Retinal implant
Encyclopedia
A retinal implant is a biomedical
implant
technology currently being developed by a number of private companies and research institutions worldwide. The implant is meant to partially restore useful vision to people who have lost theirs due to degenerative eye conditions such as retinitis pigmentosa
or macular degeneration
. The technology, while still rudimentary, would allow the user to see a scoreboard
type image made up of bright points of light viewed from about arm's length.
There are two types of retinal implants currently showing promise in clinical trials:
Epiretinal Implants (on the retina
) and Subretinal Implants (behind the retina).
Epiretinal Implants sit on top of the retina, directly stimulating ganglia using signals sent from the external camera and power sent from an external transmitter, where Subretinal Implants sit under the retina, stimulating bipolar or ganglion cells from underneath. Subretinal Implants generate signals directly from the incoming light. Some Subretinal Implants use power from external circuitry, while others use only incident light as a power source and effectively replace damaged photoreceptors leaving all other structures within the eye untouched.
However, due to a lack of an external power source, the image signal in this second type of subretinal implant may not be as strong as that given by an externally powered epiretinal or subretinal implant.
Biomedical engineering
Biomedical Engineering is the application of engineering principles and design concepts to medicine and biology. This field seeks to close the gap between engineering and medicine: It combines the design and problem solving skills of engineering with medical and biological sciences to improve...
implant
Prosthesis
In medicine, a prosthesis, prosthetic, or prosthetic limb is an artificial device extension that replaces a missing body part. It is part of the field of biomechatronics, the science of using mechanical devices with human muscle, skeleton, and nervous systems to assist or enhance motor control...
technology currently being developed by a number of private companies and research institutions worldwide. The implant is meant to partially restore useful vision to people who have lost theirs due to degenerative eye conditions such as retinitis pigmentosa
Retinitis pigmentosa
Retinitis pigmentosa is a group of genetic eye conditions that leads to incurable blindness. In the progression of symptoms for RP, night blindness generally precedes tunnel vision by years or even decades. Many people with RP do not become legally blind until their 40s or 50s and retain some...
or macular degeneration
Macular degeneration
Age-related macular degeneration is a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults...
. The technology, while still rudimentary, would allow the user to see a scoreboard
Scoreboard
A scoreboard is a large board for publicly displaying the score in a game or match. Most levels of sport from high school and above use at least one scoreboard for keeping score, measuring time, and displaying statistics. Scoreboards in the past used a mechanical clock and numeral cards to...
type image made up of bright points of light viewed from about arm's length.
There are two types of retinal implants currently showing promise in clinical trials:
Epiretinal Implants (on the retina
Retina
The vertebrate retina is a light-sensitive tissue lining the inner surface of the eye. The optics of the eye create an image of the visual world on the retina, which serves much the same function as the film in a camera. Light striking the retina initiates a cascade of chemical and electrical...
) and Subretinal Implants (behind the retina).
Epiretinal Implants sit on top of the retina, directly stimulating ganglia using signals sent from the external camera and power sent from an external transmitter, where Subretinal Implants sit under the retina, stimulating bipolar or ganglion cells from underneath. Subretinal Implants generate signals directly from the incoming light. Some Subretinal Implants use power from external circuitry, while others use only incident light as a power source and effectively replace damaged photoreceptors leaving all other structures within the eye untouched.
However, due to a lack of an external power source, the image signal in this second type of subretinal implant may not be as strong as that given by an externally powered epiretinal or subretinal implant.