ELECTRICAL ALTERNATIVE LASERS INTRAOCULAR MICROSURGERY

Stanford University, Stanford CA

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Abstract

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.