The program starts by generating a cartoon in order to attract the attention of the child. This cartoon is followed by the presentation of a checkerboard with large dimensions. The frequency spectrum of the recorded signal is displayed in real time on the control monitor and allows the operator to visualize the response that is characterized by a peak at the stimulation frequency. The operator can then trigger sweep stimulations that generate a rapid succession of 20 different patterns of decreasing sizes.
The program calculates the vector average of the different sweep responses recorded during the exam. Vector averaging is an efficient way to reduce the noise level and to evaluate the reproducibility of responses. From this vector average, the program automatically determines visual acuity as the smallest size of pattern that produces a response (20/82 in the present example).