The c-wave of the ERG in the Cynomolgus Monkey

Abstract

Six adult cynomolgus monkeys were put under general anesthesia and the c-wave of the electroretinogram (ERG) was measured once a week for 4 weeks (twice in the morning and twice in the evening), and individual differences, diurnal variation, and day to day variation were recorded. One adult male was used for the following examination. The monkey was anesthetized and the c-wave of the ERG was recorded successively during dark and light adaptation three times, according to human c-wave conditions. The c-wave time curves were prepared and assessed.

There were considerable individual differences in the c-wave and a striking diurnal as well as day to day variation was evident in the same animal.

Therefore, it is difficult to evaluate the c-wave of the ERG by a one point measurement alone, such as is usually done in routine ERG examinations (the a-wave, the b-wave and the oscillatory potentials). On the other hand, the c-wave time curves during dark adaptation were valley type curves, very similar to those seen in human c-wave time curves prepared on the assumption that the amplitude 12 to 15 minutes after adaptation is the minimum value. Therefore, the time dependent c-wave can serve as an indicator for ophthalmological examination in the cynomolgus monkey as well as humans.