Development Of Retinal Prosthesis Research Articles

A Three-Dimensional Microelectrode Array to Generate Virtual Electrodes for Epiretinal Prosthesis Based on a Modeling Study.

Despite many advances in the development of retinal prostheses, clinical reports show that current retinal prosthesis subjects can only perceive prosthetic vision with poor visual acuity. A possible approach for improving visual acuity is to produce virtual electrodes (VEs) through electric field modulation. Generating controllable and localized VEs is a crucial factor in effectively improving the perceptive resolution of the retinal prostheses. In this paper, we aimed to design a microelectrode array (MEA) that can produce converged and controllable VEs by current steering stimulation strategies. Through computational modeling, we designed a three-dimensional concentric ring-disc MEA and evaluated its performance with different stimulation strategies. Our simulation results showed that electrode-retina distance (ERD) and inter-electrode distance (IED) can dramatically affect the distribution of electric field. Also the converged VEs could be produced when the parameters of the three-dimensional MEA were appropriately set. VE sites can be controlled by manipulating the proportion of current on each adjacent electrode in a current steering group (CSG). In addition, spatial localization of electrical stimulation can be greatly improved under quasi-monopolar (QMP) stimulation. This study may provide support for future application of VEs in epiretinal prosthesis for potentially increasing the visual acuity of prosthetic vision.

Preoperative Candidate Evaluations for Retinal Prosthesis Trials

With the development of retinal prostheses, the first clinical trials for these devices are being planned or are already underway. Yet the candidate selection criteria and the preparation of early recipients have received very little attention. As clinical trials grow in scope, the need for such issues will become increasingly important. Especially in preliminary stages of clinical trials, it is absolutely vital to develop the preoperative evaluations of candidates in identifying the suitable candidate for retinal prosthesis implants. This paper addresses the preoperative evaluations of candidates that may provide insight into selecting potential candidates for retinal prosthetic devices. Screening an ideal candidate is complex and, at the minimum, should include medical evaluations, visual function tests, assessments of psychological status, motivation, expectations, as well as rehabilitation capabilities. This will ensure that appropriate candidates are selected, candidate expectations are managed, and success with the retinal prosthetic devices is maximized.

Novel Interface to Biological Systems for Retinal Prosthetics

AbstractThe development of retinal prostheses requires a method for interconnecting an imaging system to the retina. Such a system must be able to individually address and stimulate retinal neurons, a significant advance from current technology. As a step toward this goal, we present a novel electronic-to-biologic interface using microfabricated apertures in a silicon substrate. Apertures are created in a thin silicon nitride membrane, after which the surface is appropriately modified to support cell growth. Excitable cells are seeded on the device and imaged using Ca2+-sensitive fluorescent dyes in either an inverted or confocal microscope. Using rat pheochromocytoma (PC12) cells, we show the ability to stimulate locally through the apertures. The device allows for the stimulation of cells at precise locations, a necessary requirement for future high-resolution retinal prostheses.