Factors affecting perceptual thresholds in epiretinal prostheses
Factors affecting perceptual thresholds in epiretinal prostheses
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DOI：
10.1167/iovs.07-0696
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发表时间：
2008-06-01
影响因子：
4.4
通讯作者：
Fine, Ione
中科院分区：
文献类型：
--
作者：
de Balthasar, Chloe;Patel, Sweta;Fine, Ione
目的.目的是评估感知阈值与电极阻抗、电极尺寸、电极距视网膜表面的距离以及视网膜厚度之间的关系。S.美国食品药品监督管理局（FDA）批准的临床试验。植入物由眼外单元和眼内单元组成，眼外单元包含用于无线数据、功率恢复和刺激电流生成的电子器件，眼内单元包含以4 × 4模式排列的16个铂刺激电极（直径260或520 μ m）。电极阵列通过小大头钉固定在视网膜上。刺激由基于计算机的外部系统控制，该系统允许对每个电极进行独立控制。每两周测量一次每个电极的感知阈值（在79%的试验中，观察患者所需的电流）和阻抗。电极与视网膜表面的距离和视网膜厚度通过光学相干断层扫描仪在不太定期的基础上测量。结果检测光幻视的刺激阈值与电极距视网膜表面的距离相关，但与电极大小、电极阻抗或视网膜厚度无关。保持电极阵列和视网膜表面之间的紧密接近对于开发成功的视网膜植入物至关重要。随着在视网膜表面上稳定且齐平的慢性电极阵列的发展，其他因素（例如电极尺寸、视网膜变性和受试者年龄）的影响可能会变得更加明显。（ClinicalTrials.gov编号，NCT 00279500。）
PURPOSE. The goal was to evaluate how perceptual thresholds are related to electrode impedance, electrode size, the distance of electrodes from the retinal surface, and retinal thickness in six subjects blind as a result of retinitis pigmentosa, who received epiretinal prostheses implanted monocularly as part of a U. S. Food and Drug Administration (FDA)-approved clinical trial.METHODS. The implant consisted of an extraocular unit containing electronics for wireless data, power recovery, and generation of stimulus current, and an intraocular unit containing 16 platinum stimulating electrodes (260- or 520-mu m diameter) arranged in a 4 x 4 pattern. The electrode array was held onto the retina by a small tack. Stimulation was controlled by a computer-based external system that allowed independent control over each electrode. Perceptual thresholds (the current necessary to see a percept on 79% of trials) and impedance were measured for each electrode on a biweekly basis. The distance of electrodes from the retinal surface and retinal thickness were measured by optical coherence tomography on a less regular basis. RESULTS. Stimulation thresholds for detecting phosphenes correlated with the distance of the electrodes from the retinal surface, but not with electrode size, electrode impedance, or retinal thickness.CONCLUSIONS. Maintaining close proximity between the electrode array and the retinal surface is critical in developing a successful retinal implant. With the development of chronic electrode arrays that are stable and flush on the retinal surface, it is likely that the influence of other factors such as electrode size, retinal degeneration, and subject age will become more apparent. (ClinicalTrials.gov number, NCT00279500.).