In most species, the eye worked by directing light onto the optic nerve by means of a lens, and was protected by an eyelid designed to remove foreign objects and shade against bright lights. There were many variations, from the subtly degraded night-vision of the local Human population of Hapes, through the night-vision enhancing glowing red eyes of the Chiss, to the multi-faceted eyes of Rodians, the infrared vision of species like the Barabels, the eyes of the Ssi-ruuk with their sensitive retinae and highly-evolved eyelids, and the exotic visual perceptions of the spacegoing Oswaft.
There were also species like the Miraluka, who lost their eyes in the course of their evolution, depending instead on the Force, and the Shaper caste of the Yuuzhan Vong species, who had bred several species of highly sophisticated creatures called mqaaq'it to serve as symbiotic artificial eyes. Yuuzhan Vong had Eye sacks under their eyes.
The photosensitive cilia on the Cloak of the Nuun, another Yuuzhan Vong biot, were perhaps among the most exotic organic eyes known. Tiny membranes covering the creature's entire surface, they saw the immediate area with near-perfect accuracy from every angle, enabling the cloaker to disguise itself, chameleon-like, against its surroundings.