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Yan Y.,Shanghai JiaoTong University | Sui X.,Shanghai JiaoTong University | Liu W.,Shanghai JiaoTong University | Liu W.,Shanghai Eye Research Institute | And 6 more authors.
Graefe's Archive for Clinical and Experimental Ophthalmology | Year: 2015

Background: Suprachoroidal-transretinal stimulation (STS) can potentially restore vision. This study investigated the spatial characteristics of cortical electrical evoked potentials (EEPs) elicited by STS. Methods: A 4 × 4 thin-film platinum microelectrode stimulating array (200 μm electrode diameter and 400 μm center-to-center distance) was fabricated by a micro-electro-mechanical systems (MEMS) techniques and implanted into the suprachoroidal space of albino rabbits. Results: The current threshold to elicit reliable EEPs by a single electrode was 41.6 ± 12.6 μA, corresponding to a 66.2 ± 20.1 μC · cm−2 charge density per phase, which was lower than the reported safety limits. Spatially differentiated cortical responses could be evoked by STS through different rows or columns of electrical stimulation; furthermore, shifts in the location of the maximum cortical activities were consistent with cortical visuotopic maps; increasing the number of simultaneously stimulating electrodes increased the response amplitudes of EEPs and expanded the spatial spread as well. In addition, long-term implantation and electrical stimulation of the MEMS electrode array in suprachoroidal space are necessary to evaluate systematically the safety and biocompatibility of this approach. Conclusions: This study indicates that the STS approach by a MEMS-based platinum electrode array is a feasible alternative for visual restoration, and relatively high spatial discrimination may be achieved. © 2015, Springer-Verlag Berlin Heidelberg. Source


Cao P.,Shanghai JiaoTong University | Sun J.,Shanghai JiaoTong University | Yan Y.,Shanghai JiaoTong University | Chen Y.,Shanghai JiaoTong University | And 5 more authors.
Graefe's Archive for Clinical and Experimental Ophthalmology | Year: 2015

Purpose: To investigate the effect of different stimulation modes on cortical electrically evoked potentials (EEPs) by intraorbital optic nerve (ON) stimulation with penetrating electrodes. Methods: A stimulating electrode array with three electrodes arranged linearly was inserted into the ON along its axis. EEPs were recorded using a 4 × 4 silver-ball electrode array in response to monopolar and bipolar stimulation mode, respectively. Results: The simultaneous monopolar stimulation mode had a lower threshold than the individual monopolar stimulation mode, but elicited smaller cortical response when a fixed charge was injected. The threshold of the bipolar stimulation mode was comparable to that of individual monopolar stimulation mode. The response to the smaller spacing (150 μm) bipolar stimulation mode was similar in amplitude to that of the individual monopolar stimulation mode, but spread wider. The larger spacing (500 μm) bipolar stimulation mode elicited stronger and wider response than the individual monopolar stimulation mode. For the individual monopolar stimulation mode, stimulation with different electrodes can be differentiated even when the spacing of the two electrodes was 150 μm. Conclusions: For ON stimulation with penetrating electrodes, the monopolar stimulation mode could induce more localized cortical responses than the bipolar stimulation mode with comparable threshold and had a high stimulation selectivity. These findings may provide valuable information for the design of stimulation strategy of the penetrative ON visual prosthesis. © 2015, Springer-Verlag Berlin Heidelberg. Source


Liu W.,Shanghai JiaoTong University | Liu W.,Shanghai Eye Research Institute | Song Z.,Shanghai JiaoTong University | Song Z.,Shanghai Eye Research Institute | And 21 more authors.
Current Eye Research | Year: 2012

Purpose: The photosensitive polyimide film, Durimide, is a common component of retinal prostheses; however, retinal cell response to Durimide has not been effectively studied This work assessed the in vitro biocompatibility of a retinal prosthesis containing platinum-electrode embedded Durimide film. Materials and methods: Biocompatibility evaluation assessed cytotoxicity, attachment, and proliferation of two cell lines: a human retinal pigmented epithelium cell line (CRL) and a rhesus monkey choroid-retinal endothelial cell line (RF/6A). Cells were cultured with the platinum-electrode embedded Durimide film, with tissue-culture treated polystyrene plates (TCPS) used as a control substrate for cell growth. The effect of a Durimide-exposed medium on cell apoptosis and life cycle was assessed using flow cytometry (FCM). Results: The indirect cytotoxicity evaluation revealed no toxic effect of the prosthesis on cells. The attachment and proliferation of CRL and RF/6A cells cultured with the Durimide prostheses showed no significant differences to the control. The FCM experiments demonstrated a liquid medium exposed to the prosthesis had no effects on apoptosis or cell life cycle in comparison with the control (p > 0.05). Conclusions: The results demonstrate that Durimide has good biocompatibility with retinal cell lines CRL and RF/6A. In conclusion, while further in vitro and in vivo studies are required to clarify long-term effects, Durimide is indicated as a promising material with suitable biocompatibility for retinal implants. © 2012 Informa Healthcare USA, Inc. Source


Liu Y.,Shanghai JiaoTong University | Zhang-Nunes S.,University of California at Los Angeles | Zhu X.,Shanghai JiaoTong University | Xu X.,Shanghai Eye Research Institute | And 2 more authors.
Journal of Clinical Neuroscience | Year: 2013

A 70-year-old man presented with left-sided eye pain, impaired vision and restricted left ocular motility, later developing progressive visual decline with development of ataxia and incontinence. Fundoscopic examination revealed significant optic nerve head edema and hemorrhage on the left eye. Neuroimaging revealed an optic pathway mass, extending from the right optic nerve to the chiasm, which enlarged on serial imaging. After surgical excision of the mass, pathology showed a grade III astrocytoma. The patient died 16 months after presentation, which is longer than previously reported for late adult onset optic pathway astrocytoma. We believe that neuroimaging and pathological studies should be performed early in such patients to allow early diagnosis and intervention. © 2013 Elsevier Ltd. All rights reserved. Source


Zhang L.,Shanghai JiaoTong University | Wang F.,Shanghai Eye Research Institute | Jiang Y.,Shanghai JiaoTong University | Jiang Y.,Shanghai Eye Research Institute | And 8 more authors.
Frontiers in Bioscience - Scholar | Year: 2013

Abnormal migration of retinal pigment epithelium (RPE) contributes to a variety of disorders such as proliferative vitreoretinopathy. Here, the effect of epidermal growth factor (EGF), and signaling by its receptor (ERGR)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) on RPE cell migration was studied. The in vitro wound healing and migration of the human RPE cell line, ARPE19 cell was accelerated, in a dose dependent manner, in response to EGF stimulation, while pretreatment with EGFR, PI3K or AKT inhibitor, inhibited both events. Exposure of cells to EGF activated the AKT phosphorylation, whereas EGFR and PI3K inhibitors blocked EGFinduced AKT phosphorylation in a dose-dependent manner. These data suggest that EGF mediate ARPE-19 cell migration through EGFR/PI3K/AKT signaling pathway. Source

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