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- Light rays enter the eye through the clear cornea, pupil and lens.
- These light rays are focused directly onto the retina, the
light-sensitive 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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- Inability to see clearly is often caused by refractive error.
- Four types of refractive error:
- Myopia (nearsightedness)
- Hyperopia (farsightedness)
- Astigmatism
- Presbyopia
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- In myopia (nearsightedness), there is too much optical power in the eye
- 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.
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- 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.
- In adults (but not children), distant objects will look clear, but close
objects will appear blurred.
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- 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.
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- Presbyopia is an age-related condition in which your eyes gradually lose
the ability to see things up close, because the lens of the aging eye
can no longer change shape.
- 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 begins to gradually decrease, making
it more difficult to see objects up close, unless the eye has
nearsightedness.
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- 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.
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- 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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- A non-laser procedure where the natural, non-cataractous, lens of the
eye is removed and replaced with an artificial, intraocular lens (IOL).
- The cornea is not reshaped.
- Used to treat moderate to high degrees of nearsightedness (myopia),
farsightedness (hyperopia) and patients who are not LASIK candidates.
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- The IOL is implanted in a surgical procedure and performed on an
outpatient basis under local or topical anesthesia.
- Procedure takes approximately 15-20 minutes.
- RLE procedure is exactly the same as routine cataract surgery.
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- In addition to a complete pre-operative eye exam, these measurements are
performed to give the surgeon the necessary information to calculate the
necessary power of the IOL:
- Keratometry: measurement of the form and curvature of the cornea.
- Retinal exam.
- The axial length of the eye from the cornea to the retina (A-scan).
- The depth of the anterior chamber.
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- After the eye is numbed with topical or local anesthesia, one to three
small incisions are made close to the edge of the cornea.
- After the procedure, these incisions are usually “self-sealing,”
requiring no stitches.
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- A tiny, high-frequency ultrasound instrument is inserted into the eye to
break up center of the eye’s natural, crystalline lens.
- The lens is then gently vacuumed out through this same instrument.
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- An IOL is folded and inserted through the same incision that was made to
extract the natural lens.
- The IOL is then unfolded and placed into the "capsular bag"
that originally surrounded the natural lens.
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- May be recommended for patients who have cataracts starting to form.
- May be recommended for patients with thin corneas who are otherwise not
candidates for the LASIK procedure.
- May be recommended for patients with unusually high refractive error.
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- Patients with significant ocular disease of any type.
- Patients with a history of retinal detachment.
- Patients with any reason for increased risk of infection.
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- Over-correction or under-correction (with a possible need for a
re-treatment).
- Infection.
- Increased floaters or retinal detachment.
- Dislocation of implant.
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- Advanced surgical procedures, including refractive lens exchange, 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.
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- 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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- 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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