M. R. Lessel

Intraoperative retinal light damage reflected in electrophysiologic data

In a series of 30 unilaterally pseudophakic patients, electroretinograms and electrooculograms were recorded 6 months postoperatively. The unoperated on fellow eyes served as controls High intraoperative retinal light exposure (3.4–7.3 mW/cm2, Zeiss OPMI 6 operating microscope) caused a substantial reduction of electrophysiologic potentials. Light protection prevented deterioration of electroretinogram and electro-oculogram potentials; reducing the bulb voltage, tilting the axis of illumination, filtering short wavelengths and the use of light shields resulted in 4-log-unit lower intensities (0.8–3.7 μW/cm2).

The influence of intravitreously injected silicone oil on electrophysiological potentials of the eye

In a prospective study the effect of silicone oil injected in the vitreous cavity was monitored electrophysiologically in six patients who were treated for retinal detachment. Electroretinograms (ERG) and electrooculograms (EOG) were recorded before, shortly after, and up to four months following the removal of the oil. An evident increase of the standing potential could be observed in all eyes after removal of the silicone oil. In some patients the ERG amplitudes increased also. No fast oscillations and virtually no slow oscillations could be recorded in the EOG. Follow-up studies did not show a significant recovery of the bioelectric activity. Intravitreal silicone oil appears to cause an insulation effect which interferes with the propagation of electrical potentials. The result of the present study do not provide information concerning possible retinotoxic effects of silicone oil.

ERG and EOG in progressive paravenous retinochoroidal atrophy.

A case of paravenous retinochoroidal atrophy was followed over a period of more than 2 years. Rapid progression of the disease was reflected in the deterioration of visual acuity and fields. Electroretinographic recordings revealed reduced photopic and scotopic amplitudes according to the extent of the retinal lesions. In electro-oculography virtually no slow and no fast light-induced oscillations could be recorded. These results suggest an involvement of the entire retinal pigment epithelium.

The Fast Oscillation of the Electro- Oculogram

The dependence of amplitudes and peak latencies of the light-induced fast EOG oscillation was studied using rectangular light stimulation. A linear increase of the amplitude was observed in the intensity range tested (24–3,000 asb). No influence of the time of preadaptation to darkness on the amplitudes could be proven in a range of 20 s to 21 min. The peak latency was not dependent on light intensity. Prolonged peak latencies were observed following short and long periods of dark adaptation.

The slow electrooculogram oscillation in malignant choroidal melanoma

Electrooculographic recordings were performed in a series of patients with malignant choroidal melanoma. The amplitudes of the light peaks were reduced in all cases compared with the recordings of the normal fellow eyes. The amount of reduction of the light peaks appeared to be dependent on localization of the tumor. The electrooculograms of eyes with tumors of the posterior pole were found to be reduced significantly. Eyes with malignant melanomas located in the peripheral fundus displayed minor reductions.

Light induced oscillations of the standing potential in achromatopsia

In three children with achromatopsia light-induced oscillations of the standing potential and electroretinograms (ERGs) were recorded. A low drift direct current recording system was applied to monitor the changes of the standing potential under general anesthesia. In all children the scotopic ERG components were normal. No photopic components could be observed. The fast oscillations of the standing potential were normal under scotopic and photopic conditions. The light-induced slow increase of the standing potential displayed low amplitudes and normal peak latencies. The results of our study support earlier investigations suggesting that cone-mediated mechanisms in the retina contribute a significant component to the amplitude of the light peak in the electroretinogram.

Comparison of electro-oculogram recording methods.

The purpose of this study was to compare the variability of the amplitude ratios and latencies of the electro-oculogram (EOG) light peak (LP) in three different recording conditions: Arden ratio (dark trough (DT): 12 min), modified Arden ratio (DT: 15 min) and light peak/dark baseline ratio (LP/BL: 35 min of dark adaptation). Additionally, EOGs from eyes with dilated and undilated pupils were recorded. The light intensity stimulating the eyes with dilated pupils was attenuated 1 log unit. The EOG amplitude ratios displayed no significant difference between the three conditions tested. The comparison of implicit times (time from onset of light exposure to LP) revealed significantly (p < 0.001) shorter values when the recording of the LP was preceded by a dark adaptation of 35 min. The broadening of the curves in DT/LP recordings might be caused by a superposition of a residual dark oscillation on the LP. The recordings from eyes with dilated pupils--stimulated with 1 log unit lower intensity--revealed lower amplitude ratios than the recordings from eyes with undilated pupils.

Ischemic Retinopathy: Reduced Light Peak-and Dark Trough Amplitudes in Electrooculography

In 10 adult subjects with occlusion of the central retinal artery and in 2 children with surgically transsected retinal artery, the standing potential as well as the light peak and dark through were found to be reduced.

Prostacyclins in Diabetes: An Electrophysiological Study

Twelve patients with juvenile (insulin-dependent, type I) diabetes were treated either with prostacyclins or placebo in a double-masked randomized study. The electroretinogram (ERG) was recorded before, 1 day and 8 months after treatment. An analysis of variance and covariance was carried out to evaluate possible treatment or time effects on the a and b waves and the oscillatory potentials of the ERG. Mean values of potentials displayed a decrease of amplitude and an increase of latency over the follow-up period in all patients. No statistically significant difference between treated and placebo groups could be proven.

The dark trough in clinical electro-oculography. Influence of preadaptation on amplitudes and latencies.

The influence of four different intensities of the preadapting light on amplitude and implicit time of the dark-induced oscillation (dark trough) of the electro-oculogram was tested in 10 healthy individuals. The amplitude of the dark trough (normalized to preadapting baseline) was found to be dependent on the intensity of the preadapting light (analysis of variance:p < 0.0001). No correlation could be proven between preadapting light intensity and the implicit time of the dark trough (p = 0.299). The confidence intervals of the implicit time of the dark trough exceeded 14 minutes in all four intensity settings. There was no significant dependence of the absolute baseline values on preadapting intensities (p = 0.236).