An artificial eye is a prosthesis which is used to replace a missing or damaged eye. There are two types of artificial eyes: ocular and visual prostheses. An ocular prosthesis replicates the missing eye for aesthetic reasons, serving no medical function beyond supporting the eye socket. A visual prosthesis actually provides visual input to the wearer by stimulating the optic nerve, allowing him or her to experience some sight.
Humans have been making ocular prostheses for hundreds of years. The loss of an eye is not terribly uncommon, but it can create an appearance which may be disturbing or frightening to some people. Wearing an ocular prostheses can given someone a normalized appearance, attracting less attention. Inserting a prosthesis into the eye socket will also provide support, reducing the risk of collapse. The loss of one eye will have a profound impact on depth perception, but many people learn to function very effectively with a single eye.
In the mid-20th century, researchers began to explore the idea of creating an artificial eye which could actually see. In order to accomplish the goal of creating a visual prosthesis, scientists had to develop a camera which could interact with the brain by stimulating the optic nerve. This is accomplished by sending electrical signals similar to those which would be sent by a real eye. The brain interprets those signals just like it would if a biological eye was in place.
The science behind the artificial eye is constantly being refined as researchers explore better camera designs and perfect the communication system between the camera and the brain. In the early 21st century, a number of high-functioning artificial eyes had been demonstrated in experimental programs. The development of reliable visual prostheses can make a huge difference to people with severe vision damage or blindness in one or both eyes.
Whether an artificial eye is a visual or ocular prosthesis, it needs to be carefully fitted to the wearer. Everyone's eye sockets are slightly different, and the prosthesis must fit smoothly and comfortably, or it will cause pain, and it could potentially injure the nerves or damage the eye socket. Fitting the prosthesis usually involves multiple sittings of molding and measuring to get as much data as possible about the structure of the eye socket. Once the prosthesis has been created, the patient attends a fitting session and learns how to care for the artificial eye and the eye socket.