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If you have a refractive error, such as nearsightedness (myopia), farsightedness (hyperopia), astigmatism or presbyopia, refractive surgery is a method for correcting or improving your vision.
There are various surgical procedures for correcting or adjusting your eye's focusing ability by reshaping the cornea, or clear, round dome at the front of your eye. Other procedures involve implanting a lens inside your eye. Corneal procedures include incisional, LASIK, SMILE, lamellar implantation, corneal collagen shrinkage, and collagen crosslinking techniques.
Intraocular refractive procedures include phakic intraocular lens implantation and Refractive lens exchange with implantation of a monofocal, toric, multifocal, or accommodative IOL.
There is no universally-accepted, best method for correcting refractive errors. The best option for you should be decided after a thorough examination and discussion with your ophthalmologist. If you are considering refractive surgery, you and your ophthalmologist can discuss your lifestyle and vision needs to determine the most appropriate procedure for you.
The most widely performed type of refractive surgery is LASIK (laser-assisted in situ keratomileusis), where a laser is used to reshape the cornea.
Refractive surgery might be a good option for you if you:
a. Want to decrease your dependence on glasses or contact lenses;
b. Are free of eye disease;
c. Accept the inherent risks and potential side effects of the procedure;
d. Understand that you could still need glasses or contacts after the procedure to achieve your best vision;
e. Have an appropriate refractive error.
· Phakic Intraocular Lens (ICL / IPCL) Implantation
· Refractive Lens Exchange
· Photorefractive keratectomy (PRK)
· Radial keratotomy (RK)
· Astigmatic keratotomy (AK)
· Automated lamellar keratoplasty (ALK)
· Laser thermal keratoplasty (LTK)
· Conductive keratoplasty (CK)
· Intracorneal ring (Intacs)
· Laser-subepithelial keratomileusis (LASEK)
LASIK is a surgical procedure that uses a laser to correct nearsightedness, farsightedness, and/or astigmatism. In LASIK, a thin flap in the cornea is created using either a microkeratome blade or a femtosecond laser. The surgeon folds back the flap, then removes some corneal tissue underneath using an excimer laser. The flap is then laid back in place, covering the area where the corneal tissue was removed. With nearsighted people, the goal of LASIK is to flatten the too-steep cornea; with farsighted people, a steeper cornea is desired. LASIK can also correct astigmatism by smoothing an irregular cornea into a more normal shape.
Phakic IOLs (intraocular lenses) are an alternative to LASIK and PRK eye surgery for correcting moderate to severe myopia (nearsightedness), and in some cases produce better and more predictable vision outcomes than laser refractive surgery.
Phakic IOLs are clear implantable lenses that are surgically placed either between the cornea and the iris (the colored portion of your eye) or just behind the iris, without removing your natural lens. Phakic lenses enable light to focus properly on the retina for clearer vision without corrective eyewear.
Implantable lenses function like contact lenses to correct nearsightedness. The difference is that phakic IOLs work from within your eye instead of sitting on the surface of your eye.
Unlike contact lenses, you can't feel a phakic intraocular lens in your eye (much like you don't feel a dental filling for a cavity) and, apart from regular eye exams, phakic IOLs typically do not require any maintenance.
Refractive Lens Exchange, also called lens replacement surgery or clear lens extraction, may be a better option than LASIK, PRK or phakic IOL refractive surgery for people with presbyopia and high hyperopia (farsightedness).
It replaces your eye's clear natural lens with an artificial intraocular lens (IOL) to correct your refractive error and achieve sharper focus, reducing your need for reading glasses or bifocals.
Refractive lens exchange typically is for people with presbyopia or extreme shortsightedness & farsightedness, for whom LASIK, PRK or phakic IOL surgery generally are not suitable. If you have both presbyopia and moderate to severe hyperopia, RLE may be the only viable option for clear vision and minimal reliance on glasses after refractive surgery.
The procedure for refractive lens exchange is virtually identical to cataract surgery. The difference is that in RLE, the lens being replaced is clear, rather than a cloudy lens due to a cataract. As in cataract surgery, different types of lenses are available to replace your natural lens, depending on your vision needs and the health of your eyes.
Bioptics: In refractive surgery, the cornea will always remain the limiting factor for the correction of higher degrees of refractive error. The thickness, the keratometry, and the biomechanical properties of the cornea all have their influence on the final refractive outcome. It is of the utmost importance to avoid glare and halos by choosing large enough optical zones and respecting the mesopic pupil. In addition, to improve quality of vision, we must respect the characteristics of the cornea.
For these reasons, bioptics is a powerful tool in the correction of high levels of ametropia. Combined phakic IOL implantation and LASIK allows the application of the maximal optical zones for both modalities.