title: Bilateral comparison of photorefractive keratectomy for myopia using two excimer lasers.
abstract: OBJECTIVE
  The aim of this study was to compare the results of excimer laser photorefractive keratectomy (PRK) in patients who underwent PRK using the Summit Apex (Omnimed) excimer laser in one eye and the Nidek EC-5000 excimer laser in the other.
  
  
  METHODS
  All consecutive patients who underwent PRK with the Summit Apex laser (Omnimed) in one eye and the Nidek laser (EC-5000) in the second and had at least 12 months of follow-up were included in this retrospective study (n=30). Uncorrected and spectacle-corrected visual acuity, final spherical equivalent refraction, and grade of subepithelial haze were compared. The average preoperative spherical equivalent refraction of eyes treated with the Summit laser was -6.00 D (range, -2.50 to -8.75 D), and for Nidek-treated eyes it was -5.57 D (range, -2.50 to -8.80 D).
  
  
  RESULTS
  Forty-seven percent of Summit-treated eyes and 53% of Nidek-treated eyes had uncorrected visual acuity of 6/6 or better; 61% of Summit-treated eyes and 63% of Nidek-treated eyes had uncorrected visual acuity of 6/7.5 or better; 95% of Summit-treated eyes and 95% of Nidek-treated eyes had uncorrected visual acuity of 6/12 or better (difference not statistically significant). Seventy-three percent of eyes treated with the Summit laser and 80% of eyes treated with the Nidek laser had a postoperative refraction within +/-0.50 D of emmetropia; 97% of Summit-treated eyes and 87% of Nidek-treated eyes had a postoperative spherical equivalent refraction within +/-1.00 D of emmetropia; the difference between the two lasers was not statistically significant. However, the percent of eyes with persistent hyperopia was smaller in the Nidek group after 3 months (P=.0062) and after 6 months (P=.07) than in the Summit group. Videokeratography was not done.
  
  
  CONCLUSIONS
  Both lasers were effective with relatively low side effects. No significant difference was found between the two lasers in postoperative uncorrected visual acuity or refractive outcome. Eyes operated with the Nidek laser had less persistent hyperopia and stabilized earlier.
authors.affiliation: Department of Ophthalmology, Tel Aviv Sourasky Medical Center, Israel.
authors.forename: I
authors.initials: I
authors.lastname: Lipshitz
authors.forename: L
authors.initials: L
authors.lastname: Fisher
authors.forename: M
authors.initials: M
authors.lastname: Lazar
authors.forename: A
authors.initials: A
authors.lastname: Loewenstein
mesh_terms: D000328:Adult; D003315:Cornea / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053685:Laser Therapy; D007834:Lasers; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000379:methods*; D012029:Refraction, Ocular; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity