Astigmatism is one of the types of focus problems, the others are long and myopic. In astigmatism, light is focused differently depending on which direction light rays shine as they pass through a lens.
Like other focusing problems, astigmatism affects vision in proportion to its degree. The greater the astigmatism, the more blurred the resulting vision.
One group of people with high astigmatism would need to wear glasses all the time, which would be children under about 9 or 10 years old with astigmatism greater than about 1.50D. If these children do not wear their glasses, the constantly blurred vision could cause lazy eye (amblyopia).
For older people, glasses are purely a visual aid, that is, they help provide clear vision, but do not otherwise affect the health of the eye whether worn or not. So it’s up to them whether they wear the glasses all the time or not, without glasses the vision is blurry, with the glasses the vision is clear, and that’s it.
Regular and stable astigmatism is not really a disease, it’s just who you are and reflects the shape of your eyeball. But if you don’t want to wear glasses or contact lenses, then the only other way to get rid of it would be through refractive surgery, ie LASIK, PRK or ICL.