Eye of the Psion Incarnate (3.5e Equipment)
From D&D Wiki
This orb of green crystal is the exact size of a medium creature's eye.
The Eye of the Psion Incarnate is useful only to Psionic characters. It replaces one eye and occupies space on the body as magic lenses or goggles. Despite replacing one's eye, one can see through the crystal even better than with the original eye.
The eye grants the wearer darkvision out to 60 feet (or improves any other darkvision, no matter the source, by 60 feet). The wearer is also utterly immune to gaze attacks, and gains a permanent True Seeing effect. The Wearer may use My Light at will, as well as Ubiquitous Vision and Touchsight 3/day each as a 20th level Psion. In addition, it functions as a Cognizance Crystal and stores up to 17 power points.
Should the bearer ever die, the eye vanishes several minutes later if not yet claimed only to turn up again some centuries later in the tomb of some powerful Psion. If the former bearer is subsequently returned to life, their missing eye is replaced with a fully-functional one, only this one is green and grants 30' darkvision if the creature did not already have it. The Eye of the Psion Incarnate is utterly neutral and may be used by any Psionic character of at least 10th level. Any non-psionic character attempting to use it gains no benefit, and is penalized for missing an eye as normal.
 For the DM
The Eye of the Psion Incarnate can easily be adapted to fit any Psionic or partly-Psionic campaign. However, should it need to be destroyed for any reason, it most likely requires a Level 20 quest involving the lower underdark, a mind flayer psionist, an ancient red dragon, and an ancient sealed rift that opens onto the plane of Limbo. The released psionic and planar energies may possibly unlock epic levels for the PCs as well, and possibly grant them an immediate level up to level 21. Just a thought for if you are looking for a way to expand into epic levels.