1. A method for screening a patient with respect to a plurality of disease states having retinal manifestations, comprising the steps of: providing a CBIR system including an archive of stored digital retinal photography images and diagnosed patient data comprising said retinal photography images, said retinal photography images each indexed in a CBIR database using a plurality of feature vectors, said feature vectors corresponding to distinct descriptive characteristics of said stored images, and said diagnosed patient data further comprising an identification of a presence or an absence of at least one of a plurality of disease states; obtaining current patient data comprising a query image of a retina of the patient; identifying, using image processing, regions or structures in said query image; describing said regions or structures using said plurality of feature vectors; retrieving a population of stored images from said database based at least on a similarity to said regions or structures, and ascertaining, based on at least the current patient data and the CBIR database associated with the diagnosed population, the presence or the absence of a disease having retinal manifestations in said patient, the ascertaining comprising: statistically analyzing of the diagnosed patient data to detect a prevalent one of plurality of disease states in the population, and determining the presence of a disease having retinal manifestations in the patient if a prevalent one of the plurality of disease states is detected, else determining the absence of a disease having retinal manifestations in the patient.