眼外电刺激已知为视网膜和视神经疾病中的视网膜细胞提供神经保护。目前,由于缺乏可植入的刺激装置,治疗方法要求患者设置眼外电极并可能每周进行一次刺激.因此,开发了一种微创植入物来为视网膜提供慢性电刺激,有可能改善患者长期使用的依从性。本研究的目的是确定这种用于神经保护性刺激的新型设备的手术和刺激安全性。
■将8名正常视力的成年猫科动物单眼植入周边视网膜的脉络膜上腔9-39周。电荷平衡,双相,电流脉冲(100μA,500µs脉冲宽度和50脉冲/s)连续输送到铂电极3-34周。每小时测量电极阻抗。视网膜结构和功能在1-,2-,4-,6个月和8个月使用视网膜电图,光学相干层析成像和眼底摄影。从组织学切片测量视网膜和纤维化厚度。随机化,对刺激和非刺激视网膜进行盲化组织病理学评估.
■所有受试者均耐受手术和刺激程序,没有不适或意外不良结果的证据。在手术后的沉降期后,装置位置是稳定的。随着时间的推移,中值电极阻抗保持在一致的范围(5-10kΩ)内。视网膜厚度或功能相对于基线和其他眼没有变化。纤维囊厚度在刺激和非刺激组织之间是相等的,并且有助于将装置保持在适当位置。没有疤痕,插入创伤,坏死,来自植入眼睛的任何视网膜样本中的视网膜损伤或成纤维细胞反应,而19%的人有最小的组织细胞反应,19%有轻微至轻度急性炎症,28%有轻微至轻度慢性炎症。
■使用微创设备对视网膜进行慢性超阈值电刺激可引起轻微的组织反应,并且没有不良的临床发现。使用植入设备的周围脉络膜上电刺激可能是用于递送神经保护性刺激的经角膜电刺激的替代方法。
UNASSIGNED: Extraocular electrical stimulation is known to provide neuroprotection for retinal cells in retinal and optic nerve diseases. Currently, the treatment approach requires patients to set up extraocular electrodes and stimulate potentially weekly due to the lack of an implantable stimulation device. Hence, a minimally-invasive implant was developed to provide chronic electrical stimulation to the retina, potentially improving patient compliance for long-term use. The aim of the present
study was to determine the surgical and stimulation safety of this novel device designed for neuroprotective stimulation.
UNASSIGNED: Eight normally sighted adult feline subjects were monocularly implanted in the suprachoroidal space in the peripheral retina for 9-39 weeks. Charge balanced, biphasic, current pulses (100 μA, 500 µs pulse width and 50 pulses/s) were delivered continuously to platinum electrodes for 3-34 weeks. Electrode impedances were measured hourly. Retinal structure and function were assessed at 1-, 2-, 4-, 6- and 8-month using electroretinography, optical coherence tomography and fundus photography. Retina and fibrotic thickness were measured from histological sections. Randomized, blinded histopathological assessments of stimulated and non-stimulated retina were performed.
UNASSIGNED: All subjects tolerated the surgical and stimulation procedure with no evidence of discomfort or unexpected adverse outcomes. The device position was stable after a post-surgery settling period. Median electrode impedance remained within a consistent range (5-10 kΩ) over time. There was no change in retinal thickness or function relative to baseline and fellow eyes. Fibrotic capsule thickness was equivalent between stimulated and non-stimulated tissue and helps to hold the device in place. There was no scarring, insertion trauma, necrosis, retinal damage or fibroblastic response in any retinal samples from implanted eyes, whilst 19% had a minimal histiocytic response, 19% had minimal to mild acute inflammation and 28% had minimal to mild chronic inflammation.
UNASSIGNED: Chronic suprathreshold electrical stimulation of the retina using a minimally invasive device evoked a mild tissue response and no adverse clinical findings. Peripheral suprachoroidal electrical stimulation with an implanted device could potentially be an alternative approach to transcorneal electrical stimulation for delivering neuroprotective stimulation.