1. A system for the preliminary diagnosis of ocular diseases CHARACTERIZED in that it comprises: a device for capturing images or a camera; a device generating light or a flash; a screen for displaying the image; a memory for storing data; a computational application stored in the memory that executes the process of capturing a plurality of images of the eyes of an individual, and a final corrected image obtained through the processing of said plurality of images, by performing a post-processing of the final image corrected by calculating the percentage of the colors that compose the pupillary reflex of each eye and comparing it with the values obtained for previous clinical cases; and a processor functionally attached to the camera, the flash, the screen and the memory in such a way that it runs the application.