed within two weeks. The mean values of the a-wave amplitudes reached nearly 100%, those of the b-wave 90-95% in the next month.

Animals↗
PubMed1987

On the recovery of the electroretinogram after removal of intravitreal copper particles.

This report details the influence of the time lapse and surface area size of intravitreal copper foreign bodies on the electroretinogram (ERG) and the recovery of the potentials after removal of the particles. Pure copper wires were implanted temporarily into the vitreous body of rat eyes in the area of the ora serrata and the values of the ERG were compared with those of the intact fellow eyes. In three different procedures with groups of 12 animals each the following results were obtained: (1) The metal toxicity of small copper particles (0.3 mm2) remaining one day in the vitreous body reduced the amplitudes of the a1-, a2-, and b-wave only 10% by the end of the observation time of 260 days, (2) The loss of ERG amplitudes increased to about 25% under the influence of larger copper particles (1.3 mm2; time lapse one day); and (3) Copper particles with an active surface of 1.3 mm2 remaining two days in the vitreous body caused a permanent loss of about 50%.

Animals↗
PubMed1986

On the recovery of the electroretinogram of rats after removal of intravitreal lead particles.

Lead particles (1.4 mm2) were implanted into the vitreous body of rats (16 animals) for 10 days and the recovery rate of the ERG was measured over an observation time of 190 days. After extraction of the lead particles the a- and b-wave amplitudes show a recovery from about 60% to 87% in comparison to those of the intact fellow eyes between the 60th and 90th day of observation. In earlier experiments the mechanical damage was measured using glass splinters. The differences between these values and the above mentioned recovery rate after lead extraction correspond to the irreversible component of the metal intoxication. In another group of rats (16 animals) the lead particle was not removed before the end of the observation time of 190 days. Subtracting these ERG values from those of the first group of rats after lead extraction one gets small differences which correspond to the reversible component of the metal intoxication. The irreversible lead intoxication is much less than that of intravitreal iron particles as we found under the same conditions. The lead particles we used, are larger than those we have to handle in clinical cases taking the relation of surface area size of the particle to the total bulbus weight. The ophthalmoscopical findings are described.

Animals↗
PubMed1986

Electroretinographic responses to the addition of nitrous oxide to halothane in rats.

The electroretinograms of 20 anesthetised but spontaneously breathing rats (Wistar) were recorded over a period of 60 minutes. Two anesthetical procedures were applied to each of these rats respectively: (I) halothane/nitrous oxide/oxygen (2% halothane in 0.81 N2O: 0.41 O2/min) and (II) halothane/nitrogen/oxygen (2% halothane in 0.81 N2: 0.41 O2/min). From the 10th up to the 60th min of anesthesia the ERG amplitudes decreased gradually (I: a-wave 17% and b-wave 14%; II: a-wave 15% and b-wave 12%). Body temperature was experimentally maintained at nearly 37.0 degrees C. Under considerable diminution in both procedures the frequency of respiration was significantly higher under procedure I in the first 20 minutes only. Under procedure I the b-wave amplitudes were significantly higher in contrast to procedure II. This occurred at all applied stimulus intensities (6; 24; 100; 400 and 1600 Lux at the cornea). The a-wave amplitudes and the peak times of the a- and b-waves did not show any significant differences between the two experimental conditions. These ERG responses to nitrous oxide in addition to halothane are discussed on the basis of the respiratory, circulatory and cerebral effects of these anesthetics.

Anesthesia, General↗
PubMed1986

[Effect of decadron phosphate on ophthalmoscopic changes in the rat eye with intravitreal brass wires].

This paper reports on ophthalmoscopic findings after implantation of 0.3 mm2 copper-zinc wires (85:15) into the vitreous body of rat eyes (2 groups of 11 animals each) and the influence of daily administration of Decadron-Phosphate, equivalent to 0.05 mg dexamethasone. This drug, injected subconjunctivally over a period of 10 days, reduces the vitreal opacities and both retinal as well as vitreal vascularization, but increases the tendency of the foreign bodies to migrate. The dose-dependent decline in bodyweight gain is an indicator of the drug's systemic effect. In order to distinguish mechanical damage from the metal intoxication, glass splinters of the same size and shape were implanted in a further series of experiments, for the purpose of comparison.

Animals↗
PubMed1986

[Regeneration capacity in retina and vitreous body changes following extraction of intravitreal copper particles].

On the basis of experiments with 42 rats, quantitative statements are made regarding the influence of surface area and dwelling time of intravitreal copper particles on the electroretinogram. The influence of these factors on the extent of recovery of function after extraction of the foreign body is demonstrated. The rate of mental intoxication (metallosis retinae) is indicated separately from the mechanical damage. Ophthalmoscopic findings are also described. The practical relevance of these results to the clinical situation is discussed in detail in connection with earlier reports.

Animals↗
PubMed1984

[Nodular fasciitis of the orbit].

A 46-year-old patient is described who presented with a pea-sized painless tumor in the upper eyelid. Surgical excision and histologic diagnosis revealed a proliferating spindle cell tumor with an inflammatory reaction, which was identified as nodular fasciitis. Differential diagnosis, incidence of such tumors in the orbit and treatment are discussed.

Diagnosis, Differential↗
PubMed1976

The value of electro-oculography for the diagnosis of tapeto-retinal degenerations.

The particular value of the EOG for diagnosis and prognosis has been demonstrated with the findings and case histories of seven patients. We have shown (1) that the EOG in connection with the ERG has contributed decisively to the differentiation of numerous types of tapeto-retinal dystrophies; (2) that the EOG is, as a rule, very valuable in distinguishing between tapeto-retinal dystrophies and flourishing or healed chorioretinitis, and (3) the different values of the other examination methods (visual field, colour vision tests, dark adaptation, angiography) in comparison with the electrophysiological methods. We have used the same methods as were used in previous examinations.

Adult↗