【作者】 刘广峰；

【导师】 董方田； 钟勇； 陈有信；

【作者基本信息】 中国协和医科大学 ， 眼科学， 2010， 博士

【摘要】 目的：研究新型的以二氯代环二聚体(parylene C)为基底的平面铂微电极阵列芯片(microelectrode array, MEA)和以parylene C为基底的三维铂MEA芯片在兔脉络膜上腔的组织相容性；这两种微电极芯片兔眼脉络膜上腔植入术的手术情况；及这两种芯片于脉络膜上腔跨视网膜电刺激(suprachoroidal transretinal stimulation, STS)诱发电诱发电位(electrical evoked potential, EEP)的阂值。方法：第一部分：研制了以parylene C为基底的平面铂MEA芯片和以parylene C为基底的三维铂MEA芯片。12只健康成年青紫兰兔,随机分成A组、B两组,A组植入以parylene C为基底的平面铂MEA芯片；B组植入以paryleneC为基底的三维铂MEA芯片。所有青紫兰兔均以左眼为手术眼,于鼻下方角膜缘后6mm处切开巩膜暴露脉络膜,将微电极阵列放置于兔眼后极部脉络膜上腔,术后3 d、14 d、1个月、3个月观察芯片位置,OCT扫描研究植入术后微电极阵列芯片与视网膜、脉络膜的关系,并分析手术并发症情况,3个月进行组织学检测。第二部分：18只健康成年青紫兰兔,随机分成A、B两组,A组植入以parylene C为基底的平面铂MEA芯片；B组植入以parylene C为基底的三维铂MEA芯片。将多通道刺激电极芯片放置于兔眼后极部的脉络膜上腔,将铂丝制成的参比电极放置于玻璃体腔,视皮质区硬膜外放置记录电极。先记录视觉诱发电位,之后刺激电极采用双向刺激的方式发出电刺激,在中枢记录电诱发电位。测量产生电诱发法电位的阈值,连续记录30次取其平均值。实验结束后处死动物取出眼球行组织学检查。结果：第一部分：12只眼都成功的植入MEA芯片。A组术中1只眼(8.3%)切开巩膜时损伤脉络膜,视网膜也随之破裂,少量玻璃体流出,缝合巩膜切口,在其切口鼻侧重新植入芯片。A组5只眼(41.6%)、B组3只眼(25.0%)在术中切开巩膜时损伤脉络膜血管,发生少量脉络膜出血,待出血停止后再清除凝血继续手术,两组均有2只眼(16.7%)在芯片植入后手术显微镜下用角膜接触镜观察时发现芯片前端折叠,取出芯片展平后重新植入,可见芯片位于脉络膜大血管下,芯片平整。植入后眼底、OCT检查见芯片平整位于脉络膜上腔；组织学检查未见明显的组织病理改变。第二部分：头部电极植入及脉络膜上腔MEA芯片植入术后,光刺激可以记录到光诱发电位(visual evoked potential, VEP);当脉络膜上腔刺激电极发出电刺激后,可以在硬脑膜外的记录电极处记录到电诱发电位(electrical evoked potential, EEP),A组兔的VEP振幅为169±58μV,潜伏期为22.3±1.4 ms(图2A)；B组兔的VEP振幅为176±53μV,潜伏期为24.5±1.9 ms,二者振幅和潜伏期无统计学差异(P>0.05)。在双向刺激电流的作用下,两组MEA电刺激都可以产生EEP,典型的图像早期为连续的负波,之后是正向波。经测量A组产生EEP的电量阈值平均值为143.3±27.84 nC,最大值200nC,最小值120nC；电荷密度阈值的平均值为91.29±17.73μC cm-2,最大值为127.39μC cm-2,最小值为76.43μC cm-2。B组的电量阈值为86.67±18.03 nC,最大值120nC,最小值70nC；电荷密度阈值的平均值为55.20±11.48μC cm-2,最大值为76.43μC cm-2,最小值为44.59μC cm-2。A组与B组的电荷密度阈值具有统计学差异(t=5.12,P<0.05)。结论：兔眼脉络膜上腔微电极阵列芯片植入术是一种安全有效的植入方式,脉络膜上腔是理想视网膜刺激电极位置。以parylene C为基底的铂MEA芯片组织相容性良好,是理想的人工视网膜假体。以parylene C为基底的铂MEA芯片于脉络膜上腔可以有效地行跨视网膜电刺激,并且可以在兔视皮质区检测到电诱发电位；三维电极相对于平面电极行电刺激的阈值更小。更多还原

【Abstract】 Object:To investigated the surgical procedure, complications, OCT appearance histological changes and the biocompatibllity of the planar and 3D Parylene-based multichannel electrode array in the suprachoroidal of rabbit eyes; investigated the threshold electrical charge density of the retina in rabbits for the generation of electrical evoked potentials (EEP) by delivering electrical stimulation with the planar and 3D Parylene-based multichannel electrode array implanted into the suprachoroidal space.Methods:Part one:1 flat electrode array (parylene plate, platinum electrode) and 1 3D electrode array were developed and used for this study. After performing a scleral incision at 6mm from the limbus and placing an anchoring suture, the array was inserted into the suprachoroidal space in the posterior portion of the eye by direct observation under a microscope,12 adult healthy chinchilla rabbits which were divided in to A group (planar MEA) and B group (3D MEA). The clinical examination including direct ophthalmoscope, and optical coherence tomography were performed in 3day,14 day,1 month and 3 month. The histological examinations were performed at 3month under light microscope.Part two:18 adult healthy chinchilla rabbit were divided in to A group (planar MEA) and B group (3D MEA), the array was inserted into the suprachoroidal space in the posterior portion of the eye. A platinum wire was implanted into the vitreous space as a reference electrode. For electrical stimulation, a biphasic pulse was used. When the electrodes were stimulated, the EEP was recorded. The retinal threshold for generation of an EEP was determined for each MEA placement by consisting of 30 computer-averaged recordings. Animals were sacrificed at the conclusion of the experiment and the eyes were enucleated for histological examination.Results:Part one:All the electrode arrays were successfully inserted into the suprachoroidal space of rabbits. In A group,1 eye the choroid and retina were injured during the surgery.5 eyes in group A and 3eyes in group Bthe choroid were damaged with mild hemorrhage during the surgery. Optical coherence tomography demonstrated good position of the arrays, and no significant retinal edema and retinal detachment were observed. Histological examination showed no significant inflammatory changes in both group. Part two:When the electrical stimulation from the suprachoroidal space was applied, the EEP could be recorded with an epidural electrode, and the average charge threshold of group A was 143.3±27.84 nC, chang density 91.29±17.73 cm-2, maximum charge threshold was 200nC change density 127.39μC cm-2, minimum charge threshold was 120nC, change density 76.43μC cm-2; the average charge threshold of group B was 86.67±18.03 nC, charge density was 55.20±11.48μC cm-2, maximum charge threshold was 120nC, charge density was 76.43μC cm-2, minimum charge threshold was 70μC cm-2,charge density was 44.59 u C cm-2. Histological examination indicated the absence of major damage to the retina and choroid from the insertion place of the array and the electrical stimulation.Conclusion:Suprachoroidal multichannel electrode array insertion is a safe surgery, with little damage to the retina and choroid and no significant inflammatory change after surgery. Transretinal electrical stimulation from the suprachoroidal space could elicit EEP, suggesting that this approach may be useful for a retinal prosthesis system.3D MEA had a lower threshold than planar MEA.更多还原