Characteristics of prosthetic vision in rats with subretinal flat and pillar electrode arrays
Characteristics of prosthetic vision in rats with subretinal flat and pillar electrode arrays
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DOI：
10.1088/1741-2552/ab34b3
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发表时间：
2019-12-01
影响因子：
4
通讯作者：
Palanker, Daniel
中科院分区：
文献类型：
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作者：
Ho, Elton;Lei, Xin;Palanker, Daniel
Objective.视网膜假体旨在通过电刺激幸存的视网膜神经元来恢复视力。在目前视网膜植入物的临床试验中，假体视力不超过20/550。然而，为了在因年龄相关性黄斑变性（AMD）而失明的患者中提供有意义的中心视力恢复，假体视敏度应至少为20/200，需要约50 μ m或更低的像素间距。在这种小像素的情况下，由于电场到组织中的有限穿透，刺激阈值很高。在这里，我们用我们最新的光伏阵列来应对这一挑战，并评估它们的体内性能。Approach.我们制作的光伏阵列与55和40 μ m像素（a）在平面几何形状，和（B）与10 μ m高的支柱上的有源电极。将该阵列植入视网膜变性的大鼠视网膜下。刺激阈值和光栅敏锐度使用视觉诱发电位（VEP）的测量进行了评价。主要结果。与55 μ m的像素，我们测量光栅敏锐度为48 +/- 11 μ m，这匹配的线性像素间距的六边形阵列。这在几何学上对应于人眼中20/192的视敏度，与美国的法律的失明阈值（20/200）匹配。与平面像素相比，使用柱状电极时，辐照度阈值几乎减半，持续时间阈值降低了三倍以上。与40 μ m的像素，VEP是太低的光栅敏锐度的可靠测量，即使与柱电极。意义虽然有助于治疗视力完全丧失，但目前的修复技术不足以解决无法治疗的视力障碍-AMD的主要原因。视网膜下光伏阵列可以提供足够的视力，用于恢复AMD致盲患者的中心视力。
Objective. Retinal prostheses aim to restore sight by electrically stimulating the surviving retinal neurons. In clinical trials of the current retinal implants, prosthetic visual acuity does not exceed 20/550. However, to provide meaningful restoration of central vision in patients blinded by age-related macular degeneration (AMD), prosthetic acuity should be at least 20/200, necessitating a pixel pitch of about 50 mu m or lower. With such small pixels, stimulation thresholds are high due to limited penetration of electric field into tissue. Here, we address this challenge with our latest photovoltaic arrays and evaluate their performance in vivo. Approach. We fabricated photovoltaic arrays with 55 and 40 mu m pixels (a) in flat geometry, and (b) with active electrodes on 10 mu m tall pillars. The arrays were implanted subretinally into rats with degenerate retina. Stimulation thresholds and grating acuity were evaluated using measurements of the visually evoked potentials (VEP). Main results. With 55 mu m pixels, we measured grating acuity of 48 +/- 11 mu m, which matches the linear pixel pitch of the hexagonal array. This geometrically corresponds to a visual acuity of 20/192 in a human eye, matching the threshold of legal blindness in the US (20/200). With pillar electrodes, the irradiance threshold was nearly halved, and duration threshold reduced by more than three-fold, compared to flat pixels. With 40 mu m pixels, VEP was too low for reliable measurements of the grating acuity, even with pillar electrodes. Significance. While being helpful for treating a complete loss of sight, current prosthetic technologies are insufficient for addressing the leading cause of untreatable visual impairment-AMD. Subretinal photovoltaic arrays may provide sufficient visual acuity for restoration of central vision in patients blinded by AMD.