BACKGROUND

[1]

The retina is a layer of tissue that resides in the back of the eye. The retina's purpose is to sense light and send those images to the occipital lobe. The occipital lobe is the visual processing area of the brain. The retina provides the visual groundwork needed for central vision. Damage to the retina or disorders that affect the retina can affect the visual system and can lead to blindness.

Examples of retinal disorders are:

Retinal detachment - a medical emergency, when the retina is pulled away from the back of the eye
Macular pucker - scar tissue on the macula
Macular hole - a small break in the macula that usually happens to people over 60
Floaters - cobwebs or specks in your field of vision [2]

[3]

Retinal diseases vary and some are easily treated while others consist of more complicated scenarios. Symptoms of retinal diseases could include: specks floating in the visual field, to blurred or lost vision. [3] There are several treatment options for mild forms of a retinal disorder. This site is focused on illustrating solutions to severe forms of retinal disease, such as blindness.

Visual prosthetics consist of stimulating several different levels of the visual system to aid individuals who are partially blind or blind. There are three main types of visual prosthetics [4]:

Devices that use a camera to sample the environment of an individual and take that information and transduce it into electrical signals in which a person is able to discern the proximity and shape of objects in the visual field.
Retina enhancers provide the retina with information by stimulating with electrical signals which allow the visual pathway to continue to the brain via the optic nerve.
Digital devices that obtain images of the visual field and breakdown that information into electrical signals that could be used to stimulate the brain directly by inserting or placing electrodes on the surface of the visual cortex.

The goal of retinal electrode implantation is to bypass the layers of degenerated retinal tissue layers and to transfer visual information into the retinal network by direct electrical stimulation. There are different electrode implant designs: epiretinal, subretinal, and external. There are also different anatomical arrangements of implant components: intraocular and extraocular. Although the retina photoreceptors might be lost due to retinal diseases, the inner retina is well preserved [5] and the goal of retinal electrode implantation is to take advantage of this and stimulate the retina to allow an individual to see.