RADIAL KERATOTOMY

surgical procedure to correct myopia (nearsightedness) by reducing the radius of curvature of the cornea and astigmatism (asymmetrical curvature of the cornea). A series of 4 to 8 equally spaced deep cuts are made in the peripheral cornea, leaving the central cornea above the pupil clear. Intraocular pressure then pushes the weakened central cornea outward, flattening it and modifying its refractive power. Wound contraction during healing also affects corneal curvature by exerting radial tension on the uncut area. Radial keratotomy improves visual acuity to a modest extent, enabling some people with low-level myopia to see well without the aid of spectacles or contact lenses. The procedure has been somewhat controversial, however, because the degree of improvement is unpredictable, depending in part on individual healing rate. Some people who have undergone surgery still require corrective lenses. The procedure is irreversible and may leave extensive scars on the cornea, causing glare in bright light and possibly interfering with the wearing of contact lenses (in cases of continued myopia). Because repeated operations to correct residual defects may be effective in some cases and do not seem to increase the complications of the initial procedure, some surgeons have suggested that the operation be performed in stages until optimal visual correction can be achieved, but this view is not widely accepted. The improvement in vision that may occur with additional operations must be weighed against increased corneal scarring.