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Daniel V. Palanker, Jason M. Miller, Michael F. Marmor, Steven R. Sanislo, Philip Huie, Mark S. Blumenkranz; Pulsed Electron Avalanche Knife (PEAK) for Intraocular Surgery. Invest. Ophthalmol. Vis. Sci. 2001;42(11):2673-2678.
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purpose. To develop a better and more economical instrument for precise,
tractionless, “cold” cutting during intraocular surgery. The use of
highly localized electric fields rather than laser light as the means
of tissue dissection was investigated.
methods. A high electric field at the tip of a fine wire can, like
lasers, initiate plasma formation. Micrometer-length plasma streamers
are generated when an insulated 25 micron (μm) wire, exposed to
physiological medium at one end, is subjected to nanosecond electrical
pulses between 1 and 8 kV in magnitude. The explosive evaporation of
water in the vicinity of these streamers cuts soft tissue without heat
deposition into surrounding material (cold cutting). Streamers of
plasma and the dynamics of water evaporation were imaged using an
inverted microscope and fast flash photography. Cutting effectiveness
was evaluated on both polyacrylamide gels, on different tissues from
excised bovine eyes, and in vivo on rabbit retina. Standard histology
techniques were used to examine the tissue.
results. Electric pulses with energies between 150 and 670 μJ produced plasma
streamers in saline between 10 and 200 μm in length. Application of
electric discharges to dense (10%) polyacrylamide gels resulted in
fracturing of the gel without ejection of bulk material. In both dense
and softer (6%) gels, layer by layer shaving was possible with pulse
energy rather than number of pulses as the determinant of ultimate
cutting depth. The instrument made precise partial or full-thickness
cuts of retina, iris, lens, and lens capsule without any evidence of
thermal damage. Because different tissues require distinct energies for
dissection, tissue-selective cutting on complex structures can be
performed if the appropriate pulse energies are used; for example,
retina can be dissected without damage to the major retinal vessels.
conclusions. This instrument, called the Pulsed Electron Avalanche Knife (PEAK), can
quickly and precisely cut intraocular tissues without traction. The
small delivery probe and modest cost make it promising for many
ophthalmic applications, including retinal, cataract, and glaucoma
surgery. In addition, the instrument may be useful in nonophthalmic
procedures such as intravascular surgery and
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