Bilateral comparison of photorefractive keratectomy for myopia using two excimer lasers

PURPOSE: The aim of this study was to compare the results of excimer laser photorefractive keratectomy (PRK) in patients who underwent PRK using the S ummit 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 la ser (Omnimed) in one eye and the Nidek laser (EC-5000) in the second and ha d 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 t he Summit laser was -6.00 D (range, -2.50 to -8.75 D), and for Nidek treate d 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-treate d eyes had uncorrected visual acuity of 6/6 or better; 61% of Summit-treate d 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 un corrected visual acuity of 6/12 or better (difference not statistically sig nificant). Seventy-three percent of eyes treated with the Summit laser and 80% of eyes treated with the Nidek laser had a postoperative refraction wit hin +/-0.50 D of emmetropia; 97% of Summit-treated eyes and 87% of Nidek-tr eated eyes had a postoperative spherical equivalent refraction within +/-1. 00 D of emmetropia; the difference between the two lasers was not statistic ally significant, However, the percent of eyes with persistent hyperopia wa s 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. CONCLUSION: Both lasers were effective with relatively low side effects. No significant difference was found between the two lasers in postoperative u ncorrected visual acuity or refractive outcome. Eyes operated with the Nide k laser had less persistent hyperopia and stabilized earlier.