Thanks to tiny technology, victims of retitinitis pigmentosa (RP) and age-related macular degeneration (AMD) may be able to
see again someday. The Food and Drug Administration has
approved clinical trials of the Argus II Retinal Prosthesis System,
which is the next phase of a collaboration between the University
of Southern California Doheny Eye Institute, Second Sight Medical Products, and the Department of Energy.
Diseases like RP and AMD attack the retina's photoreceptor
cells, which then degenerate and fail to capture and process
light. The technology comprises a camera and microprocessor
mounted in eyeglasses, a receiver implanted behind the ear, and
an electrode-studded array that's attached to the retina. The
array takes the place of the damaged photoreceptors.
The camera sends images to the microprocessor, which transmits a signal to the receiver. Using a tiny cable, the receiver sends
the signal to the array, which then emits pulses that travel along the optic nerve to the brain. The brain perceives patterns of light
and dark spots corresponding to the stimulated electrodes.
USC and Second Sight tested the first-generation Argus 16,
with an array of 16 electrodes, on six patients. All of the patients
now can detect light, count discrete items, locate and differentiate objects in their environment, and even perceive motion. The
Argus II's 60-electrode array should offer better resolution.
Already, work is under way on a model that will be a fraction
the size of the current devices yet include up to 200 electrodes.
Such a device must be biocompatible with delicate eye tissue yet
able to withstand the eye's corrosive, salty environment. It also
must stay attached to the retina without compressing or pulling
the tissue. And, it needs to draw enough power to function without generating the kind of heat that would damage what remains
of the retina. The DoE has enlisted its member labs to solve
these challenges.
