An ocular printer recorded the patterns of a being's eyes. In 0 ABY the Galactic Empire used a genetically modified form of Bledsoe's disease to cause discolorations in a being's eyes that acted as star charts, revealing hidden Rebel bases. Doctor Kaaldar of the Imperial garrison base on Tatooine used an ocular printer to record these patterns. According to Kaaldar, the process requires that the eyes are open long enough to record the star chart, and was both painless and very quick.