Improving the spatial resolution of epiretinal implants by increasing stimulus pulse duration.
Improving the spatial resolution of epiretinal implants by increasing stimulus pulse duration.
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DOI：
10.1126/scitranslmed.aac4877
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发表时间：
2015-12-16
影响因子：
17.1
通讯作者：
Weiland JD
中科院分区：
文献类型：
--
作者：
Weitz AC;Nanduri D;Behrend MR;Gonzalez-Calle A;Greenberg RJ;Humayun MS;Chow RH;Weiland JD
视网膜假体植入是治疗视网膜色素变性的唯一被批准的治疗方法，视网膜色素变性是一种通过光感受器逐渐退化而导致失明的眼部疾病。由摄像头的输入触发的微电极阵列刺激存活的视网膜神经元，每个电极充当一个像素。意外刺激视网膜神经节细胞轴突会导致患者看到大而长圆形的光，而不是焦点，使他们难以感知形状。为了解决这个问题，我们在分离的视网膜上进行了钙成像，并绘制了不同电刺激方案激活的细胞模式。我们发现，脉冲持续时间比现有植入物中通常使用的脉冲持续时间长两个数量级，刺激视网膜内部神经元，同时避免神经节细胞轴突激活，从而将视网膜反应限制在电极位置。我们表明，用25ms脉冲的多电极刺激可以在视网膜上形成对应于Snellen敏感度为20/312的字母。我们在一位植入了视网膜前假体的患者身上验证了我们的发现，证明了25毫秒的脉冲可以唤起焦点光。
Retinal prosthetic implants are the only approved treatment for retinitis pigmentosa, a disease of the eye that causes blindness through gradual degeneration of photoreceptors. An array of microelectrodes triggered by input from a camera stimulates surviving retinal neurons, each electrode acting as a pixel. Unintended stimulation of retinal ganglion cell axons causes patients to see large, oblong shapes of light, rather than focal spots, making it difficult for them to perceive forms. To address this problem, we performed calcium imaging in isolated retinas and mapped the patterns of cells activated by different electrical stimulation protocols. We found that pulse durations two orders of magnitude longer than those typically used in existing implants stimulate inner retinal neurons while avoiding activation of ganglion cell axons, thus confining retinal responses to the site of the electrode. We show that multielectrode stimulation with 25-ms pulses can pattern letters on the retina corresponding to a Snellen acuity of 20/312. We validated our findings in a patient with an implanted epiretinal prosthesis by demonstrating that 25-ms pulses evoke focal spots of light.