Eyepiece

An eyepiece is a cybernetic device replacing one of the eyes of some Borg drones.

A removable component, the Borg eyepiece was capable of detecting a wide visual spectrum as well as providing advanced spacial and geometric perspectives. Some versions emitted low-intensity lasers. 

After Seven of Nine was freed from the Borg Collective in 2374, The Doctor designed an artificial eye to replace her eyepiece.