Refractive Eye Surgery is any eye surgery used to improve the refractive state of the eye and decrease or eliminate dependency on glasses or contact lenses. This can include various methods of surgical remodeling of the cornea or cataract surgery. The most common methods today use excimer lasers to reshape the curvature of the cornea. Successful refractive eye surgery can reduce or cure common vision disorders such as myopia (near sightedness), hyperopia (farsightedness) presbyopia (aging eye) and astigmatism (eye defect in which vision gets blurred), as well as degenerative disorders like keratoconus (cornea in conical shape). The most widely performed type of refractive surgery is LASIK (laser-assisted in situ keratomileusis), where a laser is used to reshape the cornea. For people who are nearsighted, certain refractive surgery techniques will reduce the curvature of a cornea that is too steep so that the eye’s focusing power is lessened. Images that are focused in front of the retina, due to a longer eye or steep corneal curve, are pushed closer to or directly onto the retina following surgery. Farsighted people will have refractive surgery procedures that achieve a steeper cornea to increase the eye’s focusing power. Images that are focused beyond the retina, due to a short eye or flat cornea, will be pulled closer to or directly onto the retina after surgery. Astigmatism can be corrected with refractive surgery techniques that selectively reshape portions of an irregular cornea to make it smooth and symmetrical. The result is that images focus clearly on the retina rather than being distorted due to light scattering through an irregularly shaped 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) Understand that you could still need glasses or contacts after the procedure to achieve your best vision
d) Have an appropriate refractive error
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 eye doctor can discuss your lifestyle and vision needs to determine the most appropriate procedure for you.
Laser-assisted in situ Keratomileusis (LASIK): The surgeon uses either a microkeratome (precision surgical instrument) or a femtosecond laser (type of laser) to cut a flap of the corneal tissue (usually with a thickness of 100–180 micrometers). The flap is lifted like a hinged door, but in contrast to ALK, the targeted tissue is removed from the corneal stroma with an excimer laser. The flap is subsequently replaced. When the flap is created using an IntraLase brand femtosecond laser, the method is called IntraLASIK; other femtosecond lasers such as the Ziemer create a flap similarly.
2) Surface Procedures-.
Photorefractive Keratectomy (PRK)- is an outpatient procedure generally performed with local anesthetic eye drops. It is a type of refractive surgery which reshapes the cornea by removing microscopic amounts of tissue from the corneal stroma, using a computer-controlled beam of light (excimer laser). The difference from LASIK is that the top layer of the epithelium is removed (and a bandage contact lens is used), so no flap is created. Recovery time is longer with PRK than with LASIK, though the final outcome (after 3 months) is about the same (very good).
Transepithelial Photorefractive Keratectomy (TransPRK)- is a laser-assisted eye surgery to correct refraction errors of human eye cornea. It employs excimer laser to ablate outer layer of cornea, epithelium, as well its connective tissue, stroma, to correct eye optical power.
Radial Keratotomy (RK)- developed by Russian ophthalmologist Svyatoslav Fyodorov in 1974, uses spoke-shaped incisions, always made with a diamond knife, to alter the shape of the cornea and reduce myopia or astigmatism; this technique is in medium to high diopters, usually replaced by other refractive methods.