一般的屈光不正,用镜片可以矫正;但有时候,特别是高度散光,用接触镜也不能满意地增进视力。角膜的疾病、外伤或手术可以引起屈光改变,有时可达30D之多。过去几十年有许多人研究用手术方法使角膜曲度改变以纠正屈光不 General refractive error, with the lens can be corrected; but sometimes, especially high astigmatism, with contact lenses can not satisfactorily enhance vision. Corneal disease, trauma or surgery can cause refractive changes, sometimes up to 30D as much. Many people over the past few decades have studied surgical procedures for changing corneal curvature to correct refractive errors