Precision medicine is the future. In all fields of medicine, optimized therapy aims at identifying individuals at risks in order to prevent diseases, to identify specific molecular targets in a specific patient, at a specific time, to administer optimized treatment with less side effects. To achieve this ambitious aim, biomarkers, which should be specific and sensitive predictive indicators of diseases, or of response to treatment or of a state of evolution of the disease, must be identified. The eye offers an easy access organ to collect directly media or tissue, which can serve to identify such markers. This paper summarizes recent advances in the identification of ocular biomarkers of ocular diseases but also of brain diseases.