Artificial Vision

Retinal implants were designed for people with retinal diseases such as retinitis pigmentosa or age-related macular Japan's Mitsubishi Electric presents the first color artificial retina in 1999. © AFP/Corbis. Reproduced by permission. degeneration. These implants rely on intact retinal neurons to transmit the stimuli to the brain. A number of varying designs are being used in clinical trails; the main difference between them is the localization of the implant in the retina. Epiretinal implants are placed on the retinal surface and subretinal implants are placed under the retina.

The first retinal implant to move into clinical trials (in 2000) was a subretinally placed artificial silicon retina (ARS). The ARS is a very small silicon microchip of 2mm in diameter and 25 micrometers thick, composed of miniature solar cells. The arrays of these cells respond to light similar to natural photoreceptors.

The artificial retina component chip (ARCC) is an example of an epiretinal implant. The ARCC is composed of light sensors and electrode arrays that send signals to the retinal neurons. However, the system requires additional power and is dependent upon an external camera to detect a picture and induce a laser pulse. Incoming laser light is detected by the photo sensors in the implant to create a picture. The camera and the laser are build into special sunglasses.

vOICe system was developed as an alternative to surgical implants. Users claim that they are receiving visual sensations from using the system, which involves changing images from a video camera into corresponding sound patterns that in turn, stimulate the visual cortex. The vOICe technology, therefore, can be classified as artificial vision, although only its effectiveness as a sensory substitution has been established. The main advantages are no surgical intervention and cost of the device is only $2,500.