How can you calculate the corneal astigmatism?

Corneal astigmatism can be calculated using keratometry, which measures the curvature of the cornea in different meridians. By determining the steepest and flattest corneal radii, the difference between these measurements (in diopters) can indicate the degree of astigmatism. Additionally, corneal topography can provide a detailed map of the corneal surface, allowing for a more comprehensive analysis of astigmatism. These methods help in diagnosing and guiding corrective measures, such as glasses or contact lenses.