ELECTRICAL ALTERNATIVE LASERS INTRAOCULAR MICROSURGERY

我们建议开发和评估一种精确而低成本的电动手术切割仪器，用于眼科手术的基础上脉冲等离子体介导的液体介质中的软组织解剖。该装置的最初应用之一将是在玻璃体视网膜手术中，即用于无牵引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， 显著程度的牵引经常被施加到下面的视网膜组织，并且这可能引起对内层的损伤、医源性撕裂和出血。已经进行了几次开发用于玻璃体视网膜手术的基于激光的仪器的尝试，但是由于广泛的附带组织损伤或者这些系统的高成本和低效率，所有这些系统迄今为止都未能获得广泛的接受。 液体介质中激光与生物组织相互作用的最强机制之一是基于介质击穿的等离子体产生。这种基于紧密聚焦的短脉冲激光器的应用的方法在玻璃体视网膜手术中尚未被临床接受，这是由于在真实的手术条件下激光束在视网膜附近紧密聚焦的困难。我们建议使用类似的相互作用机制，但没有激光。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，并且可以允许精确切割软组织。能量沉积被限制在由电极的尺寸确定的区域（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。该系统具有高精度、高可靠性和低成本的多功能性，将在操作实践中被广泛接受。将在体外和动物模型上测试这种方法对玻璃体视网膜手术和其他眼内手术（如囊切开术和白内障手术）的适用性，包括组织学分析、扫描电子显微镜和生理学测试。

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.