Electrophysiological and histological studies of chronically implanted intrapapillary microelectrodes in rabbit eyes
Electrophysiological and histological studies of chronically implanted intrapapillary microelectrodes in rabbit eyes
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DOI：
10.1007/s00417-005-0073-9
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发表时间：
2006-03
期刊：
影响因子：
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通讯作者：
X. Fang;H. Sakaguchi;T. Fujikado;M. Osanai;Y. Ikuno;M. Kamei;M. Ohji;T. Yagi;Y. Tano
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文献类型：
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作者：
X. Fang;H. Sakaguchi;T. Fujikado;M. Osanai;Y. Ikuno;M. Kamei;M. Ohji;T. Yagi;Y. Tano
目的探讨经巩膜植入兔眼视神经头的安全性和有效性。方法将4个铂丝微电极经巩膜植入5只兔眼的视神经头内，植入4~6个月。用彩色眼底照相、荧光素血管造影、视网膜电信号(ERG)和视觉诱发电位(VEP)监测视网膜。电诱发电位(EEPS)在植入后即刻和之后每隔1个月用四个电极的不同组合对视神经轴突进行双极电刺激诱发。分别于植入后4个月和6个月通过组织学和免疫组织化学方法观察植入电极对视神经形态的影响。结果除1个电极在植入后1个月脱离视神经头外，其余电极在植入后的整个时间内均保持稳定。无眼内感染、炎症或玻璃体视网膜增生。在所有测试时间内，每对电极均可激发出EEP。诱发EEPS的平均阈值电流(电荷密度)从植入当天的19.3±9.2μA(6.0±2.9μC/cm~2)增加到植入后1个月的78.8±31.9μA(24.6±10.0μC/cm~2)，但此后无明显变化。ERG的a波、b波和VEP的P_1波的潜伏期和波幅在植入后整个过程中均无明显变化。视神经头的组织学检查显示电极周围有轻微的组织包裹，视神经表面附近胶质纤维酸性蛋白的表达增加。结论经巩膜内乳头内微电极植入是安全有效的。这些发现表明，视神经基假体应考虑在视神经头内植入微电极。
PurposeTo determine the safety and efficacy of transsclerally placed intrapapillary wire microelectrodes implanted chronically into the optic nerve head of rabbit eyes.MethodsFour platinum wire microelectrodes were passed through the sclera and implanted into the optic nerve head of five rabbit eyes for 4–6 months. Color fundus photography, fluorescein angiography, electroretinograms (ERGs), and visually evoked potentials (VEPs) were used to monitor the retina. Electrically evoked potentials (EEPs) were elicited by bipolar electrical stimulation of the optic nerve axons by different combinations of the four electrodes immediately after the implantation and at 1-month intervals thereafter. The effects of the chronic implantation of the electrodes on the morphology of the optic nerve were evaluated by histological and immunohistochemical examinations at 4 and 6 months after the implantation.ResultsAll of the electrodes remained stable in the implanted sites throughout the post-implantation period, except for one electrode that had pulled out of the optic nerve head at 1 month after implantation. No intraocular infection, inflammation, or vitreoretinal proliferation was observed in any eye. EEPs could be elicited from each pair of electrodes at all testing times. The mean threshold currents (charge densities) to evoke EEPs increased from 19.3±9.2 μA (6.0±2.9 μC/cm2) on the implantation day to 78.8±31.9 μA (24.6±10.0 μC/cm2) at 1 month after implantation, but did not change significantly thereafter. The implicit time and amplitude of the a- and b-waves of the ERGs and of P1 of the VEPs did not change significantly throughout the post-implantation period. Histological evaluation of the optic nerve head revealed slight tissue encapsulations surrounding the electrode and increased expression of glial fibrillary acidic protein near the surface of the optic nerve.ConclusionsImplantation of transscleral intrapapillary microelectrodes appears to be safe and effective. These findings indicate that the implantation of microelectrodes in the optic nerve head should be considered for an optic nerve-based prosthesis.