eal incisions. A criticism of RK is its lack of predictability. As with other refractive conventional surgeries, problems such as overcorrection or undercorrection of refractive errors are found. Factors affecting predictability have been studied, it has been concluded that the surgeon's selection of the area of the optical clear zone, is the most important factor that determines refractive change by RK. For RK, deep radial incisions made with a diamond scalpel, weaken the cornea periphery, causing it to bulge outward and the central cornea to be flatter. This surgery is now rarely performed (Anonymous, 1999, p. 123; Sanders, Deitz, & Gallagher, 1985, p. 1237; Rowsey, & Rubin, 1988, p. 414).
Intracorneal rings and phakic intraocular lenses have also been used to treat myopia. Intracorneal rings for low to moderate myopia is a difficult surgery with a high risk of astigmatism. Although the use of these lenses for those with high myopia was initially exciting, all intraocular surgery can result in devastating infection; rates are 0.3% (Shah & Dua, 2000, p. 7232). FDA backed KeraVision's Intacs, or intrastromal corneal ring, for the reshaping of a cornea's curvature. An advantage to this procedure, is that it can be reversed if patients experience dissatisfaction. A disadvantage is that people tend to take them out due to disappointment with vision correction or side-effects such as night vision problems, glare, and haloing. Intracorneal rings can result in infection, astigmatism, and anterior chamber perforation. Phakic intraocular lenses can result in damage to the corneal endothelium, retinal detachment, cataract formation, and glaucoma (Anonymous, 1999, p. 123; Ault, 1999, p. 300).
Laser eye surgery for refractive changes surfaced in the 1980s. Excimer laser corneal surgery is used in refractive surgery to correct myopia and astigmatism. Around 60 million people in the United States are reported to be nearsighted,...