Lightning Scalpel
It's one of the most delicate operations imaginable: An eye surgeon
excises a piece of membranous tissue next to a patient's retina that
threatens to damage or obscure the light-sensitive cells. Such
"vitreoretinal surgery" can save the vision of someone whose eyes have been
damaged by diabetes or trauma, but conventional microblades and
microscissors can tear fragile tissues, and attempts to use lasers haven't
succeeded. Researchers at Stanford believe they've developed a better
option-a needle-sized "plasma knife" that cuts via blasts of electricity.
The new knife, explains Stanford physicist Daniel Palanker, is a
tiny electrode that delivers electrical pulses a few nanoseconds long to
create "plasma streamers"-lightning-like discharges that slice through soft
wet tissues. Since the process doesn't require traction, as cutting with
blades does, the risk of tearing is reduced. The surgeon sets the cutting
depth and speed by adjusting pulse strength and duration. Mark Blumenkranz,
chair of the department of ophthalmology at Stanford University School of
Medicine, is helping test the plasma knife on rabbits; the researchers hope
to begin human trials by year's end. Eventually, Palanker says, the plasma
device could be used not only in vitreoretinal surgery but also to treat
conditions such as cataracts and glaucoma.
