Astigmatism cannot cause blindness although astigmatism makes it harder for people with astigmatism to see properly.
You will not go blind when you have astigmatism so there's no need to worry about that and if you went blind or are going blind when you have astigmatism then the blindness is caused by something else.
Astigmatism is not a health condition or eye disease but instead it's just a problem with how your eye focuses light which is usually caused by a defect in the eyes lens, resulting in distorted images.
Astigmatism cause cause blurred vision, eye strain, and headaches and make it very difficult at times for people to see properly but astigmatism cannot cause or lead to blindness.