Wang Kai, Li Xiao-Qian, Li Xiao-Xin, Pei Wei-Hua, Chen Hong-Da, Dong Jian-Qiang
Ophthalmology Department, Peking University People's Hospital, 11 Xi Zhi Men Nan Street, Xi Cheng District, Beijing 100044, China.
Vision Res. 2011 Sep 1;51(17):1897-906. doi: 10.1016/j.visres.2011.06.019. Epub 2011 Jul 7.
In addition to epiretinal and subretinal areas, the optic nerve (ON) is also a candidate location for implanting visual prosthesis to restore vision of patients with retinitis pigmentosa (RP). Since the ON receives all the signals from the retina, stimulating the ON may potentially evoke phosphenes over a wider range of visual field. In this study, we designed a 9-channel microelectrode array and implanted it between the dura mater and pia mater of rabbit ONs by lateral orbitotomy. We recorded the current thresholds and evaluated the efficacy of the array using electrically evoked potentials (EEPs). Spatial discrimination of approximately 20° was verified by EEP maps over visual cortex. A large area of the visual field (over 130° along horizontal meridian) could be activated by this microelectrode array. Visual evoked potentials (VEPs) and different pathological examinations were used to examine potential damage of ONs. One year post implantation, we did not notice significant damages to either the ONs or the microelectrode arrays. EEPs were successfully recorded up to 6months post implantations. However, further studies are still needed to reduce fibrous encapsulation of the microelectrode array, which resulted in a gradual elevation of current thresholds to elicit EEPs.
除了视网膜前和视网膜下区域外，视神经（ON）也是植入视觉假体以恢复视网膜色素变性（RP）患者视力的候选位置。由于视神经接收来自视网膜的所有信号，刺激视神经可能会在更广泛的视野范围内诱发光幻视。在本研究中，我们设计了一种9通道微电极阵列，并通过外侧眶切开术将其植入兔视神经的硬脑膜和软脑膜之间。我们记录了电流阈值，并用电诱发电位（EEPs）评估了该阵列的功效。通过视觉皮层上的EPP图验证了约20°的空间辨别力。该微电极阵列可激活大面积的视野（沿水平子午线超过130°）。使用视觉诱发电位（VEPs）和不同的病理检查来检查视神经的潜在损伤。植入后一年，我们未发现视神经或微电极阵列有明显损伤。植入后长达6个月成功记录到了EPPs。然而，仍需要进一步研究以减少微电极阵列的纤维包裹，这导致引发EPPs的电流阈值逐渐升高。
