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Abstract:
The operation of radial keratotomy is undergoing evolution and development. A few hundred thousand radial keratotomy procedures have been performed during the past decade by approximately 10% of the ophthalmologists in the United States. Clinical and laboratory data have now defined a relative level of safety and effectiveness for the procedure. Published data indicate that radial keratotomy usually achieves partial improvement in uncorrected visual acuity in patients with non-progressive low and moderate amounts of myopia. Undercorrection occurs commonly, and the amount of correction cannot be predicted accurately for an individual patient. Overcorrection occurs less often using four incisions. The unpredictability of the refractive outcome stems from several factors, including: 1) the biologic variability from one individual to another, 2) variation in surgical techniques among surgeons, 3) difficulty in making all incisions uniformly, and 4) inability to measure and control the biomechanical properties of the cornea. This is probably why there is not unanimity among radial keratotomy surgeons regarding the most effective surgical technique. Improvements in the surgery are occurring, including the use of staged, titrated techniques, and some series of radial keratotomy cases have reported better uniformity and predictability of outcome. The potential of this procedure to render good visual acuity without glasses or contact lenses must be weighed against its known risks. Refractive side effects include anisometropia (imbalanced vision between the two eyes), increased astigmatism, and symptomatic presbyopia (loss of near focus in middle life). Other common, usually less severe side effects include prolonged unstable vision and mild glare. Uncommon, but potentially binding, complications include ocular infection and traumatic rupture of the cornea at the keratotomy scars. The goal of radial keratotomy is to correct the refractive error of myopia. It also may serve to improve cosmetic appearance if the patient does not require glasses after surgery. It is elective surgery because other alternatives are available for the management of myopia, including conventional glasses and contact lenses. In addition, other refractive keratoplasty procedures are available, including excimer laser photorefractive keratectomy, keratomileusis and epikeratoplasty. Selection of the best alternative for the management of myopia in an individual patient should be based on the patient's personal needs and on the ophthalmologist's and patient's assessment of the risks and benefits of the available modes of correction.