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    Monocular retinal degeneration induced by intravitreal injection of sodium iodate in rabbit eyes
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    Electroretinography
    Erg
    Fundus (uterus)
    Fundus Photography
    In clinical electrophysiology AC-recorded ERGs are used for the investigation of a- and b-wave parameters. The direct coupled (DC-ERG) ist used to record the c-wave. Theoretically the DC-ERG technique has less influence on the recorded potentials than the AC-ERG technique. We recorded AC- and DC-ERGs of 20 normal eyes, 17 eyes with x-linked congenital retinoschisis and 30 eyes with retinal degenerations. In normal eyes no difference was found between AC- und DC-ERG concerning a- and b-wave amplitudes, latencies and implicit times, the b/a-ratios and the oscillatory potentials. The 30 Hz flicker amplitude was higher in the DC-ERG (p less than 0.0003). The intraindividual variability of all measured parameters was comparable between AC- and DC-ERG. In x-linked retinoschisis the b-wave amplitudes and the b/a-ratios were lower in the DC-ERG than in the AC-ERG. In retinal degenerative diseases the a-wave amplitudes were higher and the dark-adapted b-wave amplitudes lower in the DC-ERG, therefore the b/a-ratio was lower in the DC-ERG. We conclude, the DC-ERG is a reproducible method for clinical routine investigations. It is comparable to the conventional AC-ERG technique. In certain diseases the pathological features of the electroretinogram were more distinct in the DC-ERG than the AC-ERG.
    Erg
    Electroretinography
    Retinoschisis
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    Brain-derived neurotrophic factor (BDNF) or normal goat serum (NGS) was injected intravitreously in each 11 wistar albino rats two days before the induction of ischemia. Retinal ischemia was induced in 22 rats by increasing intraocular pressure to the threshold level which extinguished the electroretinography (ERG) b-wave individually, and maintaining for 90 minutes. The ERG b-wave of the BDNF-treated rats recovered to 80.5 +/- 24.4% of their normal amplitude three days after ischemia, while that of the NGS-treated rats recovered only to 11.1 +/- 5.3%. Statistic analysis showed that the recovery level of ERG b-wave after ischemia in the BDNF and NGS treated rats was significantly different (P < 0.01). The results suggest that BDNF could promote the recovery of the retinal electrophysiologic function from ischemia induced by high intraocular pressure.
    Electroretinography
    Erg
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    Acute experimental retinal degeneration was induced in 3-month-old mice with sodium iodate (NaIO3) injection to investigate the effect of bright light with electroretinography (ERG). Eight C 57 black male mice were anesthetized. The ERG was recorded before and 24 h after the injection of NaIO3. Next, only one eye of each mouse was exposed to a bright light of 3.0 x 10(4) lx white light for 30 min. Ten hours later, ERGs of both the light-exposed and the unexposed eye were recorded. The amplitudes and peak latencies of the a wave and b wave were measured. The ERG was recorded as both eyes were exposed to stimulating flashes that were given in an increasing order of 0.6 log unit steps from the dimmest flash to produce a detectable ERG. The ERG from the light-exposed eye showed a distinctly elevated threshold (approx 2.0 log), while the contralateral unexposed eye did not. The peak latencies of both waves were significantly prolonged by exposure to light. In conclusion, light exposure affected ERG thresholds in mice with experimentally induced acute retinal degeneration.
    Erg
    Electroretinography
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    purpose. To detect mice with hereditary retinal impairment, a high-throughput electroretinography (ERG) screening system was established. method. Mice from eight different strains without known retinal disorders (102, 129/SvJ, AKR, C57BL/6J, C57BL/6JIco, CBA/CaJ, and DBA/2NCrlBR) and one control strain with retinal degeneration (C3HeB/FeJ) were fixed on a specially constructed sled, ERG electrodes were placed on the cornea, and mice were moved into a Ganzfeld stimulator. From a luminance range of 0.0125 to 500 cd-s/m2 in a pretest series two levels (5 and 125 cd-s/m2) were chosen to shorten examination times. The root mean square (RMS) of the ERG-recording was analyzed to detect animals with abnormal retinal function. ERG responses of the left and right eyes were compared in amplitudes and implicit times of the a- and b-waves. Statistical analysis of the latter parameters was performed in all wild-type animals. Histology was performed on selected mice. results. ERG recordings of individual animals for the left and right eye revealed good agreement in amplitudes and implicit times of the a- and b-waves (P < 0.05). Comparison of these parameters among the wild-type strains showed several differences. Evaluation of the RMS revealed, in addition to the C3HeB/FeJ mice, a subgroup of mice within the 129/SvJ strain with abnormal retinal function. Molecular analysis of these mice demonstrated the presence of the same retroviral insertion in the Pde6b gene, which is causative of the Pde6b rd1 allele carried in C3HeB/FeJ mice. Histologic analysis demonstrated good correlation between retinal electrophysiology and morphology. conclusions. The present results demonstrate the feasibility of ERG for screening a large number of mice to detect animals with functional retinal impairment.
    Electroretinography
    Citations (56)
    The Electroretinography (ERG) is a noninvasive technique that allows the assessment of functional integrity of the retina. The ERG recordings are biopotencials acquired in the corneal surface as a response of retinal tissue against controlled light stimuli. In clinical ophthalmology ERG is not commonly used but nowadays, because of the high incidence of degenerative diseases of the retina (RD), its use should be increased. Like other biopotentials as electrocardiography (ECG), electroencephalogram (EEG) and electromyography (EMG), ERG is a low amplitude signal, in this case a few hundred of microvolts (µV), which must be fitted and processed. The ERG signals are affected in morphology in the presence of pathologies that affects the integrity of the different retinal cell groups, for example due to some RD. In advanced cases of RD recordings can be abolished in the time domain; and yet in them it is believed that there is relevant clinical information making the ERG a great potential diagnostic tool.
    Erg
    Electroretinography
    Evoked potential