Optic nerve

An optic nerve was an organ related to sight. Optic nerves could misfire, resulting in temporary or even permanent blindness. (PROSE: The Door into Bedlam)

When one's optic nerve was "tapped", the act would leave behind scars on the supra-orbital ridge, above the eye. (PROSE: War Crimes)

The Half-Face Man burned a dinosaur that appeared in the River Thames, to use its optic nerve to repair the Clockwork Droids' ship, the SS Marie Antoinette. (TV: Deep Breath)