The astigmatism is a refractive error where the refractive power is not the same on all the meridians (the cornea has a radius of curvature on one axis and it has a different radius of curvature on the perpendicular meridian).

In the case of regular astigmatism, the main meridians are perpendicular. In the ophthalmologic practice, the irregular astigmatism may also be encountered (e.g. keratoconus), for which the therapeutic approach is more complex.

The patients with astigmatism do not see clarly at any distance (nor faraway nor near distance)

The astigmatism is corrected with cylindrical or sphero-cylindrical lenses.

Children generally accept total correction of astigmatism (after cycloplegia), but many adults prefer a under-correction of the astigmatism.

For a patient aged of up to 20 years old, the treatment consists of air correction (glasses) or toric contact lenses.

For patients aged from 20 to 40, the treatment may consist of refractive surgery (iLASIK).

After 40 or 45 years of age, the treatment is customised, upon a case-by-case basis, depending on the level of astigmatism and the lens condition.