3D electronic implants in subretinal space : long-term follow-up in rodents

Photovoltaic subretinal prosthesis (PRIMA) enables restoration of sight via electrical stimulation of the interneurons in degenerated retina, with resolution limited by the 100 μm pixel size. Since decreasing the pixel size below 75 μm in the current bipolar geometry is impossible, we explore the possibility of using smaller pixels based on a novel 3-dimensional honeycomb-shaped design. We assessed the long-term biocompatibility and stability of these arrays in rats by investigating the anatomical integration of the retina with flat and 3D implants and response to electrical stimulation over lifetime – up to 9 months post-implantation in aged rats. With both flat and 3D implants, VEP amplitude decreased after the day of implantation by more than 3-fold, and gradually recovered over about 3 months. With 25 μm high honeycomb walls, the majority of bipolar cells migrate into the wells, while amacrine and ganglion cells remain above the cavities, which is essential for selective network-mediated stimulation of the second-order neurons. Retinal thickness and full-field stimulation threshold with 40 μm-wide honeycomb pixels were comparable to those with planar devices – 0.05 mW/mm2 with 10ms pulses. However, fewer cells from the inner nuclear layer migrated into the 20 μm-wide wells, and stimulation threshold increased over 5 months, before stabilizing at about 0.08 mW/mm2. Such threshold is significantly lower than 1.8 mW/mm2 with a previous design of flat bipolar pixels, confirming the promise of the 3D honeycomb-based approach to high resolution subretinal prosthesis.Competing Interest StatementDaniel Palanker and Ted Kamins- consultant (Pixium Vision) Daniel Palanker - Patent (Stanford University and Pixium Vision

Enhancing prosthetic vision by upgrade of a subretinal photovoltaic implant in situ

In patients with atrophic age-related macular degeneration, subretinal photovoltaic implant (PRIMA) provided visual acuity up to 20/440, matching its 100μm pixels size. Next-generation implants with smaller pixels should significantly improve the acuity. This study in rats evaluates removal of a subretinal implant, replacement with a newer device, and the resulting grating acuity in-vivo. Six weeks after the initial implantation with planar and 3-dimensional devices, the retina was re-detached, and the devices were successfully removed. Histology demonstrated a preserved inner nuclear layer. Re-implantation of new devices into the same location demonstrated retinal re-attachment to a new implant. New devices with 22μm pixels increased the grating acuity from the 100μm capability of PRIMA implants to 28μm, reaching the limit of natural resolution in rats. Reimplanted devices exhibited the same stimulation threshold as for the first implantation of the same implants in a control group. This study demonstrates the feasibility of safely upgrading the subretinal photovoltaic implants to improve prosthetic visual acuity

Enhancing prosthetic vision by upgrade of a subretinal photovoltaic implant in situ

In patients with atrophic age-related macular degeneration, subretinal photovoltaic implant (PRIMA) provided visual acuity up to 20/440, matching its 100 µm pixels size. Next-generation implants with smaller pixels should significantly improve the acuity. This study in rats evaluates removal of a subretinal implant, replacement with a newer device, and the resulting grating acuity in-vivo. Six weeks after the initial implantation with planar and 3-dimensional devices, the retina was re-detached, and the devices were successfully removed. Histology demonstrated a preserved inner nuclear layer. Re-implantation of new devices into the same location demonstrated retinal re-attachment to a new implant. New devices with 22 µm pixels increased the grating acuity from the 100 µm capability of PRIMA implants to 28 µm, reaching the limit of natural resolution in rats. Reimplanted devices exhibited the same stimulation threshold as for the first implantation of the same implants in a control group. This study demonstrates the feasibility of safely upgrading the subretinal photovoltaic implants to improve prosthetic visual acuity. [Abstract copyright: © 2025. The Author(s).

Conflict resolution in the 3 southern border provinces of Thailand : policy process and outcomes

Thesis (D.P.A.)--National Institute of Development Administration, 2016The roots of the problem of insurgency and violence in the 3 southern border provinces of Thailand, which occurred 11 years ago, are deeply seated in the areas and have affected every aspect of society. Therefore, this study is intended for an overview of the conflict resolution: policy, process and outcomes. The objectives of this study are to analyze 1) the development of the unrest situation from the past to the present 2) the development of policies to tackle the unrest in the 3 southern border provinces 3) the policy implementation process by considering the role of the main agencies that respond to the conflict resolution in the 3 southern border provinces 4) the policy implementation outcomes 5) the key factors that affected the policy implementation outcomes and 6) the remaining problems and obstacles. This study is a qualitative research, employing several research methods, including documentary research, in-depth interviews and focus group discussions by providing keyinformants. Then, the data were analyzed in descriptive analysis for its description.In this study, relevant academic papers conducted by Thai researchers as well as oversea scholars on the unrest in the 3 southern border provinces were reviewed as well as the lessons from Thailand , China, Indonesia and the Philippines. The lessons learnt and experiences from the conflict resolutions, the results of the action plan of the agency, the Southern Border Provinces Administrative Center (SBPAC) and the in-depth interviews of Executives and Head of Operations were compared and evaluated. To find the factors that resulted in policy implementation outcomes, the Pressman and Wildavsky model is synthesized and a new concept is designed called the NIDA Deep South Model to fit the context and security policy in the 3 southern border provinces.To solve the conflict in the 3 southern border provinces it is necessary to have the support through organization competency such as adequacy of resources, quality of personnel, good leadership and motivation that contributes to the factor of communication in the policy process at all levels in order to make the communication process more efficient. These factors must be supported as they can affect the policymaking which is essential to the agencies that cooperate with the other agencies. The complexity of joint action requires organization competency in order to coordinate with the other agencies as well as to have the ability to solve the lag in project problems that occur including the following factors: value, feeling management and popularity factor of urban areas.The authority should have a powerful role in shaping the discourse such as the peace dialogue process discourse and the Tung Yang Dang Model, to solve the problems in the 3 southern border provinces, to cause rapid, continuous and concrete impacts