Ophthalmology

Pulsed Electron Avalanche Knife


Cut in the human retina produced by PEAK in-vitro (eye bank sample, cutting rate 1 mm/s).

Current mechanical approaches towards vitreoretinal surgery carry distinct risks including traction tears, excessive fibrovascular hemorrhage, and imprecise depth of cuts. Plasma-mediated dissection of tissue with short-pulsed (0.1 ps to 10 ns) lasers, while helping to reduce traction-related damage and improving cutting precision, carries its own set of risks and disadvantages. Light propagating beyond the focal point of the beam can be damaging to the retina. Large optical aberrations, for example while operating on peripheral retina, reduce the precision and safety of the procedure. Another approach to tractionless dissection in fluids involves application of pulsed shallow-penetrating lasers (Er:YAG and ArF excimer) delivered into the eye via optical fibers. Strong absorption of laser radiation in water or in tissue enables localized treatment with low threshold energy. However, these instruments did not achieve widespread acceptance in practice due to their prohibitively high cost, large size, and relatively slow pace.

Discharge on cylindrical microelectrode in saline driven by microsecond burst of pulses.

To address the disadvantages of both, the mechanical and the laser-based instrumentation in intraocular surgery, we have developed a device called Pulsed Electron Avalanche Knife (PEAK). This instrument uses high electric field rather than laser photons to create plasma in a close proximity to a microelectrode built into an intraocular probe, and thus it is compact and inexpensive. Optimized geometry of the electrode and temporal structure of the waveform allow for minimization of both, the thermal and mechanical damage zones. The instrument is capable of precise dissection of all ocular tissues and can be applied in vitreoretinal, cataract, and glaucoma surgery.


SEM micrograph of the lens capsule cut with PEAK. Note the sharpness of the edge - the scale bar is 10 μm.

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