Faculty of Life Sciences, School of Optometry and Vision Science, Bar-Ilan University, Ramat Gan, Israel.
Bar-Ilan Institute for Nanotechnology and Advanced Materials (BINA), Bar-Ilan University, Ramat Gan, Israel.
J Neural Eng. 2021 Mar 3;18(2). doi: 10.1088/1741-2552/abdd42.
Restoration of central vision loss in patients with age-related macular degeneration (AMD) by implanting a retinal prosthesis is associated with an intriguing situation wherein the central prosthetic vision co-exists with natural normal vision. Of major interest are the interactions between the prosthetic and natural vision. Here we studied the effect of the light-adaptive state of the normal retina on the electrical visual evoked potentials (VEPs) arising from the retinal prosthesis.We recorded electrical VEP elicited by prosthetic retinal stimulation in wild-type rats implanted with a 1 mm photovoltaic subretinal array. Cortical responses were recorded following overnight dark adaption and compared to those recorded following bleaching of the retina by light (520 nm) at various intensities and durations.Compared to dark-adapted responses, bleaching induced a 2-fold decrease in the prosthetic cortical response, which returned to the dark-adapted baseline within 30 min to several hours, depending on the degree of bleaching. This reduction was neither observed in Royal College of Surgeons (RCS) rats with a degenerated photoreceptor layer nor following intravitreal injection of a GABAa receptor blocker (bicuculine), suggesting the involvement of photoreceptors and a GABAa-mediated mechanism.These findings show a robust effect of the retinal light-adaptive state on the obtained prosthetic responses. If a similar effect is found in humans, this will have immediate implications on the design of prosthetic devices, where both natural and prosthetic vision co-exist, such as in AMD patients receiving a photovoltaic retinal implant. Similarly, standardization of the retinal light-adaptive state in prosthetic clinical trials should be considered.
恢复与年龄相关的黄斑变性（AMD）患者的中央视力丧失通过植入视网膜假体与一个有趣的情况相关联，其中中央假体视力与自然正常视力共存。主要感兴趣的是假体和自然视力之间的相互作用。在这里，我们研究了正常视网膜的光适应状态对来自视网膜假体的电视觉诱发电位（VEPs）的影响。我们记录了植入 1 毫米光伏子视网膜阵列的野生型大鼠的假体视网膜刺激引起的电 VEP。在过夜暗适应后记录皮质反应，并将其与在不同强度和持续时间下用光（520nm）漂白视网膜后记录的反应进行比较。与暗适应反应相比，漂白诱导假体皮质反应降低了 2 倍，该反应在 30 分钟至数小时内恢复到暗适应基线，具体取决于漂白的程度。在具有退化的光感受器层的皇家外科学院（RCS）大鼠中或在玻璃体内注射 GABAa 受体阻滞剂（bicuculine）后均未观察到这种降低，表明光感受器和 GABAa 介导的机制的参与。这些发现表明视网膜光适应状态对获得的假体反应有很强的影响。如果在人类中发现类似的效果，这将对同时存在自然和假体视力的假体设备的设计产生直接影响，例如在接受光伏视网膜植入物的 AMD 患者中。同样，应考虑在假体临床试验中标准化视网膜的光适应状态。
