Final answer:
Astigmatism, which is caused by irregularities in the cornea, lens, or retina, results in uneven vision. It is corrected using cylindrical correction lenses or more accurately through LASIK surgery, wherein a laser reshapes the cornea allowing for sharp distant vision in over 90% of patients.
Step-by-step explanation:
To control radial astigmatism, correction lenses such as spectacles with a cylindrical correction are used. Astigmatism is caused by irregularities in the shape of the cornea, but it can also be due to irregularities in the lens or retina. The condition leads to unevenness or asymmetry in the focus of the eye, causing images to be focused at different locations. This results in vision that is less sharp or images that appear elongated along certain axes. A chart test, where you look at a central cross and note whether lines along some axes appear darker or clearer, can help detect astigmatism. For more precise correction, LASIK surgery can be employed. This surgical procedure uses a laser to reshape the cornea by removing microscopic layers of tissue with great precision. A computer controls the bursts of laser to finely reshape the cornea, effectively correcting astigmatism along with other common vision problems like nearsightedness and farsightedness. The process involves the removal of corneal tissue with an accuracy that allows more than 90% of patients to achieve normal distant vision.