S, C, and A stand for spherical, cylindrical, and astigmatic axes in optometry, respectively. S stands for spherical lens power, which is myopia (indicated by “-” sign) or hyperopia (indicated by “+” sign), and C stands for cylindrical lens power, which is astigmatism (“-” sign for myopic astigmatism, “+” sign for hyperopic astigmatism). C stands for the cylindrical lens power, which is the degree of astigmatism (“-” sign for myopic astigmatism, “+” sign for hyperopic astigmatism).A stands for the axial position of astigmatism, which generally ranges from 0 to 180 degrees. For example, S-1.50, C-0.50, and A175 indicate that the patient has 150 degrees of myopia, 50 degrees of astigmatism, and 175 degrees of axial astigmatism. Patients with hyperopia or myopia can correct refractive errors and improve their vision by wearing spherical lenses, while patients with astigmatism can improve their vision by wearing column lenses. Patients with abnormal vision tests are advised to seek prompt medical attention to evaluate their condition and follow the doctor’s instructions for treatment.