How to read an eyeglass prescription for myopia degree

In a prescription for eyeglasses, there are many symbols and figures. Here, "R" stands for the right eye and "L" for the left eye. S, C, and A represent spherical lens (SPH), cylindrical lens (CYL), and axis of astigmatism, respectively. To determine the degree of myopia, one should primarily focus on the values of the spherical and cylindrical lenses. The specific analysis is as follows:

Generally, the value of the spherical lens indicates the patient's spherical refractive power. To obtain the actual diopter, multiply the number shown on the prescription by 100. For example, the S value on an eyeglass prescription is often something like 3.x, 4.x, or x.x; only when multiplied by 100 can the patient’s exact diopter be determined. If the spherical lens value is positive, it indicates hyperopia (farsightedness); if negative, it indicates myopia (nearsightedness). For instance, a spherical value of -2.00 means 200 degrees of myopia. However, individuals with myopia often also have some degree of astigmatism, which requires checking the cylindrical lens value. For example, if the cylindrical lens value is -0.75, this indicates 75 degrees of myopic astigmatism. After the astigmatism value, an axis number is always indicated. For example, if the value under A is 180, this means the axis of astigmatism is 180.

Please note that everyone's situation is different; therefore, to accurately determine the degree of myopia, it is necessary to undergo professional examination at a qualified medical facility, so that appropriate corrective lenses can be prescribed.