ELECTRICAL ALTERNATIVE LASERS INTRAOCULAR MICROSURGERY

我们建议开发和评估一种基于脉冲等离子体介导的液体介质中软组织剥离的高精度、低成本的眼科手术电切割器。该设备的首批应用之一将是玻璃体视网膜手术，即无牵引力地去除玻璃体视网膜膜。治疗玻璃体视网膜膜的常用技术是机械分割、剥离或分层，其中 很大程度的牵引力通常作用于视网膜下的组织，这会导致内层受损、医源性撕裂和出血。人们曾多次尝试开发基于激光的玻璃体视网膜手术器械，但到目前为止，由于广泛的附带组织损伤或这些系统的高成本和低效率，所有这些系统都未能获得广泛接受。液体介质中激光-组织相互作用最强大的机制之一是基于介质击穿的等离子体产生。这种方法基于紧密聚焦短脉冲激光的应用，由于在实际操作条件下难以将激光束紧密聚焦在视网膜附近，因此在玻璃体视网膜手术中尚未被临床接受。我们建议使用类似的相互作用机制，但不使用激光。通过眼内微电极施加的亚微秒高压放电将在液体介质中产生等离子体，并允许对软组织进行精确切割。能量沉积被限制在由电极大小决定的区域内--大约几微米--从而允许非常低的阈值能量和非常精细的穿透深度控制。该系统结合了高精度、可靠性、通用性和低成本，将在操作实践中得到广泛接受。这种方法在玻璃体视网膜手术和其他眼内手术，如囊膜切开术和白内障手术中的适用性将在体外和动物模型上进行测试，包括组织学分析、扫描电子显微镜和生理测试。

We propose to develop and evaluate a precise yet low cost electric operative cutting instrument for ophthalmic surgery based on pulsed plasma-mediated dissection of soft tissue in liquid medium. One of the first applications of this device will be in vitreoretinal surgery, namely, for tractionless removal of vitreoretinal membranes. The common techniques for treatment of vitreoretinal membranes are mechanical segmentation, peeling or delamination where a significant degree of traction is often applied to the underlying retinal tissue, and this can induce damage to the internal layers, iatrogenic tears and bleeding. Several attempts to develop laser- based instrumentation for vitreoretinal surgery have been undertaken, but all these systems have failed so far to achieve widespread acceptance due to either extensive collateral tissue damage, or high cost and low efficiency of these systems. One of the most powerful mechanisms of laser-tissue interaction in liquid medium is dielectric breakdown-based plasma generation. This approach, based on application of tightly focused short pulse lasers, has not been accepted clinically in vitreoretinal surgery due to difficulties with tight focusing of the laser beam near the retina in real operational conditions. We propose to use a similar interaction mechanism but without lasers. A sub-microsecond high voltage discharge applied via an intraocular microelectrode will generate plasma in liquid medium and can allow for precise cutting of soft tissue. The energy deposition is confined to the area determined by the size of the electrode - on the order of a few micrometers - thus allowing for very low threshold energy and very fine control of the penetration depth. This system combining high precision, reliability and versatility with low cost will allow for widespread acceptance in operating practice. Applicability of this approach to vitreoretinal surgery and other intraocular procedures, such as capsulotomy and cataract surgery will be tested in-vitro and on animal models including histological analysis, scanning electron microscopy and physiological tests.