摘要目的　探讨准分子激光角膜切削术(photorefractive keratectomy, PRK)后肌性视疲劳与切削偏心的关系。方法　对8例16眼近视性屈光不正行PRK后随防6-14个月，视力均在0.8以上且主观接受棱镜矫正的肌性视疲劳者，根据术后与术前的角膜地形图及其相减图的数据，按Holladay法计算角膜实矫屈光度D，检测偏离瞳孔中心的切削偏心量h(以mm为单位)及方向。用公式δ(棱镜度)≈Dh计算切削偏心所致棱镜效应值并与主观接受矫正的棱镜相比较。结果　主观接受与按公式计算的棱镜度相近，两者差值平均为0.10±0.25，主观接受的棱镜基底朝向均与偏心方向一致。结论　切削偏心为PRK后肌性视疲劳的主要原因，偏心所致棱镜效应可用≈Dh估算；应重视PRK后肌性视疲劳的诊断、治疗和预防。

abstractsObjective　To investigate the relationship between muscular asthenopia post photorefractive keratectomy (PRK) and eccentric ablation.Methods　16 eyes of 8 myopia cases whose muscular asthenopia was corrected by subjectively accepted triangular prism after PRK with vision more than 0.8 were followed up for 6-14 months. On the basis of data provided by the pre-PRK, post-PRK and their difference corneal topography, we calculated the real corrected corneal diopter (D) with the Holladay formula and measured the ablating eccentricity (h) and its direction. According to the formula δ≈Dh, the prism effective value (δ) caused by the eccentric ablation was computed and compared with objectively accepted triangular prism.Results　The subjectively accepted prism was similar to values calculated from the formula. Their mean difference is 0.10±0.25. The direction of the subjectively accepted prism was in the direction of ablation deviation.Conclusions　Eccentric ablation was the chief cause of post-PRK muscular visual asthenopia. The triangular prism effective value from eccentric ablation may be estimated by the formula δ≈Dh. We must pay attention to the diagnosis, treatment and prevention of post-PRK muscular asthenopia.