Astigmatism is measured in units of diopters. A perfect eye will have 0 diopters, but most people have between 0.5 to 0.75 diopters of astigmatism.7

 Patients will only need glasses or contact lenses if the measurement is 1.5 diopters or more.

The last two numbers in your prescription refer to astigmatism:8

• Cylinder measures what degree of astigmatism you have, or how flat or irregular the shape of your cornea is.
• Axis is measured in degrees and ranges from 0 to 180.