[♪ INTRO]
Eyes are amazing!
Think about it: People with sight rely on
two balls of clear jelly to focus light on
some special cells and create the whole experience
of vision.
And for two balls of jelly, eyes are surprisingly
robust—you get one set of them, and they
generally last your whole life.
But sometimes, they don’t work perfectly,
so these days, many people turn to laser eye
surgery—like Lasik and cataract removal—to
repair their vision.
I mean, I’ve done it!
And if it’s ever struck you as bizarre that
millions of people have signed up to have
a surgeon shoot lasers into their eyeballs—well,
yes.
But, it’s all thanks to the history behind
these procedures that they’re as successful
and common as they are today.
When eyes fail, it’s often because something
about the shape of the eye
is preventing light from focusing perfectly.
Like, if your eye is too long or too short,
or if the curve of the cornea—that clear
part at the front of your eye—isn’t just
right,
light can get focused onto the wrong spot.
That makes people nearsighted or farsighted—or
causes astigmatism.
These are often problems glasses can fix—but
eventually,
doctors began looking for more permanent solutions.
And that’s how lasers entered the game.
Back in the 1970s and ’80s, lasers were
improving dramatically and
transforming all sorts of science.
One of the really big inventions of the time
was something called the excimer laser, a
really precise type of laser that was originally
used for physics and chemistry research.
But eventually, ophthalmologists realized
that maybe they could use this laser, too…
to perfect people’s vision.
At the time, many of them were using a technique
called radial keratotomy to surgically improve
the vision of nearsighted people.
The modern form of this surgery had been refined
and made popular by the Soviet ophthalmologist
Svyatoslav Fyodorov, who would cut slices
in the cornea
that looked like the spokes of a wheel.
This flattened the cornea, which moved back
the focal point of light and corrected nearsightedness.
And for many patients, that worked pretty
well!
But there were also some issues.
Like, often, the cornea would keep getting
flatter over time, so people who started out
nearsighted would end up farsighted after
a few years… and then need glasses again.
Plus, using a blade on such delicate tissue
was risky
and depended heavily on the skill of the surgeon.
But excimer lasers are extremely precise and
controllable.
So, the idea behind the surgery was this:
You’d first carefully cut a flap in the
top layer of the cornea, then lift it back,
revealing the inner part.
Next, using the laser, you’d vaporize parts
of the cornea to achieve the desired shape.
Once that was done, you’d just put the flap
of cornea back on top, let it heal, and end
up with a new and improved eye.
Today, that’s known as Lasik eye surgery,
a process that hundreds of thousands of people
still get every year!
Compared to older methods, the laser was easier
to standardize, and the results were much
more stable, so it became the procedure of
choice for ophthalmologists everywhere.
But this wasn’t the end-all solution for
blurry vision—especially because, no matter
how well you can shape the cornea, that doesn’t
help if the lens beneath it is cloudy.
As we age, proteins in the lens of our eyes
naturally start to clump up
and create cataracts, which cloud the lens.
They’re entirely normal, but they can make
it hard to see
and cause blindness if they go untreated.
Scientists did have a way of breaking up cataracts
at the time—they’d use a tiny needle with
a vibrating tip to break up the lens before
sucking it out of the eye.
But unfortunately, the constant, rapid in-and-out
motion built up heat quickly,
and sometimes it burned the cornea.
So surgeons had to—and still have to—be
very careful with this method.
Then, around the same time that people began
putting their eyes under the laser for Lasik-type
surgeries, the ophthalmologist and inventor
Patricia Bath wondered if excimer lasers could
also be applied to cataracts.
The light from these lasers is so high-energy
that it vaporizes tissue without heating it
up, and Bath thought it could potentially
break up cataracts
without the risk of burning surrounding tissues.
Over five years, she developed a device called
the Laserphaco Probe, which became an extremely
safe and effective tool for breaking up cataracts
in the lens.
The method involves pushing a small needle
embedded with a fiber-optic cable and a tiny
vacuum through the side of the eye.
Then, surgeons shoot an excimer laser through
the cable directly onto the lens to break
it up, before sucking it out with the vacuum.
Finally, they insert a new, artificial lens
made of durable, clear plastic.
When Bath patented the probe in 1988, she
became the first Black woman to
hold a patent for a medical device.
Her invention significantly lowered the risk
of complications,
and it was adopted around the world.
Since then, technology has continued to advance.
Some surgeons have refined an older practice
of using ultrasound to break up cataracts,
while others have begun using the smaller
femtosecond laser in place of the excimer laser.
Still, the general concept—of using
a laser to break up cataracts—remains one
of the most widely-used technologies for extracting
cataracts around the world.
Since their invention, lasers have remained
a major player in medicine as scientists try
to keep up with the challenge of keeping our
eyes clear, healthy, and focusing.
And with hordes of people putting their eyes
under surgeons’ lasers every year, laser
eye procedures are some of the most common
and successful surgeries in the modern world.
Thanks for watching this episode of SciShow!
If you liked it, and if you’re curious about
what exactly surgeons are shooting lasers
into, you might enjoy our episode about what
eyes are made of.
You can watch that right after this!
[♪ OUTRO]
