Results of Phase III Excimer Laser Photorefractive Keratectomy for Myopia Journal Articles uri icon

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  • OBJECTIVE: The purpose of the study is to determine safety and efficacy outcomes of excimer laser photorefractive keratectomy (PRK) for the treatment of mild-to-moderate myopia. DESIGN: A prospective, multicenter, phase III clinical trial. PARTICIPANTS: A total of 701 eyes of 701 patients were entered in the study; 612 eyes were examined at 2 years after surgery. INTERVENTION: Intervention was photorefractive keratectomy using the Summit ExciMed UV200LA excimer laser (Summit Technology, Inc., Waltham, MA). The treatment zone diameter used was 4.5 mm in 251 eyes (35.8%) and 5 mm in 450 eyes (64.2%). Attempted corrections ranged from 1.50 to 6.00 diopters (D). MAIN OUTCOME MEASURES: Predictability and stability of refraction, uncorrected and spectacle-corrected visual acuity, refractive and keratometric astigmatism, corneal haze, contrast sensitivity, subjective reported problems of glare and halo, and patient satisfaction were the parameters measured. RESULTS: At 2 years, 407 (66.5%) eyes achieved 20/20 or better uncorrected visual acuity and 564 (92.5%) eyes achieved 20/40 or better visual acuity. Three hundred thirty-six (54.9%) eyes were within 0.5 D and 476 (77.8%) eyes were within 1.0 D of attempted correction. Stability of refraction improved with time; 86.8% of eyes were stable within 1.0 D from 6 to 12 months, 94% were stable from 12 to 18 months, and 96.3% were stable from 18 to 24 months. There was no evidence of progressive or late myopic or hyperopic refractive shifts. One hundred fourteen (18.6%) eyes gained 2 or more lines of spectacle-corrected visual acuity, whereas 42 (6.9%) eyes lost 2 or more lines; however, of the latter, 32 (76.2%) had spectacle-corrected visual acuity of 20/25 or better and 39 (92.9%) eyes had 20/40 or better. Four hundred forty-two (72.2%) corneas were clear, 138 (22.5%) showed trace haze, 20 (3.3%) mild haze, 9 (1.5%) moderate haze, and 3 (0.5%) marked haze. On patient questionnaires, 87 (29.7%) patients reported worsening of glare from preoperative baseline; 133 (50.1%) reported worsening of halo symptoms from baseline. CONCLUSIONS: Photorefractive keratectomy appears effective for myopic corrections of -1.50 to -6.00 D. Uncorrected visual acuity is maximized in most eyes by 3 months, although some patients require between 6 months and 1 year to attain their best postoperative uncorrected visual acuity and some may require from 1 to 2 years for stabilization of refraction. Refraction stabilizes progressively without evidence of late myopic or hyperopic refractive shifts. Optical sequelae of glare and halo occur in some patients treated with a 4.5- or 5-mm treatment zone.


  • Wright, James
  • Hersh, Peter S
  • Stulting, R Doyle
  • Steinert, Roger F
  • Waring, George O
  • Thompson, Keith P
  • O'Connell, Maureen
  • Doney, Kimberley
  • Schein, Oliver D
  • Michelson, Marc
  • Owen, John
  • Gordon, Michael
  • Wright, John R
  • Waring, George O
  • Stulting, R Doyle
  • Thompson, Keith P
  • Brint, Stephen
  • Steinert, Roger
  • Mead, Mariana
  • Raizman, Michael
  • Wu, Helen
  • Durrie, Daniel
  • Cavanaugh, Timothy
  • Hunkeler, John
  • Pepose, Jay
  • Galusha, J Harley
  • Gold, Daniel H
  • Milstein, Bernard A

publication date

  • October 1997

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