We recorded the electrophysiological findings of three patients with toluene dependency who developed visual disturbance. In five of six eyes the peak latency of the pattern visual evoked cortical potential was prolonged as compared with that of normal subjects. The amplitude and the latency of the a-wave of the electroretinogram were decreased in five of the six eyes and prolonged in four. Those of the b-wave in patients were less affected than the a-wave: in one of six eyes the amplitude of the b-wave was decreased and in two the b-wave latency was prolonged. The amplitudes of the oscillatory potentials were decreased in three of six eyes. The electroretinogram was investigated in one patient and showed little increase in amplitude during light stimulation, so that a lowered light peak to dark trough ratio was obtained. Our findings suggest that any part of the visual pathway, including the distal part of the retina and retinal pigment epithelium, might be impaired by the chronic inhalation of toluene vapors.

Visually evoked cortical potentials in response to pattern-appearance, -disappearance, and -reversal stimuli were studied in normal subjects and in patients suffering from optic neuritis. It was found in normal subjects that pattern disappearance VECPs were as reliable as the pattern reversal ones. On the other hand, the appearance response showed interindividual differences which made its evaluation rather difficult. The same was true in the records of the patients. Both the mean peak latencies of the disappearance responses and those of the pattern reversal ones were prolonged significantly in optic neuritis, compared with those obtained from normal subjects. We concluded that the peak latencies of the disappearance response could be more confidently used than those of the appearance response for diagnosing optic neuritis.

Pattern reversal visually evoked cortical potentials were recorded from 70 normal volunteers, aged from 4 to 70 years. Eleven reversal frequencies between 1 and 20 rev/sec were presented. The progressive reduction in the amplitude of the P100 component with age for lower frequency ranges was shown up to the age decade of 30-39 years and the temporal tuning curve became a constant pattern after 40 years. However, there was a trend that the maxima of the tuning curve shifted toward lower frequencies with age after 30 years.

No abstract

To evaluate whether the transient pattern electroretinogram reflects accommodation, we studied the amplitudes of the P-N component of transient pattern electroretinograms that were elicited in normal volunteers by reversing the checkerboard pattern. The stimuli were presented at a rate of three-reversals per second at a viewing distance of 20 cm. Each subject wore a lens that corrected for distance vision. The ophthalmic lenses were placed in front of the eye. A +12-diopter lens was used first, followed by lenses in decreasing 1-diopter steps, including minus lenses, until no response was recordable. The P-N amplitude was then plotted against increased accommodative stimulus. The graph showed a rapid increase to around 4 diopters, and then a slow decrease with increasing minus lens power. The gradually decreasing part of the graph became steeper under cycloplegic conditions. The amplitude of accommodative response was defined as the difference in diopters between the lens powers for eliciting an electroretinogram amplitude after cycloplegia was achieved and in the untreated pupil. The amplitude of accommodative response attenuated significantly in those subjects older than 40 years.