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To clarify the latency of the earliest cortical activity in visual processing, electroretinograms (ERGs) and visual evoked magnetic fields (VEFs) following flash stimulation were recorded simultaneously in six human subjects. Flash stimuli were applied to the right eye and ERGs were recorded from a skin electrode placed on the lower lid. ERGs showed two major deflections in all subjects: an eyelid-negativity around 20 ms and a positivity around 60 ms corresponding to an a- and b-waves, respectively. The mean onset and peak latency of the earliest component of VEFs (37 M) was 30.2 and 36.9 ms, respectively. There was a linear correlation between the peak latency of the a-wave and the onset latency of the 37 M (r=0.90, P=0.011). When a single equivalent current dipole analysis was applied to the 37 M, four out of six subjects showed highly reliable results. The generator of the 37 M was estimated to be located in the striate cortex in all four subjects. Since post-receptoral activities in the retina are expected to start around the peak of the a-wave (20 ms), the early cortical activity, which appears 10 ms later than the a-wave peak, is considered to be the earliest cortical activity following flash stimulation.

We report 4 fullterm newborns who developed retinopathy similar to oxygen-induced retinopathy after high concentration oxygen therapy for pneumothorax and emphysema. Two of them had a severe condition, showing marked dilatation, winding, and abnormal branching of the retinal vessels, especially veins, and retinal trubidity. Comparison between the 4 patients and controls without such retinopathy suggested that factors such as the oxygen concentration, the duration of oxygen therapy, the gradual reduction method, and the high level and changes in PaO2 were involved in the development of the retinopathy. Even in fullterm infants, treatment should be performed with consideration of the possible occurrence of changes in the eye fundus.