Today's refractive surgery options for vision correction range from corneal reshaping with lasers to surgical insertion of artificial lenses. Following are some of the alternative refractive surgery procedures to LASIK and PRK.
Before surgery, the excimer laser is programmed with each patient's wavefront data to prepare it to perform a very precise "sculpting" of each unique cornea. In conventional LASIK, this programming is based on the patient's vision correction prescription (the same as used for the patient's glasses or contacts.)
In wavefront-guided LASIK, computer imaging technology creates a very detailed three-dimensional "map" of the patient's cornea that looks a bit like a miniature mountain range. This "map" is used to program the excimer laser for surgery. Wavefront technology can measure very subtle abnormalities in the surface of the cornea, enabling wavefront-guided LASIK to achieve vision correction beyond what is possible with glasses or conventional LASIK.
Also, wavefront LASIK has been shown in several studies to reduce side effects, such as problems with night vision and contrast sensitivity (the ability to clearly see objects against a background, such as black letters on a white page), and also to increase the percentage of patients who achieve 20/20 vision. Wavefront technology may also be used in PRK procedures, for similar reasons and with similar results.
A microsurgical instrument called a trephine is used to create a flap of epithelial corneal tissue, and an alcohol solution is used to loosen the epithelial cells. Once the epithelial flap is created and moved aside, the procedure is the same as PRK. After corneal sculpting, the epithelial flap is repositioned and smoothed with a small spatula, then secured with a "bandage" soft contact lens to promote epithelial healing, which takes about four days.
A special microkeratome, the Epi-keratome, is used to precisely separate a very thin sheet of epithelial tissue from the cornea. This thin sheet is lifted to the side and the cornea is treated as with PRK. Then the thin sheet may be moved back into place to re-adhere to the cornea or removed. A "bandage" soft contact lens is applied and used for about four days to help the epithelial layer heal.
Conductive Keratoplasty (CK)
CK is a noninvasive, thermal refractive surgery procedure used to correct mild to moderate farsightedness (hyperopia) in people over age 40. With CK, your ophthalmologist uses a tiny probe that releases controlled amounts of radio frequency (RF) energy, instead of a laser, to apply heat to the peripheral portion of the cornea. The heat then causes the peripheral cornea to shrink and tighten like a belt. This increases the curvature (steepness) of the central cornea, improving the optical power of the central cornea. This refocuses light rays on the retina and enhances vision.
CK can be used to achieve "monovision" (blended vision). With monovision, CK can be used to improve close-up vision in a presbyopic eye with good vision but poor near focus. To maintain good distance vision, usually only one eye is set to near focus (the non-dominant eye), while the other is left or set at good distance vision. CK does not offer permanent correction; for some people, farsightedness may return over time.
Phakic Intraocular Lenses (IOLs)
Phakic IOLs are designed for people with high degrees of refractive errors that cannot be safely corrected with corneal-based refractive surgery. The phakic IOL, sometimes referred to as an implantable contact lens, or ICL, is surgically implanted inside the eye in front of the eye's natural lens. The eye's natural lens is not removed, so patients can retain their pre-existing ability to focus.
During the phakic IOL procedure, your ophthalmologist places the phakic IOL either in front of or behind the iris of the eye. Once the IOL is properly positioned inside the eye, it provides the necessary correction to redirect light rays precisely onto the retina.
Refractive Lens Exchange (Clear Lens Extraction)
With refractive lens exchange (RLE) — also called Clear Lens Extraction or CLE — an artificial lens is used to replace your eye's natural lens in order to improve vision. The procedure is performed much like cataract surgery.
As is an option in cataract surgery, RLE may employ multifocal or accommodative intraocular lenses (IOLs). These lenses allow the ability to focus at all distances.
Some people who have early stage cataracts may choose to have RLE instead of waiting for their cataracts to progress to the point where they should be removed. This is because the lens implants generally provide them with better uncorrected vision at that point, particularly if they currently need vision correction.
RLE may also be an option for people with severe hyperopia (farsightedness), for whom LASIK is not recommended.
RLE is not FDA-approved, however, ophthalmologists legally may choose to perform this procedure in what is called an "off-label" use.