Eye-pod

Eye-pods were the eyes of the Cybermen, which granted them vision. Matching the original humanoid form, the eye-pods numbered two on the faceplate of the Cyber-helmet. (PROSE: Earthshock, The Tenth Planet et al.)

Cybermen of Pete's World were able to establish a visual link, transmitting the vision of their eye-pods to other devices. During the Battle of Canary Wharf, Cyber-Units Ten-Six-Five and Ten-Six-Six opened a visual link connected to a laptop computer within Torchwood Tower, allowing Cyber-Leader One to witness the disastrous confrontation with Dalek Thay and make visual contact with Dalek Sec, meeting the Cult of Skaro's communications barrier. (TV: Doomsday)

Turning against the Cybermen following her upgrade to Cyber-form at Canary Wharf, Yvonne Hartman was seen to shed what appeared to be a tear of oil from her left eye-pod. (TV: Doomsday)

Following her conversion into a Mondasian Cyberman aboard the Mondasian colony ship, Bill Potts appeared to shed a tear, which the Twelfth Doctor found to be a real tear. As it turned out, the tears had been left to Bill by Heather, in the form of the sentient oil. (TV: The Doctor Falls)

The eye-pods of the Cyberdrones, who appeared as disembodied Cyber-heads, gave a blue glow of light as they served as both a means of vision, providing a heads-up-display to pinpoint targets, and an energy weapon, firing blue pulses. (TV: Ascension of the Cybermen)

Behind the scenes
Ascension of the Cybermen featured a smooth transition from the "cold opening" into the title sequence, with the scene going through the eye-pod of a Cyber-helmet.