What does axis mean on an eye exam?

In an eye exam, "axis" refers to the orientation of astigmatism in the eye, measured in degrees from 1 to 180. It indicates the direction of the steepest and flattest meridians of the cornea or lens, helping to determine how corrective lenses should be shaped to compensate for the irregular curvature. The axis value is crucial for ensuring that glasses or contact lenses effectively correct vision by aligning properly with the eye's astigmatism.