A better vision
The LADARVision 4000 system
relies on laser radar (LADAR) technology originally developed to help NASA spacecraft
rendezvous and dock with satellites during service calls.
The tracking ability of
the laser radar system lent itself to LASIK eye surgery, which uses an excimer
laser to improve a patient's vision by physically reshaping the cornea. But
the human eye is in constant motion during the surgical procedure, making small,
involuntary movements at a rate of about 100 times per second. Eye tracking
devices are used to constantly sample the eye position at any given time during
the surgery.
In the 1980s, researchers
at Autonomous Technologies Corp. -- now a part of Alcon, Inc. in Fort Worth,
Texas -- developed the pointing and scanning laser beams that led to LADARVision
4000.
Today, the LASIK system
uses two lasers to perform a surgery. The first, an infrared laser, consistently
tracks the eye position about 4,000 times per second, about four times faster
than the speed needed to keep up with involuntary eye movements for a surgery.
The system's second laser then reshapes the cornea.
"The faster you go the more
robust your system, which cuts down on all kinds of error," said Gary Gray,
an associate technical director at Alcon, Inc.
Video-based eye-tracking
systems can typically follow eye movements between 60 and 250 times per second,
though the eye can move outside limits set by eye surgeons and require a halt
in the entire procedure until the laser can be centered again.
"In LADARVision 4000, [the
surgeon's] image of the eye doesn't move, it seems to be completely still,"
Gray said. Since the tracking laser keeps constant tabs on the eye movement,
the eye appears stabilized to the actual operating laser, he added.
Alcon researchers hope to
have an even newer system, the LADARVision 6000, ready by the end of the year.
The LADARVision 4000 system.
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