An optometric examination result of minus 0.5 in cylindrical lenses indicates that the patient has 50 degrees of myopic astigmatism. In optometry, column lenses are used to correct astigmatism, so the column lens number represents the degree of astigmatism. A plus sign is for hyperopic astigmatism and a minus sign is for myopic astigmatism, so a cylindrical lens of minus 0.5 means that the patient has 50 degrees of myopic astigmatism. The cylindrical lenses usually have an axis of astigmatism after the lenses, which represents the amount of astigmatism at that axis. Astigmatism is due to the fact that light rays from different meridians do not converge on the retina when they enter the eye. Theoretically, a normal person’s astigmatism should be 0, but it is rare, so the normal range of astigmatism is 0 to 0.5. 50 degrees of astigmatism is relatively small, and has less impact on the patient’s visual function. It is recommended that patients with astigmatism consult a doctor in a timely manner to assess their condition and follow the doctor’s instructions for treatment.