
Photovoltaic retinal prosthesis is a technology for restoration of sight to patients blinded by
degenerative retinal diseases, such as
retinitis pigmentosa and
age-related macular degeneration
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, som ...
(AMD), when patients lose the 'image capturing' photoreceptors, but
neurons in the 'image-processing' inner retinal layers are relatively well-preserved.
This subretinal
prosthesis
In medicine, a prosthesis (plural: prostheses; from grc, πρόσθεσις, prósthesis, addition, application, attachment), or a prosthetic implant, is an artificial device that replaces a missing body part, which may be lost through trau ...
is designed to restore sight by electrically stimulating the surviving inner retinal neurons, primarily the bipolar cells. Photovoltaic retinal implants are completely wireless and powered by near-infrared illumination (880 nm) projected from the augmented-reality glasses. Lack of trans-scleral cable greatly simplifies the implantation procedure compared to other retinal implants.
Optical activation of the photovoltaic pixels allows scaling the implants to thousands of electrodes and retains natural coupling of the eye movements to visual perception.
Studies in rats with retinal degeneration demonstrated that prosthetic vision with such subretinal implants preserves many features of natural vision, including flicker fusion at high frequencies (>20 Hz), adaptation to static images, antagonistic center-surround organization and non-linear summation of subunits in receptive fields, providing high spatial resolution.
Clinical trial with the first-generation of such implants
PRIMA Pixium Vision) having 100μm pixels demonstrated that AMD patients perceive letters and other patterns with spatial resolution closely matching the pixel size. Moreover, central prosthetic vision is perceived simultaneously with the remaining natural peripheral vision.

The next-generation implants with 20μm pixels provided grating acuity matching the natural limit of resolution in rats (28μm).
Currently, such high-resolution implants are being optimized for human retina b
a
Stanford University
References
External links
Photovoltaic retinal prosthesis restores high-resolution responses to single-pixel stimulation in blind retinas Blindness equipment
Applications of photovoltaics
{{treatment-stub