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How Does a Prosthetic Eye Work?

written by: Lashan Clarke • edited by: Anurag Ghosh • updated: 12/18/2010

In the past, when someone lost his eye, he would have to wear a patch to cover the damaged eye. However prosthetic eyes can restore the look of having a real eye. Advancements in bionic eyes have made it possible for blind patients to have partial eyesight.

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    Why Use Prosthetic Eyes?

    The prosthetic eye is used to give eyesight to someone who is blind, or more correctly, visually impaired. The person could have been born without an eye, lost the eye due to cancer or had his natural eye damaged in an accident. Therefore, this technological marvel gives the person, who was unable to see, the ability to have sight again.

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    How the Normal Eye Works?

    One of the main components of the eye is the retina. It is here that the main visual images are gathered by the eye and sent to the brain to be converted into images. The eye and the brain work together to form images using neurons in the eye. The neurons are specialized structures and at least five different types are contained within the retina.

    These five types of neurons are the photoreceptors, ganglion cells, horizontal cells, amacrine cells and the bipolar cells. The photoreceptor cells are further broken down into two specialized structures called the rods and cones. The rods and cones are responsible for catching the light coming into the eyes.

    When a person stares at an object, the light from the object is reflected into the retina. The image is upside down and it travels as an electrical impulse using the neurons in the eye. The neurons run together to form the optic nerve that sends the image to the part of the brain which then interprets what the person is looking at right side up.

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    How a Prosthetic Eye Works?

    The chances of a person to be implanted with a prosthetic eye will depend on the reason why he/she is blind. If the person is born blind, often he might have underdeveloped or damaged connections between the retina and the optic nerve. This will make prosthetic eye implantation quite harder.

    Usually most prosthetic eyes are made up of plastic and the implantation process may take up to 4 hours. The ocularist will make a wax shell of the eye and then fill it in with a substance called alginate to get the proper contours of the eye. The front part of the replacement eye is made by using plastic and hand-painted to match the color and texture of the other eye. Paints and colored pencils are used to give the eye more life-like features.

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    New Developments in Prosthetic Eyes

    One of the latest developments in the field of prosthetic eyes that occurred this year is the creation of a bionic eye. The first country to be successful was Australia, and later another prototype was announced in Germany.

    The bionic eye operates by having a chip placed under the person’s retina. A battery is then attached to the person’s ear. The chip is embedded inside the retina and will function and light the neurons or rods and cones photoreceptors. Therefore it allows an eye, which is still in place but blind, to be modified to detect images. At the moment the images viewed are blurry, but people who were blind previously can now see.