Symmetry of outcome after photorefractive keratectomy for myopia

The aim of this study was to find out whether the outcome of excimer laser photorefractive keratectomy (PRK) in the second eye can be predicted from the results of the first, and to determine whether we should modify our therapeutic approach to the second eye according to the results of the first. Bilateral PRK was performed in 73 patients using the Summit Technology excimer laser. All patients included in this study had a follow-up of at least 12 months in both eyes. The change of refraction and the haze of the two eyes were compared. Sixty percent of patients had a difference in refraction between the two eyes smaller than 0.50 diopters (D), and 75% had a difference smaller than 1.00 D. The degree of symmetry in response to treatment was greater in patients with a preoperative spherical equivalent refraction of less than -6.00 D. Most patients had a similar degree of haze in both eyes. The results of our study demonstrate that a considerable degree of symmetry in the outcome of surgery exists between the two eyes of the same patient undergoing PRK, especially in low to moderate myopia.