- "The Oculus's existence is known only to the High Council, including its greatest secret: the Oculus not only gives us a window into time, but the ability to shape it as we see fit."
- —Time Master Zaman Druce[src]
The Oculus was a complex device, used by the Time Masters to predict the "true" timeline, and manipulate the events outside of the Vanishing Point, creating an illusion that every single action of those beyond the Vanishing Point was predestined to happen.
The Oculus was a complex device located in the Oculus Wellspring, described by Gideon as located "at the far side of the Vanishing Point". Aside from the device itself, surrounded by a literal wellspring of green energy, Oculus Wellspring included a number of structures, connected to the headquarters of the Time Masters. According to Professor Stein, the Oculus was essentially a massive, temporal computer powered by a scaled-down supernova, the source of the green energy cascades surrounding it.
The connection to the Oculus allowed anybody who used the Oculus Viewing Chamber to see the events as they were "predestined" to happen. According to Time Master Zaman Druce this allowed the time traveling organization to predict and control every action of Rip Hunter's team, including Rip Hunter's own rebellion against the order. However, it seemed that the Time Masters had to take careful steps in ensuring that the "true" timeline would happen, as Druce had to specifically order Vandal Savage to kill Rip Hunter's family. Oculus also "predicted" Ray Palmer's death in the Vanishing Point, although it supposedly could not affect the Vanishing Point at all, and, due to the choices of Mick Rory and Leonard Snart, Ray's death was averted.
After incarcerating the members of Rip Hunter's team at the Vanishing Point, Druce decided to make sure that Rip Hunter understands the Time Masters' reasons for supporting Vandal Savage before the execution. Druce claimed that the Time Masters manipulated every single action of Rip Hunter thanks to the Oculus device, "knowing" that he would never defeat Vandal Savage. The reason for supporting Savage was the invasion of Earth by an alien race, the Thanagarians, that the Time Masters observed happening in 2175. According to Druce, the only timeline where the planet would be saved from the aliens was the one where Vandal Savage has taken over the world, uniting it to stand as one against the invaders. Using the Oculus, the Time Masters manipulated different events throughout the timeline to ensure this outcome.
After Leonard Snart, Sara Lance and Mick Rory freed their teammates from captivity, they have formulated a plan to sabotage Oculus, "cutting off their puppet strings" and ensuring that the Time Masters won't be able to further manipulate timeline in favor of Vandal Savage. The team's mission was successful, as the incoming explosion destroyed the Oculus device, along with many of the structures around it in the Vanishing Point, though at the cost of Snart's life. A surviving Time Master informed Savage that the Oculus' destruction had unmoored time itself, thus ensuring that the Thanagarian invasion may or may not happen as well as the Time Masters' alterations to the timeline having been undone.