Radial Keratotomy (RK)
RK was the first viable surgical alternative for the correction of refractive problems. RK involves the placement of four to eight radial incisions in the outer perimeter of the cornea. As these incisions heal, the cornea is flattened to correct nearsightedness. More people have had this procedure done than any other vision correction surgery; however, it has been largely replaced by LASIK, PRK and other newer techniques.
Photorefractive Keratectomy (PRK)
PRK gained popularity rapidly as a replacement for Radial Keratotomy (RK). PRK was the first procedure to treat nearsightedness with the excimer laser and is still the procedure of choice for some patients. The PRK procedure corrects the shape of the cornea with the precision of the excimer "cool" laser by altering layers of the corneal tissue as thin as three ten-thousandths of a millimeter.
Intacs Corneal Ring Segments
Intacs corneal ring segments are a non-laser treatment for the correction of mild to moderate levels of nearsightedness. These clear, plastic arcs are implanted in the stromal layer of the cornea outside of the central vision zone. The result is a reshaping of the cornea and subsequent correction of some refractive disorders.
This investigational procedure is for the treatment of some cases of farsightedness and/or astigmatism. The procedure uses a special laser, called a Holmium YAG laser, to warm and shrink the collagen - protein structures within the corneal tissue. As the collagen shrinks, the curvature of the cornea is changed.
Intraocular Lens Implant
Also known as lensectomy, this procedure is sometimes used to reduce severe cases of either nearsightedness or farsightedness. As with cataract surgery, the natural crystalline lens of the eye is removed and a plastic intraocular prescription lens is inserted. Although this may be an ideal procedure for some patients, the artificial lens has a set focus. Therefore, reading glasses or contact lenses are usually still needed for close-up vision.
This procedure involves implanting a tiny plastic prescription lens within the corneal tissue. Several types of lenses are available to correct various vision problems including presbyopia. The presbyopia lens, which creates an effect like a bifocal, is still investigational, but early results appear promising for reducing dependence on bifocal eyeglasses.