Laser Vision Corrective Surgery

Laser vision corrective surgery is the most common form of refractive surgery. The goal of refractive surgery is to treat myopia, hyperopia, and/or astigmatism to decrease or eliminate a patient's dependence on glasses or contact lenses. Modern laser vision correction is performed with the use of a highly advanced laser known as an excimer laser. LASIK(laser-assisted in situ keratomileusis), the most commonly performed procedure, utilizes the excimer laser. This laser beam application results in a process called photoablation. In this process the treated corneal tissue absorbs the laser energy. Photoablation, in a very simplified way, can be thought of as "vaporization" the tissue. Because of the nature of the laser beam, only the tissue treated is removed. The tissue immediately adjacent to it is basically undisturbed. You may have heard of different types of laser refractive surgeries like PRK, LASIK, LASEK, Epi-LASIK, Advanced Surface Treatment, etc. However, there are really only 2 basic types of procedures. And they both use the excimer laser.

There are 2 basic types of excimer laser surgery. Let's look at both of them.

PHOTOREFRACTIVE KERATECTOMY (PRK)

PRK was the first type of excimer laser surgery to be performed. LASEK, Epi-LASIK, and Advanced Surface Treatment are different variations of this "no flap" technique. The laser beam is applied to the outer surface of the cornea which has been anesthetized with drops. This is done while you are comfortably lying down and looking upward. The size and duration of the laser beam application are controlled by a computer system. The surgeon enters the necessary data from your eye examination done beforehand, and the laser is then programmed to do what is appropriate for your individual correction needs. The laser beam effectively removes corneal tissue and makes the center of the cornea thinner for correction of nearsightedness or thinner in the periphery for farsighted correction.

Nearsightedness or farsightedness is reduced or eliminated because the cornea, which is really a lens, has had its power changed. This, therefore, causes the light entering the eye to be refocused directly upon the retina rather than at some other position. PRK also requires only a very short time to perform. Because of some generalized haziness of the cornea afterwards, there may be some degree of blurring for a few weeks. PRK is also painless to perform, and there is usually little discomfort afterwards. No patches are used although a temporary (1 or 2 day) soft contact lens is typically placed on the eye after treatment to function as a bandage for the cornea. Eye drops on a tapering dosage schedule are typically required for a few months after PRK. The long-term visual results after PRK are very good and equivalent to LASIK. PRK is also used for those patients who may have certain types of corneal surface diseases in which LASIK is not appropriate.

LASIK

LASIK stands for Laser ASsisted In situ Keratomileusis. It has many of the similarities of PRK in that it uses the same laser to accomplish the removal of corneal tissue. The major difference is that LASIK begins by the surgeon creating a very thin flap of the outer corneal membrane as seen below. An instrument is placed on the outer surface of the anesthetized eye, and the flap of cornea is cut as shown below.

The flap itself is not removed entirely. It remains attached at one end where it is "hinged" so that it can be simply folded back, out of the way while the excimer laser beam is then applied to the subsurface corneal tissue.

Once this is done, the flap is gently repositioned back into place where it will reattach itself in a short period of time. Unlike PRK, which requires the use of a temporary soft contact lens as a bandage for a few days afterwards, LASIK has its own "built-in" bandage, the flap of surface tissue. Patches are not needed. Both eyes can be done at the same time with LASIK, although individual situations might vary in this regard. Generally, the visual restoration with LASIK is faster than with PRK, and there tends to be less haziness of the corneas than with PRK.

Now, the really exciting news:

Until July, 2003, the Visx excimer laser was capable of correcting only those so-called lower order aberrations of the eye, namely nearsightedness, farsightedness and astigmatism, the 3 basic refractive errors. The real eye, however, often has what is called higher order aberrations. These are various sources of light distortion that may be found in other parts of the eye, not just the cornea. They can result in vision that is not as clear as one might like in spite of a full correction of all the refractive errors. Following extended research, the new STAR S4 IR® laser has been coupled with a WaveScan WaveFront® System so that these other aberrations of the eye may be corrected as well. This process incorporates this new dimension of measurement known as wavefront technology. Each eye is individually scanned for other types of aberrations besides the usual refractive errors. Once programmed into the laser, it has resulted in a dramatic increase in predictability and has brought visual improvement to a previously unprecedented level. A recent study evaluated and approved by the U.S. Food and Drug Administration showed that 98% of patients who were eligible and treated with the Advanced CustomVue treatment obtained 20/20 vision without glasses. While not every eye is a candidate for this type of treatment, we are now evaluating each eligible patient with the WaveScan WaveFront® System and treating those patients with Advanced CustomVue customized LASIK.

In our office, Advanced CustomVue LASIK is the procedure of choice in most cases to provide the kind of freedom from dependence on glasses or contact lenses that so many of our patients desire. We invite you to ask us if you are a candidate. We will be happy to evaluate your eyes to see if you are a candidate for these exciting procedures.

If you are considering laser refractive surgery, you should have some idea of those factors which make you a good candidate:

1. First on the list is knowing what can be accomplished by LASIK and PRK and what cannot. Refractive surgery has the goal of allowing light rays to be focused on the retina without the need for supplemental lenses (glasses or contacts). Thus, it simulates what glasses or contacts can do. If you have excellent vision with glasses or contacts, then LASIK may help you achieve that same clear vision without the need for glasses or contacts (or at least with much less of a need). If glasses or contacts cannot give you clear vision under any circumstances, then LASIK will not either. That is, if you have poor vision for some medical problem such as cataract, glaucoma, or a lazy eye, this surgery will not help you.

2. Second, you must have a stable eyeglass prescription that has not changed to any significant extent in the prior two years. You should be at least 20 years of age or older (younger patients often have prescriptions that have not yet stabilized).

3. Third, there are certain medical conditions of the eye and the whole body which restrict the performance of this surgery. These include Type 1 diabetes, certain auto-immune diseases such as rheumatoid arthritis and lupus erythematosus. If you are pregnant, have certain forms of glaucoma, have certain corneal diseases such as keratoconus or take certain medications such as amiodarone or sumatryptin, refractive surgery would not be an option for you. This list here, of course, is not complete. When discussing LASIK with your doctor, you should mention every medication that you are taking.

4. Fourth, if you are over age 40 and either wear bifocals, separate reading glasses or simply must remove your distance glasses to read up close, you will have a significant change in your "visual lifestyle." Remember that the surgery simulates the effect of distance vision glasses. If you cannot read up close with your distance glasses on, then after the surgery you will not be able to read up close without having to put on a pair of reading glasses. If you wear contacts for distance and put on reading glasses over the contacts, you will still be wearing the reading glasses after the surgery, but without having the contacts on. In some situations, a technique known as monovision, sometimes called blended vision, may be employed surgically. That involves fully correcting one eye for distance but leaving the other eye still nearsighted enough to permit reading up close. It means one eye for distance, one for close up. This idea, if applicable to you, should be discussed in detail with your doctor.

Once a decision is made to have the surgery, the choice of exactly which procedure must be made on an individual basis.

If you ordinarily wear contact lenses, in order to obtain an accurate assessment of your eyes, it is imperative that you discontinue wearing your lenses prior to your eye evaluation. Hard or gas-permeable contacts should be left out for three full weeks before the exam. Soft lenses need only be out for a week.

THE SURGERY ITSELF

After you have completed the outpatient registration, you may be given a very mild sedative before entering the laser treatment room. You will then be lying down in a comfortable position. Your eyes will be numbed with some eye drops (there are no injections used in these procedures), and a sterile draping will be placed over the eye having the surgery. A small device known as a speculum is then placed between the eyelids to help you keep them open. You will be instructed to constantly look at a small blinking light which serves as a "target" to look at. The next step involves the placement of the microkeratome on the eye. This is done to prepare the flap (for LASIK) or to prepare the corneal surface (for Epi-LASIK). this part takes only seconds to accomplish. Once the microkeratome is removed, you will be able to see the blinking light again. The laser itself will then be turned on for a predetermined period of time, usually only seconds). You will hear a series of repeated snapping sounds (but no pain) during the seconds of time required for the laser to remove the appropriate amount of tissue. When this phase is done, the surgeon will gently replace the LASIK flap by "floating" it into position or, in the case of Epi-LASIK, place cold sterile water on the surface to reduce postoperative discomfort. LASIK flaps adhere by themselves; no stitches are used. With Epi-LASIK, since there is no flap, the surface of the cornea is temporarily covered with a soft contact lens which acts as a bandage. When completed, the draping is removed, and the procedure is finished. For protection, a shield or goggles will be placed over the eye(s) after LASIK. No patches are needed. You will be given some eye drops to take home along with some simple instructions for care and for follow-up in your doctor's office.

Following the surgery, you may note some burning or other mild discomfort. There is usually no need for any strong pain relievers although these may be prescribed to have on a stand-by basis if needed. Typically the vision immediately after the LASIK is blurry, but most patients find that by the next day the vision is amazingly clear without glasses. Complete visual recovery after Epi-LASIK or PRK is somewhat slower. You might notice other side effects during the first few weeks afterwards such as increased light sensitivity, glare, halos around lights, especially at night, or hazy or blurred vision. You will need to be cautious for the first two weeks after your LASIK surgery to avoid getting swimming pool or hot tub water in your eyes. You will need to strictly avoid any type of rubbing of your eyes as the flap might become dislodged. The wearing of protective eye shields or goggles while you sleep at night is mandatory for a number of days afterwards, and your doctor will inform you of this.

We are certainly happy to discuss the various options with you if you are interested in refractive surgery. To make appropriate suggestions, we must first evaluate your eyes and medical status. The experience of being able to see without the glasses or contact lenses which have been a necessity for so much of your life is quite thrilling. Call us and find out.

Refractive surgery, such as LASIK and Epi-LASIK, is generally considered cosmetic surgery. As such, most insurance plans do not cover it although some plans may offer partial coverage. That is something you should determine beforehand. There are companies which offer refractive surgery financing, and our staff can help you in that regard.

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