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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.
Clinical evaluation of the function of the human retina by subjective, psychophysical tests can be complemented by objective, electrophysiological methods such as electroretinography. The electroretinogram (ERG) is a transient action potential generated by the vertebrate retina in response to light. Using standardized stimulation, after assessing the normal range of the ERG the investigator can establish early diagnosis, improve prognostic statements and document the course of retinal diseases. A method to selectively stimulate the rod- and cone-system, developed by Gouras and co-workers, has proved to allow further differentiation of heredodegenerative diseases of the retina. The ERG monitors objectively the function of the retina in infants uncapable of cooperating in psychophysical tests and in patients suffering from opacities of the optic media. ERG results should be evaluated synoptically with psychophysical data, ophthalmoscopy, fluoresceinangiography and possibly with EOG and VER recordings. Under experimental conditions the ERG serves to monitor the sensitivity of the retina in vivo as well as in vitro in physiological, pharmacological and toxicological studies.
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.
The authors report 20 cases of a syndrome named nephronophtisis and probably the same as the syndrome of medullar cystic disease. In all cases systematic electroretinography is performed. Nine cases show important deterioration of the outline. These cases can be included in the syndrome of Senior-Loken. The pathogenesis and familial character of this disease are discussed. The disturbances that appeared between the ocular and renal lesions suggest that there are probably two genes rather than a single pleiotropic gene.
Corneal electrodes useful for clinical electroretinography require topical anesthesia, interfere with vision, can abrade, and are not well accepted by most children and many adults. A low mass conductive thread, corneal (DTL) electrode is described and comparatively tested against the Burian-Allen electrode. The DTL electrode was found to have few of the limitations of the hard contact lens electrode. Furthermore, the DTL electrode signal quality was comparable to that of the Burian-Allen electrode and provided less between-patient variability.
Electroretinography revealed unsuspected night blindness in a patient who had suffered unilateral trauma. This case illustrates the importance of testing both eyes, even when one appears normal.
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The sensitivity of the blue cone system to low frequency flicker was tested with a psychophysical and an electroretinographical method. With the psychophysical method the subjects, members of a family with an inherited tritan defect, showed no sign of the presence of the blue cone system. With the electroretinogram the sensitivity was also significantly lower than in normal subjects, thus indicating a retinal origin of the tritan defect.
Colour vision defects were studied with an adapto-electroretinogram and with computer of average transients. ERG abnormalities were observed in achromatopsia, protanopia and protanomaly, which in deuteranopia and deuteranomaly the ERG was normal.
A gold foil ERG electrode is described. The device is inexpensive and simple to fabricate. Since it is hooked over the lower lid and makes minimal touch contact with the inferior limbal area, it can be used in circumstances which require prolonged testing of retinal function or in eyes with corneal pathology. Because the optics of the eye are not compromised, it is possible, with the use of appropriate stimuli and response-averaging techniques, to record local EFGs from relatively small retinal areas.
We exposed adult Rhesus monkeys who were fully dark adapted to paired flashes of white light which increased in intensity by increments of 0.1 log. units. As intensity increased, the amplitudes of both the cone and rod systems increased while the implicit times decreased so that the responses overlapped. High intensities produce a complex waveform which prevents separation of the rod and cone components or timing of the peaks. On the other hand, low intensities separate the early and late receptor potentials (L.R.P.) of cones and rods well and make it easy to time normal and pathological variations.
Ischemic retinopathy caused by central retinal artery occlusion destroys the inner retina including the inner nuclear layer. The b-wave and the oscillatory potentials in the ERG on-response and the d-wave and the oscillatory potentials in the ERG off-response are impaired. In EOG the amplitude of the slow oscillations and the standing potential are reduced. These findings can help to localize the generators of the different ERG- and EOG-components.
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Explore the source record for details and available documents.