July 18, 2012 report
Eye implants make vision-restoring progress
The prosthesis provides electrical stimulation of the retina that can elicit visual perception in blind people with severe to profound retinitis pigmentosa. The system includes an antenna, an electronics case, and electrode array. External equipment includes special glasses, a video processing unit (VPU) and a cable.
The Argus II was designed to bypass damaged photoreceptors altogether. The way the system works is that a video camera in the glasses captures a scene. The video is sent to a small patient-worn computer VPU where it is processed and transformed into instructions sent back to the glasses via a cable. These instructions are transmitted wirelessly to the antenna in the implant. The signals are sent to the electrode array, which emits small pulses of electricity. The pulses bypass the damaged photoreceptors and stimulate the retinas remaining cells, which transmit the visual information along the optic nerve to the brain.
The result delivers greater independence for patients. Users of the Argus II bionic eye say that they can see rough shapes and track the movement of objects; they can slowly read large writing.
Anticipation is high, meanwhile, for a bionic retina that has been designed to restore sight at less cost and with a different technique. The Bio-Retina developed by Nano Retina does not make use of an external camera; instead, a vision-restoring sensor is placed inside the eye, on top of the damaged retina. This is a 24×24-resolution (576-pixel) sensor atop the damaged retina. The device generates a grayscale image.
The implant is inserted through an incision in the eye. The procedure takes 30 minutes and requires only local anesthesia. Bio-Retina transforms naturally received light into an electrical signal that stimulates the neurons, which send the pictures received by Bio-Retina to the brain. A rechargeable, battery-powered mini-laser on a pair of eyeglasses powers the implant wirelessly. After a patient undergoes the procedure, the anticipated recover time is up to one week. Also anticipated is instantaneous restoration of vision, with patients able to distinguish faces and to be able to look from side to side with their eyes rather than needing to turn their heads.
© 2012 Medical Xpress