Bilateral refractive error of the eye means that there is some abnormality in the refraction of both eyes. This refractive error is a generic term for many refractive disorders, such as farsightedness, myopia, and astigmatism, all of which can be called refractive errors. Myopia is generally defined as a degree of 50 degrees or more, and is called myopia. Farsightedness is also defined as a degree of farsightedness of 50 degrees or more, called hyperopia, and astigmatism is called astigmatism as long as there is a degree. So once there is such a refractive type of problem, then in the clinical are collectively called refractive error. Therefore, if the refractive error is bilateral, it means that both eyes may have problems such as farsightedness, myopia or astigmatism. If these problems affect vision, then glasses may be required. If the effect on vision is not significant, then it is okay to follow up and observe.