Final answer:
Astigmatism creates a visual problem where the eye's focus is uneven, leading to blurry or distorted images, typically caused by irregularities in the cornea or lens. It can be detected with a chart and corrected with cylindrical lenses.
Step-by-step explanation:
The visual problem created by astigmatism is an unevenness or asymmetry in the focus of the eye, leading to blurry or distorted vision. This condition usually occurs due to irregularities in the shape of the cornea, the lens, or unevenness in the retina. Astigmatism causes rays of light entering through different parts of the eye to focus at varying points, resulting in images that can appear elongated or less distinct along certain axes. It can be detected by using a special chart, where if lines along some axes appear darker or clearer than others when viewed separately by each eye, the presence of astigmatism is indicated. Additionally, astigmatism can be partially corrected with spectacles that contain a cylindrical correction to counteract the eye's irregularity, contrasting the spherical corrections used for short- or farsightedness which are uniform along all axes.