What is the Visual Prosthesis?
Despite the inability to convert light into electrical signals because of diseases such as RP and AMD, some communicative function such as the optic nerve can remain in the visual pathway. In this case, artificial stimulation to the visual pathway allows the brain to recognize it as light.
In fact, when receiving a strong blow to the eye or head, we can see the spark for a moment.
This occurs because the brain confuses the blow with light-mediated stimulation. Taking advantages of this phenomenon, the visual prosthesis provides the brain with light perception by applying electrical stimulation directly to the visual pathway through implantable stimulus electrodes. The visual prosthesis is also called the “artificial eye” or the “artificial retina”.
Three Types of Visual Prostheses
Visual prostheses are classified into 3 types depending on where the electrodes are implanted mainly.
A. Retinal Implant
Electrodes are implanted into the eye to stimulate the retina.
B. Optic Nerve Implant
Electrodes are implanted in the optic nerve to stimulate it.
C. Cortical Implant
Electrodes are implanted in the visual cortex to apply electrical stimulation directly to the brain.
Visual Prosthesis of NIDEK
NIDEK continues to promote the national project for the R&D on the Visual Prosthesis in cooperation with several universities. We have developed Japan’s original approach for stimulating the retina called suprachoroidal transretinal stimulation (STS).
In this approach, the scleral pocket is created by making an incision in the sclera, and then a “stimulus electrode array” is placed into it. The array stimulates the retina without direct contact with it.
Intraoperative damage can be minimized by the STS approach compared with other approaches.Additionally, several studies have shown the efficacy of this approach.
For example, semichronic clinical trials revealed that patients with our implant could recognize movements of objects and discern the widths of bars. At present, we are promoting the R&D with evaluating the safety and function toward the clinical application.
The image of STS Method (Movie)
Other Approaches
1. Subretinal Implant
Electrodes are placed under the retina to stimulate it.
2. Epiretinal Implant
Electrodes are placed over the retina to stimulate the bipolar cells or retinal ganglion cells.
3. Suprachoroidal Transretinal Stimulation (STS)
Refer to “Visual Prosthesis of NIDEK”.
4. Optic Nerve Implant
Electrical stimulation is applied to the optic nerve, which connects the retina and the thalamus.
5. Cortical Implant
Electrical stimulation is applied to the visual cortex in the brain.
6. Others
There are other approaches using new technology such as neurotransmitter-based stimulation.
R&D on Visual Prosthesis
