An endo-optic illuminator has a compartment, a divider within the compartment, and a fiber optic cable in optical communication with the divider and with the light source of a microscope. The fiber optic cable transmits the light through its length. The cable has two ends: a tip and a base. A user then positions the cable to emit light with the tip proximate a patients eye. Opposite the tip, the base connects the cable to the light source. The divider redirects light from the light source into the base of the fiber optic cable and then onward to illuminate its tip. The divider includes a prism, beam splitter, mirror flip, occluder, shutter, and the like. The fiber optic cable transmits light with less than a 10% loss of candlepower along its length. The illuminator replaces a second separate light source currently used by ophthalmologists.