Retinal Implants The article I researched is “Will Retinal Implants Restore Vision?” by Eberhart Zrenner. In this article the author begins by discussing the vision process. It begins with light passing through the pupil. Next the light is focused onto the rods and cones on the outer layer of the retina by the lens. Once this happens the image is transformed into both chemical and electrical signals. The electrical signals are carried from the retina, by ganglion neurons, into the optic nerve. The axons of these ganglion neurons are what form the optic nerve. Finally the information is transferred from the optic nerve to the primary visual cortex, which is a part of the brain. The retina is considered the neuroprocessor of the eye and is responsible for the recognition of images. The article continues next stating that there are many different groups of researchers who are creating types of implants to possibly help the vision of patients with retinas that are degenerating. The author discusses, in great detail, one type is known as an electrical implant. These implants are able to connect right onto the retina. Zrenner states that when electrical implants were used in animal experiments, they have shown positive results. There is, however, a great deal of future research and experiments that must take place before they are used for humans. (Zrenner, 2002) The article goes on to discuss the two types of retinal implants that are being developed. These types are subretinal and epiretinal. The article next describes the difference between the two implants. When the subretinal is implanted, it is placed between the pigment epithelial layer of the retina and the outer layer of the retina. Zrenner explains that this implant is made up of light-sensitive microphotodiodes that contain microelectrodes. These parts are put together on a very tiny and thin plate. He continues by describing how the photodiodes trigger the microelectrodes when the retina is exposed to light. This causes the retinal sensory neurons to be stimulated. The epiretinal implant, on the other hand, is placed on the innermost layer of the retina. In this layer you will find ganglion cells. Zrenner states that this type of implant is a chip that is used to receive electrical signals. He says that these signals come from an outside camera and processing unit and are paired with not only the ganglion cells, but the axons of the cells as well. The implant receives these electronic signals and transfers them from the axons on the ganglion cells to the axons on the optic nerve. From there the images are sent to the brain. (Zrenner, 2002). This article contains a large amount of information about retinal implants, and goes into great detail about it. I believe that the article is very credible. By reading this one can learn about the different parts of the eye and what these parts are responsible for. The article discusses the large amount of research and experiments pertaining to retinal implants. Some of this information is very in depth and can be slightly confusing to interpret. These confusing parts, however, are good because they help you to learn new terms. Learning these terms helps you translate the idea in a way that becomes clearer to you. In my opinion I feel that it is a good source for someone who would like to learn more about this interesting topic. It is, however an older article, and I assume that there is a great deal of more up-to-date information about this topic available.

Reference
Zrenner, E. (2002). Will retinal implants restore vision? Science, 295(5557), 1022-5. Retrieved from http://search.proquest.com/docview/213598549?accountid=27655