context: Three types of refractive surgery procedures are available. They include: Excimer laser procedures (including LASIK surgery, LASEK, and others) Artificial lens implants Cornea incision procedures and limbal relaxing incisions Developed in the 1980s, the excimer laser is computer controlled. It gives eye surgeons the ability to remove precise amounts of tissue from the cornea, allowing the cornea to be sculpted to achieve predictable changes in vision. This provides a high degree of safety and precision for laser-assisted procedures such as LASIK. LASIK is an abbreviation for "laser-assisted in situ keratomileusis." The steps of LASIK surgery include: Eye numbing drops are given before surgery to prevent pain. An eyelid holder keeps the eye open and prevents blinking. A suction ring is placed on the eye to keep the eye from moving and to lift and flatten the cornea. The eye surgeon creates a flap in the cornea. The surgeon may use either a surgical blade called a microkeratome or a femtosecond laser. The flap is folded back to reveal the cornea's midsection (stroma). The excimer laser sculpts the exposed corneal tissue. The corneal flap is put back in place. It reattaches within a few minutes without sutures. Eye drops are applied to aid healing. After surgery, your eyes may burn, itch, or feel irritated. This usually goes away within a day or so. It's important not to rub your eyes because this could move the flap. You will likely notice improved vision by the next day, although it can take as long as three to six months for vision to stabilize. Doctors have developed other surgeries similar to the standard LASIK procedure. These include the following. Wavefront-guided LASIK uses a highly detailed "map" of how light moves through the eye to guide the laser treatment. This shows even the subtlest distortions of focus. The goal is to reduce the chance of after-surgery problems such as glare, light "halos," blurry vision, and poor night vision. PRK (photorefractive keratectomy) corrects low to high nearsightedness, low to moderate farsightedness, and astigmatism. The eye surgeon removes the epithelium (surface cells on the cornea). The surgeon then uses the excimer laser to reshape the cornea. Healing occurs with help from a "bandage contact lens" applied at the end of the procedure. Initial healing occurs during the first week and may involve some discomfort. Full visual recovery may take weeks or months. For these reasons, LASIK surgery has generally replaced PRK, except for patients with corneas too thin for LASIK surgery or others with certain lifestyles or professions (such as professional athletes). LASEK (laser epithelial keratomileusis) is very similar to PRK. The difference is that the surgeon removes and then replaces the epithelium after completing the surgery. Like PRK, LASEK may be recommended for people with thin corneas. As with PRK, healing may involve some discomfort. Epi- LASIK uses a special instrument, the Epi-keratome, to create the corneal flap on the layer of cells covering the cornea (epithelium). Epi- LASIK is used primarily in patients who cannot have standard LASIK surgery. Several types of refractive surgery rely on implants to improve vision. These procedures include the following: Intrastromal corneal ring segment ( INTACS) implants Phakic intraocular lenses ( IOLs) Accommodative IOLs, multifocal IOLs, toric (astigmatism correcting) IOLs aka refractive lens exchange or clear lens extraction Each implant is described below. Intrastromal corneal ring segment ( INTACS) implants. Semicircular pieces of plastic are implanted in the cornea. These objects are called INTACS (intrastromal corneal ring segments). They change the cornea's shape and adjust the person's power to focus. INTACS are inserted through a small corneal incision. The incision is closed with two small sutures, or stitches, or with a special tissue glue. Stitches are typically removed two to four weeks later. If necessary, INTACS can be removed. The cornea returns to its original shape within a few weeks. These were introduced just prior to the emergence of LASIK as the dominant procedure to treat nearsightedness. LASIK and related procedures have replaced INTACS for refractive surgery. INTACS are now primarily used in the corneal degeneration called keratoconus. Phakic IOLs. These are used for people whose degree of nearsightedness or farsightedness is too high for safe use of the excimer laser. The procedure is similar to cataract surgery except that the natural lens is not removed. The eye surgeon positions a vision-correcting plastic lens in front of the patient's natural lens. Because the eye is actually entered, phakic IOL surgery considered more invasive than LASIK. This has to be balanced against the benefits to people with extreme eyeglass or contact lens prescriptions who are not eligible for a laser procedure. Accommodative IOLs, multifocal IOLs, toric (astigmatism correcting) and refractive lens exchange. These implants are used to treat nearsightedness, farsightedness, astigmatism, and presbyopia. Vision-correcting, surgically implanted artificial lenses replace the patient's natural lenses. No corneal reshaping is done. Radial keratotomy ( RK) was the first form of refractive surgery used in the U. S. It has been largely replaced by LASIK surgery. A variant of RK -- (limbal relaxing incision or arcuate keratotomy -- may be chosen to correct mild astigmatism. The eye surgeon uses a diamond scalpel to make cuts on the cornea. In RK, these cuts flatten and reshape the cornea. RK weakens the eye's structure over time, resulting in fluctuation in vision and long-term instability, the primary reasons it is seldom done now. Everyone considering LASIK or another refractive surgery should make the decision only after meeting with a refractive surgeon. General requirements include: Being age 18 or older Having healthy eyes Not needing a change in eyeglass or contact lens prescription over the past three years Having vision that refractive surgery can correct Most forms of refractive surgery may not be advisable for people who: Have a pre-existing eye disease Take certain prescription drugs known to affect vision or corneal healing Are pregnant or nursing Always ask your surgeon about the risks of surgery as well as the benefits. That way, you can make a more informed decision. The outcome will be more likely to meet your expectations. Typical costs for laser refractive surgery are between $1,500 and $3,500 per eye. Using wavefront technology or the "laser microkeratome" costs more. Procedures performed in practices where an experienced eye surgeon examines the patient before surgery, performs the surgery, and follows them afterwards are generally more expensive. Price also varies slightly by region. Be sure your surgeon makes clear what is and is not included in the price you are quoted. Ask, too, if you will have to pay more if you need follow-up visits or treatment for complications.