Radial keratotomy (RK) is surgical procedure to reduce myopia (nearsightedness) by changing the curvature of the cornea. RK was invented in the 1930s and perfected in the late 1970s.

People with myopia have difficulty with distance vision because the cornea has too much power and focuses light rays in front of the retina. RK weakens the midperiphery of the cornea, producing a central flattening and a reduction in its power. This allows the light rays to focus more precisely on the retina without the need for eyeglasses or contact lenses.

RK takes approximately 15 minutes and can be performed with the patient awake. Eyedrops anesthetize the cornea, eliminating pain during the procedure. Using a microscope, microsurgical instruments, and a diamond blade, the surgeon makes several deep incisions (keratotomies) in the cornea in a radial or spoke-like pattern. Following surgery, patients are moderately uncomfortable and often require oral pain medication. Antibiotic and steroid eyedrops are necessary for approximately one week. Clear vision can be present the day following surgery.

Postoperative complications include glare, halos, undercorrection, overcorrection, and astigmatism that may not be able to be corrected with glasses. The major disadvantage of RK compared to laser procedures is that it permanently weakens the cornea. Additionally, some patients complain of progressive hyperopia (farsightedness) as well as a fluctuation in vision throughout the day. Radial keratotomy is currently being used to correct low levels of myopia.

(c) 2007 The American Academy of Ophthalmology