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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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- The word “phakic” describes the state of the eye that still has its
natural (crystalline) lens intact.
- A phakic IOL, sometimes known as an implantable contact lens (or ICL),
is used to treat high degrees of nearsightedness (myopia).
- Studies are ongoing to evaluate the treatment of farsightedness
(hyperopia) and astigmatism with the phakic IOL as well.
- The eye’s natural lens is not removed, so patients can retain their
pre-existing ability to focus.
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- Performed in a surgical suite.
- A light sedation is usually offered for anxiety.
- Entire procedure usually takes 10 to 20 minutes.
- Anesthetic eyedrops are instilled prior to surgery.
- A laser peripheral iridotomy (LPI) is performed prior to surgery to
ensure normal fluid flow inside the eye following phakic IOL insertion.
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- The procedure is performed using one of two methods:
- Method 1
- One or more small incisions are made at the junction of the sclera
(white part of the eye) and the cornea.
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- The phakic IOL is inserted onto the iris (the colored part of the eye).
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- The incision is repositioned with fine sutures.
- Sutures are finer than a human hair.
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- Method 2
- One or more small incisions are made at the junction of the sclera
(white part of the eye) and the cornea.
- The phakic IOL is inserted beneath the iris (the colored part of the
eye).
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- Once the lens is properly positioned inside the eye, it provides the
necessary correction to redirect light rays precisely onto the retina.
- Steroid and antibiotic eyedrops will need to be applied for about one
week following the surgery as your vision continues to improve.
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- May be recommended for patients with corneas too thin to safely perform
corneal refractive surgery (e.g., LASIK, PRK).
- May be recommended for patients with high degrees of refractive error or
significantly dry eyes.
- May result in less visual distortion (aberrations), such as glare and
halos, than corneal refractive surgery for a given refractive error.
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- In some cases, there is not enough room in the eye to accommodate the
lens.
- Your ophthalmologist (Eye M.D.) will take careful measurements to
ensure adequate space in the eye to allow safe placement of the phakic
IOL.
- Once the lens is inside the eye, repositioning or removal of the IOL may
be required if the lens is at risk of damaging any intraocular
structure.
- Presence of cataract.
- History of retinal detachment or other serious retinal disease.
- History of ocular inflammation.
- History of glaucoma.
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- Over-correction or under-correction (with a possible need for a
re-treatment).
- Because the phakic IOL comes into contact with the delicate structures
inside the eye, infection or inflammation may result after the IOL is
implanted.
- Haze and halo effect at night.
- Excessive tearing.
- Potential for increased intraocular pressure (IOP).
- Potential for retinal detachment.
- Cataract formation and corneal swelling (infrequent).
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- Advanced surgical procedures, including phakic IOL, are creating more
opportunities for people who want to be less dependent on glasses or
contacts.
- Refractive surgery may not totally 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/or side effects associated with your
particular 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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