Someone who is astigmatic has imprecise near and far vision. In particular, in peripheral vision images can sometimes appear deformed. Astigmatism may be combined with other eyesight problems such as hyperopia, myopia.
Astigmatism causes: a parallax error
Astigmatism is mainly caused by an irregular curvature of the cornea. As a result, the image is not formed properly on the retina, but distorted according to the curvature of the cornea.
Symptoms: confuse letters and numbers while reading
An astigmatic person has difficulty clearly distinguishing certain shapes and details, and seeing the contrasts between horizontal, vertical or oblique lines. This can result in confusion between letters and numbers such as O, D, Q, G, 6, 9 and 8. If a child has learning difficulties in literacy and numeracy, drawing or even writing on lines, it may be astigmatism. Given the consequences of astigmatism on a child’s evolution, it’s important to carry out a vision test regularly.
Astigmatism solutions: toric lenses
To compensate this defect of the cornea, toric lenses are used which are curved and of varying thickness to redirect light rays to the retina. This lens is designed to compensate for the corneal curvature and correct its astigmatism. The stronger the astigmatism, the greater the difference in thickness of the lens.