Final answer:
Astigmatism results from an irregularity in either the cornea or lens of the eye.
Astigmatism occurs due to irregularities in the cornea's shape or the lens of the eye, leading to uneven focus and can be detected with a special chart.
Step-by-step explanation:
Astigmatism results from an irregularity in either the cornea or lens of the eye. This condition leads to unevenness or asymmetry in the focus, causing rays of light to focus at different points, which may result in a less distinct vision or sharper images along certain axes. Such irregularities can often be corrected with spectacles that have a cylindrical correction to counter the eye's specific irregularity. Unlike spherical corrections for short- or farsightedness, which are uniform along all axes, these corrections are tailored to the individual's astigmatism. A common method for detecting astigmatism is using a chart where, if lines along some axes appear darker or clearer than others when looking at a central cross, it suggests the presence of astigmatism.