Degeneration of photoreceptors in the retina is a leading cause of blindness, but commonly leaves the retinal ganglion cells (RGCs) and/or bipolar cells extant. Consequently, these cells are an attractive target for the invasive electrical implants colloquially known as “bionic eyes.” However, after more than two decades of concerted effort, interfaces based on conventional electrical stimulation approaches have delivered limited efficacy, primarily due to the current spread in retinal tissue, which precludes high-acuity vision. The ideal prosthetic solution would be less invasive, provide single-cell resolution and an ability to differentiate between different cell types. Nanoparticle-mediated approaches can address some of these requirements, with particular attention being directed at light-sensitive nanoparticles that can be accessed via the intrinsic optics of the eye. Here we survey the available known nanoparticle-based optical transduction mechanisms that can be exploited for neuromodulation. We review the rapid progress in the field, together with outstanding challenges that must be addressed to translate these techniques to clinical practice. In particular, successful translation will likely require efficient delivery of nanoparticles to stable and precisely defined locations in the retinal tissues. Therefore, we also emphasize the current literature relating to the pharmacokinetics of nanoparticles in the eye. While considerable challenges remain to be overcome, progress to date shows great potential for nanoparticle-based interfaces to revolutionize the field of visual prostheses.

中文翻译：

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用于视网膜神经调节的基于纳米颗粒的光学接口：综述

视网膜感光细胞退化是导致失明的主要原因，但通常会导致视网膜神经节细胞 (RGC) 和/或双极细胞残存。因此，这些细胞是俗称“仿生眼”的侵入性电植入物的有吸引力的目标。然而，经过二十多年的共同努力，基于传统电刺激方法的界面的功效有限，这主要是由于视网膜组织中的电流扩散，阻碍了高敏锐度视力。理想的假体解决方案侵入性较小，提供单细胞分辨率并能够区分不同细胞类型。纳米颗粒介导的方法可以满足其中一些要求，特别关注可以通过眼睛的固有光学器件访问的光敏纳米颗粒。在这里，我们调查了可用于神经调节的已知的基于纳米颗粒的光学转导机制。我们回顾了该领域的快速进展，以及将这些技术转化为临床实践时必须解决的突出挑战。特别是，成功的翻译可能需要将纳米颗粒有效递送到视网膜组织中稳定且精确定义的位置。因此，我们还强调当前与纳米粒子在眼中的药代动力学相关的文献。尽管仍有相当大的挑战有待克服，但迄今为止的进展表明，基于纳米颗粒的界面具有彻底改变视觉假体领域的巨大潜力。