FDA approves first retinal implant for adults with rare genetic eye diseaseThe U.S. Food and Drug Administration today approved the Argus II Retinal Prosthesis System, the first implanted device to treat adult patients with advanced retinitis pigmentosa (RP). The device, which includes a small video camera, transmitter mounted on a pair of eyeglasses, video processing unit (VPU) and an implanted retinal prosthesis (artificial retina), replaces the function of degenerated cells in the retina (a membrane inside the eye) and may improve a patient’s ability to perceive images and movement. The VPU transforms images from the video camera into electronic data that is wirelessly transmitted to the retinal prosthesis.RP is a rare genetic eye condition that damages the light-sensitive cells that line the retina. In a healthy eye, these cells change light rays into electrical impulses and send them through the optic nerve to the area of the brain that assembles the impulses into an image. In people with RP, the light-sensitive cells slowly degenerate resulting in gradual loss of side vision and night vision, and later of central vision. The condition can lead to blindness.The retina lines the back of the eye’s inner surface and records images in patterns of light and color. The Argus II implant actually relies on a mini camera mounted on a pair of sunglasses to capture an image and send the information to a video processor, worn on the belt along with a wireless microprocessor and battery pack. After the video processor converts the images to an electronic signal, a transmitter on the glasses sends that information wirelessly to the receiver implanted under the eyeball’s clear mucus membrane, called the conjunctiva. The receiver in turn conveys the signals through a tiny cable to an electrode array placed on the retina. The array directly stimulates the cells that lead to the optic nerve.On receiving the pulses, the brain perceives patterns of light and dark spots corresponding to the electrodes stimulated. Patients learn to interpret the visual patterns produced into meaningful images.
Second Sight Medical Products, Inc., is the manufacturer and is already approved in Europe
Argus II components (credit: FDA)
The Argus II design consists of an external video camera system matched to the implanted retinal stimulator, which contains a microelectrode array that spans 20 degrees of visual field.
An external camera system, built into a pair of glasses, streams video to a belt-worn computer, which converts the video into stimulus commands for the implant.
The belt-worn video processing unit (computer) encodes the commands into a wireless signal that is transmitted to the implant, which has the necessary electronics to receive and decode both wireless power and data.
Artificial retina device, consisting of a glasses-mounted camera and a microchip surgically implanted on the retina
Based on those data, the implant stimulates the retina with small electrical pulses. The electronics are hermetically packaged and the electrical stimulus is delivered to the retina via a microelectrode array.