Comparison of asymmetric and symmetric offset ablation in myopic astigmatism patients

To compare differences in clinical outcomes of symmetric offset (SO) and asymmetric offset (AO) centration strategies in photorefractive keratectomy (PRK) in patients with myopia or myopic astigmatism.旨在比较在近视或近视散光患者中，采用对称偏移（SO）策略与不对称偏移（AO）策略进行光折射性角膜磨削术（PRK）的术后临床效果差异。