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Question:
Can laser vision correction (LASIK) reduce or eliminate your
dependence on reading glasses and/or bifocals?
Answer:
ABSOLUTELY!
PRESBYOPIA
Presbyopia is the loss of the ability to accommodate.
Accommodation is the ability to focus up close. During middle
age, usually beginning in the 40s, people experience blurred vision
at near points, such as when reading, sewing or working at the
computer. There's no getting around it, this happens to everyone
at some point in life, even those who have never had a vision
problem before. Presbyopia is different from astigmatism, nearsightedness,
and farsightedness, which are related to the shape of the eyeball
and caused by genetic factors, disease, or trauma. Presbyopia
is the result of an age-related gradual loss of flexibility in
the natural lens inside the eye.
All of us have an adjustable lens inside of our
eyes that allows us to change our focus from distance to near
and vice and versa. This adjustable lens physically bends and
stretches inside our eyes, so that we can make the necessary focusing
adjustments. When we focus up close the lens bends and when we
focus far away the lens relaxes back to its neutral position (see
the illustrations below).
 
When
the eye views an object up close the lens bends to bring
the object into sharp focus |
When
the eye views an object at distance the lens stretches back
to its neutral position to bring the object into sharp focus |
Beginning
in our late teens and early 20’s, the natural lens inside
of our eyes begins to lose its flexibility. This decline in flexibility
continues into our late 50’s and early 60’s when it
plateaus. It is in our early to mid-40’s when we lose that
critical amount of flexibility required to focus up close, which
corresponds to the onset of presbyopia. If you are presbyopic,
you either need bifocals or a separate pair of reading glasses
to see what you normally could see up close when you were younger.
By the time you are 60, you will have lost essentially all of
your ability to focus closer than 3 feet. So, all close objects
will be blurred. When the eye views an object up close the
lens bends to bring the object into sharp focus. When the eye views
an object at distance the lens stretches back to its neutral position
to bring the object into sharp focus.
TREATMENT
Currently,
no treatments exist to restore the flexibility of the natural
lens. Using LASIK, however, we have developed a method of restoring
near vision while maintaining or even improving distance vision.
The LASIK technique for restoring near vision is called MONOVISION.
Monovision capitalizes on the brain’s dominance system.
In the same way that we have two hands and one hand is dominant,
we have two eyes and one eye is dominant. In the same way that
our dominant hand has a special function (i.e. it is the hand
that we write with and eat with), our dominant eye has a special
function. Our dominant eye is the eye that our brain preferentially
uses for viewing distant objects, and our non-dominant eye is
the eye that our brain preferentially uses for viewing near objects.
The concept of a dominant eye is easily demonstrated by the use
of a camera. When someone picks up a camera to take a picture,
they naturally bring the camera viewing lens up to their dominant
eye. With the Monovision LASIK procedure we correct the eyes so
that the dominant eye is corrected to focus clearly at distance
and the non-dominant eye is corrected to focus clearly at near.
Believe
it or not, the brain accepts this quite easily, because we utilize
our eyes independently for most of our life, depending on whether we are
performing a distance or near visual task. If both eyes are kept
open, our brain does not have the slightest idea which eye is
used for near and which one is for distance. All it knows is that
we see both distance and near. It is only when we close one eye
(which we generally do not do) that this disparity can be figured
out. There is a slight adaptation period, which usually only takes
2 to 8 weeks. Most depth perception is from the peripheral
vision. Since it is primarily central vision that is changed with
the LASIK Monovision procedure, depth perception is minimally
affected.
Because
each person has different visual needs, we attempt to vary the
amount of near correction to fit your specific situation. A golfer
may desire one eye to have clear vision at about three and one-half
feet (the distance of their tee). Computer personnel like their
vision at about two feet. People who do a lot of reading or knitting,
will prefer clear vision at 14-16 inches.
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