Abstract
The dome shape of the cornea is spherical as long as all the meridians have the same curvature. In astigmatism the refractive power of the cornea varies in its vertical and horizontal meridians, and therefore a point image of a point object cannot be formed. The meridians of maximum and minimum curvature are called the principal meridians, and in regular astigmatism these are at 90° to each other. From the curvature of the cornea, the mean corneal power and the cylinder power can be calculated, and clinically this is described by the axis of the cylinder and its power in dioptres (D) [1].
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Blum, M., Sekundo, W. (2015). Astigmatism Correction. In: Sekundo, W. (eds) Small Incision Lenticule Extraction (SMILE). Springer, Cham. https://doi.org/10.1007/978-3-319-18530-9_8
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DOI: https://doi.org/10.1007/978-3-319-18530-9_8
Publisher Name: Springer, Cham
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