What is refractive surgery?

Refractive surgery is ocular surgery which reduces a person's refractive error (eyeglass or contact lens prescription). Currently there are a number of different types of refractive surgery available. The type of surgery that is best for a patient depends on several factors including the magnitude of their refractive error (strength of their prescription), their age, and their visual needs and desires.

The eye has two optical elements, the cornea and the crystalline lens, which determine its power. The cornea is the outer window of the eye which covers the iris (the colored part of the eye). The cornea makes up two-thirds of the eye's power. Since it is located on the outer part of the eye it is easily accessible for surgical alteration. The crystalline lens is located inside the eye just behind the pupil. Current technology and surgical techniques has made removal and replacement of this lens a safe and successful procedure.

Most refractive surgeries change the shape of the cornea reducing the refractive error. The corneal shape is altered by either making incisions in the cornea which change its shape (radial keratotomy) or by reshaping the cornea by sculpting it with a laser (PRK and LASIK). Another type of refractive surgery removes the crystalline lens of the eye and replaces it with a plastic lens (refractive lensectomy).

What can refractive surgery do for me?

Refractive surgery can reduce a person's refractive error (prescription) thus reducing dependency on eyeglasses or contact lenses. A person considering refractive surgery needs to know, however, that refractive surgery does not always completely eliminate a person's prescription, and sometimes following refractive surgery a person must still use eyeglasses or contact lenses to see their very best.

What refractive surgery won't do for me?

Refractive surgery cannot eliminate all eye problems that require glasses or contact lenses. Presbyopia, a condition that results in decreased near vision from loss of focusing ability of the crystalline lens, is not correctable with refractive surgery. People who have presbyopia, which includes many people over 40 and most people over 50, can still have refractive surgery to correct their nearsightedness or farsightedness. Following surgery however, these people will need to wear reading glasses for near visual tasks.

Refractive surgery will not correct eye diseases such as glaucoma, cataracts, retinal diseases, dry eyes, and corneal diseases. In fact with some ocular diseases it is best not to consider refractive surgery since the procedure may aggravate the condition. Refractive surgery will also not prevent ocular diseases from developing at a later date nor will it prevent minor refractive changes from occurring as time passes.

Am I a candidate for refractive surgery?

This question has many variables and the best way to get an accurate answer to this question is to ask your eyecare professional. Optometric physicians are very qualified to give you an answer to this question and to guide you in selecting a skilled surgeon to perform the surgery. If you are a candidate for refractive surgery and choose to have surgery your optometric physician can perform your pre-surgical and post-surgical care.

Radial Keratotomy (RK)

 

In radial keratotomy incisions are placed in the peripheral cornea which weaken the peripheral cornea causing it to bow out slightly. This bowing flattens the central cornea resulting in a reduction of myopia (nearsightedness). Variations of this technique, astigmatic keratotomy (AK) reduces astigmatism and hyperopic keratotomy (HK) reduces hyperopia (farsightedness). Radial keratotomy is effective in reducing small and moderate amounts of myopia but is less effective with high myopia. Astigmatic keratotomy is effective for small and moderate amounts of astigmatism. Hyperopic keratotomy has shown variable success on small amounts of hyperopia and poor success with correcting moderate and high amounts of hyperopia.

An advantage of radial keratotomy is that it has a rapid recovery, especially with low myopia. A disadvantage of RK is that it weakens the peripheral cornea which can result in visual fluctuations following surgery. This weakening is more pronounced on higher amounts of pre-operative myopia.

 

Excimer Laser Photorefractive Keratectomy (PRK)

 

PRK is a relatively new procedure in the U.S. It utilizes a laser which has just recently been approved by the FDA. Since other countries are not subject to our FDA's jurisdiction, PRK has been performed successfully in other countries for several years.

The excimer laser is a high energy ultra-violet laser which vaporizes tissue. This vaporization allows the corneal tissue to be reshaped resulting in a reduction of refractive error. Although the excimer laser is used in other countries to reduce nearsightedness, farsightedness, and astigmatism, it is currently approved only for the treatment of nearsightedness in this country.

The procedure is performed by removing tissue from the surface of the central cornea with the laser. The removal of this tissue results in a flattening of the central corneal curvature which in turn reduces the myopia. PRK can be performed with success on small and moderate amounts of myopia. Its advantages include limited change in corneal strength which produces less long-term visual fluctuations than can be seen with RK. A disadvantage is that it has a long healing period (approximately six months).

 

Laser in-situ Keratomelieusis (LASIK)

 

LASIK also utilizes the excimer laser to change the shape of the cornea. In LASIK the surgeon creates a flap of corneal tissue exposing a layer of the cornea called the stroma. The laser is then used to reshape the corneal stroma, after which the flap of corneal tissue is carefully replaced over the top. Because of this flap technique the cornea heals quicker and results in faster recovery for the patient. Besides a quicker recovery LASIK will also correct higher amounts of nearsightedness than does RK or PRK. As with PRK, LASIK does not significantly alter the cornea strength.

LASIK is a newer procedure than is PRK, and has not been studied by the FDA. LASIK is considered an off-label use of the excimer laser which simply means that it has not been studied and approved by the FDA. It is very common for medical instruments to be used for off-label uses in medicine; such use is not done without study by the medical community however. LASIK has been performed in Canada, Europe, South America, Asia, and Australia for a number of years and has been found to be very safe and successful. A similar procedure, called Automated Lamellar Keratectomy (ALK), has been successfully performed in the U.S. for several years. ALK is very similar to LASIK, except it does not use the excimer laser to reshape the stroma.

 

Refractive Lensectomy (RL)

 

Refractive lensectomy is utilized to reduce nearsightedness and farsightedness. The procedure uses technology and techniques used in cataract surgery to remove the crystalline lens and replace it with an artificial plastic lens. By carefully choosing the power of the artificial lens the person's refractive error can be successfully reduced or eliminated.

 

Because refractive lensectomy removes the natural lens, the patient looses their ability to focus for near since the natural lens is responsible for near focusing. As time passes we all lose our near focusing ability. This condition, called presbyopia, occurs slowly and is first noticed by most people in their forties. By age fifty most people have lost a significant amount of their near focusing ability and must either wear bifocals or reading glasses. Since refractive lensectomy causes artificial presbyopia, this procedure is usually reserved for people who have already are presbyopic, in other words this procedure is usually done on persons over the age of fifty.

The Laser Centers

I am an affiliate of The Laser Centers (TLC) I would like to direct you to thier web pages for more information. www.lzr.com