The Visual Cortex 2.0 - The Eye, Redesigned is an eBook in Deus Ex: Human Revolution. It can be found in the Detroit LIMB clinic, on a surgical instruments trolley, between the two operating room doors.
Excerpt from an article by Hugh Darrow in The American Cybernetics Gazette, Winter 2012 Edition.
In the organic model, normal vision begins when light enters through its lens and moves to strike specialized light-receiving photoreceptor cells coating the retina, called rods and cones. These cells convert light into electrochemical impulses that are sent down the optic nerve and into the sense centers of the human brain. In healthy subjects, the eye can function well for many years, but retinal diseases like age-related macular degeneration retinitus pigmentosa destroy vision by annihilating these cellular matrices.
A visual prosthetic - what some colloquially call a "bionic eye" - is a form of neural prosthesis intended to partially restore vision in a patient suffering from one of the aforementioned afflictions, or to amplify and enrich the existing vision of a healthy subject. Darrow Industries' refinement of this technology does away with the need for an external camera-to-implant relay system, instead reducing the extant hardware to a single biochip directly inserted into the retinal zone of the eye.