Astigmatism might require corrective lenses or glasses. At what level of astigmatism would I need help?

When blurred. Astigmatism is very common -- almost everyone has a little bit. It simply means that the cornea is not perfectly round, but rather has one steeper and one flatter curvature (like the side of a football rather than a basketball). People with more than 0.75diopters of astigmatism usually notice that images are blurred without glasses or contacts.