Astigmatism is a very common optical condition that is often misunderstood. Like farsightedness and nearsightedness, it too blurs vision but only in one direction.
The first image demonstrates normal clarity.
The second image demonstrates blur with astigmatism. Notice that certain lines appear clearer than others.
Because astigmatism blurs in one direction, it can do so along any direction around the clock (e.g. 3-9:00, 6-12:00, 1-7:00). In this photo, the vertical lines appear sharper than the horizontal. It's very subtle just as it is with vision.
People with low corrections with astigmatism rarely like wearing their glasses even when they see clearer with them. Although clearer, astigmatic glasses distort one's perception of space and often cause dizziness. People often prefer seeing slightly blurred without the spatial distortion. If one were to continually wear the glasses, the brain would eventually adapt to the prescription eliminating the spatial distortion. Sometimes making smaller astigmatic changes allows for easier adjustment to the new prescription.
Another way to eliminate the spatial distortion associated with astigmatic glasses is to wear contact lenses. Contact lenses, both rigid and soft can compensate for astigmatism without creating distortion.