[Multifocal oscillatory potentials (mfOPs) in patients with central retinal vein occlusion]. / Wieloogniskowe potencjaly oscylacyjne (mOPs) u chorych z zakrzepem zyly srodkowej siatkówki.

PURPOSE: To evaluate usefulness of multifocal oscillatory potentials (mfOPs) in diagnostics in patients with retinal vein occlusions. MATERIAL AND METHODS: The Visual Evoked Imaging System (VERIS, version 4.9) was used to stimulate the visual system to elicit mfOPs from 103 areas subtending the central 70-80 degrees of the retina in three patients with central or branch retinal vein occlusions. Two stimulating conditions were used. For each subject, the mean first- and second-order kernel responses from occlusion area, were analyzed and compared with the fellow eye and control subjects results. RESULTS: In retinal areas without circulatory disturbances in fluorescein angiography all mfOPs components were present. In a patient with branch retinal vein occlusion in the area without capillary perfusion mfOPs responses were not detectable. CONCLUSIONS: The mfOPs are in a large extent dependent on a proper retinal circulation. The recording of mfOPs may be useful in clinical diagnosis, to asses circulatory disturbances in internal layers of the retina and in differentiation of ischemic from non ischemic retinal vein occlusions.

[Multifocal electroretinogram]. / Elektroretinogram wieloogniskowy

The paper presents current state of knowledge regarding multifocal electroretinography (mfERG). The theoretical basis of this technique, procedure, methods and examples of use in clinical diagnostics are presented.

Cone selective adaptation influences L- and M-cone driven signals in electroretinography and psychophysics.

To assess the influence of selective adaptation of long (L) and middle (M) wavelength sensitive cones with electroretinography (ERG) and psychophysics, a novel adaptation procedure was developed, which comprises a selective and quantifiable change in the state of adaptation in the different cone types. One adaptation condition was used as a reference. In four additional conditions, the M-cones or the L-cones were selectively adapted, so that they absorbed either more or less photons. At each of these five states of adaptation, the ERG response amplitudes to 30Hz L- and to M-cone selective stimuli were measured. Furthermore, the psychophysical sensitivities to L- and M-cone selective stimuli were measured at different temporal frequencies. In subjects with normal color vision, adaptation can have a strong influence on the L- and M-cone driven response amplitudes in the ERG and on both the L- and the M-cone sensitivities in the psychophysical luminance channel. As a result, the L- to M-cone ERG and psychophysical ratios can change dramatically at the different states of adaptation. The cone sensitivity thresholds and the L- to M-cone sensitivity ratio in the psychophysical chromatic channel are about unity at all states of adaptation, suggesting the presence of a compensatory mechanism. In dichromats, the responses and sensitivities to stimulation of the absent cone type were generally small at all states of adaptation. But, with reddish backgrounds residual ERG responses and residual psychophysical sensitivities were observed, indicating the presence of either a robust rod driven signal or an additional adaptation mechanisms that are not cone driven and that have not been described before.