Refractive complications of cataract surgery after radial keratotomy

As patients who have undergone radial keratotomy (several radial incisions into the cornea) grow older, more of them will undergo cataract surgery. It is not known how their corneas will respond to additional surgery. All patients have errors in refraction, a type of visual impairment, following keratotomy, usually immediately after surgery, but there is partial improvement after about three months. In some patients improvement may not occur for up to five years; corneal healing from keratotomy may require several years. Four cases describe refractive complications following cataract surgery in patients who had undergone radial keratotomy several years earlier. These patients had cataract surgery with insertion of a posterior chamber intraocular lens. All patients had some initial hyperopia (farsightedness) caused by flattening of the cornea. This condition partially regressed and an average of 0.42 diopter of flattening persisted (remained mildly farsighted). The amount of flattening of the cornea decreased as the interval between keratotomy and cataract surgery increased. After keratotomy the topography of the corneal curvature is changed, with the center being flatter than the edges. It was observed that measurements of the curvature of the cornea, necessary for selection of the proper intraocular lens (to be inserted during cataract surgery), were less accurate when measured with a keratometer. A new system of measurement is recommended.