Results of the Prospective Evaluation of Radial Keratotomy (PERK) Study One Year After Surgery

George O. Waring, Michael J. Lynn, Henry Gelender, Peter R. Laibson, Richard L. Lindstrom, William D. Myers, Stephen A. Obstbaum, J. James Rowsey, Marguerite B. McDonald, David J. Schanzlin, Robert D. Sperduto, Linda B. Bourque, George O. Waring, Ceretha S. Cartwright, Eugene B. Steinberg, H. Dwight Cavanagh, William H. Coles, Louis A. Wilson, E. C. Hall, Steven D. MoffittPortia Griffin, Vicki Rice, Sidney Mandelbaum, Richard K. Forster, William Culbertson, Mary Anne Edwards, Teresa Obeso, Marguerite McDonald, Aran Safir, Herbert E. Kaufman, Rise Ochsner, Joseph A. Baldone, John Lindberg, Rudy Franklin, Deborah Poloson, Mike Ostrick, Donald J. Doughman, J. Daniel Nelson, J. Douglas Cameron, Pat Williams, Penny Asbell, Steven M. Podos, Michael J. Newton, George Pardos, Norma Justin, Hal D. Balyeat, James C. Hays, Wayne F. March, Jack Whiteside, Becky Hewett, Douglas Corley, Beth Kuns, Ronald E. Smith, James J. Salz, Douglas L. Steel, Richard A. Villasenor, Jenny Garbus, Jan Reinig, Robert C. Arends, John W. Cowden, William T. Sallee, Robert L. Stephenson, Paul Fecko, Henry J. Spiro, Vicki Roszka-Duggan, Juan J. Arentsen, Michael A. Naidoff, Elisabeth Cohen, Nubia Cantillo, Roy Monlux, Michael Isaac, Beverly Cosand, Shari Swift, Darrl Clark, Vicki Shadix, Jay H. Krachmer, Robert J. Hardy, James P. McCulley, Walter J. Stark, Richard A. Thoft, James V. Aquavella, Jules L. Baum, Joel Sugar, James Ware, Michale J. Lynn, Ronald G. Geller, Ralph J. Helmsen

    Research output: Contribution to journalArticlepeer-review

    173 Scopus citations


    The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between −2.00 and −8.00 diopters. The surgical technique consisted of eight incisions using a diamond micrometer knife with blade length determined by intraoperative ultrasonic pachymetry and the diameter of central clear zone determined by preoperative refraction. At one year after surgery, myopia was reduced in all eyes; 60% were within ±1.00 diopter of emmetropia; 30% were undercorrected and 10% were overcorrected by more than 1.00 diopter (range of refraction, −4.25 to +3.38 D). Uncorrected visual acuity was 20/40 or better in 78% of eyes. The operation was most effective in eyes with a refraction between −2.00 and −4.25 diopters. Thirteen percent of patients lost one or two Snellen lines of best corrected visual acuity. However, all but three eyes could be corrected to 20/20. Ten percent of patients increased astigmatism more than 1.00 diopter. Disabling glare was not detected with a clinical glare tester, but three patients reduced their driving at night because of glare. Between six months and one year, the refraction changed by >0.50 diopters in 19% of eyes.

    Original languageEnglish
    Pages (from-to)177-198
    Number of pages22
    Issue number2
    StatePublished - 1985


    • astigmatism
    • clinical trial
    • cornea
    • glare
    • myopia
    • radial keratotomy
    • refractive keratoplasty


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