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Monovision for
Presbyopia
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How the eye works
• Light rays enter the eye through
the clear cornea, pupil and lens.
• These light rays are focused
directly onto the retina, the lightsensitive tissue lining the back of
the eye.
• The retina converts light rays into
impulses, sent through the optic
nerve to your brain, where they
are recognized as images.
• 70% of the eye's focusing power
comes from the cornea and 30%
from the lens.
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Refractive errors
• Inability to see clearly is often caused by refractive error.
• Four types of refractive error:
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Myopia (nearsightedness)
Hyperopia (farsightedness)
Astigmatism
Presbyopia
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Refractive errors: myopia
• The distance between the
cornea and the retina may be
too long or the power of the
cornea and the lens may be
too strong.
• Light rays focus in front of
the retina instead of on it.
• Close objects will look clear,
but distant objects will
appear blurred.
Myopia, or nearsightedness
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Refractive errors: hyperopia
• In hyperopia (farsightedness),
there is too little optical power.
• The distance between the
cornea and the retina may be
too short.
• Light rays are focused behind
the retina instead of on it.
Hyperopia, or farsightedness
• In adults (but not children),
distant objects will look clear,
but close objects will appear
blurred.
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Refractive errors: astigmatism
• In astigmatism, the cornea is
curved unevenly—shaped more
like a football than a basketball.
• Light passing through the
uneven cornea is focused in
two or more locations.
• Distant and close objects may
appear blurry.
Astigmatism occurs when light
passes through uneven cornea
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Refractive errors: presbyopia
• Presbyopia is a normal
condition in which your eyes
gradually lose the ability to
focus things up close.
• When we are young, the lens in
our eyes is flexible and is able
to change focus easily between
near and far objects, like an
autofocus on a camera.
• At around age 40, this flexibility
naturally begins to gradually
decrease, making it more
difficult to see objects up close.
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Non-surgical correction of presbyopia
• Presbyopia is often corrected
with reading glasses, bifocals
or contact lenses.
• People within the presbyopic
age who have good vision at
distance usually use reading
glasses for close-up vision
and remove them to see faraway objects.
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What is refractive surgery?
• A group of outpatient surgical procedures used to alter how your
eye focuses light rays on the retina, thereby improving vision and
reducing dependence on glasses and contact lenses.
• In most cases, refractive surgery affects the shape of your cornea
to redirect how light is focused onto the retina. Popular
procedures include LASIK, LASEK, PRK and CK.
Refractive surgery
procedure on the cornea
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What is refractive surgery?
• Most refractive surgery is performed on the cornea and affects
only the front of your eye, while the rest of your eye will change
naturally as you age.
• In some cases, refractive surgery procedures don’t reshape the
cornea; instead, the eye’s natural lens is either replaced or
enhanced by an implantable lens that helps correct vision.
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Monovision for presbyopia surgery
• Adjusting each eye for different focusing distances can reduce or
eliminate the need for glasses or contacts.
• Monovision, sometimes known as blended vision, allows for
different focusing distances in each eye separately.
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Monovision for presbyopia surgery
With monovision, one eye is
corrected surgically to allow
clear distance vision…
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Monovision for presbyopia surgery
…while the other eye is either
not treated, or is partially
treated, to allow clear vision
close up.
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Monovision for presbyopia surgery
• Monovision for presbyopia yields clear vision, one eye for distance
and one eye for near.
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Types of surgery
Monovision can be achieved through these types of surgery:
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Laser In Situ Keratomileusis (LASIK)
Epithelial Laser In Situ Keratomileusis (Epi-LASIK)
Photorefractive Keratectomy (PRK)
Laser Epithelial Keratomileusis (LASEK)
Conductive Keratoplasty (CK)
Phakic Intraocular Lenses (IOLs)
Refractive Lens Exchange (RLE)
Intrastromal Corneal Ring Segments (INTACS)
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Monovision for presbyopia surgery
• While the brain does get used to seeing with monovision, it can
take up to six to eight weeks for your eyes to adjust.
• It may be useful to try monovision with contact lenses before
having the monovision surgical procedure, as some patients may
not be good candidates for the surgery.
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Considerations for monovision for
presbyopia surgery
• Reduce or eliminate the need for both reading and driving glasses.
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Considerations against monovision
for presbyopia surgery
• May not be recommended for people needing to see better than
average and binocularly for certain activities at either distance or
near (like pilots).
• May not be recommended for people requiring rapid improvement
in vision, as it may take up to two months for your eyes to adjust to
monovision.
• Night driving vision may be more difficult since there can be
reduced depth perception.
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To be a candidate for monovision
surgery, you should…
• Be over over 40 years of age.
• Have an appropriate, stable refractive error within a correctable
range.
• Be free from eye disease.
• Understand and accept risks, limitations and side effects of the
procedure.
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Risks and possible side effects of
monovision for presbyopia surgery
• Infection.
• Over-correction or under-correction (with a possible need for a retreatment).
• Visual aberrations, such as seeing halos around lights at night.
• Lack of depth perception.
• Inability to adapt to the monovision state, possibly requiring a retreatment.
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Is refractive surgery right for you?
• Advanced surgical procedures, including monovision for
presbyopia, are creating more opportunities for people who want
to be less dependent on glasses or contacts.
• Surgery may not entirely eliminate your need for corrective lenses.
Glasses/contacts may still be needed for activities such as fine or
detailed work, reading and perhaps night driving.
• If an accommodating or multifocal IOL is used, then reading as
well as distance vision may be improved.
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Is refractive surgery right for you?
• A large part of the success of any refractive surgery depends on
your understanding of the procedure and your expectations.
• Since refractive surgery is an elective procedure, you have the
opportunity and responsibility to become fully informed about its
risks and benefits.
• Your ophthalmologist will explain the specific technique, its
benefits, as well as possible risks and side effects associated with
your case.
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Discuss options and questions with
your ophthalmologist
• With the help of your ophthalmologist, it’s ultimately your
responsibility to weigh the risks and side effects of a procedure
with the benefits it has to offer.
• If you decide refractive surgery is right for you, you may join
millions of people who have reduced their dependence on glasses
or contacts.
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