These are defects that human observers cannot see using historically available methods. RAPDx measures very small characteristic differences in pupil responses to novel stimuli. As your doctor we normally look for these differences manually but can only assess one eye at a time in a dimly lit environment, and they are often challenging to see. Viewing both eyes responses together to controlled stimuli in very high detail allows us as doctors to see new detail regarding "Relative Afferent Pupillary Defects" or "RAPD" and other important features that were not measurable before. These responses are recorded over short times to form a "RAPDx Signature™" as a biometric waveform, much like an EKG, but of pupil responses, recording differential responses (amplitudes, latencies, and velocities). Humans can't see this level of detail without a machine vision system.
RAPDx augments the doctor's vision with an automated device to find characteristic pupil response