Sonic sunglasses (Shadow World)

The sonic sunglasses were a device a copy of the Twelfth Doctor used in the illusion created by the Monks.

Like the real world counterpart, these sonic sunglasses would upload information directly to the Doctor's brain, allowing him to maintain at least some degree of independence and hide the fact that he could no longer see. Despite them being a false creation, these sunglasses could still contact the real world beyond the simulation, with the illusion of the Twelfth Doctor able to send the email Extremis, containing everything he had experienced for the last few hours of the illusion directly to the real sonic sunglasses to warn his real self about the Monk's planned invasion of Earth. (TV: Extremis)