Mackin: Let’s talk about 3D Lasik surgery. What exactly
is it?
Joel Hunter, MD: Lasik is an acronym that stands for
“laser-assisted in situ keratomileusis.” That’s a longwinded
way of saying doctors create a small flap in the
cornea,
which is a clear window of tissue on the front of
the
eye. Doctors lift that flap and use a laser to reshape
the
cornea, then they lay the flap back down. This takes
the
pain and recovery time out of the process.
It used to be that you’d laser the surface, which was
painful, and required several days to recover. Then it
took a couple of weeks to a couple of months for the
patient’s vision to fully return. Eventually we found out,
“Wow, we can just do this under this flap, and people
heal and see well pretty quickly.” Everybody liked that,
so there was a big boom in these surgeries in the late
1990’s and early 2000’s, and you started hearing a lot
about them, because they became really popular.
Mackin: So what’s 3D about the operation?
Hunter: As with any field, the technology advances, and
then you look back and realize things have changed so
much that you need a new name for what you’re talking
about. That’s what happened with 3D Lasik. The technology
we use to capture the images of the eye, the optics
inside
the eye—from the cornea to the lens to the retina—
seemed
far off
10 years ago. Now it’s
stuff
we can do in a
90-minute
appointment in the office.
We
can determine in
that time frame if people are candidates for surgery.
These 3D images are so high-resolution that they
show us what the optics are, as well as the health of
the eye, which helps us figure out who will do well and who probably won’t. And if you look at the happiness
rate for Lasik across tens of thousands of people,
about
95 percent of people say,
“Yeah,
I’d be happy to
do
it again.” But that means five percent wouldn’t.
And
really,
with how precise the technology’s
gotten,
that
figure should be even lower.
There should be pretty
close to 100 percent comfort with the surgery.
So
we’re
finding that a lot of people who responded negatively
were people who should have been screened out
by
using more advanced technology.
In respect to the actual laser itself, there was the
advancement from using a blade to using a laser. That
development has been implemented since around 2002,
and was a step forward. But the newest lasers, specifically
the WaveLight
Allegretto, can capture the threedimensional
curvature at the front of the eye. So if
somebody
has less curvature, we can program that in the
laser.
If somebody has more curvature, we can put that
in
the laser,
too. The laser’s
activity is based on specific
readings
of the eye. Your
eye is not like anybody else’s;
it’s
like a fingerprint.
So the laser reshapes the cornea based on the curvature
of your individual eye, and helps it keep its natural
shape better than older lasers did. That helps the eye
focus light better. It’s also part of the reason that glare
at night—halos and other things we used to worry
about—have decreased dramatically from previous
laser generations.
Mackin: Would you say, then, that 3D has just as much
to do with the diagnosis as with the actual procedure?
Hunter: Yes. The ocular coherence tomography (OCT)
machine, for instance, gives us a three-dimensional scan of the retina, down to four-thousandths of a millimeter.
Your retina is about 300 microns thick. The OCT lets us
detect subtle changes that might be there before somebody
ever notices a change in their vision. That’s
really
important
when you’re talking about doing an elective
surgical
procedure, because even if it’s
safe and effective,
people still need the best advice they can get to
make
the best decision possible.
Mackin: Who chooses this surgery?
Hunter: People who don’t want to wear glasses or contacts
because they’re near-sighted
or far-sighted
or have
an
astigmatism. A lot of people wear reading glasses
and
want to get out of wearing them. So they go through
this
whole exam process that helps us narrow down who
we
can and who we can’t.
Mackin: Why isn’t surgery effective for certain people?
Hunter: They may have little membranes on their retina,
tiny amounts of swelling in the retina, little congenital
anomalies that a person was born with that may or may
not change over time. If we see subtle changes in someone’s
retina, we want to know about that before surgery,
rather
than after.
The retina is kind of like film in a camera:
No matter how sharply you get the image focused,
if
the film’s
not good, then you won’t
get a good picture.
So if we detect subtle changes, we want people to
know
about them, as well as whether we think those
changes
may be progressive. We
can say,
“Here’s
all
this
information,” so you’ll know where your eyes are
headed
15 years down the road. Then you can decide if
surgery
is right for you.
We might tell some patients, “This probably isn’t the
right choice for you, because we know that your retina
doesn’t work well.” In those cases, we may dilate their
pupils and take basically a cross-sectional picture—
almost like a CAT scan.
There are two parts that play a role in letting your eyes
focus light: the cornea, which we talked about, and the
lens inside the eye. Everybody has a lens in their eyes.
We can now get the objective density measurement of
that lens, and the camera can tell us that the lens is scattering
20 percent of the light that hits it, or the lens is
scattering
15 percent of the light that hits it.
Those measurements
help us, especially with elderly people who
are
starting to notice, “Boy,
I just can’t
read no matter
how
good my glasses are,” or “I have trouble reading
subtitles
on a screen no matter what glasses I have.”
Before that stage of life comes—when people start to realize
they’re having changes that are consistent with
cataracts—there’s a stage of density in a person’s lens that
may be problematic, even if it is not necessarily noticeable.
People don’t
notice the little things so much, like
needing
more light to read the menu in a restaurant, but
those
things become really apparent when we do density measurements. We can even show the patient a picture:
“Here’s your lens and how dense it is, and how much light
it’s filtering, compared to this 30 year old’s lens.”
For some of these people, laser surgery works in the
short term. Then, a couple of years later, they’re noticing
the alteration is no longer helping them very much.
That’s
because the change inside the lens has started to
filter
and decrease the vision. So you’ve fixed the
patient’s
need for glasses, but his lens is still filtering
things
on the inside. That’s
why it’s
really helpful to
have
as much information as possible before going into
surgery,
so you can say to people, “Your
best choice
here
is probably to do nothing and wait a year or two or
three
or longer,
and then have lens surgery
when the
time
comes. That will fix the problem at its root, rather
than
mask it temporarily.”
Mackin: Is there surgery for the retina?
Hunter: Retina surgery is hard. It is its own specialty, just
as refractive surgery is its own specialty in ophthalmology.
Retina surgery,
in general, is rarely ever elective.
Retinal
tissue is neurosensory tissue. It’s
attached to your
brain
by your optic nerve. So it’s
very delicate surgery,
and
you want to make sure you have a clear benefit-vsrisk
ratio. Retina surgery
doesn’t
happen until people
have
pretty poor vision.
When we detect subclinical changes that don’t have
signs or symptoms, the answer is not always going to be
something surgical. Even if we find early macular
degeneration, there are different therapies, nutritional
therapies, and ongoing care that can be managed by a
specialist in those different fields. Vision correction by
way of retinal surgery generally only happens when
people have pretty significant visual dysfunction that
stems from retinal pathology or disease.
Mackin: During lens surgery, does the surgeon actually put
a new lens inside the eye?
Hunter: Yes. Cataract surgery is lens surgery, and it’s
probably one of the most common surgeries in the
world. It’s done when the lens becomes so cloudy that
the person can’t really see through it, no matter what
glasses he has. Through a couple of tiny incisions, doctors
can use ultrasound to remove the lens and then
replace
it with a new,
clear lens that’s
artificial. That
lens
is usually made of acrylic, and sometimes silicone.
If
we’ve noticed lens change in a patient, I have him
hold
off
on Lasik surgery.
I feel like he’s
going to get a
somewhat
temporary gain out of 3D Lasik, however,
because
we’re on the cusp of a new generation of lens
surgery.
The surgery
itself, the incisions and the break-
ing up of that lens inside the eye, will be done with a
laser, which will make the process even more precise.
Even more exciting is the fact that the new lenses we are
putting into people’s eyes are getting better and better every year. They allow people to see near and far, which
is something that is not possible after a person reaches his
mid-40’s and typically needs reading glasses. These new
lenses allow people to see in a way they couldn’t before.
With a lot of these patients I’ll say, “I’d hold off and see
where you are at in a year, and where the technology’s is
in a year.”
As lens technology improves, the age at which someone
would benefit from lens replacement is dropping
and
dropping and dropping. It used to be that the average
age of these patients was somewhere in the mid70s.
Now,
in some clinics, that age is dropping to the
mid-50s
because lens technology is so much better.
We’re
finding that people get enough benefit out of the
procedure
that it’s
worth doing lens surgery
earlier in
life.
It prevents the need for cataract surgery
later.
Mackin: How does the cornea get misshapen in the
first place?
Hunter: It’s not that the cornea necessarily becomes
misshapen over time, or that a person had a nice cornea
and now it’s gotten weird—although, that may be true in
cases involving genetic problems. In general, though,
when somebody is near-sighted or far-sighted or has an
astigmatism—because their eyeball is too long or too
short, or their lens is a little too powerful, or their
cornea is a too steep or flat—it’s been that way, usually,
since they were in elementary or middle school, when
they put on their first pair of glasses.
If somebody needs glasses, it’s because light isn’t focusing
correctly on his retina. Instead the light is focusing a
little
in front of the retina, or a little behind. If he has an
astigmatism,
the light is skewed on his retina. The
cornea—that
front, clear window—supplies two-thirds of
your
eye’s
focusing power,
so subtle changes to it make a
really
big difference
in how clearly the eye focuses.
When we’re dealing with laser vision correction, we can
create a precise focusing pattern on the retina by removing
a small amount of tissue. The same thing goes for
people
who wear reading glasses. We
can give those
people
their reading vision back using 3D Lasik to
reshape
their corneas in a way that allows them to see
their
cell phones without putting on reading glasses. So
whatever
the problem is with the optics of the eye,
much
of the time you can treat it just by fixing the shape
of
the cornea, which is customized for each person. If
somebody
comes in and is near-sighted—say,
a minus-3
cornea—that
might be a completely different
shape than
the
next person I see who’s
also a minus-3.
Mackin: Interesting. So even if a person’s lens has lost
flexibility, you can treat the cornea for that?
Hunter: There are a lot of people who can see down the
road with one eye, while the other eye is useless at a
distance and is only good for reading. So we blend vision. Think of stereo music. When audio engineers
pioneered stereo music, they had to figure out what
came out of each speaker and blend those sounds
together into the stereo music in your head. Experts
have been working to do that for the eyes, as well, for
people who have lost flexibility in their lenses. There is
a sweet spot you can create. About 99 percent of people
can actually learn to blend the vision of both eyes and
can see better in the distance and up close. It’s a neat
trick we’ve been able to make work for most people
who come here wearing reading glasses.
Mackin: What’s the trick? Is there some kind of exercise
they do?
Hunter: I compare it to going to live in Spain. For the
first couple of weeks you have to concentrate and use
your dictionary to try to figure out what people are saying,
but if you live there for a couple of months, you’re
going
to pick up the language and start speaking it. Your
brain
has the ability,
when it’s
being saturated, to adapt.
There’s
plasticity over time, for everybody,
and that’s
how
your brain learns new things. Every minute of
every
day your eyes are open, you’re learning, whether
you
intend to or not.
Blended vision takes a couple of months for most people.
And even with their brain figuring it out, they can
still
see everything. They just have a temptation to close
one
eye to see what’s
happening, and that temptation
goes
away over time, because the brain is learning to
see
better with both eyes open.
We have a program called RevitalVision. It’s a computer
program that essentially trains your brain to see better.
Studies showed the vision of people who used RevitalVision
improved by two lines on the eye chart: They
were
going from 20/30 to 20/20 vision, or from 20/40 to
20/25,
and their contrast sensitivity,
which is kind of the
real-world
measure—brown letters on a yellow menu—
improved
100 percent, on average.
We wondered if we gave this to people who were having
trouble blending, or who wanted to do it faster,
would
it help them with that ability? A lot of what we
do
is about getting the brain to process information. If
you
think about it, you don’t
really see with your eyes,
you
see with your brain. There’s
no screen in the head.
It’s
all about how neurons talk to each other,
and how
they
form new synapses to process information efficiently.
That work has been really promising.
In the RevitalVision program, which runs about twice a
week for 10 weeks, you sit in front of a computer screen
for about a half hour, and you hit a button as you watch
patterns form on the screen. It’s pretty boring. So people
who commit to it do really well.
Mackin: Without the computer, how can you learn to
blend your vision?
Hunter: The same way that you learn anything: Present your brain with a new stimulus,
and it neuro-adapts to it over time. The first time you drove a stick shift, the
first
time you swung a golf club or hit a tennis ball, your brain told your muscles
what
to do. But we’re finding that processing visual information is also a learned
process.
From the time you’re born until you’re two years old, your brain is learning
to see. Your
eyes send images back, while your brain learns to process those
images
more sharply and clearly over time.
Mackin: This is the same sort of new learning that occurs after surgery?
Hunter: Yes. What basically happens is somebody comes in and says, “Hey, I
hate my reading glasses,” and I say, “I believe you, because everybody hates
their reading glasses.” And then we do 3D Lasik on the person and, on day
one, we check their vision and find they can read 20/20 on the eye chart, and
can read really small print up close. I tell them, “You’re doing great. You can
see us any time, but we’ll see you back here in a month, no matter what.”
So we see them in a month, and in a month they say, “I can read and I can see
down the road, but I notice there’s a difference in the vision between my eyes.”
And I say, “That means you’re right on track. You will notice it less over the
next couple of months.” We see them again in two months—a total of three
months out of surgery—and, by that time, most people have forgotten about
vision change. They don’t really think about it any more, and there’s kind of a
neutrality. The eyes don’t interfere with each other; they’ve learned to process
the vision in a different way.
After that three-month period, the brain gets better and better and better at processing,
so people reach a point where not only do the eyes not interfere with
each
other,
they can actually see better both at a distance and up close. What’s
so
cool about this is that’s
what the brain wants
to do. It wants to process information
coming in from both eyes. Naturally,
your brain sees better with both
eyes
open than it can with either eye. That’s
the eventual goal.
Mackin: Are there situations in which you do surgery on only one eye?
Hunter: Sometimes a person happens to be born with what he needs in one eye,
so we’ll only have to do surgery on the other one. But for most people, surgery is
necessary in both eyes because you need a very, very precise difference in refractive
error between the two eyes. You
have to be dead on or they won’t
blend. It’s
not
common that you’d find someone who would only need surgery
in one eye.
My
father was one of those people: I only had to do surgery
on one of his eyes.
Mackin: What about performing surgery on people who, say, have Cerebral Palsy?
Hunter: We can do that because lasers track the eye at 400 times per second, so you
can still get precision when you’re hitting a moving target.
Mackin: What do you suggest for people you turn away from surgery?
Hunter: It’s as varied as the reasons we turn them away. Glaucoma, macular
degeneration or crossed eyes would be better handled by a subspecialist. But
there are also antioxidant dietary changes that someone with early macular
degeneration might benefit from, as well as different vitamin therapies that a
retina doctor might prescribe. If a person has glaucoma or progressive disease,
then their treatment could be taking an eye drop each night, as prescribed by a
glaucoma specialist. A big part of what we do with our 3D diagnosis is provide
people with information that helps them determine the best approach.
by Molly Mackin
Hunter Vision
Revital Vision
Excerpts from the Katie Leclerc Issue Aug/Sep 2011:
Mercy Ships — Healers on the High Seas
Silver Scorpion — New Breed of Superhero
Katie Leclerc — ABC Family Star and Ménière’s Disease
Paralympic Sailing — Harnessing the Wind
Funny Business — Sue Z. Hart
Lasik Surgery — The Eyes Have It
Ra'Shad Solomon — Model of Persistence
Articles in the Katie Leclerc Issue; Humor — Jockey: A Horse Tale (Pt. 2); Ashley Fiolek — The Wind Beneath Her Wheels; Sen. Tom Harkin — A Call to Employers; Lasik Surgery — The Eyes Have It; Funny Business — Sue Z. Hart and the Art of Laughter; Water skiing — Mama Does It Barefoot; Paralympic Sailing — Harnessing the Wind; Mercy Ships — Healers on the High Seas; Katie Leclerc — ABC Family Star on Ménière’s Disease; Silver Scorpion — New Breed of Superhero; Ra’Shad Solomon — Model of Persistence; Eating Local — A Four Seasons’ Palette; ABILITY's Crossword Puzzle; Events and Conferences... subscribe
