S a computer graphics
specialist, Brian A. Barsky has conjured up intricately
rendered worlds on a PC screen. But in the real world, he has
trouble seeing in the dark, and occasionally in broad
daylight. For the last 27 years, Dr. Barsky, a professor of
computer science and an affiliate professor of optometry at
the University of California at Berkeley, has suffered from
keratoconus, an abnormal thinning of the cornea that can wreak
havoc with depth perception and night vision.
For years, Dr. Barsky sought a remedy for his vision
problems. Then, while on sabbatical in 1992, he realized that
a solution for keratoconus patients might be found in the
complex algorithms of computer graphics.
An early teacher of computer graphics imaging technology
whose students have gone on to work for Pixar Animation
Studios and for Lucas Digital's Industrial Light and Magic,
Dr. Barsky has devoted much of his professional life to the
study of splines, the algorithms that are used to render
curved surfaces on computer screens. Spline mathematics
subdivides complex computerized shapes into smaller component
pieces, with each piece defined by its own equation. Dr.
Barsky figured out how to use splines to create a highly
detailed digital template of the human cornea. Using this
optometric blueprint, he created custom-designed contact
lenses.
Conventional contact lenses have simple shapes and are
usually symmetrical: they cannot account for irregularities in
the cornea's shape. Dr. Barsky's custom-made contact lens fits
precisely over an abnormally shaped cornea.
By using a common eye measurement instrument called a
corneal topography device with the same spline equations that
are used to create cinematic special effects, doctors could
one day measure the cornea's surface down to the tiniest
micron. Maps based on the measurements could be used to create
customized contact lenses for people suffering from
keratoconus, eliminating the need for invasive surgery.
"Normally with corneal topography, if I move my eye, the
measurements will change, which is incorrect, since my eye did
not really change shape," said Dr. Barsky, who is talking with
contact lens companies that are interested in his invention.
"If we take that same input and run it though our more
sophisticated mathematical approach, we'll get a more accurate
profile of the cornea. The measurements remain the same even
for different gaze directions."
Lens makers are optimistic. "Dr. Barsky is at the center of
a turning point in our industry," said William E. Meyers, vice
president for science and technology at Paragon Vision
Sciences, a contact lens company in Mesa, Ariz. "For years, we
have speculated about how to design contact lenses to manage
the wide array of clinically observed corneal distortions. Not
only does Dr. Barsky deliver the math, but he pursues the goal
with the passion of a man whose own vision is challenged by
just such an ocular complication."
Dr. Barsky's spline-based model could also improve the
accuracy of Lasik surgery, in which part of the cornea is cut
and peeled back and the underlying tissue is reshaped by a
laser. People whose eyes are unsuitable for Intacs, tiny
crescent-shaped inserts that are implanted in the cornea to
flatten the curvature and correct nearsightedness, could also
benefit, as could those with eye ailments like
astigmatism.
Dr. Brian Boxer Wachler, director of the Laser Refractive
Center at the Jules Stein Eye Institute at the University of
California at Los Angeles, said the spline-based design could
be useful to people who must wear contact lenses but cautioned
that such specialized lenses could be too expensive to
manufacture. "That could be the edge on the double-edged
sword," Dr. Boxer Wachler said. "If you have to make a special
lens for each eye, it's a lot more expensive, versus using a
standard lathe that produces uniform lenses."
But Dr. Barsky is convinced that the market is large enough
— nearly one million Americans suffer from corneal
abnormalities — to support a custom-made lens industry. "Most
people buy contact lenses for cosmetic or convenience
purposes," he said. "This is important for those who need
lenses that are medically necessary as the only hope to
provide good vision and avoid a corneal
transplant."