No abstract

By means of a newly developed method including a suction contact lens and matched calomel half-cell electrodes which were temperature stabilized, the standing potential (SP) of the human eye, considered to be generated mainly in the pigment epithelium, could be directly recorded under stable conditions. Upon a change in illumination from darkness to 16 Lux, an initial, rather fast, negative transient was followed by slower, damped oscillations with a frequency of about 2/hour. The maximum amplitude of an oscillation was of the order of 5mV. When the illumination was changed in the opposite direction, the polarity of the oscillations was reversed into a mirror image of the variations described above. Also, the oscillations now were considerably smaller in amplitude. With respect to phases and frequencies, the results correspond well to the changes found in EOG measurements. The new method seems to permit a study of the effects of drugs and other substances on the human SP, which is also likely to reflect the condition of the pigment epithelium. (Kbh.) Suppl. 73. Yoshida, Y. (1953) On the nature of steady potential of toads eye and adaptation. J . physiol. SOC. Jab. 15, 133-142.

The c-wave and the directly recorded standing potential (SP) of the human eye were studied with the aid of a recently developed method including matched temperature stabilized calomel electrodes, d.c. amplifiers and a suction contact lens. This technique, which does not require general anaesthesia, permits simultaneous direct d.c. recordings of the SP and the c-wave in human volunteers during long-term experiments. Upon repetitive light flashes (stimulus duration 1 sec, interval 20 sec and flash intensity 4.5 rel. log units above b-wave threshold) both variables responded with slow amplitude oscillations with a frequency of about 2/hour. The oscillations were similar as to phases and frequencies. Both the potentials are held to be generated mainly in the pigment epithelium. Considering this partly common origin the observed covariation was an interesting finding.

The amplitude of the c-wave of the human d.c. registered ERG is known to oscillate with a frequency of about 2Jhour in response to repeated stimulations. A small oral dose of ethyl alcohol caused a marked increase in amplitude of the oscillations and also elevated their mean level. A first peak was reached 10-15 min after the intake of alcohol. The b-wave increased slightly in response to ethanol, but no significant effect on the a-wave was observed with the present doses and stimulus conditions. The results encourage further studies of drug influence on the c-wave with the intention of correlating ocular toxicity of a substance to c-wave changes.

Low and moderate i.v. doses of toluene or styrene dissolved in a lipid emulsion (Intralipid) were given to cynomolgus monkeys. The d.c. ERG and the standing potential (SP) of the eye were recorded directly with corneal contact lenses, very stable calomel electrodes and under very constant general anaesthesia. Even small doses of the solvents, corresponding approximately to the Swedish hygienic threshold limit values for these solvents in air, clearly provoked slow variations with time in the amplitude of the c-wave of the ERG and in the SP level. Both potentials are generated mainly in the pigment epithelium. It is suggested that the effects reflect a direct influence of the solvents upon i.a. the cell membrane or the metabolism of the pigment epithelium.