脉络膜上腔视觉假体刺激参数的选择  

Choices of stimulus parameters by suprachoroidal-transretinal visual prosthesis

作　　者：梁婷[1] 范明[2] 马兰茗[1] 隋晓红[3] 

机构地区：[1]哈尔滨医科大学附属第四医院眼科,黑龙江省哈尔滨市150001 [2]哈尔滨医科大学附属第二医院心外科,黑龙江省哈尔滨市150086 [3]上海交通大学激光与光子医学生物研究所,上海市200240

出　　处：《眼科新进展》2014年第2期127-130,共4页Recent Advances in Ophthalmology

基　　金：黑龙江省卫生厅科研课题(编号:2011-164)~~

摘　　要：目的探讨脉络膜上腔电刺激参数优化的组合方式,指导实际应用中脉络膜上腔视觉假体刺激方案的选择。方法将带有不同尺寸刺激点(50μm、150μm、350μm、500μm)的薄膜电极植入白兔脉络膜上腔,进行跨视网膜电刺激,于动物的视觉皮层硬脑膜外记录电诱发电位(electrical evoked potential,EEP)。实验中采用的刺激脉冲波形为先负后正或先正后负的双相脉冲,脉冲宽度分别为0.25 ms、0.50 ms、0.75 ms和1.00 ms,刺激频率为1 Hz、2 Hz和4 Hz。结果实验中无论采用哪种尺寸的电极进行刺激,整体上诱发EEP所需的阈电流均随着脉冲宽度的增加而减小,随着刺激频率的增加而增加。当刺激频率从1 Hz增加到4 Hz时,阈电流增加的幅度在短脉冲宽度(0.25 ms)刺激时为77%(500μm电极)和170%(150μm电极);在长脉冲宽度(1.0 ms)刺激时,增加的幅度较低,约为38%(500μm电极)和131%(150μm电极)。与此同时先负后正的刺激脉冲所需的阈电流总是低于先正后负的刺激脉冲所需的阈电流。结论由于采用大尺寸的电极伴以长脉冲宽度刺激时,诱发EEP所需的阈电流强度随刺激频率增加的幅度较小,此外先负后正的刺激脉冲所需的阈电流也相对较低,因此这些都将成为脉络膜上腔视觉假体未来应用中优先选择的刺激方案。Objective To fred the optimized combination mode of various stimu- lus parameters by suprachoroidal-transretinal stimulation （ STS）, and provide the impor- tant reference to choose stimulus parameters during the usage of the STS visual prosthe- sis. Methods A electrode array with four size electrode contacts （50 μm, 150 μm,350 μm and 500 μm in diameter） was implanted into the suprachoroidal space of the rabbit eyes. The electrical evoked potential （EEP）was recorded extradurally on the visual cor- tex, and the stimulus current was a biphasic current pulse with anodic- or cathodic-first stimulation at the pulse durations （0.25 ms, 0.50 ms, 0.75 ms and 1.00 ms）. Stimulus frequency was applied at 1 Hz ,2 Hz and 4 Hz. Results With any one of these different sized electrodes, the threshold currents required to elicit EEP decreased as the stimulus pulse duration increased. And the threshold currents increased with the stimulus fre- quency increasing. We calculated the increased ratio of threshold currents between 4 Hz and 1 Hz. With 0.25 ms current pulses, the increased ratio was 77% with the 500 μm e- lectrode and 170% with the 150 μm electrode. At the longest tested stimulus pulse （ 1.0 ms） ,the increased ratios were 38% with the 500 μm electrode and 131% with the 150 μm electrode. The threshold current for the cathodic-first stimulation was always lower than that of the anodic-first stimulation. Conclusion The increased ratio of the threshold currents with the simulus frequency increasing is shown to be the lowest in the presence of the large surface electrode with long-duration. And the threshold current is low with the cathodic-first stimulation. Herein, these stimulus manners are suggested to be preferable for the STS visual prosthesis.

关 键 词：电刺激 电极 脉络膜上腔 阈电流 视觉假体 

分 类 号：R779.606[医药卫生—眼科]