Abstract: A test to diagnose, monitor or stratify diseases directly or indirectly associated with cholin ergic system pathologies, including Parkinson's disease, which involves a comparison of supplied pupil light reflex data against known normative data of the same kind, characterised by the fact that the supplied data contain the pupil light reflex data, which include at least one sample comprising at least one supplied parameter measured by a known device used to measure pupil light reflexes, and data which include at least one characteristic of the examined patient. The probability of disease occurrence is determined using machine learning algorithms, which comprise at least one neuronal network algorithm (SSN) and/or at least one mathematical function which is not a part of the neuronal network (SSN).