Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study 4 years after surgery for myopia. Perk Study Group

JAMA. 1990 Feb 23;263(8):1083-91.


The Prospective Evaluation of Radial Keratotomy Study is a nine-center clinical trial of a surgical technique to reduce simple myopia by making incisions in the cornea. There were 435 patients (one eye per patient is reported) enrolled in the study with a 91% follow-up rate at 4 years after surgery. After surgery, uncorrected visual acuity was 20/40 or better in 76% of eyes. Fifty-five percent of the eyes had a refractive error within +/- 1.00 diopter; 28% were undercorrected, and 17% were overcorrected by more than 1.00 D. The width of the prediction 90% interval for the refractive change was 4.42 D, indicating a lack of predictability. The refractive error was not stable in some eyes; between 6 months and 4 years after surgery, 23% of eyes had a continued effect of the surgery of more than 1.00 D. For 323 patients with both eyes operated on, 64% stated they wore no optical correction. There were few serious complications. Eleven eyes (3%) lost two or three lines of best corrected visual acuity. Two eyes developed delayed bacterial keratitis without significant loss in best corrected visual acuity.

Publication types

  • Clinical Trial
  • Multicenter Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Astigmatism
  • Clinical Trials as Topic
  • Evaluation Studies as Topic
  • Humans
  • Keratotomy, Radial* / statistics & numerical data
  • Middle Aged
  • Multicenter Studies as Topic
  • Myopia / physiopathology
  • Myopia / surgery*
  • Outcome and Process Assessment, Health Care / statistics & numerical data*
  • Postoperative Complications
  • Prospective Studies
  • Refraction, Ocular
  • Visual Acuity