Visual acuity of 5.0 belongs to normal vision, degree generally refers to the refractive error, visual acuity and refractive error there is no conversion between the standard, the two are the results of different ophthalmologic examination. 1. Visual acuity: this index mainly reflects the function of the macular area, generally divided into distance vision and near vision, mainly through the results of vision checklist examination, the clinical standard of normal vision is ≧5.0. 2. Refraction: This index mainly reflects whether the eyes are able to image in the retina, the object imaging on top of the retina is called orthopia, no imaging on the retina is called refractive error, common refractive errors include myopia, hyperopia and astigmatism, which generally need optometry diagnosis. Patients can go to specialized eye hospitals for vision examination and refraction examination.