Figure 1: Reaction time perimeter showing the six visual stimulus units (large openings in the aluminum arc) constructed from 3 × 5 LED arrays assembled on a printed circuit board capable of displaying the STS (size Goldmann III) and an arrow head figure (< or >; see the inset picture) for the FO. The small opening in the centre of the aluminum arc is for an ambient light sensor for measuring the intensity of room lighting. The remote control (not in the picture) for reporting the recognition of the fixation object is connected to the perimeter by cable. Data transfer to computer was done after the test using USB cable.