Yue Lan, Castillo Johnny, Gonzalez Alejandra Calle, Neitz Jay, Humayun Mark S
Roski Eye Institute, University of Southern California, Los Angeles, California; Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, California.
Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, California.
Ophthalmology. 2021 Mar;128(3):453-462. doi: 10.1016/j.ophtha.2020.08.019. Epub 2020 Aug 25.
Bioelectronic retinal prostheses that stimulate the remaining inner retinal neurons, bypassing degenerated photoreceptors, have been demonstrated to restore some vision in patients blinded by retinitis pigmentosa (RP). These implants encode luminance of the visual scene into electrical stimulation, however, leaving out chromatic information. Yet color plays an important role in visual processing when it comes to recognizing objects and orienting to the environment, especially at low spatial resolution as generated by current retinal prostheses. In this study, we tested the feasibility of partially restoring color perception in blind RP patients, with the aim to provide chromatic information as an extra visual cue.
Case series.
Seven subjects blinded by advanced RP and monocularly fitted with an epiretinal prosthesis.
Frequency-modulated electrical stimulation of retina was tested. Phosphene brightness was controlled by amplitude tuning, and color perception was acquired using the Red, Yellow, Green, and Blue (RYGB) hue and saturation scaling model.
Brightness and color of the electrically elicited visual perception reported by the subjects.
Within the tested parameter space, 5 of 7 subjects perceived chromatic colors along or nearby the blue-yellow axis in color space. Aggregate data obtained from 20 electrodes of the 5 subjects show that an increase of the stimulation frequency from 6 to 120 Hz shifted color perception toward blue/purple despite a significant inter-subject variation in the transition frequency. The correlation between frequency and blue-yellow perception exhibited a good level of consistency over time and spatially matched multi-color perception was possible with simultaneous stimulation of paired electrodes. No obvious correlation was found between blue sensations and array placement or status of visual impairment.
These findings present a strategy for the generation and control of color perception along the blue-yellow axis in blind patients with RP by electrically stimulating the retina. It could transform the current prosthetic vision landscape by leading in a new direction beyond the efforts to improve the visual acuity. This study also offers new insights into the response of our visual system to electrical stimuli in the photoreceptor-less retina that warrant further mechanistic investigation.
生物电子视网膜假体通过刺激剩余的视网膜内层神经元，绕过退化的光感受器，已被证明能使因色素性视网膜炎（RP）而失明的患者恢复部分视力。然而，这些植入物将视觉场景的亮度编码为电刺激，却遗漏了色彩信息。然而，在识别物体和适应环境时，颜色在视觉处理中起着重要作用，尤其是在当前视网膜假体产生的低空间分辨率情况下。在本研究中，我们测试了在患有RP的盲人患者中部分恢复颜色感知的可行性，旨在提供色彩信息作为额外的视觉线索。
病例系列。
7名因晚期RP而失明且单眼植入视网膜假体的受试者。
测试了视网膜的调频电刺激。通过幅度调整来控制光幻视亮度，并使用红、黄、绿、蓝（RYGB）色调和饱和度缩放模型来获取颜色感知。
受试者报告的电诱发视觉感知的亮度和颜色。
在测试的参数空间内，7名受试者中有5名在颜色空间中感知到沿蓝黄轴或其附近的彩色。从这5名受试者的20个电极获得的汇总数据表明，尽管在转换频率上受试者之间存在显著差异，但将刺激频率从6Hz增加到120Hz会使颜色感知向蓝色/紫色偏移。频率与蓝黄感知之间的相关性在时间上表现出良好的一致性，并且通过同时刺激配对电极可以实现空间上匹配的多色感知。在蓝色感觉与阵列位置或视力损害状态之间未发现明显相关性。
这些发现提出了一种通过电刺激视网膜在患有RP的盲人患者中沿蓝黄轴产生和控制颜色感知的策略。它可能会引领一个超越提高视力努力的新方向，从而改变当前的假体视觉格局。本研究还为我们的视觉系统在无感光细胞的视网膜中对电刺激的反应提供了新的见解，值得进一步进行机制研究。
