Optobionic vision—a new genetically enhanced light on retinal prosthesis

Abstract

The recent discovery that neurons can be photostimulated via genetic incorporation of artificial opsins is creating a revolution in the field of neural stimulation. In this paper we show its potential in the field of retinal prosthesis. We show that we need typically 100 mW cm(-2) in instantaneous light intensity on the neuron in order to stimulate action potentials. We also show how this can be reduced down to safe levels in order to negate thermal and photochromic damage to the eye. We also describe a gallium nitride LED light source which is also able to generate patterns of the required intensity in order to transfer reliable images.

Optogenetic therapy for retinitis pigmentosa

“…56 Currently, the sensitivity of optogenetically transduced cells is poor, cells providing photoresponses at high cone ranges. [23][24][25] The number of expressed sensors can be improved, for example, by using strong promoters, high AAV titers and optimal AAV serotypes for a given cell type.…”

“…How much sensitivity is really necessary if an external device is anyway required for adaptation? A practical definition of the minimum sensitivity offered by Degenaar et al 56 is 'the amount of light that is allowed to radiate into the eye by regulatory agencies' . Note that this maximum-allowed radiation is wavelength dependent, in which more radiation is allowed at higher wavelengths.…”

Evolution of optogenetic microdevices

“…23 Despite the high power intensities achievable through laser-based systems, sufficient levels to activate ChR-2 proteins with 470 nm photostimulation are modest, with the minimum spiking irradiance being between 0.1 and 1 mW∕mm 2 (or 10 6 to 10 7 cd∕mm 2 ). 24 At intensities <0.1 mW∕mm 2 , ChR-2 response falls below 10%. 25 High-intensity light sources, such as arc lamps 16,26 and lasers, 15,27,28,29 can achieve these optical outputs, as well as many LEDs; [30][31][32] however, their function is limited to single-point illumination and whole-field illumination.…”

A CMOS-based neural implantable optrode for optogenetic stimulation and electrical recording

“…Such combined gene-therapy and optoelectronics approach to prosthetics could have applications in artificial vision, auditory systems and brain pacemakers [1][2][3][4][5][6]. Previously, we developed CMOS driven µLED arrays for retinal prosthesis [2,5,[7][8][9], and our interests in this work are utilizing our technology to develop brain implants. The key requirements include an ultra-miniature footprint, low power consumption, biocompatibility and stability.…”