The EOG100C amplifies the corneal-retinal potential. The amplifier monitors the DC potential on the skin surrounding the eyes, which is proportional to the degree of eye movement in any direction. The amplifier output can be switched between normal EOG output and Derivative of EOG. In Derivative mode, the amplifier outputs the measured velocity of eye movement, which is useful for saccade and nystagmus investigations. The amplifier permits DC coupling to electrodes for X/Y graphing of eye movement without discernible decay.