| Other Monovision
questions:
If I choose
to have monovision, does that mean I will
never need reading glasses?
What will the vision be in
my reading eye with monovision?
I tried monovision with contacts
and didn't like it. Will it work better
with surgery?
How do you decide which eye
to do for distance and which for near?
How will monovision impact
my ability to perform in certain sports?
The use of one eye
for distance and one eye for near vision
is referred to as monovision and is one
of the options to consider as part of your
refractive surgery decision. Monovision
has been used successfully for over 20 years
with contact lens correction and with various
types of refractive surgery. By correcting
one eye to focus in the distance and one
eye to focus for near, the vision part of
our brain tends to suppress or filter out
the image from the eye that is not in clear
focus. The patient is not bothered by the
eye that is not in focus. We create monovision
using the laser such that the dominant eye
focuses at distance and the non-dominant
eye at near.
One of the best ways to define monovision
in the context of refractive surgery is
that you can aim to have each eye corrected
to a natural focus at any distance you choose.
How well it will see at other distances
depends upon how old you are. For example,
if you are 30 and we correct each eye to
excellent distance vision, then you will
have good vision at almost any distance
because, due to your young age, the eye
will be able to accommodate (adjust focus)
from far to near. If, on the other hand,
you are over 40 and we correct each eye
to excellent distance vision, you will not
see well at a typical reading distance and
will need reading or near vision glasses.
This change in accommodation (focusing ability)
will generally begin to be noticed about
age 40 and will usually get worse quite
rapidly over the next few years (presbyopia).
This loss of ability to change your focusing
distance from far to near will occur whether
or not you have refractive surgery.
At any age, if you have the vision in one
eye corrected to a natural focus for near
tasks such as reading, you will not see
clearly with it farther away as the ability
to change focus only goes from far to near.
The brain adjusts to each eye being focused
at a different distance within 6-8 weeks.
You do not need to consciously make any
adjustments.
There is no right or wrong answer to the
question of whether to have monovision.
This information is to help you make this
decision.
As a rule, we suggest against monovision
if you are under the age of 35 for two reasons:
1) It will be a number of years before you
will notice any benefit from it; and 2)
It is very possible that there will be a
better (or at least as good) surgical way
to help presbyopia by the time it is a problem
for you. We also generally recommend against
monovision at any age for people who may
need to see better than average for certain
tasks. Some examples might be pilots, race
car drivers, someone who drives for a living
(especially at night), and avid tennis players
(especially for playing at night).
In our experience, most people over the
age of 40 to 45 who try monovision and take
a few months to become accustomed to it,
like it and find it very useful. Those who
have monovision will be able to generally
see well enough both at distance and near
to do most things at any age without corrective
lenses. Depending on the exact result obtained
(as is true for everyone having refractive
surgery) there might still be some situations
when the very best vision or the maximum
visual comfort might require wearing glasses
(or possibly contacts). Night driving and
prolonged reading are two examples that
are mentioned frequently, but it could be
anything for which you feel the need or
desire to see the very best possible.
It is probably helpful to realize that
without a specific cure for presbyopia,
once you are past the 40 year age range,
all refractive corrections involve compromise.
If you have both eyes corrected for good
distance vision, you will need glasses for
close vision. If you have both eyes corrected
for close vision (not a common choice) you
will need glasses to clearly see everything
far away. If you choose monovision, although
your vision may work well for almost all
purposes, you might feel it is less than
perfect.
We know of no perfect way to help you make
this choice. We would suggest that if significant
doubt remains in your mind, that you aim
to have your vision corrected for good general
distance vision and plan to use reading
glasses when necessary.
It is important to note that if you choose
monovision and are unable to get used to
it, it can be reversed by performing an
"enhancement" procedure on the
eye left for near. Once the enhancement
is performed the near eye then sees more
clearly in the distance and reading glasses
are then required for all near tasks.
Below you will find the answers to frequently
asked questions about monovision. if you
have any further questions regarding your
care, please contact
us.
MONOVISION FREQUENTLY ASKED QUESTIONS
A: No. Presbyopia continues to worsen
as you get older, whether or not you have
monovision. At some point, the presbyopia
may be so bad that reading glasses will
be necessary. Still, there is a benefit
to having the monovision in that there won't
be a complete dependence on glasses for
things up close. Larger print will still
be readable without glasses, and things
slightly farther away (like computers and
dashboards of cars) will still be readable.
Without monovision, even these things would
be blurry without reading glasses. For this
reason, patients usually don't "give
up" their monovision as they get older.
They still read better with the monovision
than they would if both eyes are corrected
for distance, even though for certain things,
reading glasses become necessary.
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A: The distance vision in the eye
set for reading will be less than 20/20.
The reading eye is left slightly near sighted
to allow for better close vision. The amount
of residual nearsightedness may be different
for different patients, depending on age
at the time of surgery, how "good"
the patient wants the reading to be, how
much distance vision they are willing to
give up, and how long they want to be able
to read before they eventually need reading
glasses. Typically, the amount of near sightedness
left will be between -1.00 and -2.00 diopters.
On average it is -1.50 diopters. Regardless
of how many residual diopters of nearsightedness
are left to allow for the monovision, the
vision on the eyechart can NOT be predicted
just by looking at this number. There is
no conversion between diopters and visual
acuity on the eyechart (20/20, 20/30, etc.).
In other words, if you are left with -1.50
diopters of residual nearsightedness you
may see 20/40 with that eye in the distance,
or you may see 20/100, 20/80 or 20/50. We
cannot predict. It can be and is different
for different people. In any case, it is
not really important WHAT the distance vision
is in the reading eye. What IS important
is that with both eyes open you are able
to comfortably see both near and far for
most of your needs.
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A: It may, and it may not. Part of
it depends on how it was tried with the
contact lenses. Was it tried for a day,
or for a month or more? Sometimes it takes
awhile for the brain to "adjust"
to this way of seeing. Were the contact
lenses properly fit? Was the proper eye
set for distance? Was there any astigmatism
that needed to be corrected that wasn't
with the contacts? Even if everything was
done "right" there is certainly
a chance that monovision didn't work well.
Some of these people have gone on to have
surgery, and have tried monovision with
surgery and have liked it. Some still did
not like it, even with surgery. There may
be some contact lens problems that people
attribute to monovision problems, and that
is why some people may do well with it,
even if the contacts didn't work well.
In a random sample of patients who have
done monovision with surgery, 85% of patients
end up liking the monovision enough to keep
it. 15% decided to give it up and have the
reading eye set for distance. These 15%
of patients either disliked the monovision,
or felt the advantage of some reading ability
was not worth the distance tradeoffs.
Patients who tried monovision properly
with contacts and didn't like it will have
a higher than 15% chance that the monovision
with surgery will not be acceptable. It
may be a 50:50, or even 80:20 chance that
it won't work with surgery. However, if
you are strongly motivated to get monovision
to work for you, you may still want to try
monovision with surgery, even if it did
not work with contacts.
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A: There are several factors involved.
One is, which is the dominant eye? Usually,
but not always, the dominant eye is set
for distance. Sometimes a patient will come
in who has been wearing contacts for monovision
and the dominant eye is set for near. If
this has been done for awhile, and the patient
is doing well with the monovision, we will
keep it this way and correct the non-dominant
eye for distance. Some patients have a large
difference between the measurements in the
two eyes. One eye may be -4.oo diopters
and the other may be -8.00. Even if the
-8.00 diopter eye is the dominant eye, we
might make that the reading eye in order
to minimize the amount of treatment each
eye gets. Part of the purpose of the comprehensive
eye exam is to look at all of these issues
and decide what will work out best.
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A: It depends on the person and the
sport. Fast moving sports may be more affected
than slower sports. Racquetball, tennis,
baseball, motorcycle racing, and other fast
moving activities may be more difficult
with monovision because the depth perception
might be affected slightly. Slower sports
like golf, basketball, skiing and bicycling
may be less affected, though some people
may notice troubles with these sports with
monovision. Everyone is different.
If you choose to do monovision and have
problems with certain activities, the options
would then be to either have a retreatment,
give up the monovision and improve this
distance vision, or wear a contact lens
in the undercorrected monovision eye to
bring the two eyes into balance. I have
many patients who do this for a few hours
per week while playing tennis or racquetball,
then take the lens out and enjoy the reading
advantage monovision offers.
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