We recorded corneal ERGs from the cat, monkey and human using Ganzfeld stimuli and compared the characteristics of the STR and PII among species. The STR of all three species was a graded corneal-negative potential with similar waveform, maximum amplitude, dynamic range and relationship to rod PII. The STR dominated the ERG for 2.5 log units above threshold. Both the STR amplitude and latency were linear functions of log intensity. The only substantive difference between species was a faster STR latency for the cat than for the monkey and human. The lowest stimulus intensity to observe the corneal STR (i.e. the 'threshold') was approximately 1 quanta (507 nm) per 245 rods for human and per 122 rods for cat, averaged across the retina. Wavelets were superimposed on the STR for stimulus intensities near PII threshold, particularly for the monkey but also for the cat. These may be analogous to oscillatory potentials. PII threshold was about 2.5 log units above STR threshold. For these species the PII amplitude showed a sigmoidal relationship to log intensity and saturated near 0.3 log scot. cd/m3 for 80 ms flashes. Like the STR, latency of PII also was faster for the cat than for the monkey and human. These results demonstrated a considerable similarity of the STR and PII of the cat, monkey and human.
|Original language||English (US)|
|Number of pages||9|
|Journal||Clinical Vision Sciences|
|State||Published - 1991|
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